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 »
What you have sounds pretty good....Until you hear bettter

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

What you have sounds pretty good....Until you hear bettter