Hear here , hope to learn alot more about class D, aside is their a Tooby Amp you can recommend ..??
Regards
I think so. Admittedly, my predilection for tubes is based on playing through 100+ guitar amps over the past 40 years, which maybe doesn't translate. Don't get me wrong, to me, nothing beats a Roland JC 120 at what it does, and it's an awesome sound--just not what I'm looking for. Nor am I looking for a wooly beast with 40db of hum (though I dig that in a '59 Fender Bassman). My current amp, a Marantz 2270, is a wonderful solid state amp, but I'm dumping my very meh 901s and am taken with the vintage Klipsch shtick, and I've read (over and over) that they like tube amps. So, if you were to indulge a nostalgic twat and recommend a tube amp, what might it be?
OK here's the skinny. The sound that any amplifier has is caused by its distortion spectra and how the distortion behaves over frequency. If the distortion rises with frequency this is likely to cause the amp to sound harsher and brighter, and is a problem that most solid state amps made prior to 2005 or so had. Many still have it today.
Tube amps have more distortion overall but the distortion they make tends to be the lower orders, the 2nd and 3rd, which are innocuous to the human ear. But they can mask higher orders and because tubes generally tend to have less feedback, the distortion rising with frequency thing is less of a problem (but its still there).
So the fact that tubes sound nice and smooth because the lower ordered harmonics are masking the higher orders is what has kept tubes in business the last 64 years since being declared 'obsolete'. Clearly the declaration was premature!
However if you were reading closely one fact is apparent: the sound of the amp is in fact its distortion signature. What this means is that if you can have two different amps with the same signature, they will sound the same. So that's where class D comes in, because its possible to get a class D amp to sound very much like tubes. If the circuit is properly designed, the non-linearities in the amp will result in lower ordered harmonics. Its also possible for class D amps to have simultaneously very high amounts of feedback yet still get that ruler flat distortion vs frequency curve I mentioned, which is far more important than the old 'THD' spec, which tells you almost nothing about the sound of the amp.
Just so we're clear about Distortion vs Frequency,
all zero feedback tube amps have a ruler flat curve across the audio band.
Also FWIW: the Marantz 2270 is a classic 70s Japanese design (I've serviced many of them) but it has the distortion rise problem. Just so you know. Any solid state amp that old does!
I can go into depth about how class D amps can sound like excellent tube amps if you need more technical information. Its also important to know that not all class D amps sound the same just like not all class A amps sound the same, since distortion is what causes their sonic signature.
The technology should support the sound of what we here such that it sounds like music rather than electronics.
My speakers are 98dB and 16 Ohms, designed for tube amps but I don't miss the tubes at all running my class D amps on them- I get the same smooth mids and highs with the same musical involvement- and its easier to make out details like vocals, room ambience and so on.
But since some people seem peeved about such things being said, here are some tube amps to consider well within your price constraints:
1) Refurbished Dynaco Mark 4s: these are monoblock versions of the classic Dynaco ST70 and don't have the reliability problem of the tube rectifier. 35 Watts/channel. They are rare and will need refurbishment (power supply filter capacitors and the like replaced)
2) Refurbished or new Dynaco ST70. A classic amp; the weakness is they should have had dual rectifiers for reliability.
3) Refurbished Dynaco Stereo 35. This amp is 17.5 Watts/channel and a bit more linear than its bigger brothers with wider bandwidth and lower distortion.
4) Refurbished Harmon Kardon Citation 2, another solid classic, perhaps one of the best tube amps from the glory days of tubes. 50 Watts/channel, perhaps more than you need but a very solid performer and works well on the Klipsch.
5) Any RM Labs (Roger Modjesky) amp, such as the RM10. Might need refurbishment depending on age. Roger (RIP) passed away a few years ago and was one of the few
actual engineers building tube amps for high end audio. His designs are supported by Electra Fidelity.
6) Manley EL84 amps. Well supported and nice construction.
With your speakers you really don't need a lot of power. Its a simple fact that the smaller the tube amp, the more likely it will be to sound better. This is mostly due to the output transformer having wider bandwidth if designed for lower power.
I would stay away from SETs. They only make about 20% usable power as opposed to 95% usable power of a good PP amp. If you push them past that 20% level, they start to sound 'dynamic' due to how the higher ordered harmonics showing up on transients interact with the ear (which uses higher ordered harmonics to tell how loud sounds are). Its really just distortion masquerading as 'dynamics'. You'll find (as I did) when you have cleaner power its more likely you'll use it- its the mark of the best systems that they don't sound 'loud'.
