another one to build an AV800 / AV1000

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Hi Forum

I'm new here and first of all I'd like to say hello and introduce myself.

From the subject you see I intend to build an AV800 or AV1000 amplifier designed by Anthony Holton. I started this project some time ago, bought a lot of parts and then stopped the project for many reasons, among them the lack of need for an amplifier at all. One of the other reasons is that I work as an electronics engineer and pcb designer so after work I don't like to spend my spare time with electronics. When cleaning up I found the box filled with parts again and made up my mind what to do with them.
Since I already invested some money in parts I decided to finish what I have started. Selling parts most likely won't bring much money so I better build an amp. I intend to sell parts I don't need for the amp after it's finished.

If you need parts required for the AV800 and can't find it you may write to me. I might have a lot of them I don't need - or not.

Starting in spring is a bad idea because I like to spend my summer in another way than to sit in front of my laptop designing or assembling pcbs. But in the meantime my skill designing things has increased so finish my designs much faster than a few years ago.

Many of those who attempted to build an AV800, AV1000 or an insane project based on them failed for various reasons or maybe just stopped their projects like me. I already built an amp long time ago that is so butt ugly I can't show you. From this project I learned some things and hope to succeed with this monster amp project. I hope to find help from the community for the case I experience problems with my amp and I also will try to help others.

This thread is intended to become a diary of building my amp. I will post progress, ask four your opinion, ask for help and just blog a little. You are welcome to post but please stay on topic a bit. I wouldn't like to end up discussing about tube amps in the end. ;)

Attached a picture of some parts I already bought:
two huge toroids, 1kVA each
100 IRFP240
100 IRFP9240
25 Caps, each 10.000uF 100V
and some other semiconductors

You see I'm serious. :bigeyes:
 

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Hi Forum

I'm new here and first of all I'd like to say hello and introduce myself.

From the subject you see I intend to build an AV800 or AV1000 amplifier designed by Anthony Holton. I started this project some time ago, bought a lot of parts and then stopped the project for many reasons, among them the lack of need for an amplifier at all. One of the other reasons is that I work as an electronics engineer and pcb designer so after work I don't like to spend my spare time with electronics. When cleaning up I found the box filled with parts again and made up my mind what to do with them.
Since I already invested some money in parts I decided to finish what I have started. Selling parts most likely won't bring much money so I better build an amp. I intend to sell parts I don't need for the amp after it's finished.

If you need parts required for the AV800 and can't find it you may write to me. I might have a lot of them I don't need - or not.

Starting in spring is a bad idea because I like to spend my summer in another way than to sit in front of my laptop designing or assembling pcbs. But in the meantime my skill designing things has increased so finish my designs much faster than a few years ago.

Many of those who attempted to build an AV800, AV1000 or an insane project based on them failed for various reasons or maybe just stopped their projects like me. I already built an amp long time ago that is so butt ugly I can't show you. From this project I learned some things and hope to succeed with this monster amp project. I hope to find help from the community for the case I experience problems with my amp and I also will try to help others.

This thread is intended to become a diary of building my amp. I will post progress, ask four your opinion, ask for help and just blog a little. You are welcome to post but please stay on topic a bit. I wouldn't like to end up discussing about tube amps in the end. ;)

Attached a picture of some parts I already bought:
two huge toroids, 1kVA each
100 IRFP240
100 IRFP9240
25 Caps, each 10.000uF 100V
and some other semiconductors

You see I'm serious. :bigeyes:

Hi Lee,
How many toroid u have and how much the rating, if u r willing to sell how much the price?

smblite
 
I spent half the weekend simulating the amp using LTSpice. From this I learned a few things:
The amp topology works. ;)
It's performance seems to be okay.
Spice can be a handy tool used properly.
When strange things happen the reason sometimes is very uncomplex. :headbash: I wondered for hours why simulation showed 11% THD and did not notice I ran the amp at 50kHz and about 700W peak. :ashamed:

I like the topology of this amp, the differential stages, FETs only in the output stage and it's straightforward. I don't know much about audio circuits but to me it makes sense.

After simulation I have a better understanding of how it works what is important to design a good pcb. Most parts are already defined and I can start pcb design soon...
 
you have picture for av 1000 pcb?

Is this an offer or do you need a picture? ;)

For the case you are looking for pictures go to archive.org where you can find previous versions of Anthony's website and lots of pictures from the bare board, assembled boards, Anthony himself and many other things. :)
I went there just today because I was looking for a schematic...

By the way: Navigation of the website does not work. You need to read the source and navigate manually.
 
Hi Andrew

Thank you for the photos of the schematic.
Unfortunately the forum does not allow high resolution pictures attached to a post. Would you mind sending them by email to me? I sent you a pm with my address.

What I see now makes me even more curious. There are some BJTs for bias and in the buffer stage but you wrote to use hexfets for driving. Some component values have changed but I can't read all of them.

I will post a redrawn schematic here so others interested in the amp can see.

Thanks a lot.
Lee
 
Hi all

Just a little update.

I'm stuck with the schematic a bit and started pcb design already to have some progress. Cleaning up my design directories I found my first design again. I'll show it to you just for entertainment. ;)

I intended to mount the output devices on both sides of the pcb to L-shaped heat conductors that were to mount on the main heatsink. The idea behind was to have a compact module that allows easy testing and maintenance. This was a misconception because removing the module from the heatsink would require to detach the heatsing from the case anyway. I planed to have tall parts on both sides of the pcb what makes the arrangement waste a lot of space. Another bad thing about it is that the thermal resistance is far too high to have efficient cooling. The only way to go is to mount the output devices to the heatsink directly.
 

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Attached you find a preview of what the new pcb design might look like. I just put most of the components inside the board and didn't start routing yet.
The design will be more compact and has better thermal performance. One thing that I don't like about it is that one row of output devices is located where the cold air enters the heat sink ant the other one is located where the hot air leaves the heat sink.
 

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