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Just found this post comparing SS watts to tube watts.
Please let me post my personal onstage experience.
Shortest (incomplete) answer: they are the same; the speaker , which is a motor (voice coil + magnet) physically driving a mechanical load (cone+other moving parts+air) does not know or care what is feeding voltage into its terminals and supplying the current absorbed by its own internal impedance.
Then why do Musicians *perceive* the same specified RMS watts as louder when coming from a Tube amp than when coming from an SS one?
I have personally perceived that too, so if there is some "cheat", I for sure am also falling into it.
So there must be some Physics reason for it, backing the Musical difference, I don't believe in gremlins or magic.
I believe that if you hear something different, you must measure *something* different (or at least see something different on a scope screen).
I will open a can of worms here:
step by step, along 40 years, I have progressed little bit by little bit until I succeeded into developing and successfully marketing a 300W bass amp which holds its own side by side with a Classic Ampeg SVT (the yardstick by which Bass amps are measured).
This is not a Lab experiment, my B300 is the most sold high power amp in Argentina, used by the most important bands here, many of which *sold* an Ampeg SVT to buy one of mine.
Not only that, they come back later for more, or send friends, that must mean something.
They keep their 8x10" "fridges", though.
Or , say, a Peavey or Ampeg or Cerwin Vega 2x15" cabinet.
What's the difference with other, "regular" SS amps (as GK700, Hartke 3500, Peavey DataBass450, Fender 300W) all of which have been replaced with one (or two) of mine?
1) power device technology is not the cause: I went from 2N3773 (30 years ago) to MJ150xx (20 years ago) to IRFP250 (8 years ago) and the basic sound has not changed (well, MosFets are slightly more "brittle").
2) Power amp architecture isn't the cause either, I'm a minimalist and still use the most basic Linn structure.
No current mirrors, symmetrical differential inputs, constant current supplies, embedded OpAmps , etc.
What is important then?
3) No short circuit protection.
They cause all kinds of kinky very unmusical overtones even on proper speaker loads, simply because regular speakers are kinky crazy loads themselves.
All I use is a current sampler which latch triggers open a speaker relay when it does not like what's happening. It has 3 parts only (well, 4 if you count the relay anti-kick diode).
4) A *very* "loose" compressor.
Very different from most, which tightly control power amp input signal and never allow even 1% distortion, nor clipping, mine lets the power amp clip, normally up to 10 or 15%, quite visible on a scope.
5) It's very "fast" too, so much so that low frequencies "tremolo" modulate mids and highs.
So much so, that there is some of a "ring modulator" effect, bass notes take some of a "piano string" flavor, similar to Chris Squire's old "Yes" or Deep Purple "Machine head" sounds.
Beautiful with roundwounds on a Precision Bass.
The fact that it's quite non linear adds to this effect.
Did I mention I use a Fet *way* over it's recommended signal range?
Would you believe 1 to 9V RMS?
Yes, it becomes *quite* unsymmetrical, even with compensation. Lots of even harmonics.
6) What does it add up to?:
* Musicians sometimes drive a very powerful PA type power amp (think QSC900, AB1000 or 1500) straight from my preamp out; after some time they go back to the internal 300W I mentioned, because it "provides more stage presence and projection"
* They try to use it very loud "because it growls" or "it gets angry" ... similar to what Tube amps do.
* It never "farts", I not only don't boost bass, but even slightly cut it with a soft slope below 100Hz.
Anyway it has very low damping (value=1) so cabinets have a natural 6dB peak at resonance, at which frequency they are also *very* efficient.
I don't try to (equalize-boost) bass which the cabinet can't reproduce by definition (a recipe for disaster); on the other way this head auto-adjusts to whatever good response the cabinet has.
The relatively high internal impedance means that regular bass speakers sound somewhat sharper in the higher frequencies, while at the same time looser and underdamped around resonance.
I'll try to picture and post some waveforms, which clearly do not look like your regular SS amp ones.
I must have been doing something well, because my customer's database *is* the Who's Who of Argentine Rock.
These names are not known outside Argentina and perhaps surrounding Countries, but I have supplied these amplifiers to: Manal, Vox Dei, Raúl Porchetto, Pappo, La Torre (Patricia Sosa), Sandra Mihanovich, Les Luthiers, Sandro, Charly García, Nito Mestre, Crucis, Pastoral, Sergio Denis, Los Auténticos Decadentes, Hellion, Rata Blanca, Raúl Giecco, Dr Rock, Mercedes Sosa, Beba Pugliese, La Renga, Almafuerte, V8, and thousands of others.
What does all this boil down to?:
I have put my B300 side by side with an Ampeg SVT, each driving an 8x10", same signal going into both, volume up until sound starts to growl, and they stand shoulder to shoulder as equal brothers, although each one has its own characteristic "signature".
Other similar SS amps as the ones I mentioned before either lack presence and punch, don't "cut through" (the ones with tight compressors) *or* go all the way, either fart or sound like buzzsaws ... or both. (the uncompressed ones).
These *can* be heard, or cut through ... but you'd prefer them dissappearing.
EDIT: before somebody points out that "(electrical) watts can't be heard", I hope I made it clear that I am comparing *electrical* watts driving the same enclosures, which thus have the same conversion efficiency by definition.
Please let me post my personal onstage experience.
Shortest (incomplete) answer: they are the same; the speaker , which is a motor (voice coil + magnet) physically driving a mechanical load (cone+other moving parts+air) does not know or care what is feeding voltage into its terminals and supplying the current absorbed by its own internal impedance.
Then why do Musicians *perceive* the same specified RMS watts as louder when coming from a Tube amp than when coming from an SS one?
I have personally perceived that too, so if there is some "cheat", I for sure am also falling into it.
So there must be some Physics reason for it, backing the Musical difference, I don't believe in gremlins or magic.
I believe that if you hear something different, you must measure *something* different (or at least see something different on a scope screen).
I will open a can of worms here:
step by step, along 40 years, I have progressed little bit by little bit until I succeeded into developing and successfully marketing a 300W bass amp which holds its own side by side with a Classic Ampeg SVT (the yardstick by which Bass amps are measured).
This is not a Lab experiment, my B300 is the most sold high power amp in Argentina, used by the most important bands here, many of which *sold* an Ampeg SVT to buy one of mine.
Not only that, they come back later for more, or send friends, that must mean something.
They keep their 8x10" "fridges", though.
Or , say, a Peavey or Ampeg or Cerwin Vega 2x15" cabinet.
What's the difference with other, "regular" SS amps (as GK700, Hartke 3500, Peavey DataBass450, Fender 300W) all of which have been replaced with one (or two) of mine?
1) power device technology is not the cause: I went from 2N3773 (30 years ago) to MJ150xx (20 years ago) to IRFP250 (8 years ago) and the basic sound has not changed (well, MosFets are slightly more "brittle").
2) Power amp architecture isn't the cause either, I'm a minimalist and still use the most basic Linn structure.
No current mirrors, symmetrical differential inputs, constant current supplies, embedded OpAmps , etc.
What is important then?
3) No short circuit protection.
They cause all kinds of kinky very unmusical overtones even on proper speaker loads, simply because regular speakers are kinky crazy loads themselves.
All I use is a current sampler which latch triggers open a speaker relay when it does not like what's happening. It has 3 parts only (well, 4 if you count the relay anti-kick diode).
4) A *very* "loose" compressor.
Very different from most, which tightly control power amp input signal and never allow even 1% distortion, nor clipping, mine lets the power amp clip, normally up to 10 or 15%, quite visible on a scope.
5) It's very "fast" too, so much so that low frequencies "tremolo" modulate mids and highs.
So much so, that there is some of a "ring modulator" effect, bass notes take some of a "piano string" flavor, similar to Chris Squire's old "Yes" or Deep Purple "Machine head" sounds.
Beautiful with roundwounds on a Precision Bass.
The fact that it's quite non linear adds to this effect.
Did I mention I use a Fet *way* over it's recommended signal range?
Would you believe 1 to 9V RMS?
Yes, it becomes *quite* unsymmetrical, even with compensation. Lots of even harmonics.
6) What does it add up to?:
* Musicians sometimes drive a very powerful PA type power amp (think QSC900, AB1000 or 1500) straight from my preamp out; after some time they go back to the internal 300W I mentioned, because it "provides more stage presence and projection"
* They try to use it very loud "because it growls" or "it gets angry" ... similar to what Tube amps do.
* It never "farts", I not only don't boost bass, but even slightly cut it with a soft slope below 100Hz.
Anyway it has very low damping (value=1) so cabinets have a natural 6dB peak at resonance, at which frequency they are also *very* efficient.
I don't try to (equalize-boost) bass which the cabinet can't reproduce by definition (a recipe for disaster); on the other way this head auto-adjusts to whatever good response the cabinet has.
The relatively high internal impedance means that regular bass speakers sound somewhat sharper in the higher frequencies, while at the same time looser and underdamped around resonance.
I'll try to picture and post some waveforms, which clearly do not look like your regular SS amp ones.
I must have been doing something well, because my customer's database *is* the Who's Who of Argentine Rock.
These names are not known outside Argentina and perhaps surrounding Countries, but I have supplied these amplifiers to: Manal, Vox Dei, Raúl Porchetto, Pappo, La Torre (Patricia Sosa), Sandra Mihanovich, Les Luthiers, Sandro, Charly García, Nito Mestre, Crucis, Pastoral, Sergio Denis, Los Auténticos Decadentes, Hellion, Rata Blanca, Raúl Giecco, Dr Rock, Mercedes Sosa, Beba Pugliese, La Renga, Almafuerte, V8, and thousands of others.
What does all this boil down to?:
I have put my B300 side by side with an Ampeg SVT, each driving an 8x10", same signal going into both, volume up until sound starts to growl, and they stand shoulder to shoulder as equal brothers, although each one has its own characteristic "signature".
Other similar SS amps as the ones I mentioned before either lack presence and punch, don't "cut through" (the ones with tight compressors) *or* go all the way, either fart or sound like buzzsaws ... or both. (the uncompressed ones).
These *can* be heard, or cut through ... but you'd prefer them dissappearing.
EDIT: before somebody points out that "(electrical) watts can't be heard", I hope I made it clear that I am comparing *electrical* watts driving the same enclosures, which thus have the same conversion efficiency by definition.
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