SET with inefficient speakers

I don't know what the impedance "graph" of your Dali's is but if doesn't flucuate wildly and/or dip much below 4 ohms, you should be fine. I have run my Maggies with an 845 and 300b SET for kicks. Turned out pretty good within its limits.

Doesn't look like a good match, Dali recommends 50-350 wpc for the MS4. Seems to me that they designed the speaker specifically for amps of higher power.

But, for the sake of discussion, how much are you looking to spend?

The most important thing with SET amps and speaker matching is the speaker's impedance curve, much more than sensitivity. For example, an 88dB speaker with a ruler-flat impedance curve is a much easier load to drive for a SET amp than an 92dB one that dips to 1 ohm at times.

Unfortunately, Dali does not supply impedance curves for the Euphonia MS4 on their website, so it makes it hard to even guess how they would perform with SETs.

And you haven't specified if you are interested in Flea-powered(<2 wpc), low-powered(< 8wpc), or high-powered ones (20-50 wpc). There are even a few ultra-exotic amps that reach the 80-150 wpc range(NAT Se3 & Wavac HE-833Ver1.3, respectively).

One thing that might make it possible is that your MS4's are bi-wireable, so that you could drive the woofers(usually most power demanding) with a solid state or high powered amp and the tweeters/ribbons with a SET amp.

Although, there is one argument against this - the MS4's crossover to the tweeter/ribbons ~3Khz, which is little to high to get all the midrange benefits of SE triode glory.

It will work fine. 88db isn't so bad. Just don't ever expect real bass and you'll be happy.

In theory, if the speakers will give you 88db for one watt and you listen around 80 db, it will work. In theory. Try before you buy.

I drive 89db Acoustic Zen Adagios with a 22 watt 845 SET no problems, but as darkmoebius say's, it is the impedence that is the vital point. The Adagios are pretty flat and do'nt drop much below 6.5ohms. In fact, my SET had better grip on the speakers than a good 180watt SS amp I was using.

As always, I think you have to try a possible candidate in your room, with the speakers

Art Audio Jota - hi-power, hi-current version(different tubes, larger transformers). These amps can drive loads that very few SETs can even dream of. But, it will cost ya'... $13k new, ~$6.5k used

My mains are not ver efficient at 87dB 8ohms (TMM, M's are 6") with not ruler flat impedance curve, and mfr. recommends min. 85wpc, but I have them high-passed at 85Hz, augmented with two subs. On paper not ideal, but they sound wonderful with pair of 45 watt SET monos. And loud enough for me (ave. 80-85dBs at seat). Glad I tried them out instead of being scared away by the speaker specs. Best to try if you can. It is part of the fun.

On their website Dali claims to have a very flat impedance curve. If so, you'll be able to drive your Dali well with a 10wpc SE amp w/o much problems.

BTW, I drove 88db efficient speakers with a homerolled 2.5 wpc amp and the bass was astonishing. Much better than a 50wpc Nad I normally use to run in speakers or to hold the door open.

Check out Dehavilland's SET amps. They are higher powered than most SETs, and designed with the goal of being compatible with many speakers that otherwise wouldn't work well w/SETs. Their website and all your basic research will give you plenty of info.
I am using their 30w Aries 845Gs to drive Alon V speakers that normally recommend much higher power. Most listeners can't believe that I'm driving them with SET amps. Cheers,
Spencer

After owning all types of gear (some very expensive and powerfull) I have downgraded to the diminutive Shanling MC-30 receiver (absolutely fantastic value). Tube preamp, SET 3-watt amp (yes, that's SET!), cd player and tuner all into a single stunning chassis. All for not much money. Actually, the cd player alone sounds like twice the price of the whole unit. I had purchased this to use it only as a cd player to be paired with some powerfull monoblocks. When I tried this gizmo on its own, with no power amps, I just could not beleive the proverbial jaw-dropping sound with just 3 watts....sort of makes a lot of other gear look overpriced to me right now.

Paired with my 89db Opera Quintas, I get great, full sound at low-moderate volume.

My personal opinion on the subject:

If it sounds good, it is easier to accept power limitations.

If it sounds bad, power won't make up for a better experience unless one likes noise.

Good luck.

its not impedance alone that will get you, but rather a combination of low impedance AND hi phase angle. Meaning a highly reactive load.
More info on the speaker, including some real measurements would be helpful.

I prefer low impedance, a 180 degree angle, preferably on a sofa, phase-reversed continuous ohm calibration along with a non-reactive by-passed load of no more than 100 cryogenic microfads wrapped up in double-wound 100% oxygen-free copper, originating from planet Krypton.

Another route, a bit simpler maybe, would be to just sit-back and relax with a glass of wine, forget hi-fi and enyoy music...and life!

No offence intended, with a grain of salt !

Tim,

It is hard to predict whether or not a low-powered SET will work for you -- it depends on your taste and priorities, how loud you need your system to play, the particular characteristics of the amp you audition/buy, etc.

I will hazard a guess that a SET amp is within the realm of possibility, but, whether that would be an optimal choice is harder to guess at. When one looks at numbers, most low powered SETs seem completely unsuitable for all but the most efficient commercial speakers. But, I think most people will be surprised at how low a wattage is needed for satisfying volume.

Sonicbeauty raises a very good point about SET amps, or for that matter, any truly worthwhile "improvement" to a system. As one improves quality, the volume level that one tends to listen at should go down as the listener will not be trying to compensate for lack of resolution or poor dynamics with higher volume.

While SET amps using higher power transmitter tubes (845 and 211) will make power much less of an issue, they tend to give up something in the way of performance to the much lower powered tube types, such as the 2a3 or 45. They tend to be more expensive, too, because of the need for a beefier power supply and high voltage wiring. If you can listen to both low and high power types to assess the tradeoffs.

Another consideration is that a SET amps that truly represent what this genre is capable of delivering tend to be quite expensive. While the circuitry may be simple, really good parts are required. In particular, SETs require transformers designed specifically for this use and really good single-ended transformers are very expensive to produce. When priced on a $ per watt basis, SETs seem even more pricey. But, with compatible equipment, the sound is quite special.

Anytime speakers are being driven by less than the ideal amount of power, "success" will be pretty subjective. I know people who use SETs (not flea power) to drive speakers that spec like yours, and state that they hear no benefit with additional power. I seldom share their assessment. Even when I like the sound a lot, I can still hear gains with an increase in power. There is no right or wrong here. It's just one of those times when there is no substitution for listening yourself.

Anything worth doing, is worth doing right.

In the SET world, that usually means starting with efficient or SET-friendly speakers and building your system from there.

Any other approach, outside of luck, leads to a lot of trial & error, with most of it being on the error side.

Agree with Darkmoebius. Many of course not all of the SET posts that are - are coming from folks who expect SET to run most any loudspeaker. Sure some guy will post that his SET drives maggies or 80db 4 ohm BBC monitors. Sure they do music will come out but why not try for synergy. If loudspeaker needs power use amp with the right design power ohm rating for loudspeakers used. We know that load effects responce and levels of distortion of running SET into the wrong loudspeaker will be much greater than running loudspeakers designed for SET use. Plus frequincy responce will not be ideal.

Having recently purchased some NAT SE2SE amps which produce about 70 watts each to drive my Soundlab speakers has shown me that you MUST listen in your own system to achieve what you are trying to accomplish. The NAT SE2SE drive my Soundlabs with ease and authority and if I followed some "informed" opinions my new discovery wouldn't have been realized. I say any person that has doubts about "high powered" SET amps particularly NAT SE2SE driving their inefficient speakers should seek out these amps they are a revelation and are self-biasing.I have had my speakers for nine years and have never heard them produce music so glorious and awesomely real.I have no relationship with any dealers or manufacturers just a music lover. Try them out you will be amazed how your system will sound!!!!!

Nice thing about audiogon, you can roll amps as easily as you can roll tubes...

I'm having success with a tubed amp on my speakers, despite manu claims that they 'sound best' with SS amps. I have a Cary Rocket, definitely not SET, but the power output in UL mode is "only" 60w (which sounds better the triode @ 30w -- i think the speakers really like the increased power). This amp bested all the SS I had before, including some 200W Nuforce class D's. Speakers are rated @ 150W, and I'm glad I took the gamble.

My point is, don't always believe the specs, or even the manufacturer! But it's still important to keep numbers in mind if you want any hope of synergy.

Tholt
Yeah, Audiogon has given me the chance to "find" nirvana in this maddness.I don't roll amps often. I was once on the high power kick but found that's not always the solution in trying to get that "match made in heaven" sound.Well,with the addition of the NAT SE2SE amps I think and hope this is the end of this journey searching for amps to power Soundlabs.

Sonic,
One of the biggest myths in audio is the impedance myth. Tube guys will talk about various tube till dawn, spouting opinions about what does or doesn't sound better, but audiophiles of all stripe typically ignore some of the measurables which are known to effect quality and equipment compatibility.

Yep, by all means enjoy, but don't frustrate yourself by trying to get a SET shoe to fit a B&W foot. You may get your foot in there, but will be in pain after walking 5 minutes.

If my references were a little opaque for you, try reading up on some of that kind of theory. Instead of turning compatibility into a guessing game, a little info going in will enable you to avoid some blind alleys, perhaps.

Sorry for getting wound up. I think speaker designer/builders need to sit down for a long chat with amplifier guys.

Magfan, you got that right... I usually show the speaker guys this
http://www.atma-sphere.com/papers/paradigm_paper2.html

-and then see if they have any questions. If the question about which paradigm group the speaker or amp fell into was marked on the specs, and if everyone knew what that meant, speaker/amp selection would be a lot easier!