Dummy load for unknown output impedence

ALustyGhost · 31st October 2008, 07:26 PM

Should be safe to build a 16 ohm dummy load, right? I've got a 1950s Japanese portable reel to reel with a little 2" speaker in it. The belts and rollers are shot, and it's not good enough to be worth fixing, so I just replaced the play head with a 1/4 jack so I can use it as a small amp, which works fine, but I'm thinking it would be a lot more useful with a dummy load so I can use it for distortion and route it to a regular amp. I have no idea what the speaker's impedence is, and more interestingly, there is NO OUTPUT TRANSFORMER whatsoever, which is a new one to me.

Nigel Goodwin · 1st November 2008, 07:37 PM

Is it transistor or valve (tube)?.

ALustyGhost · 2nd November 2008, 09:08 PM

It's tube, but I'm thrown off by the fact that it only has one transformer, which appears to be power supply.

Geek · 2nd November 2008, 09:41 PM

Quote:

Originally posted by ALustyGhost
It's tube, but I'm thrown off by the fact that it only has one transformer, which appears to be power supply.

It's likely a line operated device then and that's the output. Bad Karma

Even transistor circuits of the era had OPT's.

ALustyGhost · 2nd November 2008, 10:23 PM

It's working fine as a self-contained amp as is, I'll just keep it that way and record with it occasinally, along side my old tube Wollensak.

31st October 2008, 07:26 PM	#1
ALustyGhost diyAudio Member Join Date: Jun 2008	Dummy load for unknown output impedence Should be safe to build a 16 ohm dummy load, right? I've got a 1950s Japanese portable reel to reel with a little 2" speaker in it. The belts and rollers are shot, and it's not good enough to be worth fixing, so I just replaced the play head with a 1/4 jack so I can use it as a small amp, which works fine, but I'm thinking it would be a lot more useful with a dummy load so I can use it for distortion and route it to a regular amp. I have no idea what the speaker's impedence is, and more interestingly, there is NO OUTPUT TRANSFORMER whatsoever, which is a new one to me.

1st November 2008, 07:37 PM	#2
Nigel Goodwin diyAudio Member Join Date: Jul 2005 Location: North Derbyshire	Is it transistor or valve (tube)?. __________________ Nigel Goodwin

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2nd November 2008, 09:08 PM	#3
ALustyGhost diyAudio Member Join Date: Jun 2008	It's tube, but I'm thrown off by the fact that it only has one transformer, which appears to be power supply.

2nd November 2008, 10:23 PM	#5
ALustyGhost diyAudio Member Join Date: Jun 2008	It's working fine as a self-contained amp as is, I'll just keep it that way and record with it occasinally, along side my old tube Wollensak.