D-AOC PCBs - the building and help Thread

[druu]

Yes, as above, I was measuring the secondaries from a common earth but the 24v secondaries on PSU3 don't share the same earth, hence the zero reading.

I'll try reduce input voltage of the 300VAC i'm getting from the 250v secondaries. Thanks again for everyones '101'.

 

[[silent:arts]]

Yes, as above, I was measuring the secondaries from a common earth but the 24v secondaries on PSU3 don't share the same earth, hence the zero reading.

depends. put the jumper in:

 

[druu]

Thanks Volker. The funny thing is its one of the first things I noticed when I first received the pcb. Was well hidden to me after populating though.

 

[Nescafe]

Hi,

Is there any possible mod to put a high pass side chain for this comp?

Thank You.

 

[Script]

HPF = opposite of Kubi mod in the sidechain.

 

[Nescafe]

Hi Script,

I have read that, Thank You for Your information.

Is there any other posibilities other than Kubi mod? Have several possible freq hpf (that we can calculate) will be make this comp far more versatile in any other situation 

Thank You.

 

[Script]

HPF

Higher cap value = lower HPF corner freq.
Lower cap value = higher HPF corner freq.

So,
Put lower cap value (for highest desired HPF corner freq) in position on board,
Put higher cap value (for lowest needed HPF corner freq) in parallel on switch.
Engage switch for no HP filtering.
Disengage switch for HP filtering.

I'd first test how different cap values sound before drilling faceplates.
Caps should all be of the required voltage rating (maybe a bit costly).

I haven't tried this. So don't sue me

 

[Nescafe]

Hi Script,
that's a great idea, once again Thank You, I just not patience to do trial and error approach  ;D

 

[Script]

Not sure though how far we could take it here. I'm not a tube wizard -- actually, to me tubes are a kind of expensive low-illumination light bulb with distortion behaviour  :

We better did some research on tube electronics. Or someone who knows their tubes could please chime in. Would too low cap values eventually mess with the circuit?

 

[Nescafe]

;D ;D ;D Script.........this is my first tube project too, I don't know about tube but I read that this is a good sounding equipment, so I give it a try, so wish me luck. Now I search to find the suitable power transformer, very hard to find in my country 

 

[Script]

From what I read (about tubes) and deduce, tube distortion should be very low in this unit, almost negigible. I guess that feedback around the tubes linearizes them into rather "clean"-sounding amplifier stages.

Last time I looked at the comp (more than 6 months ago) it measured voltages fine but hasn't passed audio yet. I'm a very slow builder. Too many projects, too much reading

 

[Nescafe]

From what I read (about tubes) and deduce, tube distortion should be very low in this unit, almost negigible. I guess that feedback around the tubes linearizes them into rather "clean"-sounding amplifier stages.

This is the reason why I try to start this project

Last time I looked at the comp (more than 6 months ago) it measured voltages fine but hasn't passed audio yet. I'm a very slow builder. Too many projects, too much reading

groupdiy syndrome  ;D

Any info what balanced  I/O is working good with this DAOC? I don't want to use transformer I/O.

Also any power transformer source info will be very very appreciated since I lived in 220V country, most of the supply I can found is have 230 primary so I think better get higher 250V/12V secondary to compensate.

Thank You.

 

[Script]

Would too low cap values eventually mess with the circuit?

Remembered the position of that cap wrongly :-[  The cap is after the SC tube stages and before the Vactrol. So no messing with tubes (if any at all!?), but messing with optocoupler. Kubi mod says:

"...the diode within the vactrol is a variable resistor which forms a CR highpass filter with that cap... 100nF is too small for many applications. Even worse: If you push the compressor harder, more current goes through the diodes and the resistance lowers so that less compression happens..."

Meaning: apart from changing the resistance on the receiving side of the optocoupler (shunt to GND btw. R102 & RV101) for volume attenuation, the corner freq of the filter (on LED side of optocoupler: C104 & resistance of opto diode) itself is not fixed/stable but varies in resistance due to current? Interesting! Meaning the louder the signal, the lower the resistance in the diode and thus the higher the corner freq.? It constantly adapts, but by how much? In the worst case scenario, if corner freq. extends too far up into the audible freq. range (because of low C104 cap value), then "less compression happens" ultimately means that louder bass signals (higher current pushing up corner freq higher) get less compressed than quieter bass signals of same freq. below filter corner freq.?

Shot me or is it my head? Should I consult with a doctor or with beverages from the fridge? 


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?

 

[druu]

Also any power transformer source info will be very very appreciated since I lived in 220V country, most of the supply I can found is have 230 primary so I think better get higher 250V/12V secondary to compensate.

Thank You.

Musikding will be getting more 'ring250' toroids in so maybe send them an email.

 

[alexc]

Also any power transformer source info will be very very appreciated since I lived in 220V country, most of the supply I can found is have 230 primary so I think better get higher 250V/12V secondary to compensate.

Thank You.

I have for sale a Musikding psu traffo for the doac in the black market - built one already and won't be using this one.

http://www.groupdiy.com/index.php?topic=52808.msg673461#msg673461
Cheers 

 

[druu]

I'm trying to sort the wiring for the input and output transformers at the moment and could use some help! I've never wired audio transformers in alternative configurations and trying to get my head around it.

I'm using LL1540's for both input and output. Input I have wired as 1:1 as follows (please correct if I'm wrong) - Refer to here for pinout http://www.lundahl.se/pdf/1540.pdf :

Primary: pins 2+4 tied, pin 1(+), pin 3(-) - From Bypass board XLR
Secondary: pins 5+7 tied, pin 8(+), pin 6+pin E(-) - To PCB

For the output (also LL1540) I wanted to wire reversed 2:1. I have the following:

Primary: pins 8+5 tied as (+), pin E to ground - From PCB
Secondary: pins 2+4 tied, pin 1(+), pin 3(-) - To Bypass PCB

Does this look about right? Any advice appreciated before I finalise the soldering on the prototype boards that hold the transformers. BTW i'm not using any additional resistors as the spec sheet says, should I? Thanks!

 

[druu]

Anyone?

 

[dagoose]

I think I also did it like that though not sure, i haven't wrote it down or anything like that.
If it works OK, it is OK.  8)
But maybe someone else can chime in?

 

[druu]

Thanks Jeff. Hopefully i'm on the right track! Thank you in advance to whoever can assist.

 

[druu]

Is it possible to switch between GR signal and Output signal for one channel using just one pole? I'm thinking not but would be good for confirmation. Thanks!