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jensenmann

Re: D-AOC PCBs - the building and help Thread
« Reply #1260 on: November 01, 2014, 03:21:10 PM »
Hello!

Musikding in Germany does not sell the toroidal power transformer anymore. I've tried to find an european alternative, without luck. Any suggestions?

I have all my custom trannies done from this company: http://www.mueller-rondo.com/
I can highly recommend them. No freakbusiness but german precision engineering!
Jens
Quote from: PRR
>The tubes of course don't care what frequency they distort


Miska

Re: D-AOC PCBs - the building and help Thread
« Reply #1261 on: November 01, 2014, 06:31:22 PM »
Banzai carries some of these, and is in Germany too

Which transformer do you mean? I checked through Banzais trannies twice and couldn't find anything even close to the specs for D-AOC.

petermontg

Re: D-AOC PCBs - the building and help Thread
« Reply #1262 on: November 02, 2014, 07:48:45 AM »
Hello!

Musikding in Germany does not sell the toroidal power transformer anymore. I've tried to find an european alternative, without luck. Any suggestions?

I have all my custom trannies done from this company: http://www.mueller-rondo.com/
I can highly recommend them. No freakbusiness but german precision engineering!

Did it set you back much?
Peter Montgomery
+353(0)831918347
info(at)chrmastering.eu

jensenmann

Re: D-AOC PCBs - the building and help Thread
« Reply #1263 on: November 06, 2014, 11:09:58 AM »
no, 50VA trannies are app 40€ + shipping
Jens
Quote from: PRR
>The tubes of course don't care what frequency they distort

MicDaddy

Re: D-AOC PCBs - the building and help Thread
« Reply #1264 on: November 06, 2014, 02:07:55 PM »
For those who will build (have built) D-AOC sans transformers:

On the input, is a cap necessary to prevent possible unwanted DC bias problems at the grid?  If so 1uF puts the pole at ~10Hz if I use 15k as R.  Is there some other input relationship math needed here?

How about for the output, I haven't tried any math to figure the OP impedance but assuming it's 10k, will it be unhappy driving anything less if I take output straight off the 10uF cap?  How about some buffer with op-amps, anyone tried this? 

Silvas

Re: D-AOC PCBs - the building and help Thread
« Reply #1265 on: January 16, 2015, 08:39:16 AM »
Hello,

I've just replaced the edcors on my DAOC : LL1540 (from Sahib) on the inputs and XS1100 (directly from Edcor) on the outputs.  They sound fantastic. Great combo and far superior to the original edcors.  No need for zobels, etc....I ran my DAOC transformerless input for years but the specified edcor outputs still ringed a bit on their high frequency limit.

I also replaced all audio tubes with 6N1P. After playing with many of them, i've found a combo of 6N1P which gave me around 0.1% THD at +20dBu with no compression. I guess because of better match between triodes ?

The sidechain tubes were left as-is (12au7).

I measured individual vactrol GR amount on circuit. Three of them are almost the same, one of them off by almost a dB. I guess i'm getting a couple more vactrols to get a more accurate match.  I tried to compensate using series resistors on the led side of the vactrol but it seems to affect the lowpass corner frequency formed by C104 and the LED, so compression accuracy was screwed a bit on bass-heavy material.

I replaced r126 (33k and "TBD" on LA2A schemo) with 50K trimpot on board to adjust needle precision so i can get accurate readings on both channels at up to 5-6dB GR. I also moved zero adjust trimmers to front.

Now, i wonder if the HT PSU can be further cleaned.  I usually get a significant ripple reduction on the TL783 by bypassing the adjust pin to ground with a 22u/450v cap, but i didn't tested this yet on this particular PSU.

Hope this help. I've always loved this compressor.


druu

Re: D-AOC PCBs - the building and help Thread
« Reply #1266 on: January 16, 2015, 07:28:37 PM »
Is there a source for matched vactrols? I've also found the 500r trimmer on the vactrol leg isn't super accurate.


 

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