Wurlitzer side man Speaker Impedence?

[Newpaltzwonder]

Howdy Everyone,

I have a Wurlitzer side man that is being used as a guitar amp...and I'm looking into replacing the speaker in it with new one.

I've looked everywhere for the speaker Ohm, (yes, I did look on the back of the speaker...it's blank) and I can't find out any information.

I've hooked up my meter to test it, but I'm not fully sure how to test it,....so that was pointless for the moment.

Eventually I would like to hook up two speakers to it, but I don't want to fry the output Trans. in the process....But, I would like to get the most out of the amp.

Any ideas??? Also, I'm looking for any other specs on it...like wattage....and if anyone else has tinkered around with this tube amp.

Any help would be great!!!

Newpaltzwonder

 

[lndm]

Typically, if you measure the DC resistance of the voice coil, the nominal impedance will be 1.25 higher. If your findings are ambiguous, the nominal value is probably an exponent of 2, like 4,8,16.

Paralleling devices into a valve amp doesn't carry the same dangers as overloading a solid state amp. Still it is best to do things right. Running an incorrect impedance will likely increase distortion or limit output.

Try to find different impedance taps on the OPT if you can.

You might guess the power by looking at the output devices. Maybe you would get the spec sheets and compare the recommended application notes.

 

[Newpaltzwonder]

Thanks.....

When I tested it before....I was getting a reading of 2 ohms. That was with the speaker still connected though, I don't know if that will make a difference? I didn't want to turn it on with no load....just in case I was going to kill it.

As for the size of the Transformer, I took the amp over to a shop a few weeks ago, and the guy said that it is at least 50 watts. He showed me a transformer from an amp he is repairing and it was a 50 watt bass amp, and the trans from mine was almost twice the size. But that was a solid state amp, compared to the tube amp I have.

I did get two new Crate speakers...12" SLM 50w 8 ohm speakers, I was thinking that I should wire them for 16 ohm just to be safe, unless I hear otherwise....

If anyone has any suggestions...that would be great!!!

Thanks,

Newpaltzwonder

 

[lndm]

The guy at the shop was probably looking at the power transformer as most solid state amps do not have an output transformer. Typically, valve amp power transformers have heavy gauge heater windings included within so will be larger for the same power.

You need to disconnect your speaker from the amp to measure the speakers resistance. Typically, 8 ohm speakers will measure 6 ohms give or take. When you know, label the opt winding you used.

On averages, I would guess it is likely that your amp will have a 4 ohm tap.

 

[Newpaltzwonder]

Well,

The cabinet is together and the speakers are in, wired at 4 Ohms. I did a test today and all went well, there was a slight hum but I think that can be remedied when I put the amplifier in it's new case. Which is going to be reworked after I felt how much heat is coming off the 6BQ5 tubes...Wow.

Besides, I'm looking into a pre amp that I can use with the Wurlitzer amp. I've been looking at the Tube Pedal on Hoffmanamps.com...seems pretty good. But I'm going to keep looking. I want to go with tubes with the preamp...I'm goofy like that.

I think I'll add a post later on when I have more time to see if anyone has built a tube pedal that is similar or even better.

Thanks for your help.....


Newpaltzwonder