Champions of Class "A"

cmalak said:
Class A SS:

Class A SS:

Pass Labs
Accuphase
Gryphon
Lamm (M1.2...100wpc Class A with tube input driver)
Luxman
Monarchy Audio
Musical Fidelity
Plinius
Krell (old school)
Boulder
Threshhold (precursor to Pass)
Halcro
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Cyril, I was wondering when someone would mention Plinius, they were a hell of an amp in the early days, still are for that matter.
 
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Yes Indeed any best of --

you cannot leave out the venerable Electro Research A75 Amp

I had two of them BiAmped into Snell AIII's--boy could they Boogie OOOOOh yeah!!

Bruce




Snell_A_001.jpg
 
Class A amps can further be categorized as fixed bias (or pure class A) and adaptive bias. Boulder is adaptive bias. So were the Krell FPB and KAS series.
 
A little bird told me there was a thread about Class A, which of course is so near and dear to my heart. How are the folks on the Shark today? My 2 cents is that: 1. This would have to be focused on solid state amps as correct me if I am wrong but most tube amps are closer to Class A by design than not? I have very little experience with tube circuits so forgive my ignorance. 2. Adaptive bias is not really Class A as there is a frequent transition state for the devices, and in my experience this negatively affects the sound. To that end the products that use/used adaptive bias may actually sound better if that circuit were eliminated. Even dear old dads monsters from the past using adaptive bias would have been better without it. He and I have discussed this many times... But from a marketing standpoint it sounds much better to have Class A in the description and save a huge amount of space using smaller heat sinks. So that being said, we can eliminate many from the list and add BSC because even though my company is only 4 years old I have had only Class A amps from the start and don't plan on going anywhere for the next 15-20 years or so. :) I still contend the biggest and baddest of all the Class A amps is the KRELL KRS-200. I don't think anyone has come close to surpassing this Fixed Class A monster. I do have plans for a 7 series amp that in concept will better the KRS-200, but it is time, budget, and market dependent. I also agree Nelson Pass designs to be #1 as he was one of the first and continues to deliver fine Class A products, but Krell shouldn't be #9 as the first 15 years of its existence were based on Class A designs. Definitely Gryphon and Accuphase are greats on this list, the 1st Levinson 25 watt class A ML2 should be an honorable mention, good amp!. Also some Class A efforts from Bedini and Belles which I believe had good sounding Class A SS amps.
 
Champions of Class "A"

Hi Brett...I shouldn't have put numbers to suggest an order. I was simply enumerating and in no way suggesting that this was in descending order of any kind. That would be simply silly as there is no way to make an objective comparison of similar amp designs to begin with and even if there was it would only be one person's opinion in their particular test system. So again no order being suggested. I will go ahead and edit my post and take out the #s.
 
Re: Champions of Class "A"

cmalak said:
Hi Brett...I shouldn't have put numbers to suggest an order. I was simply enumerating and in no way suggesting that this was in descending order of any kind. That would be simply silly as there is no way to make an objective comparison of similar amp designs to begin with and even if there was it would only be one person's opinion in their particular test system. So again no order being suggested. I will go ahead and edit my post and take out the #s.
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+1
 
Thanks Brett for the insights on class A amps. In my limited experience I find the class A ss amps to sound faster than the sliding bias class A amps. I suppose having the transistors always on at full power might have something to do with this.
 
Brett,

Looking forward to your S5 amp. One of my dealers is eager to get his for demo.

BSC

DSC02378r.jpg
 
Mike said:
Hi Bret - tweet tweet.....good to see you back.
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Good to be back, just finished the last go around with the L5 Preamp and anxious to get these to my dealers in the next few weeks, details forthcoming. Now I can take a deep breath before I jump into the I3 and I5 integrated amps.
 
If we aren't referring to high dollar items?, I'd have to give a shout out to Sudgen in the UK, whom I think were one of the first companies to use class a in their designs during the 60s/70s:

J. E. Sugden Class A amplifiers - The 1960s and 1970s

Another nice sounding brand was Forte from the 80s, which was an outshoot of Threshold as I recall. I'm sorry to come across as a troubler, if I do?, it's on,y because I see/hear things/components at both ends of the cost range, as a means to assist friends along the ways, as I once worked as a buyer for a few audio shops here in Michigan, back in the day, I've always felt it important to know which stuff was musical regardless of cost!, we of course had ones with deeper pockets and serviced their needs, but we never forgot about the average joe sorts either, it's more universal then merely catering to the wealthy, and overlooking the needs of the few.


I'm used to associating with the rich, as well as the not so well off, but in the end, to me it has always been about finding something to fit a friends requirement regardless of which!, I've heard the extreme, but in the same listening sessions, have heard cheaper items that can hold their own as well, I'm not here to challenge anyone, yet I do think about the small guys as well.
 
The Forte model 4a is said to be a very good amplifier at 50w/ch class A. I have a Forte model 5 (along with a model 2 preamp) which is class AB 200W/ch. A good amp but I don't think as good as the model 4a.
 
The Valvet A3.5 monoblocks are very nice 50w Class A amplifiers using a single pair of transistors and with no negative feedback- $6k list, so a bargain.
 
BretDago said:
.....2. Adaptive bias is not really Class A as there is a frequent transition state for the devices, and in my experience this negatively affects the sound......
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KeithR said:
Bingo- a lot of "class a" amps on this thread really aren't.
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Hi All,

I thought I would chime in here.

I am glad that this topic regarding class A amps has been brought up, because I have often wondered why there seems to be a disconnect between fixed class A bias and variable class A bias. Companies like Gryphon, Plinius and BSC Audio, that produce fixed class A bias amps have a manual user selectable switch that allows you to go into high/low bias class A/B and, unlike variable class A bias amps, is a separate control that when bypassed does not effect the amp's full class A rating. With variable class A bias amps that claim class A, it is hard to tell how much class A bias (if any) is implemented and whether it is even truly near its rated power.

In response to Bret D'Agostino's earlier post, I agree that there seems to be an effect on the sonic performance of variable class A bias amps because of the transitioning bias which inevitably points to the transistors turning on and off frequently and therefore the transistors are not being allowed to "settle" into a steady state. In addition, when I look at fixed class A bias amps like Gryphon, Pass Labs, old Krell, BSC Audio, etc., they obviously have very large heatsinks which seems to me to be a basic requirement in an air-cooled design. I have to question the heatsink size on variable class A bias amps as to whether they have very much class A at all, compared to that of fixed class A bias amps. Of course I am not an engineer or technically inclined, so I hope that Bret will chime in about what I have said, just in case I am speaking out of turn.
 
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