Darkvoice 337 - A Review

[Gradofan2]

So... is Mazuki comparing the DV337 to the DV336... or the DV332???

I could understand his comment... if its the latter comparison...

The DV337 should be only "slightly better" than the DV332... but... it should be a lot better than the DV336.

[nick20]

Originally Posted by Gradofan2

The DV337 should be only "slightly better" than the DV332... but... it should be a lot better than the DV336.

For that price, I would except the 337 to be "a lot better" than both the 332 and 336.

The 337 is twice as expensive as the 332, and two and a half times more expensive than the 336.

[tomjtx]

Originally Posted by NoPants

have you guys tried the 337 with low impedance headphones such as grados or Audio Technicas? As I understand it darkvoice/tube amps have higher output impedance than normal and don't power these low impedance headphones effectively

Isn't the AKG 701 low impedance?

The 337 powers my 701's beautifully.

I'm listening to a Stravinsky symphony now and I just had to turn down the volume . This amp has an astounding dynamic range and it gets the macro and micro dynamics right. There is a feeling of limitless dynamic range (power) with absolutely no strain.
The 701's have a rep for being ineficient and hard to drive. The 337 controls
the 701's with effortless ease.

No congestion or compression in the big fortes, no sense of strain.

Stravinsky puts big demands on an amps dynamic range sometimes going from ppp to fff instantly. This makes makes you feel like your in a great hall in terms of dynamics and getting the rythmic articulation right.

[Skylab]

Again, I personally think the 337 is a SIGNIFICANT step above the 336i. Soundstage, bass, transparency - lots of ways. The 336i is a very good amp. The 337 is a world-class amp.

[tomjtx]

Originally Posted by Skylab

Again, I personally think the 337 is a SIGNIFICANT step above the 336i. Soundstage, bass, transparency - lots of ways. The 336i is a very good amp. The 337 is a world-class amp.

X 10

The 337 is world class.
I can't comment on the 336i or 332 because I haven't heard them, but I trust skylab's opinion on that.

I have watt/Puppy's and a balanced Rowland amp in my speaker based system.
I have had many mega buck tube and ss amps here on loan.

I have a close friend who is a hi end dealer who loans me mega buck stuff all the time ( I get to do the burn in.)

The 337 is as good as any amp I have ever had in my speaker system, and that includes some 20,000+ speaker amps.

I didn't want to say this so soon after getting the 337 , 1st impressions and all, but this is one amazing amp that has me listening more to my 701's than my Watt/Puppy's.

I don't think I will change that opinion.

Now all we need is one of those famous Skylab reviews of this amp.

So, how about it Sky, come on, we are waiting :-)

[Gradofan2]

That sounds better... I was thinking the DV337 should be much better... but, I wasn't hearing that on the other thread.

Maybe... I'll still try one.

[jonoliew]

Originally Posted by nick20

That "guy" is Mazuki, and is the same person here...



To say the least, since I know you're interested, at least you'd be able to sell it here for a minimal loss, if you felt it wasn't worth it...


I trust Rob's experience and knowledge. I would however, like to try the 337 against a Bada PH-12 [aka "giant killer"](both amps in house).

+1 on that. I too want to find out which one is better. Cause i have to buy one soon, or 3 lol. seriously.

[Mazuki]

OK... you guys say its great!

On the other thread... they're saying its only slightly better than the DV336.

So... who's right???

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

[Mazuki]

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.

[jonoliew]

So how? would you say this dv 337 will beat the Bada ph12 and dodge?

[NoPants]

Can we contact the maker of the darkvoice amps directly? I'm probably going to end up purchasing this but I'd be ecstatic if this could be run balanced...sorry the "dual mono" tag just won't get out of my head haha

Also by low impedance I was referring to grados and audio technicas which are around 32 ohms. The k701 is rated at 62 ohms but it runs more like a 250 ohm headphone last time I checked.

[Mazuki]

So how? would you say this dv 337 will beat the Bada ph12 and dodge?

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!

[Mazuki]

Can we contact the maker of the darkvoice amps directly? I'm probably going to end up purchasing this but I'd be ecstatic if this could be run balanced...sorry the "dual mono" tag just won't get out of my head haha

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.

[NoPants]

Damn I guess balanced is just out of my league right now. Has anyone heard this alongside the 332? I'm interested in the 337 mainly but the thing is a damn behemoth.

[Mazuki]

Has anyone heard this alongside the 332? I'm interested in the 337

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.