Horns + tube amps: can they handle LOUD like SS?

You might be interested to know that the amps used by those guitar rockers were more than likely tube amps like Fenders and Marshalls. Their power rating was probably not as high as you think. Most guitar players know that a 25 watt tube head will play louder and better than a 100 watt SS rig. Some people wonder how that can be. It just is. It is a similar case with home audio. It would not surprise me if a 50 to 75 watt tube amp would play louder than your 200 watt SS amp. Also, if and when distortion is reached, the tube amp produces even order distortion which is easier on the ear than the irritating odd order disortion off SS. So the clip is softened with tubes. However, you can't expect a 3 watt 2A3 amp to produce stadium level sound. If you want loud and clear, I would suggest a Berning ZH270 ZOTL tube amp. This design has 70 powerful watts of very clean, fast, and pure sound that will drive your Klipsch speakers to very loud levels and sound very clean while doing it. It is a push/pull amp, but a very good one with the speed, weight, and authority in the bass that one expects from big SS rigs, but the clarity and sweetness of OTL tube amps. Of course, if you can afford more money the Tenor 75 watt OTL's will also do a great job on the Klipsch. They will also play plenty loud and clean. The big AtmaSphere amps will do a great job as well. These are some of the finest amps made today. The little amps under 8 watts are made for a different purpose, which is to provide the ultimate purity of sound at a more reasonable SPL. Every thing has its trade offs. Nothing is perfect. You just have to do system matching with the gear that suits your listening tastes and budget.

Simple and clear:
Transistors have a very small region of linear operation in their output characteristics(Volt-Ampere characteristics)and have to operate at less-than-half of their rated output power.
Tubes have 90% of linear region and can be basically driven to almost clipping. Thus, the tube amp 50W/ch can easily overscream SS with 100W/ch since SS will "choke" much earlier.

I would HIGHLY recommend reading the "white papers" on the Sunfire amps to see how most SS designs operate. This will give you a better understanding of why they sound "grainy & gritty" when being pushed. Bob Carver puts it into words that are quite easy to understand. He also looks at things from a slightly different angle than most others, so it is both refreshing and eye opening ( in my opinion ).

As to the SS vs Tube power ratio, i would say that a good tube design of 30 - 50 wpc would be equivalent to a "typical" SS design of 100 wpc in terms of "clean music power". This has to do with the differences in transfer function between tubes and transistors and the ways that they "saturate" or "clip". SS clipping is much harsher sounding ( in most cases ) and is typically pretty easy to detect. Tubes can be driven into occasional clipping and you may never notice.

As to TWL's comments about guitar amps, the main reason that guitar players prefer tubes are for the very reasons that i just mentioned: clipping and saturation characteristics. I don't think that it has much to do with volume capacity at all. Tubes simply produce FAR more "pleasant" overdrive, harmonics and sustain characteristics than SS amps are capable of. Besides that, they just sound "richer" with added emphasis to the "warmth" region and don't sound as "screechy" on the top end. As such, many rock / metal guitar players actually prefer a smaller ( 50 watt ) head to a larger ( 100 watt ) tube head because it is easier to push into clipping and keep there. The fact that this chews the hell out of the tubes is of little concern to them so long as they can get that "chunky" sound that they are after.

For the record, i've got a set of La Scala's and Heresy's and have used them with several different BIG power amps many times over. I am currently running them with a "vintage" 30 wpc tube amp and it sounds very nice. While it will not "deafen" you with slam and impact by any means, they do mate quite nicely together.

If you've read some of my posts pertaining to spl and power levels, you will know that I am of the opinion that increased headroom in a system ( both speakers and amp ) are a big benefit. So, if you want to rock and use tubes, look for something that is a little stouter than what i have. This will give you the reserve capacity that i mention without having to push the amp or tubes to get the volume levels that you want.

I would look for a 70-100 wpc tube amp. That should give you everything that you are looking for i.e. volume and reliability. A smaller amp is just not suitable for "headbanging levels" in my experience. Others may disagree, but that's what i've found to work.

By the way, Patricia Barber and Diana Krall sound quite good on this type of system. You may find that the better your system is, the more versatile it becomes and your tastes may begin to broaden slightly. In case you're wondering, i'm speaking from experience : ) Sean
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The music you like and your preferred playback volume levels mitigate against going low-power SET. Ultimate purity of harmonic structure is not as important a factor for replay of hard rock music as are high-volume capability, full frequency range, and dynamic slam and control. Having said that, I'm betting that the "100w" SS amp you heard distort into the Klipschs before wasn't a high-end piece with a sturdy power supply. On those speakers, a quality 100w piece, be it tube or SS, should certainly not give up before you do (or the speaker does). Since you say you are "happy as can be" with the SS C-J amp that's in your system already, hold on to it. If you experiment for curiousity's sake, you probably will hear a difference with a tube amp, but not because of the way it clips (if you select it correctly). Rather, the overall presentation may take on a somewhat different character than what you're used to, maybe spatially as well as tonally, but it'll be up to you to choose which is preferrable. Even efficient speakers with large woofers need some amp power to get a handle on the bass, so if you audition something tube-wise, I would suggest a push-pull tetrode or pentode design of around 80w minimum or up (VTL makes some nice sounding stuff with high power for the $).

About the guitar amp points raised above, I just thought, as a guitar player, that I might comment. It's true that most stuff in the HM/hard rock genres made since the late-60's has been played through tube amps (particularly Marshalls and their derivatives, themselves derived from the older original Fender Bassman design of the 50's) with anywhere from 50 to 200 rated watts per amp head - with multiple "stacks" prevelant, meaning many heads working simultaneously to achieve a very high-volume "wall of sound". But it's also important to realize that this choice has mostly to do with the sound of an amp's distortion - not how loudly it can play and stay clean. Since the harmonic structure of a tube amp run in clipping produces distortion that is musically consonant, whereas a SS amp's is not, tube guitar amps have remained the popular choice for their characteristic distortion sound, not their volume capability per se. (This explains why, in a recording studio situation where high absolute volume is not necessary to get a sound into the mic and on tape, small tube amps that distort easily at lower volumes have long been popular. Although Led Zeppelin was known for Jimmy Page's Marshall stacks onstage, he often recorded in the studio with tiny vintage Fender and Supro amps, good for only a few watts.) Since in hi-fi reproduction we don't want any clipping to occur (or even come close to it, ideally), the character of an amp's overdriven sound should not be the issue.

P.S. Rats - NOW I see that Sean has beaten me to the "Submit" button...

Thanks for all the insightful follow-ups and recommendations. I am indeed interested in trying a tube amp out of pure curiosity, just wanted a rough idea where to start. As for the Carver white paper, I bet it'll be easier to understand than the 70's Radio Shack/Texas Instruments "beginners" guide to transistors I've been chewing on.

Thanks all for your help!
mwilson

ps: the 100w amp that couldn't was a B&K ST140, I have no problems with it paired with some Wharfedale towers in the basement
ps2: Sean - you know what recording actually sounded best on this system? Elton John on vinyl! Sadly, much heavy rock suffers from poor recording, as you seem to know.