Enough SET Power for Rock and Roll


I'm still trying to figure out what SET amp would sound best for Rock and Roll (and other music but especially Rock) on Klipsch Cornwall II speakers (101dB efficiency) in a room about 18x13 (with kind of medium acoustics - not live, not totally dead.) On a Marantz 2230 (which sounds very good, surprisingly good for being ~35 years old and 30 watts of solid state) I found that when I crank up the Rock and Roll on the Cornwalls I'm listening from about 89dB to 97db, but frankly if I wasn't worried about clipping or blowing out the speakers or receiver I could probably enjoy an occassional 100 dB :) - but if I have to live at 97 dB and below I could. (Measurements made with a Radio Shack meter set on fast, C weighting - taken from 1 meter away from the speakers, and also at the main seating position which is about 10-11 feet from the speaker plane.)

From many posts here and over on AudioAsylum it sounds like a 45 SET amp would sound great but might not have enough oomph - although that isn't 100% certain. It seems that a 2A3 SET amp would have a better chance of handling the loud music and the "complexities?" of Rock (and orchestra music) vs. say simple instrumentals and vocals. Next up would be a 300B SET, more power but some people seem to think it gives away some of the "magic" of the 2A3 and especially the 45. It isn't so clear to me from reading the various posts how any of these tube types do on the low end; I think low end (reasonably deep and tight) is needed to do Rock and Roll well - but so is good midrange and highs, so it's a balance, of course.

What do you think, more power and listen loud with ease, ie go with a 300B, or can a 2A3 or possibly a 45 do it all? Or is it possible that SET just can't do Rock and Roll seriously with 101db speakers in a 18x13 rom? In which case, next up is what kind of tube amp? If SET makes sense, I'd like to give it a try but I don't want to push physics or the budget too hard with experiments that aren't likely to work.

Thanks!
hi_hifi

Showing 2 responses by larryi

It is really hard to say what volume level you are actually trying to achieve, and therefore, whether a particular amp or kind of amp is capable of delivering adequate power. Generally speaking, I would not expect power to be an issue with any 300b, 211/845 or tetrode/pentode used in single ended fashion (e.g., KT88, El34, etc. The 45 might be marginal and even the 2a3 might be marginal.

Aside from power, you need to first determine if single-ended sound is what will fit your sonic preference. Certain pushpull tetrode/pentode amps and many solid state amps deliver a harder edged attack to notes. This can be experienced as greater "slam" to the sound and might be preferred for rock music. Also, pushpull and solid state amps tend to have tighter sounding bass which adds "punch" to the sound. You need to hear a good SET amp (one with good output transformers is the key, and that generally means not a cheap amp), to decide if the sound is right for you.

As to the characteristic sound of particular tubes, there is considerable variation with brands and sound is also affected by the particular amps. Generally speaking, the 2a3 is the leanest sounding of the types you mentioned. It does not have as much upper bass/lower midrange as the other two and bas tends to be tight; the treble on a 2a3 is wide open and airy. The 300b is just the opposite-- it is warm in the upper bass and lower bass tends toward the loose side and there is less extension on top than a 2a3. The 45 is sort of in between. It has quite punchy, tight and deep bass and is warmer than a 2a3; it is also quite open on top like a 2a3 (for my taste, the only downside to a 45 is its lower power output). Properly implemented, ALL of these tubes can produce terrific sound, and it is a matter of taste and power requirement that will ultimately determine what kind of amp is right for you.

I personally think SET amps can do rock music extremely well. I don't listen at ear splitting levels, and at lower levels I really like what SET amps do with all types of music. At lower levels a good SET amp will sound more lively and vivid than a solid state amp or most pushpull tube amps.

One more thing, do not overlook output transformerless tube amps. This type of amp sounds VERY dynamic, lively and exciting. A 30 watt OTL would make a great "rock" amp coupled to high efficiency speakers.
I own a DHT pushpull amp that uses the 45 tube. It is a terrific amp--bass is tight and punchy, harmonic structure of instruments is fully saturated and realistic, and attack and decay of notes is very natural. These are all the qualities one would expect of DHT tubes. The biggest difference with SET amps is in soundstaging. SET amps tend to be better at presenting a big, enveloping soundstage in which the listener feels fully emersed rather than looking from outside in.

I mentioned high quality SET amp in my earlier post because there is a general impression that SET amps are lower in cost because of their simplicity. The problem with that assumption is that it is quite challenging to make decent output transformers for SET amps because of the high DC current saturating the core. The transformer is the key to a great SET amp, and good ones are not cheap.