Class A Solid State vs Class A Tubes?

[watchnerd]

If operated within their optimal operating envelope, should one expect an audible difference between solid state class A and tube class A into real world, non-pathological speaker loads?

 

[DVDdoug]

It depends on the specifics of the circuit design. It's possible to make a good or bad design in almost any configuration. It's easier & cheaper to make a good amp with modern electronics.

IMO - Tubes are "dumb" (for the last 50 or 60 years) except maybe if you are guitar player and you like the way the particular amp sounds when overdriven into distortion. And class-A power amplifiers are also "dumb". It's OK for a preamp or other low-power circuit where power output and power efficiency are not important.

 

[watchnerd]

It depends on the specifics of the circuit design. It's possible to make a good or bad design in almost any configuration. It's easier & cheaper to make a good amp with modern electronics.

IMO - Tubes are "dumb" (for the last 50 or 60 years) except maybe if you are guitar player and you like the way the particular amp sounds when overdriven into distortion. And class-A power amplifiers are also "dumb". It's OK for a preamp or other low-power circuit where power output and power efficiency are not important.

So is that a 'yes' or a 'no'?

Sounds like you're saying 'yes, you should expect an audible difference', depending on the circuit.

 

[MaxwellsEq]

If operated within their optimal operating envelope, should one expect an audible difference between solid state class A and tube class A into real world, non-pathological speaker loads?

Theoretically, you should be able to build Class A amps used any active device such that they are measurably identical and sound identical. The active device (BJT, FET, tube) should not be audible if done perfectly.

All design is a compromise, however. Solid State allows designers to deploy a relatively high component count, which allows more choices and more ways to actively combat errors.

 

[lashto]

If operated within their optimal operating envelope, should one expect an audible difference between solid state class A and tube class A into real world, non-pathological speaker loads?

most probably no audible differences.
And if any, the differences are nowhere near to what people expect (after they see that the tube THD numbers are ~1000x 'worse'.)

Some measurements from a similar comparison: classic tube-amp vs. modern classD-amp.
The graph-comparison shows that the THD numbers (measured at your ears) are pretty much the same for both amps. And in post6, I tried a bit of math that seems to confirm the same-thd measurements.

 

[mhardy6647]

I would kind of doubt it.
That said, the only vacuum tube amplifiers here that operate in Class A are all single-ended. The soiled state solid state Class A amplifiers here are push-pull.
The harmonic content of the distortion from those two topologies will differ. Audible? Depends.

 

[Purité Audio]

Why would anyone even bother with such inefficient amplifiers , polar ice caps melting, hottest temperatures ever recorded etc etc.
Keith

 

[Schollaudio]

If operated within their optimal operating envelope, should one expect an audible difference between solid state class A and tube class A into real world, non-pathological speaker loads?

Theoretically, no. In reality, yes.

Class A tube amps are typicly simple SE or PP designs with less or no global feedback hence lower damping and higher THD which can make the numbers much higher than that of SS. Some people like that others don't. YMMV.

 

[fpitas]

I would kind of doubt it.
That said, the only vacuum tube amplifiers here that operate in Class A are all single-ended. The soiled state solid state Class A amplifiers here are push-pull.
The harmonic content of the distortion from those two topologies will differ. Audible? Depends.

Class A triode push-pull was popular in the early days of hi-fi and theater, for the relatively low distortion. You don't see it much anymore.

 

[fpitas]

solid state Class A amplifiers here are push-pull.

My J2 has a mu follower output stage

 

[wwenze]

You can make a really horrible transistor amp by using a really simple topology. Pretty sure this reaches the realm of "no ABX needed" and worse than some tube amps.

For all the crap we like to throw on tubes, one thing i still believe is that for certain situations and in very low component count topologies, a tube can still have less distortion than a transistor. But of course once you acquire an opamp IC with a gain of 100,000 and you negative-feedback it until gain = 10 and bloody fast bandwidth all thanks to the magic black box circuit inside the chip package, you get an end result where the output voltage tracks very closely to the predictions according to opamp theory. In comparison a tube or transistor on its own becomes "non ideal" very quickly with just small changes of operating conditions, since even a 1% deviation is -40dB.

 

[fpitas]

You can make a really horrible transistor amp by using a really simple topology. Pretty sure this reaches the realm of "no ABX needed" and worse than some tube amps.

For all the crap we like to throw on tubes, one thing i still believe is that for certain situations and in very low component count topologies, a tube can still have less distortion than a transistor. But of course once you acquire an opamp IC with a gain of 100,000 and you negative-feedback it until gain = 10 and bloody fast bandwidth all thanks to the magic black box circuit inside the chip package, you get an end result where the output voltage tracks very closely to the predictions according to opamp theory. In comparison a tube or transistor on its own becomes "non ideal" very quickly with just small changes of operating conditions, since even a 1% deviation is -40dB.

Just for clarification, that amp is intended for DIY classroom use. Some people do like the sound of them.

 

[fpitas]

For all the crap we like to throw on tubes, one thing i still believe is that for certain situations and in very low component count topologies, a tube can still have less distortion than a transistor.

I wonder how true that is when you intend driving loudspeaker type impedances.

 

[egellings]

If operated within their optimal operating envelope, should one expect an audible difference between solid state class A and tube class A into real world, non-pathological speaker loads?

If frequency response is flat, distortion low, and output impedance is low for both kinds of amplifier, and both are operated well within their power capabilities, then there should be no sonic difference between the two devices.

 

[ta240]

Why would anyone even bother with such inefficient amplifiers , polar ice caps melting, hottest temperatures ever recorded etc etc.
Keith

A low power SE tube amp can run on 90 watts, a typical 20 watt class A amp takes about 200 watts; so should we put limits on how loud people can play their Class D amps so that they don't exceed that power usage?
And don't get me started on how much resources get used making and transporting yet another container ship load of 'cheap' class D amps; or even how the energy is produced to run the factories. Or how much fuel the delivery trucks use taking each one to each person's home. Or how many will end up in landfills shortly. FOMO causing people to continually replace their stuff rather than buying one and keeping it for 20-30 years is possibly having a much worse affect on the planet than someone running a class A amp.

 

[fpitas]

don't get me started on how much resources get used making and transporting yet another container ship load of 'cheap' class D amps

I'll start by saying, I don't have strong feelings one way or another. But would a ship load of cheap class A amps be somehow more ecological?

 

[mhardy6647]

Why would anyone even bother with such inefficient amplifiers , polar ice caps melting, hottest temperatures ever recorded etc etc.
Keith

Absolutely -- and I hope you join me in imploring those same anyones: please, please -- if you're going to use passive loudspeakers, go high sensitivity.
e.g., 84 dB SPL per watt at 1 meter vs. 104 dB SPL per watt at 1 meter: 20 dB higher sensitivity means one-one hundredth of the amplifier power requirement.
Hmmm... perhaps Altec painted their drivers green for a reason?

 

[lashto]

You can make a really horrible transistor amp by using a really simple topology. Pretty sure this reaches the realm of "no ABX needed" and worse than some tube amps.

...

apparently, even that "horrible transistor amp" can sound good. From the linked impressions:

“It actually sounds good…” with the caveat of not asking too much from the amp
...
I purchased these kits seven years ago to drive high efficiency compression drivers, which are typically rated at over 113 dB/W/m

 

[fpitas]

apparently, even that "horrible transistor amp" can sound good. From the linked impressions:

True. And as I said, that amp is merely a learning tool, you build it yourself as your first amplifier at Pass' Amp Camp.

 

[RayDunzl]

Why would anyone even bother with such inefficient amplifiers , polar ice caps melting, hottest temperatures ever recorded etc etc.
Keith

Because (maybe) they bought one in the dim and distant past, and it still works?


"The New Allnic T-1500 300B Single Ended Integrated Amp. Fully CE and ROHS compliant"

"A-6000 Monobloc Power Amplifier The A6000’s are quadruple parallel single ended monobloc amplifiers"

"The Sugden Class A, IA-4 Integrated and the SPA-4 Stereo Power Amp ,are two of the finest amplifiers we have heard, at any price."

Wayback Machine

web.archive.org

Global warming isn't "new", it's just getting more press, and becoming its own marketing tool.

Scientists clarify starting point for human-caused climate change

Scientists have clarified the starting point for human-caused climate change to be actually the early 1800s when green house gasses started warming oceans.

www.carbonbrief.org

"Greenhouse gases began warming the world’s oceans in the early 1800s, decades earlier than previously thought, according to a new study."


< has old Class A Krells, used sparingly, when the little speakers won't cut the mustard.