25-04-2022, 03:54 PM
With no model number, you'll struggle to find anything (the numbers on the gasket and diaphragm are probably not model numbers).
First, what are your expectations? It's clearly not hi-fi. And I wouldn't expect it to last long as a guitar amp, given that it'll have a paper voice coil former and ancient glues. What is the diameter of the voice coil - 3/4", perhaps? I wouldn't put more than 5 watts into that, honestly. Perhaps OK as a practice amp fed from a 1 or 2 watt transistor radio amp, but definitely not for stage use. I'm guessing it was originally intended for use in a large radio or radiogram.
If you wanted to use if for a guitar practice amp, just bung it in a typical open-back cabinet. But if you want to use it more seriously, you'll have to measure the T/S parameters: https://en.wikipedia.org/wiki/Thiele/Small_parameters
Don't let that article put you off - you only really need Fs, Qts and Vas to be able to design a box for it. There's lots more detail here, including a spreadsheet that helps you with the maths: https://sound-au.com/tsp.htm
With those parameters, you can design a sealed or ported box. That is simple today - use something like WinISD to do the maths. Back in the '80s I did it by hand - the maths isn't hard (it couldn't have been, because I was able to cope with it!).
Next, you'd need to measure the acoustic output of the drive unit to determine how it'll sound, and what sort of crossover you'll need. That's more tricky, but I seem to recall that you do have the kit for that. I'm not expecting an especially smooth curve from something like that. It'll become very directional about about 1.5kHz, give or take, so crossing over low will help.
Oh, and if you're tempted to tackle the rust, be careful that nothing gets in the magnetic gap. I'd probably just paint on a bit of Kurust or similar - rubbing it down would be too risky IMHO...
First, what are your expectations? It's clearly not hi-fi. And I wouldn't expect it to last long as a guitar amp, given that it'll have a paper voice coil former and ancient glues. What is the diameter of the voice coil - 3/4", perhaps? I wouldn't put more than 5 watts into that, honestly. Perhaps OK as a practice amp fed from a 1 or 2 watt transistor radio amp, but definitely not for stage use. I'm guessing it was originally intended for use in a large radio or radiogram.
If you wanted to use if for a guitar practice amp, just bung it in a typical open-back cabinet. But if you want to use it more seriously, you'll have to measure the T/S parameters: https://en.wikipedia.org/wiki/Thiele/Small_parameters
Don't let that article put you off - you only really need Fs, Qts and Vas to be able to design a box for it. There's lots more detail here, including a spreadsheet that helps you with the maths: https://sound-au.com/tsp.htm
With those parameters, you can design a sealed or ported box. That is simple today - use something like WinISD to do the maths. Back in the '80s I did it by hand - the maths isn't hard (it couldn't have been, because I was able to cope with it!).
Next, you'd need to measure the acoustic output of the drive unit to determine how it'll sound, and what sort of crossover you'll need. That's more tricky, but I seem to recall that you do have the kit for that. I'm not expecting an especially smooth curve from something like that. It'll become very directional about about 1.5kHz, give or take, so crossing over low will help.
Oh, and if you're tempted to tackle the rust, be careful that nothing gets in the magnetic gap. I'd probably just paint on a bit of Kurust or similar - rubbing it down would be too risky IMHO...
