What is it about SET amps?

[George Roland]

Hi,

I have no electronics background so a very technical explanation is not necessary. But I am wondering what it is about SET amps that makes them such a good match with Klipschorns and other very high efficiency speakers?

I have an idea of the conditions amps are up against driving very inefficient speakers, and can understand that an amp designed for high power to drive such speakers might not be suitable for ultra-efficient speakers like K-horns.

But, turning that around, what is it that makes SET amps, sound good? I know little wattage is required for very efficient speakers to produce high sound pressure levels, but what does that allow the amp to do better?

Are good SET amps inherently highly detailed for example--revealing more information form the source? Is part of the answer just the relative simplicity of the circuitry?

Thanks,

George

[edwinr]

Hi George. I've driven my Klipschorns with 200 plus watts per channel and they loved it . So did I! As you go lower down the power output scale, say below 20 watts per channel, it becomes more crucial to carefully match your amplifier and loudspeaker combination with your room size and listening levels. Very low powered amplifiers obviously place restrictions on listening levels and the choice of music. Leaving amplifier topology aside, I view with some sceptism any claims that a 1.5 watt per channel amplifier can properly drive Klipschorns to reproduce the kind of dynamics they are capable of.

[George Roland]

Okay,

Now Mike has made a claim for the linearity of SETs and your argument for higher power is related to developing adequate dynamics in the sound reproduction. So doea that mean that higher powered amps that produce, presumabley a wider dynamic range are less linear?

Also how do dynamics and linearity play into the situation I am most curious about that I would call resolving power, that is the ability to reveal the maximum amount of inner detail with an open uncompressed sound? I must admit to being strongly attracted to a system's ability to reveal threads of every instrument in the ensemble...each instrument's timbre accurately shown so a clarinet, oboe, flute can easily be identified and distinguished in complex passages. Would SETs be better at this, and if so, why?

George

[Coytee]

I view with some sceptism any claims that a 1.5 watt per channel amplifier can properly drive Klipschorns to reproduce the kind of dynamics they are capable of.

I wholeheartedly agree with you however, I don't recall ever hearing anyone make that suggestion? (that a 1.5 watt, or a 50 watt amp can drive Khorns to the kind of dynamics they are "capable" of) ???? (maybe I'm being overly anal.... [])

I've had mine on 4 wpc (bridged SE-OTL's) and they sounded utterly fantastic!!!

I've had them on SS amps, similar in power to yours and they soudned utterly fantastic!!!

Kind of like Dr. Jekyl & Mr. Hyde....

The SE-OTL's had a sound about them that though not terribly loud, was "right". I was terribly frustrated with them (the amps) because I wanted to turn THAT sound up and they simply didn't have the oomph that I so dearly love.

[]

[edwinr]

It is interesting that many of the worlds best preamps feature SET operation. I would not dare to argue with Mark that this mode of operation is a nearly perfect amplifying device.

I also find it interesting that SET's are used in power amplifiers. SET fanciers promote the low power operation of some of these power amplifiers as a feature, not as a drawback. I will state quite clearly here, that ANY low powered amplifier, regardless of the topology, will never have the dynamic ability of a higher powered one.

Why do some have difficulty in understanding this? [8-)]

[jbsl]

"SET fanciers promote the low power operation of some of these power amplifiers as a feature, not as a drawback"

To SET fans it is a feature they prefer not a drawback.

For you it is a drawback because you prefer "the dynamic ability of a higher powered" amp.

I used to have a pair of SET 2A3 Moondogs 3.5 watts and I have a Cayin TA 30 tube amp 35 watts.

The 3.5 watt Moondogs could equal the dynamic ability of the Cayin in my living room at the sound levels I listened at.

Don't misunderstand me the Cayin unquestionably had the higher dynamic ability of the two amps. The thing is I never usemore than 4-6 watts(my guess after comparing the Cayin to the 3.5 watt Moondogs) so for me the higher dynamic ability of the Cayin is useless until I move into a much bigger living room. The extra 30 watts is a feature of the amp that I do not use because in my small living room it over powers the room.

Here is the review I did on the Moondogs and why SET amps might be right for some people but are not right for everyone.

http://forums.klipsch.com/forums/thread/758200.aspx

There is no wrong or right in this game only what makes each individual happy. What works for you may not for me.

ENJOY[|-)] the TURKEY!

[Duke Spinner]

aaaaahh ....

you may have only been using 4 continious watt's.....

but your Power Supply was drained at that level ( yes, Dan, i know , not All SET's )..

and here comes that 25 dB peak..!!!!!!!!!!

now, I know my 500 wpc Crown's got the A$$ for that peak ....

howsabout SET..??

[Al Klappenberger]

Guys,

Here's my chance to "mouth off":

1-SET amps have one tube and should be real cheap - they aren't. RIP OFF!

2-SET amps generally only have about 5 Watts. No head room at all! RIP OFF

3-SET amps operate class A and draw a lot of ideling current continuously making a lot of heat. That's why they are usually only 5 W or so - RIP OFF

4-SET amps depend on operation at low levels because a single tube goes non-linear as the levels increase - That's is, they are distortion generators when you turn the volume up a bit - RIP OFF.

5-SET amps usually don't have any negative feedback. This causes them to have high output impedance (poor damping factor) and are very sensitive to the inconsistant loads that Klipsch loudspeaker shows them. - RIP OFF

In ll fairness, they do have one advantage that may be why people like them. At low levels they do not have the distortion that a poorly desinged SS amp will have becasue of such things a notch distortion. A good quality push-pull amp no matter if it's tube or SS will not have that problem.

If you want a tube amp, get a good used push-pull one like a Marantz 8B or McIntosh MC275 and be prepaired to pay THOUSANDS! If you want a new one, Graig of NOSValves makes a good one.

Al K.

[Daddy Dee]

Mark,

Thanks for the SET tutorial today. Interesting stuff, and some new material for the knowledge base, in my mind, anyway.

[colterphoto1]

First thread about SET that I actually understood. Thanks for explaining it in simple English. Is the SET tube those big bubbled-out looking ones or how do they differ from the other tube types ? (just so I can get a picture of them in my head)

Michael

[Erik Mandaville]

"Leaving amplifier topology aside, I view with some sceptism any claims that a 1.5 watt per channel amplifier can properly drive Klipschorns to reproduce the kind of dynamics they are capable of."

And I say with complete lucidity that there are two 1.5 watt amps that are among the best sounding amps I've heard with Klipschorns.[]

Erik

[Cut-Throat]

All of the above points about SET amps may or may not be valid.

The reason I listen to SET amps is that they sound better!

[seti]

I never considered my 8WPC Canary Audio SET amps to be low power : ) I will have some of those high power 211 or 845 based SET amps some day.

If you are in the market for a SET amp make sure the iron is of top quality. If they are cheap irons it will sound like a cheap toy.

[Coytee]

"Leaving amplifier topology aside, I view with some sceptism any claims that a 1.5 watt per channel amplifier can properly drive Klipschorns to reproduce the kind of dynamics they are capable of."

And I say with complete lucidity that there are two 1.5 watt amps that are among the best sounding amps I've heard with Klipschorns.[]

Erik

Ahhh....Grasshopper... You know I'm in agreement with you on those two 1.5 watt amps [{] [}] however, are you saying that those two amps, even if bridged, will reproduce the kind of dynamics the Khorns "are capable of"?

Me thinks the original statement is phrased such that the answer has to be no, is it not?

Being among the best SOUNDING, woudn't dictate extracting the 'most dynamics' the Khorns are capable of, does it, regardless of how great they sound?

and those two wimpy amps ARE absolutely delicious sounding. Oh, how I long for them to be on steroids....

[]

[coda]

if there was an easier way to measure what is perceived as retaining the integrity of the original audio signal, as well as linearity, perhaps we could all be talking the same language when it comes to sound.

The Single-Ended Amplifier: Cary's Dennis Had

Robert Harley, September, 1995

Cary

Audio Design founder Dennis Had is largely responsible for popularizing

single-ended amplifiers in America. Since appearing on the scene in

1989, Cary Audio Design has forged its own niche in the high-end audio

industry. I spoke with Dennis Had about how he got started building

amplifiers, and why he's so committed to single-ended triode designs.

Dennis Had: It

all started with a science project I did as a child, which was a

single-ended audio amplifier. It was based on a 2A3 [tube] and had all

of a couple of watts. It got the blue ribbon, and I was hooked forever.

After that I became intrigued by ham radio. I built some

shortwave radios, and had a ham radio license when I was 11. There was

a group of us into ham radio and audio. My buddies were building higher

and higher output-power amplifiers, and the mentality was that the more

power the amplifier had, the better it must sound.

I was going

in the opposite direction, trying to replicate the sound of my father's

string quartet, which practiced every Friday night in our home. I knew

what real music sounded like from hearing that string quartet every

week. My objective was to re-create that electronically. I would play

back the records they made and try to replicate as closely as I could

the sound of the string quartet in our home.

Every time I

worked with a single-ended triode instead of a push-pull design it

sounded more realistic. Running single-ended, it seemed that the

speaker was less prevalent and the sound was fuller and more lifelike.

I remember saving my paper-route money and spending $9.90 for a 300B

[output tube], because that was the next step up from a 2A3. My friends

were buying 6L6es at 59 a pop, and I'm spending nearly $10 on a 300B.

They thought I'd flipped my lid. Their amplifiers were more powerful,

but mine sounded more realistic. I still have that first 300B. It has a

gazillion hours on it, and it still functions beautifully.

Harley: Was your career in RF design an outgrowth of your experience as a teenager?

Had: My

formal career was as an investment banker. A lot of what I did was

secure investment funding for companies. I had some ideas to start a

company in the RF field, which I knew very well from an engineering

standpoint. In 1974, I designed an RF receiving and transmitting

converter and founded a company on that design. In 1978, we were number

82 on the list of fastest-growing privately held companies in America.

We went from my basement to an industrial park and 70 employees. It was

extremely successful.

I was way ahead of the leveraged buy-out

boom of the 1980s and in 1978 did a leveraged buy-out of another

company. By 1980 I got killed. I sold the whole thing.

But all

along the way I was building very sophisticated high-powered audio

amplifiers for my own enjoyment. In fact, I had a 300W single-ended

amplifier. In my neighborhood, if you wanted to listen to music, you

came over to the Had house. I always had this love for audio

amplifiers. I didn't know what it was to go out and buy something: I

built everything myself.

Harley: What made you go into business building amplifiers for other people?

Had: I

started another successful company in 1980 designing and building RF

products, and I sold it in 1983. I did some RF design for other people,

all the while building audio amplifiers for fun. Then I walked into a

new high-end store right here in Cary, North Carolina, and I saw tubed

amplifiersbrand-new tubed amplifiers! I was shocked. I knew

about Audio Research but never guessed at how popular tubed amplifiers

were. I got to know the store owner and bought an amplifier to see what

made it tick. I thought it was an accident waiting to happen.

The store owner asked me to work on some of the tubed amps he had in

for repair. When I took the stuff home, I saw the shortcomings of each

one and knew I could build a better product than what was being offered

in the marketplace. At the same time, it would give me an opportunity

to present what I considered to be the best-sounding amplifier design:

single-ended.

Harley: Wasn't it commercially risky to

start a company based on an older, low-powered technology when

single-ended amplifiers were virtually unknown in the US in 1989?

Had: You

ask yourself which is the greater risk: to build "me-too" products and

come into the marketplace against established companies, or to have a

product that is totally dissimilar from the run of the mill, one that

would stand out because of its unusualness.

Of course, I took

the second option. I would rather be recognized for having a different

type of product than a copycat product. There were so many people using

the same mundane circuit over and over again and just repackaging it. I

thought it was better to offer a technology that I personally believed

in and was different in the market.

Harley: How do you respond to the question of the poor bench performance of single-ended amplifiers?

Had: You

can sometimes fool the marketplace with good-looking test results. But

every time I try to make a single-ended design look beautiful on the

test equipment, it takes the beauty out of the musical presentation.

It's a whole different ballgame between specs and what it sounds like.

With single-ended, the lack of feedback, the simplicity of design, and

not splitting the signal are more important than test results. Forget

about the total harmonic distortion: any of the nasties that may be

there are masked by the second harmonic, which isn't offensive to the

ear.

Harley: What are the virtues of single-ended?

Had: More

than anything, the virtue of single-ended is the simplicity, and that

the signal is handled in as linear a fashion as possible. In a

push-pull amplifier you split the signal into two halves and then

recombine those halves at the amplifier output. I felt that the power

amplifier should just replicate what the CD player or turntable is

outputting and maintain the integrity of the waveform. Single-ended

makes the most common sense from an engineering standpoint and also has

the least number of parts in the signal path. You're not taking the

signal and dividing it up.

Another key factor is lack of feedback. Feedback is always a correction after

the fact. I'll often take apart competitors' amplifiers and remove the

feedback. After doing that to many designs, I've found that the

feedback is just a big Band-Aid trying to rectify what should have been

done right in the first place.

My commitment to single-ended comes from my personal beliefs and designing and listening for the past 38 years.

[George Roland]

Thanks, Mark, for reading carefully my original posting and responding to it.

I have no partisan axe to grind one way or the other here. I have a 100 wpc tube amp (ARC VT-100) and a 100 wpc solid state amp (Hafler 220) I can listen to. Whatever strengths or weaknesses these amps may have, they can provide me with dynamics.

I have never heard a SET amp and know many members here, whose opinions I respect, who listen to and love them. I listen almost exclusively to acoustic music. Classical music, symphonic music and opera as well as folk music, acoustic blues, some rock but not at ear-splitting levels, and Mark got it right...I'm maybe willing to sacrifice some dynamics for inner detail, clarity, timbral accuracy and so on.

It seems that, as I read these fascinating postings, that the linearity of SETs, and lack of feedback may give them the edge in those areas over high powered amps that are more dynamic.

Maybe we agree that a 5 wpc SET isn't going to be able to best a 100 wpc amp for dynamics or ultimate volume?

Mark read my post and recognized that is it the quality of the sound I am seeking responses to. Surely dynamics are important but not the only criteria.

I'm wondering now from those of you who have experience with both types of amps, SETs and high powered, very dynamic amps, if you could comment on the relative strengths of these types of amps in the areas of timbral accuracy, layer upon layer of detail and clarity?

[edwinr]

Great posts in this thread. Whilst the content is questionable, they are well written.

Can I leave spl's out of the equation? Let's just talk about our need to resolve fine detail.

I argue that for accurate reproduction of this 'fine detail' for want of a better phrase, requires an amplifier with the ability to reproduce dynamics. If a single note is struck or played, there are all sorts of things going on soundwise so that we end up with what we have heard. As we all know, a single note played on a piano is made up of lots of components. I want this note to be reproduced as accurately as possible. I also want all the other notes that accompany the first note, which of course makes up a melody, to be reproduced accurately as well.

You cannot separate my desire for accurate dynamics from the need for inner detail, clarity and timbral accuracy. Like one of my wonderful lamb casseroles, you need every ingredient for full flavor. If you leave out an ingredient, you still have lamb casserole, it's just not as tasty.

Low powered amplifiers, and here we're talking SET power amps at the moment - I guess - just cannot reproduce a musical note as accurately as a more powerful amp at normal listening levels. This is given similar moderate spl's in a moderately large room like mine. The lower powered SET amps that I have heard DO sound wonderful, but not accurate. They tend to diminish or compress the micro and macro dynamics of music. This gives the impression of inner detail because there is not much else going on around each note. The brain is easily fooled.

A low powered SET amplifier can only offer a smaller window into the reproduction of music. Just have a careful listen, preferably side by side with a decent amplifier with decent bandwidth and adequate power reserves. It's not black magic or hype. You can hear this.

[mike stehr]

"I do think they get a weird rap here on Klipsch because 90% of the posters here place almost all their emphasis on loudness and bass and dynamics."

Yup.....

[rigma]

edwiner said "A low powered SET amplifier can only offer a smaller window into the
reproduction of music. Just have a careful listen, preferably side by
side with a decent amplifier with decent bandwidth and adequate power
reserves. It's not black magic or hype. You can hear this."

I have and totally disagree, my 300B's are here to stay!

[Daddy Dee]

you've got that right