SET amp owners thread

[morricab]

I don't have a lot of experience with tube amps, especially separates, just last year or so. I will say the sound of the Thoress pre and amp can be tailored by the tube choice. Which makes sense , point to point wired and no circuit boards, the tube should make a big impact on sound. I've been surprised though that the 300B tube hasn't changed the sound of the amp/preamp combo quite as much as the tubes in the line stage and phono stage of the preamp. The Sofia Princess 300B sounded good, then one went bad and got a Gold Lion pair to replace them. Like the Gold Lion too, not quite as quiet as the Sofia's, but not loud either. Just some crackle at warm up that goes away. The change in 12SN7GT tube in the pre, from NOS RCAs to Sylvania, some others. These aren't expensive tubes, and thankfully when bought pre I got a few boxes of tubes, mostly various 12SN7GT pairs. It is surprising just how much it changes the sound. The RCAs I have are kind of punchy and not as detailed on the preamp, but very fun to listen to. Some of the others are more clear and linear and not as "analog" sounding. I kind of expected the 300B choice to make more of a difference in the chain, and it still might. I've only tried a couple. It is fun though how the tubes in the line & phono stage in the preamp change things, it's very noticeable tube to tube. Does anyone have a recommendation of a 300B tube pair under $300 to try?

I have TJ Full Music mesh plates that sound very nice. Way better sounding than basic Chinese ones I had before. Not as mid range focused with better extension on top .

 

[acousticsguru]

I have TJ Full Music mesh plates that sound very nice. Way better sounding than basic Chinese ones I had before. Not as mid range focused with better extension on top .

When you say "basic Chinese", are you referring to Shuguang? There's one aspect about those that I've always thought fascinating, which is that if +/-15% emission is sufficient to form a so-called matched pair (it's really not sufficient, but the basis on which we're being sold so-called matched pairs today, as using a curve tracer would seem out of the question, given prospective buyers would hardly be willing to pay for the man-hours involved), then almost any two randomly picked Shuguang will form such a pair - and the same is apparently no longer true for more recent Chinese tubes by brands aficionados tend to refer to as "better" (I have little experience with Psvane, of which the ones I've tried sound rich and warm, and none at with Linlai).

Greetings from Switzerland, David.

 

[Atmasphere]

I have TJ Full Music mesh plates that sound very nice. Way better sounding than basic Chinese ones I had before. Not as mid range focused with better extension on top .

You might try the LinLai too.

 

[morricab]

You might try the LinLai too.

I am not so much a tube roller...the TJs are fine for me as I don't want to spend more on the 300Bs than the cost of the amps themselves...

 

[Atmasphere]

I am not so much a tube roller...the TJs are fine for me as I don't want to spend more on the 300Bs than the cost of the amps themselves...

I get that! I was referring to the 6SN7 though FWIW.

 

[acousticsguru]

I get that! I was referring to the 6SN7 though FWIW.

I happen to own a number of NOS 6SN7s, VT231 (and equivalent with adapter), but once I tried Melz 1578, I forgot all about rolling, never got to try all I have (I live by a self-imposed audiophile principle that says I'll stick with what I like, maybe add more, but for as long as I'm happy, not swap or change). I'd originally planned to roll Linlai Elite, maybe someday…

Greetings from Switzerland, David.

 

[tinkerphile]

I had a similar reaction when I first installed my Duo Mezzo’s in my room. Adding Thomas Mayer silver 10Y line stage and 45 Drives 45 amps was “icing on the cake”. Glad you are enjoying your Duo Mezzo’s, KPZ.

I really quite interested in those speakers; I just have to find a location to listen to them for a couple of hours. It is tempting to lump them in with typically observed horn deficiencies/downsides, so I've overcome that prejudice, and now it is time to listen. If they do what many owners say, then the price seems to be very fair. I currently own DeVore O/96 and love the tonal reproduction on certain types of music, but believe some other genres reveal limitations - not bad or poor, mind you, just limited.

 

[tinkerphile]

I think you can easily see what is going on- in the old days they simply used the word 'efficiency' as in the JBL example I gave and later simply changed the word to sensitivity, which really isn't how it works and for the most part no-one cares.

In order to know when you are applying 1 watt, you have to measure the impedance of the speaker at the frequency at which the power is being applied and then to the math to determine what voltage to apply to know when you are at 1 watt. The sensitivity spec is much easier since you merely apply 2.83 volts- and this is part of the reason sensitivity has taken over (this is also why digital took over since its so much easier to use in the recording studio). FWIW, '2.83volts' might seem quite arbitrary to many reading this, but it makes more sense when you know the legacy (which is what we've been talking about) is 1 watt at 1 meter assuming an 8 ohm load.

In any event, when you are using a zero feedback tube amplifier the efficiency spec is more useful since the amp can't double power as the load impedance is halved.

One area where this can get particularly pesky is when the speaker employs dual woofers in parallel. In such a case, the midrange and tweeter have an 8 ohm impedance and efficiency that is 3dB higher than that of the woofers, but the dual woofers cause the voltage source amplifier (IOW, solid state amp) to put out twice as much power into that woofer array and so the woofers keep up with the rest of the drivers. But when you put a power source amplifier on that speaker, such as an SET, you'll find that the amp is not making enough power for the woofers and so the system will have less bass and will be tonally tilted towards the highs. Although its not likely to be used with an SET, the B&W 802 is a good example of a speaker like this and there are many more as high end audio is plagued with designs like it. They are no good for zero feedback tube amps and not great for tube amps employing feedback (which can allow them to act like a voltage source but instead of doubling power as impedance is halved they halve power as impedance is doubled; part of why tube amplifier power is so expensive) either. I don't think they do solid state amps any favors either- the last thing you want any amplifier to do is work hard for a living- it will make more distortion and that distortion will be audible as less detail, brighter and harsher.

If there was ever a reason to be suspicious of the sensitivity spec when it relates to SETs this is it!

So when you see a loudspeaker that has a 96dB sensitivity spec, do your due diligence; do the math and convert the sensitivity to efficiency by looking at the impedance of the speaker. If its 4 ohms subtract 3dB from the figure...(while 96dB might be barely usable with an SET, 93dB simply isn't unless you are nearfield in a smaller listening environment). If it has a dual woofer array and is '8 ohms compatible' be very suspicious- there is a very real chance it won't work as expected with an SET. In this way you'll get a better idea of whether the speaker is a candidate for your amp.

Now there is a lot of 'common wisdom' (which might be a type of oxymoron) that you get the speaker you love first and then the amp that drives it. But any SET user knows that isn't how it works. SET users feel that SETs are the kind of amp that really brings home the music, so for them they have chosen the amplifier first- now they have to sort out what speaker works. This is why knowing the difference between the sensitivity spec and the older efficiency spec is so important to them.

(And FWIW since our OTLs also do not use feedback, this is a topic that I've been dealing with literally for decades; back in the 1970s I realized that if the speaker demanded that the amp have feedback, there was a good chance it would never sound like real music. This was and is because most amps that can behave as voltage sources lack the required amount of feedback to sound right; when you don't have enough feedback there will be distortion added by the feedback itself through the process of bifurcation of the input signal when combined with the feedback at the feedback node in the amp. No solid state amp made in the 1980s and most of the 1990s or before ever had enough feedback which is why there is a tubes/solid state debate. insufficient feedback will cause the amp to sound bright and harsh; typical solid state complaints. IMO/IME this is why there are still tubes around for audiophiles.)

I realize this reply is en retarde, but for those just accessing the thread/post, your excellent commentary reflects some of what John DeVore has also been on about. Thank you for taking the time to provide a very insightful explanation - it's one of the best I've seen and is valuable information.

 

[AB76]

I have TJ Full Music mesh plates that sound very nice. Way better sounding than basic Chinese ones I had before. Not as mid range focused with better extension on top .

Thank you. I'll try them.

 

[bonzo75]

I really quite interested in those speakers; I just have to find a location to listen to them for a couple of hours. It is tempting to lump them in with typically observed horn deficiencies/downsides, so I've overcome that prejudice, and now it is time to listen. If they do what many owners say, then the price seems to be very fair. I currently own DeVore O/96 and love the tonal reproduction on certain types of music, but believe some other genres reveal limitations - not bad or poor, mind you, just limited.

That's because you are using Pass. That's a poor match. You should get NAF 2a3 or Airtight 300b used. There are others as well but have heard Devore directly with these compared to other amps. They work much better in that 10 to 12 watt range

 

[AB76]

You might try the LinLai too.

Thanks for the recommendation. Like your name, I'd love a pair of Atmasphere OTLs one day. I might need more room first

 

[AB76]

I happen to own a number of NOS 6SN7s, VT231 (and equivalent with adapter), but once I tried Melz 1578, I forgot all about rolling, never got to try all I have (I live by a self-imposed audiophile principle that says I'll stick with what I like, maybe add more, but for as long as I'm happy, not swap or change). I'd originally planned to roll Linlai Elite, maybe someday…

Greetings from Switzerland, David.

Thanks, appreciate the suggestion for the pre tubes

 

[tinkerphile]

That's because you are using Pass. That's a poor match. You should get NAF 2a3 or Airtight 300b used. There are others as well but have heard Devore directly with these compared to other amps. They work much better in that 10 to 12 watt range

Well, I'd think it is an overstatement to say Pass Labs amplification is "a poor match." I spoke on the phone with John DeVore before purchasing the 96s, who believed the Pass amps work very well with them. That said, I get the optimal voicing is likely an SET, etc., and NAF is a good recommendation in the tube side of the equation. However, low powered tube amps are also only optimal under certain listening conditions; that is, they also have their limitations, especially low-powered. Ultimately, I'd like to have both - - if I could only figure out a way to easily switch amps. I've been over this with industry experts here on WBF and elsewhere. For the present, I've determined to incorporate a GA TRP balanced direct (with VC) to the Pass, and begin experimenting with various tube combinations to "balance" the SQ equation.

 

[cal3713]

Well, I'd think it is an overstatement to say Pass Labs amplification is "a poor match." I spoke on the phone with John DeVore before purchasing the 96s, who believed the Pass amps work very well with them. That said, I get the optimal voicing is likely an SET, etc., and NAF is a good recommendation in the tube side of the equation. However, low powered tube amps are also only optimal under certain listening conditions; that is, they also have their limitations, especially low-powered. Ultimately, I'd like to have both - - if I could only figure out a way to easily switch amps. I've been over this with industry experts here on WBF and elsewhere. For the present, I've determined to incorporate a GA TRP balanced direct (with VC) to the Pass, and begin experimenting with various tube combinations to "balance" the SQ equation.

Ked always speaks in absolutes, but it is true that unless you've listened to your speakers with a low-powered option, you're only guessing at the SET limitations.

I had Coincident Super Eclipse IIIs, first with a Pass INT30A, and then with the 8W Coincident Frankenstein 300b SET monoblocks and the SETs were better in every facet. I later upgraded to the Coincident Pure Reference Extremes and they were less efficient. After much amp auditioning (Digital, SET, OTL, Class A SS) I ended up with First Watt F4 monoblocks.

All to say that reading only gets you so far. In home listening on your system, with your source, in your room, with your ears is the only way to truly know.

Best of luck, either with new speakers, or by perfecting the DeVore balance.

 

[tinkerphile]

Ked always speaks in absolutes, but it is true that unless you've listened to your speakers with a low-powered option, you're only guessing at the SET limitations.

I had Coincident Super Eclipse IIIs, first with a Pass INT30A, and then with the 8W Coincident Frankenstein 300b SET monoblocks and the SETs were better in every facet. I later upgraded to the Coincident Pure Reference Extremes and they were less efficient. After much amp auditioning (Digital, SET, OTL, Class A SS) I ended up with First Watt F4 monoblocks.

All to say that reading only gets you so far. In home listening on your system, with your source, in your room, with your ears is the only way to truly know.

Best of luck, either with new speakers, or by perfecting the DeVore balance.

Thanks for the feedback. Much appreciated. In terms of limitations of SET/some tube amps, I should have said primarily playback volume limitations.

 

[morricab]

Thanks for the feedback. Much appreciated. In terms of limitations of SET/some tube amps, I should have said primarily playback volume limitations.

Just get an Aries Cerat amp...then you won’t worry about sound quality...or quantity

 

[bonzo75]

Well, I'd think it is an overstatement to say Pass Labs amplification is "a poor match." I spoke on the phone with John DeVore before purchasing the 96s, who believed the Pass amps work very well with them. That said, I get the optimal voicing is likely an SET, etc., and NAF is a good recommendation in the tube side of the equation. However, low powered tube amps are also only optimal under certain listening conditions; that is, they also have their limitations, especially low-powered. Ultimately, I'd like to have both - - if I could only figure out a way to easily switch amps. I've been over this with industry experts here on WBF and elsewhere. For the present, I've determined to incorporate a GA TRP balanced direct (with VC) to the Pass, and begin experimenting with various tube combinations to "balance" the SQ equation.

It is not about SETs vs SS. It is about Devore. By adding GA TRP you are not solving the problem, it is not about balancing valves with SS, trying to get best out of both. It is a misunderstanding that SS has punch, drive, bass, dynamics compared to a SET. That is only when SS is matched to a speaker that requires grip and has impedance drop, and SETs cannot handle it, so SETs sound slow and flabby.

Devore responds better to lower watts. I have compared jadis 100w integrated, Riviera hybrid 50w, Silvercore 833c 20w, and NAF 2a3 12w in the same room. NAF sounded much better. And in another roI have also heard it om Airtight EL34, 34 watts vs Airtight 300b, 10watts. Again the 300b was much better. This is not for all speakers as on some the 300b and NAF will just not have enough headroom. But on devore they do.

Separately, I would not recommend Pass even if a speaker required SS. Pass has a flowy class A tone that initially sounds nice. not bright like some SS, but it has a restricted dynamic range and the Pass color is always there. The top phono and preamp are worse. In fact their best product is the first watt stuff

 

[tinkerphile]

Just get an Aries Cerat amp...then you won’t worry about sound quality...or quantity

How I'd love to get one. I can't believe I hadn't incorporated my continued hifi obsession in my retirement plan. What was I thinking!?

 

[acousticsguru]

Thanks, appreciate the suggestion for the pre tubes

You're welcome! By "equivalent with adapter", I meant NOS 6F8G, by the way, which can be found for comparatively little money (probably because of the need for adapters, not everyone realizes they can replace 6SN7 in a preamp or integrated). Again, I haven't yet tried those simply because the Melz 1578 sound so complete and coherent in every respect that I decided to not give in to audiophile restlessness, despite my inborn curiosity. I've literally seldom heard a tube where even after several months I couldn't point out a specific shortcoming. I'm keeping my fingers crossed these will be as long-lived as one might expect of military equipment, and in meantime started hoarding more (I tend to do that with wine and tubes once I find something I really like, figuring I'll always be able to sell what I may end up not using). I won't ever claim there the best 6SN7 for every purpose, but in an integrated amp that's virtually hugging the listener with its lush sound like the AS-125, using Telefunken ECC83, Melz 1578 and AN-4242E, it is merely adding to a more open, focused and transparent character, with no risk of anything ever tipping toward the analytical side of the spectrum - if that were what one wanted, it's the wrong amp. By comparison, the stock Novosibirsk 6H8C tubes sound not bad but dry, the alternative stock Shuguang 6N8PJ perhaps a bit nicer, but some beautiful tall-glass Tung-Sol 6SN7GTB tend to steer the listener's attention to a soft and cozy midrange, which effectively takes away from the overall experience of listening to music (as the concentration is now on part of the whole, an effect of using gear to reproduce music, not what I'm looking for as an audiophile). The problem with all this is that it's almost impossible to give meaningful advice when it comes to tube-rolling, with a rare handful of tubes that simply are standouts in their category. The Melz 1578 (which is really a military version of 6H8C) may be one of those, as are probably all three I'm currently using in this amp, but again, there's only so much in this hobby one can say with certainty. Someone else may use these in a completely different amp, with a source or speaker or a room that needs taming, with the intent of taking their system into a different direction etc., and there's no arguing over taste.

Greetings from Switzerland, David.

 

[matakana]

It is not about SETs vs SS. It is about Devore. By adding GA TRP you are not solving the problem, it is not about balancing valves with SS, trying to get best out of both. It is a misunderstanding that SS has punch, drive, bass, dynamics compared to a SET. That is only when SS is matched to a speaker that requires grip and has impedance drop, and SETs cannot handle it, so SETs sound slow and flabby.

Devore responds better to lower watts. I have compared jadis 100w integrated, Riviera hybrid 50w, Silvercore 833c 20w, and NAF 2a3 12w in the same room. NAF sounded much better. And in another roI have also heard it om Airtight EL34, 34 watts vs Airtight 300b, 10watts. Again the 300b was much better. This is not for all speakers as on some the 300b and NAF will just not have enough headroom. But on devore they do.

Separately, I would not recommend Pass even if a speaker required SS. Pass has a flowy class A tone that initially sounds nice. not bright like some SS, but it has a restricted dynamic range and the Pass color is always there. The top phono and preamp are worse. In fact their best product is the first watt stuff

What do you have to say about the Riviera hybrid ? thankyou.