Is it possible that the reason SET tends to sound harmonically richer than a push-pull OTL amp is that the latter has a phase splitter that causes information to be lost?
After all, when we speak of 'SET vs OTL', what we mean is single-ended transformer-coupled vs. push-pull direct-coupled.
Ralph, I like your amps and have a lot of respect for you & your company, but to say that the <1% of 2nd-order harmonic added by a SET at moderate volumes on appropriate speakers, when studies have shown up to three times that amount is not audible, just doesn't make sense to me.
A good SET just gives me more 'chills of realism' than an OTL push-pull amp.
Mind you, I'm no musician and don't have perfect pitch. |
I meant to say "but to say that the <1% of 2nd-order harmonic added by a SET at moderate volumes on appropriate speakers *is what causes this harmonic richness*, when studies have shown up to three times that amount is not audible, just doesn't make sense to me." |
Larryi,
First of all I acknowledge that this is something of a matter of taste and also system-matching - as you pointed out, a ripe, bloomy mid-bass *can* be an attraction!
It isn't in the systems I've put together.
EML makes very good tubes but their 300B retains the tube's bass characteristics IME. They may go somewhat lower than most but it is not an tight & controlled, nor as linear in the midbass region, as the 45 - especially the EML 45.
Not sure if you heard an HE version of the AN/E but if not you're talking about 3 dB lower - right about the power difference of SET vs push-pull.
What were the PP 45s you heard? |
Aarif,
It is true that there are studies indicating that a 'natural spectrum' of harmonics - which includes even-ordered components - sounds better/more natural to our sound processing systems (brains) than the same signal with only the odd-ordered components - despite the fact that THD is obviously higher in the former case.
Re: "As for SETs, the problem is (correct me pls) that even order dynamics can be accentuated by the tube's interaction with the transformer, making the sound more lush/"pleasing" but less natural/neutral." I've never heard that.
I would say that good SETs on the appropriate speakers do *not* sound 'lush' - ever. They sound crystal-clear, just right, completely natural, etc. That's how a 45 sounds, for example. Or a good 211. Other tubes probably do have some intrinsic 'character'.
Of course, good push-pull OTL tube amps sound a lot like that too. They sound even leaner, or 'whitish', as I would describe it.
What's closer to reality might be impossible to say. |
Martykl, if there is one maker of SETs that could be called LUSH, it's Cary. Even their 2A3s are lush, which I'd have thought impossible to do.
You're description of SET bass is especially off in regards to the 45, by the way: very, very tight low end, NO exaggerated mid-bass at all. In fact, they're rather like Ralph's OTLs in that aspect.
No triode is as clear and direct as the 45 IME. I may have mentioned the 211 in the same breath - it's still not nearly as see-through - not in amps I have experience with anyway. (Ongaku? Maybe. Cary? Even less than the Consonance 211s I owned.)
Like you said, 'lush' is not necessarily bad.
Ralph, I didn't realize your OTLs have only one gain stage. I learned something. I may need to try one again. |
Ralph,
Yes, there are studies that show even-ordered harmonics as musically consonant, but I do believe some of them or other also showed lower amounts - like 3% - to be inaudible.
It is very easy to keep THD down well, well below 3% - more like .1% or better - with copasetic speakers at moderate volumes. That's why I can't accept that the differences in HD spectra explain *everything* about why single-ended sounds different than push-pull.
As for the number of gain stages, most low-power SETs have one plus the output stage - just like your amps - right? I'm quite admittedly not an engineer but your OTLs do have two stages of gain counting the output tubes, right?
As for the lack of a phase splitter, that sounds like a plus, but please tell me, does crossover distortion still exist? I've always thought another of the big benefits of single-ended operation is that there is (obviously) no such thing as crossover distortion - because there's no 'crossover' - and distortion is *proportional to power output*.
Push-pull amps, all of them if I'm not mistaken, do suffer from the fact that crossover distortion is *inversely* proportionate to power, meaning the tiniest nuances are lost.
Not that your amps sound like they are missing nuance - they don't.
They also, incidentally, have some of the best low-bass control I've ever heard, even on 4 ohm speakers - an OTL myth shattered. |
Martykl, no properly built single-ended 45 amp is lush in any sense into appropriate speakers.
Have you heard any? Which do you call lush? |
I agree with Bill's ordering of the triodes except that I've never heard a 50.
300B can be done well (I learned recently I really like the JE Labs 76/6SN7/300B circuit) but bad implementations outnumber the good, it seems! The thickened midbass and blunted transients is a show-stopping for me.
I'd also throw the PX-4 in there either before or after the the -25. I had a Kurashima PX-4 - amazing amp.
People always talk about how much difference the circuit, driver, power supply, and output tranny make, yes the various tubes almost always retain their basic sonic character no matter what the amp IME.
However, I've heard those Wyetechs really break the 300B mold. I've also heard that about the Welborne DRD circuit.
As for volume and dynamics, yes, for a 45, you need a back horn, front horn setup, or highly efficient widebander on OB. But it's amazing how dynamic the good SETs are within their capabilities.
Any decent 300B SET will drive 90 dB/W dynamic speakers that are a fairly easy load very well. I'm thinking DeVore, Green Mountain.. lots of others. |
Martykl,
You really can't ask a question like that without specifying your desired loudness level. 80 dB vs 100 dB - 10x the power!
I recently spent some time driving the 90 dB/W DeVore Super 8 with a pair of 45 monoblocks. I tried it at first just as an experiment, and I discovered, with listening levels of 80 dB on peaks in my large room, the (jazz) bass lines were incredibly articulate - perfectly sculpted. *Much* better than the 300B monos I'd just been using.
Is this a recommendable real-world combo? No, of course not - not unless you listen pretty quietly! My point is that, despite the inappropriate pairing, I could still evaluate the bass of these two sets of amps - and, in both cases, it had exactly the characteristics I have come to expect from these two output tubes. (And, while, again, not recommended, this combo was so good I left it setup this way for weeks. I'm trying to train myself to like lower SPLs anyway - and with this setup I could.)
If you want examples of speakers that can be driven cleanly and dynamically to moderately loud levels with a 45 SET amp, and have bass flat to close to 20 Hz, I can give you two: HE versions of Audio Note AN/Es and Supravox field coils on open baffle. The latter supported by powered subs (TBI) below 50 Hz.
If you want LOUD levels, I think you have to go to front horns and/or speakers with powered bass modules (Zu, others). |
Typo - of course I meant 100x the power required from 80 dB to 100. |
Now, I happen to like JohnK, and some people do prefer the 300B. I never quite have - but they do have their own strengths and can sound very nice (of course).
Surely they have the ability to drive well speakers that 45s can't hope to.
[I meant to point out that my TBI subs are driven from high-level (amp) outputs, meaning I am hearing the bass signal produced by the amp, not the preamp.] |
Martykl,
If you use a powered sub but with high-level inputs - as many people believe is preferable - the bass characteristics of the amp still matter - except for power (current) delivery.
Yes, the HE AN/Es work very well and really do give usable bass to 20 Hz positioned in corners as designed - flat to 30. (I'd say peaks to no more than 85-88 dB in a large room, however. Small room, obviously louder is possible. But AN/Es tend to overload very small rooms with bass.)
I know for certain there are people who have used Zu Definitions with 45 amps with very good results. Those have powered bass, good to close to 20 Hz I do believe. |
I know someone who says those PP DevaVu 45s are the best amps ever made. |
