A watt is a watt is a watt?

[dmannnnn]

Is it?  I'm sure this has been beaten to death around the forums, but I am still puzzled over the SS watts vs. tube watts debate.  There can't be a difference, can there?  Is this a matter of current output?  Do tubes just sound more powerful/louder because of the full, rich sound they make?

Regarding current.  What is the range of current outputs in home audio amplifiers?  At what point can an amp be considered 'high current' and where do SE triode amps fall in this range?

My new(used) pair of Magnepan MG12's has gotten me thinking about this.  I am thoroughly enjoying them with the paramount 300b's.  They run out of steam pretty quick, but for everything but rock and roll and big symphonic music they work just great in my smallish room.  There can be some sybillance or maybe distortion at the very top.  This might be due to the big impedance drop at the very high frequencies.  But it is very minor.

I am quite convinced that 60 watts will be plenty for the maggies to do it all.  The formula says this will give me a 9db increase in SPL's.  I think 6db would be more than enough.  Unless there are other factors I do not know.

PS santa was a beast this year.  He brought me a pair of Cinemag 3440A's, a copy of The Speaker Design Cookbook, and a cordless drill to do the damage!  The maggies were my reward to myself for making through 2009 in one piece.

 

[Grainger49]

See if you can find a local guy with a Stereo 70 who will bring it to your house.  That is a good 30 + WPC.  That will give you some insight.

BTW, I do believe most tube amps sound dynamic than transistor amps.  That is a generalization, of course.

 

[ssssly]

Your MG-12s are 86db. Your Paramounts are ~9 Watts. That is really on the edge. My MMGs are hooked up to my home theater amp pushing ~300 watts. And even with that much power going to them, the amp runs out of steam before the speakers. Magnepans are nice sounding speakers but they are very inefficient. They just want to be hooked up to huge amps. The kind you need a dolly to wheel into the room.

I have listened to the MMGs with my ST-70 and it wasn't bad at all. Could pull it off in a small room for near field listening. But even in my modest living room, the MMGs required more wattage than the ST-70 could provide to really sing.

One thing you could try is integrating a mid/sub. MGs are significantly more efficient if you cross them over above 500hz. Can also play with your output cap size to try to tame that high end warble down.

 

[Paul Joppa]

You bring up several interesting issues.

I'd like to address the current issue first. Almost everything you read is about solid-state amps with no output transformer. They generally put out a fixed maximum voltage (the power supply voltage), so the lower the speaker impedance the more current they demand. The Maggies are 4 ohms so at the full power supply voltage they would demand twice the current of an 8 ohm speaker. Many inexpensive amps can't deliver that much current, at least not for very long.

Tube amps on the other hand have transformers with taps, so they can trade off current for voltage. On the 4 ohm tap they will deliver the same power as on 8 ohms, by changing the turns ratio so you get 70% of the voltage at 140% of the current. The concept of a "high-current" tube amp is not so meaningful, since the current/voltage relationship can be altered to match the speaker. A good analogy is that a high-torque motor is necessary in a car with no transmission, but as long as you can downshift (i.e. change the transformer tap) you don't have to care about the engine's torque as such.

There are a few other reasons tube power does not work quite like solid state power. The main one is that tube amps will usually overload gracefully, especially those with little or no negative feedback like SETs. You can drive them surprisingly far into compression and increasing distortion before they sound really nasty. Solid state amps usually exhibit hard clipping, and sound pretty uncomfortable with only a small excursion into overload. There are a couple, more subtle reasons having to do with the different distortion harmonic structure of feedback circuits. But the bottom line is that many experienced listeners want on average a 6dB greater power capability when using good quality solid state amps.

Incidentally, the MG12 is a 4-ohms speaker rated 86dB at 2.83v which is 2 watts. The efficiency is therefor 83dB/w/m. This rating method makes sense for solid state amps, but is a little deceptive for tube amp users.

 

[JC]

I think Paul Joppa's penultimate paragraph talks about the bulk of the difference.  A Watt is indeed a Watt, it is a definable quantity of power.  And, if that were the only consideration, then all amps of a given Wattage would re-produce audio identically.

Tube amps simply have the bulk of their harmonic distortion components in a more pleasing harmonic, and they tend to ease into distortion in a considerably more gradual way, as a rule.  There are a virtually unlimited number of other factors, of course, but I think these two comprise the bulk of why one may get the impression that "tube Watts" are somehow more robust than "SS Watts".

 

[dmannnnn]

Thanks for all the great information.  I get a little smarter every time I come here.  It seems that a quality SS amplifier with the speed and detail worthy of the Magnepans will cost somewhere in the $700-$1200 range used.  The tube amps I am contemplating are in the same range:

New: Bob Latino's ST120 and the DIYHIFI Ergo Ella 

Used: AR-D75 or a pair of Golden Tube Audio SE40's (80 WPC).  Maybe Qucksilver 60wpc monos

SS amps I am considering include: Monarchy SM70 Pro monos, McCormack, McIntosh 2100-2150-2250, Classe CA100, and Odyssey Stratos.  The new ICE amps get alot of press but I don't know much about them.  Any feedback on all the amps listed would be great.

Whichever I end up with will be fed by the Foreplay.

 

[Len]

SS amps I am considering include: ... McCormack, ...  Any feedback on all the amps listed would be great.

I had a McCormack DNA-1 Deluxe feeding a pair of Definitive Technology BP2000's with built in subs.

I built a pair of original paramours and hooked them to a pair of KLH Model Seventeens. I sold the SS setup to build more tube stuff.

The SS setup was kinda amazing. In classical symphonies, you could hear and place (even though the speakers were bipolar) every instrument, with loads of separation. Tons of power, quick bass too. But for some reason, it did not make me want to dance to rock, and I did not find myself closing my eyes and falling into any kind of music. It was great for home theater, friends were impressed.

I've had a bunch of high end SS stuff and it has its strong points. For me, its strong point is not making music.

I think if you can keep a high power tube amp going (some are high maintenance), you get a lot more out of it for music reproduction than from SS. For voice and HT I'd say solid state.

But that's just my taste and my opinion.

 

[Paul Joppa]

Every so often, Maggies come up and I recall a VALVE meeting, now more than 10 years ago, where we listened to Doc B's Maggies (now long gone, I don't remember the model). I'd heard them a few times before, but the only time they really got up and sang to us was when he hooked up the MaciIntosh MI-200s. Two hundred watts of P-P transmitter tube power, baby! On quite passages you had to work to ignore the cooling fans on these industrial monsters...

 

[dmannnnn]

Yea, I guess to really get them to open up will require some big watts.  More than I can afford in tubes.  I'm still curious to hear them with 60 tube watts each before I make a decision.  My new living situation will preclude many loud sessions.

 

[Grainger49]

PJ is right a watt is a unit of energy (the rate energy is being dissipated) that can be had in a number of ways.  In our stereos we have three variables, voltage, current and impedance.  The speakers have different impedances at different frequencies.  The amplifier puts out a voltage and the speaker "draws" a current that is the resultant of the voltage put out and the impedance presented at the frequency being produced.

It is enough to make your head swim.  Even simple speakers like the Maggies have some crossover in them that screws with the impedance seen by the amp.  Crapola!  Nothing is easy.

But the wonderful thing about our hobby is the guys in it.  See if there is someone who wants to schlep his amp over to listen.  Entice him with beer and music.  Try a number of amplifiers.   You have nothing to lose and only a friend, and possibly more knowledge about amps, to gain.

Frequent posters knew I was going to suggest this.  It only matters how the amp sounds in your system in your room.  Not what all of us out here think.