digrecording

Re: 24ch API SUMMING MIXER DR-2402
« Reply #180 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.

The funny thing about regret is that it's better to regret something that you have done than to regret something you haven't done.


MrBlomski

Re: 24ch API SUMMING MIXER DR-2402
« Reply #181 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.

Re: 24ch API SUMMING MIXER DR-2402
« Reply #182 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

digrecording

Re: 24ch API SUMMING MIXER DR-2402
« Reply #183 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
The funny thing about regret is that it's better to regret something that you have done than to regret something you haven't done.

Re: 24ch API SUMMING MIXER DR-2402
« Reply #184 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  :)

digrecording

Re: 24ch API SUMMING MIXER DR-2402
« Reply #185 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.
« Last Edit: June 08, 2018, 03:30:28 PM by digrecording »
The funny thing about regret is that it's better to regret something that you have done than to regret something you haven't done.

MrBlomski

Re: 24ch API SUMMING MIXER DR-2402
« Reply #186 on: June 09, 2018, 02:08:45 AM »
Nice story!

Re: 24ch API SUMMING MIXER DR-2402
« Reply #187 on: June 09, 2018, 08:28:16 AM »
thanks for your report :)

« Last Edit: June 11, 2018, 05:24:04 AM by echoplex »

Re: 24ch API SUMMING MIXER DR-2402
« Reply #188 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



Re: 24ch API SUMMING MIXER DR-2402
« Reply #189 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  :-*


qmp audio

Re: 24ch API SUMMING MIXER DR-2402
« Reply #190 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


Re: 24ch API SUMMING MIXER DR-2402
« Reply #191 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?

qmp audio

Re: 24ch API SUMMING MIXER DR-2402
« Reply #192 on: June 12, 2018, 06:20:08 PM »
no problem.   The short answer is whichever one you want.   you want a Bournes trimmer resistor. 

  • looking at the outline of the psu in the pdf,  looks like it is vertical adjust ( the trimmer adjustment is on top, instead of side )
  • you'll want to look at the PCB and determine if the leads are straight in line (W) or offset (Y).
  • youll need to do a little math (ohms law) to determine what power rating is needed.
  • also you can decide the tolerance you want and how many rotations you want.   the more rotations,  the easier it is to fine adjust things.

i dont have record of what i got, and dont have that PSU.
« Last Edit: June 12, 2018, 07:07:37 PM by qmp audio »

Re: 24ch API SUMMING MIXER DR-2402
« Reply #193 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

Re: 24ch API SUMMING MIXER DR-2402
« Reply #194 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.
« Last Edit: August 10, 2018, 11:40:48 AM by ZekeProductions »

Re: 24ch API SUMMING MIXER DR-2402
« Reply #195 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

Kevin

Re: 24ch API SUMMING MIXER DR-2402
« Reply #196 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?