Back to the Future - repurposing old amps for Class D

[stocktrader200]

is that an old luxman? What a beauty.
Twin power supplies lots of space. I am installing a 3 channel class D of my own design into a pioneer sx3700. The power rails in this reciever are +- 42volts
You would have to measure the voltage across the large caps (carefully) to determine what modules to buy. There looks to be enough space for multiple channels.
The easiest approach would be to remove both the heat sinks from the old amp and associated connections. Then install the class D modules where the heatsinks were.
Left channel
You will have to find the main Amp Input and output

Connect module to Left power bank (at power transistors or filter caps)
left signal input to signal input of old amp
output of module to left amp output main on board of old amp
(trace output transistors back to board)
(gate,base) = amplifier drivers
(Drain,collector) = Power supply (follower output)
(Source,Emitter) = Speaker output
All components of old amp can be rremoved
Repeat for right channel

[5th element]

Originally Posted by von.ah

They both have meters.

So they do!

I of course was referring to the amplifier with the front panel that's dominated by the VU meters, but I think that much was perhaps obvious.

This thread has given me inspiration for perhaps sniffing out a decrepit amplifier on ebay and salvaging it's case for my two digital amps that I've just built. I'd certainly use that luxman if that's what it is, or something like this



if I could get my hands on one.

[mfong]

I just did something like that this weekend. I had an amp from Audio Amateur days, the Lang 20 Watt Class A, that I had put in a case. It died a few years ago and was sitting in my garage. I pulled out the boards and power supply (transformer had died) and slipped in one of Arjen Helder's Tripath 2020 boards. Really the only things I saved were the case itself, the power switch, the rca inputs, and the speaker connectors.

I was very pleasantly surprised by the sound with my big speakers (8" 3 way/ accuton tweeter and mid and cabasse woofer) ported and not especially efficient high 80's maybe. I've actually had low power class A amps and a 300B in big cases before. The class D stuff I've had has been in little boxes. It may have been psychological, but with the little 2020 inside the big box, the sheer amount of bass from the amp was amazing (it was also clean and with some snap unlike the Lang, the Pass 40's, and the 300B I'd had in the past) It's also very open sounding.

My take was that Arjen's board is noticeably higher quality than his modified Topping tp 20. Having it inside a bigger box also made it easier to believe that that much sound was coming through the thing. It may also be that the various components happened to match well.

Eventually, I'm going to put a second board in and bi-wire, but I'm not sure I need to do that to be happy with the sound. So the board was about $25, the case was sitting in my garage, and the switch mode 12 volt power supply was 12.50 with .99 for the input connector. It's hard to compare across the years but I'm pretty sure this is competitive with amps I spent several hundred dollars on twenty years ago.

[Pano]

Originally Posted by von.ah

By collaborating I mean you do it.

LOL. Well maybe. I have quite a few class-D amps that could work.
All the project needs is a case - and the time to do it. :-/

[von.ah]

http://www.parttimeprojects.com/audio/diy/index.php

This is a heck of a site demonstrating the re-use of old enclosures. Cool stuff.
I know this DIYer is a member here, but forget who he is...