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Is SET just over that hill?
A little clinical history...My first high end amp was a Hafler 500.
Then I saw the light and got a Conrad Johnson MV55.
I just now finished the final touches on a variation of the Ralph Power PP 6b4g amp..I use 417a/IT/PP2A3 with no negative feedback.
A few years ago I went to a dealer and he had the VTL amp that you could switch from pentode to triode. The difference was obvious.What is not so obvious was the PP DHT's to SE DHT's. I understand theoreticaly why SE is better than PP but I just can't seem to hear it!
I go to CES and hear how the pro's do SET and I still come away with the same impression...they sound polite but rather thin. Nothing that I hear makes me want to go home and build an Set RIGHT NOW!!!!!!!
I guess it's an Illness that I have to live with...***sigh***
Follow Ups:
Maybe the difference between PP and SET is more a difference between pentodes and DHT, as most PP designs use pentodes, either triode strapped or not. Those of us that have PP DHT, 6B4G or otherwise, have the best of both worlds. There is a drive that my amp produces without losing the sweet mids of SET, and it produces the holographic imaging as well. The bass is tighter and more controlled IMHO.I'm sure others will argue the point but I'm happy with what I have, my 6B4G ST-70. I still turn it on every day and sit in awe over the sound considering it cost me less than my cheap HT receiver.
You have good ears but I believe that you have yet to stumble into the right opportunities. And maybe in some way you have an inkling of an idea of what might exist out there.
I had a VTL amp too that did the the pentode/triode thing and I could hear the difference. I had some vintage pentode amps converted to triode amps and I could hear that too except that the Eico HF81 seemed to sound good in both modes.I know what you are talking about too with the sound of SETS at shows.
I have a real nice DIY 6b4g amp, I think that's what it is, sitting somewhere on a shelf. It is very well made and I'm sure it is a good example of one. I'm not going to say how bad it is compared to the SETS I have. I gave it another chance about a year ago and now I'm not even sure where I put the amp. It's sitting somewhere here and it is very unlikely to ever get another chance.
The OTLs I have are really pretty good, way better to me than the VTLs I had and way better than the Cary V12 I heard before I bought them. But I have heard some good push-pulls. Doug on this forum built one, and I heard a real good one at the VTV show in NJ.
SETs potential is way beyond all of it. The tubes themselves, 45, 300b, etc., are way beyond any other type of output tube. There is just no contest there. But in close examination, an examination at home, you can hear the fundamental differences between P-P and SET.
There are things that the SET sound has that the others don't. But you have to strip things down right, and you have to carefully select some important ingredients.
Fundamental differences are related to variables like immediacy, presence, "involvement", and the type of soundstage. There is a certain 'in the roomness', a certain reality to the sound, that the other typologies don't have. The soundstage, with the striping down, and perhaps its a ac/SET effect, is fundamentally different that any other type of soundstage. I cannot say how important ac is on all the tube filaments, but I have a feeling that it has something to do with 'breathing life' into the sound.
I'd have to say that SETs potential is a fundamentally different animal than any other sound. Other sounds can have their wonders too, I know that is true. There are even unique characteristics to SS.
But the 'fundamentally different animal' in SET sound, is an sound heaven like no other. It is something that some audiophiles are going to want to reach for because of what it offers, if they knew it existed.But it is not just 'there' necessarily. It's kind of like a wild animal: you have to begin a search for it. It takes a while and you have to know what you are looking for as you go along. Once you are on it, it is easily recognizable and everything else then sounds remote and secondary. Even a little like fool's gold.
Sound is sound. Great engineering feats have broken into what it offers: Western Electric being one of the now vintage pioneers that has done so.
Kind of an interesting field in that some of the greatest achievements are in its history.
The field tramples along. But we are all on the verge of what it can offer.
Along SETS potential, I forgot to add 'rawness', as a characteristic.When was the last time you even heard a 'raw' sound? Rawness is something excluded from audiophile sound. It might have been taken out but it certainly was not added in or searched for.
So the unique characteristics of SET potential would be immediacy, involvement, presence, in the room, rawness, and a unique type of soundstage: one that just sounds real.
GOOD SETS are three dimensional in a way that no other topology seems to be able to match. This is something that your excellent description already eludes to but perhaps not with enough emphasis!Also, like other amps not all SETs are created equal and perhaps it's just a simple case of hearing the right one, matched properly with the right components. We all know how important speakers are but IMO a good TT source will magnify the differences between PP and SET.
Rgds,
Naz
Dimensionality is an important noticable aspect, more so with the 300b and two-way speakers. Like a wall of sound and dimensional at the same time.I noted before that the sound comes towards the listener more than with other amp typologies: the space between the speakers and the listener.
I experienced the 'aural matrix' but kind of forgot what it is because I went to a sound space beyond it. I only did it about 5 times and it has not happened in a few years. I call that space a 'sound terrain".
A 'sound terrain' is a 3 dimensional space that you actually seem to step into. It encompasses you as the sound is past you too. It is like being in a moonspace with the sound being like big boulders on the terrain all around you. That is the best way to describe it. It is a very unusual phenomena.
It is kind of like an epiphenomena. It is not vital: it is only the most interesting sound experience I have ever had but I don't feel compelled to go there. And it is practically damm near impossible to get there anyway. I don't know how much the mind has to allow you to go there.
It took place in a very small room. The speakers must have been positioned in a very certain way. I used a very dimensional 300b amp and I maximized the dimensionality further by using a dimensional cd player, and older Sventlana 300b tubes which are slightly more dimensional than the TJ's which are also pretty dimensional.
The whole experience is almost kind of embarrassing to talk about because it is really outthere. Kind of like another world but it is as real as real can be. I'd like to go there again to study it but I don't know if it will ever happen again. It's kind of surreal almost like a Dali, or some other art stuff I have seen where you see like unusual figures on a landscape.
If it's like a 'hologram', you are in the hologram like the hologram and the mind are one.
I experience a phenomena where artist floats in space before you in virtual 3D and the soundstage has real depth every time I sit down to listen. Curiously, the effect is less dramatic after some listening but it always remains three dimensional. In comparison, UL PP is a flat sheet. Everything is there but the depth ... very 2D! PP with minimal NFB and triode operation manages some of the magic but nothing comes close to a good SET. On this we absolutely agree!BTW, my speakers are big ESLs with dynamic mid bass driver arrays and subs only for the lowermost frequencies. Unfortunately you have to be sitting on the centreline to achieve what I'm describing but I wouldn't trade them!
Rgds,
Naz
that the 3D effect works for all DHT SETs with no global NFB in my experience including 845s, 300Bs 2A3s and 45s (mine are 845s). I have noticed though that a good HF response is important and mids too to a lesser degree. I strongly believe that preservation of phase response throughout the entire frequency spectrum is mostly responsible since spatial cues are heavily reliant on phase relativity. To my mind its this type of distortion that SET topology controls better than others.Naz
I don't have a clue what 'phase' is, so I don't know.
maintaining accurate phase through the full range of audio frequencies from input to output. Every reactive element in the chain has the potential to "distort" phase by leading or lagging (the OP compared to input). This is true at the frequency extremes where the reactive components form a filter and the frequency response begins to fall.What I am suggesting is that if an instrument produces a fundamental of say, 1000Hz it may produce many octaves of overtones. It's relatively easy to design and build an amp that maintains phase accuracy on the 2ndH of 1KHz fundamental but less so at much higher frequencies. So in effect the 9thH may be phase shifted compared to what was input and this shift (compared to the fundamental) could IMO lead to incorrect spatial cues. Playing with phase shift is basically how pseudo surround sound works ... it tricks the ear.
NFB can exacerbate the problem. You can imagine how complex the scenario might become by feeding back phase shifted harmonics (relative to the feedback point) especially if the signal contains varying degrees of phase shift at different frequencies.
The best way of controlling the complex situation is to build a very wide band amp with zero global NFB (common wisdom). Local NFB can also be a problem but this is much easier to control through proper design.
Naz
This is kind of DHT talk, but my own system is balanced PP so not totally analagous. It's also totally DHT beginning to end. My observations are that I get more "dimensionality" in space with IDHTs. The DHT experience is right on the speaker, precisely and utterly in the plane of the speaker. So with nothing but DHTs the sound field is quite flat, but VERY immediate, kind of startling in fact. I don't have the opportunity to create soundstage illusions. But I get a whole other kick out of it, which is tone, tone, tone and more tone. The tone is startling - cymbals are totally metallic and shimmering with all the HF energy you expect - you pretty much can see the things right in front of you. Snare drums have snap, rim shots are exactly right - etc etc etc. I'm an ex muso so spent a good 20 years playing jazz on double bass with a drumkit right next to me, and it's the most lifelike reproduction of a drumkit - just in terms of tone - that I've ever heard.So I'm wondering if the holographic stuff isn't coming from
a) SET
b) The IDHTs in the system.
I don't see it coming from the 300b stage just in itself - I reckon there's more going on. If you want the effect, then you may even have to sacrifice the total DHT experience. Not something I'm willing to do, personally.
Am I making sense here? Just wondering if others have had the same kind of listening experience with total DHT and hybrid DHT/IDHT? Andy
That's probably a pretty on-target assessment.But let's not come to a final word about it since it is a work in progress to some extent.
I think my most dimensional amps are the 6sn7/300bs. The 6sn7, especially with a fi primer circuit. At first I attributed some of the dimensional attributes to the opts but later realized that alot has to do with the fi primer 6sn7 circuit.
I agree to that the effect might not be there with the dhts, and that idhts are a key especially say the 6sn7, a double idht, with what seems to me to be a little mystical sounding fi primer circuit. I really kind of like the sound of that circuit.
My favorite amp, by the way, is a 6sn7/26/45. It is not necessary a fully dimensional amp. But just think about what that might throw into the equation: idht/dht driver set-up.
My home brew Phono / Line stage drives my SETs and it exclusively uses IDHTs. It also happens to enhance the 3D effect more than any other Phono stage I've tried, providing exceptional detail and HF response.Funny you should mention DHTs and tone. I tried 26s in lieu of both 6922 and 6H30P in my Phono stage and contrary to other opinions thought that the result was not as extended as the IDHTs. Although the 26 had a nice midrange tone overall I preferred the latter. Interestingly some of the 3D effect was also lost with the 26. I've observed this with many DHTs including some very popular tubes and maybe the right mix of DHT tubes is most important in an all DHT design to prevent limiting HF response too much. My take is that good HF response is a must for holographic imaging but the immediacy of SETs is perhaps the major contributor.
Like you, I too achieved some of the effect with PP but only where the OP tubes were wired in triode mode, which also happened to provide greater immediacy. I'm certain that you can produce 3D to a greater or lesser degree with most types of tubes and even topologies but I think SETs do it better than anything else. DHTs with good HF response work well but if the design implementation is skewed mainly towards great midrange tone at the expense of HF, some "space" will be lost. Often IS coupling is the culprit here unless VERY good trannies are used.
I still think that phase preservation is a must and this stacks up technically with extended HF and little or no global feedback. But but on reflection I think you are right about IDHTs to some extent and perhaps my explanation of frequency and phase response remains consistent with your findings. Maybe a mix of both DHT and IDHT brings about a great marriage in this regard.
Rgds,
Naz
The lack of treble in the 26 has been referred to by a few people - it does appear a bit flat on top. For a full sound with good top, try the 12A or 01A, or the 30 which has excellent top but a rather thinner sound. There are some distinct flavours in the DHT cookbook. I'd suggest you experiment a bit more with a greater range of DHTs. I went through a load of them by using bench supplies for the filaments - I just dialled in the right voltage and swapped tubes. I've personally found some nice mixes of DHT that I find promising. The cheapest is the 3A5 which is really peanuts - not the best, but pretty good indeed. Useful double triode, which could probably mate well with another double DHT the 1J6 as a driver. Must try that.I must take a look at SET - never had one but not too hard to build and I have the parts. I hang out here to discuss DHTs!!!
Is a match made in heaven.I have 26's driving various output tubes and I'm a big fan of the tube. But it leads to something very special, perhaps unique with the 45.
I've been talking to Josh about a GM100 driving a 2A3. :)Can you say MUTANT?
Maybe a GM100 linestage....
Later
D
I did try a 2a3 linestage, but it wasn't the equal of some of the other small DHTs. Others have tried 300b linestages. Haven't heard of a 211 or 845 linestage yet!!
Have you tried 10/801 or 316?These make up very good linestage amps.
Later
D
There are some radio transmitter tubes, that are 6ft tall, and crank out over 1000W in SE deep class A. Those would make quite a line stage! :)))10 kilovolts on the plate, generate enough X-rays to kill anyone within 20 feet overnight.... sadly, the death of a janitor who mopped the transmitter room on top of the Emipre State Building lead to the discovery that 5+ kilovolts on the plate generate humongous amounts of X-rays..... enough to ignite A-bombs. Special tubes that had focused x-ray bombardment were developed for that puprose........ probably pretty powerful sounding for that split second before the blast. ;)
Janos
If you had a three-way speaker and could use a SET for only one of the drivers, either woofer, mid range, or tweeter, what would it be?What would be your output tube and transformer impedance?
Say the mid’s band pass is around 250 to 1k6.
Russ
Hey Russ, an easy question deserves a simple answer, the SET should drive the mids and highs. As for the OP tube, I'm not as polarised as some and would choose the appropriate tube based on the power I needed ... as long as it's DHT. My speakers are only about 90db efficient and they are in a huge room so I chose 845s but I've worked with everything from 45s up to 300Bs and they all sound great. Primary impedance depends on the tube but I tend to trade off a little power for greater linearity by keeping impedance slightly on the high side.For sub implementation I'd preferably choose full range main speakers and feed them with a full range signal directly from the SET. I'd augment the bottom end with a good (tight) sub(s) rolled off at very low frequency, 40 - 50Hz tops, with a steep crossover. This will depend on your full range speaker off course but you are only trying to extend the bottom end, not replace it with the sub. Even if your main speakers are down 6db at 40Hz there is no need to set a crossover point higher than this since the OPs will add. IMO the only unsuccessful sub implementations are those where the subs are doing the job of the mids or too much of the mid bass, or where the sub is simply a loose cannon!
Cheers,
Naz
"...they sound polite but rather thin."That's not what I hear, or at least it's not how I would put it - I hear more of what I would call "body" or "thickness" in SETs.
Be that as it may, it is possible that SET does not appeal to your taste, or serve your musical needs. Not everyone has to hear the same things, or the same way!
I find consistently that zero-feedback class A triodes sound better than any lesser arrangement, but the difference between SE and PP is more of a balance. I prefer the SE richness and presence, but I can hear that the best PP has a transparency that can be very beguiling. Some of the best ears in the business prefer it. The important thing is to identify your own preferences, and don't let Stereophile, the Asylum, or anyone else push you around.
My Welborne SET certianly doesn't sound thin.The difference I hear between PP and SET is that SET is more relaxed, like natural sounds while in PP I hear a machine working, trying to prove something.
Voices are single ended, all instruments in an orchestra are single ended. There was nothing in the world that was push pull until a relatively short time ago.
Son House
"There was nothing in the world that was push pull until a relatively short time ago."I wonder what you mean by "push pull".
"Voices are single ended..."Vocal cords are push pull. There are two of them working in concert. Both moving the exact same but in opposite directions. Very much like Class A push pull output tubes.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
I think of push pull as a system with two devices which run 180° out of phase.Vocal cords are push pull only in terms of location relative to each other. They function in phase with respect to the audio signal, the air passing by them. It seems to me that vocal cords are parallel single ended. I don't see how you would get any sound if vocal cords were out of phase.
An amplifer that uses 2 triodes in parallel does not become push-pull simply because you turn one of the triodes to face the other way.
One way to have a push-pull voice would be to have a machine sucking the air out of the mouth at the same time as the lungs are pushing.
Son House
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