Class A project

Hi all,

I am planning on starting on a new amp and I am just trawling for inspiration. I have build a few Class T's and work professionally with embedded uP but I feel like its time to go back to basics. I am planning on building two mono-blocks in pure Class-A. Cost and power are not major concerns but I don't want to get too crazy with either. I am quite taken by the simplicity of the pass labs circuits but I don't know which one to pursue.

The Aleph 2 looks very appropriate but browsing other threads has left me curious about the performance of projects like the reverse engineered x100 (I understand Mr Pass's new designs are significantly superior to the Aleph series so there must be room for improvement!).

Does anyone have any opinions on what the best sounding diy designs are?

On another note, where do people get hold of matched output devices in the UK without buying hundreds of them?

Rahul Powar


2001-06-01 4:53 pm
sabermann said:
(I understand Mr Pass's new designs are significantly superior to the Aleph series so there must be room for improvement!).
There's always room for improvement. That's why we keep building them.
One thing to be aware of is that some of the circuits here were not designed to production standard, and component tolerances and layout may cause you grief (instability, etc.). I think the backengineered X100 may be an example. One guy might be able to get it running right in his basement, but the next guy runs into all kinds of problems. So unless you have a good handle on analog circuitry, best to steer clear of the homebrew stuff until you've sharpened up on some more forgiving stuff.
dshortt9 said:
So much depends on you speakers and preamp. What are you using?

If you suspect that your system is not up to the task because of the preamp, throw it out, you'll do yourself a big favour. Try to use a passive one and find out what you've been missing. Speakers are important, but I think that everything depends on your sources. After all the music starts in there.;)
I have a fan less embedded PC as the source with a M-Audio Dio 24/96 as the sound card. I am using the onboard DAC's which is not ideal but will have to do for now (a DIY DAC is my next project). I will probably upgrade that to another of the M-Audios with more digital outputs so i can play with PC based digital cross overs. The audio itself is extracted from CD by a mastering level duplication setup that I developed for a company and stored using loss less compression. So, except for the quality of the onboard DAC's, the source is decent. The speakers are a fairly standard mdf reflex enclosure based on the Scan-Speak revelator series though I am investigating a sealed design using a aluminum skinned polymer material.. though that is a different discussion.

I have a reasonable amount of experience with stability issues and good design practices, though mainly in the digital domain. As for this project, I am quite willing to jump into the deep end! My main question is what amplifier design people generally belive provided the best all-round musical experience (I know that is a totally subjective and wide open question, just wanted some thoughts). Thanks for all your responses.

on the music part. I listen to allmost everything, classical, jazz, pop, rock, from Bach, Travis, Rammstein, Slayer etc.

I own a pair of B&W Nautilus 802 loudspeakers and have used (borrowed), Mark Levinson 383, 380S+336, Gamut D200, Pass X150, Classe Cap-151 etc.

I now have build an Aleph 4 and I am using a real Pass Aleph P which I bought second handed as preamp.

I must say, I am very very pleased with the Aleph 4, even when I look back at the mighty levinsons. The music seems to flow as water from the speakers, no grain at all, nice tight bass, beautifull spacious sound around the instruments.

Do not bother in thinking about doing better. I know for a fact that you will be pleased with your Aleph 4!