Bill Fitzmaurice

If you want to get rid of that dip it's easy enough, reduce Pe to 200w. It has nothing to do with the cabinet design, it just shows that the driver mechanical limit is lower than its thermal limit. That's not the least bit unusual. For that matter prior to roughly 20 years ago it was the rule rather than the exception. Want to know why vintage drivers were so poor with respect to bass? This is the maximum SPL of the ubiquitous Jensen C12N, which were in my '65 Bassman. If all you looked at was Pe then the 50w rating would seem adequate. Leo Fender certainly thought so. But with 1mm xmax it was mechanically limited to 5w at 60 Hz. 😲

It's not about increasing the power, it's about reducing the peaks in the response that are heard as distortion. Think of it as a fuzz box in reverse, making the tone sound clean at higher levels than it otherwise would. In the case of the OP it could well be that what seems to be speaker distortion is actually the amp hard clipping.

I don't know about GK but TC uses compression and other DSP tweaks to approximate valve transfer function with their RH amps, with power ratings of what they claim they sound like, as opposed to what they measure, leading to the 'TC Watts' scandal. The RH 750 is actually only 236 watts 'but it sounds like 750'. 🤔

Myth. A decibel is a decibel, no matter what the source. The primary reason why valves sound louder is the compression inherent with valves. Duplicate that compression, and all the rest that results in the amp transfer function, and SS amps of any class will sound the same as valves. Said compression and the rest takes place in both the pre-amp and power amp stages, so using the same pre-amp into different power amps will give different results. Valve compression results in easing into clipping, SS without an external compressor doesn't. That can result in very different results even when the power output and decibel levels are identical.

The dip on the maximum SPL chart is where xmax is reached. Since the 320 has considerably longer xmax it also has higher maximum SPL at those frequencies where xmax , rather than thermal power, is the limiting factor. You really don't want that dip in the 60-90 Hz range, as that's where the output demands of electric bass are the highest.

The speaker power rating is the maximum, not the minimum. For that matter the 600 watt rating is thermal. Chances are it may not handle anywhere near that before reaching its mechanical limit. I'd make sure that something's broken before trying to fix it.

+1. In the same box tuned to the same frequency the 12 PR 320 has the advantage in low frequency sensitivity (first chart) and maximum SPL (second chart).

The 320 has lower Fs and longer Xmax, better for the low end output.

An octave pedal is what you use if you really really want to blow drivers. 🤥

Agreed. By the same token if you don't like the sound of what you have don't try to improve on it by adding another cab. Start off with something you do like.

Those look like OEM versions of the 12PR300, so it's highly unlikely they were at fault. The PR320 isn't much better, if at all. You'd have to go FH520 for that. I'd have the old ones re-coned.

True, but there's a lot more to it than the power to each driver, depending on the frequency response and sensitivity of the 2x12 versus the 1x12. The right way to do it is to get a 1x12 extension that uses the same driver with the same enclosure configuration.

That thump is normal, more or less. Better quality amps don't do that. Pulling the plug would be a bad idea if it's 1/4 inch, as that could short the output when you plug it back in and cause serious damage.

Duplicating high and low frequency shelving and midrange bandpass EQ with graphic isn't exactly intuitive, but if you know how they differ it's not all that difficult. However I'd venture that for the average player Q is just a character on Star Trek Next Generation. ☺️

+1, twelve total bands of EQ beats three bands of EQ every time. One just has to know how to use it. The ELF EQ centers are at 80 Hz, 400 Hz and 4.2 kHz, so approximating the same tone with the Peavey wouldn't be all that difficult.