D-AOC PCBs - the building and help Thread

[Pusch3l]

I stick with Frank from Frontpanels.de and i think the other German Guys here too..

 

[audiophreak]

Hello All,
                I'm about 2/3 completed with this project including the Kubi Mods , Can someone point me to where I might find info on how to hook up the " Curve " LEDs when using two Vactrols,  I've seen a couple pix of others builds, but they only had one Vactrol installed.

  Thanks in Advance 

 

[Hobbyist]

Hello All,
                I'm about 2/3 completed with this project including the Kubi Mods , Can someone point me to where I might find info on how to hook up the " Curve " LEDs when using two Vactrols,  I've seen a couple pix of others builds, but they only had one Vactrol installed.

  Thanks in Advance 

Excellent question ! I'm in the same situation here.. 

Actually there's an advanced unit from the user protools,  looks like the second vactrol is installed with a separate switch..  But it's hard to see how they're connected.  I guess in his version it works like vactrol 1 + leds + switchable vactrol 2 but i'm not sure..

tnx

 

[protools]

Yes i confirm, they are in parallel with the switch doing on/off on the second one.
Best
WT

 

[Hobbyist]

Yes i confirm, they are in parallel with the switch doing on/off on the second one.
Best
WT

Thank you so much for sharing 

 

[audiophreak]

Yes i confirm, they are in parallel with the switch doing on/off on the second one.
Best
WT

  Thank you !!  , I'm still a little confused on the actual wiring of LEDs and second vactrol , but will study/search for a while and formulate a better question  ;D

 

[justinheronmusic]

Would this Cinemag transformer work as input transformer for the D-AOC?

http://cinemag.biz/line_input/PDF/CMLI-600-600C.pdf

 

[audiophreak]

Hello All 

      Ok , I did some searching, found the info link on the curves and LEDs , just looking to confirm ( and one member stated ) that using the LEDs and resistors  replaces the necessity of using the second Vactrol ? or is this in addition to.. ?

    Also I have powered up to do the voltage point tests listed in first page , and got -
    243vdc / 244vdc at R128/228
      62.3vdc / 63.2vdc at `R127/227
    222vdc / 221vdc at R111/211
    242vdc / 243vdc at R105/205
    177vdc / 206vdc at R118/218

      Valves installed,  I double checked resistor values at all points associated with those traces , all are good, so I am assuming these readings might be because I don't have the input and output pots and transformers hooked up ??

... any suggestions


EDIT :    Yes , That was it , installed and wired Pots , all voltages are good now !!  ;D

 

[protools]

Additional...

 

[audiophreak]

Additional...

  Thanks !!  ... and the with both Vactrols that would be highest sensitivity ??

 

[Jonkan]

Im trying to get my meters working correctly, but I am having some issues.

Im using 1ma dc meters and i was under the impression i needed a buffer/rectifier for these so I added some  jlm vu buffer kits.

I can get the meter to react to signal, and it shows gain reduction, but I cannot ever get the needle to go above even the halfway point of the scale, even tho i have tried changing both the meter trim pot on the daoc pcb, and the trimpot for the vu buffer pcb.

Any ideas what i need to change to get this working? The meter is happily boucing around without the vu buffer, but I suspect the ballistics are not very VU like in behaviour like this? I cant get the needle pointing above straight up here either (not sure what is normal behaviour for this gain reduction meter circuit?)

What would you do?
cheers,
j

 

[Jonkan]

I have decided to just get some proper VU meters instead of fiddling about with this crap. Any good EU sources that you know about? Otherwise I'll probably order from Hairball audio, they seem to have some different meters to choose from.
/J

 

[[silent:arts]]

Many VU Meters in Germany

 

[Jonkan]

So I bought some of these:
https://www.don-audio.com/Vintage-Meters-VU-Meter-VM2103

If I just want to measure gain reduction and not output VU (im guessing the ballistics are off anyway), do I need a 3.9k resistor in series with this meter or just connect straight to the daoc pcb?
(also the shop homepage says to use 3.6k for this meter?)

Or, do you feel output Vu meter is worth it to implement?

Thanks for helping me!
/j

 

[Jonkan]

Sorry for all these questions!  ;D I was  just curious from where  you other people that did use a switch from  g.r  to output meter level tapped  your signal  from the output? Before or after output Transformers? Any particular  spot which is better to tap  the output signal from??

I have it up and running now with only g.r metering together with a 3.9k resistor in series,  so that is a good start. Needles are moving at least and goes  to zero  without any gain reduction going on.

Dont  know if gain reduction is tracking correctly at all yet. I dont have a trimmer in place for r126/r226, so I can only adjust rv104 and  rv204 for zero:ing the meter, right?

Update!: I can get the meters to show gain reduction when sending a sinus tone into the compressor, but they never show the same amount of reduction, ever even though the signal is the same! Its not even close!

Does this mean i need to install some trimmers instead of r126/r226??

Also should I use a 3.9k  or 3.6k resistor in series with the vu (opinions seem to differ here?)

I  kind of wish I didnt  take an eight year  break with this build,  but sooooon its actually finished, lol!  ;D

 

[Hobbyist]

It's still grungy but finally works ! It has 2 sets for the curves, 3th and 4th Vactrol are as an addition in parallel and some of Kubi's mods.... It sounds awesome ! I used a quad of 5814 tubes for in and out and some RTF's for the side chain.. no complains so far.. I'm not 100% sure about the connections from the Lundahls LL1540 on the input.. it works fine except I need to push hard in to get compression. I tested with different stepped attenuators to check out..


Thanks to everyone for the inspiration !
Bless this community !!
;D

 

[Hobbyist]

.. another picture

 

[[silent:arts]]

Nice

it works fine except I need to push hard in to get compression

try to wire your LL1540 1:2 for 6dB more input level

 

[Jonkan]

Ok,  I read the whole  thread like two times and  I now know  I need  some  trimmers  for accurate:ish  gain  reduction metering. 

Also  im having  this issue where the unit it pretty matched in dual mono ,but way  off in  stereo linked mode.

Attached a picture to  show the difference. This is at max  compression 1k  sinus tone into the compressor.

Im using  dual vactrols ala kubi btw.

What I have understood so far  is that i need to install trimmers  on the anode of  the  vactrols. Is  that  correct?
Trimmers  on both vactrols or  do it  like Holger and  just trim one of them?

If I trim  the stereolink  to better match, will my dual mono balance be way off instead?

/J

 

[Script]

Easiest (cleanest) fix is to use the unit in MS mode, not linked stereo.