SET the best?

Is SET amplification where we should all end up? I keep reading posts where people tell of their journeys from plenty power to micro power, and how amazing SET amplification is 45 set 211 set 845 set otl, and usually, ....with the right speaker. I have yet to read of anyone who has gone the other direction from SET, to High watt beast class A amps or others.
If your speakers can be driven by minimal wattage, is this the most realistic, natural sound we can achieve? versus say, 86db sensitive speakers and a 1000w amp?
Is the end result solely based on speaker pairing? circuit? tubes?

I am in the process of changing my direction in my search for realistic sound, just because, and wondering if this really is the best direction to be going.
From what I have been reading I think it may be.

What do we get with SET? What do we give up?

What's you favorite color?
Its a personal taste. What a good SET can do is present a wonderful listening experience from a low power perspective. In no way, shape, or form can it be better or worse than other configurations. You don't need to break the bank to find this out either.
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Have gone from 350 watts to 2 watts. Considering 500 watt mono's but for my HT.

Speaker paring is critical if you want to maintain dynamics etc. I feel horn speakers are better suited for SET. System matching is also important & easy to get it wrong having all the right componenets.

What you would mostly give up is the lower end. Can be remedied easily with a fast subwoofer like REL. what you get back is ++ mids, musicality.

My system prior to going SET (which I still own in HT mode) did bass extremly well. 18Hz - 20Khz transmisson lines. Somehow I don't miss this.

All tubes you mention including the 2A3 has a different flavour.I guess finally it come down to personal choice. Current flavour 2A3 & going for 45. Try it. If this is not your sound you can always go back.

For me it's SET without a doubt!
I like SET but you will never resolve this with a post here on Agon because too many disagree. You can not get people to agree on SS or tube as the best let alone SET tubes which can have limited bass control (compared to SS especially) and only drive a handful of speakers.
...i have a goldmund 29m amp..solid state which is superb...saying that...if you have had the opportunity to hear what a truely great SET sounds like, in my opinion , there is a naturalness to the sound that is addicting. the downside of most SETs is that they don't perform well with real world speakers with difficult loads or ones that are insensitive which limits the choices for those who like SETs.for a price..there are a handfull, or less, that can drive alot of the speakers that here-to-for could only be driven by solid state amps.the chalice audio ' grail' amps are in that 'handfull' catagory and are the best amps i have ever heard...but are also very expensive...but thats relative.!
1. you have a great system 2. never build a system around an amplifier (a carwreck) stereo plays every record or cd perfectly....and it never is 'like' live music, good or bad.
Favorite WE 300b

Second favorite Russian

Favorite beach...easy, just outside of Hanalei

Mike, as mentioned in the posts above there are some really cost-efficent ways to try out SET amplification. Visit 6moons for a few reads on the different flavors that are available. From there you will be off chasing speaker designs that are efficent along with easy loads to drive. SETs just love easy blowing trade winds...
It is a matter of taste. I was a high current SS guy for many years and morphed into SET once I heard a nice sounds very natural and I found myself listening to the music rather than the equipment. Downside is tubes require a little bit of fussing and you are limited in your speaker choices. However, there are a lot of highly efficient speakers out there and if you are a "fiddler" then you enjoy biasing tubes, swapping out tubes to try different sound combos etc. I have a second rig for my tv and it's high powered SS.....yes it's more visceral but the highs are a little etched and it sounds a little artificial but still a good rig....I just can't listen to it for hours on end without some fatigue creeping in.

And while there are a few nice beaches out near Hanalei (especially the one with the wicked rip), I like Anahola beaches better (sorry hanaleimike), but I won't say which one because it isn't very crowded.

I also really like Polihale.
I had the Cary CAD300SEI. It sounded very good in my bedroom system.
I got a pair of small floor standing Meadowlark speakers,
with the Vifa Ring Tweeter. They sounded very good with the Cary. They sounded even better driven by my Pass Aleph 30. That speaker & the Pass solid state amp just worked better.
I'm suggesting you should try to pick your favorite (affordable) speaker first, then try different amplification.
When you get that combination with a synergy in your system, you'll have the answer that's unique for you, your gear and your room.
My favorite color is blue. The Cary branded 300Bs in my CAD300SEI had a blue glow to them. They sure looked cool!

The beach on the other side of Cozumel

SET...tried it, didn't like it.
I have yet to read of anyone who has gone the other direction from SET, to High watt beast class A amps or others.

I DID go the other direction. More on that later. SET does some unique things that few others can do quite so well. Really good OTL actually has some of these qualities and ads some of its own. Nothing seems to get the living breathing palpable human presence like a great SET rig, at least not without spending a year's sallary or more. That presence is haunting in a great SET rig. What it traditionally does not do as well at is the extremes of frequency extension. It's all about the midrange presence and holographic presentation in space. It is addictive if you really appreciate those qualities. One other thing it is not good at is complex, layered music like orchestral or hard rock. Advocates will argue that they enjoy those genres on their SET rigs, as did I on occasion. I would respond that they are much better served by other topologies. I got hooked on SET and remained hooked for just over six years. Other amps came and went, but my Quicksilver 300B SET amps stayed. I found that haunting 'presence' they offered to be addictive. They did meet their match, no, that's not right...I found something that did everything so well, with such balance and finesse, including presenting a palpable holographic stage, albeit not the rival of SET, but with so much more all-round performance while not giving up too much (much more so than anything else I'd heard with the only exception being perhaps Atma-Sphere OTL amps which also sound very compelling to me offering much of what SET has to offer along with the frequency extension they lack). The amps that de-throned my SET amps were Modwright KWA 150 amps. I never thought I'd have a SS amp again as they'd never really grabbed me enough to even consider one, but this just does not sound like any SS amp I've heard. Disclaimer: Dan is a client of mine. Make of that what you will, but I sold my 300b's to afford the KWA. The KWA sound definitely gives a knod to tubes, but I would not define it as "tube-like". It also has SS qualities in spades, especially in grabbing the low end by the barnacles and not letting go, yet it does not sound like SS either. I'd mostly been drawn to tube amps and have owned many over the years, as well as having enjoyed others in close friend's systems. The only other SS amp I'd heard that would have me consider owning it was an Ayre. Mind you, no SS amp I've heard can do what SET can do quite as well, but SET has a fairly narrow appeal in terms of what it does well, and what music it suits best (IMO - again, advocates may argue but that's been my experience). To the OP's question - it's certainly a path I'd look into if you are after very natural, palpable presence, but do be aware of its limitations. Is it the path we should all end up at - absolutely not. I can imagine there are many people who would not appreciate what SET has to offer and would choose other qualities. There is no path we should all end up at. The choices are infinite. So many amps, so little time.
SET is best if you have the speakers for it.
Thanks for the responses gentlemen.
I have owned many tube components, including 2 amplifiers ( ya WOW, I know ), and currently have a Cary slp-98 and an EAR 834P, I like tubes ( I haven't updated my system photos for a while )
The only reason I replaced my Cary sli-80 was that a McIntosh mc2500 was dropped in my lap and it sounded much better with my then speakers, the Spendor sp1/2e's.
I am currently trying to acquire a pair of Audio Note AN-e/spe's ( possibly the ones Jax2 was going to look at ?) Of course I will try them with my mac, but I don't see this pairing come up too often in my searches.
I am a fiddler of oc proportions. I love/hate rolling tubes, I move my speakers way more often then necessary ( the floor around my speakers looks like it has been shot with a shotgun ) , build my own stands, then change and rebuilt them, and have everything on some type of isolation thingy. I love fussing.
I don't often listen to loud stadium rock, or large orchestral music. I am looking to trick my brain in the most believable, extreme manor.
The an-e's go down to 20hz, so hopefully I won't be losing any bass. I have been considering the Transcendent set otl 1.5w amp currently for sale which I have been told has very deep and tight bass along with all the other desirable SET qualities.
Sounds like I am a candidate for a SET amp. Thanks for your time.
Yes, from your latest input, Hanaleimike, I would definitely recommend giving it a try. Should be a great match with AudioNote speakers. OTL is definitely is worth pursuing as well - it will give you very similar qualities, albeit different in both subtle, and not so subtle ways. All SET are not created equal either. Various tubes render different characters alltogether. Definitely look for substantial power supplies as this will make a significant difference in my experience. The one common theme I'd say is that the emphasis seems to always come out as midrangecentric and creating a holographic illusion (at best). The real flea-powered SET stuff really just focuses all its energies on midrange and is entirely a one-trick pony in my experience. But that trick is pretty damn good. Parallel SET is also worth consideration, as is push-pull triode. Those AU15's Grant is using are great amps. There's currently a pair of Wright Mono 10's that are quite similar, but not quite as good, at a bargain price here if you are looking in that ballpark. If you have greater funds, and or need better-looking casework, look elsewhere.
Thanks, I will research them. Does anyone know if the McIntosh MC2500 is class A?
No, the 2500's are not Class A.
I went from 3.5 watt 2a3 SET monoblock amps made by George Wright and his very fine preamp plus a very nice set of IM Ben speakers made by Terry Cain. These were large folded horns, single driver speakers. Also paired the Cain & Cain sub with the Cain & Cain Ben's.

Liked the sound as I wanted a nice engaging and warm sound. The kind that just draws you into the music without a hint of glare, brightness, aggressiveness or listener fatigue. Got all that, but in the end I missed those times when I really wanted to hear and feel the impact of live music. This set up was awesome but lacked the scale and impact I also like. It was good for a year, but I had to find what I missed and not give up that wonderful warm and intimate sound.

My quest over the last 3 years was to do this. I have never liked most of today's hyper detailed speakers and wire. As an example today's Dali speakers (800's) can't hold a candle to the older and discontinued Dali Grand that can be found for $1500 or so used. Sure they soar higher and give more detail, but I wanted to leave the room in 10 minutes. Warmth, body and musicality is what I want with effortless power and dynamics when called for.

Found the same with wire. Most highly touted wire is to front row and detailed for me. Give me that cable that some call boring and just kind of "there".

For me, I found I did not have to settle for SET and the limitations it had for me. Others don't find my so called SET limitations limiting and I respect that for them.

I ended up with the following and have the best of both worlds. It has taken lots of time and effort. The key was getting the right speaker. The Silverline Bolero is a refined speaker that does not force you to "take notice of me I'm a loudspeaker". Great warmth and depth with glorious body. Stage is set back and they throw a huge stage. They can handle 1000 watts when called for and sound so effortless.

I like using a first rate tube pre and SS amps. I got both from TRL, Tube Research Labs. Amazingly musical pieces.

I desire wire that has warth and body. I like gold and copper in the IC's. I like Acrolink power cables as they are warm and full bodied. I like KCI Silkworm and Audio Horizons Dimension IC's.

With proper system matching and the right gear I think you can have the best of both worlds. Large scale, impact in your chest experience and wonderful, warm intimate music.

If you want to travel the SET route it is fun to be sure. The experience is something you really must go through to understand the SET thing for yourself. For some, unless they experience it they will always wonder. That is me!
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I was one of the pioneering voices of the SET movement and as I grew with the hobby I discovered that as good as SET amplifiers are, there are not as many good loudspeakers to complete the chain. Having heard well set up-up Wilsons, Magicos and owning MBL 101Es I can honestly say that the speaker is t-h-e most important variable in a high end system. SET is incomparable if you have uber expensive amplifiers mated with loudspeakers that you (can) allow to have certain faults; like lack of LF or lack of dynamics, or lack of finesse. There is no magic bullet speaker for SET. On the other hand, great speakers like MBLs and numerous others allow for many different amplifiers and combos that you can tailor to your taste. In SET land the dog's tail is wagging the dog-- with great speakers and higher powered amps the dog is wagging the tail. I've lived it, reviewed it, and promoted it and it's just the way it is. Some may say that you can cheat physics with big Wilsons and low powered Lamms but a question mark hangs over my head with these set ups. I think that you may be shortchanging both products and ending up with neither fish nor foul.

A great SET systen is very satisfying, with hints of human realism, almost stylisticly so. A great Wilson, Rockport MBL, Magico (fill in the blank) system is like being at a concert, though matching ancillary equipment is very demanding. Both are fun, but only one is like being there.

Count me in for "Yes" stats.

Went planar, electrostatic, vintage, single driver, with both SS and tube amps not less than 30 watts and speakers as high as 94 dB efficiency. I was happy but still something was missing I thought per my preferrence.

I found my heaven on both DIY flea powered SET/High efficiency coaxial speaker(100dB) with a simple topology active preamp and so far still enjoying it. To me, speakers should be at least 97 dB and above, the higher the better. Power not more than 6 watts (I will not be surprised if I am oly using less than a watt on normal listening level. If it doesn't sound good at 1 watt, why need more?). Also, I found my preferrence on using DHT tubes with AC on the heaters for output tubes of the amp and old type DHT/IDHT tubes (currently using 76) on the preamp side.

To me, although it is hard for me to describe it, there is something about speakers with 98 dB and above efficiency, full range, using 45/2A3 tubes with AC on the filaments that 96 dB and below speakers cannot touch. But the trick is to make the amps quiet so that hum will not be an issue.

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It depends. Believe it or not, Johnatan Swift described a detailed answer to your question in his "Adventures of Hulliver in the Country of Lilliputs"...
I still own my Cary 300B monos and my Cary 805 monos, but the speakers I'm using at the moment (Ohm 100s) won't play nicely with either of these amps. Right now, I prefer the Ohm/ARC VT130SE combo to anything I can hang off of either Cary. So, SETs can be great, but you've got to find a suitable speaker you love.

I've been a SET convert for about a decade. I have no desire to go back to Solid State. While the limitations of SET are well known (low end frequency can't match SS, Need efficient speakers) I think their strengths (mid range magic, unbelievable presence, non-fatiguing sound) are worth any inconvenience. I have 3 SET amps (300B, 2A3, 45) and they each have their own special sound. I love using the 300B with Orchestral or more complex music, 2A3 with Jazz, and 45 with chamber music or simple vocals. SET amps are also very sensitive to tube changes so you can fiddle to your heart's content in tailoring the sound to your liking. I think everyone who loves audio should try SET out at least once. It's like a rite of passage.
Breuninger, Wow! My sentiments exactly. Well said.
I use SET PP SS designs tried most everything. I enjoy good SS and SET amplifiers but for SET get the right loudspeakers or not so nice. With the right designed loudspeaker a SET can produce deep detailed bass much SPL with low distortion. But loudspeaker will not be small. Still most all systems have limits and a fullrange driver plus SET can be very enjoyable and still have fidelity, not all about colorations and distortions like many say but acurate and detailed as any SS based system. Still for SET best to have loudspeaker designed for power output of amp a 45 SET does not drive loudspeakers as well as hi-power SET;) And will need more care with loudspeaker matching, most 300b set can drive vintage designs and allows more options with loudspeaker choice. 45 SET can sound wonderful but not if loudspeakers not matched. One should always look at audio as a system and SET owners need even more thought to total system matching than most other amp designs.
Johnk ;
I realize you probably don't want to blow your own 'horn' here , so can you enlighten us on the qualities that we should look for in a speaker for SET use ? Particularly refering to the bass issue that you eluded to . We also would be interested in the issue of complicated music refered to above .
It would be helpful if you could go beyond the afore mentioned high db. rating and flat high impedence curve .

You may pm me or ask for a more approprite thread on the speaker page .

Thank you.
Saki70, the speaker should be designed for tubes. See

for more information.

I spent a few months tinkering with some 45-based SETs that I inherited last year. In analyzing the circuit, I realized some performance gains were possible through some simple mods and so got the amps to sound a lot better. Ultimately though I got curious what would happen if I made a P-P 45-based amp and did that as well (it makes about 4 watts and is class A). It was **instantly** better on the first attempt. IMO/IME most P-P amps are too complex and if a minimalist approach is taken SETs will not compete.
Hi Ralph,
I'm going to acknowledge, before I even ask, that this question is likely an example wrongful thinking.

Many people use tubes with speakers that were probably not designed with tubes in mind - in my case JM Lab Mini Utopias. My question is: Can a modification be done, perhaps to the crossover, that would result in the amp seeing a friendlier impedance curve?
For clarity, I'm asking about speaker mods only.
Phaelon, SETs are usually not very powerful. A big one is 15 watts, maybe 20. If you really want to hear what they do, the speaker has to be efficient enough that you never bring the amp anywhere near full power.

At full power, the THD is often about 10%! At low power levels, the distortion might be unmeasurable, and what of it there is will usually be lower orders (2nd, 3rd and 4th). At high power the high orders become involved- that is the range of the amp that tells you not to turn the volume up any higher- it *sounds* loud due to to the presence of the 5th and 7th harmonics, which tell the brain how loud the sound is.

So the efficiency of the speaker is paramount and no matter what anyone tells you, to really hear what SETs do you need high efficiency: 97-98 at a minimum if your amp makes 15-20 watts. A 45-based amp needs a speaker that is more like 107 (if you really want to hear what it does anyway). This power limitation is one reason why I don't use SETs. The bigger you make them, the less bandwidth and detail.
Thank's Ralph. Does this apply to SETs specifically or to any low powered tube amp. The amp I'm considering is a 25W/ch 300b push-pull. That's Focal's lowest recommended rating for an amplifier to drive my speakers, but I've read advice (might have been yours) that those minimum w/ch recommendations always apply to solid state designs that increase their output as the impedance drops. That said, the amp that I have in mind is well made with pretty beefy transformers.
In analyzing your power needs it is not just a simple equation based on speaker sensitivity. You have to consider the size of your room, how loud you play it and type of music. What one person needs 100 watts for, another may only need 5 watts.
fwiw I push my 8 wpc Meishu (into 97 db AN speakers) pretty hard and always enjoy it, but I would not want less power...
You have to consider the size of your room, how loud you play it and type of music.
So true. My room is medium/large; speakers (TMM) are 87dB, min. 6.5 ohms, running full-range but are augmented by a pair of 12" self-powered subs. Power are a pair of Audio Mirror 45 Watt SET monos (Vlad says conservatively rated and able to handle peaks of 90 watts). But I do not listen at concert-level volume (average 80-85dB at seat). And the sound is glorious: clear, intimate, and great tone. I am thankful to find such a powerful, great sounding SET for my not so efficient speakers.
My speakers are 97 db and 16 ohms. I find that 30 wpc is not enough- its much easier to play the system if I have 60 watts. But the amps I use are designed to not generate any loudness cues to the human ear (unlike SETs, which rely on enhancing the 5th and 7th harmonics to get the 'dynamic' sound that SETs are known for), so I use the power without the system sounding loud. My room is 17'x 22' and is moderately lively with lots of diffusion. I do like to listen at higher levels, often reaching 100-105 db, but the system is relaxed at those levels and lacks any hint of being 'loud'.

I put 'dynamic' in quotes here and above because IME, many audiophiles when using that word are often referring to distortion of the 5th and 7th harmonics instead of actual dynamics. The way this works in an SET is the 5th and 7th harmonics don't show up until you really push the amp, which is usually on transients. So the loudness cues exist on the transients, but not in between. This is why SETs are well-known for being so 'dynamic' in a way that is out of proportion to their power. IOW its a psycho-acoustic effect.

This is why so many SET users play their systems at relatively low levels- the loudness cues created by distortion prevent them from wanting to turn it up. But if the system is designed to avoid these harmonics and has the ability to play louder, it will be very natural to do so.
Hi Mike, I don't think any of us can answer your question, we can only offer clues from our own experiences that may help you find YOUR answer. Here is a summary of my experiences.

I've been in this hobby over 40 years and have owned many different types of speaker. I finally settled on a design that pleased me for the past 19 years, until I changed those this past summer. My long-term speakers were a large, floor standing design that offered a full range response with very good soundstaging and tonal accuracy. They were rated at 90 dB and were touted to be "easy" to drive. But they were also rated at 4 ohms and their load dipped below 3 ohms at two point on the spectrum. Therefore, they were difficult to drive and I tried many different amps, SS and tube, medium and high power, before settling on 800 wpc mono blocs.

Within the last few years, three of my friends changed their systems to speakers of 97 dB or higher. As we frequently visit one another for listening sessions, I came to two realizations. First, high quality efficient speakers seem to offer more sense of "aliveness" than less efficient speakers, all else being equal (and here I would agree with those who suggest at least 97 dB to truly be considered efficient). And second, even with efficient speakers, amp matching is important to insure adequate power -- one of these friends progressed through a series of amps from about 4 wpc SET to about 16 wpc PPT and each power increase resulted in a more musical presentation.

Influenced by these listening experiences I sold my long term speakers and bought a pair of Cain & Cain BENs, rated at 97-98 dB. I'm still experimenting with amps but I've reinforced the idea that 15 to 20 wpc are needed to simulate live music experiences, even with such efficient speakers.

The other factor of course, and as others have mentioned, is the size and acoustics of your listening room, the type of music you listen to, and your preferred listening levels.

But my summary conclusion is that SS/tube/SET/PP/OTL etc. is not the critical factor. Finding speakers that suit you best, then searching out the best matching amp for THOSE speakers will be your key. Good luck and have fun along the way.
Thanks guys, a lot of great information here. I missed out on the speakers I was looking at, but I may try to grab a new pair of demos. I have been reading non stop, researching many different amps. I think I should change the speakers first before I get hung up on the amplification like many of you have recommended. I am in the process of changing my current amp for one that will work with both my current speakers and the ones I plan to upgrade too, then I can play with the super low watt SET's in the future.

Thanks again,
Breuninger, it was really cool to read your thoughts on this subject. I know you come from a place of experience and I've slowly been coming around to share your opinion.

Hearing you say that stuff makes me feel like less of a traitor for coming back to push-pull and solid-state amps on speakers that dip below 6 ohms and are less than 88db sensitive. Haha.
Atmasphere you said {This power limitation is one reason why I don't use SETs. The bigger you make them, the less bandwidth and detail} Please explain if you would for this doesnt seem to make sence, maybe its just wordered wrong. Maybe Im not getting your point. But power rating in SET doesnt have anything at all to do with bandwidth its the SETs design. Mostly the transformers used. I have owned SETs with limited bandwidth but if of proper build this isnt a universal SET problem. Now if you dont have power your loudspeaker requires thats a system matching error and not the fault of the SET amp but of owners system choice.
Johnk, the post was worded right. The upper power limits of SETs in a way are more of a function of the output transformer that it is the tube! The bigger you make the transformer, IOW to handle more power, the less bandwidth it will have. If you try to optimize it for bass, the highs will be rolled off and vice versa.

Since many high efficiency speakers (99db+) have limited bass response, SET builders usually sacrifice the bass performance in favor of the highs, since speakers that go below 40 Hz in the high efficiency world are few and far between.

IME experience the bigger SETs also have less detail. This is based on my personal listening experiences, but you will notice that one of the revered 'king' tubes in the SET world is the type 45, which usually makes less than one watt at full power. IOW, the smaller you make them, the better they sound, which is a common theme with amps in general (although OTLs seem to be one of the few exceptions), both SET and P-P.

I've also noticed that it is exceedingly rare to compare like technologies in the SET world. People often compare say a 300b SET against a P-P EL-34 amp (with the results in favor of the SET), but how often is a 300b or other SET compared to a P-P DHT class A amp of the same power rating? IOW to be scientific, this is where one would start if looking for real answers.
I went the other way - from a Cary CAD-805AE SET to the CAD-211AE push-pull amps. The reason for the switch was because the SET was underpowered for my new speakers. With the old speakers (ProAc D38's) the SET sounded magnificent with certain types of music - vocals, lieder, violin solos, string quartets. But the SET's could sound muddled when given something a bit more full range, like heavy orchestral. The symptoms were poor seperation of any instrument from the midbass down.

The CAD-211AE is an improvement in almost every aspect, mostly with dynamics, midrange weight, and almost unstoppable drive. But the top end is nowhere near as good as the SET. I was bi-amping for a while (see my sig) before I was forced to return the SET to pay the bills! If I could afford it, I would buy another pair of CAD-805's and bi-amp again.
My experience with SET was after several years of experimentation with SS and PP amps matched with a number of speakers. Most recently a few more systems have made their way through, and while some were quite good, I am always in a hurry to get my 300B SET/Altec 604 back on for the ease and sense of 'life' it conveys.

I have been very happy with my present main system for the last three years. The lower freq are augmented by two powered subs that have been set on a seperate volume and balance control to allow ease of integration with the mains. Further the two subs have varying crossover points to fill in any gaps. Not complicated in practice, but it took me a while to get it to this level.

Along with the well considered responses above. I'd like to add that the realism from this current system is quite stunning at times. Tho I'll be the first to admit the speakers could have better resolution, amongst other things... The whole effect as a whole is wonderful.

Give it a try and let us know how it goes...



HanaleiMike, take a visit over to the JE Labs website. you listen to acoustic instruments or a lot of electronic instruments? For the latter, some other kind of amp/speaker combo might be better.

My 300B amp measures flat well below 30hz. 30hz is the lowest range of piano. They also measure beyond the upper limits of my hearing capability. I need to measure my 45 amp (have much smaller, cheaper transformers) and haven't done so yet. I cannot listen to the 45 amp wide open but can listen at a decent level...too much distortion and I'm guessing it is what Atmasphere describes. In another forum JohnK told me minimum 300B for my speakers and he was right...for optimum performance. Thanks JohnK.

Speakers are 100db at one meter. I think I have roughly somewhere between two to four watts to play with before the distortion really starts to kick in and become relevant. Four watts is 106db. I would be inclined to agree with Atmasphere on how much power is required for these sorts of amps. This for live music type levels not quiet listening.

However, this should be more about enjoying the music/sound (overall frequency response throughout the music spectrum) based on how you listen and not getting caught up with the manufacturers' spec chasing of lower and upper bandwidth statistics.

Perhaps a bigger reason SETs are popular is price/performance ratio. Nothing comes close imho.
At the risk of appearing petty; I believe the lowest range of the piano is 27.5 Hz.
thanks Unsound...not petty at all

I knew it was 300 B SET measures flat below 27.5Hz at 4 or 5 watts (can't remember exactly)...amazing, eh?
The cutoff frequency of the amp does play a role. Generally speaking, you can hear artifact associated with the cutoff (-3db point) at frequencies up to about 10 times the cutoff frequency. So if the amp starts to roll off at 20Hz, you can hear artifacts up to 200Hz.

The same is true of the HF rolloff- except that now its 1/10th the cutoff frequency. So if the amp rolls off at 20KHz, you will hear artifacts down to 2000Hz.

This is why designers try so hard to get bandwidth!
hey Atmasphere...interesting. i have heard the argument for frequency extension on the upper end. what do you mean by "artifacts"? are these artifacts measured or only heard? please forgive me as I am not an engineer. i'm looking at a square waves and looks pretty good to me. thanks....