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Singlepower tube rolling thread

post #1 of 334
Thread Starter 
You knew this was coming, didn't you?

I'm going to post a couple of fast impressions of some tubes, and fill in gaps as time goes by. I'm hoping that others will also report tube-rolling experiments, so we can build a database of what tubes work best with Mikhail's amps.

I also want to point out that tube construction changed over time. If you don't have NOS tubes with dates on the box, it becomes important to look at the tubes really hard. Find matching date codes if you can. There are some small differences in construction from year to year that do affect the sound of the tube. If you've got a mismatched set, the sound won't be as coherent as it should. IMO it's more important that the tubes be the same construction than that they be matched electrically. IME the Supra sounds better with slightly mismatched tubes that are identical than with electrically matched tubes that may be from different years.

OK, I'll start with the standard. Sylvania VT-231, 1940's production. Also known as Sylvania 6SN7GT, or JAN-CHS-6SN7GT. If they were made at the same time, they're all the same tube, regardless of label. And they all sound good. However, there was a change in contruction around 1953 or so, and tubes made before that are considered more desireable. If this is the only tube you've heard in one of Mikhail's amps, it may be all that you will ever need. A good set has the complete package. Good high end extension, a warm and full midrange and decent bass extension. Imaging is precise and the perceived staging is wide. What could be better?

JAN-CKR-6SN7GT aka Ken-Rad VT-231. Clear or dark glass doesn't matter, but it must be the staggered plate version. Here's where it gets weird. I didn't like this tube early on. I thought it had a hard area in the midrange that gave the Sylvania a clear edge. I was wrong, I think. I've now tried two sets in the past week, and there's no trace of the hardness I heard before. My suspicion is that the amp had not fully burned in when I tried them, and that what I was hearing wasn't the tubes, but the amp itself. It's also possible that it was a cabling or source issue, since there have been a lot of system changes since the early tuberolling attempts. Right now, these tubes are heaven. Extended highs, a crystal clear midrange lacking some of the Sylvania's warmth, and an extended bass response. Interesting, actually, since these were also the tubes I eventually settled on with the MicroZOTL when I had one. They've got something that eventually brings me back to them. The level of detail seems higher than it is with Sylvania's, and the bass impact of these tubes really comes through on the R10.

So, at least for these two tubes, I'd go with the Sylvania if midrange warmth is critical, and with the Ken-Rads for a more balanced presentation. I'm a big fan of balance, and right now the Ken-Rads seem to be hitting the spot. But I'd always have a set of the Sylvania's nearby...

more to come...
post #2 of 334
I dont have my MPX3 yet, but I'd like to be a part of this when I do get mine (4-5 weeks...). What are some requirements for tube rolling to ensure quality? More specifically, should I try to get 3 matched tubes? Or 2 matched + 1 is good enough? I guess I just want to know whether it's necessary to grab 3 matched or 2 matched + one in good condition.
post #3 of 334
Hirsch,

If you have a Sylvania 6SN7W (or A) metal base lying around try it in the driver position. It sounds fantastic with the VT-231's. I haven't tried my Ken-Rads yet, I guess I'm gonna have to find 'em...

gb
post #4 of 334
Habib,you only need to get a matched pair,the driver tube on the far right does not need to be matched and can be from a different manufacturer.
post #5 of 334
Thread Starter 
Quote:
Originally posted by gbeard
Hirsch,

If you have a Sylvania 6SN7W (or A) metal base lying around try it in the driver position. It sounds fantastic with the VT-231's. I haven't tried my Ken-Rads yet, I guess I'm gonna have to find 'em...

gb
I have indeed been using a 6SN7A in the driver position with the VT-231's lately, but was going to report on that in a later post. One of those went on Ebay this morning at $107 for a single tube
post #6 of 334
Here are the tubes i've liked the best so far in my Singlepower amp.
Sylvania Vt-231
KenRad VT-231
I like both these tubes used one with two of the others alot. I like the straight set of Sylvanias the best so far, but have been using the one KenRad with two sylvanias for the past week and have had no desire to switch back yet. I've also got a set of 1954 Hytrons that if I never heard the other tubes would have been great. But they don't do it for me compared to the Slyvanias or the KenRads. I've built up a stash of three sets of the Sylvanias so now I can try some of the other Sylvanias or something else I learn about on this thread.
post #7 of 334
Sylvania VT-231.

Stop. Do not pass Go.
post #8 of 334
LOL, yeah, what FCJ said

Hirsch, my apologies, but due to you & Bozebutton's pointing me to those WWII Sylvania's, I won't be contributing to your database...

I'm hearing what I want to hear, those tubes aren't coming out of my MPX3 till they expire... and then I've got spares

I would love to hear the Ken-Rad's though... who knows, maybe I'll pick up a set...

Thank you for all your help regarding tube selection, I couldn't put into words the pleasure, the fun and the connection to the music I've enjoyed courtesy of these tubes and this amp... Simply blows me away. Thanks for introducing us to Mikhail too...
post #9 of 334
Quote:
Thank you for all your help regarding tube selection, I couldn't put into words the pleasure, the fun and the connection to the music I've enjoyed courtesy of these tubes and this amp... Simply blows me away. Thanks for introducing us to Mikhail too...
Amen to that, HighwayStar! Hirsch's amazingly detailed and well articulated review of the Supra (followed by Tom's commnets concerning his SDS) led me down the same path. Mikhail has done fantastic work with my SDS which mates exceptionally well with absolutely any phones I've thrown at it, especially the R10s and HP-2s. I would have never believed that headphone listening could be this blissful!

Tube-wise, using a full set of the Sylvania V-231's has also been my favorites combo so far. I've also got 3 Russian-made Electro Harmonix 6SN7EH tubes that I need to give a try and report back on here.

There is a single 6SN7GT tube that Mikhail threw in that is a GE 6SC7 box (so I'm a bit confused). The tube itself is labelled as JAN CHS 6SN7GT (Sylvania) variety so I'm not sure of it's origin, but I'll try it in the driver stage.
post #10 of 334
Hey Hirsch:

This is going to be an interesting thread. So I'm checking in—so far, I have tried New Stock Sovteks, Electro Harmonix, and NOS CBS Hytrons in my MPX3. First off, forget about the Sovtek 6NS7's as they sound really lousy. I was at the electronics store for something else and they just happened to have a stock of them for 5.00 each and thought I'd give them a try. The sound was flaccid and weak compared to any of the others. Weak Bass and very little HF air. Tried one of these as the driver in combination with the others and their sound was diminished.
The Electo Harmonix were the most dynamic in the MPX3 . The Bass is also the best and biggest of the three; quite detailed and tight. Midrange is also full of detail air and transparency up and down the range. Gets a little too bright in my system at times, but generally the most fun and involving tubes to listen to so far for me.
The Hytrons are the most mellow and have the most refined sound. Very smooth and airy up and down with a nicely detailed high end. Not much punch. Never gets bright. Bass is there, but not very detailed and tubby sounding.
I have settled on using an EH for the driver and the Hytrons as the outputs as the EH seems to still have the greatest influence over the overall sound; but the Hytrons seem to keep the EH's from going over the top. This combo yields a sound that is involving with asmoother mid and highs than the EH's. Good Bass, but not as good as with 3 EH's. Fun level down one notch and refinement up one. Wondering now about VT-231's. Anyone have an extra set?

Regards,
Bob
post #11 of 334
Quote:
Originally posted by HighwayStar
Thank you for all your help regarding tube selection, I couldn't put into words the pleasure, the fun and the connection to the music I've enjoyed courtesy of these tubes and this amp... Simply blows me away. Thanks for introducing us to Mikhail too...
Couldn't have said it better myself. . . .
post #12 of 334
bobjew, You can check out www.tubeseller.com he has sylvanias most of the time, also the KenRad's.
post #13 of 334
Thread Starter 
The tube combinations are where it's going to get interesting. I had tried the RCA VT-231, and thought the high end didn't cut it compared to Sylvania's. However, I heard CD44hi's MPX3 with a Ken-Rad in front of RCA's, and it was a different story. Nicely balanced sound. The key tube does indeed appear to be the driver (right hand tube). I've been able to get away with a lot as long as I keep a good tube there.

I like the 6SN7A metal base as the gain tube a lot. It seems to add a bit of texture and really maxes out the detail of the amp. The downside is that the sound gets a bit dark. The tube I have is fairly low Gm, and dynamics seem to suffer a small amount.

Another interesting tube is a weird Sylvania 6SN7GT from 1950-52. Unlike most bottom-gettered Sylvania's of the time, it doesn't have the T-plates. It uses slightly staggered flat plates, looking very similar to an RCA tube. There are both black and gray plate versions. The gray plates are very dynamic, and throw a huge image, but ultimately I found them fatiguing. The black plates sound nothing like the gray plates, and are very close to the VT-231, IMO. These tubes transmit an enormous amount of detail. I had initially thought that they might be slightly dark, but am not sure anymore. I've done a much more careful job of date matching, and switching tubes around until I've got the right tube in the gain position (the only way I know how to do this is to use my test results as a first attempt, then just move them around and listen until it's right). I still don't have the full measure of these tubes, but they are a lot of fun to listen to.
post #14 of 334
Thanks, Tom, just being lazy.
post #15 of 334
The more I listen to the one KenRad VT-231 in the right socket and the center, left with the Sylvania's the more I like it. I think this combo makes the HP-2's sound really great. I like the CD-3000 better than the HP-2 with the straight Sylvanias.
Anyone tried Mullard's or Raytheon's?
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