As upgrade rush bites again, planning to perform some tube rolling on my Rouge Ares Magnum. Please share some experience with tube rolling on pure tube circuit topology phono preamps. Practical experiences are preferred. Theoretical options are welcome too.
@pindac no questions, advices of others with worthwhile experience is very valuable and of course could be implemented, but my senses and fillings r more important for me. You know it’s like advices from others which women is better for you… you listening to that advices but using your fillings in the first place.
I have a Zestos Andros Deluxe 2 that I've done a fair amount of tube rolling in. The Zestos has two 12AX7s in the "primary" spot, and an interesting pair of 12DW7s (one triode has an 12au7 like mu, the other having a 12Ax7 like higher mu), which according to Zestos drive the dedicated output transformers. I've rolled both positions, the 12 DW7 makes only a slight difference in clarity. I've tried Mullard 12DW7s, some American NOS ones... not much difference to be honest. I put in some NOS Orion DW7s (made by Tungsram) cause they look the coolest and I convinced myself they sound the best. : )
The 12AX7s do make a pronounced sonic difference though. In lieu on the stock JJs, I've tried several NOS including: Telefunken smooth plates, Tunsgram 12AX7, RCA black plates, Mullard longplate square getters, Amperex long plates D getters, and Tesla E83CCs. Long story short, the best sound came from the Teslas and the Telefunken in terms of clarity, bandwidth and detail. Close behind were the Tunsgrams, which although deviating from neutral, had a seductive bloom to them. The RCA black plates fared surprisingly well with a punch and clarity that I could've lived with. The Mullards sounded like a wet blanket over the speakers, and were not suited for this phono amp usage. All tubes were very quiet. I'm leaving in the Teslas. BTW, I love this phono amp. It frankly far surpasses the Pass XP15 that preceded it in all areas. The Zestos is completely quiet, with no overt tube noise. It's end game for me.
gakerty Mullards have never lasted too long in a phono stage or any other application here, for the reason you colorfully cite :)
The Zestos looks lovely and its use of an asymmetric dual-triode is very interesting! Use of output transformers is cool, too. I'd love to hear one some day.
Certain Tubes can be quite expensive and tube rolling can generate a considerable outlay for the items to be compared. I shared the pitfalls I had with the 6SN7 when I went alone on the subject of rolling these. I have 5 out of Seven Pairs of NOS and New 6SN7 Tubes that are rejected. A few of these pairs I will not sell on as they are not something I would like another to experience, I have no intention to reproduce the stress and the concern the use of them can inflect.
My later experiences where support from experienced individuals was at hand and the offer to assist accepted proved to be much more successful, and the choices made by myself have been keepers.
Ironically two friends that were consulted with, for advice on other Tube Models are also agreeing and promoting the same 6SN7 I have chosen as their preferred tube. One friend also thinks I am with a very good 6SN7 Tube and would like me to try the ECC33 once I have the approval of the Power Amp's Designer/Engineer to use it. The ECC33 was a Tube I was not even considering.
mulveling-- Those Mullards, despite their lore and hype, have never really found favor for me, either as gain tube in my Rogue ST100, nor here in the Zestos. I paid a fair amount for them, and really wanted to like them, but I suppose my ears and system don’t really need to be fattened up by the Mullards. : ) If I need thickening, the RCA black plate will achieve that, with no compromise on bandwidth.
I am indeed smitten with the Zestos, but it is my first tube phono amp, so I am new at phono tubes. It is just beautiful all around. I got a good deal on it here at Agon and jumped on it. I’m REALLY glad I did. Insert your audiophile cliches here: "veils lifted...." etc. : )
Another great and cheap alternative (NOS) for me was the Sylvania 12at7WA
Sylvania Gold Brand 12AT7WA is a high-frequency twin triode in a small 9-pin miniature glass package. This is a very rare military gold pins version from the 60’s, made in the USA. The 12AT7WA is found in many high fidelity applications, as each triode section in normal use operates as a class A amplifier. This tube is very low in microphonics due to its rugged construction. Sylvania Gold Brand is an extremely high demand vintage tube. Sylvania was a U.S. manufacturer of vacuum tubes, transistors and electrical equipment, formed in 1931. Their vacuum tubes from the 50’s and 60’s (Gold Brand series) are very nice!
I enjoy tube rolling, but there are three 12au7 tubes that I keep in a virtual rotation in no particular order: Mullard, Chelmer, and Telefunken. These three are consistently quieter than a lot of other tubes. I have a small collection of 50s, 60s GE, RCA (clear top in particular) that become noisy with ghosting and microphonics after a fairly short number of hours. Stick with my three recommended brands and you will be rewarded with stellar sound and stone quiet performance. My favorite of the three? Tough call, but I really like the Chelmers, and you can't beat the price!
Chelmers would be relabeled tubes from a large maker - could be USA or China. Probably USA if small signal. I had an old Hagerman Trumpet (wood tower type) that was supplied with Chelmer 6072 (12AY7) which looked like they were either old-stock Sylvania, RCA, or GE black plates.
The 6SN7 Tubes I have retained for use are Kenrad VT231 Black Glass and a Sylvania GT Tube. These are different in their presentation as an interface where they the input Tubes on 845 Monoblock Power Amp’s.
I would very much like to try other Vintage, and will most likely return to this when the Mono’s are converted to a Balanced Design.
Absolutely Correct about the ECC33, hence the advice given to myself to discuss this Tube with the 845 Designer/Builder.
It was Jaw on the Floor when the KenRad's were put into service. The KenRads and Sylvanias are both fine for ESL Speakers in my system. The Sylvanias are a little too rich for my my tastes when used and the Floor Standing Cabinet Speakers are in use.
@pindar. I've paired a Kenrad VT231 Black Glass with a Sylvania VT-231 in my amp. Two very different tubes providing dynamic holographic sound. And a Tung Sol BGRP in my preamp.
My 845 Mono's Input design is a little unusual as it has certain Tubes in Pairs that are only using Half of the Tube in the Circuit. There is only One 6SN7 Per Monoblock and these are only using Half of the Tube in the Circuit. It is always difficult to explain a Bespoke Built Design for the SQ, there is a separation in SQ and usually the only way to fully comprehend the designs capabilities is to be in the room with it.
It is very often the case that when dual triodes, like nearly all the tubes so far mentioned in this thread, are used in circuit, only one of the two separate triode sections is actually used. But what is a BGRP? Thanks.
BGRP - Black Glass Round Plate. I have a pair of 12AU7s Tung Sol black glass (grey standard plates, I think) that sound fantastic, with great extension, but they are lowly 12AU7s: )
It’s been a long time since I played with lots of vintage 6SN7, in a crazy headphone amp (and briefly later on in a Rogue 99 Magnum preamp). I do remember the Tung Sol BGRP sounded the most unique out of all, and the best to my ears. An extremely juicy, "technicolor" sound (like Koetsu) that was the only tube which seemed to fully deliver on the 6SN7’s purported promise as "king of tone". The Ken-Rad was my next favorite (especially BG variant), with bass 2nd only to the Tung-Sol. The Sylvania VT-231 seemed a little dry to me but was neutral and could be good in combination with Ken-Rad or Tung-Sol. I also liked the brown-base Sylvania 6SN7WGT, probably more than the tall bottle VT-231. I never liked the gray glass RCA VT-231 as much as these other makes, but it’s nonetheless a pretty good sounding tube. The Electro Harmonix 6SN7 sounded positively "solid-state" like by comparison.- a little grainy, and with a surplus of treble energy, but nice bass to balance it; honestly not too bad a tube for the money (and of course by now I’ve heard plenty of solid-state gear that is neither grainy nor bright). The Russian Tung-Sol 6SN7GTB sounds like a more refined version of the EH.
I also remember combining different makes seemed to stack only the positive attributes of each, rather than stacking or remixing the downsides (maybe this interesting quality is part of what makes 6SN7 so revered) - but if I’d ever had a full set of Tung-Sol BGRP, I probably would’ve just filled every slot with those. Problem is I kept getting used "nearly dead" ones that kept dying on me. It’s always been hard to find good ones and demand is so high people keep trying to offload duds.
For any of these old 1940s variants - GOOD LUCK finding a pair quiet enough to use in a phono stage or in the gain slot of a preamp. The old Sylvania 6SN7GTA/GTB 1950s "chrome domes" are easy enough to find quiet and in matched quantities, but aren’t as sweet sounding as the old tubes - they sound kinda like a slightly sweeter Russian Tung-Sol GTB in VAC 200iQ amps.
Now we are getting into the “icky” realm of ascribing magical sonic qualities to this or that tube based on loose subjective evidence or on hearsay evidence. Why I stopped rolling tubes at all, once I figured out what I liked, of course. Changing a capacitor, for one example, can have a much more profound effect on SQ. I guess it’s fun.
the Tung Sol BGRP sounded the most unique out of all, and the best to my ears. An extremely juicy, "technicolor" sound (like Koetsu) that was the only tube which seemed to fully deliver on the 6SN7’s purported promise as "king of tone". The Ken-Rad was my next favorite (especially BG variant), with bass 2nd only to the Tung-Sol. The Sylvania VT-231 seemed a little dry to me but was neutral and could be good in combination with Ken-Rad or Tung-Sol. I also liked the brown-base Sylvania 6SN7WGT, probably more than the tall bottle VT-231. I never liked the gray glass RCA VT-231 as much as these other makes, but it’s nonetheless a pretty good sounding tube.
My thoughts exactly, even down to your remarks about the RCA VT-231. Ken Rad Black Glass paired with a Sylvania VT-231 produces the best attributes of both tubes.
The only tube I've heard to rival the Tung Sol BGRP is the Melz 1578 OTK, Russian military. This is a magical sounding tube. I know these terms get thrown around, but a pair of these in my amp created a you are there experience, so realistic it was scary.
Unfortunately, the early years were the best and they're all gone. I have some from 1980 and for a short time I was able to enjoy them before they crapped out. Have one pair that works and I'm saving it.
The stamp of “OTK” is not about the brand or any tech spec… at old Soviet and Russian manufacturing “OTK” means Department of Technical Control passage. Usually checked and ready to ship products was stamped with OTK stamp.
Totally agree about a Cap' change having a profound effect. The Phonostage I am using has been auditioned in various circuits for the end design to be produced. When the prototype was almost complete and identified as being a very attractive performer. Curiosity was still with myself and a couple of Cap' and Resistor changes were encouraged to be undertaken that had been discussed and not as yet trialled. A Brand change of a Copper Cap with a different value and a few Z Foils was a remarkable change and the one I have maintained in my owned model.
@lowrider57 I have a very good friend, younger and with better ears than mine - he says the exact same things about that Soviet 1578 tube. Yes the vintage/make is supposedly very specific and very important. Something abut round plate holes too, etc. I’d like to try them someday but understand they will be very hard to find (unless I can pry a pair off my friend), and my main system is not currently married to 6SN7 tubes.
The OTK stamp meant it went through quality control and met the highest specs.
@mulveling There are a couple dealers in Russia and Ukraine selling various Russian tubes. A 1578 stamped on the glass with the multiple holes on the supporting rod is the real deal. Many sellers call their tubes Melz 1578, you just have to see the internal structure to know they are not.
The OTK stamp meant it went through quality control and met the highest specs
You right about passing through quality control… but too optimistic about highest specs…all Soviet NOS has to be carefully checked before using…we have to be specifically careful with tubes made in USSR in 80s - 90s cause quite control of this period was much lower than 60s - 70s.
@surfmuz , you are so right. I mentioned on another tube thread that I'm done with Melz. I purchased a pair of 1578 OTK from a dealer in Russia, 30 day returns. I loved them, ordered 2 more pairs. Long story short, 4 tubes had crackling issues, the remaining pair will reside on my shelf. I'll save them for a rainy day.
I found out later on a different forum about the poor QC after 1970s. Mine are 1980 vintage and can be restored by resoldering the connections inside the pins. A few owners who also bought the 1980s have done it successfully.
I can say that andy's tubes sells special graded phono tubes and driver tubes that will cut down on system noise and sound better at the same time, you should check it out before swapping a bunch of non graded tubes in/out of phono circuits.
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