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

[jsteiger]

What happened to these, Jeff?

Not seeing them in the store anymore.

Am I blind or just dumb?

Hey Skylar,

You are neither blind nor dumb my friend!  8)

I ran out quick at the end. I have more on order. I should have them in about 9 or 10 days. I will update the item so it shows the date expected. I forgot to do that so thanks for the reminder!

Cheers, Jeff

 

[jsteiger]

Inverter is found at http://classicapi.com/catalog/product_info.php?cPath=22_46&products_id=55
ACA is not found

Thanks kazper. 

ACA is now visible again with date expected at http://classicapi.com/catalog/product_info.php?cPath=22_46&products_id=81

Best, Jeff

 

[Skylar]

Cool!


I just bought a 42-channel Wheatstone SP-5a broadcast console.

I was thinking about replacing the master bus with a 2-ACA-Bo or a Neve 1272 line amp.
Maybe I'll try both...hmmmm.

 

[plumsolly]

Hey Jeff, I was thinking about using the my 4-aca card for buss summing. It would be the output of each aca to an unbalanced insert point normalled to a fader and then sent to the 2-mix. Or something along those lines. Does that sound reasonable to you? - Thanks and Best, Ben

 

[3nity]

Hey Skylar i really dig that mixer...
I'm looking for a decent mixer 32 channels who knows!!
It looks great!

 

[jsteiger]

Hey Jeff, I was thinking about using the my 4-aca card for buss summing. It would be the output of each aca to an unbalanced insert point normalled to a fader and then sent to the 2-mix. Or something along those lines. Does that sound reasonable to you? - Thanks and Best, Ben

Hey Ben,

One thing to keep in mind is that the Inv-ACA is an inverting only ACA. To interface with the outside world, you will have to invert the phase again. Easiest way is with a transformer. If you look at the 2-ACA-Bo skiz, you will see that I am inverting the phase with the 2623 style trafo. Basically, if you add a 2623-x after each of the separated outputs of a JLS-Inv-ACA card (not bussed together and no 47K buss R's), you have the first half or ACA only part of the 2-ACA-Bo card. I hope that makes sense.

Yes, an insert point normalled to a fader, then thru a 47K buss R is API style all the way.  ;D

And yes Skylar, I agree with 3nity. Nice looking desk.  8) Your new bolster really makes it! Is it fully functional or a work in progress? What kind of fun would fully functional be?!? 

Cheers, Jeff

 

[Skylar]

And yes Skylar, I agree with 3nity. Nice looking desk.  8) Your new bolster really makes it! Is it fully functional or a work in progress? What kind of fun would fully functional be?!? 

Thank you 3nity & Jeff!


*Unfortunately*, this desk is fully functional!
Inputs are all line-level, EQ actually sounds really nice, has a cool control room section, and is pretty basic otherwise.

All the summing is unbalanced, so it seems more appropriate to drop in a 2-ACA-Bo rather than a balanced input 1272 Neve-y thing.
Besides, the power rails are +/- 17V, and I don't feel like building a separate 24V supply just for a master bus summing amp.

This project is down on my list right now, though, behind two or three other things.

 

[plumsolly]

In this block diagram of the bus section of the sixteen-o-eight it looks like they have the bus fader buffered before it goes into the stereo bus. So I guess I would want to use 2-aca cards for each pair of buses, stuff everything except the 2503's and run the outputs through 47k resistors to the stereo bus. I guess this way maybe I could put a pan pot between the output of the bus buffer amps and the stereo bus - that way my mono buses wouldn't have to be left, right, or center only...
-Ben

 

[THE BAD DOGS]

Hello,

I want to use your 2 aca booster in the master section of my soundcraft 600. Where can i connect the module?

Schematic : http://img29.imageshack.us/i/soundcraft600mastersect.pdf/

Thanx,
Jean-Christophe

 

[Rob Flinn]

I have nearly finished my ACA board & am looking to make a box to mix direct from my digi 002 rack. I thought before I started to hook this up I would just run it past you guys, to see if anyone any ideas to improve my idea, or tell me why it's not good.

I was thinking of trying to make the unit so I had 8 mono feeds  for vocals, guitars etc & 4 stereo feeds for drums etc  Is this a reasonable configuration or would it be better as 3 st & 10 mono  etc  ???

I also wanted to make all the inputs go through a normalised B gauge patchbay so that I could insert real compressors & eq's.
One of the things in my head is I'm wondering if I am inserting different compressors between the 002 rack & the ACA with the differing output impedances from the compressors will screw the gain structure for the ACA when comboning with mix resistors ?

 

[Rob Flinn]

Bumping my previous post

Also I'm wanting to add a 2 buss insert point.  I'm think that this might want to go after the ACA but before the fader.  Would it be pertinant to add a balanced insert buffer before the fader since I don't have any unbalnced gear I would be inserting at this point ?

 

[plumsolly]

Would it be pertinant to add a balanced insert buffer before the fader since I don't have any unbalnced gear I would be inserting at this point ?

You are talking about adding a debalancing circuit before the fader? I'm not sure this is necessary - In the original design, with nothing inserted, it will still be balanced ACA output > unbalanced fader. So i assume it is ok to drive the fader with balanced gear, but perhaps the design is from a time when things were either unbalanced or transformer-balanced - I still don't understand the difference in implementation between 'electronically balanced' gear and transformer-balanced. Not sure if that makes this any less confusing. Best, Ben

 

[Rob Flinn]

That seems to make sense, thanks Plumsolly

 

[jsteiger]

Ben is right. With nothing inserted, it will be a balanced ACA output feeding an unbalanced fader input. The fader wiring will unbalance whatever comp or eq you have inserted by connecting the low side of the balanced signal to ground. Probably won't be an issue for most gear. Like Ben mentioned, when my desk was manufactured, most gear had transformer balanced outputs.

On a similar topic, this is why the API eq modules have an unbalanced input and a transformer balanced output. They were designed as part of the input channel "strip", if you will. The unbalanced eq input is driven by a 2520 into a 2623-1 transformer(on the input channel). The eq output drives the channel fader. Balanced output to an unbalanced fader, same concept as the insert point on the ACA.

Rob, as far as the inputs you mentioned, that will be a console sort of structure. Your mono inputs will have to be split into (2) 47K buss resistors. You will have to find the proper value resistor to put just before the buss R's to get a 3db, 4.5db drop or whatever you want for a mono signal. You will be unbalancing the outputs of whatever gear you are combining with the ACA. Shouldn't be an issue at all unless you are running 100' cables between everything.

Cheers, Jeff

 

[ask]

There could be an issue with typical electronically balanced outputs (which most modern gear has), since you are, in essence, shorting an amplifier (low/cold/neg./pin 3) to ground, it COULD misbehave, which MIGHT affect the high/hot/pos./pin 2 signal - you could lose headroom and/or get increased distortion.

The quick fix is to leave the negative (pin 3) open/disconnected, just make cables that don't ground it!

*NOTE: a RARE variety of electronically balanced outputs react like a transformer, which needs to be shorted to ground in order to get an unbalanced signal from it. *

Ben is right. With nothing inserted, it will be a balanced ACA output feeding an unbalanced fader input. The fader wiring will unbalance whatever comp or eq you have inserted by connecting the low side of the balanced signal to ground. Probably won't be an issue for most gear. Like Ben mentioned, when my desk was manufactured, most gear had transformer balanced outputs.

 

[jsteiger]

I use to have a few "special" patchbay cables that had the low pin floating on one designated end for these situations.

 

[Rob Flinn]

Thanks for this info guys, will get onto it tomorrow, & report.

 

[Rob Flinn]

I was just wondering whether it is better to terminate the unused cold signal of an electronically balanced output to ground rather than leave it floating, when running into an unbalanced input ??

 

[ask]

Normally no, as I've tried to explain. You wouldn't ground an unused side of a power amp if you only used one speaker, would you?

(What you want to ground is an unconnected INPUT, so it doesn't act as an antennae, and pick up stray noise)

I was just wondering whether it is better to terminate the unused cold signal of an electronically balanced output to ground rather than leave it floating, when running into an unbalanced input ??

 

[Rob Flinn]

Normally no, as I've tried to explain. You wouldn't ground an unused side of a power amp if you only used one speaker, would you?

(What you want to ground is an unconnected INPUT, so it doesn't act as an antennae, and pick up stray noise)

Sorry, what I meant to say was terminate through a resistor, & no I wouldn't terminate the unused side of a power amp !!