Do you mean the Widor symphony #6, allegro recording by Kraybill on Reference Recordings? If so, I agree that she does a fine job on this and the other tracks, although I'm using ML hybrid electrostats and sub woofers/DSP with 160W/channel tube amps for the panels and built in class-D amps for the bass units.
Class A versus A/B
- Thread starter opusarlo
- Start date
I drive a pair of ML electrostatics that have input impedances from >1k resistive at 300Hz to 0.9ohms resistive at a bit more than 20kHz using a pair of Rogue M180s with no problems (other than a very musical roll off by a few dBs at 20kHz. Many well designed amps can handle very large excursions in load impedance these days.
Speakers don't present resistive loads.
sure, let's see it doing it at over 1KW/chanel stable on 1R
I thought you did not care much about specs??
edit:
you do make a good point, though, for a small kit amp, the F5 specs are impressive.
since you are saying it sounds so good, I might make it a project at some point.
Electrostatics with an active woofer with a fairly small load R and a relatively small cap do- more or less- at least at the extrema that I described.
At resonance (the greater than 20kHz frequency) the load is entirely resistive, and at the cross over the reactive (capacitive) impedance is significantly higher than the real part so all frequencies less than that look resistive.
In between the impedance goes from mostly real to mostly capacitive, and then, as I said, entirely real at resonance, and inductive from then on up.
sure, let's see it doing it at over 1KW/chanel stable on 1R
I thought you did not care much about specs??
edit:
you do make a good point, though, for a small kit amp, the F5 specs are impressive.
since you are saying it sounds so good, I might make it a project at some point.
I've never understood why anybody would need that kind of power. Or even 500 watts. I have an average size living room and I don't use all the power I've got with 90dB sensitive speakers.
The F5 is a nice amp, but I personally believe a custom built amp will sound better than a mass produced amp every time. The F5 had the right characteristics for the speakers I have and the sound qualities I wanted. If I had Klipsch LaScala I wouldn't have built an F5. I'd have built an Aleph J.
Power JFETs are a thing again and I wish I could play with some of those.
...and you are entitled to you own absolute statement / opinion which is same as saying that if I built a hot rod in my garage, then I would claim it is better than the top of the line Ferrari. How absurd do you think I would sound, if I'd be serious enough to claim such thing?
I am not sure that you had the opportunity to listen to an MX-10000, BX-1 or even a B-1?
If you are talking about custom, can any kit amp get any more custom than a B-1 as an example? A circuit design like no other, lab test equipment-built quality, even custom made SIT devices used in no other model amplifier. Can a kit amp get more custom than that?
Mr Pass made his own SIT and the First Watt SIT-3 amp sales for $4k, but c'mon, it would be like comparing the sizes of a mouse and an elephant in term of the necessary investment and R&D necessary just to produce a Pass SIT or a Yamaha K77.
...and what should the 200w B-1 behemoth sale for, if it were just built today? and what about making something in you shop that is more custom than a B-1...I mean not copy it, but do the R&D to design the circuit, do the R&D to produce the first SIT batches, produce all the parts without any economies of scale...etc.
why not go for the real thing?
If you have the opportunity, find a sony of yamaha V-fet amp, tweak some of the shortcomings of a 40+ years old amp and you will have a custom amplifier when you are done, and a bargain considering its fidelity.
I am not sure who needs that much power either. The MX-10K is rated at 250W into 8R but if you have hungry speakers it is stable at 1KW @1R. Some ppl have hungry speakers and want the headroom. That is the only explanation I can think of.
Plenty of small garage operations bang out cars that would destroy a Ferrari on the track. For instance, the Ariel Atom V8.
As for the Yamaha and Sony JFET amps, which is what a VFET really is, they're stupidly complicated amps. If I ever ended up with one I'd just rip the FETs out and toss the rest. I think more interesting things can be done with them.
I've heard lots of nice, and complicated, amps. They do lots of things well, but they aren't doing what this amp does with these speakers. It's the difference between buying a suit off the rack and having one tailored. No matter how nice the rack suit is, it's not tailored. It's not a question of shortcomings. It's a question of taste.
Getting back to the debate, that NEED to overcome certain shortcomings with class AB gets in the way of more finely tailoring the sound. That's why I'm not terribly interested in it. Class A is simply closer to the ideal in a very simple architecture and leaves more room for play, to get away from the technical and add some art to the experience. The only thing I've ever actually measured on my amp is the bias. For the distortion I just centered the P3 pots and started turning them little by little until I heard what sounded right. A little bit of carefully considered distortion can make an amp better than perfect.
Yeah, for 5 minutes maybe. Top manufacturers such Porsche, Ferrari and others spend millions in R&D to so that their GT cars run races for 24 hours at crazy speed and you think that a garage
bang-out could do the same or better...... You lost me there.
Yes, true to some extent they are. Question for you: Why aren’t the new power Jfets called V-fets?
have you tried other well executed A, AB amps with the same speakers? what about a V-fet amp? maybe a Krell Class A? what else have you expereinced with in order to make these absolute statements?
I am not disagreeing that your speakers sound very good with your amp, because I have not heard them...But absolute best?? I would personally refrain for makins such statements. Someone new to this forum would think that if they bought the same set of speakers and an F5, they would have the best audio system in the world....
You did make me curious and I am thinking on building the F5. Are there more flavors of it? I see mention of F5 Turbo?? I guess I need to spend some time on DIY audio.
Yes, a good argument, but then I 'd say you need to go to an active speaker solution.
most of the ancillary circuitry in the V-fet amps is to protect the v-fets. and specific to B-1, there is also a balancing bias mechanism to make up for the slight differences of pI hysical characteristics of the two output devices.
Take away the state of the art protection circuit in a B-1 and your chances to kill a unicorn are exponentially higher. The protection circuit adds nothing to the sound. If you noted I mentioned that you could customize the existing V-fet amp. Minor improvements would yield perfection, but again, if you are looking for "better than perfect" I can't help you there and I would need to get a dictionary to see what that means.
Going back to the OP, I personally do not see a major difference between a well implemented Class AB and Class A amp. Either can have the "sweet" mildly distorted sound you are looking for or be "brutally honest".
There is also lot of junk out there, on both sides and I suspect you found more of it on the AB side because there are more of them produced.
The new JFETs are a total different product based on silicon carbide. They tolerate very high junction temperatures and switch some stupidly high current and voltage depending on the application. United Silicon Carbide makes them.
The Sony and Yamaha VFET amps don't NEED all that extra circuitry around them to get a great sound out of them. That's already been demonstrated. Just sitting there they're already 10 times more linear than a MOSFET. Power JFETs are those weird one-off parts like the one-off super-car.
There are two problems(?) that plague amps so far as I can tell. One is people demanding more power than they'll ever use, and that leads to the problem of additional stages and complexity. That tends to produce complex distortion. Complex distortion doesn't sound good. I don't need more power than what I've got. My amp has 3 resistors and 4 transistors in the signal path. I definitely feel that less is more. The results are very hard to argue with.
The Sony and Yamaha VFET amps don't NEED all that extra circuitry around them to get a great sound out of them. That's already been demonstrated. Just sitting there they're already 10 times more linear than a MOSFET. Power JFETs are those weird one-off parts like the one-off super-car.
There are two problems(?) that plague amps so far as I can tell. One is people demanding more power than they'll ever use, and that leads to the problem of additional stages and complexity. That tends to produce complex distortion. Complex distortion doesn't sound good. I don't need more power than what I've got. My amp has 3 resistors and 4 transistors in the signal path. I definitely feel that less is more. The results are very hard to argue with.
ghamilton
Super Member
I agree. Go with A/B.
FinalVinyl
Active Member
You noticed those switchable A, A/B amps didn't last long. All it did was cook the electrolytics. An amp getting that hot was ridiculous
it is possible that some of them have insufficient cooling....for using Class A continuously
The Pass Labs XA25 class A amp is close to being the best SS amp that i have ever heard at any price. The secret to a good class A amp is break in time and warm up time. My XA25 took 120 hours too open up and it needs an hour of warm up time to sound it`s best much like a good SET amp. I`m a SET guy but when i heard the XA25 i just had to buy one for another system that i`m building.
I've got a pair of F5 monoblocks which are the same basic topology as the XA25 and they sound amazing. I've never heard a class AB amp that comes close to them.
RobRoy
It's just stuff - but fun
All I use now is those Crown XLS amps. A big one for my bass, and a really big one for my PA. For live stuff it was all about the weight. But I tried it out for home stereo, and it's great. Heck, it even has built in shelving and crossover settings. I turn on the high pass filter at 50 hz and use a sub for the low stuff and it's fabulous.
I still have all my old 70's separates systems, but they are there mostly for looks, like the cars in Jay Lenno's garage. The class D is my "daily driver".
RobRoy
It's just stuff - but fun
I wear hearing aids. They all sound the same to me.
