Once I had a A-40...

[Gladiator33]

For 20 years ago I had a A-40. I can not forget that sound!

What spesific amp of these is the nearest i sound: Threshold, Pass labs and Nakamichi.

Please give som advice! The amp will have Klipsch RF-7 to handle.

Best regards

 

[Nelson Pass]

Maybe you should just build an A40. The outputs are no longer
available, but you can get some Motorola Darlingtons. The rest
of the parts were generic. Replace the Tantalum cap with the Elna
silk.

 

[mjf]

hello.
if you like it perhaps you can build it - schematic,layout and so on are still available..............
i used tip 141/ tip 146 for output transistors (offset about 22mv) and i reduced the biascurrent a little bit ........
greetings.............

 

[Gladiator33]

Thanx for answer! I have the schematics for A-40, but not the time to build it! I loved the sweet holographic sound

 

[gpsmithii]

These have worked well for me as output devices over the last few years. You will have to adjust the bias, but they are still available at a reasonable price.

http://www.onsemi.com/pub_link/Collateral/MJ11012-D.PDF

MJ11015 & 16

It's a great amp!

 

[llwhtt]

I am in the process of building an A40 now. I tracked down all of the original parts including the output xsistors and the Signal 88-8 pwr xfmr. They will still make one for you on special order.
It's going into an old Sumo Andromeda II chassis, the heatsinks are just about the perfect size according to the equations in an old Audio Amateur article, the same issue the A40 came out in I think. Standard Radio in NY has the Lambda xsistors, .68 Ohm 1 Watt 1% WW Dales, the MPLSxxs too. Going to try and use a 1N530x in place of the FET. Can't wait to hear it, this project is way overdue.

Craig

 

[Gladiator33]

I have got my hands on an A40 from mid '80. The amp is constructed as a tank! Everything is original from that time. And the price? Half of component cost!

I will bring You pics and sound descriptions.

Lucky me.....

 

[Gladiator33]

THE AMP is here! I love this sound! My tubeamp is packed away...

In this amp there is fuses not only in the negative rail, but also in the positive rail. Is that any problems?

The construction of this DIY amp is outstanding, magnifik! Better than many fabric-amps.

 

[llwhtt]

I too have noticed that Mr. Pass uses a fuse in the negative rail only on many of the amps I've seen, why is that Mr. Pass?

Craig

 

[HKC]

I built my A40 in 2007 and still using it. A40 is a very good sounding class A power amp. It replaced my classic Pioneer M22 in my stereo system

 

[Nelson Pass]

I too have noticed that Mr. Pass uses a fuse in the negative rail only on many of the amps I've seen, why is that Mr. Pass?

Those circuits are constructed such that if you interrupt just
the positive rail, they will go into DC offset at the output. If
you interrupt just the negative, they will sit there quietly,
like good dogs.

 

[Blues]

Those circuits are constructed such that if you interrupt just
the positive rail, they will go into DC offset at the output. If
you interrupt just the negative, they will sit there quietly,
like good dogs.

Mr. Pass,

I found in simulation that turning off the +supply of an Aleph also makes it sit there (quietly like a good dog) with very very low DC offset. Is this true in a real circuit? If this is so, then this is a good way to keep an Aleph on standby...

 

[Gladiator33]

Those circuits are constructed such that if you interrupt just
the positive rail, they will go into DC offset at the output. If
you interrupt just the negative, they will sit there quietly,
like good dogs.

Thanks for this information. It meens that I must shunt the fuses in the positive rail or put in a 20A fuse...?

 

[Nelson Pass]

I found in simulation that turning off the +supply of an Aleph also makes it sit there (quietly like a good dog) with very very low DC offset. Is this true in a real circuit?

As I recall, yes.

 

[Blues]

Thank you!

 

[Gladiator33]

My A40

Bump.

Here is my A40. The amp has now got a competitor; Stasis 3!

 

[Gladiator33]

BTW; I read this in another tread: "I couldn't tell from the pictures but are your heat-sinks grounded to their chassis and are the amp chassis grounded to the power supply chassis? Nelson made it a point in the original article that the heat-sinks must be grounded."

My A40 has no grounded heatsinks. What is the benefit for doing that?

 

[Eric]

My A40 is built with a wooden chassis and my sinks are not grounded either. 12 years later and not a problem at all...

 

[AndrewT]

My teacher had an A40. It looked quite different and I don't think it had a wooden chassis. That was the Morgan.

 

[Gladiator33]

^ But did it have heat-sink...? ;-)