Testing a tube amp before investing in it

Takoctopus
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Testing a tube amp before investing in it

Postby Takoctopus » Sat Aug 01, 2015 7:00 am

New to the forum but thought i would ask some advice about an amp i have laying around. Well its a Royal super bunny. Its an all tube 50 watt head from Japan. The problem i have is its missing one power tube and one 12ax7. Its should have 2 6l6s and four 12ax7s. So its missing one of each. I dont have a speaker cabnet for it yet. If i rig up a speaker will i be able to find out if it works basically? Without blowing it up? It does power up but im worried about some load on it. Any advice is welcome. Thanks in advance.

Takoctopus
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Re: Testing a tube amp before investing in it

Postby Takoctopus » Sat Aug 01, 2015 7:16 am


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zarfnober
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Re: Testing a tube amp before investing in it

Postby zarfnober » Sat Aug 01, 2015 3:54 pm

You can power it up to test IF you have a second power tube, I wouldn't with out it. Without seeing the schematic to know what 12ax7 powers what part of the circuit, I'd put one next to the power tubes, and one in the first and second position. Trem and verb usually, but not always, run off the second and third preamp tubes.

Buy or borrow another 12ax7 and 6L6 and try it. Make sure you have a speaker connected, or you'll likely blow the output transformer. If it fires up and hums, it probably has a bad filter cap, and any old amp like that should be gone over by a tech and likely needs the filter caps changed, the a 3 prong power cord.

Is there a tech close by, or a friend that is tube amp experienced? Best of luck, and if you can't get it working, maybe I'll buy it from you. But don't pay a lot for the amp, how much do they want for it?

Rocco
www.rockometeramp.com Vinatge spec American and British style cabs, custom cabs, recovers, regrills and restorations.

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zarfnober
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Re: Testing a tube amp before investing in it

Postby zarfnober » Sat Aug 01, 2015 4:06 pm

One more question, are you sure it takes 6L6 power tubes? The little info I found in a search showed their amps with EL34 and EL84 power tubes.

Rocco
www.rockometeramp.com Vinatge spec American and British style cabs, custom cabs, recovers, regrills and restorations.

Takoctopus
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Re: Testing a tube amp before investing in it

Postby Takoctopus » Sat Aug 01, 2015 6:14 pm

Its an odd amp for sure. The 6L6 could just been thrown in years ago. As far as the power cord goes three prongs are not used here and it still has a two prong power cord. From what i have read here i should just bite the bullet and take it in. I normally use a champ but have never had to any real maintence to it. This amp has the effects i use so it would be nice to toss the stomp boxes. Im not interested in selling it. Its the correct amount of strange for me. Thanks for the advice and will update later after i get it back from the shop.. Thanks again
Ivan


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