[Build] CAPI Summing Mixer ~ SumBus ACA ~ Official Support Thread

[jsteiger]

I'm considering building this soon. Can anybody point me in the direction of some audio samples? I'd love to hear some music summed itb compared to the CAPI Sumbus. If you have one, would you be willing to post or send me something? Thank you!

Here's a few off the top of my head.

https://youtu.be/tNkQpLKYmlM

https://youtu.be/HDAKS18Gv1U

https://youtu.be/fJYPJNJzSoo

 

[downbytheriver]

Did the sumbus1 at the start of this thread with faders and pan ever get released?
thanks!

 

[jsteiger]

Did the sumbus1 at the start of this thread with faders and pan ever get released?
thanks!

I have never released that version. Its a pretty large undertaking that we haven't had the extra time/money to work on. I am thinking about tackling it this year though.

 

[jasonallenh]

I have never released that version. Its a pretty large undertaking that we haven't had the extra time/money to work on. I am thinking about tackling it this year though.

Still thinking about this

 

[mikael__]

I have never released that version. Its a pretty large undertaking that we haven't had the extra time/money to work on. I am thinking about tackling it this year though.

Hi Jeff,
Any update regarding this ?

 

[JMan]

I would also like to see that become available!

 

[jsteiger]

We have not had the time over the past 8 months to sort all of the parts for the pushbutton version so haven't even thought about the rotary controlled version.

 

[JMan]

We have not had the time over the past 8 months to sort all of the parts for the pushbutton version so haven't even thought about the rotary controlled version.

For my part, consider it just an expression of interest in a possible future offering. I know how crazy things have been through the pandemic, and I see what a challenge it is to just to keep the things that you already offer in stock at your store, so no rush, but if at some point down the road you do find the time...

 

[glazer56]

Question for everyone. Building my send set of 8 channels, no problems on the first 8. Ran into some problmes on the second 8 though. on two cards the led's arent lighting on the L/R pushbuttons. None are passing signal.
I had inadvertently dropped some of the transistors into a magnetic dish. Could this be problematic? I'm pretty meticulous with my builds, and before I start tearing things apart i'm wondering if the magnet could affect transistors or diodes? Thanks!

 

[Golgoth]

Question for everyone. Building my send set of 8 channels, no problems on the first 8. Ran into some problmes on the second 8 though. on two cards the led's arent lighting on the L/R pushbuttons. None are passing signal.
I had inadvertently dropped some of the transistors into a magnetic dish. Could this be problematic? I'm pretty meticulous with my builds, and before I start tearing things apart i'm wondering if the magnet could affect transistors or diodes? Thanks!

Have you tried testing said transistors to check if they're okay?

 

[glazer56]

Have you tried testing said transistors to check if they're okay?

Haven't got to that yet. Hoping to exhaust all other options before I start desoldering. I have 8 channels of working cards, so i've been using that to compare the new ones to. the four new cards aren't passing signal, and having problems on the button LED's. when powered up, they won't light when the switch is depressed. I powered one card up without the meter card attached, and they do work however. Obviously, something wrong with the meter card. All the parts look good and correct, so i'm at a loss here. Still not sure why there's no signal though. Possibly the opamp. I was considering pulling a DT05 from a good card and swapping it out, but that's my last resort. Not having a schematic makes it a little tricky to track down problems, Maybe Jeff could chime in with a direction to look? I'm generally super anal with builds, but this one has me stumped, especially since it's the same issue on all four boards. I think it's time for a scotchy scotch.

 

[jsteiger]

I would dbl make sure all transistors made it where they were supposed to go. Easy to swap 3904 with a 3906 then no switching works or meter constant current etc.

Also you can verify if there is signal at the 220µF caps which is after the DTO5 and before the on/off bus switching.

 

[glazer56]

Thought I'd post an update for future builders, in case they have similar issues. Two issues; Main problem is that I tried to clean the PCB's with isopropyl instead of flux cleaner, so It just smeared the flux around causing intermittent connections with the card edge pins. LED issues, no sound ect. Picked up some flux and contact cleaner and solved the issues with the cards. Before this I thought it was a brilliant idea to test one of the cards without screwing it into the front plate (I blame the scotch) shorted something out and smoked the two 10ohm PR resistors on the bottom channel. Once I cleaned the board and replaced the PR's I saw the meters on the bottom channel were pegged. Oscillating opamp i assume. Pulled the opamp and replaced Q4 which was bad. voila. 8 more channels of CAPI goodness. Jeff, ever thought about socketing those opamps? Would make repairs a little less painful. Thanks for the help!

 

[Dr.Weezil]

You can use isopropyl alcohol, but it just has to be 90% or 100% if you can find it. Otherwise, you have to keep applying it to get the flux off.

 

[Brian Roth]

You CANNOT just apply any sort of flux cleaner and then expect the residue to magically go away. You have to blot off the PCB once the solvent is applied and still "wet". Usually, it takes several applications.

Bri

 

[jsteiger]

This stuff works great.

https://gokimco.com/products/microc...-esd-safe-no-clean-flux-remover-10-oz-aerosol

 

[grievousangel]

Well ... the smoke escaped from PR1 on the SumBus2-MTR 'piggyback' PCB!

After verifying +/-16VDC on the front side of the backplane PCB with A-D outputs installed, I plugged in the first bank of input channels. On initial power up of my SumBus32 with only input channels 1-4/9-12 plugged in, PR1 on the SumBus2-MTR PCB failed on all channels except channel 2. After looking over the 4 input modules, they appeared OK except for the PR1 10R CF. Strangely, channel 2 PR1 showed NO evidence of excessive heat. From my understanding that is the design purpose of the PR 10R resistor(s). It would seem the focus should be the meter LEDs and the comparison ICs, but why 3 out of 4?

Jeff, what do you think is likely happening?

The PR1 is in the +16VDC path, PR2 in the -16VDC, correct?

Are the _L rails of the Filter Module for the logic +/-16VDC?

Anyone else had similar issues?

Thanks for the help. Later

 

[grievousangel]

Well ... the smoke escaped from PR1 on the SumBus2-MTR 'piggyback' PCB!

After verifying +/-16VDC on the front side of the backplane PCB with A-D outputs installed, I plugged in the first bank of input channels. On initial power up of my SumBus32 with only input channels 1-4/9-12 plugged in, PR1 on the SumBus2-MTR PCB failed on all channels except channel 2. After looking over the 4 input modules, they appeared OK except for the PR1 10R CF. Strangely, channel 2 PR1 showed NO evidence of excessive heat. From my understanding that is the design purpose of the PR 10R resistor(s). It would seem the focus should be the meter LEDs and the comparison ICs, but why 3 out of 4?

Jeff, what do you think is likely happening?

The PR1 is in the +16VDC path, PR2 in the -16VDC, correct?

Are the _L rails of the Filter Module for the logic +/-16VDC?

Anyone else had similar issues?

Thanks for the help. Later

The channel 'Selected' LEDs are working correctly now as I solved that problem. The VU LEDs are still not working.

Jeff or anyone,

On the SumBus Input Channel (SB-2T) where would be the better location be to test for signal presence on the SB-2T PCB? It would seem I should hunt for the signal on the 4-pin header connections (if +/- 16V is on the 3-pin header? With +4dbu incoming I should measure ~ -2dbu at Output. Unless mistaken, I did measure that ~ value at Output A/L. It would be much easier if a few TP measurements were given. It's 'all good' if it works properly, right! BTW, I remember a rock band named 'All Good' decades back.

Wouldn't my SumBus2-MTR PR1 issue almost have to be local to the MTR PCB? The Comparator IC's are getting warm as well. I see no bad MTR solder joints or similar yet. Still looking. I am going to carefully go over the transistors and the diodes on the MTR PCB now. Cursively they look OK. After that ... replacing the ICs is not an easy endeavor. To draw the amount of current to smoke PR1, it would seem likely to be the drive transistors at fault. Y'all agree?

Suggestions anyone?

 

[JW]

What is better for a monitor output?

1. 2503's extra secondary winding feeding a 10K attenuator? (In addition to the main mix outputs) or
2. Another set of 2503's tapped off of the same ACA booster output (which feed a 10K attenuator?)
3. Another booster circuit (could even be transformerless? feeding a 10K pot, Tapped off the output of the first stage or even second stage)

 

[jsteiger]

What is better for a monitor output?

1. 2503's extra secondary winding feeding a 10K attenuator? (In addition to the main mix outputs) or
2. Another set of 2503's tapped off of the same ACA booster output (which feed a 10K attenuator?)
3. Another booster circuit (could even be transformerless? feeding a 10K pot, Tapped off the output of the first stage or even second stage)

The ACA output transformers are strapped 1:3 so there is no unused winding. I would use an IC -6dB receiver at the final output.