hello Mc5baby,great thread!Im looking forward to reading responses from Supratek owners,,,
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Not the conversation you wanted, but you might just focus on member bwhite's posts in the 'preamp deal of the century' thread. If I recall correctly bwhite was one of the eariler tube rollers and power cord rollers for the supratek preamps. I bet he's covered this topic in detail. And with regards to that thread, I can imagine any Supratek owner not printing out that thread and at least skimming through it (if not reading it completely!). Sure there is a wealth of knownledge about the supratek to be gained from there. You should be so fortunate.
Here's mine (Chenin):
Rectifier - Mullard GZ34
Regulators - Sylvania 6F6G's
Phono = Mullard M8080 and Tele 6922 CCa
Linestage - RCA VT231 Gray Glass
I can also recommend the ff. with gusto for the linestage tubes
1. Tungsol VT231 Black Glass
2. Raytheon VT-231 Black Base
3. Sylvania 6SN7W short Bottle
4. Sylvania 6SN7GT VT-231
Thanks Aroc! Also... Ecclectique & Fiddler have added a great deal of tube info too. Actually... LOTS of people have added great tube info to that thread. It's so rich with good information.
In my Cortese, I use:
Regulator: Western Electric 350B
Rectifier: Bendix 6106
Line: Mullard CV181 / ECC32 (kinda like a 6SN7 but doesn't always work in Syrah pre's - not the very best sounding tube, but quite close. I use mostly because it is awesome looking! :) Similar sound to the Tung Sol Round Plate...
Phono: Mullard E180F - Telefunken CCa
Best 6SN7 Tubes:
Tung Sol Round Plate (6SN7GT/VT231)
Ken Rad Black Glass *note three different sound types
> Marked NAVY - these are the most open sounding
> Marked VT231 - These are the most "neutral"
> Marked 6SN7GT (no other markings) these are "dark"
* in general the Black Glass Ken Rad is the most romantic, richest sounding tube in this preamp. The three "grades" mentioned above are all within the romantic spectrum.
Sylvania 6SN7W Metal Base
No doubt the best rectifier is a WELL BROKEN IN Bendix 6106. This rectifer sounds terrible when new - weird. I don't know how long it takes to start sounding good but I am guessing many. Be patient, it will get good. For those who had tried and gave up, keep on trying. Let that sucker bake! To break in, I disconnected my line stage from the power supply - plugged in some cheap regulator tubes and let the powersupply run.. day and night for a week or more.
The Mullard rectifiers (GZ34, GZ37, GZ33, GZ32) are popular but warmer, less impact, more muddy sounding tubes (sorry).
Various 5V4G tubes produce a broad range of neat sounds. Fun to try because most are cheap.
350B is the best - hands down.
6F6G is reported to be good (i've never used)
Sylvania 5932 (three types)
> Dual Black Plate - nice sounding tubes
> Gray Plate with holes
> Gray Plate no holes (super neutral sounding to the point of boredom but man.. these make the preamp sound tonally accurate)
KT66 MO Valve (GEC,Genalex,etc) Nice sweet sound.. Involving but these have to be used with a Mullard rectifier.
Tung Sol 5881 a good starter tube but you will quickly outgrow it.
great comprehensive post !
Is Bendix 6106 better then Philips Miniwatt GZ34 (which I'm using) for Chenin ?
For short time I had WE350B I had impression that sound was too worm, I have warm monoblocks, so what is the best way to have a little more highs (what tubes) without sacrificing anything.
I'm using Ken Rad Black Glass VT231,Philips Miniwatt GZ34 (rest is stock).
Sorlowski - give the Bendix a try. It is a somewhat inexpensive tube too.
The WE350B's are not exactly warm on their own but when paired with the GZ tubes, they can be...
The Early(1950's) RCA 5V4G (ST Shaped - black base) tubes are a more open sounding rectifiers. I think these are available NOS for under 35 bucks.
I think the GZ34's (as well as most other Mullard GZ tubes) are too muddy sounding. While the Metal base GZ34 is one of the best rectifier choices it pales in comparison to the Bendix.
Now.. when I first got the Bendix, I hated it. It did something strange to the pace of the music - everything seemed awkward. I think others who tried the Bendix at about that time had similar experiences. Once I burned in the Bendix though, everything came into focus. The Bendix is on the warmer side of neutral but the bass is tight, detail is there, the dimensionality increases substantially. Pace is correct. Its a great tube.
Like I said above. Burn in the Bendix. Just disconnect the power supply from the line stage, insert the Bendix and let it cook for a week or more. Every day or so, give it a listen and eventually it will outperform anything else and stop sounding weird.
Another good thing about the Bendix is that it's a slow starting tube and does not stress out the other tubes when it heats up. Some of the Mullard GZ's start fast and in some cases blow fuses on Supratek's. This stresses out the other tubes and shortens their lifespan.
The Ken Rads are good tubes - very organic -rich and warm. Changing these with Raytheon VT231 or Tung Sol Rounds will add more transparency & detail but you will lose some of the midrange magic, weight and round-ness you like with the Ken Rads.
Another possibility is the RCA 5692 red base tubes. I really wanted to like these tubes because they do many things well but for my system I felt they were too detailed and I personaly loved the warmth of the Ken Rads / sweetness of the Tung Sols. If the rest of your system is warm sounding, the 5692's might work for you. Great bass, good detail and dimensionality.. just not "luxurious" or romantic.
Amazing, this is exactly what I was hoping would happen. Looks like we can all get into bidding wars on ebay now. I just stopped in to check this and will be reading more closely later, when by the way I will be listen to my new Chenin! I gotta go pick it up at the hold center a ways away cuz I got drunk and slept on a friends sofa last night, obviously missing the Fedex guy, damn.
I'll have a few more questions too, I'll get to those later.
But the Bendix does not work for the Chenin, only for the Syrah! There is a small change in the PSU according to Mick. It was mentioned to me a year ago when I ordered my unit. I think this was covered on the other thread as well. I still have the tube. I bought it new and tested NOS but it is the only rectifier that I tried (from the many recommended at the other thread) that produces a "chugging" sound no matter what source is selected or what tube combinatons are employed on the other circuits.
I hope someone can confirm my experienced as well.
Amandarae - that's a bummer! I wonder what changed in the Chenin power supply that makes the Bendix 6106 not work. Well.. the people with Cortese's are lucky.. you can use the Bendix 6106 and the Mullard CV181's Two great tubes which do not seem to work in the other Supratek's. Actually maybe the CV181's work in the Chenin - I know they do not work in the Syrah.
I am getting my Sauvignon next week! Hooray!
On a kinda swap basis for some vinyl stuff, Mick is sending me some NOS tubes he likes to run in the Sauvignon. I'll know what they are when they get here and WILL report back.
As a real newbie when it comes to tube rolling, I see that some good trading goes on at Ebay, but what are the best sources for tubes?
Has anyone tried any JJ tubes in Sauvignon's? A friend of mine imports them to Aus.....so could be worth a try...??
Thank for interesting reply, are you sure that Bendix would work with new Chenin ? (some people claims it did not).
Any Bendix would do, or it have to be "Bendix 6106 Red Bank" ? I'm real rooky when it comes to tubes, but really like them.
I have got usual Philips MiniWatt GZ34 not metal base, is there big difference between those two ?
You might even want to think in terms of 300 hours for full break-in plus your opportunity to really come to understand the sound with broken in tubes.
I would also suggest only making one tube change at a time. This makes it a long process since you will have the break-in to go through with each set of tubes (assuming that they are new or NOS), but it is well worth it.
I'm surprised you can hear differences in Ken Rad 6SN7 of different prints. I've literally handled over 500 of these tubes in my lifetime and can't discern any differences. I'm also surprised you prefer their midrange to Tung Sols. I have always found the KR midrange subpar for a 6SN7.
As for my Supratek (line stage only):
6SN7: I use primarily Tung Sol round plates, although I do swap in Sylvania 6SN7Ws, Raytheon (flat plates), Sylvania VT-231 (also 52 Bad Boys), and RCA grey glass on occassion. I'd skip the CV181/ECC32 if I were you. It's one of those "midrange" only tubes with anemic bass and attenuated highs. Fact is, it was never designed for audio purposes (it's an oscillator tube).
regulator: Visseaux 6L6G or Mullard EL37. While I like what the 350B does for the midrange, they aren't my cup of tea for the rest of the audio spectrum. 6F6 tubes are too lean (and a bit edgy) for my tastes and my system. KT66 didn't float my boat either (bass was subpar, soundstage was collasped).
rectifier: Philips metal base GZ34. Defintely not muddy sounding, and far more open then the later production black base Mullards (which I agree are more lush and syrupy). I've never tried 6106/5Y3 in this position, but I'll give it a shot this weekend. I'm surprised it works well in a circuit designed for GZ34.
Disclaimer: this is all, of course, personal opinion based on my system only. For full disclosure, I should also state that I was (and still kind of am) a tube seller.
Bwhite, you are a genius.
I tried the 6106 months ago and I think I was the first to slam the tube for having weird timing. Didn't like it at all.
I took your advice and let it burn in for three days. Wham! This tube rocks. Clearly better than the venerable 5AR4/GZ34. No contest. I didn't realize the 5AR4 was muddy until I put the 6106 in. And the 3D palpability is much increased.
Once again, thanks for the inspiration to give this tube another try. It's now my reference rectifier.
Whoopadeedoo - as a tube dealer, I am surprised you don't know that especially with military spec tubes, printing means something. And yes. There are three distinct "flavors" of Ken Rad Black Glass tubes. In vintage non-military spec tubes, parts & materials can vary tremendously. Differences in tubes are audible even by month of manufacturer in some cases.
What kind of a Supratek do you have?
Whoopadeedoo - Are your Visseaux 6L6G's the ST glass or tall skinny glass? I got quite a few of the latter but I've only seen picturers of the former. I rolled them in my Sauvignon a long time ago. I used Sylvania 5932 dual plate for about 18 months. First in the Sauvignon and then in the Cabernet. It is IMO a real sleeper as regulator. I think the unique dual plate structure is what sets it apart. It gave me a rock-solid soundstage with neutral freq
response. Regulator tubes are a different lot when it comes to judging sound. Some of the regulator substitutes have an unusually high heater current and will place a larger demand on the power supply and also affect the current draw through the rectifier hence the voltage sag on the recifier and ultimately the operating point on the signal tubes. I wonder sometimes if that load is adversely affecting the expression of the music or maybe it's just getting everything in its sweet spot.
Sylvania VT-231 has excellent top-end extension, tight bass but could be lean for some tastes. Sylvania 6SN7GT 1952 tall boys are very similar to Sylvania VT-231 but with a bass boost below 100hz. RCA grey glass have maybe the best midrange of all 6SN7GT's with very nice harmonics.
I have both the carbon coated ST Visseaux and the tall GT glass version. I prefer the GTs by a small margin. If you want to sell any of your GT Visseaux, I'd love to buy them :-)
Tung Sol round plates stays in my 6SN7 position the vast majority of the time. However, I love the RCA grey glass midrange when I'm looking for something a bit more romantic and full. I'll swap in the Sylvania VT-231 or Bad Boys if I want more air.
You've arrived at the erroneous conclusion that base prints mean something. They don't. It was not uncommon for base prints to be labelled months after the actual date of production, sometimes completely removed from the actual site of production (e.g. at distribution centers, where a lot of rebranding occurred). With the two notable exceptions of 5692 and W/WGT-suffixed tubes, there was no such thing as as a military-designed 6SN7 .... only different base prints for military-designATED 6SN7 (the US military used VT-231 as its numbering system, the British used CV1988, etc.). Yes, these tubes had to be made to milspec standards, but no, they weren't any different then their commercial-bound counterparts. There wasn't a factory churning out just military-designated tubes. Factories distributed the same exact tubes with different prints based on its intended destination. A Tung Sol 6SN7GT in commercial red and blue boxes is the exact same tube as a Tung Sol VT-231 in tan military boxes.
What are the three "flavors" of Ken Rad black glass you speak of? I've removed the glass from about half a dozen Ken Rads with various base prints (fwiw: I'd be happy to post pics of the internal constructions of some 6SN7s). Perhaps you've stumbled across some insight I overlooked. The only differences I've found is minor mica variations and grid posts constructed of different materials.
It's logical fallacy to assume that the differences you hear in tubes is due to vintage or material differences. Each and every 40s tube was hand-assembled by both skilled and not-so-skilled laymen. Thus, they're subject to variations due to build quality alone. Chances are, any differneces you heard were quality control related more then anything else.
To clarify, I am not doubting you hear differences. Some people simply have better auditory acuity. But you are the first person I know who can hear marked differences in Ken Rad black glass 6SN7/VT-231.
I currently use a Chardonnay.
Whoopadeedoo. The differences in sound are dramatic. I am not the only person who has heard the differences. If you have a the three sets (6SN7, VT-231, and NAVY versions) give each a listen and if you cannot hear a difference, I'd be quite surprised. It doesn't take any particular or special "auditory acuity" to hear.
I didn't want to get into it but your descriptions and sonic impressions of the other tubes (350B, 6F6G, KT66, Metal Base GZ34 and particularly the CV181) leave me puzzled too.
Here it is http://www.tubeseller.com/index.html
Shoot Mr. Malecki (Bob) an e-mail and if he finds a pair, he will contact you right away. All tubes he sells are tested and has a 30 day warranty (see homepage). I bought tubes from him and if he states "NOS", it is really NOS unlike the Ebay stuff. An honest professional guy in my experience and I can truly recommend his services.
How many of each "type" of KR have you auditioned? How can you rule out it wasn't a build quality issue due to a small sampling size? I've handled over a hundred of each type (just sold about 30 pairs of the Navy type in the last half year) and they sound the same to me as the other prints.
Tell us how you feel about the 350B, 6F6, KT66, Metal Base GZ34 and CV181/ECC32. I think everyone would benefit from unique opinions.
The Tung Sol round plate is something special in all my applications (I have five gear that uses 6SN7s: Supratek, Audio Note, Korneff, Cary, and a Wheatfield headamp). It's always very open and smooth, with good linearity from top to bottom (no particular spectral emphasis unlike, for example, Ken Rads that emphasis bass). The Sylvania VT-231 are a bit more airy in the treble, but it lacks bass performance compared to the Tung Sol. The Syl VT-231 mids are also not quite as solid, although some might prefer its more delicate presentation. The RCA grey glass is a lot more euphonic and full sounding compared to the Tung Sol. RCA always romantizes the music in my systems, and I love it for that specific reason.
I got the Bendix 6106 in the Cabernet. It is more than a little tipped-up. The bass is even less than that of the Sylvania Vt-231 with a gz34 or gz33 rectifier. And I have the Sylvania 6SN7GT 1952 tall-boys, which are well known for their bass, in the preamp right now.
For example, when playing "poco a poco" performed by fourplay the drums are normally featured prominantly and there is a tension in the music between the bass section and the melody. With the 6106 the bass and drums become an accompanyment to the melody.
What bass is present is at least well controlled but that has never been a problem in my system. I seem to have lost some pitch resolution in the bass also. For the rest of the audio spectrum the detail and resolution is very good, even excellent. There is a slight incoherence in the soundstage depth. Mainly due to the reduced bass output.
So does the bass ever get bigger with the 6106 as it breaks in?
I just measured my system with Tact RCS. This is in-room response and no my room is not an anocheic chamber. Previous rectifier was a gz33. The current rectifier is a bendix 6106. Output below 300hz is reduced by a few db. There is a hump in response from 3-5khz by at least 2-3db. From about 8khz on up it just climbs a mountain. I am up at least 5-6db at 20khz. I can't consciously hear anything about 17khz but somehow I can percieve a 20khz test tone.
Interesting Jazzdude, I also run the Sylvania 6SN7GT 1952 "bass kings" in my Chardonnay and I have noticed no drop in bass performance with the 6106s. Actually, to the contrary. The bass quantity hasn't increased with the 6106s over the 5AR4/GZ34s, but the bass quality has improved. The bass seems tighter and more focused. Actually, everything is more focused. There was always a very slight fuzz that I couldn't find, but with the 6106 the notes are very crisp and clean. No more fuzz.
When I first plugged the 6106s in months ago, I hated it. But with burn-in, it really transformed. Unlike the GZ33 & GZ37 which remained total dogs.
Mick gave me a GZ32 to try, but it pop and crackled from day one so I took it out immediately.
Jazzdude, a quick question. Have you compared the Tung Sol Round Plates to the '52 Sylvanias? If so, I would be really interested in your opinion of the two. I may try a pair of Tung Sols, but I am thrilled with the '52s.
Fiddler - I'll give the 6106 a week at 24/7 and see how it does. The actual articulation of the notes from start to finish is fine and this is the most important thing. There is no question that it is a very good rectifier, but at this point it hasn't destroyed the competition.
I have a dual-getter metal-base amperex bugle-boy gz34 that goes in after the 6106
The cabernet only uses a single triode out of the dual-triode 6SN7GT. The other triode used is the we101d. Which might explain a difference in bass output between my preamp and yours.
I might give the tungs-sol round-plates a place in the hot socket one day. But for now I am working on finding the best rectifier and regulator. I am trying some alternative regulator tubes including the 6f6g and we'll see how it goes. One thing I can already say based upon my experiences. That is that the higher plate dissipation of the regulator will increase the operating point on the rectifier causing the signal tubes to distort more. So for the cleanest and most natural sound and highest resolution the 6f6g is going to smoke the 7581, 5881, el-37, kt-66, el-34, 6l6gc etc. And I am not really concerned with freq response for my system although I will note it. What I am after is the best execution of the note from start to finish and including the harmonics. I want maximum resolution of the music and for the preamp to still perform without a hint of strain.
Hi Whoopadeedoo - I really don't want to argue about it so... I'll take your word for it, printing means nothing, the construction is the same, and they all sound the same and we'll leave it at that.
How many KR's have I owned? I don't remember exactly but I have owned many. As I am sure you know, the ratio of good "pre-amp" quality 6SN7's (low microphonics / quiet) to not-so-good is relatively slim. Depending on the tube manufacturer/type/vintage, its often very difficult to find a nice vintage 6SN7 which is adequate for use in a line stage...Particularly the Supratek which is quite sensitive to tube quality. Having said that, for several years, I purchased numerous KR Black Glass tubes from various sources and maybe, at best, 1 in 10 tubes were quiet enough (no squeeks, no microphonics, no crackle) to even be considered as usable. Of the KR tubes I purchased during that time span, I kept about 20 (10 pair).
Also during that time, I was cycling through various amplifiers, cables and digital components. I discovered that I could "tune" my system with the various "flavors" of the KR black glass tubes. Initiallly I didn't know they were sonically different but after swaping back and forth tubes and matching with various components, I soon realized that they were all similar but very different. Certain marked Ken Rads were totally unusable with certain component combinations while other KR's were seemingly perfect.
Using the KR's in a line stage preamp produces a much different effect than in an amplifier. So for those people who use these tubes in amps and hope to obtain various sonic results, I don't know what to say because I would expect the results to be much more subtle and possibly less noticable in that application. It is when the tubes are used in a line stage - particularly the Supratek - that the difference in sound is obvious.
The 6SN7GT marked Ken Rads are noticably dark, and rolled off. The VT231 marked tubes are the most even/neutral of the bunch, the NAVY tubes are far more extended in the highs than the other types...but still maintain the KR signature.
Well.. your descriptions of the other tubes when used in a Supratek are weird, particularly the CV181 description. I know that CV181's do not work in Chardonnay and Syrah preamps (for whatever reason).
The "midrange" on a 350B is more-or-less quite neutral. In fact, the 350B is oddly one of the least "involving" or romantic sounding tubes available when used as a regulator in the Supratek. Where it stands out and what makes it the best, is what seems to be the most brute force and blatant accuracy of all regulator tubes. Which may be why they do not float your boat -as you put it. You state you like what they did to the midrange and that makes me a bit curious as to what else is going on in your system that you'd identify the 350B as having a particular midrange quality (vs. everything else) in your system that was good.
The 350B really comes into its own when used with a Bendix 6106.
You bring up a good point that new Supratek owners should take notice of. The Suprateks are ridiculously sensitive to microphony (not a good thing). I really don't know a linestage preamp that is more sensitive. You essentially need phono-grade quality tubes for line-grade application. If I had a gripe about the Supratek design, this would be it. And for this reason I hate selling 6SN7 to Supratek owners.
I agree the CV181 does not work in my preamp. I think you may have misread what I posted. It's a tube that I do not recommend (for the Supratek or for nearly all other 6SN7 applications).
I have Ken Rads with identical base prints - down to the alphanumeric date codes - but clearly different builds (tin versus copper grid posts, different mica varients, etc.). There might be audible differences as you say (I still can't hear marginal differences myself, much less "dramatic" ones). Whether you or I believe there are sonic differences or not, base print is a virtually useless criteria.
I also find the 350B midrange very neutral, which is what I love about this tube. In comparision, the EL34 and EL37 midrange is a touch bloomy and warm. The 350B sounds fast and accurate. It does not, however, sound powerful IME. There is a leaness to the presentation that (reminds me of KT66 tubes) compared to EL37 and 6L6 tubes. The 6F6 also has possesses this leaness, and it too is very fast (faster even) and "accurate" like the 350B.
IME, the Sylvania Bad Boys is comparitively "dry" sounding versus the Tung Sol's more liquid, "wet" sound. For clarification's sake, I am not using the adjective "dry" with any negative connotation. It's a matter of perference. I like the Bad Boys; they've got better control of attack and decay then the Tung Sols, and the Sylvania 6SN7GT '52 have more spatial seperate and thus sound slightly more resolved. The high frequencies have an uncanny air to them. However, the Tung Sols simply reproduces harmonics that is extremely beautiful to my ears .... a bit more full and palpable. And they sound more balanced from top to bottom.
I confirm the problem with the 6106 regulator when use for the Chenin. There is no problem on CD source. In fact you can crank up the volume to the max (no music playing) and you will not hear any hum at all or tube rush sound. Not for the phono section though! With the 6106 as a rectifier, using the same test method, there is a loud "chugging" sound when the volume pot reached about two O'clock.
So for the Chardonnay, the 6106 will work without problem since the one that is affected is the phono section.
I was using 6F6G on my Chenin. But I am now enjoying a GE 7518 as regulators. It adds a little "muscle" to the already superb phono section (not that I am complaining!). I like the RCA 6L6GC'a also.
It seems to me, after reading a lot of comments and experiences about regulators and rectifiers, that the Syrah, Chenin, Chardonnay and the other preamps have a different voltage requirements. I think as far as the tube rolling issue is concern, the only tube that is "universally acceptable" based on others experienced to everybody is the 6SN7's for the Suprateks. The others vary and should be specific to each model only.
Amandarae - Are you sure that you are using the 7518 or is it the 7581? The 7518 only has a 2.5v heater and if that is what you are using you might want to get the fire extinguisher handy. You are right about different voltage requirements but the difference is mainly between the linestage only versions and the full-blown preamp with phonostage. SupraTek owners with the phonostages will have higher current requirements that will restrict the use of some of the lesser rectifiers and pentodes.
Anyone who has a phonestage in their SupraTek preamp might want to check with Mick before rolling power-suppply tubes.
My mistake! It is a 7581 (GE with pink base). I made a typo on my post.
".... linestage only versions and the full-blown preamp with phonostage. SupraTek owners with the phonostages will have higher current requirements that will restrict the use of some of the lesser rectifiers and pentodes...."
Exactly! This is the main reason why in the phono stage, the "chugging" sound was produced since the 6106 is basically a 5Y3GT isn't it?
I'll be a little while before using these, as my Sauvignon is brand new (today!), but for what it's worth Mick sent me these NOS tubes to play with:
6SN7GTA Australian-made by AWV "Super Radiotron". Black base.
Italian Fivre 6F6GT NOS tubes. Black base.
As soon as I get a chance I'll post some observations as I haven't seen these mentioned, nor have I seen these at any NOS tube dealers.
If any of you guys have a NOS Bendix 6106 that you have tried and don't like. I would be interested in purchasing it.
Mine just died !
I turned my system on earlier today and let it warm up for about an hour and when I hit play....nothing. The tubes in the linestage were glowing, but the 6106 was cold.
Just drop me an email and I will get back to you asap.
Thanks in advance.
PS - I've got to go back and see who I purchased this tube from. It was a retail tube seller and it was sold to me as NOS. The tube base looked really discolored when I got it (I know that doesn't always mean anything), but I bought this tube as NOS. It can't have more than 100 hours on it.
Could have just been infant mortality or it could have been a used tube to begin with.
Here are my listening impressions of the 6106, GZ33, and GZ34 rectifiers in my system. These listening impressions were with the 6F6G in the regulator position. Beefy regulators with high plate dissipation may tend to reduce the audible differences between the rectifiers. In my system the differences between rectifiers were easily recognized. The Cabernet sounded great with all of the rectifiers I listened to. It all comes down to personal preference.
6106 - Some leanness from about 300hz on down. The rectifier WAS detailed and very good but gave up some pitch resolution in the bass compared to the GZ33. The 6106 required 24 hours continuous use before it even started to open up.
GZ33 - The warmest of the 3 rectifiers in terms of freq response. Excellent low-level resolution. I've used this rectifier for about 18 months. The GZ33 required about 4 hours use before it opened up.
GZ34 - This is the Amperex BugleBoy metal-base with double-getters. The measured freq response in my system was similar to the 6106. There was the same leanness from 300hz down. This rectifier gave me the highest resolution of the 3 rectifiers. It was very airy with excellent harmonics and the best pitch resolution in the bass. The GZ34 required about 4 hours use before it opened up.