Originally Posted by
Simon Barden
The wooden box itself has no rating, so you can fit whatever rated speaker you want and the cab rating will be 4 x whatever the speaker rating is. This will give you a lot more flexibility in driver choice. I’d suggest each driver be rated at least at 100W, for a minimum 400W cab rating, as your amp will produce well over 200W if driven hard, probably nearer 350W if distorting. The ear is less sensitive to bass frequencies than mids, so you need more watts to drive the speakers to get the same apparent volume. So you’ll probably find that you have to turn up the amp a lot more than you normally would.
The driver impedance is also your choice. Peavey chose 8 ohms because it was designed to work with their transistor bass amps, and an 8 ohm 4x10” cab and an 8 ohm 1x15” cab would provide a 4 ohm load for the bass amp, giving maximum power output for the amp (compared to an 8 ohm or 16 ohm load). Used with a valve amp, the impedance rating doesn’t really matter as long as there’s a tap for it on the amp’s output transformer.
95% of bass amps are solid state, so almost all bass cabs will be 8 ohm rated to give 4 ohms when paired with another cab. So 8 ohms would be a good choice if you plan to add another standard bass cab and you don’t plan to swap out the speaker. But 16 ohms is a slightly better choice for a valve amp speaker, as you could then pair it with say a 16 ohm Marshall 4x12” cab.
Driver frequency response needs to be considered as 10” speakers can be very mid-biased. Your amp has passive tone controls, unlike a solid state bass amp which will have active tone controls, so whilst you can cut mids and treble, you can’t boost the bass to make up for a lack of response if the driver’s frequency response isn’t great at bass frequencies. So compare the frequency graphs and think about the response around the 40-80Hz region, where the bass fundamentals will be and compare them to the mid response levels. The bigger the difference, the more mid-forward and boxy it will sound.
It’s not a PA cab, it’s definitely a bass amp cab. The crossover is there for the centrally mounted HF tweeter. That may be a piezo unit, a compression driver or even a small diameter standard driver. There's often an on/off switch for that or maybe a level control. Something you’d want out of circuit if you ever used the cab for guitar used with distortion, and you’d then want the crossover out of the signal path completely.
If you want to have it a dual purpose bass/guitar cab you’d be better off removing the crossover and disconnecting the HF driver, (maybe remove that too and blank off the hole). Unless you are playing a lot of slap bass or a lot of high notes, then you won’t notice the loss. It’s not something you need for rock/blues bass as long as there’s no crossover dropping off the high-end. 10” speakers have a reasonable HF response, certainly compared to 15” or 12” speakers.
The cab doesn't appear to be ported at the front, so unless there’s a rear port, there’s no need to consider the TS parameters fir tuning and getting a speaker that closely matches the originals. If there is, then you’ll probably want to get the same drivers if possible, though that may prove to be expensive.
Do you know the cab model ref, as the literature may give a frequency response, which will indicate how good an all-round cab it is, or whether it really was mid-biased and should be used with a 1x15” to fill out the bottom end.
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