amp-thing

imalone

I've been putting together a solid state amp for some time (holidays only project), and have got it vaguely working.
http://youtu.be/uaZVDWtrwrM
Still some tweaking to do, it's not developing the power it should as it's not regulated and the power supply (DC PSU) puts out a higher voltage than it's supposed to (which is messing up biasing in various places). Also planning to get hold of an oscilloscope to check whether the preamp gain needs increased. But one thing I could do with advice on is what speakers to look at, the low volume is as much down to the spectacular 86dB speaker as the biasing problem. Something like the celestion rocket 10 is pretty cheap new (lets face it, I'm not putting a high end speaker in, certainly not yet anyway), or I could try and get hold of something second hand.

ICBM

It really is worth getting the best speaker you can. It makes far more difference than any other component.

Something like a Celestion G10 Vintage is not that expensive really, and the difference it will make to the volume and tone will be nothing short of stunning compared to what you have - it's 97dB, which is like increasing the power of the amp ten-fold relative to the 86dB one. A very midrangy, peaky speaker like that with a rolled-off top-end actually makes a solid-state amp sound more 'valve-like'... assuming that's what you want.

It might not be a good idea to regulate the power supply too well either - that could make it sound rather flat. One of the desirable characteristics of many valve amps is fairly poor regulation.

imalone

Thanks, I'll have a look. Yes, the current speaker is fairly terrible and was chosen to be sacrificial, since I couldn't be entirely sure it wasn't going to get toasted.

imalone

Well this arrived last week.

That small blue box is the old speaker. I'm going to have to adjust things again since what I thought was the amp clipping was actually the 4" speaker unable to cope. A G10 vintage has no such problem:

(Hiss is my phone camera, the amp itself is near noiseless, certainly much so than the Vaporizer I tried earlier this week.)

There's still an upsetting oscillation that sets in when using a wah. An oscilloscope is on its way which should help track that down.
Next step: build cab. Planning to set things up so I can also use it as a cab for my pathfinder, since the speaker is probably too good to tie up on this project alone.