[BUILD]CAPI 2-ACA-Bo~Official Support Thread

[Benny]

I'm doing the first listening test right now. 8 tracks of drums line out straight into 2-ACA-Bo. It worked from first power-up and sounds GREAT. Time to order more D-Sub connectors!!!

Benjamin

 

[brennyb]

this is all exciting,
2 Doa's built and 2 to go,
glad to see people enjoying, and great support here...
keep it up,

Brendan 

 

[0dbfs]

Question:

Can I fit 2 ACA-OBO's into 1RU for four bus masters sort of like a 7800 form factor?

Thx,
J

 

[jsteiger]

Question:

Can I fit 2 ACA-OBO's into 1RU for four bus masters sort of like a 7800 form factor?

Thx,
J

The PC mount 2623-4's would be very close after some standoffs are used under the board. The vertical 2503's will never make it. I would suggest just mounting the iron off the board and flat. I would do this will all 4 transformers and use 2623-1's instead of 2623-4's. Then...no problem with everything fitting.

Best, Jeff

 

[rrs]

Hi Jeff

I am wanting to build a 14:2 channel mixer in which all channels can pan either Hard Left, Center or Hard Right.

Can I use these boards to do this and how would it be done.

 

[JBVries]

So, a DIY, all modular, vintage API style mixer. This is so do-able, and ultimately my goal.

I'm just starting to thumb through this thread, but I like the sound of that  Sooo many avenues for complete signal path customization.

 

[haima]

Hi Jeff

I am wanting to build a 14:2 channel mixer in which all channels can pan either Hard Left, Center or Hard Right.

Can I use these boards to do this and how would it be done.

Hey David - balanced or unbalanced?

 

[bluesbaz]

I would like to use the aca as a stand alone summing system. I was thinking of summing 8 balanced channels at a time and hitting a transformer before going into the summing card and then to the aca stage. Is there anything I should be concerned with when doing this? Or should I just unbalance the inputs?
I have 8 1731 and 8 2520 waiting to test in this circuit..... Should be fun!
Thanks again!
-s

 

[bluesbaz]

Nothing..... Really?
-s

 

[jsteiger]

Well, you could use Don's "Stereotype" boards and have a discrete front end to the summing. That may be more fun than a transformer. He did them in 8 channel units IIRC. It really depends on the device you are getting the balanced signals from as far as just unbalancing them. A simple unbalancing would be the most cost effective way to start. Either the low side to ground or float. If you have problems or are not happy, then maybe you could look at an alternative like Don's boards or maybe transformers.

 

[herrmann]

Hi
I'm very happy with my 13/2 little mixer, I want to upgrade a bit, thinking of adding some busses, maybe aux. Can I do it with your 4 ACA board ? Adding on each a 2623 phase reversed=>balanced insert point=>pot=>47k=>2 ACA Bo board. One board for 4 independent busses.

 

[jsteiger]

Yes, that should work.

 

[funkmuffin]

Hi Jeff -- I'm building my 2-aca-bo, and need to get the 2623-4's oriented correctly.  Is the blue dot on the transformer pin #1?  I'm assuming so, but it's easier to ask then to de-solder. 

Thanks!

 

[jsteiger]

Hi Jeff -- I'm building my 2-aca-bo, and need to get the 2623-4's oriented correctly.  Is the blue dot on the transformer pin #1?  I'm assuming so, but it's easier to ask then to de-solder. 

Thanks!

Correct you are funkmuffin. Blue dot = pin #1.

Desoldering can be mighty enjoyable with the right tools  ;D  Don't underestimate it!

 

[haima]

Desoldering can be mighty enjoyable with the right tools  ;D  Don't underestimate it!

+1 

 

[Marcocet]

Okay, I'm finally getting started on my headphone cue mixer project. The plan is essentially to build little 10 channel API mixers (8 mono 1 stereo) with built in headphone amps. I've really only got one question but I figured I should run the whole thing by some brains to see if I'm missing anything else.

The plan is to use one of Don's Stereotype boards per mixer. That should give me 8 mono inputs. Instead of the multi point pan I'm just going to use a LCR switch with 5k resistors. Then I'm planning to use an ACA/booster board. The boosters I'm going to use as input amps for the L and R stereo, matching the components to the stereotype boards and bypassing the transformer (also I think I need to reverse the input leads?). The aca will be the left and right summing amps (no master fader, I'm just planning to use the volume on the headphone amp as a master). These are gonna go directly to a Purple CANS headphone amp with no input transformers.

Anybody see any offhand flaws in this plan before I build a prototype? Also does anybody have a good source for 1k faders?

Thanks

 

[rhythminmind]

• So I'm wanting to do a little experiment, but need some input. I would like to sum the output of a fulcrom (16 channel balanced resister network) into a 2-ACA-Bo. The resistor network has a 10k balanced input. Uses 5k on each +/-  ...
  
  After reading thru the thread, I have a few questions.
  • Is the output of the ACA line level? It seems I can just take the ACA transformer output into an A/D, or do I need the booster?
  • The input to the ACA is unbalanced correct? I would rather keep the the summing network balanced. Could I just use a pair of 10k:10k line transformers (JT-11P-1) before the ACA input?
  • Would I change the feedback R to 10k with a 400pf cap? Anything else needed to change?
  • Also the fulcrom is originally intended to be used with a mic pre for makeup gain & has a shunt to create a 150ohm output, The ACA being an inverting summing amplifier I don't think the shunt will  have any effect..?
  
  So all in all my idea is 10k network > 10k 1:1 transformer >  ACA > bus comp/A/D. Have I missed anything?

 

[jsteiger]

Is the output of the ACA line level?

No, it is -2dB. You could adjust if this is the only stage you are gonna use.

It seems I can just take the ACA transformer output into an A/D, or do I need the booster?

Yes you can do this. Besides more DOA and x-fo goodness in the path, they are there to buffer the pgm mix fader and insert point. If you don't use these things, you could skip the booster section.

For the rest, you will have to experiment IMO. I have not used one in this way so can't say for certain what needs to be done.

Cheers, Jeff

 

[piano]

I am building a summing box.

I have a SUMTHING and the 2-ACA with DOA's coming. (I will order the extras which go with this.)

Besides the usual DB25, XLR connections is there anything I am missing?

 

[3nity]

Hi people.
I never been interested in summing stuff but since im working on my console.
do you guys think an Einstein would work well with the ACA??

Im pretty new about summing...

Thanks.