[Nic Rhodes]

I am a bit confused and wonder if someone recognises anything here.
 
I bought a Darkvoice 337 advertised as the 2010 version. I have been using it for some rolling and have had some very impressive results [with TS Mesh 6SJ7GT and RCA 5693]. It is far better than I was expecting. Condition was excellent and was supplied with  an adapter with an EF184 driving a Russian 6N5S / 6AS7G originally. The front and back say THA 337 [no mention of se] however....
 
The manual looks like this:
 

 
 
As it was a few years old now I thought it worth checking the 'yellow' resistors and this is what I found:
 

 
 
The resistors in the centre are faded and there is some burning on the wires so they will have to get changed [working fine atm], more on that in a minute. There are obviously 4 extra silver capacitors that have been added. [They are at the bottom, either side of the tube sockets]. The general layout seems different to what I was expecting and much closer the internals of the 337se on the Darkvoice web site, piccy below:
 
http://www.darkvoice.net/en/intro.asp?loca=173&a=764&tlb=3&js=2&id=1369
 
 
Which model do you think I have? A 337 or 337se?
 
Now as I thought I had a 337, I went to parts cupboard and found some 470 ohm yellow 25w resistors [original resistors are 430 ohm 25w] but I also found some green ceramic resistors I can't remember where they came from (likely to be better quality). They are also 470 ohm and marked W24. Does anyone recognise the make? or think they might be a suitable alternative. However if I do have a 337se (2010 model with low serial number] then perhaps I should shell out for some of the best resistors instead, if so what are the recommended ones please? Replacing them myself is no problem, it is just what I found today is not what I expected to find!
 

 

 
If it helps, my '337' has open mesh sides and 'premium looking quality' side panels as opposed to punched chassis. It is below:
 

 
 
My machine looks similar to this old advert [but mine with added Caps]
 
http://www.aliexpress.com/item/Dark-voice-337-Headphone-Tube-AMP-Amplifier/438657518.html
 
which list the machine on the back as an se, but is without my nice side panels.
 
Confused from Cumbria! Can anyone with more experience of this amp recognise anything that might this mystery. I can believe I have a modded 337se!

 

[kramer5150]

They have made running design changes through the years.  FWIW mines an original 337 with the original green ceramic power resistors.  So yours is definitely not to the original specs.  I couple its output with speaker transformers and it sounds incredible with all my cans.
 
Biggest problem with these amps is that they under-spec those gold aluminum resistors and they overheat an early death.  In those circuits everything up and down stream of the resistors is exposed to very high temperatures that conduct through the P-P wiring.
 
Google search "darkvoice 337 resistor failure"... it will take you to another forum where its moderator did a successful part upgrade to a better resistor value that could handle the wattage/heat.
 
 
FWIW heres my original spec.

 

[Nic Rhodes]

was that the Rock groto forum?, if so I am aware of that UK thread when it happened but it didn't help any? They struggled to get a solution. Changing a resistor is easy regardless of quality, what I have here is more difficult! It is a mystery.
 

http://rockgrotto.proboards.com/thread/5703

 
 

 

 

 

[kramer5150]

Did you see the second page of the thread?  Although I just noticed yours is one of the newer component layouts than the one discussed on the RG forum.
 
One of the amps owners posted this:
"Just a quick update guys.
Manage to make contact with one of the people who used to work at Darkvoice and he has advised me to replace the resistors with 2x 25w 1k ohm in parallel each side.Got some Vishay ones on order.
Should arrive monday,will keep you posted."
 
 
And then followed up with this:
"Fitted parts last night and had 2 hours of blissful listening 

 before tiredness kicked me upstairs to bed.
Amp still runs hot as a person but thats the nature of the beast.So far nothing smells out of place,fingers crossed thats how it's going to stay.
Can't thank you all enough,especially Mike for giving me the confidence to repair it myself 

Regards ####"

 

[Nic Rhodes]

Thanks for your help.  It is a simple fix I think. Do you know whether this is a 337 or 337se? This probably effects how I mend / modify it?

 

[kramer5150]

  Thanks for your help.  It is a simple fix I think. Do you know whether this is a 337 or 337se? This probably effects how I mend / modify it?

I have no idea which one yours is.
 
Two things are certain,
1) Yours is definitely not an original release layout like mine.
2) Yours is not one of the earlier layouts like the one on the RG forum, with the 3x resistors bunched together.
 
 
If I had to venture a "wild guess" yours is closer to the SE model... but there's really no way of knowing for sure.  Those gold resistors are wattage rated when properly mounted on a chassis / heatsinking surface.  The way DV suspends them like that is not recommended.  The other thing I did was I added a pair of small 5V DC fans to my amp bottom tray.  I don't always run them though, I turn them on after a couple hours.