MS, Pultec, 1/2-BA283 boards support thread!

[izzi]

Thanks for the quick response, I feel a bit silly about the power switch now, however it is all wired up now and I will be testing it shortly, had a couple of glitches, I wired up one of the gain switches wrong and it threw me for a while but it's all ok now, just waiting for my chicken head switches and I'll post some pics and maybe a sound clip.

I have one more question though, can anybody tell me what the adjustment pots are for on the left and right boards? And how do I test etc? Many thanks guys.

izzi

 

[izzi]

Anyone??? :

 

[izzi]

Here's some pictures of my nevtec http://i1133.photobucket.com/albums/m591/littleizzi/igors%20eqp1a%20stereo%20ms/IMAG1128.jpg
I love this unit and so gave it some colourful knobs to go with the sound. The picture quality is not the best but they were taken from my phone.  I do have one question to anyone who has built one of these units, what am I adjusting when I adjust the variable resistors on the left and right pcbs? What should I measure when adjusting?
Many thanks guys
hope you like my build pics
izzi

 

[Igor]

Nice knobs; the knobs themselves does not sound; show us inside of unit!

"Variable resistors": set bias of output half of BA-283, I guess
A lot of info on this subj is posted on infernet.
In general, with 600 Ohm load, the clipping @ 1khz should be symmetric.

 

[izzi]

Hi, I am also getting a lot of noise from the r/s channel when in m/s mode, and also the low freq boost on this channel is either full on or off, no variant control 
I did not notice this when i first tested it.  Any ideas?
Also Igor, I'm maybe not as electronically advanced as most on this forum, so I don't quite know what you meant on your previous post?  Can you or someone on here translate how to adjust the BA283's and exactly where and what I'm measuring for?  :-[
I will post some more pics once this is all sorted 

 

[Igor]

Noise issue: check the power transformer orientation, if the noise is 50/60Hz related stuff.
Try to feed from lab power supply +24V and you definitely know if the power trafo is the source of noise.
If yes, just try to rotate it.
For BA283 BIAS adjust: don't be so lazy, it was explained 100500 times and way better than I can do. Just search this forum
In general, about 80-100ma through the out transformer's primary depending on load. Should be symmetric clipping into 600 Ohm load at output trafo's secondary.
Pics - welcome!

 

[craigmorris74]

I noticed that CZ (10n cap) of the output transformer zobel isn't fitted on the pictures of Igor's boards.  Any reason why?
thanks
craig

 

[bastrika]

Zobel network is on MS PCB

 

[craigmorris74]

Thanks for the reply bastrika.  I'm not using the M/S board, so I need to add it on the 283 board.

 

[jandoste]

Hey Igor,
I am searching those knobs but can't find them where did you get them? do you have any link?
Thanks
http://i251.photobucket.com/albums/gg291/diy33609/PULTEC_MS/P1050865.jpg

 

[noulou]

Hey Igor,
I am searching those knobs but can't find them where did you get them? do you have any link?
Thanks
http://i251.photobucket.com/albums/gg291/diy33609/PULTEC_MS/P1050865.jpg

http://www.musikding.de/product_info.php/info/p1162_Fouredged-knob.html

 

[jandoste]

Hey Igor,
I am searching those knobs but can't find them where did you get them? do you have any link?
Thanks
http://i251.photobucket.com/albums/gg291/diy33609/PULTEC_MS/P1050865.jpg

http://www.musikding.de/product_info.php/info/p1162_Fouredged-knob.html

Thanks Noulou!
Cheers

 

[jandoste]

and finally the carnhill vtb9046 has to be wired in normal to remain unity gain... so that must be all my questions answered...
Kasper Nyhus

Hey Kasper,
Do you have any picture or you can add any info about how did you wire carnhill vtb9046?
Thanks

 

[jandoste]

Hey Igor,
I am bumping on FB but maybe you are not online... or there won't be any support for this project?
Thanks

 

[jandoste]

Hey Igor,
I am bumping on FB but maybe you are not online... or there won't be any support for this project?
Thanks

bump!

 

[jandoste]

Hey Guys,
I don't see any "DOT" on the Inductor...do you have any idea or datashet?
Thanks for any advice...
Cheers

 

[MatthisD]

Try measuring ohms between 'com' and the '312mH' pins and then flipping around to measure the 39mH to 78mH. The higher ohms reading should indicate com and 312mH pins

 

[jandoste]

Thanks MatthisD,
I have already soldered it and I will check it...
for soldering the make up resistors 

   

I am not sure that which one is right?  I soldered them like "across s2" R10= 19R 37DB: 75R
but I think that I don't have 37db... it's low
edit: picture was wrong!
Thanks

 

[craigmorris74]

I'm using the BA283 in a case by itself for my Pultec filters in another case.

On the BA283 boards, on the power connection, pins 2 and 3 are marked -24.  Do I have to connect them both to something or just pin 2 to -24.  They both look like they're going to the ground plane.  If it matters, I'm just using the BA283 without the M/S board.

Also, if I'm not using the M/S board, and there is an unbalanced input coming from a TS connector from my Pultec filters, I wanted to double check-where do I wire this to the BA283 board?

Craig

 

[jandoste]

Igor,
Need some more support! please...