Eico HF20 conversion

[navdave]

A buddy of mine came accross an old Eico amp.
He wants me to convert it into an Orange GRO amp.
I want to convert it to grid bias instead of cathode bias,
and use a GZ34 rectifier instead of a 5U4. So my question
is can the stock output transformer handle the extra voltage
and power demands?
http://www.acousticpsychos.com/Files/Eico/EICO_HF20S_SCHEMATIC.GIF

[stingray_65]

I'm curious as to why you want to swap recto tubes?
Higher B+?

And you plan on using just the 2 p-p 6l6's and not a quad like the GRO 100 right?

The Eico OT looks massive! and potted to boot, so say in fixed biased, and what 450V at B+ you would be in the 50-60W range.

That's a far cry from the rated 20 W 36peak the Eico is rated. BUT it's generally considered under rated.

In general,(personal opinion here) old HiFi OT's don't make great guitar amp OT's. I do like them for bass amps tho.

[navdave]

Yes I wanted a higher B+ because I am trying to squeeze
at least a good 50 watts out of this thing I like you noticed
the large OT this thing is sporting so I figured give
It a try and hope it can handle it. As far as UL go's I'm
Fine with it the original GRO used an ultra linear
Output transformer as well.

I'm curious as to why you want to swap recto tubes?
Higher B+?

And you plan on using just the 2 p-p 6l6's and not a quad like the GRO 100 right?

The Eico OT looks massive! and potted to boot, so say in fixed biased, and what 450V at B+ you would be in the 50-60W range.

That's a far cry from the rated 20 W 36peak the Eico is rated. BUT it's generally considered under rated.

In general,(personal opinion here) old HiFi OT's don't make great guitar amp OT's. I do like them for bass amps tho.