GroupDIY

Project Specific Discussions => Mixers/Monitoring Systems => Topic started by: Jannee on June 27, 2014, 08:45:53 AM

Title: 24ch API SUMMING MIXER DR-2402
Post by: Jannee on June 27, 2014, 08:45:53 AM
Hi!

Anyone else building this?

http://www.diy-racked.com/diy-talk/viewtopic.php?f=7&t=234

Janne
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: DIY-solder on June 27, 2014, 10:14:26 AM
I know at least 7 of them  ;)

Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Trench Recordings on June 27, 2014, 02:26:13 PM
who made the DR-2402 board ? looking for more info
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Jannee on June 28, 2014, 07:03:25 AM
who made the DR-2402 board ? looking for more info

Pretty much all info so far is in the link above.

Janne
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ipagel on July 27, 2014, 08:00:05 AM
Did anymore information turn up on this? Or has anyone finished the project. I am very interested.

Ignore above message found more info on Facebook.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Jannee on July 27, 2014, 08:01:52 PM
Well, I should be getting the boards and the case in two weeks. I'll give you all info when I get to it. There is a bom on diy-racked facebook page.

Janne


quote author=ipagel link=topic=56568.msg724557#msg724557 date=1406462405]
Did anymore information turn up on this? Or has anyone finished the project. I am very interested.

Ignore above message found more info on Facebook.
[/quote]
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: beatnik on July 28, 2014, 04:29:40 AM
keep us posted! that is a cool project indeed
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ipagel on July 28, 2014, 07:52:03 AM
I got in touch and hopefully will be able to get one.

Let use know how ou get on.

M
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: no_doz on July 29, 2014, 07:42:45 PM
This looks like exactly what I want...direct outs!
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: PD on September 15, 2014, 06:03:07 PM
I got my case and boards. In the process of sourcing parts.  Will post more info as I get further along. Really nice looking case and boards.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Bobby Baird on September 15, 2014, 07:27:24 PM
How many doa in this thing? Is it a 5u 19" rack mount? How much rough estimate to build one ?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: kante1603 on September 16, 2014, 01:12:55 AM
Is that an API logo on the frontpanel?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: PD on September 16, 2014, 10:03:19 AM
28 doa's (24 channels  and 4 on the summing section),  3 rack space.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Electrobumps on September 22, 2014, 07:31:49 PM
This is interesting, I've been thinking about putting together an API style summing mixer and looking at some of the classic API options. 

The 2520 in this project  is very API as is the logo on the front panel!

What are peoples thoughts on the TL704's and THAT 1646's and no output transformers?   

Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Spiritworks on October 26, 2014, 12:20:33 PM
I would be interested to hear more about this project. Is it actually available yet?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: djfatum on October 24, 2015, 05:32:50 AM
:-)
amazing design
great sound



(https://scontent-fra3-1.xx.fbcdn.net/hphotos-xta1/v/t1.0-9/11659364_681560581974855_8206978320481954084_n.jpg?oh=ecde708350cc20363c8623a8a262d05c&oe=56894BE4)

(https://scontent-fra3-1.xx.fbcdn.net/hphotos-xpt1/v/t1.0-9/11988293_681243562006557_5873098753886493776_n.jpg?oh=aae8b3ce2deca1fb70e8dbe058f47d13&oe=56D289B7)

(https://scontent-fra3-1.xx.fbcdn.net/hphotos-xpf1/v/t1.0-9/11986970_680827382048175_8822191127005692224_n.jpg?oh=25e9fc38def0e8a1adbdb07edb50a5b6&oe=56CFA870)

(https://fbcdn-sphotos-b-a.akamaihd.net/hphotos-ak-xpl1/v/t1.0-9/11953286_680827375381509_2850401981453007037_n.jpg?oh=845f06c8b20e4d1506039b9e7c65786d&oe=56BC77AC&__gda__=1454773792_e9cd74ce997c6cf022312f076f262e75)

(https://scontent-fra3-1.xx.fbcdn.net/hphotos-xfa1/v/t1.0-9/10897035_680827088714871_2522919513635600583_n.jpg?oh=97f54fe09a9506d2b9fa91837ddb6433&oe=56BAECCE)

(https://scontent-fra3-1.xx.fbcdn.net/hphotos-xpl1/v/t1.0-9/11988588_680826992048214_5232439915340064791_n.jpg?oh=dc55ff2888dd3e7ecc757191536264a1&oe=568C7C99)

(https://scontent-fra3-1.xx.fbcdn.net/hphotos-xpa1/v/t1.0-9/11053103_683445318453048_8452913422484946259_n.jpg?oh=532bd40a1b4a790575c758fb0818288d&oe=568A0D99)

(https://scontent-fra3-1.xx.fbcdn.net/hphotos-xfa1/v/t1.0-9/11990518_683445261786387_7753768702422035044_n.jpg?oh=fe75e4f5117efab06449eaf5ed9819f9&oe=56C5606D)

Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Bradovic on October 27, 2015, 07:14:43 AM
Incredible  :o
Is this kit still for sale?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: qmp audio on October 29, 2015, 04:22:06 PM
I am building one of these... slowly but surely in between other jobs.    About 20% there.
Anyone else?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: djfatum on October 29, 2015, 06:37:36 PM
I am building one of these... slowly but surely in between other jobs.    About 20% there.
Anyone else?

I already built  :-)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ZekeProductions on November 14, 2015, 09:30:58 PM
Incredible  :o
Is this kit still for sale?


I think Tat may have a few left but the project is closing, so be quick.


Cheers
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Humner on November 15, 2015, 02:21:32 AM
Looks really good. I can image it sounds great too  ;D

What is the purpose of the IC's on the input channel boards? I assume they are for peak + signal LEDs as mentioned in the features list.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on November 30, 2015, 04:45:59 PM
Just ordered the partial kit! Looking forward to the build. It`s going to take a while before I can order all the parts...
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on December 01, 2015, 04:57:20 AM
So, there are a few unclear things in the BOM. Some of the caps that are linked to in the bom are way under the voltage requirement stated in the BOM, like the 470uf one. What are people using for the bi-polar 22uf electros? Never encountered bipolar electros before.

I am also curious as to what people are using for the dual pots (ch 16-24) and what rotary switch for the master volume (the bom states a 21 turn one, which seems to be an odd value? going by the audiomaintenance switches here...)

And for the pan knob, would this work? http://capi-gear.com/catalog/product_info.php?cPath=50_131&products_id=446
The bom states a single gang pot (and not the usual dual for pan). The center detent is what`s important for me here.

Any input would be appreciated  8)

Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Le Roux on January 10, 2016, 02:08:12 PM
I'm in for one too! Stoked!!!  ;D
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: qmp audio on January 11, 2016, 12:31:02 PM
I am also curious as to what people are using for the dual pots (ch 16-24) and what rotary switch for the master volume (the bom states a 21 turn one, which seems to be an odd value? going by the audiomaintenance switches here...)

And for the pan knob, would this work? http://capi-gear.com/catalog/product_info.php?cPath=50_131&products_id=446
The bom states a single gang pot (and not the usual dual for pan). The center detent is what`s important for me here.

What did you end up using for pots?  I still need to get the dual 1k.

Pan pots,  single pole is fine for unbalanced:  http://capi-gear.com/catalog/product_info.php?cPath=50_131&products_id=308

Master,  i chose the CAPI elma:  http://capi-gear.com/catalog/product_info.php?cPath=51_133&products_id=400




Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: r2d2 on January 13, 2016, 09:44:55 AM
....same , but different diy layout of original Api Summ "set" ,
as in image?

r
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on January 14, 2016, 05:58:14 AM
I am also curious as to what people are using for the dual pots (ch 16-24) and what rotary switch for the master volume (the bom states a 21 turn one, which seems to be an odd value? going by the audiomaintenance switches here...)

And for the pan knob, would this work? http://capi-gear.com/catalog/product_info.php?cPath=50_131&products_id=446
The bom states a single gang pot (and not the usual dual for pan). The center detent is what`s important for me here.

What did you end up using for pots?  I still need to get the dual 1k.

Pan pots,  single pole is fine for unbalanced:  http://capi-gear.com/catalog/product_info.php?cPath=50_131&products_id=308

Master,  i chose the CAPI elma:  http://capi-gear.com/catalog/product_info.php?cPath=51_133&products_id=400

Hey, thanks for the feedback. I`m also looking for the dual 1k`s, I thought audiomaintenance had them, but doesn`t seem so.

I also see that CAPI has 470uf caps, but they seem to be 10V rated? Should go for 35V+ I presume from the BOM.
Also, when looking at bipolar electrolytics, these seem from the specs read at mouser etc, to have way shorter lifetime rating ? Like 2000 hours. Is this something to worry about?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: axl on January 14, 2016, 07:08:43 AM
Triyng to find all the part for starting this great project!
Anyone have a clue of where buy api knobs style??

Anyone have build these with pierpaolo's DOA?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on January 14, 2016, 05:15:38 PM
There are these for the dual 1k log:

http://www.jlmaudio.com/shop/dual-1k-log-pot.html

Don`t know how they would stand up to the bourns tough... probably not as accurate, and maybe feel is worse? I don`t know.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Ninuz on January 18, 2016, 10:13:50 AM
I went with the JLM ones. They are fine but one of the pots are actually a bit out of balance.
Im thinking about changing to Bourns or Spectrol ones as they are supposed to be very accurate and they Spectrol ones are smaller so will fit easier between the backplate.

There are these for the dual 1k log:

http://www.jlmaudio.com/shop/dual-1k-log-pot.html

Don`t know how they would stand up to the bourns tough... probably not as accurate, and maybe feel is worse? I don`t know.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on January 18, 2016, 02:55:11 PM
I`d love some links to where the bourns/spectrols are available  8)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Ninuz on January 19, 2016, 05:54:00 PM
Will let you know If I find any:)

I`d love some links to where the bourns/spectrols are available  8)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ZekeProductions on January 26, 2016, 10:40:15 PM
I'm not sure how good these are but here are the Dual 1k pots I have found:

http://www.mouser.com/ProductDetail/Alpha-Taiwan/RV24BF-10-15R1-A1K/?qs=sGAEpiMZZMtC25l1F4XBU70HIOTw2yVioKwu10nGPQY%3d

Anyone use them, any advice?


EDIT: you only need 4 of these not 8 like the BOM says.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on January 27, 2016, 01:36:00 PM
I`ve found these aswell:

http://www.reichelt.de/PO6S-LOG-1-0K/3/index.html?&ACTION=3&LA=446&ARTICLE=88253&artnr=PO6S-LOG+1%2C0K&SEARCH=PO6S-LOG+1%2C0K

Ninuz found and purchased these:

http://se.rs-online.com/web/p/potentiometers/5042728/?searchTerm=5042728&relevancy-data=636F3D3126696E3D4931384E525353746F636B4E756D6265724D504E266C753D656E266D6D3D6D61746368616C6C26706D3D5E5C647B367D247C5E5C647B377D247C5E5C647B31307D2426706F3D313426736E3D592673743D52535F53544F434B5F4E554D4245522677633D4E4F4E45267573743D3530343237323826

I`m guessing those are the only conductive plastic types so far? Probably the tightest tolerance?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ZekeProductions on February 02, 2016, 12:36:04 PM
I`ve found these aswell:

http://www.reichelt.de/PO6S-LOG-1-0K/3/index.html?&ACTION=3&LA=446&ARTICLE=88253&artnr=PO6S-LOG+1%2C0K&SEARCH=PO6S-LOG+1%2C0K

Ninuz found and purchased these:

http://se.rs-online.com/web/p/potentiometers/5042728/?searchTerm=5042728&relevancy-data=636F3D3126696E3D4931384E525353746F636B4E756D6265724D504E266C753D656E266D6D3D6D61746368616C6C26706D3D5E5C647B367D247C5E5C647B377D247C5E5C647B31307D2426706F3D313426736E3D592673743D52535F53544F434B5F4E554D4245522677633D4E4F4E45267573743D3530343237323826

I`m guessing those are the only conductive plastic types so far? Probably the tightest tolerance?

I looked into these and I wanted to know what would be the difference/benefits between the dual 1k alpha-twain that I found in mouser and the Vishay pots fragletrollet mentioned that Ninuz found. From my very poor knowledge the differences that I can see are conductive plastic vs carbon, Linear vs Audio Taper and price difference  ($25.37 for the Vishay and $3.19 for the Alpha [tawain]).  I guess my question would be which one is better for this project?


Thanks


Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Ninuz on February 03, 2016, 06:39:08 PM
Hi,
The Vishay from mouser is a Linear pot. For he volume pots in the mixer you will need Log Audio Pots and it was hard for me to find a dual ganged conductive plastic pot which I did att RS online.
Another reason I choose the Vishay pot is because its quite small and the space on the back plate on the front panel is quite narrow. Of course you could cut of some of the metal if you need more space. I think the Alpha you found is a bit big in size and you shouldnt go bigger than a 16mm if you want to fit it without modding the backplate.

For the pan pots you will need Linear pots.
I found these for the Pan which Im thinking about getting as they are center detended. The are dual ganged but I suppose you could just use 1 gang and ignore the other one.
http://capi-gear.com/catalog/product_info.php?cPath=50_131&products_id=446
At the moment in my mixer I have Alpha 16mm which works fine.
The 16mm Alpha are quite cheap and has a really well known feel.

I`ve found these aswell:

http://www.reichelt.de/PO6S-LOG-1-0K/3/index.html?&ACTION=3&LA=446&ARTICLE=88253&artnr=PO6S-LOG+1%2C0K&SEARCH=PO6S-LOG+1%2C0K

Ninuz found and purchased these:

http://se.rs-online.com/web/p/potentiometers/5042728/?searchTerm=5042728&relevancy-data=636F3D3126696E3D4931384E525353746F636B4E756D6265724D504E266C753D656E266D6D3D6D61746368616C6C26706D3D5E5C647B367D247C5E5C647B377D247C5E5C647B31307D2426706F3D313426736E3D592673743D52535F53544F434B5F4E554D4245522677633D4E4F4E45267573743D3530343237323826

I`m guessing those are the only conductive plastic types so far? Probably the tightest tolerance?

I looked into these and I wanted to know what would be the difference/benefits between the dual 1k alpha-twain that I found in mouser and the Vishay pots fragletrollet mentioned that Ninuz found. From my very poor knowledge the differences that I can see are conductive plastic vs carbon, Linear vs Audio Taper and price difference  ($25.37 for the Vishay and $3.19 for the Alpha [tawain]).  I guess my question would be which one is better for this project?


Thanks
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Ninuz on February 03, 2016, 06:39:53 PM
Here is my finished mixer.

Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Ninuz on February 03, 2016, 06:45:04 PM
And a picture from inside. Need to clean up the cabling a bit;)
Most DOA's are from APP ( Pier Paolo) which I can really recommend.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on February 04, 2016, 05:43:40 AM
Ninuz, that`s beautiful! :)

I have a few more questions regarding parts:
1uf electrolytics: BOM calls for "low essr". How low are we speaking here? A link to a suitable cap from Mouser`s  inventory would be appreciated.
The same applies to the "Audio" 470uF electro, again a link to a Mouser cap would be appreciated.

Is this a good choice for the bipolar electro? I see the lifetime rating of bipolars are way lower than ordinary polarized electro`s. Something to think about?
http://no.mouser.com/Search/ProductDetail.aspx?R=UEP1E220MEDvirtualkey64700000virtualkey647-UEP1E220MED

This one good for the 1000uf?
http://no.mouser.com/Search/ProductDetail.aspx?R=EEU-FR1V102virtualkey66720000virtualkey667-EEU-FR1V102


And a question regarding the chassis: the back-panel has 8 xlr-cutouts in addition to the power inlet. So,  send/return (4), main out (2) and... a second set of outputs from the aca/bo?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on February 04, 2016, 06:19:16 AM
Hi,
The Vishay from mouser is a Linear pot. For he volume pots in the mixer you will need Log Audio Pots and it was hard for me to find a dual ganged conductive plastic pot which I did att RS online.
Another reason I choose the Vishay pot is because its quite small and the space on the back plate on the front panel is quite narrow. Of course you could cut of some of the metal if you need more space. I think the Alpha you found is a bit big in size and you shouldnt go bigger than a 16mm if you want to fit it without modding the backplate.

For the pan pots you will need Linear pots.
I found these for the Pan which Im thinking about getting as they are center detended. The are dual ganged but I suppose you could just use 1 gang and ignore the other one.
http://capi-gear.com/catalog/product_info.php?cPath=50_131&products_id=446
At the moment in my mixer I have Alpha 16mm which works fine.
The 16mm Alpha are quite cheap and has a really well known feel.

I`ve found these aswell:

http://www.reichelt.de/PO6S-LOG-1-0K/3/index.html?&ACTION=3&LA=446&ARTICLE=88253&artnr=PO6S-LOG+1%2C0K&SEARCH=PO6S-LOG+1%2C0K

Ninuz found and purchased these:

http://se.rs-online.com/web/p/potentiometers/5042728/?searchTerm=5042728&relevancy-data=636F3D3126696E3D4931384E525353746F636B4E756D6265724D504E266C753D656E266D6D3D6D61746368616C6C26706D3D5E5C647B367D247C5E5C647B377D247C5E5C647B31307D2426706F3D313426736E3D592673743D52535F53544F434B5F4E554D4245522677633D4E4F4E45267573743D3530343237323826

I`m guessing those are the only conductive plastic types so far? Probably the tightest tolerance?

I looked into these and I wanted to know what would be the difference/benefits between the dual 1k alpha-twain that I found in mouser and the Vishay pots fragletrollet mentioned that Ninuz found. From my very poor knowledge the differences that I can see are conductive plastic vs carbon, Linear vs Audio Taper and price difference  ($25.37 for the Vishay and $3.19 for the Alpha [tawain]).  I guess my question would be which one is better for this project?


Thanks

By the way, I think I will go for these for the pan-pots. Will go nicely with the level pots...

http://capi-gear.com/catalog/product_info.php?cPath=50_131&products_id=308

Where did you get your API knobs Ninuz?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ZekeProductions on February 04, 2016, 02:58:40 PM
Ninuz, that`s beautiful! :)

I have a few more questions regarding parts:
1uf electrolytics: BOM calls for "low essr". How low are we speaking here? A link to a suitable cap from Mouser`s  inventory would be appreciated.
The same applies to the "Audio" 470uF electro, again a link to a Mouser cap would be appreciated.

Is this a good choice for the bipolar electro? I see the lifetime rating of bipolars are way lower than ordinary polarized electro`s. Something to think about?
http://no.mouser.com/Search/ProductDetail.aspx?R=UEP1E220MEDvirtualkey64700000virtualkey647-UEP1E220MED

This one good for the 1000uf?
http://no.mouser.com/Search/ProductDetail.aspx?R=EEU-FR1V102virtualkey66720000virtualkey667-EEU-FR1V102


And a question regarding the chassis: the back-panel has 8 xlr-cutouts in addition to the power inlet. So,  send/return (4), main out (2) and... a second set of outputs from the aca/bo?

for the 470uf this was recommended to me:

http://www.mouser.com/Search/ProductDetail.aspx?R=EEU-FC1V471virtualkey66720000virtualkey667-EEU-FC1V471

I plan on getting the same 1000uf but maybe Ninuz has a better recommendation

Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ZekeProductions on February 04, 2016, 03:07:15 PM
Hi,
The Vishay from mouser is a Linear pot. For he volume pots in the mixer you will need Log Audio Pots and it was hard for me to find a dual ganged conductive plastic pot which I did att RS online.
Another reason I choose the Vishay pot is because its quite small and the space on the back plate on the front panel is quite narrow. Of course you could cut of some of the metal if you need more space. I think the Alpha you found is a bit big in size and you shouldnt go bigger than a 16mm if you want to fit it without modding the backplate.

For the pan pots you will need Linear pots.
I found these for the Pan which Im thinking about getting as they are center detended. The are dual ganged but I suppose you could just use 1 gang and ignore the other one.
http://capi-gear.com/catalog/product_info.php?cPath=50_131&products_id=446
At the moment in my mixer I have Alpha 16mm which works fine.
The 16mm Alpha are quite cheap and has a really well known feel.

I`ve found these aswell:

http://www.reichelt.de/PO6S-LOG-1-0K/3/index.html?&ACTION=3&LA=446&ARTICLE=88253&artnr=PO6S-LOG+1%2C0K&SEARCH=PO6S-LOG+1%2C0K

Ninuz found and purchased these:

http://se.rs-online.com/web/p/potentiometers/5042728/?searchTerm=5042728&relevancy-data=636F3D3126696E3D4931384E525353746F636B4E756D6265724D504E266C753D656E266D6D3D6D61746368616C6C26706D3D5E5C647B367D247C5E5C647B377D247C5E5C647B31307D2426706F3D313426736E3D592673743D52535F53544F434B5F4E554D4245522677633D4E4F4E45267573743D3530343237323826

I`m guessing those are the only conductive plastic types so far? Probably the tightest tolerance?

I looked into these and I wanted to know what would be the difference/benefits between the dual 1k alpha-twain that I found in mouser and the Vishay pots fragletrollet mentioned that Ninuz found. From my very poor knowledge the differences that I can see are conductive plastic vs carbon, Linear vs Audio Taper and price difference  ($25.37 for the Vishay and $3.19 for the Alpha [tawain]).  I guess my question would be which one is better for this project?


Thanks

By the way, I think I will go for these for the pan-pots. Will go nicely with the level pots...

http://capi-gear.com/catalog/product_info.php?cPath=50_131&products_id=308

Where did you get your API knobs Ninuz?

Thanks for the clarification Ninuz, I understand now. The ones at RS are Audio log and the mouser is Linear log. That is what I was confused about. Funny how they have the same model number though.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Ninuz on February 05, 2016, 06:01:34 PM
Should be fine. Just check diameter and spacing pitch so they fit the PCB.
Did you get the external box for the PSU board? If not I would recommend it as it gets to hot inside the rack case which can cause some problems. Also use shielded cable for as much cabling as possible. 

Ninuz, that`s beautiful! :)

I have a few more questions regarding parts:
1uf electrolytics: BOM calls for "low essr". How low are we speaking here? A link to a suitable cap from Mouser`s  inventory would be appreciated.
The same applies to the "Audio" 470uF electro, again a link to a Mouser cap would be appreciated.

Is this a good choice for the bipolar electro? I see the lifetime rating of bipolars are way lower than ordinary polarized electro`s. Something to think about?
http://no.mouser.com/Search/ProductDetail.aspx?R=UEP1E220MEDvirtualkey64700000virtualkey647-UEP1E220MED

This one good for the 1000uf?
http://no.mouser.com/Search/ProductDetail.aspx?R=EEU-FR1V102virtualkey66720000virtualkey667-EEU-FR1V102


And a question regarding the chassis: the back-panel has 8 xlr-cutouts in addition to the power inlet. So,  send/return (4), main out (2) and... a second set of outputs from the aca/bo?

for the 470uf this was recommended to me:

http://www.mouser.com/Search/ProductDetail.aspx?R=EEU-FC1V471virtualkey66720000virtualkey667-EEU-FC1V471

I plan on getting the same 1000uf but maybe Ninuz has a better recommendation
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Ninuz on February 05, 2016, 06:03:48 PM
I used mostly Pier APP992. Works and sounds nice:)


Triyng to find all the part for starting this great project!
Anyone have a clue of where buy api knobs style??

Anyone have build these with pierpaolo's DOA?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on February 12, 2016, 09:33:20 PM
Is the direct outs pre or post faders?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ZekeProductions on February 23, 2016, 03:15:28 PM
I`ve found these aswell:

http://www.reichelt.de/PO6S-LOG-1-0K/3/index.html?&ACTION=3&LA=446&ARTICLE=88253&artnr=PO6S-LOG+1%2C0K&SEARCH=PO6S-LOG+1%2C0K

Ninuz found and purchased these:

http://se.rs-online.com/web/p/potentiometers/5042728/?searchTerm=5042728&relevancy-data=636F3D3126696E3D4931384E525353746F636B4E756D6265724D504E266C753D656E266D6D3D6D61746368616C6C26706D3D5E5C647B367D247C5E5C647B377D247C5E5C647B31307D2426706F3D313426736E3D592673743D52535F53544F434B5F4E554D4245522677633D4E4F4E45267573743D3530343237323826

I`m guessing those are the only conductive plastic types so far? Probably the tightest tolerance?

I looked into these and I wanted to know what would be the difference/benefits between the dual 1k alpha-twain that I found in mouser and the Vishay pots fragletrollet mentioned that Ninuz found. From my very poor knowledge the differences that I can see are conductive plastic vs carbon, Linear vs Audio Taper and price difference  ($25.37 for the Vishay and $3.19 for the Alpha [tawain]).  I guess my question would be which one is better for this project?


Thanks

I spoke with mouser today and they clarified that their was an error on the page. The part that I posted in the comparison is actually an Audio Taper, the mouser webpage was wrong. They will report the webpage for correction.

Here is the part at mouser.

http://www.mouser.com/ProductDetail/Vishay/P9A2R100FISX1102ML/?qs=%2fha2pyFaduj5EYn41UZWkFYdBorExN%2f%252bVqEvRsJSRBoziifoUjcBuA%3d%3d
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on February 24, 2016, 05:42:07 AM
Those are some expensive pots!
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ZekeProductions on February 24, 2016, 09:13:02 AM
These and the alpha's I found are the only dual 1k pots I can find here in the USA.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ZekeProductions on March 08, 2016, 11:00:29 AM
I see some people have used terminal blocks for the channel board (BUS & +/-16v) and the 2-ACA-BO boards (see attached pic). Does anyone know the pitch length for these? I am pretty sure it is 3.96mm but I can't seem to find any on mous*r.com or Farn*ll

will these fit?
http://www.mouser.com/Search/ProductDetail.aspx?R=284392-3virtualkey57110000virtualkey571-284392-3

Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: porkyman on March 11, 2016, 01:14:57 AM
anyone have an estimate on total cost?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: JessJackson on March 11, 2016, 04:27:48 AM
anyone have an estimate on total cost?

about 1k to 1.2k
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on March 11, 2016, 03:29:56 PM
What.... Id say that its more in the 1500-2000 range (€)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Le Roux on March 11, 2016, 06:56:27 PM
My mouser cart is up to $1100US and that doesnt include board/case costs, ACA board and transformers, or the 2520's.

All said and done, I'm thinking I will be over $3k Canadian.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: JessJackson on March 11, 2016, 10:47:27 PM
My mouser cart is up to $1100US and that doesnt include board/case costs, ACA board and transformers, or the 2520's.

All said and done, I'm thinking I will be over $3k Canadian.

my mouser cart is way less..

you have to check to see if its cheaper to buy 100 than 24 of certain items because it can be the difference between 0.20c and 0.02cents
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Le Roux on March 12, 2016, 07:37:17 AM

my mouser cart is way less..

you have to check to see if its cheaper to buy 100 than 24 of certain items because it can be the difference between 0.20c and 0.02cents
[/quote]

Thanks for the tip! :) I will be sure to check that!!
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on March 12, 2016, 07:54:44 AM
So can anyone tell me about the feel of the Bourns pots from the BOM (for the mono channels level) :

http://no.mouser.com/Search/ProductDetail.aspx?R=91A1A-B24-D10Lvirtualkey65210000virtualkey652-91A1A-B24-D10L

I`ve used conductive plastic pots in the Bluzzi`s 1084 builds:

https://www.digikey.no/product-detail/en/bourns-inc/91A1A-B24-B15L/91A1A-B24-B15L-ND/1089381

and am not happy about the "feel". Way too light to turn. I`d like something along the feel of the CAPI T-PAD.
I talked to Jeff from Capi, and he advised me these:

http://capi-gear.com/catalog/product_info.php?cPath=50_131&products_id=227

However he will not restock them, and I have to save more money before I can purchase the next round of parts. Jeff also mentioned the BI-pots, that are much cheaper and have a similar feel. However he does not stock the 1k value.

...so, any tips?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Rob Flinn on March 12, 2016, 03:44:39 PM
use the Bournes pots because they are really good quality.    Split a rubber grommet in half & put it on the shaft behind the knob so it creates a bit of friction between the knob & the panel.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: buckethead on March 13, 2016, 10:31:53 AM
Hi guys!

I'm building one of those too and have almost all the parts ready by now. Total cost I'd say 2000-2500€

How did you guys mount the LEDs? Still thinking of a good way to solve that problem...

Best regards,
Mathias
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Ninuz on March 13, 2016, 03:15:05 PM
I used epoxy glue.
Same for the framing of the Sifam meters I used as the mounting set/bolt and nuts didnt fit.
 

Hi guys!

I'm building one of those too and have almost all the parts ready by now. Total cost I'd say 2000-2500€

How did you guys mount the LEDs? Still thinking of a good way to solve that problem...

Best regards,
Mathias
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: buckethead on March 13, 2016, 11:23:59 PM
I used epoxy glue.
Same for the framing of the Sifam meters I used as the mounting set/bolt and nuts didnt fit.

So you glued the LEDs and the meters directly to the frontpanel? I was thinking about that too...but I'm not giving up trying to find a "nicer" way to mount those ;)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: qmp audio on March 14, 2016, 02:58:13 PM
Jeff also mentioned the BI-pots, that are much cheaper and have a similar feel. However he does not stock the 1k value.

...so, any tips?

I'm planning on making my own front panel,  and using concentric level/pan:
http://capi-gear.com/catalog/product_info.php?cPath=50_131&products_id=445

I don't see a reason why that wouldn't work.

I already got 16 of the pan pots from CAPI,  so I may sell those if anyone needs them (http://capi-gear.com/catalog/product_info.php?cPath=50_131&products_id=308)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Ninuz on March 17, 2016, 10:03:30 AM
It was the only solution I found at the time being.
The Sifam meters did include a mounting set which let the meter frame be mounted with screws and bolts but as the meters are placed near each other its not possible on the panel included in the kit.

I used epoxy glue.
Same for the framing of the Sifam meters I used as the mounting set/bolt and nuts didnt fit.

So you glued the LEDs and the meters directly to the frontpanel? I was thinking about that too...but I'm not giving up trying to find a "nicer" way to mount those ;)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on March 26, 2016, 06:01:57 AM
A question regarding the toroid supplied for the PSU:  are the primaries the white and black cables, and secondaries the red/blue? How do you identify the x1-x4?

(http://s10.postimg.org/6qzau4nc9/toroid.jpg)


Also a question about the VU meters: I`m using the one from Hairball, that came with a plastic frame and a set of screws/plastic fasteners to fasten it to the front panel. However, it seems that the needle-adjustment screw on the bottom front of the meter prevents the meter to stand flush with the panel?

(http://s30.postimg.org/kt3n0jd0x/20160326_115551.jpg)

(http://s13.postimg.org/481ptd46f/20160326_115547.jpg)

(http://s7.postimg.org/krhj3762j/not_flush.jpg)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: buckethead on March 26, 2016, 01:21:12 PM
Hi!

I routed two small pockets to make them fit (sorry, the image quality is really bad, but you'll get the point):

(http://www.mordpol.com/img1.jpg)

The black and white cables are the primaries.  You can use the secondaries like this:

(http://www.mordpol.com/toroid.jpg)

Have a nice one!

Mathias

Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: buckethead on March 26, 2016, 02:25:49 PM
P.S.:

I made small brass holders to mount the meters, didn't want to glue them to the front with epoxy:

(http://www.mordpol.com/img2.jpg)

(http://www.mordpol.com/img3.jpg)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on March 26, 2016, 02:33:14 PM
With your custom brass hardware, did you end up mounting the meters a little "into" the unit? Or did you manage to route enough out of the front panel to fit the screw?

I think routing will be the way I`ll go then. Hope I dont screw it up (no pun intended  ;D)

And thanks for the picture of the toroid  8)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: buckethead on March 26, 2016, 03:47:47 PM
I made the pocket deep enough for the whole screw to fit in, so the meters are lying flat on the front panel (or rather on the black mounting frames). But it was a real pain to take away that much material, I was shopping for a new front panel in my head while drilling :)

Looks like some of the other guys mounted them a little angled...

Good luck man!
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on March 26, 2016, 05:18:53 PM
Yes it does not look that "angled" when seen from the front (fitted as is). My local hackerspace has a very nice CNC, might be a mission for it  8) Did you use a hand-drill?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: buckethead on March 27, 2016, 09:05:32 PM
Yeah, I used a hand drill with a metal drill bit at first and then some router bit to deepen it. Quick and dirty!
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: JessJackson on March 29, 2016, 02:56:53 PM
u guys are fast, I'm still building op amps! smh
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on March 30, 2016, 01:58:34 AM
Yeah I finished 26 opamps a few days ago... I know it gets a little tedious after a while :) Altough I know the gar2520 by heart by now  8)

Now if I only had the money for the last order  :o
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on April 07, 2016, 09:08:57 AM
Should be fine. Just check diameter and spacing pitch so they fit the PCB.
Did you get the external box for the PSU board? If not I would recommend it as it gets to hot inside the rack case which can cause some problems. Also use shielded cable for as much cabling as possible. 

Ninuz, that`s beautiful! :)

I have a few more questions regarding parts:
1uf electrolytics: BOM calls for "low essr". How low are we speaking here? A link to a suitable cap from Mouser`s  inventory would be appreciated.
The same applies to the "Audio" 470uF electro, again a link to a Mouser cap would be appreciated.

Is this a good choice for the bipolar electro? I see the lifetime rating of bipolars are way lower than ordinary polarized electro`s. Something to think about?
http://no.mouser.com/Search/ProductDetail.aspx?R=UEP1E220MEDvirtualkey64700000virtualkey647-UEP1E220MED

This one good for the 1000uf?
http://no.mouser.com/Search/ProductDetail.aspx?R=EEU-FR1V102virtualkey66720000virtualkey667-EEU-FR1V102


And a question regarding the chassis: the back-panel has 8 xlr-cutouts in addition to the power inlet. So,  send/return (4), main out (2) and... a second set of outputs from the aca/bo?

for the 470uf this was recommended to me:

http://www.mouser.com/Search/ProductDetail.aspx?R=EEU-FC1V471virtualkey66720000virtualkey667-EEU-FC1V471

I plan on getting the same 1000uf but maybe Ninuz has a better recommendation


Argh. I am fretting over the cap choices for this one.

The BOM says the 22uF should be bipolar, but lists "audio" in the rightmost category.
Bipolars on Mouser seem to have pretty short "lifetime" rating, between 1000-2000 hours that seem really short to me. Also, selecting "bipolar" and "audio" are either/or categories, so getting one that is applicable in both categories is not possible.

Help a confused brother out  :o
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on April 07, 2016, 09:11:34 AM
Also, if someone could clarify abit about the "low essr" comment. What is considered "low essr"? What would be the consequence of using "high" essr caps in this circuit?

I must confess I`ve allready stuffed caps on the lower part of the pcb`s without thinking about "audio caps/low essr caps", as I figured that this is all concerning the LED driver (caps around the TL074) and that the choice of caps wouldn`t affect the unit too much. But when it comes to the audio-part of the pcb... I want to get it right.

I was also recommended to switch out the LM337 to an LM338, and the same for the LM317. I can however not find a suitable replacement for the 317. Any advice? Also wondering on what heatsinks you guys used, all the ones I seem to find are pretty small in size (again was recommended getting a big one) and I`d like one that fits the footprint of the pcb nicely.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Andy Peters on April 07, 2016, 03:07:48 PM
The BOM says the 22uF should be bipolar, but lists "audio" in the rightmost category.
Bipolar on Mouser seem to have pretty short "lifetime" rating, between 1000-2000 hours that seem really short to me.

The lifetime specs is for the capacitor operating at its maximum temperature rating, which is for the cheaper caps 85ºC, for less cheaper caps 105ºC, and for stuff that has to last forever, 125ºC.

The rule of thumb is that a capacitor's lifetime is doubled for every 10ºC decrease in temperature. The cap rated for 1000 hours at 85ºC should last for 32,000 hours at 35ºC.

The operating temperature also needs to include self-heating from ripple current due to cap ESR.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Andy Peters on April 07, 2016, 03:22:14 PM
Also, if someone could clarify abit about the "low essr" comment. What is considered "low essr"? What would be the consequence of using "high" ussr caps in this circuit?

I can't find a schematic for this thing, so I don't know how the caps are being used.

That said, "low ESR" is generally considered under an ohm. 

In an audio-path DC blocking circuit, ESR is probably not all that important.

When used for power-supply smoothing (after a rectifier or a switcher), ESR is important because the higher the ESR, the more self-heating in the capacitor, which reduces its lifetime. Also for switch-mode power supplies, the ESR is important because it affects the efficiency of the supply.

With some low-dropout linear regulators, RTFDS because they may specify a minimum ESR. With large-value ceramic capacitors being readily available (replacing tantalums in many applications), the ESR is so low that the LDO may oscillate.


Quote
I was also recommended to switch out the LM337 to an LM338

That would be potentially disastrous, as the LM337 is a negative regulator and the LM338 is a positive regulator.

Quote
and the same for the LM317. I can however not find a suitable replacement for the 317. Any advice?

The replacement for the 317 is the 338. But why? Do you need the current-source capacity of the 338? Does the design draw more than the 1.5 A the LM317 can do in the TO-220 package (with appropriate heat-sinking)?

-a
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on April 07, 2016, 04:48:48 PM
Hey Andy,

thank you so much for your in-depth answer regarding the caps/esr! Makes me able to take a more educated choice.

Ofcourse, I mis-spelled the regulators, and indeed, was intending to swap the 317 for the 338 (and needed something to swap the 337 with to match the 338`s 5a current limit).
I have not built up the mixer yet, so have not measured the actual current draw reqiurements. However, headroom is always nice, and I`m presuming it would produce less heat aswell? The advice came from the tech affiliated with the project, so I take his advice with some seriousness  8) (what can a noob do)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Andy Peters on April 07, 2016, 06:01:34 PM
I have not built up the mixer yet, so have not measured the actual current draw reqiurements. However, headroom is always nice, and I`m presuming it would produce less heat aswell?

Heat dissipation is a function of current draw and voltage drop, which will be the same for either regulator given the same input and output voltages.

You can reduce regulator heat dissipation by using a low-dropout regulator such as LT1963, which has a max dropout voltage of 450 mV at full tilt boogie, compared with about 2.25 V for the LM317. With 1.5 A load, that's 675 mW vs 3.75 W, which is significant.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on April 07, 2016, 06:25:32 PM
Thanks, but afaik (going from the ds)

Quote
The devices are available in fixed
output voltages of 1.5V, 1.8V, 2.5V, 3.3V

I`m having a hard time that would be sufficient, afaik the mixer runs on +16V? (jn addition to the negative rail)

Anyways, I`m probably overthinking this. I guess all the other peeps in this thread have built it up with the 317/337 combo and have no problems.

Anybody have a (mouser preferrably) link to  suitable heatsinks?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: buckethead on April 07, 2016, 06:33:54 PM
I use these heatsinks, they fit perfectly: http://www.mouser.at/Search/ProductDetail.aspx?R=513102B02500Gvirtualkey53210000virtualkey532-513102B25

I'm using 317/337s, will see if they can handle this thing. Hopefully I get this thing running very soon, then I'll measure the current draw and let you know
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: KasperNyhus on April 09, 2016, 09:53:27 PM
Does anybody have the schematics for this fine build?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: buckethead on April 10, 2016, 03:21:33 PM
Got it running for some first tests, the heatsinks from my previous post are way too small.  I don't know if there's a big enough heatsink to fit the footprint , maybe this one here: http://www.mouser.at/ProductDetail/Aavid-Thermalloy/531302B02500G/?qs=sGAEpiMZZMttgyDkZ5WiuntoNcpZWtUr7zxRApYWSuw%3d

The mixer draws about 0,8-1A current per rail, so ~8-10W of power to dissipate for the regulators...
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: djfatum on April 13, 2016, 05:46:26 AM
I used epoxy glue.
Same for the framing of the Sifam meters I used as the mounting set/bolt and nuts didnt fit.

So you glued the LEDs and the meters directly to the frontpanel? I was thinking about that too...but I'm not giving up trying to find a "nicer" way to mount those ;)




(https://scontent-fra3-1.xx.fbcdn.net/v/t1.0-9/11940719_680060788791501_5123754125207830957_n.jpg?oh=eaa7621f3ab34df2864b08b2b0ab1ab2&oe=57B75B55)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: djfatum on April 13, 2016, 05:50:46 AM
Got it running for some first tests, the heatsinks from my previous post are way too small.  I don't know if there's a big enough heatsink to fit the footprint , maybe this one here: http://www.mouser.at/ProductDetail/Aavid-Thermalloy/531302B02500G/?qs=sGAEpiMZZMttgyDkZ5WiuntoNcpZWtUr7zxRApYWSuw%3d

The mixer draws about 0,8-1A current per rail, so ~8-10W of power to dissipate for the regulators...

here is the high power consumption
Give large heatsink  there is a lot of heat
which leads to power off the controller

(https://scontent-fra3-1.xx.fbcdn.net/v/t1.0-9/10377253_681586438638936_2712111986537995076_n.jpg?oh=468a932df73494bf6c504ef7eea90107&oe=5776B242)

(https://scontent-fra3-1.xx.fbcdn.net/v/t1.0-9/12003033_683445315119715_323393520191242138_n.jpg?oh=daa1f22777847fdfa1b3699cd88ad08e&oe=57B29B2D)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Le Roux on April 13, 2016, 06:36:06 AM
Where did you get those knobs? :)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on April 13, 2016, 06:50:31 AM
Probably from Capi before they stopped selling them  ???

So, I got that I should get a big-ass heatsink, but seeing that fatum has the PSU in another enclosure than the PSU-enclosure coming from DIY-racked, I am wondering what heatsink fits the PSU-pcb. The one fatum uses is wider (atleast 2x) than what fits the pcb.

@Fatum:
The LED "bezels"/plastic "containter": have you glued these to the front-panel and/or the frontpanel-"help"-panel (the one directly behind the frontpanel) ?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on April 14, 2016, 01:53:56 AM
How much gain does each channel have?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: djfatum on April 15, 2016, 02:24:48 PM
Probably from Capi before they stopped selling them  ???

So, I got that I should get a big-ass heatsink, but seeing that fatum has the PSU in another enclosure than the PSU-enclosure coming from DIY-racked, I am wondering what heatsink fits the PSU-pcb. The one fatum uses is wider (atleast 2x) than what fits the pcb.

@Fatum:
The LED "bezels"/plastic "containter": have you glued these to the front-panel and/or the frontpanel-"help"-panel (the one directly behind the frontpanel) ?


I did not use glue :-)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: buckethead on April 24, 2016, 04:11:34 PM
Almost finished around here. The only things missing are a nice ELMA master volume switch and a bigger heatsink for the regulators. That thing was sooo much work, I'm glad it's almost over  ;D

For knobs I used OKW, they look nice and have a nice feel - and API knobs are impossible to get at the moment. I'll take some more pictures in the future, in case you guys are interested
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: buckethead on April 24, 2016, 04:12:25 PM
And another one
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: buckethead on April 24, 2016, 04:14:51 PM
last one for now
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Humner on April 24, 2016, 05:57:54 PM
Almost finished around here. The only things missing are a nice ELMA master volume switch and a bigger heatsink for the regulators. That thing was sooo much work, I'm glad it's almost over  ;D

For knobs I used OKW, they look nice and have a nice feel - and API knobs are impossible to get at the moment. I'll take some more pictures in the future, in case you guys are interested

wow! thats a cabling job to be proud of, well done. And good knob choice, white/black on blue is super clean I love it.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on April 25, 2016, 03:07:53 AM
Beautiful Buckethead!

What pots did you end up using? They kinda look like Alpha`s from the back... but that`s probably not the case?

Bet your pretty anxious to fire it up for the first time  8)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: buckethead on April 25, 2016, 05:52:27 AM
Thanks guys! ;)

The pots are from OMEG, they do custom work at a mininum order of 10 pcs. Not the cheapest solution, but they do really nice work and the pots fit that project perfectly! For the ones interested, you need to spend about 400€ (including 20% Austrian taxes) for those (25pcs PAN pots, 25pcs 1k faders, 10 pcs stereo 1k).

It's running fine with 16 channel at the moment, stereo channels are disconnected, because of the weak heatsinks.  But yeah, I have to admit there was some smoke development, when I turned it on the first time, hahaha.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Ninuz on April 26, 2016, 09:12:48 PM
I also had some some smoke when powering up:) Was a couple of op amps with a short.
I also had problems with the PSU shutting down one of the rails after about 20 minutes of use. I then added some cooling paste between the regulators and heatsink and also tightened them together with nuts and bolts and since then I dont get problems.

Thanks guys! ;)

The pots are from OMEG, they do custom work at a mininum order of 10 pcs. Not the cheapest solution, but they do really nice work and the pots fit that project perfectly! For the ones interested, you need to spend about 400€ (including 20% Austrian taxes) for those (25pcs PAN pots, 25pcs 1k faders, 10 pcs stereo 1k).

It's running fine with 16 channel at the moment, stereo channels are disconnected, because of the weak heatsinks.  But yeah, I have to admit there was some smoke development, when I turned it on the first time, hahaha.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ZekeProductions on April 26, 2016, 09:18:32 PM
Nice Work Buckethead! where did you get those knobs from? As everyone knows its almost impossible to get the apiish style knobs anymore.

Thanks for the Tip Ninuz. I'm still putting together the opamps (I've been taking it slow). Did you use the heatsink that fits on the PCB silkscreen or did you use a bigger one? I still have to order mine.

Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: buckethead on April 27, 2016, 06:29:56 AM
The knobs are from OKW (https://www.okw.com/). I'm still thinking about a good solution for the heatsinks. The PCB mounted small ones are just a little bit weak for that much power dissipation...
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Ninuz on April 27, 2016, 11:38:22 AM
Yeah those op amps takes time :(
I used the bom listed heatsinks and they are working but if you can find and use some bigger ones it wouldnt hurt I think.


Nice Work Buckethead! where did you get those knobs from? As everyone knows its almost impossible to get the apiish style knobs anymore.

Thanks for the Tip Ninuz. I'm still putting together the opamps (I've been taking it slow). Did you use the heatsink that fits on the PCB silkscreen or did you use a bigger one? I still have to order mine.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: warpie on April 27, 2016, 05:40:22 PM
What's the point of having the API logo on the panel?

EDIT: Ah, it's Purusha's case. That's why..  ::)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: buckethead on April 27, 2016, 08:43:32 PM
Oh yeah, you're right. Admittedly I was late on reading up on that whole Purusha topic and somehow new to the community and its "principles" when I started this project, I hope it's ok for the community to post about this project here.

The API logo is just ridiculous, removed it with acetone. Should have done that before taking pictures...
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: warpie on April 28, 2016, 05:28:29 AM
Very beautiful build by the way  :)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Le Roux on May 01, 2016, 09:58:40 AM
What value are you guys using for R1 & R5 on the ACA board?

Thanks
Neil
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on May 01, 2016, 01:02:29 PM
Going for the Elma 10k switch, so 51k  ;)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Le Roux on May 01, 2016, 01:42:46 PM
Haha, for some reason I thought that master volume was 25k that's why I was confused!  :-[

Thanks
Neil
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: lukas on May 03, 2016, 04:27:00 PM
Hey guys. I have few parts DR2402, and thinking this put together. Did i good thinking(pic's)?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on May 20, 2016, 03:03:58 PM
use the Bournes pots because they are really good quality.    Split a rubber grommet in half & put it on the shaft behind the knob so it creates a bit of friction between the knob & the panel.

Well so I tried this, and imo it didn`t work very well. Quite hard to get the same feel on all the pots.

Now that CAPI is almost empty of these:
http://capi-gear.com/catalog/product_info.php?cPath=50_131&products_id=227

anybody knows where I can get these from? Both Mouser and Digi-key has a 500 minimum order, as they are non-stocked. Or maybe I should go for the OMEG`s, as buckethead did.

I want that smoooth feeling when turning pots. The Bourns in the BOM are way too light to turn, and I want this mixer to shine  8)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: peskado on May 21, 2016, 09:19:01 AM
Try this
https://www.banzaimusic.com/CTS-270-1k-LOG.html
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ZekeProductions on May 22, 2016, 12:50:34 AM
use the Bournes pots because they are really good quality.    Split a rubber grommet in half & put it on the shaft behind the knob so it creates a bit of friction between the knob & the panel.

Well so I tried this, and imo it didn`t work very well. Quite hard to get the same feel on all the pots.

Now that CAPI is almost empty of these:
http://capi-gear.com/catalog/product_info.php?cPath=50_131&products_id=227

anybody knows where I can get these from? Both Mouser and Digi-key has a 500 minimum order, as they are non-stocked. Or maybe I should go for the OMEG`s, as buckethead did.

I want that smoooth feeling when turning pots. The Bourns in the BOM are way too light to turn, and I want this mixer to shine  8)

I would email Jeff at CAPI and ask him if he will be getting anymore soon. He only had 28 of the 10k center dent pots a few weeks ago and now he has 93 of them. You never know!

Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ZekeProductions on May 26, 2016, 10:24:37 PM
Ok, so I finally finished all my opamps (Phew) and I am at the point where I need to get the potentiometers mounted on to my case. Here is a really embarrasing question :-[

I bought the potentiometers from the BOM but the volume are smaller than the inner plate holes. The pan pots fit fine on the inner panel but I can't figure out how to mount the volume pot. How did you all mount the Potentiometers and what did you use? If you have pictures that would be great!

Thanks
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on May 27, 2016, 02:05:32 AM
Connect them directly to the panel and not to the sub-panel?

I couldn`t fit my meters inside the bracket, so I had to make a bigger hole. Then I realized my pan-pots don`t fit the small panpot holes (not long enough to mount on the helping panel) so I`m either dithching the panel (means I have to glue all the switches to the panel, or use outer washers) or do some serious cutting of the "help panel".
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on May 27, 2016, 02:14:45 AM
Another question:

Routing from ACA/BO and out, here`s how I understand it:

Outputs from ACA goes to the master volume stepped switch. How do they connect? The ELMA switch has an input, output and ground. Each ACA has a balanced output, so +/- and G. I`m guessing G to G  8)  but what about the rest?

Here`s how I imagine I should hook up the rest:

From master switch to l/r booster inputs. Main output from BOOSTER to insert switch relay card input. Send outputs from relay card to one of the "free flying" xlr outputs.
Back from "free flying" XLR inputs to the "Return input" on the relay card. The final Output are the XLR`s soldered to the Relay board.

Secondary outputs from Booster circuit is split in two, one stereo set goes to the alternative outputs (last set of male xlr`s) and one stereo set is sent to the VU Buffer.

Mute switch is connected to the Mute terminals on the 2ACA/BO.


Got everything right?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on May 30, 2016, 05:13:47 AM
Anyone?  :)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: lukas on May 31, 2016, 07:26:42 AM
Look on my post, there is schematic ACA(i think is correct), and mute switch.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ZekeProductions on May 31, 2016, 07:32:32 AM
Anyone?  :)

I wish I had the answer for you since you've always answered me.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on May 31, 2016, 10:07:56 AM
Look on my post, there is schematic ACA(i think is correct), and mute switch.

Yeah, it`s the same from CAPI

http://www.capi-gear.com/catalog/images/gallery/PCBs/2-ACA-Bo/CAPI-2-ACA-Bo-Rev-B.1-schematic.pdf (http://www.capi-gear.com/catalog/images/gallery/PCBs/2-ACA-Bo/CAPI-2-ACA-Bo-Rev-B.1-schematic.pdf)

According to the doc, the insert board should be inserted between the ACA and Booster stages. But since the insert board has the main outs on it (and the DR2402 manual states that the insert board is fed by the Booster), I figured this should be the last stage after the booster outputs. Im also confused by the rotary switch`s "in, out and G(round)" terminals, and what to do when I have a balanced signal coming into this thing. Tie - to ground in the cable, then to the input of the switch? Output to Booster inp? Ground on switch to...?

The mute control is also not totally clear to me. Afaik, the signal is un-muted when  Q2 (?) recieves -16V into one of the Mute inputs (and the other one is ground?). So  -16V to the (top of the) Mute switch on the frontpanel, "wiper" (middle lug) to the signal input on the Mute input of Booster stage, lowest lug to the ground input on the Mute input of the booster stage?  ???

Also, if one wanted some inherent gain in the channels, I guess one might be able to do so by changing some of the feedback resistors? In the 2ACA/BO it would be either R13/R10 or R7/R2? Could it be done on an individual channel basis? I know there aren`t any schem for the DR-2402 (yet?) but I`m guessing it would be easy spotted for the trained eye? Or are the opamps in the DR2402 just used for circuit buffering and have no "gain" in them? Even with my limited knowledge this seems wrong...?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Rocinante on May 31, 2016, 10:48:48 AM
Im just saying something for you to try but iirc wouldn't a switch in that scenario be used like a rheostat?
+ or - in and Ground out then?
Just an idea.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on May 31, 2016, 10:51:15 AM
Im just saying something for you to try but iirc wouldn't a switch in that scenario be used like a rheostat?
+ or - in and Ground out then?
Just an idea.

Talking about the Master rotary, right?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Rocinante on May 31, 2016, 11:22:11 AM
Yeah but I believe we are just agreeing with one another.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on May 31, 2016, 11:52:28 AM
Checked with my multimeter (often helps, this...  ::) ) and the resistance varies between the Input and Output (10k resistance when the fader is down, 0r when the fader is up). Resistance is constant between Input and Ground (10k), and resistance varies between Out and Ground (opposite to how Input does).

So + from ACA output to INPUT on the switch (- shorted to ground on ACA, or at the end of the cable?) ?
Output and Ground on elma to Booster circuit? Then what`s the difference to running ground out from aca to elma?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: lukas on June 01, 2016, 03:17:39 AM
I Just thinking the Capi redrawn ACA from  API console, and ist everything allright(however they works).  On my way this will be something like from  "TheBox" schem. (but maybe different topology).
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: buckethead on June 03, 2016, 11:49:43 AM
I did wire it like in the attached graphic (quick and dirty paint job) ;)
Works like a charm!
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on June 03, 2016, 12:58:26 PM
Shorting - to ground at the end of the cable (just before the switch)? Advantageous contra jumpering at ACA outs?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: buckethead on June 03, 2016, 03:53:38 PM
Not really, connecting the - to GND on the ACA output should work too. The GND layout is not very delicate in this build, you can get away with a lot of messing around ;)

Btw. I just saw I did it exactly the same way Jeff's schematic suggests...
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ZekeProductions on September 12, 2016, 06:57:57 PM
Anyone else finish this yet. I am having issues with mine so far.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: lukas on September 13, 2016, 03:14:59 AM
Yup.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: buckethead on September 15, 2016, 09:32:10 PM
what's the problem?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ZekeProductions on September 15, 2016, 10:17:30 PM
I have populated all the boards and all 28 2520 DOA's. Wired up 2 channel boards (Channels 9-24, I'm working from bottom to top). I've made the PSU also and calibrated the PSU to -/+16v

I power up 1 channel board and send a signal from my DAW to the mixer and no signal passes through the channels. Volume and pan pots do nothing, no led display. 5 mins into testing the channel boards the PSU Capacitors C9 and C10 keep exploding. This happens with any channel board I've tried and I only hook up 1 channel board at a time.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: lukas on September 16, 2016, 04:30:15 AM
Always, when you first run some projects, use bulb serial with 230v power cords. When bulb lights, then soemthing is wrong,  when go off - is ok. On my 2520 boards from kit, i must replace 47pf, at 10pf, and vice versa(i dont forget nr, but they are side by side). Checkout voltage on power, You must swap +-, ...or capacitors voltage are 25v.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: lukas on September 18, 2016, 05:08:44 PM
Shortly.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: DIY-solder on October 08, 2016, 06:54:07 PM
Looks like there are more of these available...   www.diy-racked.com
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: lukas on January 15, 2017, 05:58:40 AM
...if someone wanna make power supply inside mixer i have pcb for them https://groupdiy.com/index.php?topic=64859.0
plus vu meter, and inserts. Monts hole are the same as ACA, from Capi.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on January 15, 2017, 06:18:25 AM
So that`s the insert board + vu buffers + PSU in one board that fits ontop of the aca/bo? Nifty!

I`ve just got my mixer back on my bench after packing my whole studio down and moving to another city (started my career as a commercial diver  8) ) Anyways, pondering on different PSU solutions, as some have reported the current usage of the 2402 is pushing the limit on a single 317/337, and have troubles finding a proper heatsink that matches the PSU pcb layout.

I`ve been thinking about the various JLM psu`s (Kraftwerk, Powerstation 5 and V6) or even going with the easy solution of using this:

http://collectivecases.com/?product=psu-cc-psu1

Altough the last one doesn`t really provide more current than the DR2402 psu.

What do you think?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: lukas on January 15, 2017, 11:40:25 AM
Not necessairly. This psu provide 2x+-16V/2x1.6A(if i good reading),  LM317, and LM337 delivers 1.5A max. I think this is almost the same. Next time i do something like this(adjustable 1,2-32v,/5A) :
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Le Roux on March 12, 2017, 03:05:03 PM
I'm wiring mine and am a bit confused with the ACA inputs/booster inputs and the main volume on/mute switch.

The 3 boards are summed into the ACA input. 
ACA main output to the master volume pot.
Volume pot wired to on/mute switch as in the manual but in stereo
Now this also split off to the booster inputs from volume pot as shown in the attached thanks to buckethead

Main output on booster to relay board.
Multi output on booster to meter buffing board.

Am I correct on all this?

Also on the meter buffering board, I see some jumped the front diodes and removed the 3.3k ohm resistor?  ???
Whats the purpose?

The Relay board is powered from where? Manual says psu but there isn't a dedicated 12V tab or do I just tap off of the 16V?

Thanks
Neil
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on March 14, 2017, 12:06:39 PM
So I got a partial schematic resembling the channel structure sans led-driver on the 2402/1602.

(https://s7.postimg.org/61g0gtsjf/2402_schem.jpg)

So if I am right, this would be a differential amplifier setup for unity gain because R1 = R2 = R3 = R4 (I am going by the designations in the article as explained here:

http://www.electronics-tutorials.ws/opamp/opamp_5.html

(http://www.electronics-tutorials.ws/opamp/opamp18.gif?x98918)

r3/r4 designations are reversed in the DR schem)

So I have a couple of questions:

1) According to the article you can change the amplifiers gain by adding resistors in paralell to r1 and r3.
What resistor values can I use for setting up a channel for say 6 or 12 db gain?

2) If the input is setup for unity gain, will the 1646 actually add 6db`s of gain to the direct output? Why would not a 1640 be used instead?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Andy Peters on March 15, 2017, 03:48:08 PM
So if I am right, this would be a differential amplifier setup for unity gain because R1 = R2 = R3 = R4 (I am going by the designations in the article as explained here:

http://www.electronics-tutorials.ws/opamp/opamp_5.html

(http://www.electronics-tutorials.ws/opamp/opamp18.gif?x98918)

r3/r4 designations are reversed in the DR schem)

So I have a couple of questions:

1) According to the article you can change the amplifiers gain by adding resistors in paralell to r1 and r3.
What resistor values can I use for setting up a channel for say 6 or 12 db gain?

Read further down in that article -- your question is answered there. Use the Differential Amplifier Equation.  And you will need to work the math to convert voltage gain in decibels to the unitless gain. (Hint: 6 dB gain is a gain of two.)

Quote
2) If the input is setup for unity gain, will the 1646 actually add 6db`s of gain to the direct output? Why would not a 1640 be used instead?

Well, if you use a differential receiver that attenuates by 6 dB (please, not "db's of gain"), then you're back to unity.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on March 21, 2017, 04:56:29 AM
Hey Andy, thanks for chiming in!

If I solve the equation with relation to R1/R3, what values should I use for V1/V2 and Vout? I`ve tried solving with an arbitrary 1v for V1 and V2 to find Vout (and then turn it around to find R1 or R3), but not sure if the negative V1 should have negative prefix or not, being a phase inverted input...?

Vout=2000/2000*(1-(-1))
Vout=2v...?

Using +4dbu input signal:

Vout=2000/2000*(1.78-(-1.78))
Vout=3,56V...?

As you mention a gain of 6db is a factor of (almost) 2. So my Vout would be almost the double?

Vout=3,56*1,995262 = 7,1

R3=(R1(V2-V1))/(3.56*1.995262)

R3=(2000(3,56-(-3,56))/(7,1)=2005 ohm? What, in paralell with R3?


Geez. This is all probably wrong so any further guidance would be appreciated!

All the best,

Magnus
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on April 05, 2017, 02:42:29 PM
surely someone have the chops to chime in ?  8)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: metalb00b00 on April 05, 2017, 05:58:42 PM
Vout=2000/2000*(1-(-1))
Vout=2v...?

20K is 20,000 not 2,000

Because R1 = R3 = R2 = R4, then the voltage gain for each amplifier is 1 (or unity gain)

Quote
Using +4dbu input signal:

Vout=2000/2000*(1.78-(-1.78))
Vout=3,56V...?

4dBu is 1.228V not 1.78V

Quote
As you mention a gain of 6db is a factor of (almost) 2. So my Vout would be almost the double?

Vout=3,56*1,995262 = 7,1

Taking what Andy said about 6dB being a factor of two (increase is 2x the voltage, decrease is 1/2 the voltage)

2 = R3/20K
2 = R4/20K

R3 = R4 = 40K
-------------------------------------
0.5 = R3/20K
0.5 = R3/20K

R3 = R4 = 10K

with your 4dBu input signal:
2 x 1.228V = 2.456V (10 dBu)
0.5 x 1.228V = 0.614V (-2dBu)

http://www.mycircuits9.com/2012/06/differential-amplifier-calculator.html
http://www.sengpielaudio.com/calculator-db.htm
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on April 07, 2017, 09:28:46 AM
Thanks so much!

So you could use a DPDT switch to switch between 20k and 40k for r3 and r4.

If you wanted to use a toggle switch for both the muting and the switching of the resistors for an optional +6db gain, looking like this in operation:

3 way toggle switch:
high position: +6db
mid position: unity
low position: mute

what I need is something like a dpdt (for the gain switching) and a spdt (for the mute)? So is that a 3pole 3 way switch? on-on-on?

Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on April 07, 2017, 10:01:58 AM
Or one could integrate it with the volume pot, using a concentric pot with 1k log pot with a 2-position dpdt switch ? Bet that is a way more costly solution... if one were to even find the right product...
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: metalb00b00 on April 07, 2017, 02:52:01 PM
Thanks so much!

So you could use a DPDT switch to switch between 20k and 40k for r3 and r4.

If you wanted to use a toggle switch for both the muting and the switching of the resistors for an optional +6db gain, looking like this in operation:

3 way toggle switch:
high position: +6db
mid position: unity
low position: mute

what I need is something like a dpdt (for the gain switching) and a spdt (for the mute)? So is that a 3pole 3 way switch? on-on-on?

you could just leave it at unity, and add this adjustable 10dB gain circuit before THAT1646.
schematic taken from Mr. Self's Small Signal Audio Design book.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Le Roux on May 08, 2017, 10:31:04 AM
Its together.
Pots were wired backwards even though I followed the Manual, so to add gain I'd turn the volume down...
Fixed

Anyways, I can pass signal to ACA and booster and out, Working

LEDS don't work.
There's only a couple that turn on.
-14.65V when pins are referenced to ground, 0.165V when referenced from pin 1 to pin 2.

I have double checked all resistor values as correct.
It does this on all 3 boards powered separately.
Any ideas?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on May 09, 2017, 01:41:57 PM
Faulty led drivers? Maybe try exchanging the tl074`s that work into a slot that dont work.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Le Roux on May 09, 2017, 07:45:28 PM
The more I try things, the more I'm confused.
Moving opamps will change the voltage at the led.
Most leds are off.
When I turn on power, they flicker as the voltage ramps to 30 some Volts then drops to 0.126V.
Swapped line drivers...nothing.
This is on all three boards
Only thing I haven't confirmed is the diodes uses are in fact the correct ones supplied by mouser.
All resistors confirmed previously but going to reconfirm again.
Voltage at the line driver of 14.65V but gets eaten up by resistors
I'll replace line drivers, and if nothing, I'll breadboard the damn circuit :( lol

Thanks for the advice
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: digrecording on July 21, 2017, 06:52:57 AM
Hi, Long time watcher, first time poster here. I'm building one of these right now and I wanted to share a couple solutions I came up with for the leds and meter mounting.

For the leds I got some small rubber grommets. I believe they are 3/16" id and 1/4" od and jammed them in all the helper panel led holes. I then used a bit of insulation from some  Mogami W2528 cable I had. I just slide a piece of it over the wires to the led and it gives me a nice firm fit with the grommet. Holds well but easy to put in and take out. I'm sure you'd have to experiment with whatever you could get for grommets. Find some insulation that fits well or just build up heat shrink tube until it fits right. I've done that more than once.


https://www.dropbox.com/s/536iqlqax1rc9of/2017-07-21%2002.02.53.jpg?dl=0

https://www.dropbox.com/s/aefdblpqh1pnqzd/2017-07-21%2002.04.42.jpg?dl=0

As for the meters I took my cues from previous posts and fabbed up some little brass flanges. Fortunately I had a 3M - .50 tap handy so I could use regular case screws. The little plastic bits that came with the meters made handy spacers so I could use regular screws while providing a little extra protection for the meter backs.

https://www.dropbox.com/s/rxay0rvl1s46hhh/2017-07-21%2002.05.06.jpg?dl=0

I've got 16 channels running well and hopefully will finish in the next couple weeks. I've taken it down to my studio a couple times to hear it in it's intended environment. It sounds amazing! So much better than our old Neotek IIIc that will be leaving soon. All the other engineers I've demo'd it for have been floored and are bugging me to get it finished so they can use it. Really nice design.


- M
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: hugo on August 10, 2017, 07:55:27 PM
Hi, Long time watcher, first time poster here. I'm building one of these right now and I wanted to share a couple solutions I came up with for the leds and meter mounting.

For the leds I got some small rubber grommets. I believe they are 3/16" id and 1/4" od and jammed them in all the helper panel led holes. I then used a bit of insulation from some  Mogami W2528 cable I had. I just slide a piece of it over the wires to the led and it gives me a nice firm fit with the grommet. Holds well but easy to put in and take out. I'm sure you'd have to experiment with whatever you could get for grommets. Find some insulation that fits well or just build up heat shrink tube until it fits right. I've done that more than once.


https://www.dropbox.com/s/536iqlqax1rc9of/2017-07-21%2002.02.53.jpg?dl=0

https://www.dropbox.com/s/aefdblpqh1pnqzd/2017-07-21%2002.04.42.jpg?dl=0

As for the meters I took my cues from previous posts and fabbed up some little brass flanges. Fortunately I had a 3M - .50 tap handy so I could use regular case screws. The little plastic bits that came with the meters made handy spacers so I could use regular screws while providing a little extra protection for the meter backs.

https://www.dropbox.com/s/rxay0rvl1s46hhh/2017-07-21%2002.05.06.jpg?dl=0

I've got 16 channels running well and hopefully will finish in the next couple weeks. I've taken it down to my studio a couple times to hear it in it's intended environment. It sounds amazing! So much better than our old Neotek IIIc that will be leaving soon. All the other engineers I've demo'd it for have been floored and are bugging me to get it finished so they can use it. Really nice design.


- M

For mine, i plan to use a "safer" solution..i will put pieces of prototyping boards on the rear panel, then i will solder leds to this.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: digrecording on August 15, 2017, 05:42:33 AM
"For mine, i plan to use a "safer" solution..i will put pieces of prototyping boards on the rear panel, then i will solder leds to this."

Fair enuff. I'm a little baffled as to what is "unsafe" about my  idea. There is some shrink tube on the cathode and the outside insulation  is quite thick.

 It seems extremely unlikely that the led could short either to it's self or the case. Unless you were installing or removing it with the unit powered on. That seems like a bad idea however you do it.

Hadn't thought of the proto board thing. Curious to see the execution on that. Seems like that could work well.

- M

Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: hugo on August 21, 2017, 12:40:47 PM
Hi all,
Does somebody know if shielded cable are really important in that build ? In lot of pictures i see a wiring with standard 22awg, and it seems really easier to work with.. So, will i regret to not use shielded cable for Sub d-25 / pan / pot ?
Thanks for the support
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: digrecording on August 24, 2017, 01:25:14 AM
From what I've read shielded is preferable.  In the pan pots the shield carries the signal to the wipers. I used inner cables from a Mogami snake. That way at least there wasn't a thick outer insulator. That stuff is mainly to protect against being walked on which shouldn't be a problem. Just used the drain wire for hookups. Makes things easier.

- M
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: hugo on August 24, 2017, 07:12:30 AM
From what I've read shielded is preferable.  In the pan pots the shield carries the signal to the wipers. I used inner cables from a Mogami snake. That way at least there wasn't a thick outer insulator. That stuff is mainly to protect against being walked on which shouldn't be a problem. Just used the drain wire for hookups. Makes things easier.

- M

Thank you, i finally went with unshielded inputs and shielded for pan/volume.
I also have an optionnal xlr input with sielded cable, so i will be able to compare.
Thank you very much
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on September 08, 2017, 03:11:00 AM
The diy-racked tech recommends swapping the rgulators to lm350t and lm333t. Any merit to this?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: digrecording on September 18, 2017, 11:41:46 AM
Well, I can't speak to how things would go without the switch because I did the switch when I only had 8 channels running but I can say that after a couple months of being finished and in service in my studio I have had exactly zero problems with power.  I love zero problems.

My understanding is the 1.5a ones are kind of borderline enough power. Depending on op amp selection you could wind up pushing that. With the 3a you have headroom. Could probably drive a headphone amp off of it as well without trouble.

- M
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on September 19, 2017, 08:42:06 AM
You mean youve only ever used it with the 333/350? I was under the impression that the power problems were due to the regulators overheating, not going over spec amperewise... so, the regulators being same package and used with the same heatsinks, i would think they would heat up just the same. But ill give it a go :)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: digrecording on September 20, 2017, 11:48:09 AM
I think it stands to reason that a regulator near it's limit will get hotter than one in the middle of it's range. Also I did use the biggest heat sinks I could find that would fit in the external box.

http://www.mouser.com/Search/ProductDetail.aspx?R=531302B02500Gvirtualkey53210000virtualkey532-531302B25

I made sure to use thermal grease with them and all that having read about some of the heat problems people were having. It does get kinda warm. I'm sure if it were at my house I'd have trouble keeping my cat off it but it's not alarmingly warm and has been super reliable sometimes being on for days at a time.

- M
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on September 22, 2017, 02:47:35 AM
I am presuming that to make the direct outs be post fader, i can just connect the toop of the 10k resistor to the left side of one of the pan resistors?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Floti on September 22, 2017, 03:47:13 AM
that should work
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: digrecording on September 25, 2017, 05:14:00 AM
I actually put in a switch. It was a crazy idea and retrofitting it is no fun. Fortunately I only had to do that to the first 8. Honestly I don't know if I'll ever use it but I can see advantages to having it both pre and post. Obviously this is not a quick flip solution but if you decided you wanted to change your configuration you could open things up and just throw a switch.

https://www.dropbox.com/s/dro1n81u8a9u9f0/Switch%20assembly.jpg?dl=0

https://www.dropbox.com/s/m9i2u5e1b5isuc5/Switch%20installed.jpg?dl=0

I used these guys because they were cheap and seemed like they would fit. Luckily enough they did.

http://www.mouser.com/Search/ProductDetail.aspx?R=EG1218virtualkey61200000virtualkey612-EG1218

I don't really know if this is advisable. I'm no electronics engineer by any stretch but when I tested it I couldn't hear or measure a difference between pre and post positions as far as the output is concerneed. No smoke came out so I'm calling that a win.

I haven't even got the direct out molex to db25's wired yet but I had a deadline so for now it just doesn't have dir outs and no one really cares but I'll get em' installed eventually.



Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on September 25, 2017, 06:11:03 AM
Yeah, my original plan was to incorporate the mute switch into a switched potentiometer, and use the switch cutout for pre/post selection. But it became too time consuming, and i am going to build an aux send module that is inserted before the dr2402, leaving the direct outs from the 2402 to be used strictly as a recorder send. Hence ill only need post sends ;)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: digrecording on September 26, 2017, 03:21:45 AM
Heh, yeah. I thought of doing the same thing, and came to the same conclusion. "Do I want to spend a month wiring point to point?" No.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: hugo on October 20, 2017, 06:27:37 AM
"For mine, i plan to use a "safer" solution..i will put pieces of prototyping boards on the rear panel, then i will solder leds to this."

Fair enuff. I'm a little baffled as to what is "unsafe" about my  idea. There is some shrink tube on the cathode and the outside insulation  is quite thick.

https://www.dropbox.com/s/alvo5yloblt6bwy/2017-07-21%2001.57.11.jpg?dl=0

 It seems extremely unlikely that the led could short either to it's self or the case. Unless you were installing or removing it with the unit powered on. That seems like a bad idea however you do it.

Hadn't thought of the proto board thing. Curious to see the execution on that. Seems like that could work well.

- M
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: hugo on October 25, 2017, 09:22:43 AM
Hi,

all leds are only red when signal is sent to the mixer...whereas i ordered green/red leds...How to correct this ?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: buckethead on October 27, 2017, 10:08:39 AM
Hi,

all leds are only red when signal is sent to the mixer...whereas i ordered green/red leds...How to correct this ?

Flip the polarity of the leds?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: hugo on October 28, 2017, 03:39:27 PM
Flip the polarity of the leds?

Yes i did, all works good now :-)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Potato Cakes on November 12, 2017, 06:54:19 PM
For those with completed builds, do you have any pertinent measurements you would like to share? I'm on a search what I should do for a summing mixer build (or just keep my Mixdream XP) and I'm curious about the 2402's performance (frequency response, transient response, etc.) and if there are any comparisons to other notable analog mixers that would be worth taking into consideration. I know that the selection of DOAs will affect these measurements, but I'm hoping to get an overall idea of what I could expect. To go this route would require some considerable work to integrate it, but if this aids significantly to yielding a better product for clients, then it's worth it to me.

Thanks!

Paul
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: hugo on November 19, 2017, 04:50:53 PM

I finished mine, what you should except is very clean sound, no coloration..it makes its summming job great...
but of course, even just one cap or one tube on a compressor will add much more color, so just expect good analog summing, it is not a magical box who changes a bad mix to a top notch one..but it is a great heart for a good studio. Also, it is not a cheap project at all, be ready to do metal work, and to find your own way for some mounting... I'm happy with mine, but i would not build a new one and if i build a new studio, i would consider the summing at the end...Hard to recognize this, but my 500eu ssl bus comp on parallel is more useful to improve a mix..than every summing (my daw summing is not so far from my analog summing,  i can not make the difference on a blind test)..
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: hugo on November 23, 2017, 01:30:32 PM
Just to know...i have to see like "+2db" on my DAW to clip one channel of the summing mixer..is it normal ?
Should i have the clipping led illuminated at lower level ?
Regards,
Hugo
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Potato Cakes on November 23, 2017, 03:16:39 PM
I finished mine, what you should except is very clean sound, no coloration..it makes its summming job great...
but of course, even just one cap or one tube on a compressor will add much more color, so just expect good analog summing, it is not a magical box who changes a bad mix to a top notch one..but it is a great heart for a good studio. Also, it is not a cheap project at all, be ready to do metal work, and to find your own way for some mounting... I'm happy with mine, but i would not build a new one and if i build a new studio, i would consider the summing at the end...Hard to recognize this, but my 500eu ssl bus comp on parallel is more useful to improve a mix..than every summing (my daw summing is not so far from my analog summing,  i can not make the difference on a blind test)..

Thanks for the info.

I agree that analog summing should not be looked at as a magic box that will magically undo bad mixing techniques, but I have done blind tests with and without and the client has always picked the analog summing version, so I always choose that option. And I guess the other thing is evaluating is it worth selling my Mixdream XP and building either the 24 or 16 channel version of this unit and after all the extra work end up sonically where I started. I'll probably just put this project way down the list for something to do when on a very long tour.

Thanks!

Paul
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: hugo on November 24, 2017, 04:06:53 PM
I am a little bit worrying about noise...i dont know what is normal noise level there. I mean, with all channels muted...Anybody ?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: digrecording on December 12, 2017, 01:33:22 PM
I've had mine up and running since June. I'm actually amazed at how quiet it is. That's with all 24 channels enabled and faders all the way up. I don't have any actual measurements (will try to run some when I get a chance) but with it hooked up to the 24 outs of my Symphony i/o and running through my Sound Skulptor MC624 master section turned all the way up I have a hard time telling the difference between muted and un muted. I've worked with several of the legendary large format consoles in my time and the DR-2402 is by far the quietest mixer I've ever used.

I'm very interested in all the different op amp flavors out there. One of the really cool things with the 2402 is the ability to load it up with different pairs of op amps. You can then take a stereo mix and easily compare pairs of different op amps by just switching your output.  Right now I have it loaded with stock API 2520s on 1-2, Scott Lieber Red dots on 3-4, A pair of op amps recommended by Tat with nos can transistors (very nice) on 5 - 6, and a pair of the Sound Skulptor 2520s on 7 - 8. The rest of the channels are APP992s (also very nice) and the summing board is API 2520s. I've been planning to write an article on my observations of the various flavors but I type kind of slow and have been too busy recording lately to do much else.

My studio partner also has a nice home setup with 24 channels of API 8200 into a 7800 master section and he has raved many times to me about how remarkably similar the 2402 sounds and how nice it is to have such a similar sound at both locations.

To be sure, I would not recommend this project for beginners. You're going to need good electrical and mechanical instincts to complete one of these. It is not "everything you need in one box" like the CAPI or Sound Skulptor kits. That said I am super happy with mine and had a lot of fun building it. It wasn't cheap but I'm not looking to sound cheap and it was still considerably less than similar products (Neve 8816, Burl Vancouver, API8200) while providing a lot more flexibility.

Admittedly I am a tinkerer and love fixing, modding and building my own gear. Many of the mass produced options out there are mostly smd and god help you if you want to work on them without full schematics and good smd skills.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: hugo on December 15, 2017, 03:33:34 AM
I've had mine up and running since June. I'm actually amazed at how quiet it is. That's with all 24 channels enabled and faders all the way up. I don't have any actual measurements (will try to run some when I get a chance) but with it hooked up to the 24 outs of my Symphony i/o and running through my Sound Skulptor MC624 master section turned all the way up I have a hard time telling the difference between muted and un muted. I've worked with several of the legendary large format consoles in my time and the DR-2402 is by far the quietest mixer I've ever used.

I'm very interested in all the different op amp flavors out there. One of the really cool things with the 2402 is the ability to load it up with different pairs of op amps. You can then take a stereo mix and easily compare pairs of different op amps by just switching your output.  Right now I have it loaded with stock API 2520s on 1-2, Scott Lieber Red dots on 3-4, A pair of op amps recommended by Tat with nos can transistors (very nice) on 5 - 6, and a pair of the Sound Skulptor 2520s on 7 - 8. The rest of the channels are APP992s (also very nice) and the summing board is API 2520s. I've been planning to write an article on my observations of the various flavors but I type kind of slow and have been too busy recording lately to do much else.

My studio partner also has a nice home setup with 24 channels of API 8200 into a 7800 master section and he has raved many times to me about how remarkably similar the 2402 sounds and how nice it is to have such a similar sound at both locations.

To be sure, I would not recommend this project for beginners. You're going to need good electrical and mechanical instincts to complete one of these. It is not "everything you need in one box" like the CAPI or Sound Skulptor kits. That said I am super happy with mine and had a lot of fun building it. It wasn't cheap but I'm not looking to sound cheap and it was still considerably less than similar products (Neve 8816, Burl Vancouver, API8200) while providing a lot more flexibility.

Admittedly I am a tinkerer and love fixing, modding and building my own gear. Many of the mass produced options out there are mostly smd and god help you if you want to work on them without full schematics and good smd skills.

Hi, thank you for your feedback. You can not compare it to a console, since the "0" is achieved when all pots are fully CW...so it does not add gain to the signal, just the possibility to attenuate it. My unit seems to work good, but i never know since no measurement out there..
In your DAW, what is the level for the signal you send to the mixer ? At which level you have the leds becoming red ? My daw peaks before my summing mixer, is it normal ?
When the signal return to your daw, which level do you have ?
Thank you
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: JessJackson on December 18, 2017, 02:50:49 AM
I need some help with mine, who's in LA?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: MrBlomski on January 19, 2018, 07:37:45 AM
I'm very interested in all the different op amp flavors out there. One of the really cool things with the 2402 is the ability to load it up with different pairs of op amps. You can then take a stereo mix and easily compare pairs of different op amps by just switching your output.  Right now I have it loaded with stock API 2520s on 1-2, Scott Lieber Red dots on 3-4, A pair of op amps recommended by Tat with nos can transistors (very nice) on 5 - 6, and a pair of the Sound Skulptor 2520s on 7 - 8. The rest of the channels are APP992s (also very nice) and the summing board is API 2520s. I've been planning to write an article on my observations of the various flavors but I type kind of slow and have been too busy recording lately to do much else.

Already wrote it?
Currently finishing mine after a couple of years :)
I am gonna build another PSU for it in the futher. Quieter and better.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ZekeProductions on February 20, 2018, 08:11:19 PM
I started this project approx. 18 months ago I had bought all the parts (even some spare parts just in case) soldered all the opamps, all the boards, mounted vu meters, but ran into a little trouble with the wiring and sort of gave up as I had purchased the API DSM24 summing mixer for a too good too be true offer.

I still have this project on my desk and it haunts me everyday. I don't know whether to finish it or sell it as is. Anyway Does anyone have any good pictures of how they wired theirs? I am not sure how the wiring goes.

Also has anyone fixed the PSU heating issue? Thanks for your help
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: qmp audio on February 21, 2018, 12:59:49 AM
Also has anyone fixed the PSU heating issue? Thanks for your help

This is from Facebook:

“DR-2402 API SUMMING MIXER UPDATE - PSU OVERHEATING ISSUE
Use the 3A regs LM350T & LM333T !
They are available on ebay “
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ZekeProductions on February 21, 2018, 12:05:51 PM
This is from Facebook:

“DR-2402 API SUMMING MIXER UPDATE - PSU OVERHEATING ISSUE
Use the 3A regs LM350T & LM333T !
They are available on ebay “

Has anyone tried that and found that this was the solution? I'd like to know before spending more money.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: MrBlomski on February 21, 2018, 12:33:09 PM
Not yet, by 1.5 amps is no power headroom so to speak.
I am going to make a whole other power supply.  Higher amp and quieter.

Btw. Wiring is in the manual.
If you want I can make some pictures. I am continue the build after a year. Almost done.  :)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ZekeProductions on February 21, 2018, 07:08:51 PM
Not yet, by 1.5 amps is no power headroom so to speak.
I am going to make a whole other power supply.  Higher amp and quieter.

Btw. Wiring is in the manual.
If you want I can make some pictures. I am continue the build after a year. Almost done.  :)

That would be great, Thanks!

I'm going to read the manual again and see what i did wrong.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ZekeProductions on March 06, 2018, 11:40:48 PM
This is from Facebook:

“DR-2402 API SUMMING MIXER UPDATE - PSU OVERHEATING ISSUE
Use the 3A regs LM350T & LM333T !
They are available on ebay “

Does the LM350T replace the 337 & the LM333T replace the 317??
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ZekeProductions on March 17, 2018, 03:48:01 PM
Anyone know the answer to my above question???
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ZekeProductions on March 17, 2018, 03:49:02 PM
Not yet, by 1.5 amps is no power headroom so to speak.
I am going to make a whole other power supply.  Higher amp and quieter.

Btw. Wiring is in the manual.
If you want I can make some pictures. I am continue the build after a year. Almost done.  :)

Any luck on getting yours up and running? Were you able to get some wiring pics?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: digrecording on April 29, 2018, 12:30:28 AM
Just a quick post about the power supply. The LM333t replaces the 337 (neg) and the LM350t replaces the 317 (pos)

These work great in the power supply. I also got the biggest heat sinks that will fit in the box (external)

https://www.mouser.com/ProductDetail/532-531302B25?R=531302B02500Gvirtualkey53210000virtualkey532-531302B25

Used a little thermal grease just in case.

As for the wiring I noticed a couple things that were incorrect. If you wire the volume pots like the manual they will behave backwards. Also be sure to wire the wiper to the mute switch and make sure you are grounding the pcb side when the mute is engaged. Otherwise you're sending the output of the op amp to ground and they get hot fast (personal experience, fortunately didn't fry any)

Also I had to wire my signal leds the opposite of the manual. I don't know if this is a variation in the leds or an error in the manual.

Hope this helps. Mine has been up and running great for almost a year now. Totally love it. Feel free to pm me if you have other questions.

Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: MrBlomski on April 29, 2018, 01:10:36 AM
Led is reversed Yes

Volume, maybee you where thinking from front panel view point?

As for the mute switch; you mean the thirt solder lug of the toggle switch to ground?

Cheers.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on April 29, 2018, 12:42:41 PM
a quick new wiring diagram with the needed changes would be appreciated, nice to have it all in one place since DIYracked won`t update their own manual
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: digrecording on May 01, 2018, 05:08:31 AM
Led is reversed Yes

Volume, maybee you where thinking from front panel view point?

As for the mute switch; you mean the thirt solder lug of the toggle switch to ground?

Cheers.

To be fair the volume pot diagram does specifically say "VOLUME POT(FRONT VIEW)" So I assumed that meant looking at the shaft side of the pot, the drawing also looks like that side.  From that perspective turning the pot all the way up connects the wiper to ground (pin 2 being ground) no sound getting through there. If you treat it like you're looking at the back of the pot it's correct.

As for the switch, that is correct on the diagram. Sorry if I was unclear on that. I accidentally wired a couple so the wiper rather than pin 3 was connected to ground in the mute position. Made for a hot op amp. That was more of a "Don't do this dumb thing I did" not a problem with the diagram.

With a couple notable exceptions(led and volume pot) the instructions are quite good. They are not holding your hand here. It's pretty sparse. That said all the other troubles I had were mistakes I made, once corrected I've had great success with this box. It's been super reliable and sounds just great.



Cheers
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: echoplex on June 08, 2018, 01:08:27 PM
any further thoughts here?

how does this unit really sound? has it anything to do with the old API vintage desk sound, which everybody loves?
I am about to pull the trigger on this one but can't barely find any user experience in terms of sonic performance and sound.

thanks  :)
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: digrecording on June 08, 2018, 03:27:03 PM
It's very transparent. Not a total color bomb. If you run a stereo mix across it the difference between that and the direct line is pretty subtle. Where it shines is when you start throwing a lot of channels at it. Mixes that sound crowded and 2 dimensional in the box open up and breathe. The op amps and transformers have a subtle sweet dynamic control that just sort of squeezes everything to the 2 bus so it all fits.

My studio partner has a pretty extensive home studio  with 24 channels of API 8200 feeding an API 7200 master section. He was really happy when I installed this "Finally things sound the same downtown as at home!" To be fair he also really wasn't fond of the Neotek 3c console that it replaced. Rightly so, comparing the two a/b was night and day. The 2402 was so much cleaner and more open sounding with vastly improved stereo imaging and stronger tighter bass response.

Op amp selection does make a difference. Again, it's subtle but one of the things I like about it is the ability to quickly a/b op amps by arranging them in stereo pairs. I'm using APP992 op amps in 1-16. I have stock API 2520s in the master section and stereo pairs of some some other DOAs in 17-24.  For example listening to a stereo mix through my API 2520 pair (17-18) I find it has the classic 2520 kind of mid forward sound with lots of detail and a bit of subtle crunch when pushed. By contrast the APP992s sound cleaner to my ears with more extended highs and lows than 2520s and a smoother mid response. The differences are subtle enough that I'm not sure I'd notice them if I had to pause for a few minutes to swap things out but when you can flip back and forth just by changing your DAWs output the difference is pretty noticeable.

I've never had the pleasure of mixing on a vintage API board but it's my understanding that they have a vary similar sound. Thanks in large part to the CAPI ACA summing section. That is as true to the original circuit as is possible with modern components from what I've read.

I'm not claiming any great expertise in this area. I'm sure there are some gaping holes in my knowledge about the fine points. I have however built a 2402 that sees daily use from myself, my business partner and a few freelance engineers. I know that it has made outboard summing converts of a couple of our freelancers who previously had been strictly "in the box" guys. It's worked to my benefit because they are booking extra time to bring their mixes in from home and spread them out across the 2402.

Hope this helps.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: MrBlomski on June 09, 2018, 02:08:45 AM
Nice story!
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: echoplex on June 09, 2018, 08:28:16 AM
thanks for your report :)

Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ZekeProductions on June 11, 2018, 10:02:07 AM
If you are interested, I'm selling mine as I seem to never have time to finish building this. I'm giving up on it as I have a API DSM 24 and it is banging!

https://groupdiy.com/index.php?topic=68964.0

https://reverb.com/item/7064720-dr-2404-blue-api-like-summing-mixer


Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: echoplex on June 12, 2018, 04:27:16 PM
Hi guys,

I have a number of questions because some things are very unclear for me from the provided BOM.

Position 19 in the BOM: it just says BI POLAR ELECTROLYTIC CAPACITORS 22uF and AUDIO as a note.
What should I use here? Maybe someone can directly link me to mouser.

Position 28: unfortunately unavailable at mousers. Can anyone link me a alternative?

Further I need those sub-d connectors, spacer bolts, nuts and those two XLR connectors for the insert-board.
Any links are very much appreciated  :-*
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: qmp audio on June 12, 2018, 04:39:43 PM
Hi guys,

I have a number of questions because some things are very unclear for me from the provided BOM.

Position 19 in the BOM: it just says BI POLAR ELECTROLYTIC CAPACITORS 22uF and AUDIO as a note.
What should I use here? Maybe someone can directly link me to mouser.

Position 28: unfortunately unavailable at mousers. Can anyone link me a alternative?

Further I need those sub-d connectors, spacer bolts, nuts and those two XLR connectors for the insert-board.
Any links are very much appreciated  :-*

22uf bipolar: https://www.mouser.com/ProductDetail/647-UES1E220MEM?R=UES1E220MEMvirtualkey64700000virtualkey647-UES1E220MEM

2 in 3.96 pitch:  https://www.mouser.com/ProductDetail/Molex/09-65-2029?qs=%2fha2pyFaduhbbRpAVeK0W9%252bQvgy3yg8Lvpv%252bHjOos7Lwo6RevUeJbQ%3d%3d

i usually source connector parts form redco.com

Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: echoplex on June 12, 2018, 05:44:12 PM
thanks a lot mate!
and lastly, I forgot:

the PSU BOM: Position #2: 5k Trim Pot.
there are hundrets of 5k trimpots on mousers.. which one to take?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: qmp audio on June 12, 2018, 06:20:08 PM
no problem.   The short answer is whichever one you want.   you want a Bournes trimmer resistor. 


i dont have record of what i got, and dont have that PSU.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: echoplex on August 10, 2018, 05:11:34 AM
Regarding the PSU...
I am having hard times sourcing a LM333 voltage regulator.
Is there any alternative to this that I could use?

I was told to use (other than written in the BOM): LM350 instead of LM317 and LM333 instead of LM337
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: ZekeProductions on August 10, 2018, 11:19:49 AM
You should try the link below. they ship worldwide. I got mine from ebay too as they are hard to find. they do work better than what's in the BOM

https://www.ebay.com/itm/NS-TO-220-3-Ampere-Adjustable-Negative-Regulators-LM333T/401213587079?epid=780636182&hash=item5d6a317e87%3Ag%3AAvIAAOSwo4pYD2jY&_sacat=0&_nkw=lm333+voltage+regulators&_from=R40&rt=nc&LH_TitleDesc=0


Edited: I put the wrong link in at first. The right link is above.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: echoplex on August 10, 2018, 02:53:45 PM
Thank you Zeke!
However they charge 20$ for shipping to Europe. Thats quite heavy for a tiny single component.
If anyone has a spare LM333, I'd appreciate very much
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: Kevin on November 11, 2018, 11:05:19 AM
Is there any shematic of the main board? I can't find any shematic of this pcb board in the documents of diy racked. Just overview and bom. But i need a schematic of this design. Does anyone have this shematic?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: hugo on December 18, 2018, 09:25:41 AM
Does somebody measure the noise of this ?
Mine approach -64dbfs with all channels muted and output volume at maximum (analog to +24db interface) .. Is it called "low noise" for a summing mixer ?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: hugo on December 29, 2018, 07:46:06 PM
Hi,
Does anybody have a wiring diagram for the ground with a separate PSU ?
I can not figure if there are 2 stars grounds, do i use the shield of the psu cable ?..
Thx
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: lukas on December 30, 2018, 06:13:58 AM
...maybe it will help?
 https://drive.google.com/open?id=1dEL59IjF45ehID_LV9dvuTsgAIyR2R-s
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: hugo on December 31, 2018, 04:54:31 PM
Thank you but the manual don’t show if there are 1 or 2 star grounds (one for the psu, one for the unit).
On my unit, I reduced my noise by making like this :
- solder small pads on the psu board to have the ground passing through the pcb
- star ground on psu, at corner of pcb, connected to the iec inlet ground and to the pcb ac ground.
- psu xlr ground connected to dc ground of pcb

On the unit, I putted my star ground at the corner of the aca board, marked « ground ».
- this star ground is connected to the ground pin of the xlr Input  from psu, and to the channels boards grounds.
-regarding the manual, I removed the ground wire sitting between the +16v and the -16v of aca board because it is connected by the pcb to the star ground (at the corner of the same pcb)

With this I don’t have 2 points of ground connected together on multiple spots...

I don’t hear noise but my fabfilter eq shows -78dbfs in my daw (audio converters settings : +20db)
Is it a good noise level for this project or is there anything to make it even lower ?

Also, what is the 0 point at the output pot ? I have no gain/no loss with output about 4  o’clock..normal ?

Thank you
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: hugo on January 21, 2019, 10:00:29 AM
Completed with a nice grounding / vu meter setted in Db VU
Everything works awesome, -90dbfs on my daw, no distortion.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: TillM on January 21, 2019, 04:24:07 PM
Hi Hugo,
what kind of DOAs are you using ?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on February 14, 2019, 02:36:44 PM
Oh man getting close now. After a long hiatus I`ve spent the last few days wiring this beast up. Powersupply is up and running, and most of the mixer wired up. Missing a couple of resistors for the aca/bo in order for the first power-up to take place...

I work shift ofcourse, so will be another couple of weeks before I have the time to finish it up, but it really feels in reach now. So looking forward to putting this to good use!
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: hugo on February 23, 2019, 02:01:00 AM
Oh man getting close now. After a long hiatus I`ve spent the last few days wiring this beast up. Powersupply is up and running, and most of the mixer wired up. Missing a couple of resistors for the aca/bo in order for the first power-up to take place...

I work shift ofcourse, so will be another couple of weeks before I have the time to finish it up, but it really feels in reach now. So looking forward to putting this to good use!

Hi. Did you test one single channel ? Before having to swap one wire on all channels..
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on February 27, 2019, 02:27:13 PM
Not yet. Isn`t the manual updated to be correct by now? Anyways, Ill be sure to try one channel first. Hopefully it`s wired right  8) (afaik the confusion stems from the volume pot having bottom and top terminals confused in the manual. That and the LED wiring is the wrong way around...?)

A little confusion around switches. As far as I understand "on - none - on" means that there is no center position for the toggle? Aka suitable for both the stereo channels mute switches and the main power switch.

I was hoping to use an illuminated switch for the +/- 16V, but am struggling to find one.
I`ve found this:

https://no.mouser.com/ProductDetail/NKK-Switches/M2122TCG01?qs=sGAEpiMZZMvudeGI7i40XMgdnVkjSffTQp%2F%2Fw8MWVxo%3D

but according to the data sheet, under "Contact materials and ratings", it`s marked as "G" aka Gold: "Rated 0.4VA max @ 28V AC/DC max" so probably not suitable? Being that the DR2402 will be drawing about 1.5 amps?
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on February 27, 2019, 02:32:14 PM
oh yeah and here`s the switch I`m about to order for the stereo mutes:

https://no.mouser.com/ProductDetail/612-100-F1111
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: fragletrollet on March 12, 2019, 10:32:03 AM
Okay so first power-up worked fine. So far I haven`t run more than one board, and with its 8 opamps + 4 in the aca/bo section, my psu allready seems to be working pretty hard, as the heatsinks (the biggest that could physicly fit inside the psu enclosure) are getting quite hot (too hot to hold your finger on for more than a few seconds). Wondering how it`ll keep up when I add the remaining 16 opamps!

It sounds good and clean when running music through it. I am however experiencing some hum when all faders are wide open. Wondering how you are doing your noise measurements? This might be down to my at this point rudimentary cabling, will do some more testing before I "decide" it`s hum I hear, and just not the background noise. I mean, it`s right down levelwise with what I believe would be crosstalk (that I presume is the leakage of the channel I hear when the channel is muted but main fully open, and monitoring turned way up).

Also wondering on what level the LED`s turn red. They work fine and respond to the level by going from unlit to greenly lit, but I presume my Babyface pro doesn`t go loud enough to pass the "red threshold", as I`ve only tested it unbalanced where the max output of the RME is +13dBu (the mixer will be used with SSL converters in the future, which are 22dBu maximum i/o). The main xlr outs on the RME are +19dBu, I`ll give them a shot as soon as I`ve got the right cabling at hand (my whole studio is packed down at the moment, still trying to find a new nice space for it).

Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: hugo on March 15, 2019, 08:14:05 AM
Hum is not normal, i never experienced any hum in this design, you have a ground loop. Check contact between all panels. Put your star ground at the corner of the aca board, called "gnd", to avoid multiple connections to the chassis. Pots does not influence the noise level in my build; full open or closed, i still get -90dbfs on my daw. With my audio interface setted up +18db, leds become red about -2dbfs on my daw, but it depends on the sound used..more bass take more level... check grounding and output transformers wires place. Keep them far from any psu cable. Its the best summing mixer ever, after testing few of them. Clean wiring is mandatory. Shielded wires for all pots, not needed for rear panel connections.
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: discord on August 30, 2019, 04:53:39 PM
Would anyone be so kind as to post a picture of their completed power supply? I'm not certain I ordered the correct parts based on how they are fitting on the PCB. Specifically need to see "AC", "B1", and "DC". I'm also curious which trimpots to use. Would these be ok? https://www.mouser.com/ProductDetail/Bourns/3296W-1-502LF?qs=sGAEpiMZZMukHu%252BjC5l7YWXS5CHXEyUCH3WN4C%252BSmS0%3D

Thanks in advance!
Title: Re: 24ch API SUMMING MIXER DR-2402
Post by: discord on September 02, 2019, 11:30:32 AM
Nevermind. All set now.

For anyone else confused by the 2402 BOM with no part numbers, look at the BOM for the DR-NEQ3D because it actually has the part numbers listed.