JW

Re: [BUILD]CAPI 2-ACA-Bo~Official Support Thread
« Reply #540 on: November 12, 2020, 01:51:09 PM »
This question concerns the "booster" boards that Jeff also has available. I wasn't sure where to post so thought I would here.

I'm trying to make a 4 channel 312 mic preamp out of one of these boards.

On these boards, there is one CR1 and and one CR2 diode for the main DC power rails supplying all 4 opamps.  And there are 10R resistors in series on the main DC rails locally (close to each 2520)

I can see the other mods I need to make to make it into a 312, but do I need these 10R resistors to isolate each 2520? And is the value (10R) good for a mic preamp?

Just asking because they aren't there on say, a single channel of CAPI VP312.


boji

Re: [BUILD]CAPI 2-ACA-Bo~Official Support Thread
« Reply #541 on: November 12, 2020, 09:25:07 PM »
If you short out your system, you'll be happy a 10 ohm resistor took one for the team instead of your opa.

orangerec

Re: [BUILD]CAPI 2-ACA-Bo~Official Support Thread
« Reply #542 on: December 14, 2020, 10:55:06 AM »
So, I'm trying to revive this 24x2 summing mixer. I'm finally going to finish this project (thanks covid?). Here's my signal flow: out of my Apollo 16>line xfrmr(600ohm out unbalanced)>pan pot(10kpan from CAPI) or LCR switch, 47k ohm buss resistors>CAPI ACA. My question is, do I have to worry about crosstalk between channels with a LCR switch or panner or is the ACA a virtual earth (VE) design and I don't have to worry? Thank you.

https://www.capi-gear.com/catalog/images/gallery/pots/BI/Passive-pan-pot-network.pdf
https://www.capi-gear.com/catalog/images/gallery/PCBs/2-ACA-Bo/2-ACA-Bo-Block-diagram.pdf
https://capi-gear.com/catalog/images/gallery/PCBs/2-ACA-Bo/CAPI-2-ACA-Bo-Rev-B.1-schematic.pdf

boji

Re: [BUILD]CAPI 2-ACA-Bo~Official Support Thread
« Reply #543 on: December 14, 2020, 08:35:01 PM »
Quote
do I have to worry about crosstalk between channels with a LCR switch or panner or is the ACA a virtual earth (VE) design and I don't have to worry?

Yes aca's use virtual earth, but you should always be concerned about crosstalk.   ;)

A solid return reference and PSU is a must, as well proper shielding both in wire runs and overall design.
« Last Edit: December 14, 2020, 09:03:54 PM by boji »

orangerec

Re: [BUILD]CAPI 2-ACA-Bo~Official Support Thread
« Reply #544 on: December 14, 2020, 09:04:47 PM »
Thanks boji! Yes, I'm using the CAPI floor power supply. As well, proper shielding is always good practice. Another question: I'm leaning toward the LCR switch for a simpler design. All i could find is a 3 position 4 pole switch. Am I right in assuming that I could still use it as a single pole, ignoring the others? Also should I go for a shorting or non shorting switch? Here's a link to the switch if you're inclined? Thanks again!

https://www.mouser.com/ProductDetail/Alpha-Taiwan/SR2511F-0403-19R0B-E9-S-W-159?qs=8%252Br4Hz5Xir%2FmSW9A%252BgefJA%3D%3D

boji

Re: [BUILD]CAPI 2-ACA-Bo~Official Support Thread
« Reply #545 on: December 15, 2020, 01:05:04 PM »
Quote
Am I right in assuming that I could still use it as a single pole, ignoring the others?

Yes, but might as well double-up poles. Btw I'd move questions like these off the ACA support thread.


Re: [BUILD]CAPI 2-ACA-Bo~Official Support Thread
« Reply #546 on: January 11, 2021, 07:49:23 AM »
Ok, I just finished standalone summing mixer with capi aca. I have hem simple as can make. Sound is same or even better than my SPL MixDream. Its little bit more open from mid to high. Not much more difference. I have build mine arround 500€ and SPL is 1000€.

Re: [BUILD]CAPI 2-ACA-Bo~Official Support Thread
« Reply #547 on: January 11, 2021, 07:50:42 AM »
Foto 2

Re: [BUILD]CAPI 2-ACA-Bo~Official Support Thread
« Reply #548 on: January 11, 2021, 07:51:18 AM »
Foto 3

Re: [BUILD]CAPI 2-ACA-Bo~Official Support Thread
« Reply #549 on: January 11, 2021, 07:51:57 AM »
Foto 4


Re: [BUILD]CAPI 2-ACA-Bo~Official Support Thread
« Reply #550 on: January 11, 2021, 07:54:07 AM »
foto 6


 

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