mokkinger

Balanced I/O for Pico SE Compressor
« on: February 12, 2019, 02:48:33 PM »
Hi Guys,

I finally  finished building my Stereo Pico Compressor, and would now love to include it into my setup... which is all balanced XLR, and I dont want to use it unbalanced as it was designed. Now I thought about a That 1646 circuit similar to the ones from
https://www.diyrecordingequipment.com/collections/all-products/products/balanced-output
which are out of stock and probably discontinued...? 

any idea who makes similar boards, or what other neutral, good sounding balanced I / O solution are there that I could use? 

thanks for hints,
Mark
still learning to fly...


JohnRoberts

Re: Balanced I/O for Pico SE Compressor
« Reply #1 on: February 12, 2019, 03:28:43 PM »
Is it giving you a problem?

JR
John Roberts
http://circularscience.com
Tune it, or don't play it...

mokkinger

Re: Balanced I/O for Pico SE Compressor
« Reply #2 on: February 12, 2019, 03:39:53 PM »
no, the comp works fine so far.

I am just looking for an appropriate Balanced Input and Output solution... would the That 1646  be the right one for the pico?

thx,
mark
still learning to fly...

JohnRoberts

Re: Balanced I/O for Pico SE Compressor
« Reply #3 on: February 12, 2019, 04:39:59 PM »
The THAT corp chip sets are well respected, while I have never used one. Others here surely have. 

Unless you anticipate difficult interface situations you may be addressing a problem that isn't there.

JR
John Roberts
http://circularscience.com
Tune it, or don't play it...

mokkinger

Re: Balanced I/O for Pico SE Compressor
« Reply #4 on: February 12, 2019, 05:39:49 PM »
so you would recommend using it unbalanced?

it kind of irritates me, that I run audio from a desk to lets say different comps & EQs, all balanced, then go into the pico unbalanced and from there again into a balanced tape machine... wont I loose gain by just discarding the ring signal?

Mark
still learning to fly...

EmRR

Re: Balanced I/O for Pico SE Compressor
« Reply #5 on: February 12, 2019, 06:29:56 PM »
Did you build stereo from 2 original mono modules?  The stereo board is balanced I/O.    Balanced is 1246/1646 implementation. 
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde

buildafriend

Re: Balanced I/O for Pico SE Compressor
« Reply #6 on: February 12, 2019, 09:21:03 PM »
it's always nice to have balanced ins and outs. generally the point of balanced ins and outs are to help maintain signal integrity while sending signals on long runs or near noisey areas like behind equipment, close to power cables, etc. balanced is the better option. that said, it's not necessary ( for your time on task or wallet ) if you aren't up against long signal lines or areas with EMR. it might be just fine the way it is

if you do want to do a balanced input and output there are more options than THAT chips, but THAT chips are nice :)
« Last Edit: February 12, 2019, 09:26:30 PM by buildafriend »

mokkinger

Re: Balanced I/O for Pico SE Compressor
« Reply #7 on: February 13, 2019, 03:53:59 AM »
@Doug yes it's da dual mono built. Have the populated boards since years, now tested them and found it sounds just great.

I see the point of time and budget, but as I take a lot of effort building these things I want to take all things into account.
My stuff passes quite some way through multicore, and I want to make sure not bringing noise or ripple into audio as it's the final path before the tape...

Arent there any  pcbs around for this?
still learning to fly...

Re: Balanced I/O for Pico SE Compressor
« Reply #8 on: February 13, 2019, 10:20:08 AM »
What exactly are you looking for? A pair of THAT1246's for in and another pair of THAT1646's for out?

You could always pick up some 10k:10k transformers for in and 600:600 for out.

JohnRoberts

Re: Balanced I/O for Pico SE Compressor
« Reply #9 on: February 13, 2019, 10:29:53 AM »
@Doug yes it's da dual mono built. Have the populated boards since years, now tested them and found it sounds just great.

I see the point of time and budget, but as I take a lot of effort building these things I want to take all things into account.
My stuff passes quite some way through multicore, and I want to make sure not bringing noise or ripple into audio as it's the final path before the tape...

Arent there any  pcbs around for this?
There are PCBs around the WWW for THAT I/O chips, I don't think THAT sells them.

JR
John Roberts
http://circularscience.com
Tune it, or don't play it...


Re: Balanced I/O for Pico SE Compressor
« Reply #10 on: February 13, 2019, 11:05:33 AM »
What exactly are you looking for? A pair of THAT1246's for in and another pair of THAT1646's for out?

You could always pick up some 10k:10k transformers for in and 600:600 for out.

Drew this up right quick.  Someone should probably check it. Left the inputs DC coupled per the recommendation of the THAT datasheet.

You can order the PCBs straight from this link, or edit, or whatever you like. $2 for 10 plus shipping.
https://easyeda.com/editor#id=|38782cd904434ce0969493d52726cb47|e1e2f49eaea14f79bec80314b0e21d56
« Last Edit: February 13, 2019, 11:20:19 AM by dogears »

mokkinger

Re: Balanced I/O for Pico SE Compressor
« Reply #11 on: February 13, 2019, 03:17:18 PM »
Oh, thanks a lot! very cool!!

I would order it right away - from my understanding this looks all fine - but I am def. no expert ;)
anyone else saw this?

thanks guys, I really appreciate all your help!!
Mark
still learning to fly...

EmRR

Re: Balanced I/O for Pico SE Compressor
« Reply #12 on: February 13, 2019, 03:19:44 PM »
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde

buildafriend

Re: Balanced I/O for Pico SE Compressor
« Reply #13 on: February 13, 2019, 03:36:26 PM »
Maybe input balance with the above and output  balance with a line balancing tranformer?

mokkinger

Re: Balanced I/O for Pico SE Compressor
« Reply #14 on: February 13, 2019, 03:38:45 PM »
You could always pick up some 10k:10k transformers for in and 600:600 for out.

I think for the Pico the That-solution you just drew is just fine! Have already quite some transformer-based comps...
still learning to fly...

dmp

Re: Balanced I/O for Pico SE Compressor
« Reply #15 on: February 13, 2019, 03:55:32 PM »
Drew this up right quick.  Someone should probably check it. Left the inputs DC coupled per the recommendation of the THAT datasheet.
Nicely done - that is exactly what is in the PICO SEII for input / output.
You could add a bypass with relays to these PCBs while you are at it. 
The XLR connectors should have pin1 ground with signal on p2 & p3. Your numbering is different which is potentially confusing.

Quote
I think for the Pico the That-solution you just drew is just fine! Have already quite some transformer-based comps...
I agree

EmRR

Re: Balanced I/O for Pico SE Compressor
« Reply #16 on: February 13, 2019, 04:27:44 PM »
Looks good.

You might want to add a diode bridge on the output for protection against phantom power. 

Nice to have the power filtering and diodes there for some applications, but could be left out/jumpered for others. 
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde

mokkinger

Re: Balanced I/O for Pico SE Compressor
« Reply #17 on: February 13, 2019, 07:03:18 PM »
I am about to find out how to change simple things like the pins of the headers...  :)
the pico has already a bypass switch, so I guess that's not really needed.
The diode to avoid phantom power damage wouöd be good though... Hmmm
still learning to fly...

Re: Balanced I/O for Pico SE Compressor
« Reply #18 on: February 13, 2019, 08:43:15 PM »
I can add protection diodes and change the pin connections. On my own stuff I just always use pin 1/2/3 as high/low/ground without regard for whether it’s coming from TRS, XLR or whatever.

Re: Balanced I/O for Pico SE Compressor
« Reply #19 on: February 13, 2019, 09:35:45 PM »
Here you go. It's a bit uglier (protection scheme has Vee and Vcc all over the place...) and I didn't really have time to give it an elegant routing, but it should work just fine.

The datasheet says it can handle preamps with caps up to 33 without the diodes with the internal protection on the IC, which is why I left it off initially. If you want the smaller / cleaner PCB or if you like living on the edge, just use the PCB file "no protection".

I left the connection headers pins 1-2-3 as high-low-shield. The shield shouldn't be confused with chassis ground as it is tied into the same ground as the ICs. That should be used if you're using a shielded cable, floated at one end. If you're not using a shielded cable, just use the two pins for high and low.

https://easyeda.com/editor#id=|38782cd904434ce0969493d52726cb47|e1e2f49eaea14f79bec80314b0e21d56

« Last Edit: February 13, 2019, 09:39:29 PM by dogears »


 

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