D-AOC PCBs - the building and help Thread

[druu]

Hmm, do you think the diode would work ok instead?

Ya - ditch the neons. They suck. And 'ping'.

Get some zeners - 68V, 1W or something like that, if I recall.

Check the detail and get the nearest.

I used neons once. Then tossed them.

Alex, would these be ok?

http://australia.rs-online.com/web/p/zener-diodes/6256473/

 

[alexc]

yep - thats fine

As I now recall, I did use 5W also.

 

[mitsos]

Are the 47uF/400V caps really necessary? I have a bunch of 10uF and 22uF, 450V from other projects, would 22 be OK here? 

cheers!

 

[mitsos]

For those who have done the Slope switch, is this more or less how you hook it up?  The LEDs/Rs are in no particular order yet.

thanks

 

[dipfrik]

Maybe i can raise the bar a little bit…what about an Arduino based TROM ("total recall option mod") for saving, restoring and A/B'ing different treshhold and slope settings?  ;D

I know, why my mother spend so much money in my education! …need more "Kaltgetränke"  8)

Cheers, Sven

...and yes, this is a not finished D-AOC in a 1RU height case with a reversed Gssl Frontpanel from Frank

 

[thomasdf]

I was planning on building a LA2A with a different sidechain and somebody pointed me the D-AOC... Looks very tempting.
Has anybody tried to build a single channel on PTP?
I have an old chassis that I would like to use.
Can I get rid of the input transformer?

 

[thomasdf]

bump!

 

[Lowfreq]

I'm just about to set up my "slope" switch with the different leds & resistors, but I also want to include the kubi mod (extra vactrol) which I currently have installed. Is it as simple as lifting the positive & negative legs on the paralleled vactrol, and attaching that to the switching system? Or do I also need to lift the three legs on the photocell side also?

If that's working as an LDR will it still affect the other vactrol if those 3 legs are still in parallel with it?

 

[MicDaddy]

Hm, if so, C104 is better as high in value as possible. 1uf fits if legs are bent or extended.

ALT HPF IDEA: How about an RC filter (stable corner freq.) between wiper of SC In pot and before the SC tube stage?

^ interesting, what implications would this have on the ecc82?  This would be an unbalanced (maybe incorrect terminology, having been doing maths for balanced HPF for another project) RC correct?  Could you put it on a pot & switch so that your R would be variable and the whole thing could be bypassed? 

 

[jensenmann]

Can I get rid of the input transformer?

The original DAOC did use  10k:10k trannies at the input. No gain there, only debalancing. I cannot see any reason why it should not work with an unbalanced, ironless input.

 

[MicDaddy]

Hmm, do you think the diode would work ok instead?

Ya - ditch the neons. They suck. And 'ping'.

Get some zeners - 68V, 1W or something like that, if I recall.

Check the detail and get the nearest.

I used neons once. Then tossed them.

Alex, would these be ok?

http://australia.rs-online.com/web/p/zener-diodes/6256473/

The Zener called for on the board is 1N5371 or 60V

The Zener linked here is a 1N5373  68V

 

[MicDaddy]

What is the dc voltage at the output cap?

Am I ok with a 250- 10uF WIMA from the pm660 build?

I'm thinking of parallel with the 10uF Solen just for the hell of it on one channel and seeing if I like.

 

[alexc]

The output cap should have a voltage rating exceeding the 'start up' B+ voltage at the finals.

So - if you have a B+ that starts at 300Vdc unloaded at startup, that then drops down to say 250V loaded,

you still need 300V rating  min at that cap

(or any other which is in the 'line of fire' -  until tubes begin to conduct and the psu droops an amount determined by it's 'stiffness'.)

 

[alexc]

I think I was reading about doing a microprocessor based sidechain for this build? (arduino thingy)

A great idea - this limiter could be great with a digital sim of the vactrol. They do tend to be all over the place!

Unless you have that most great of tools, a transfer function (magnitude only even!) curve drawing app, it's painful to characterise what's going on, dynamic response wise.

The attenuation, pre and finals of this build are really fine. The GR character is also cool. But hard to match or quantify the differences between commonly implemented 'modes' 

ie. anti parallel led or whatever persuasion, resistor and/or cap timing and so on.

So - one of them fancy pwm sidechains on this guy please. For 'poor man tubey mastering' 

Sounds like a job for Abe !

 

[petermontg]

Any problems using metal oxide 5% for 2W. lower tolerance, more abuse etc etc

 

[MicDaddy]

The GR character is also cool. But hard to match or quantify the differences between commonly implemented 'modes' 

ie. anti parallel led or whatever persuasion, resistor and/or cap timing and so on.

hey alexc,  what value of cap did you use at Cx04?  Kubi spoke about using a larger value?

From Kubi  "Increase Cx04 from 100nF to whatever you can maximally fit on the PCB. 220nF was the biggest cap I could insert. I wish there was enough space for 1uF, but real estate was too precious on the PCBs and Volker was too stingy with the real estate. Anyway, the diode within the vactrol is a variable resistor which forms a CR highpass filter with that cap. If you increase the cap, the filter frequency lowers and the compressor becomes more sensitive to lower frequencies. Yes, I know everybody wants a highpass switch for side chains like the GSSL's, but you don't need it here, 100nF is too small for many applications. Even worse: If you push the compressor harder, more current goes though the diodes and the resistance lowers so that less compression happens - quite inept, isn't it?

Don't worry, if you double the vactrols the resistance from two parallel diodes does not become lower, because only one diode conducts at a time, thus the other diode becomes an infinitive resistance for the period of a half signal wave (apart from the leakage current). "

I was able to fit 1uF on there with a little creativity.  I don't know what EMC problems this bring as the caps leads are longer now (inductance) and they are floating some above the board (capaditor antenna?) ,  I will soon find out.....

Anyhoo, I'm hoping to push that CR pole waaaaay down so that the interaction of the LED varying resistance with that cap won't cause funny business with what material gets compressed...  probably not explaining that as elegantly but I think I understand what Kubi was trying to say?  Maybe it's too early and coffee too strong..  Then it may be possible to implement a HPF prior to that tube stage for the sidechain?  I'm thinking.... somebody point me right.

 

[Miska]

Hello!

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

 

[Miska]

Bump...

 

[druu]

Miska, I have one I'm not using, brand new and unused from Musikding. I'm in Perth, Australia though. PM me if you're interested.

 

[thomasdf]

Banzai carries some of these, and is in Germany too