There are car audio and PA type speakers that, on paper, have similar characteristics to guitar speakers in terms of frequency response, resonance, impedance curves and whatnot. Specifically, so-called "midbass" or "midwoofer" speakers, Some boast really huge power handling, like even a 1000W for one speaker.  I don't recall seeing efficiency quotes of more than 98 dB on these things.

Here is one claiming 3000W RMS: https://ds18.com/products/pro-3kp12-8

The resonant frequency and cited range seem good for bass. Sensitivity is only 95 dB though.

This 1250W one claims a respectable 99dB, a more extended frequency response from 45 Hz to 5 kHz, and a 68 Hz resonance: https://ds18.com/products/12pro2500mb-8

A 4x12 cab loaded with these would be completely insane.

I'd love to experience what these types of speakers are like for guitar, for sure.

Quote from: Wattsup on May 18, 2026, 09:36:31 PMAlso, what is the purpose of this on your board? Neither of my amps feature this on theirs.

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Reverb driver transformer.
In the pre-amp schematic on page #1 post #1
It is the component labeled T1.

Different versions of these amps out there, and probably a few different, but very similar circuit versions.

They likely figured out that it was possible to drive the reverb "tank" directly,
rather than use the transformer.

I have other Teisco amps that don't have the reverb driver transformer,
but very similar reverb tank and circuit design to this one.

Quote from: Wattsup on May 18, 2026, 09:29:24 PMAh, these guys? I shall check those on both of the amps that I have and see what readings I get.
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Regarding the capacitor used for C1 on the power board, Panasonic 1000uF 35V (I think of FR series).

Each of the amps have a standard 3 wire UK power cord.

Yes, those guys. 

Also, what is the purpose of this on your board? Neither of my amps feature this on theirs.

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Ah, these guys? I shall check those on both of the amps that I have and see what readings I get.
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Regarding the capacitor used for C1 on the power board, Panasonic 1000uF 35V (I think of FR series).

Each of the amps have a standard 3 wire UK power cord.

Quote from: Wattsup on May 17, 2026, 07:49:52 PMYes, I have replaced all electrolytic capacitors including those on the power board, and carefully observed correct polarity when replacing.

Which diodes on the power board are likely to be the cause for the hum?

D1 and D2 in the power amp schematic in post #1.

Edit:
Also, have you added a 3 wire grounded power cord?
This is a must for safety.
Helps for noise/hum as well.

What value capacitor did you use for C1 on the power amp board?

Yes, I have replaced all electrolytic capacitors including those on the power board, and carefully observed correct polarity when replacing.

Which diodes on the power board are likely to be the cause for the hum?

Quote from: Wattsup on May 17, 2026, 07:52:23 AMI have acquired a couple of these exact same amps which I am in the process or restoring. At first the reverb and tremolo were non functional, output signal was low, and there was much noise and crackle on the audio output. However, after replacing all of the electrolytic capacitors, these problems and issues appear to be fixed. However, there is still a fairly loud hum heard through the speaker on both of the amps, even when the volume of the amp is turned all the way down. Any suggestions or insights for how to possibly reduce or eliminate this hum?   

You say you replaced all caps.
Does this include the power supply cap?
Did you observe correct polarity when you replaced them?

These amps are Positive Ground!
Cap positive goes to Ground.

Also check the Diodes at the power supply.

I have acquired a couple of these exact same amps which I am in the process or restoring. At first the reverb and tremolo were non functional, output signal was low, and there was much noise and crackle on the audio output. However, after replacing all of the electrolytic capacitors, these problems and issues appear to be fixed. However, there is still a fairly loud hum heard through the speaker on both of the amps, even when the volume of the amp is turned all the way down. Any suggestions or insights for how to possibly reduce or eliminate this hum?   

A few years ago I had a RocPro 700 that was having this exact issue. At first I thought it was the speaker. Went through everything but couldn't figure out why it was misbehaving. After installing the 47pf or something close it finally sounded like an amp again. So yes this seems like a bandaid repair but it certainly solved the issue.