Boosting a Warwick Sonic II giving trouble

[aceofspades_71]

Hi to all and glad to join you!

I don't know if this has been discussed before, but as far as I've searched, I haven't found any entry about boosting power in a transistor amp. I know this is a tube-focused discussion place, but I'm in a sort of trouble, and I don't know anywhere else to look for help.

I've got a Warwick Sonic II amp (200W 4ohms) attached to 2 cabinets (150 W 8ohms 2x12" - 200W 8ohms 1x15"). It has been working relatively well until, I don't know how, it blew the two fuses in the amp. Changing them meant a funny consecutive fuse blowing (I think I blew 9 or 10 of them) until it stopped working. I guess that the problem is in the power source (a 250W toroidal one).

But I'm afraid that 200W is not enough to fight against the Marshall 4x10" that the guitar player uses, so I was thinking of trying to boost the power, taking advantage of the fact that the guts of the poor thing are spread all over my room. I don't know if it would be difficult/impossible/hilarious to increase the amp to 350W. My questions are:

1.- Would I achieve this change placing a 350W toroid (or not toroid, whatever shape it may have) power source?
2.- If affirmative, what else should I change?
3.- Could anyone indicate me somewhere in which a similar issue is explained for dummies?

I'm more into guitar building, so amp tech skills are a pending due for me. I'll thank very much any comments about this.

All the best and greetings from Barcelona. Thanks a lot!

[Enzo]

200 watts into 4 ohms, and two 8 ohm cabs means 100 watts per cab.

When a amp blows a fuse, and then blows another fuse, STOP PUTTING FUSES IN IT. Clearly it has a problem. Most likely problem is shorted power transistors. Or maybe shorted rectifiers. Unlikely but possible is shorted filter caps. The power transformer COULD be bad, but that would be unusual.

Connect the power toroid to the mains while leaving the secondary wires disconnected. If it still blows fuses, then it is bad. If the fuse does NOT blow with the secondaries inwired, then the toroid is probably good.

There is no simple way to increase power in a solid state amp. Power is a matter of how much voltage you can throw at the speaker, and having enough current to hold up under the load. To increase power, the power supply coltage would have to increase, and that would require your new toroid, yes. But you then also need to worry whether the power transistors are up to the higher voltages and higher current demands. Also we worry that the cooling capability of the heat sinks can handle the increases even if the transistors are able.

If you double the 200 watts to 400 watts, the increase in loudness would only be 3db. That is not a lot. If you changed your speakers to ones that had 3db higher efficiency ratings, it would have the same effect.

Remember also that the two speaker cabs will share equally, so 350 watts power would result in 175 watts per cab. That exceeds the rating of one of your cabs already.

COnsider running a line to the PA system for added sound.

You might look into a more powerful amp, or consider a second power amp and speaker cab, and run a line out from the Warwick to that.

[Steve Conner]

If you didn't know enough about electronics to fix the amp yourself without asking for help, I say you don't know enough to modify it for increased power, so don't bother.

I'm sorry if that sounds mean, but the musical instrument market is cost conscious, so solid-state amps are made of cheap and nasty components driven as hard as possible, to give the customer the most nameplate watts for his buck. To uprate the power, like Enzo suggested, you'd need to replace all the most expensive components, by which time you could just have bought a 1kW Crest power amp on eBay, made a nice rackmount tube preamp to go with it, and blasted your guitarist (and your speakers) halfway to Portugal.

PS. Remember when working with transistor amps "The fuse is always the last thing to blow" Those two fuses are just to stop the thing going on fire once the output transistors have blown.

[aceofspades_71]

I really thank very much both your comments, and don't worry, cause that didn't sound mean, but realistic. Anyway, I think I'm getting on the right track, and fortunately I can get a grab on some good parts from a local electronic parts dealer. Well, so if I there aren't any further news from me in a short-time future, it'll mean I've been enveloped in flames and died on my purpose! Thanks a lot again