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EICO HF-20 Guitar Amp Convert
EICO HF-20 Guitar Amp Convert
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Old 5th February 2009, 03:45 PM   #1
topGimme is offline topGimme  United States
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Default EICO HF-20 Guitar Amp Convert


I have a working EICO HF-20 tube integrated amplifier. Its in great shape, and sounds real good! I have all the original paperwork (manual, schematics, templates, etc...).

"Real" tube amps are very, very expensive as are tube amp kits. I am hoping to convert/rework the #20 into a guitar amp. PHONO 1 is set up for magnetic cartidge type input, so I think converting a #20 is feasible as per “Converting Integrated/PA Tube Amps into Guitar Amps” by Joe Jasniewski (http://www.rru.com/~meo/Guitar/Amps/...tar/index.html)a

I've attached the #20 schematic. I can email a better quality file, but cannot post due to attach file size limitations. I can also provide any other original documentation if necessary. Can someone please offer specific instructions for how to re-wire the input and tone 'grids'? As per Mr. Jasniewski this is all that is necessary. Future more complex mods are possible, but to begin I want to take one step at a time.

I had some exposure to electric circuits in college (building rectifier bridges, learning to use an oscilliscope, etc...). I think I can safely rework this with a little help.

Thank you
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Old 5th February 2009, 03:52 PM   #2
Tom Bavis is offline Tom Bavis
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I suggest you sell it and use the proceeds to buy and modify a PA amp (you could buy SEVERAL Bogens, S-Cs, etc. for what the HF-20 will bring...). They're actually better suited to the purpose anyway.
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Old 6th February 2009, 12:44 AM   #3
rickl is offline rickl  United States
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Please listen to Tom's advice. The Eico is not the amp you want to convert to a guitar amp.

Not sure what kind of amp you want (Champ clone, Showman clone) but if you want to build a guitar amp, post what you want and someone can help.

I've built several different guitar amps (Champ from parts, Deluxe from a broken Knight, Princeton from a old tube record player, ...).

The Eico is not a guitar amp.

Listen to Tom.
searching for jazz and a little libations.
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Old 6th February 2009, 08:58 PM   #4
topGimme is offline topGimme  United States
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Default EICO HF-20 Guitar Amp Convert

Thanks for the advice! I though all you needed to get a good conversion were enough gain stages as in magnetic phono input.

You are right. I also thought about selling the whole lot on ebay. I also have the original tuner, and a basket full of replacment valves. Maybe worth $400-$500 altogether?

Then, I could instead get a ready made amp kit to satisfy my curiosity. I may also wind up with a much better result.

However, tube amp kits are NOT cheap, and at least half a dozen internet sites are selling all different kinds. Any advice recommendations regarding this alternative?

Thanks again! Have a great weekend!
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