4xTHAT2181 VCA board for GSSL etc builds, DBX 202X replacement

[Igor]

I have some leftovers from MixBuzz1 VCA PCB's.

Adding to WM thread... you can have these boards for free included with my other projects or buy.

Schematics and info about some VCA's - here:

http://twin-x.com/groupdiy/displayimage.php?album=416&pos=6

All info I have about 202 VCA's is included into archive.

Please check about using VCA replacement board here:
http://www.groupdiy.com/index.php?topic=41654.0
And here:
http://www.groupdiy.com/index.php?topic=39459.0

 

[tekno808]

Igor,

I ordered MixBuzz1: 2x pcbs, 2x basic kits, 2xMix, 2x sc filters, 2x LED meters and payd with paypal transaction id 1UG54868NW3143524 on January 18 .
Can you send me 4 MixBuzz1 VCA PCB's ?

Thx,

Danny.

 

[Igor]

The kits are sent. Don't have to add VCA boards.

Please check:
http://www.groupdiy.com/index.php?topic=29771.msg360346#msg360346

a pair of these boards are already included with MixBuzz1, as well as many other options.

 

[ptron]

hey great ! i was asking bout this earlier !!
btw
i ordered 6x bypass pcbs earlier this week or last weekend  how would it work to send 4 of these ?? (if shipment hasnt been made yet)
should i pay for 2x 2181 pcb and the other 2 u give from last order??


thanks!!

 

[Igor]

I will check, but 99% the bypass PCB's already were shipped.

 

[ptron]

damn! thats good service!! this is the first time i wished otherwise

 

[ptron]

i got 3 questions hehe
1- if the 5534 can be changed with opa604 and if so if that would make any difference in the sound or performance of the vca?.
2- also was wondering if all the parts inside the vca replacement circuit in the GSSL main board should be removed or not? ..

3- and what part or whats the name of the pins that connect them boards to the gssl? i have no clue

thanks a lot in advance

 

[Ptownkid]

The ones on this pcb would be called "pins" and the ones on the gssl board would be called "sockets". The ones everyone uses are made by a company called Mill-max, check digi-key.com

Cheers

 

[Igor]

1- if the 5534 can be changed with opa604 and if so if that would make any difference in the sound or performance of the vca?.

5534 used to buffer CV, brought down from 6mv/db to 20db/V by resistor divider, to control port of VCA.
OPA604 used at control port of vca will not make sound better, however, 5534 can have some mv DC offset at its out,
depending on batch, and 604 has more DC precision. Let's take medium-bad case.
If 5534 used in left vca has -1.5mv offset and 5534 used at right board has +1.5mv dc offset at output, when input of
control port shorted, this can give difference between channels 0.5db at unity gain.

In other words, to make both VCA boards GR tracking same, use 5534 with same initial dc offset or opa604.

2- also was wondering if all the parts inside the vca replacement circuit in the GSSL main board should be removed or not? ..

I am not a fan of GSSL.
VCA board can be used same way you use here DBX202XT, just without skewing input/output resistors by 1k25.
As well, VCA used in GSSL with gain drop, you have to ask this question to somebody who more familar with gssl than me.

For me it is easier way to build MixBuzz from scratch instead of freakin' with GSSL's weirdness.

3- and what part or whats the name of the pins that connect them boards to the gssl? i have no clue

Take the leftovers after  4002 diodes or another components with fat leads and simply solder.
For Millmax sockets, you probably will need to drill the bigger holes in pcb, etc.

 

[ptron]

thanks a lot for the quick replies! im gonna look for that movie hehe thanks for the tip
ill keep asking around on the main thread if i got a doubt when the boards arrive and time comes. thanks tho for the explanation. and the 4004 tip.. priceless
im enjoying making this gssl weirdness tbh im getting to learn some stuff and lovin it!! (agreed much easier to build mixbuzz and most likely better results haha)

anyways!

 

[Igor]

Yes, for learning purpose, making GSSL compressor is brilliant))))))

 

[ptron]

hehe i love my wirebug

 

[Igor]

Yap, have a fun and enjoy!
For real learning purpose: download the docs folder for this VCA rep board and take a hour to read pdf's)))

 

[ptron]

Heheh was doing that last night actually. Still lot of things are a mistery to me  ;D

 

[Igor]

Little by little)

 

[mac]

Hi Igor,
excuse my ignorance but what is the back story on wanting to use these VCA boards? I just read through some of the posts you have listed - which will provide a few days of reading in terms of the technical side of these VCA's, but i wondered why the attraction to the DBX202XT?

Mac

 

[ptron]

well im not igor but would like to say what i think and why i want them, with 4 paralell vca`s first and not so importantly.. the noisefloor will drop for about 6db`s (so i heard).. secondly .. dynamics for the vca will be much greater so u wont have as much grain or distortion when using high ratio.
again its what i read and im not entirely sure about it..
boards are on their way and ill post my impressions when i got them fitted

 

[ptron]

hello igor im happy to hear you are getting on with things and making a website is right on congrats!!

im wondering about a couple of things since boards should be about to arrive im getting goosebumps!

about the bom tho... there are a couple of unspecific things id like to ask you about


*FROM BOM*

CERAMIC CAPACITOR PITCH 2.5MM/POWER SUPPLY BYPASS
4  47N...220UF  CBP20, CBP21, CBP22, CBP23

1 22...47 PF CERAMIC CAP PITCH 5MM DON'T USE WITH OPA604 AT PLACE OF IC9

CAPACITOR-POLY', 5MM PITCH, 50-63V
1   0.1UF  C5/2.5          C44

***

1-first those 4 ceramics for CBP2X`s.... how should i pick the value ? is there a difference in the performance?

2- about the poly there.. its for C44 right? ("C5/2.5".... im confused with those letters i am thinking they dont go anywhere in the board..)

3- what kind of ic sockets would fit there? the space looks very reduced and now trying my best cant fit 4 in hehe
thanks a lot!

 

[ptron]

well the boards got here yesterday!! great work they look tidy! thanks a lot igor

just a question... in the original THAT schematic for paralell it has rMagic and Symmetry trimmers... i think the one in the GSSL (distortion trim) is one of them (symmetry)...  but is it not necesary to have the other one too ? just wondering before i order all the parts

thanks again

 

[ptron]

bump sorry still wondering bout these things