Darkvoice 337 - A Review - Page 7

I was comparing the 337 and the 332 actually. I have never heard a DV336. I apologise for the confusion.

Also, I wanted to bring this to everyone's attention. You can find the entire inside picture on the first post in this thread. I've cropped and labelled a subset of that below.



The socket I've labelled is the underside of my DV337's 6AS7G tube. The 6AS7G is a double triode. Notice the outputs are paralleled? That means both of the triodes are wired together to the headphone out.

To put this in perspective, to achieve this layout on the 336, you would need two 6AS7Gs instead of one. In the 336, only one triode is used per channel.

In the 332, each 6C19P tube is a single triode. So again there is only one triode per channel.

The 337 differs from the 336 in that it uses one entire pentode (6SJ7) to drive two triodes (one whole 6AS7G). The 336 uses 1/2 of a twin triode (6SN7) to drive 1/2 of another twin triode (half a 6AS7G). The 337 also has twice the power supply capability of the 336.

The 337 is similar to the 332 in that a single pentode (6AK5) is doing the driving. However, it differs again in the output where it has only one single triode (6C19P). Also, just like the 336, it only has one power supply.

So what exactly are you paying for in the price premium of the 337?

1. One more power transformer (these things are expensive)
2. One more power supply (those high voltage electrolytic filtering caps are also expensive)
3. One more triode output section per channel
4. The fat 51uF SCR (Solen) output coupling capacitor per channel.
5. The larger case, more intricate wiring and metalwork

Is the increase in sound quality worth it? It's up to the owner. The extra output triode section on the 337 would allow it supply more current to low impedance headphones. Cans that don't sound so hot on the 336 and 332 would probably fair better on the 337. However, since the lowest impedance headphones I have (JVC DX1000) bottom out at 64ohms, I cannot substantiate any claims about superior low impedance performance.

What I can say is the DV337 has a huge range of tube rolling possibilities. It sounds amazing. It's got presence. It's rare. And I love it.

As an aside, the closest competition to the DV337 would actually be that dual mono DV336 Fitz created a while ago. The costs of both are similar.

First things first, it's "Doge" not an American car manufacturer.

You've got three different topologies right there. The 337 is a cathode follower OTL. The Bada is a tube-mosfet hybrid. The Doge is a traditional transformer coupled tube amp.

The reliability of the Bada in itself would discourage me from buying one. I used to own a FEEL HP200SE, also a tube-mosfet hybrid. They're good no doubt, but I think it's less fussy to stick with either all tube or all SS.

If you want that "traditional tube sound" go with the Doge. The non-linearities of the output transformer colors the sound, but not necessarily in a bad way. If you look at post #10 by cotd, he goes into some detail about the Doge vs. 337. My opinion conforms with his.

The 337 OTL topology sounds more solid state than valve based. If you have a chance check out this article on TubeCAD. The cathode follower circuit produces very little distortion and low output impedance at the expense of low gain. Fortunately this isn't a real problem with headphones. If you have more time, read up on OTL power amps such as the original Futterman or the Circlotron. The general consensus is that these amps don't sound at all like traditional transformer coupled amps. I believe this is mirrored with OTL headamps.

I think the best thing to do is audition all three amps and let your own ears decide. Though I can't really help but plug the amp I own, hehe. Go for the 337!

You can talk to the manufacturer directly on his administered forum:

http://www.diybuy.net/forumdisplay.php?fid=28

I doubt you will be able to go balanced. You would need to make significant circuit modifications.

I've ABed both (using mainly DT880s). The difference is not really very large. You do have many more tube rolling options with the 337. There are only three manufacturers of the 6C19P power tube, versus a huge handful of 6AS7, 6080, 5998, 6336, 6528, etc.