D-AOC PCBs - the building and help Thread

[mischa]

Thanks again, MM! The unit finally works!

However it was not the R1 or the voltage, but my stupidity: i didn't realize that the tl783 was grounded, so i had to solder off the heatsink...  :-\

Now it compresses and i can drill holes 


cool forum

 

[[silent:arts]]

cool this is sorted out.

I don't ground heatsinks anymore, but reading some threads I think I should do again
why?
at least with the high voltages you should ALWAYS mount the voltage regulator ISOLATED.
you want to be able to touch it for checking heat etc ...

 

[mischa]

so the unit is finished, but the left channel distorts in the bass, when in compression mode.

also, can someone tell me what the H+ is supposed to do? the one located between the two ground pins left of the psu sections.

otherwise the unit works fine, except for some excess hum on the right.

sounds great, and thanks again for the project!

also a nice christmas present for myself


[edit]

I switched the tubes, but that didn't help to remove distortion. could it be the vactrols? all other values are the same in the two channels.

 

[rob_gould]

also, can someone tell me what the H+ is supposed to do? the one located between the two ground pins left of the psu sections.
[edit]

I'm not at home so can't check mine but I presume this is the positive heater supply for the tubes?

Could be wrong though...

 

[Silvas]

I´m quite close on finishing my D-AOC. Speaking of the heaters reg, i think using the LM350 (on TO3 package) is a good idea. I´m using a LM350T mounted offboard on a quite big heatsink and i´m having thermal shutdown after 15 minutes. Probably, i got a fake 350, don´t know. Maybe i should get a 338K (which maybe is a fake rebranded 350 !!!)

Is there any chance of tube damage with the tubes working at full plate voltage if the heater supply dies after a while ?

I still have to wire the baby, but all voltages are quite fine. I have 247 v after the big resistors (had to change the 47r for a 20r).

 

[mischa]

so the unit is finished, but the left channel distorts in the bass, when in compression mode.

also, can someone tell me what the H+ is supposed to do? the one located between the two ground pins left of the psu sections.

otherwise the unit works fine, except for some excess hum on the right.

sounds great, and thanks again for the project!

also a nice christmas present for myself Smiley


[edit]

I switched the tubes, but that didn't help to remove distortion. could it be the vactrols? all other values are the same in the two channels.

Little help please...

So i soldered out vactrols (kubi version - 2 on each channel), and now only the right channel compresses. the left one does not with one vactrol, only with two.

how can that be?! i switched vactrols again and again - same problem.

compression is more equal with only one vactrol on the right and two on the left, than with two on each side.

also, when i compress on the right side, the neon lamp gets dimmer... but not on the left (of course with 2 vactrols, in compression).

 

[MartyMart]

Mischa, did you "reverse" one set of vactrols ?
So one set with "printed side up" and one on top with printed side down ??

MM.

 

[seavote]

Little help please...
So i soldered out vactrols (kubi version - 2 on each channel), and now only the right channel compresses. the left one does not with one vactrol, only with two.
how can that be?!

the remaining vactrol on the left side is faulty ?? when you wrote that you switched the vactrols again and again its not clear if you were soldering in and out the same vactrols in the same spots or not.
if one of the two vactrols is good on the left side i believe the unit will compress.    just not in  full wave mode (ala Kubi mod)


"compression is more equal with only one vactrol on the right and two on the left, than with two on each side."
if im right this would be expected as both sides are compressing only 1/2 of the audio signal.
if you've thought of this and tested to isolate which vactrol is bad on the left side.my apologies. i was uncertain what you meant by switched the vactrols out. good luck. you'll like this unit when it is running with no bugs

 

[mischa]

MM, yes, i had them like kubi wanted, one facing up and one down. Also, Musikding delivered two pairs with different numbers: one pair has 511 written on it and the other one 636. must be the batch number.

sorry for the unclarity. what i meant was i switched the remaining vactrol for another one. So i tried at least two different single vactrols on the left spot. The result with only one vactrol on each channel was lacking compression on one channel, no matter what vactrol i used on that channel.

I just did a diode test: 3 vactrols show values of 510-560 on the multimeter. My mulitmeter shows a 1 in standby, which remains when checking those 3 vactrols, so it in fact displays 1510 to 1560. Checking the 4th vactrol, the 1 disappears, so it only shows a value of 550. this seems to be the problem. with two vactrols soldered in on each channel, on one i have 1170, and on the other 1560. Gonna call Musikding tomorrow.

i'll double-check this again. i already have a solder-massacre going on at those points... (the problem however is not with the broken solder points, as i always checked the traces up to the next point).

seavote, are you saying that one channel influences the other? i assumed they are autonomous.

thank you guys a lot for the input!! that kept me going. much appreciated!

 

[seavote]

"seavote, are you saying that one channel influences the other? i assumed they are autonomous"
no i was not saying the channels would influence one another. i was saing if you had one vactrol on the right channel and two on the left. and one vactrol on the left side was faulty the unit would process(compress) only 1/2 the audio signal on both channels and give a balanced left-right signal.since you reported this was the case with your DAOC i was using it to support my theory.but unfortunetly i was incorrect

 

[mischa]

vactrol changed -> all is good.

happy compressing 

 

[dagoose]

MM, yes, i had them like kubi wanted, one facing up and one down. Also, Musikding delivered two pairs with different numbers: one pair has 511 written on it and the other one 636. must be the batch number.

\

I think that it has something to do with the batch numbers, i had something quite similar with mine. Both channels worked fime but it had quite a big difference in left/right in character. I had different batch numbers as well.
Replaced them with new ones and it's great now!
Have to check the wrong batch numbers if i still have 'm..

 

[mischa]

...I think that it has something to do with the batch numbers...

in my case it had not much to do with the batches, because one vactrol from batch # 636 had a grossly different value than the other one from the same batch... got a third from the same batch from musikding for free, and it had pretty much the same value as the 636-batches as well as the 511-batches.

all this referring to the diode test with my dmm... don't know which other differences are possible with those parts.

 

[Eje2005]

Not really sure were to put that meter resistor, does it matter if its in series with - or +?  :-[

 

[[silent:arts]]

putting it at + works fine

 

[Eje2005]

Thanks! this is what i did, but i get some weird behaviour, will take some measurments tomorrow in the studio.

But it sounds Damn good!

 

[Matthew Jacobs]

Anyone got some NE2 to sell me?

Or any 1N5371?

Can't find a source in UK or in Europe for that matter. And ordering from the US was gonna cost me $34 for components that cost $2.90

Or does anyone have a UK / Europe source for these babies?

I'm also thinking of using Sowter Transformers, and these + the NE2 / 1N5371 are the only components missing for my build.

Can anybody help?

JD

 

[[silent:arts]]

http://www.conrad.de/goto.php?artikel=725200
this is what I use

 

[Matthew Jacobs]

Thanks bro!

Checked everywhere else but forgot about Conrad.

Sorry if this was already in the thread somewhere. MartyMart, maybe you can update your BOM as it was really helpful for me and I'm sure it will help others in the UK / Europe.

Cheers

J

 

[Matthew Jacobs]

I've decided to go with Sowter 4383 transformers on the input and outputs. First time I'm gonna use Sowter.... We'll how it goes....

J