Re-imagining "Class A" Amplification

[MarkusBarkus]

...I wouldn't say it's confusing. And no, I don't own those amps, but I find the technology interesting, and look forward to hearing them soon.

 

[SeagoatLeo]

Thats funny I have a Pure Class A amp and experience NONE of what this ridiculous article asserts, the soft bass and lack of transparency you're quoting here. Before you shill for Gary ( I get it he's a nice guy) and Westminster know what you are talking about....Nothing on the market today truly replaces pure Class A amplification, I don't care how you want to market it, it simply doesn't. It's a matter of system building around the sound you get anyway, I get all the transparency I want from my Preamp (Ref6SE), and details from my dac (Totaldac Triunuty), and sense of space, and soundstage from my Streamer (Pulsar), and pure bliss from my amplifier (Sugden FBA 800), whcih is Pure Class A. Hot and inefficient, and absolutely LOVELY in it's sound presentation.

Marketing an amp as a replacement to Class A, or Class A thats better, reimagined whatever, is simply ridiculous. It's biased Class A, not Pure Class A... It's either Pure Class A or it's not, there is no in between.

Well for the past 18 years I owned and occasionally used an EAR 890. That's "pure" Class unless you dismiss it because it uses a kinkless triode configuration (so I've read). Also, I had a integrated Yamaha amp back in the 1970s which had "pure" Class A switch. The former was quite good but lacked once hearing the Reis, it was obvious which one is the superior amp and not just powerwise. My highly modified voltage regulated Dynaco ST70 and mono-blocks had superior dynamic range and bass. The latter integrated probably had too few watts and sounded very nice but for the dynamics which sounded compressed, lack of deep bass, etc. I agree with @viola. I don't care if it's not "pure" Class A or Class H or Class Z. The Reis are amazing!

 

[skids929]

Well for the past 18 years I owned and occasionally used an EAR 890. That's "pure" Class unless you dismiss it because it uses a kinkless triode configuration (so I've read). Also, I had a integrated Yamaha amp back in the 1970s which had "pure" Class A switch. The former was quite good but lacked once hearing the Reis, it was obvious which one is the superior amp and not just powerwise. My highly modified voltage regulated Dynaco ST70 and mono-blocks had superior dynamic range and bass. The latter integrated probably had too few watts and sounded very nice but for the dynamics which sounded compressed, lack of deep bass, etc. I agree with @viola. I don't care if it's not "pure" Class A or Class H or Class Z. The Reis are amazing!

I am not questioning the quality of the amps or how much you prefer them over something else- I am sure they're wonderful. But I would certainly hope they sounded better than an amp from the 1970s. I am just taking issue with the marketing message. These are class AB switching amps, and they do NOT sound like Class A amplification, at all. Listen to Riviera or Sugden, and you will hear Class A sound if you care to do so, and then hear the difference in your amps that have somehow reimagined Class A.

Class A for all it's limitations of wattage, heat, and pricey is the most linear way to listen to an amplified signal. What that means to you and whether it's better or you prefer it is a different discussion. Listen to what you like, as long as we're clear on the difference and that those Westminster amps are AB switching amps and/or biased to AB.

 

[SeagoatLeo]

I am not questioning the quality of the amps or how much you prefer them over something else- I am sure they're wonderful. But I would certainly hope they sounded better than an amp from the 1970s. I am just taking issue with the marketing message. These are class AB switching amps, and they do NOT sound like Class A amplification, at all. Listen to Riviera or Sugden, and you will hear Class A sound if you care to do so, and then hear the difference in your amps that have somehow reimagined Class A.

Class A for all it's limitations of wattage, heat, and pricey is the most linear way to listen to an amplified signal. What that means to you and whether it's better or you prefer it is a different discussion. Listen to what you like, as long as we're clear on the difference and that those Westminster amps are AB switching amps and/or biased to AB.

So, I've been stupid not hearing the superior Riviera Labs AFM100 Special Edition mono amps at $82,500 (which I cannot afford) or the the Sudgen Grande mono amps at $31,000 (about the same Rei pairs). EAR 890s are from about 2000, not 1970s. Thank you for informing me about a product I did not know about (Riviera Labs) despite my inability to purchase it and how I've cheated myself out of a superior amplifier in the Sudgen. You should help all of us at WBF with new forums on Riviera Labs and Sudgen. Maybe some other members have experience and own these superior "pure" Class A amps and want to comment.

 

[KeithR]

I've auditioned Sugden and didn't find it as compelling as the REIs. I also preferred the REI to Gryphon Essence in my rig. I've owned the baby Pass XA25 and auditioned the SIT-3 (which many consider his best) and the former is possibly the most overrated amp I've owned. The latter is a great amp but you need 100db speakers. YMMV.

So excuse me when the "Class A purists" come around and talk trash.

 

[skids929]

I've auditioned Sugden and didn't find it as compelling as the REIs. I also preferred the REI to Gryphon Essence in my rig. I've owned the baby Pass XA25 and auditioned the SIT-3 (which many consider his best) and the former is possibly the most overrated amp I've owned. The latter is a great amp but you need 100db speakers. YMMV.

So excuse me when the "Class A purists" come around and talk trash.

Which Sugden did you audition? And no one is talking trash so take it easy Tiger. Not trying to shatter your world here or make amp comparisons..Congrats your $30k+ amps beat a $5k Pass Labs amp. Feel better now? lol

 

[seatrope]

i only see one person coming in here guns blazing, in their first post accusing @CKKeung of being a “shill for Gary” when all he did was post excerpts from a formally published review and none of his own comments.

Said reviewer has probably listened to his share of pure Class A amps, me thinks.

 

[skids929]

i only see one person coming in here guns blazing, in their first post accusing @CKKeung of being a “shill for Gary” when all he did was post excerpts from a formally published review and none of his own comments.

Said reviewer has probably listened to his share of pure Class A amps, me thinks.

Zero guns involved, just dissenting opinion which is apparently blasphemy here..Glad to see you are so easily taken by a reviewers comments, as long as you understand how they acquire the gear and how the industry works. I've heard both as well and my share of Class A. My point is sound, these may be great amps, they are NOT Class A amps. And again, they DO NOT sound like them either, I've heard them. Posting excerpts from favorable reviews putting down a technology that these are posing to be, is shilling when it benefits the manufacturer btw.

People need to make informed decisions, these amps aren't rethinking anything that hasn't already been done. It's just biasing, and therefore not Class A, it's Class AB. Enjoy your amps, or preamps whatever you bought. I am just here to shed light on the truth.

 

[LL21]

Zero guns involved, just dissenting opinion which is apparently blasphemy here..Glad to see you are so easily taken by a reviewers comments, as long as you understand how they acquire the gear and how the industry works. I've heard both as well and my share of Class A. My point is sound, these may be great amps, they are NOT Class A amps. And again, they DO NOT sound like them either, I've heard them. Posting excerpts from favorable reviews putting down a technology that these are posing to be, is shilling when it benefits the manufacturer btw.

People need to make informed decisions, these amps aren't rethinking anything that hasn't already been done. It's just biasing, and therefore not Class A, it's Class AB. Enjoy your amps, or preamps whatever you bought. I am just here to shed light on the truth.

Big fan of Class A myself, having owned Gryphon amplification for over a decade (Antileon, then Colosseum, then Mephstio). and now again with Robert Koda K160s which are 235 pure Class A into 4ohms.

I suppose the other behemoth name in this discussion is going to be the big Boulders. Here is how they describe their design. Do you consider this A/B because it is Class A with "adjustment" to bias? The front of their Technical Information document clearly focuses on Class A as you can see in the image, and the information in the technical document clearly insists it is operating in Full Class A and differentiates itself from other sliding bias designs.

"Full Class-A biasing to maximum output [2100 watts into 8ohms], managed with an analog circuit that reduces bias current whenever possible to increase efficiency and reduce heat"

"Bias operation is Class A to full rated output power. An analog bias circuit continually monitors the voltage draw, current draw and load to adjust the bias current as necessary in order to maintain Class A operation. If a musical transient requiring more bias current is detected, the circuit will raise the bias much faster than the audio signal to keep the amplifier operating within the Class A window. After the transient has passed, it will then gently lower the bias in a decreasing analog manner over a period of 28 seconds until another transient peak is detected. This has the benefit of keeping the 3050 operating in full Class A mode without the drawbacks of massive power consumption excessive heat generation and the audible steps or “sliding” of other active bias management systems."

Boulder 3050 Mono Amplifier - 3000 Series - Boulder Amplifiers

The Boulder 3050 Mono Amplifier, our flagship, is our largest, most powerful, and most luxurious product in over 30 years of sound system design.

boulderamp.com

 

[MarkusBarkus]

...while offering less printed info than Boulder, my luscious Luxman m900 amps note:

"For M-900u, up to 12 W of the output is operated with pure class A. In this case, the meter reads -10 dB or so, and the inclusion of almost all of the ordinary volume range balances between high power and dense sound quality with pure class A."

I expect to be listening to a WestminsterLabs set-up this time next week, and can report back to you naughty audiophiliac boys with any "impure" thoughts that may arise.

 

[skids929]

Big fan of Class A myself, having owned Gryphon amplification for over a decade (Antileon, then Colosseum, then Mephstio). and now again with Robert Koda K160s which are 235 pure Class A into 4ohms.

I suppose the other behemoth name in this discussion is going to be the big Boulders. Here is how they describe their design. Do you consider this A/B because it is Class A with "adjustment" to bias? The front of their Technical Information document clearly focuses on Class A as you can see in the image, and the information in the technical document clearly insists it is operating in Full Class A and differentiates itself from other sliding bias designs.

"Full Class-A biasing to maximum output [2100 watts into 8ohms], managed with an analog circuit that reduces bias current whenever possible to increase efficiency and reduce heat"

"Bias operation is Class A to full rated output power. An analog bias circuit continually monitors the voltage draw, current draw and load to adjust the bias current as necessary in order to maintain Class A operation. If a musical transient requiring more bias current is detected, the circuit will raise the bias much faster than the audio signal to keep the amplifier operating within the Class A window. After the transient has passed, it will then gently lower the bias in a decreasing analog manner over a period of 28 seconds until another transient peak is detected. This has the benefit of keeping the 3050 operating in full Class A mode without the drawbacks of massive power consumption excessive heat generation and the audible steps or “sliding” of other active bias management systems."

Boulder 3050 Mono Amplifier - 3000 Series - Boulder Amplifiers

The Boulder 3050 Mono Amplifier, our flagship, is our largest, most powerful, and most luxurious product in over 30 years of sound system design.

boulderamp.com

View attachment 133342

This is another example of biased Class A operation. Just a different way to design and market it, all of this is a play on words- ALOT of manufacturers do this.. The sheer size of this amp does give it some advantages however, but there are too many variables to know how this amp is being rated. e.g. is the wattage just referring to power consumption or power output etc...Either way a 2100 watt pure Class A amp would burn a damn hole through your floor, it would take much larger heatsinks....Like the size of your house! And the amperage is off when you look at the specs to be Pure Class A.

Like I have said throughout, those amps likely sound wonderful and sounds like they use Class A to deal with transients, something Class A is known to be adept at dealing with since they're always on transisitors. But somewhere in this design there is a switchover with a mostly on transistor, they say it right in the description. It's just a play on words.

read through this thread it Georgehifi does a better job than I do describing it:

Audiogon Discussion Forum

What are the best options in Pure Class A amps above at least 100 watts in 8 ohms? The ones I know of are:1) Pass Labs XA100.52) Pass Labs XA100.8 (and ...

forum.audiogon.com

Also this is a good read on Class A as well, Shens design is similar to what my Sugden has with 4 bridged Class A amps operating, 2 per rail.

clayton audio m300

It's the sheer wattage it takes to run Class A, it's totally inefficient.

 

[skids929]

...while offering less printed info than Boulder, my luscious Luxman m900 amps note:

"For M-900u, up to 12 W of the output is operated with pure class A. In this case, the meter reads -10 dB or so, and the inclusion of almost all of the ordinary volume range balances between high power and dense sound quality with pure class A."

I expect to be listening to a WestminsterLabs set-up this time next week, and can report back to you naughty audiophiliac boys with any "impure" thoughts that may arise.

Again they may sound pure as the driven snow, and for the money I hope they do...But they are not all Class A, and they haven't reimagined a thing. There is entirely too much confusion around this topic unfortunately, and this is the reason why. Coda and Riviera are about the only makers (I am sure there are others I am unaware of) I know who has a bias you can turn on/off, which I think is a really cool feature.

If you want to listen to Class A in all it's glory you buy Sugden, or you buy Riviera if you can swing it, or Firstwatt.

 

[LL21]

This is another example of biased Class A operation. Just a different way to design and market it, all of this is a play on words- ALOT of manufacturers do this.. The sheer size of this amp does give it some advantages however, but there are too many variables to know how this amp is being rated. e.g. is the wattage just referring to power consumption or power output etc...Either way a 2100 watt pure Class A amp would burn a damn hole through your floor, it would take much larger heatsinks....Like the size of your house! And the amperage is off when you look at the specs to be Pure Class A.

Like I have said throughout, those amps likely sound wonderful and sounds like they use Class A to deal with transients, something Class A is known to be adept at dealing with since they're always on transisitors. But somewhere in this design there is a switchover with a mostly on transistor, they say it right in the description. It's just a play on words.

read through this thread it Georgehifi does a better job than I do describing it:

Audiogon Discussion Forum

What are the best options in Pure Class A amps above at least 100 watts in 8 ohms? The ones I know of are:1) Pass Labs XA100.52) Pass Labs XA100.8 (and ...

forum.audiogon.com

Also this is a good read on Class A as well, Shens design is similar to what my Sugden has with 4 bridged Class A amps operating, 2 per rail.

clayton audio m300

It's the sheer wattage it takes to run Class A, it's totally inefficient.

Again they may sound pure as the driven snow, and for the money I hope they do...But they are not all Class A, and they haven't reimagined a thing. There is entirely too much confusion around this topic unfortunately, and this is the reason why. Coda and Riviera are about the only makers (I am sure there are others I am unaware of) I know who has a bias you can turn on/off, which I think is a really cool feature.

If you want to listen to Class A in all it's glory you buy Sugden, or you buy Riviera if you can swing it, or Firstwatt.

Thanks and clear. In terms of pure Class A, I believe then we talking from your list and others:
- Gryphon (Mephisto, Apex)
- Robert Koda (K160 Monos)
- Lamm (1.2 Reference and ML3)
- Zanden (9600 Ref Mk2)
- Aries Cerat
- Riviera Monos
- Clayton Monos
- Sugden
- Coda
- And no doubt many lower wattage pure Class A amps