Hello everyone, it has been a while since I have made any posts on the forum, so here is a project that I have been working on since christmas, yea it took a while to get this beast up and running due to the fact that the shape it was in was so bad that I had to strip the chassis down and soak it with cleaning solutions as it had rat and mouse droppings all over it. I will post some pictures.... I think anyone would agree that it really looked like a worthless piece of junk that likely had one of the two transformers fried on it.
The amplifier is a classic old EL6431 Philips amp, it uses 4XEL34 with an insane supply rail of 825V!
It has a funny output transformer, 70 volts all the way down to 10 volt switchable impedance, this being said, 10V = the 8 ohm tap.
In the end this thing turned into a really cool looking purple chassis instrument mono block amplifier, AKA "The purple Amp" or "The Crushinator" due to the very dense mass of the thing.
I will post some pictures, so here are some added features....
- Selenium be gone, better ventilation, much cooler running and better power efficiency due to the use of Silicon rectifiers.
- High voltage relay added to give the output tubes more time to warm up.
- Bias supply is mosfet regulated for added stability and reliability, it is also voltage adjustable with the use of a pot.
- power supply uses two 330MFD 450V high temp capacitors in series to gain better noise rejection and regulation in the 825 volt supply .
- One mic input converted to high impedance guitar input with 1/4" jack.
As for sound wise, this thing sounds great, it has a very "fat" bottom end, not "soft" like when a tube rectifier is used. perfect for an electric bass, which sounds way better than the amp that came with my bass. The best part is that I can hook up any audio source and gig along with what I play as each input has it's own volume control.
Music sounds smooth in the highs, a very unique but natural sound, and there is that warm sound of tube distortion, and the bottom end reveals each bass line that is played in a song very well, like I said before, the amplifier sounds quite "fat" in terms of bass.
I'm not sure how common this amplifier is, but If anyone was to get a hold of one let me know as I will have schematics and procedures at which to take when it comes time to fire the amplifier up as it is not safe just to plug it in and hope for the best, especially if with the state I found this one in.