There are very high powered pure class A amps. Needless to say they are typicaly very expenisve, very big, very heavy, run very hot and are costly to operate. |
I could be very wrong about this, but, I thought Aragon's trick was that they offered their rated class A opperation only so long as they were driven into an 8 Ohm load, below which they reverted into class AB. From what I understand the best ss class A/AB amps half their class A output as their class AB output doubles into progresively halved impdedances. |
Unless I missed something, everything in these aritcles suggest that the Krell's are capable of maintaining Class A operation as they double down, but, they don't actually make that claim. As for me, I believe they do. Wretched excess? I love it! I may be part of the minority here on Audiogon, but I really like the "real" Krells and thats based on what I've heard not on what I've read. Though it is pretty impressive reading. |
Chuck, I was under the impression that some particular examples of the Aleph amps with minimal gain stages were unable to double down, but, all the other Pass amps were able to double down. I would guess that those which could/can doube down would halve their class A out-put as they did so. |
Hi Chuck, thanks for the update. I went to the Pass site. I didn't see anything about power into lower impedances, but, you may very well be correct. There was mention of the XA series not having the current delivery of the X series and that the XA's using only two gain stages like the afore mentioned Alephs'. |
Chuck, thanks. It's interesting that Pass suggests that "These are not design oversights or flaws in the XA-200, but rather a condition of the very highly biased Class A operation." I don't recall this "reasoning" from some other Class A amplifier manufacturers. It may even contradict what is commonly percieved as techincally available from Pass' previous designs. |
Onemug, Jon recently told me the same thing re: a different Class A/AB Threshold amp. |
Real Krells can double down and down again from their rated power. I'm not sure if they maintain full Class A operation as they do. I sure would like to find out though. |
Moribus, thank you. That really clarifies it. Am I correct in assuming that power increases by ss amps into lower impedances is not determined by Class of operation? |
Chuck, all early Krell's were Class A. Some newer ones (IMHO the only real Krells) are as well, but, use their proprietery sliding bias scheme. I still think these sliding bias amps can make good on their Class A claim. The very early Krells used fans, the later ones used massive heat sinks and the newer ones sliding bias, (still pretty hefty heat sinks as well). |
I'm pretty sure its push pull. Other than Pass and Monarchy I don't know of any other single ended Class A solid state amplifier manufacturers. |
Chuck, even single ended Class A amps are capable of respectable power out-put. The solid state single ended Class A Pass Aleph 1's power ratings: 150 Watts > 8 Ohms, 300 watts > 4 Ohms, 600 Watts > 2 Ohms. Of course these amps were expensive exceptions to the norm. The less expensive Monarchy solid state SE 100 single ended Class A power amps power rating: 100 Watts > 8 Ohms, 200 Watts > 4 Ohms. The Monarchy hybrid tube/solid state single ended Class A SE 160's power rating: 160 Watts > 8 Ohms, 320 Watts > 4 Ohms. Needles to say I can't personaly verify these quoted ratings. There does seem to be some confusion about Monarchy's most recent 250 Watt Class A/AB hybrid's power ratings. |
I shouldn't have singled out Monarchy for "confusion" with re: to rated power out-put. One of Pass' amps failed to achieve rated power during a test by Stereophile. |
Chuck, I think your right about single ended amps being less likely to produce as much power as push/pull, but, when it comes to solid state the differences aren't as great as in tube amps.......
I'd still like to know if those ss amps that are touted as being pure Class A and being capable of doubling down, maintain pure Class A operation as they double down. |
Onemug, may have a point. Bear with me for a moment and forget the "most speakers are damaged due to being under powered rather than to being over powered". What if a speaker manufacturer refused to honor a waranty because one used amplifiaction that was rated within the speaker manufacturers standard 8 Ohm limits but actually exceeded its 8 Ohm rating? |
Atmasphere, thank you. I was aware of the above. I think your point about amps increasing power not necessarily being a good thing is well taken. As you well know as an amp may increase its power out-put into lower impedances, it will also decrease its power out-put into higher impedances. As you pointed out with some speakers that vary a great deal in impedance load this will have a rather negative effect. On the other hand speakers with steady low impdeance loads will benefit from such an amp. Once again its about using the right tool for the job at hand. |
It depends on the amp. In theory if it is a solid state amp we would hope to see 600 Watts @ 3 Ohms if the amp is rated as 200 watts @ 8 Ohms. This generally doesn't apply to tube amps. Not all (in fact few) amps are capable of this kind of power delivery. Don't assume an amp is capable of this. |
