I love class A sound but compromise by using a current dumping design, which has higher power output and the same sweet sound without the massive current consumption. I could build a 100 or more likely 50 watts class A amplifier no problem and I could afford the electricity to run it. The reason I don't is that it would be big and as I live in a normal size house I dont want the extra heat.
My Audiophile Reason To Avoid Class-A?
I'm not avoiding class-A. Why not exclusively use class-A? Money and/or quality.
I have calculated that with class-A amplifier I need to pay at least $15 per month for the electricity bill. This is based on the "on" time (almost 24x7 for me) and the power wattage of the amp...
I have learned from experience that for an amp to be able to give that "impact" (with standard speaker), the amp has to be "rated" at least 60W. This is very high for class-A. I have only built the Moskido amplifier, that falls within this power criteria (Next is Aleph-J, around 30W)...
That's for the money. Now for the quality. Even with sensitive speakers, simple class-A amps have trouble in bass area due to low damping. This triggers fatiguing distortion, faster than the fatigue due to 2nd order distortion, which is not small in class-A amplifiers...
Basically I choose based on specifications, not whether it is class-A or class-X. So far, no class-A amplifiers (within my reach) fulfills my criteria. (No other classes either hehe). There is the Extrema 100W class-A, but from the threads that I follow, it is not 100% stable. I don't know with the PGP, I don't easily trust amplifier designers
I'm not avoiding class-A. Why not exclusively use class-A? Money and/or quality.
I have calculated that with class-A amplifier I need to pay at least $15 per month for the electricity bill. This is based on the "on" time (almost 24x7 for me) and the power wattage of the amp...
I have learned from experience that for an amp to be able to give that "impact" (with standard speaker), the amp has to be "rated" at least 60W. This is very high for class-A. I have only built the Moskido amplifier, that falls within this power criteria (Next is Aleph-J, around 30W)...
That's for the money. Now for the quality. Even with sensitive speakers, simple class-A amps have trouble in bass area due to low damping. This triggers fatiguing distortion, faster than the fatigue due to 2nd order distortion, which is not small in class-A amplifiers...
Basically I choose based on specifications, not whether it is class-A or class-X. So far, no class-A amplifiers (within my reach) fulfills my criteria. (No other classes either hehe). There is the Extrema 100W class-A, but from the threads that I follow, it is not 100% stable. I don't know with the PGP, I don't easily trust amplifier designers
Like F5? Yes, it's good, especially for the bass, the PP and FB seems like a necessity. For the wattage I need, it would be F5 Turbo. Or some of the BA series.
I think Class-A's bass response is affected a lot by the woofer choice. Depends on the impedance curve and efficiency of the woofer, bass can be surprisingly good with Class-A. Class-A would not be the first choice for who prefer very tight bass, though.
BTW, SE Aleph's DF is high, but it is still sensitive to the impedance load.
BTW, SE Aleph's DF is high, but it is still sensitive to the impedance load.
Aleph current source has that feedback resistor that when removed turns the amplifier into a common SE amplifier (less damping but sound cleaner).
The problem with "old" Aleph amps is the input transistor (IRF610). The input capacitance is still not low enough to make a good treble.
Damping is equivalent of Zout. Output impedance of a Mosfet is an inverse function of its transconductance (1/gm). There are better Mosfets (higher gm) than the stock IRF240. Input capacitance is less an issue in a source follower configuration.
Aleph-J is where the input stage has been improved from IRF610 to a JFET. In my implementations I have used better mosfets than IRF240.
Are some people confusing Class A (which can be push-pull followers i.e. low impedance output) with simple single-ended collector/drain outputs (which must be Class A, and have high impedance output without feedback)?
Other things being equal, a Class A push-pull follower output is likely to have lower output impedance than the corresponding Class AB version.
Other things being equal, a Class A push-pull follower output is likely to have lower output impedance than the corresponding Class AB version.
Damping factor is often over-rated as the cause of this. In a room where bass reverberates, and as with regards to perception, the Q factor of a woofer system is relatively insignificant after it is corrected. Ie, if the level isn't right it might sound that way.
It has been my understanding up until now that a class A amp dissipates max power at all times regardless of the volume it is playing at.
Consequently the Pass amp mentioned by the OP draws 750W not peak but permanently.
Also it is a monobloc so you will need two of those equalling 1500W.
If you play your music at 'normal' levels say around 1W per channel those amps have the same effect as a 1.5kW space heater. Not something I'd like to endure during summer.
On the plus side the louder you play it the less waste heat is produced.
(Btw these Pass amps cost about $20 000 in the US per pair)
I'm currently using 1.7kW of amplification in my stereo, if I would replace my amps with class A jobs I might as well move into a finnish sauna permanently.
Consequently the Pass amp mentioned by the OP draws 750W not peak but permanently.
Also it is a monobloc so you will need two of those equalling 1500W.
If you play your music at 'normal' levels say around 1W per channel those amps have the same effect as a 1.5kW space heater. Not something I'd like to endure during summer.
On the plus side the louder you play it the less waste heat is produced.
(Btw these Pass amps cost about $20 000 in the US per pair)
I'm currently using 1.7kW of amplification in my stereo, if I would replace my amps with class A jobs I might as well move into a finnish sauna permanently.
In My experiences.. My firstwatt does a better job of Bass than a decent (US designed /built) Lm3886 Gizmo managed and Far better than a Paired set of Arcams, which were Claimed as AB.
No need to mention the Farty bass from my Meshplate SE 45 contraption.
One Does need 'quality' highish eff speakers though.
Can't soar like an Eagle if surrounded by Turkeys
Reason for avoidance? Dunno, fear of the unknown..superstition perhaps?
For decades I thought they were Flea Power affectations, more heat than sounds.
Reality is markedly different; Exquisite sound reproduction at the expense of warm heatsinks is proving a V small price.
Power is 7 cents a watt hour where I live.
My espresso machine uses more power than My amp does.. by a Lot.
Unlikely one could even Warm let alone heat their room..Mine can't.
IMO anyone who leaves their Amp on 24/7 has issues beyond their pore Audio system.. simply not credible.
I would have tried A decades ago.. if not constrained by my naive beliefs.
One can easily lead a horse to water... good luck with the rest tho.
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Audio is full of subjectivity. I call it preference. "Better job of bass" or "better bass" is subjective. Some people prefer high fidelity, which is rather objective.
Some of us really like to listen to music. Nothing wrong with 24/7. But I leave my 40W soldering iron on 24/7. Now that is not credible
I have used class-A more than 2 decades ago... I was also constrained by my naive beliefs... hehe just kidding
Here it's closer to 40c, depending on the time of day. Most expensive in the world, some say. It's not like everything is expensive, electricity here is a financial enigma. Maybe the vast network of poles and distance, maybe the recent privatisation of some of the network, maybe the outlandish thoughts of selling the poles to the chinese. A person wants to go out on their own and follow the wind, sun, geothermal...
I pay 10.31p per kWh from a UK supplier who only buys from renewable sources.
Green & cheaper = win/win
As for amps mine are AB but once and almost by accident I had a lengthy phone chat with the amps designer and these amps run the first 20W or so in class A. So you could say they are 20W class A amps with an additional 12dB headroom before clipping.
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The same line of reasoning applies to other things. I'm mulling a copper tubing permeability FM receiver with tubes and with big coils and PCB's, contrarily to the enormous majority of varicap and synthesized minute FM tuners. This is the RF tuned circuit, still under development.
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