The Amp Garage

Thanks for the detailed explanation Scumback! It is clear now. By personal experience, the data shown is more a copy-paste rather than something else (same power at the same THD for two very different schematics is not so easy to be obtained). Also, whilst I can agree with the low THD wattage, the ...

roberto, I'm sorry, but that tech and I are no longer friends, so I'm not going to shoot you his email. The simple answer is this... Clean, 8 ohm, 1khz signal to the high input of Ch 1, the amp was 55w rms, around 4 on the volume knob of the 1987 clone. Distorted, 8 ohm, 1 khz signal to the high inp...

Again, don't assume or guess. Amp tech did the math on the amp when it was built. After I got it I took the Volt measurement of the cab's input jack. I did no calculations, the amp tech did. just reported what the voltages read at the cab when turned up to where the amp tech said it made power at ce...

Well, pdf64, I've had the amp measured both ways. Once when it was built, sine wave, 1khz signal, 8 ohm input and measured at the output by my amp tech. The second way was by me the DMM at the cab input jack. The wattages I was given were done by the amp tech in test mode, the voltages I gave were w...

Yeha I hear magnets are a pita to ship. I accidentally ordered a 15ohm celestion alnico gold, when I wanted 8, and when I told amazon, they were like. "we'll just refund you, returning it is too complex, you can keep it, and/or buy the right one" :D I was like... yeah I'll just keep it. ~Phil I've ...

Don't get me started...LOL

Speaking only for myself, I usually sell extra stuff out of the shop that isn't needed. Usually it's not something I make, so there's really not much to promote or consider as something I am a vendor for. I'm trying to clean out the shop of all the stuff I've accumulated over the last 20 years so I ...

roberto: Regarding the voltage reading I do...I just use a standard multi-meter and set it to Volts and measure the input jack on the 4x12 cab for my reading.

Speaker power handling is based on the melting point of the voice coil former material. The signal power sent has a voltage to it, roughly 36w on a 50w 1987 Marshall cranked up to 8-9 on a NMV amp circuit. in my 50w, that's around 95w output, resulting in 36 volts at the cab speaker jack. I've measu...

nworbetan: Apparently there are players boosting the front end of their 4 stage amps with the usual pedals (bosst, phase/flanger, fuzz, etc) and then if the amp has an fx loop in front of the power amp (but after the preamp / PI) they'll put a boost pedal for 10-20db there to create a huge increase ...

wpaulvogel: yeah the two amp builders I talked to said basically the same thing as you about the square wave from the preamp increasing the signal to the PI and beyond, well past clipping, etc. One amp maker measured 122w with dual EL34's, the other measured 118w. I always figured no one would go pa...

From an electrical standpoint, I'd guess one would want a speaker rated for at least twice the power rating given by the amp because this power spec almost certainly was done with sin waves and not square waves. So the amp could deliver double that. +1! I'd hedge that a bit more and say two to thre...

Hi Jim Hope you're well. Been a long time mate! Try this resource: https://www.ampbooks.com/mobile/classic-circuits/soldano-slo/ It's great write up for understanding the preamp section of the legendary SLO. Cheers Kurt Hey Kurt! We can always stuff your gut with lasagna next time you're in So Cal!...

There's a melting point from heat applied to the voice coil that determines the power rating, also coupled with coil diameter, former material, whether it's a heat treated nomex paper or plain paper coil, etc. That all goes out the window with a square wave, though.

Hey Roe! Apparently with the SLO design the 4th preamp stage and tube add on in a way that increases RMS, too. It may not be as intense as a fuzz box, but it approaches that level of square wave signal. The extra strength/heat/etc in the square wave signal will cause a voice coil to hang open long e...