[daycart1]

I'm glad to see this thread revived because I've just joined Team Zotl! I took Darkcloud's zotl with some Sylvania and RCA vt-231's. I need to get some of the 12at7's. I'll post the results as I hear them.

 

[Hirsch]

Still sticking with the RCA until it maxes out, before trying the next set of tubes. At this point, the HD-600 is really showing its stuff. No more laid back Mr. Nice Headphone. The HD-600 is capable of some very powerful dynamics, and at last the ZOTL is getting them to let go. Still has the Sennheiser smoothness, but with some serious punch behind it.

There is a downside. This is a tubeset for the HD-600. With these tubes, the HP-1 has a warm sound...definitely not an optimum match. If the HP-1 is sounding warm, I'm almost terrified to try the CD3K or the W100

 

[daycart1]

Team Zotl really appreciates your publishing your research. Thanks!

 

[Dusty Chalk]

Quote:

Originally posted by Hirsch I hereby withdraw all of my previously posted reservations about the ZOTL and HD-600. With this set of tubes, they're a beautiful match.

Didn't you previously say that you had cables that were tempering something else? Have you tried different sources and cables, just to make sure?

 

[Hirsch]

Quote:

Originally posted by Dusty Chalk Didn't you previously say that you had cables that were tempering something else? Have you tried different sources and cables, just to make sure?

I used some cables to try and temper the brightness of the W100. I'm using the W100 with the X-Can now, and they aren't needed.

I'm trying to get through a bunch of tubes rather quickly, so I'm short-circuiting a lot of what I would normally do in evaluation. I'd want the tubes in place for at least a couple of weeks before I really felt I had a good handle on them. However, once the sound stabilizes (and the RCA was a good lesson to me in waiting however long it takes for that to happen), I'm putting out quick impressions so that people will hopefully not have to do what I originally did, which was to go through a lot of tubes that really weren't suited for the headphone I was using. I'm also trying to do this in days, rather than months. These are only intended to be starting points, not definitive conclusions. I'm hoping that people realize that these are not definitive reviews, and will experiment and post their own findings.

 

[Hirsch]

In a sense, the RCA realized the goal of what I wanted to do, which was to find a good tube set for the HD-600. For the first time, I'm now completely comfortable in recommending a tube set for ZOTL/HD-600 use. I was expecting this to take various 12AT7/6SN7 combinations...not on the third tube set I tried. Phew. I'm still going to do quick evaluations of some others with the Sylvania 6SN7GT's (note, these are prior to the green label version), for completeness.

Moving onward:

Sylvania Gold brand 6211 (pretty tube from Kevin's private reserve). An interesting contrast to the RCA. This tube moves the ZOTL closer to neutrality. Lots of detail. Bass not quite as strong as the RCA, and the highs are slightly recessed. This is moving closer to the traditional Sennheiser sound...and it's good. Another good point of these tubes is that the HP-1 is now usable again. It's still brighter than I'm used to, but the brightness is within normal limits. I wouldn't recommend the RCA with the HP-1, but I'd be happy using the Sylvania with it.

This raises an interesting dilemma, and I don't really have an answer. The Sylvania Gold brand clearly brings the response of the ZOTL closer to neutral than the RCA did. It has a major advantage in that it allows use of both the HD-600 and the HP-1...but is that good? The RCA brought the tonal balance of the HD-600 very close to that of the HP-1...the problem being that the HP-1 stopped sounding like the HP-1, and moved closer to the W100. Personal preference here: I like the HP-1 sound better than the Sennheiser house sound. So, the RCA is clearly adding coloration, but it's a coloration that synergizes particularly well with the HD-600 IMO. So, the RCA may be superior to the Sylvania in that respect. Using the HP-1's original sound as a reference (or was that colored too? no, it was pretty close in the Melos as well) the RCA comes much closer to optimizing the HD-600. The Sylvania is closer to neutral, but it still leaves the HP-1 slightly bright, and the Sennheiser slightly laid back. My own preference is to pick a system and get it sounding right. So, the rating to me: The RCA strikes out with the HP-1, but hits it out of the park with the HD-600. Continuing the baseball analogy, the Sylvania would be a triple with the HD-600, but would be a close call at second base with the HP-1. I'd rather have one perfect fit than two almosts. So, my own choice of tubes for ZOTL/HD-600 would be the RCA, and I'd plug the HP-1 into another amp (this may in fact be how all of this winds up). I wouldn't fault anyone who liked the Sylvania better than the RCA...this is all about preferences, not absolutes.

The Sylvania Gold Brand is a great tube, and is much better with the Sylvania 6SN7GT's than it was with the Brimar 6SN7GT that I was using when I originally tried them. IMO either this tube or the RCA above will give you a very nice sound out of the ZOTL with the HD-600 (but don't forget those Sylvania 6SN7's...)

more to come...

 

[Hirsch]

One thing that this string of 12AT7's is teaching me is just how important the interaction of the two tubes is. I had long ago settled on the Bugle Boy/Siemens 12AT7, and went on a search for the right 6SN7. Going back to the 12AT7's with the Sylvania 6SN7GT, everything I thought I knew about 12AT7's has changed...for the better. The Bugle Boy/Siemens I started off with is the worst tube for Sennheisers that I've heard with the Sylvania...and is the 12AT7 I'd been using most. Not sure what will be the result when I've gone through all the ones I plan to...

The Siemens ECC81. Another great tube, but competely different sound than anything before. This tube has a very lush midrange, but the highs are dark. Lots of bass. Good but not great detail. With the HD-600, this tube produces a classic Sennheiser sound. Beautiful midrange, laid back highs, and deep and heavy bass. I'd rate this a very nice fit indeed, and a completely different sound than the RCA. The Siemens can handle all of my headphones (even if not always perfect), something none of the others could do. This tube is a perfect fit with the HP-1. Still slightly dark, but it produces a sound that simply pulls you in. Just to see what would happen, I tried the W100 with this...and got the best results I've had with the W100 on the ZOTL to date. The CD3K was interesting. Tonally correct, but the CD3K just didn't have the detail I'm used to with that headphone. So, there's probably some information that's not getting through the dark coloration. Wonderful with the HD-600, a perfect fit for the HP-1, and capable of taming the W100 all in one tube. That's some tube. IMO the absence of the last word in fine detail is the main flaw.

Three 12AT7's in a row that work well with the HD-600. Got a good safety net now.

still going...

 

[Dusty Chalk]

Quote:

Originally posted by Hirsch I'm trying to get through a bunch of tubes rather quickly, so I'm short-circuiting a lot of what I would normally do in evaluation...

Oh.

Never mind.

(Wipes brow.)

I misread that, initially...

PS Even to those of us who do not own a MicroZOTL, this is very interesting. I especially like the way you do not give a simple "this one is better than that one" rating.

A+!

 

[Hirsch]

Time for a quick reminder of what I'm trying to do here. I'm taking a bunch of 12AT7's, getting them warmed up, posting quick impressions, and moving on to the next. This is NOT intended to be a comprehensive evaluation of the tube. That would require trying the tube with different 6SN7's, changing cables, sources, and getting used to the sound in different kinds of music over a period of weeks. Not possible given my own time constraints. So, what I'm doing is posting impressions, using the Sylvania 6SN7GT (I LIKE that tube), trying a couple of different cans, but focussing on the HD-600. The idea is to provide some sort of starting point for others to investigate more deeply, and post their own conclusions, without wasting quite as much time and money as I did on dead ends. To that end, I hope some people are finding this exercise useful.

Mullard 6201 (Kevin's private reserve): A tube very close to the Siemens. I'm picking tubes in more or less random order, so it's almost eerie the way they're starting to group by sound type. I had tried this tube with a Brimar 6SN7 (also from Kevin, but not private reserve-the 6SN7 is one of the tubes that he keeps the best in his "cookie jar" to support his hardware customers), and ignored it as warm and undistinguished. I'm glad to be able to reverse myself, and say that this is also a very nice tube. What a difference a 6SN7 makes! The Mullard is very close in character to the Siemens, but is moving toward neutrality...dark coloration, but not as pronounced. Very nice to listen to on the HD-600. Dark, the last word in detail not quite there, very nice through the midrange, and lots of bass. This tubes fits wonderfully with the HP-1. Completely natural sound, everything in place. Hard to evaluate because you lose yourself in the music, and forget to listen to equipment characteristics...this one lets the HP-1 extend itself wonderfully. This is as good a tube combination as I've heard for the HP-1. The CD3K brings it back to reality though. There is a small absence of detail. In a lot of ways the CD3K is like a microscope-if there's any detail missing, the effect is highly magnified. The missing detail is completely unnoticeable on the HP-1. Hmmmm....going to think about that one.

Another good tube, in the same vein as the Siemens, dark and missing just a tad of detail, with the coloration less obvious than it was on the Siemens.

lots more to come...

 

[Hirsch]

dcg visited today, and we rolled some tubes in the ZOTL. We found a later version of the Sylvania 6SN7GT than I've been using that may be a better tube. I'm going to keep my 6SN7's the same until this walk through the 12AT7's is done, so dcg may get a handle on the JAN-CHS-6SN7GT before I do (he now has a pair). If so, I hope he'll post his findings. We also found this little tube:

GE 5965 Cleartop, side getter: GE sometimes doesn't get the respect it deserves. The GE 6SN7GTA is one of the better 6SN7's around. And if you look at Tung Sol tubes, guess who made most of them, even if Tung Sol's got the name recognition. The GE 5965 is a pleasant reminder of how good GE can be...and some problems as well. Of the four we tried, three were microphonic, one to the point of unusability. Still we managed to get a workable pair out of it. After letting them warm up a bit, I did some listening this evening. This is a very clean tube with the HD-600. Very full, clear and defined bass, good definition, extended highs. I'm going to use the word "clean" again, because if I had to describe this tube in one word, that would be it. It gets out of the way and lets the headphone play music. A fine little discovery, if you can find a non-microphonic pair. With the HP-1, a different story. The first question that came to mind was "where's the bass?". Bass response was gone...almost as though a high pass filter at about 150 Hz was in place. The rest sounded nice, but there was little or no bottom. Not good. With the CD3K, same thing. This tube seems to have a problem with bass response into low impedance cans.

A good tube for the HD-600, but beware with low impedance cans.

more to come...

 

[dcg]

Quote:

Originally posted by Hirsch If so, I hope he'll post his findings.

Yes, well, as soon as I get the proper tool to open the damn thing up. The hardware store was closed on the way home.

 

[daycart1]

Yes, rest assured that Team Zotl is taking careful notes; thanks again.

I think I now have the measure of the stock tubes, so I'm ready to start with the RCA blackplate shorties (vt-231?) and the Sylvania 6sn7gt (rats, just noticed the GREEN lettering...) Tomorrow I hope.

Then I'll try to get some 12AT7s.

ARe 6201 safe for Zotl generally or should one stick with 6211?

Hirsch, is it OK generally to use tubes listed as substitutes on "Duncan's tdsl" even if they have "different ratings or performance"?

Thanks.

 

[Hirsch]

Quote:

Originally posted by daycart1 I think I now have the measure of the stock tubes, so I'm ready to start with the RCA blackplate shorties (vt-231?) and the Sylvania 6sn7gt (rats, just noticed the GREEN lettering...) Tomorrow I hope. ARe 6201 safe for Zotl generally or should one stick with 6211? Hirsch, is it OK generally to use tubes listed as substitutes on "Duncan's tdsl" even if they have "different ratings or performance"?

Don't underestimate those Sylvania's with the green lettering. They're a very nice tube, particularly if they have the bottom gettering. The brief listen we had today left me wanting more...and those are the tubes I want to try when I get through the 12AT7's. I've got the white lettered ones also (and have been using them), but those green lettered ones have a lot of promise (besides, I've got a bunch of them...got lucky at some auctions

)

I've used 6201's with no problems. I don't have a really technical orientation, so I'm hoping that someone who does will answer your question on subtitutes on "Duncan's tdsl".

 

[Hirsch]

I'm starting to feel like the Energizer Bunny, with a ZOTL in one hand and a 12AT7 in the other. Still going...

I was going to start my post on this tube with saying it was boring and uninspiring. At that point I remembered that I had bought these before I had a tube tester. So, I checked them out, and indeed, one of the tubes had a dying section. Luckily, I had a spare, so these notes are from a pair that tests near perfect.

Telefunken ECC81: Diamond on bottom, but a number in the diamond. Was this made by Telefunken, or OEM by Siemens? I have no idea. In any event, this tube is boring and uninspiring. Sad when replacing a dying tube with a perfect one doesn't do anything for the sound. It's not that this tube does anything particularly bad. Detail is excellent. Bass is good, high end extension is good, midrange is good. Tonal balance slightly warm, but that's actually good with the HD-600. All in all, the whole is less than the sum of the parts. It felt like I was listening to a musician on an off night. The PRAT wasn't there. Perhaps is was the dynamics, which may have been restricted. I felt the same way using the HP-1 and the CD3K. Everything necessary for a good musical experience was there, but I couldn't wait to turn the thing off. Maybe another 6SN7 would help, but that's outside the scope of these brief impressions.

An important note, particularly since I'm panning this tube. Tubes perform differently in different amps, and with different companion tubes. Anything I write in these summaries is specific to the Sylvania 6SN7GT and the ZOTL. You may try this tube in another system and think it's perfect. Further, this is my opinion only. You might replicate my system exactly, and still think this tube is great. All I can say is that I didn't. Blech.

more to come, but the Outlaw 950 is due here tomorrow, and there may be an interruption in the flow of 12AT7 impressions. I also think I'm getting close to the end of the ones I want to post about. Besides, I'm starting to get curious about which of my 6DJ8/6922 pairs is the best one for the SHA-1...

 

[Hirsch]

And another one:

Amperex Bugle Boy (France): Amperex had factories in Holland and the US. Why one says "made in France" is beyond me. Still, here it is... This tube shows why warmup is so important. At three hours in, this tube had a dark sound, very similar to the Siemens in some ways. Five hours after that, it's a different tube. With the HD-600, very clean and detailed, slightly to the bright side of neutral. Good dynamics. Got me interested in the music, and wiped the Telefunkens out of my mind. Good bass extension, and tight definition (was looser earlier in warmup). A good word to describe this tube is seductive. I kept trying to listen to the sound, so I could write one of these brief summaries, but lost track of what I was doing because the music took over. With the HP-1, the brightness is more pronounced, but still a good listen. The CD3K sounded brighter still, with a hot high end. This bothered me at first, but actually became less important the longer I listened. I just kept falling into the music. The distinguishing character of this tube is not any single aspect of its sound, but rather its almost hypnotic seductiveness. At its best with the HD-600, but very good with the HP-1, and almost as good with the CD3K.

This tube is a contender to be the pair that stays in the amp when this survey is done, and I screw the cover of the ZOTL shut again.