vintage Toho Full range speaker

TOHO vintage 10″ full range speaker

I found a pair of 10″ vintage full range speakers last year, in my friend’s garage. the pair of speakers looks like early Japan made and I can’t find any further info about this driver on internet. The model printed on its magnet shows 10P-H2. One of my friend told me that its ceiling speaker in early day but I’m not sure because of its size, most ceiling speakers are smaller than 8 inch I think.

Whizzer cone looks a little fragile, but still intact, and I can’t remove the magnet cover so I don’t know what type of magnet used. I can feel its very light in weight when I hold it in hand.

I used a signal generator, some resistors, power amp and T/s calculator in Weber webpage and then a oscilloscope to measure T/S parameter, the result shown as below:

Fs=45 Re=7.1 Qes=1.18 Qms=8.65 Qts=1.03 Vas=135L Sd=346

SPL=93dB /1m/1w

From T/S Parameter shown above, and Bl around 5++, I suspect it used Alnico Magnets, and the Alnico seems lost its partial magnetic charge, I will try to re-charge the Alnico if I can remove the cover without damage it.

Toho vintage speaker

Anyway, Qts at around 1 will be the best driver for open baffle. Maybe I can try to mount it on a temporary panel to check its sound quality.

Voice coil seems very small, Obviously, with only 10 watts of ratings means it only suitable for small amplifier such as 2A3 single ended amplifier, or my favourite 6C45Pi Spud Amp.

I listen to bare unit without any panel or cabinet, sounds promising and no weird peaks compare to some of my other drivers.I need to run-in for many hours to decide if its suitable for my audio projects. Hopefully I can use it for a decent open baffle speaker design.

Please check my 2A3 and also ACA amp video, I use this to test run those amps and it sounds good.

Please stay tuned .

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