Does anyone know what amp this is and who makes it?

[MikeHunt79]

I got these amps for next to nothing, and I'm after a schematic, but I don't know who makes it or what model it is.

I've already hacksawed the PCB in half on one of them and now it doesn't work, so I'd like to find some more info before I get again.

[MikeHunt79]

in sides

[ppia600]

Kiind of looks like pyramid

[MikeHunt79]

Originally posted by ppia600
Kiind of looks like pyramid

I've never seen pyramid stuff in the UK, but I guess it could be around, or even sold under another name but from the same factory.

Anyway... It's now been fixed so I no longer need datasheets or anything, so delete this if ya like mods.

[spooney]

how do they sound?What are they using for output transistors?

[Eva]

Looks like 4 x 75W "generic Chinese". This stuff was available through several brands, and Pyramid was one of them. Some stuff from Magnat and Jensen probably came from the same factory. Are the outputs B778 and D998?

[MikeHunt79]

Originally posted by Eva
Looks like 4 x 75W "generic Chinese". This stuff was available through several brands, and Pyramid was one of them. Some stuff from Magnat and Jensen probably came from the same factory. Are the outputs B778 and D998?

Yep, B778's and D998's, only one of them works, on 3 of the 4 channels, so I butchered them, and managed to use the power supply from one. I still have the other for spares....

I them put in a 4 x 100W class D module, and it works really well... I just need to figure out how to squeeze an active crosser or two onthere somehow...

[Eva]

In most circuits you can replace these hard to find output transistors by the widely available (at least in Europe) TIP35C and TIP36C, just in case you want to repair one of the amps...

In the end you may find more exciting to design and etch your own PCB, get your own parts and build your own SMPS

The following thread may give you some motivation, if you haven't already seen it
Cool and small 2x150W class D full-range car amplifier

[MikeHunt79]

Originally posted by Eva
[B]In most circuits you can replace these hard to find output transistors by the widely available (at least in Europe) TIP35C and TIP36C, just in case you want to repair one of the amps...

Thanks, I'll keep that in mind... even tho I now have quite a few spares after I hacksawed the amp part of off one of the amps.

FWIW, I tested it all out today, and it sounds nice and clean, certainly an improvement on the original.

For now I'm happy with my quick and dirty solution, as right now I'm using the inbuilt amp on my HU.

If I was to do it again, I probably would do my own circuit, or change the toroid at least... as this amp has 24v rails, and I only actually used the +ve rail for my class D module, so I have the -ve rail sitting there with no load. I may use the -ve rail for powering op amp at a later time tho... I only read up on push-pull supplies a few days ago, I'm still getting used to it all, but I'm glad to say I haven't released any magic smoke (yet).

I read your class D car amp thread btw, I love how compact that thing is... I think you may be the first person with class D on a motorbike!

Also, I've decided to go with a separate pre-amp, I can't really squeeze any more in this amp case apart from a small voltage summer circuit to make my bass mono...