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Old Audio Tube Amp

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6/20/1999 7:43 PM

Old Audio Tube Amp

I found an old tube amp at a flea market that I bought. On the back it reads:

Model HF-20 Audio Amplifier

Electronic Instrument Co., Inc. L.I. City, 1, N.Y.

There is an out for tape and two inputs labeled phono 1 and phono 2. Someone installed a jack in the back for a speaker out. The transformer is tapped for 4, 8, 16. The person connected the jack to the 8 ohm tap. He/she also put in a mike input and installed another preamp tube (can't read the tube) for the mike gain stage. The origanal tubes are labeled on the top face of the chassis. One 5AR4, Two 12AU7's, Two 12AX7's, Two 6L6's, and the added mystery tube. The cover for the OT is huge, but I don't know how big the actual OT really is.

Anyone know anything? Would this be a good project for a guitar head?

I also have a chassis with transformers and choke from a '69 or '65 Traynor bass head. Anyone do anything with that model?

6/20/1999 11:26 PM

The Amp you described was made by Eico in 1958. Eico stood for Electronics Instrument Company and there HF-20 amp had the tube line-up you described with the exception that the 5AR4 was probably a 5U4 when purchased new. The HF-20 is rated for 20 watts output. The circuit is a Williamson Ultra-Linear type meaning that it was designed really for non-distorted high fidelity rather than the kind of distortion that you may want to get from a guitar amp.

6/20/1999 11:44 PM
Marc	John: Both sound like nice pieces! I think Triode electronics has the HF-20 schematic... and the Traynor is Canada's answer to Marshall the iron should be VG quality and worthy of making music again! Marc

6/21/1999 8:26 PM
Doc	For the HF-20 schematic, try the EICO site, "www.users.interport.net/~fiddler/EICO/HTM". Most (or maybe all) Traynor transformers were mfd by Hammond, so you know the iron's good and the ratings are conservative. Come to think of it, you rarely find a Traynor with a blown transformer.

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