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commercially available low power class A solid state amplifiers?

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I've been reading about the various DIY plans and kits that implement this kind of amplifier (PASS, Hiraga, JLH 1969, which I have made) i.e. 8 - 20W range - but which commercially sold amplifiers fit into this class, or would be comparable?

 

Just curious - and my usual googling hasn't shown up a great deal.

 

Except this: http://www.ebay.com.au/itm/251547958309 which doesn’t count :D

 

 

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Not sure if you were after DIY, but commercially completed amps with that spec are very short on the ground. I thought there was maybe a sugden that fit the description, this was the closest (more power than requested @50 watts), the rest are Integrated's;

http://sugdenaudio.com.au/?p=64

This is the only one. I know of Within your spec, but it is not cheap....

http://www.telluriumq.com/iridium-20/

Edited by Ray H

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Not sure if you were after DIY, but commercially completed amps with that spec are very short on the ground

 

 

Yes there are lot's of DIIY/kit type options, was just curious about the commercial ones in a similar class (if any).

 

 

This is the only one. I know of Within your spec, but it is not cheap....

http://www.telluriumq.com/iridium-20/

 

also this one, also not cheap:

 

http://www.firstwatt.com/sit2.html

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I've been reading about the various DIY plans and kits that implement this kind of amplifier (PASS, Hiraga, JLH 1969, which I have made) i.e. 8 - 20W range - but which commercially sold amplifiers fit into this class, or would be comparable?

 

Just curious - and my usual googling hasn't shown up a great deal.

 

Except this: http://www.ebay.com.au/itm/251547958309 which doesn’t count :D

 

If you want a low power "fully built" amp (ie. not DIY) ... why wouldn't you go for a tube amp?

 

Andy

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If you want a low power "fully built" amp (ie. not DIY) ... why wouldn't you go for a tube amp?

 

Andy

 

I already have (DIY) examples of both here I'm playing with, this is more about finding similar amps out of curiosity.

 

Valvet Class A E1r monos - (10 w/ 8 ohms) 

 

http://www.highend-electronics.com/16.html

 

Aha.. also while googling for more info on that one I found:

 

Audioprojekte CA10

http://www.audioprojekte.de/html/ca10en.html

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The diy amps you have there from opc might become commercially available yet ;)

(No idea when but its certainly on the cards)

Edited by hochopeper

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Garry Cawsey has designed a solid state Class A amplifier incorporating new topology and improved components.It has passed the prototype stage and is currently being manufactured  in small production runs for field testing.Certainly not having to use an expensive output transformer and pre war inefficient valves is very much in favour of the solid state vs the vacuum designs.

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I build only SE class A valve amps but it would be nice to compare them with a commercial SS Class A. Mine are a lot cheaper. Lol.

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I've been reading about the various DIY plans and kits that implement this kind of amplifier (PASS, Hiraga, JLH 1969, which I have made) i.e. 8 - 20W range - but which commercially sold amplifiers fit into this class, or would be comparable?

 

Just curious - and my usual googling hasn't shown up a great deal.

 

Except this: http://www.ebay.com.au/itm/251547958309 which doesn’t count :D

 

There are very few genuine Class A amplifiers. Most manufacturers lie about the ratings, in order to gather more sales. The Musical Fidelity A1, for instance, was rated 20 Watts Class A. It's actual Class A power was somewhere less than 2 Watts Class A. Not that there is anything wrong with that. 2 Watts Class A is a very substantial amount of Class A power for any amplifier. More than sufficient for most situations. The other issue is that of sound quality. There is no evidence to suggest that a Class A amplifier sounds better than a PROPERLY designed Class A/B one. 

 

If you really must look to a Class A amplifier, then the Silicon Chip 20 Watt Class A amplifier is one of the best. It is a genuine 20 Watts Class A and sounds very fine indeed. Altronics stock the DIY kit. 

 

http://www.altronics.com.au/p/k5125-20w-class-a-amplifier-full-kit/

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The Musical Fidelity A1, for instance, was rated 20 Watts Class A. It's actual Class A power was somewhere less than 2 Watts Class A

Yup all crap - please send to me and I'll dispose of them properly. :)

 

The circuit is most unconventional and the designer Tim de Paravicini states it provides 20W class A - looking at the schematic I can't argue with his reasoning.  Mark Hennessey's page http://www.markhennessy.co.uk/mf_a1/ is probably the best out there if you want to do some homework.

 

Now all the other MF "A" amps do not produce anything like this amount of class A and some are completely conventional AB amplifiers.

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The diy amps you have there from opc might become commercially available yet ;)

(No idea when but its certainly on the cards)

 

There is no evidence to suggest that a Class A amplifier sounds better than a PROPERLY designed Class A/B one. 

 

If you really must look to a Class A amplifier, then the Silicon Chip 20 Watt Class A amplifier is one of the best. It is a genuine 20 Watts Class A and sounds very fine indeed. Altronics stock the DIY kit. 

 

http://www.altronics.com.au/p/k5125-20w-class-a-amplifier-full-kit/

 

Yes, I'm aware of the Silicon Chip 20 Watt Class A, it looks great, but it's DIY. Just curious as to what similar non DIY products are there. My next likely amp I'll build will be Class AB -

 

I've also got OPC LPUHP pcbs waiting for when I get around to it as the next possible amplification upgrade - they are 15W class AB. Would be great if he made them available as assembled units.

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What about Nelson Pass ,First Watt series of amps .  I don't really know if theyre class A .

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What about Nelson Pass ,First Watt series of amps .  I don't really know if theyre class A .

all of them are class A, ...or they were until they left and go to B :D

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Yup all crap - please send to me and I'll dispose of them properly. :)

I never suggested that the A1 was crap. Far from it. It is one of the nicest, small SS amps ever made. It is not even remotely close to 20 Watts Class A, however.

 

The circuit is most unconventional and the designer Tim de Paravicini states it provides 20W class A - looking at the schematic I can't argue with his reasoning.  Mark Hennessey's page http://www.markhennessy.co.uk/mf_a1/ is probably the best out there if you want to do some homework.

I've measured several A1 amps. Class A power is around 1.75 Watts. The method MF chose to arrange the heat sinks prevents any more Class A power to be available.

 

Now all the other MF "A" amps do not produce anything like this amount of class A and some are completely conventional AB amplifiers.

Sure. Some time ago, I worked on an MF A370. It was claimed to be 185 Watts Class A. It was not. It was around 12 Watts Class A. Certainly, a healthy amount of Class A, but not what it was claimed to be. Just like the A1.

Edited by Zaphod Beeblebrox

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What about Nelson Pass ,First Watt series of amps .  I don't really know if theyre class A .

All single ended MUST be Class A. The First Watt is a single ended design.

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All single ended MUST be Class A. The First Watt is a single ended design.

I think the F5 is a push-pull, some of the other First Watt amps are single ended... not that I'm an expert :-)

SS

Edited by Sub Sonic

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I think the F5 is a push-pull, some of the others are single ended... not that I'm an expert :-)

SS

what do you think of the F5? i think i remembered you built one.

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The method MF chose to arrange the heat sinks prevents any more Class A power to be available.

How so?  

Edited by thoglette

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How so?

The heat sink can only operate as a radiator, rather than a convection cooled one. Convection cooling is vastly more efficient.

In fact, I plan to present an experiment I will be performing with the most popular cooling systems in a week or two. I will include a radiative heat sink, despite the fact that no designer uses such a system, due to it's low efficiency.

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what do you think of the F5? i think i remembered you built one.

Hi Henry,

It's still in the works, one of the many projects which make this hobby so much fun! :-)

Regards,

SS

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The heat sink can only operate as a radiator, rather than a convection cooled one. Convection cooling is vastly more efficient.In fact, I plan to present an experiment I will be performing with the most popular cooling systems in a week or two. I will include a radiative heat sink, despite the fact that no designer uses such a system, due to it's low efficiency.

Yes, the A1 always struck me as having a most inefficient heatsink design for "Class A".

SS

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I'm no expert in the area of design but I can see that this amp at least has decent sized Torroidals.

 

http://www.cattylink.com/page380.html

 

I've got the A/B version, the S200 and it's a decent piece of kit.

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The heat sink can only operate as a radiator, rather than a convection cooled one. Convection cooling is vastly more efficient.

And?   Why does this stop the amplifier operating as designed ?    

 

Others report a standing current of c. 700mA  per side and a static consumption of c. 80W.  Which is entirely consistent with ten or twenty watts of class A output. 

 

What was the standing current you measured? How did you determine that the amplifier was either shutting down or otherwise leaving class A at below 2 watts?

 

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A friend of mine has built a number of F5s. The bottom end is extremely extended. But apart from that I think they are ordinary.

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