Re: 24ch API SUMMING MIXER DR-2402
« Reply #140 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.


Le Roux

Re: 24ch API SUMMING MIXER DR-2402
« Reply #141 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?

Re: 24ch API SUMMING MIXER DR-2402
« Reply #142 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.

Le Roux

Re: 24ch API SUMMING MIXER DR-2402
« Reply #143 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

digrecording

Re: 24ch API SUMMING MIXER DR-2402
« Reply #144 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
« Last Edit: August 02, 2017, 05:14:34 AM 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. - Wisdom from the Butthole Surfers

hugo

Re: 24ch API SUMMING MIXER DR-2402
« Reply #145 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.

digrecording

Re: 24ch API SUMMING MIXER DR-2402
« Reply #146 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.

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

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. - Wisdom from the Butthole Surfers

hugo

Re: 24ch API SUMMING MIXER DR-2402
« Reply #147 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

digrecording

Re: 24ch API SUMMING MIXER DR-2402
« Reply #148 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
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. - Wisdom from the Butthole Surfers

hugo

Re: 24ch API SUMMING MIXER DR-2402
« Reply #149 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


Re: 24ch API SUMMING MIXER DR-2402
« Reply #150 on: September 08, 2017, 03:11:00 AM »
The diy-racked tech recommends swapping the rgulators to lm350t and lm333t. Any merit to this?

digrecording

Re: 24ch API SUMMING MIXER DR-2402
« Reply #151 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
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. - Wisdom from the Butthole Surfers

Re: 24ch API SUMMING MIXER DR-2402
« Reply #152 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 :)

digrecording

Re: 24ch API SUMMING MIXER DR-2402
« Reply #153 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
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. - Wisdom from the Butthole Surfers

Re: 24ch API SUMMING MIXER DR-2402
« Reply #154 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?

Floti

Re: 24ch API SUMMING MIXER DR-2402
« Reply #155 on: September 22, 2017, 03:47:13 AM »
that should work

digrecording

Re: 24ch API SUMMING MIXER DR-2402
« Reply #156 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.



« Last Edit: September 25, 2017, 05:25:39 AM 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. - Wisdom from the Butthole Surfers

Re: 24ch API SUMMING MIXER DR-2402
« Reply #157 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 ;)

digrecording

Re: 24ch API SUMMING MIXER DR-2402
« Reply #158 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.
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. - Wisdom from the Butthole Surfers

hugo

Re: 24ch API SUMMING MIXER DR-2402
« Reply #159 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