D-AOC PCBs - the building and help Thread

Well !!! This one is perfect for the DAOC :
http://www.musikding.de/product_info.php/info/p1361_Toroidal-transformer-230V----250V--9V--24V.html
Really interresting seller  :

Transformer question :

I'm not too "Up" on transformer usage etc and I'm wondering if I need a zobel network
on my D-AOC.
I can't seem to hear any issues right now, On inputs I have LL 3815 ( 1:5 ) and LL 3814 ( 3:2 C large C core )
on the outputs.
There's very limited info on these from Lundahl, just a pinout sheet really, I have them wired direct between
XLR's and board inputs.

Any thoughts welcome, it seems to sound fantastic and is quiet and hum free also.

MM.

most (or all ?) Lundahls are Zobel free

MartyMart said:

Any thoughts welcome, it seems to sound fantastic and is quiet and hum free also.
MM.

Click to expand...

"Never change a running system". Congrats to your D-AOC.
regards
Bernd

I decided I wanted to figure out the compression ratio(s) of the DAOC.  I did some measurements. I am using a VTL5C2 so I'm not sure if it's the same as the VTL5C4.

I started by using a 1k tone at +4dBu. I adjusted the threshold until I had 3dB of compression. I wanted to get away from the knee to start. Here is what I measured. The first column is input level and the second column is output level.

+4 = +1
+6 = +1.8
+10 = +2.4
+12 = +3
+14 = +4.2
+16 = +5


Here is what I measured starting with an input level of -14dBu. Starting with 3dB of gain reduction like above.

-14 = -17
-12 = -16.4
-10 = -15.6
-8 = -15
-6 =-14.3
-4 = -13.4
-2 = -13
0 = -12.2

When I got the first set of numbers I thought the compression ratio was 2:1 because the ratios were close. But the second set of numbers didn't come close. I noticed that in both ranges for every 2dB increase at the input I got a .5dB increase at the output. That looks like a 6:1 compression ratio. Does a compression ratio refer to the voltage ratio? My math is really bad. I'm confused.

Anyone can make photo from the toroidal transformer from musikding connected to the Daoc pcb ??  Just to be sure ...
Before i kill myself i want to be really sure of the connection from this transformer

Thanks 

have a look at the d-aoc pics in the middle of the first post in this build thread:
http://www.groupdiy.com/index.php?topic=29854.0

hth, christoph

Hi,
I finished building the compressor and the result so far is a big failure. I made the right channel works correctly but the left channel there is no way that works.
The signal is passed correctly and arrive on the output, but the compression works only a few seconds, after this period of time the effect compression disappears, the vumeter returns to 0 value, meaning it is in bypass status.

A curiosity is that when I put the compressor in link mode, the channel left compressor works, but does so to a lesser extent than the right channel. I tried several different vactrols quite the same result, it is as if the right channel operates at 100% compression and the left channel only 50%. This is something I am confused.

All voltages of the circuit in both channels are correct. I changed all the pots, cables, valves, transformers, the Vumeter and the vactrol. I have checked all the capacitors are working correctly and it seems that there are no false contacts. The point is that I no longer know what else to do, I think it can not be changed more objects, but the left channel of the compressor still does not work. I do not know what can be wrong ... Does anyone have any idea to solve this whole issue?
Thanks for the replies.

Is any of the antek transformer models suitable for the D-AOC, assuming that you will use an extra small toroid for other duties if a third voltage is required? i mean, all of the tube models are 6.3+6.3v, and connected in series gives 12.6v, but the D-AOC are expecting 9V...

Have finished My Daoc!
Take a look.

Regards

http://www.groupdiy.com/index.php?topic=32714.0

Well, after more than 120 hours of attempted solution, I am unable to run this thing ... the left channel does not compress. This is long time, overdue and I am not determine what is the problem. I disassembled the compressor up to 8 times! And always get the same results. It really is desperate, so I give up. White flag ...
Here is the schema with the values of the tension I have in the pcb.

If anyone can get an idea on how to solve this problem continue to get it to work correctly, I will try. Otherwise I think I will make a bonfire and burn in the fire...  :

Delaymix - first DO NOT give up on this !!
I'm sure that we can get it working with all the HUGE brains here :-0 ( mine is only medium sized !! )

So, your voltages look quite similar to mine which is working, the only one that seems a
bit low is the voltage @ R127 from the 1N5371/NE-2 you have only 51.6v on the left side.
Both of mine are nearer 59v
You say that one side seems to go into "bypass" and the meter rests back at zero, so are you
sure that you don't have a problem only with the "Bypass" board with the relay ??
Worth checking that out I would think.
I'm sure that Volker and others will "chime in" with suggestions also.

MM.

Thanks MM. I'm still investigating to try to find out where the problem might be, but for now I have not made any progress.
When I refer to the left channel seems to work like you are in is because the bypass machine works, but does so completely in the absence of effect of compression.
The relays are all successful, or so it seems, work well, I have reviewed and tried to make sure no problem.
I am using neon lamps NE-2 instead of the 1N5371 diode.
An example to explain this a little better if you adjust the input level to ¾ of their total value or the maximum and the threshold of a compressor or ¾ full, then the left channel is behaving exactly as if the compression threshold was adjusted to its minimum value. The sound goes and everything is correct, but the sound is not compressed at all, just makes it a little when the switch link is activated.

Well, I have continued searching to see where is the problem, but I still do not know what is the reason why the left channel does not compress. I think the problem is in the area of the side-chain because the impact is just as you remove the valve side-chain, the signal passes, but not compressed. However, I changed my valve, it could be a problem for the valve, but the problem persists. I'm using the ECC82 are new. All the resistors I used in the project are of metal film with a tolerance of 1%, capacitors WIMA and Solen, electrolytic 105 º. The assembly is clean and neat. Beginning to suspect that the problem lies in the PCB.
Could have gone bad and have a track with any manufacturing defect or crack and all that be the cause of this problem ...
Any idea or suggestion from anyone is welcome to try to make the compressor work properly. Thanks.

delaymix said:

Could have gone bad and have a track with any manufacturing defect or crack and all that be the cause of this problem ...

Click to expand...

would be the first time, they come "electronically tested" (whatever that means)

what do we have ?
- both channels pass audio ?
- one channel doesn't compress ?

anyhow, how I would proceed:
- take the tubes out
- compare resistance values between the working and not working channel, mainly in the sidechain and around the vactrol
- if there is a fault (either component or PCB) you should find a difference

my first bet is the vactrol  ...

Thanks silent:arts, as to a possible problem in the PCB is only a guess of mine, I'm not making a statement that it would be very difficult to prove. In case there was a crack could have been done during transport, handling etc ...
As explained above eight post (on previous page) I also changed the vactrol. In fact I have six available vactroles but the result is the same. To clarify this a bit more, I have changed:
Vactrol, valves, cables, input transformer, output transformer and pots. The result remains the same, and the tensions of work remain unchanged. (Schedule the voltages in the PCB of previous page).

delaymix said:

As explained above eight post (on previous page) I also changed the vactrol. In fact I have six available vactroles but the result is the same. To clarify this a bit more, I have changed:
Vactrol, valves, cables, input transformer, output transformer and pots. The result remains the same, and the tensions of work remain unchanged. (Schedule the voltages in the PCB of previous page).

Click to expand...

sorry, I don't have anybody's individual troubleshooting and history in mind all the time :-\
will send you a leftover PCB from the white christmas edition.
but never less, don't give up
the replacement PCB would be a restart.
finding the fault in your existing build would be a success experience.

Thanks for you response. You are absolutely right. I assure you I would find where the problem. This is the most bizarre I have ever experienced. Nor is my first project, this cost me understand what is failing. I also checked one by one all the components of the left and are exactly the same that is on the right side. Cases like this are a bit frustrating ... ???

smal question before ordering the rest of the parts for this toy!

I've got the Tx from Musikding so 250v/24v/9v.
what value for c11/c12/c13?

Lolo-m who whas kind enough to share is Bom with me, listed c11 @ 4700uf, c13 @ 100nf and nothing for c12.

for those who used this trafo, can you give the correct value you've used please...

thanks.
Jr.

delaymix said:

Thanks for you response. You are absolutely right. I assure you I would find where the problem. This is the most bizarre I have ever experienced. Nor is my first project, this cost me understand what is failing. I also checked one by one all the components of the left and are exactly the same that is on the right side. Cases like this are a bit frustrating ... ???

Click to expand...

Don't you have a break in one of the printboard-traces or maybe a short? If all parts are OK it must be somewhere else in the circuit..
This kind of stuff is indeed really frustrating.