Eico HF-20 Integrated tube amp/mono system

hunter00

Super Member
Just got my Eico hf-20 mono setup going with a period correct University S-8 single speaker.
The Eico needed some recapping ,left the multi cap cans alone as they seem fine just replaceing some electrolytics.Always wondered how these old universities would sound with a single tube amp driving them and while far from my best systems they still sound quite detailed and quite non fatigueing to listen to.
Im going to runs this for a while and see if it wears on me...

hunter
 

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Nice! I like MONO systems. I had a few HF-20s a while back and really liked them too. Happy listening. :music:
 
thx TC
Had the hf 20 running over 10 hrs yesterday to work in the new caps and get a feel for the mono sound.
At first I wasn't all that impressed as I used my ipod for source and know all the songs so well I was picking up the lack of stereo separation/2 channels.
As the evening progressed I began to dig the mono sound more.
I was detecting a bit of lack in bass were the c15w university is supposed to realy excel in so I pulled the front baffle piece that hides the bass driver that made a huge difference!

hunter
 
heres pic of the university s-8 without the bass driver baffle
TC did you ever attempt to bypass the front end on the hf-20's and use them as mono blocks.I may give that a try if I score another unit.

hunter
 

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Sweet little amps, ain't they?

Got an HF12A a bit back and am using that to drive a center channel on my old school quad. It's still mono if you ignore the other four channels, right? <G>

eico-hf12a.jpg


Very clear and crisp with some NOS Sylvania installed. These ol' timers can really sing.
 
your right they do sound detailed and they punch ubove their wpc rateing in my opinion.Im using vintage Sylvania fat bottles and mullard 12ax7 in my unit very impressed.
Just hooked up a single IMF als40ii speaker and im floored by this eico sounds just as dynamic as my old Dynaco mkiv mono's.I know someone with a second hf-20 so im gonna pursue it as ive got a couple spare tube preamps siting on the shelf at the moment
by the way that hf 12 a is clean looking,nice piece!

hunter
 
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Problem with two integrated monoblocks is balancing them properly. Apparently, someone else is already ahead of us on that ... might be worth taking a peek at the solution:

http://tronola.com/html/hf-20_monoblock.html

Not that I'd see it as an issue ... using the HF20's pre controls would just give an extra level of adjustment for matching the room? Surprised how much effect the tone controls have when it comes to simply matching the output of the center channel here to that of the big boxes on the main channels.

Truth be told, I picked the HF12a more for it's size than anything ... it tucks right into my system nicely.

eico-hf12a-bose.jpg


Not that I'm complaining about the exceptional sound. I drive the Bose VS100 just below it using the center channel (L+R) tap from the Carver H9AV you can see peeking out from under the dbx expander. The integrated pre of the HF12a is perfect for the setup. I also balance it with the rear channels with the front channels off ... those are driven with the other tube amp. Once that's on, I cut/boost those to match the ground pounders for a good blend.

(and ya, it IS purty, ain't it!)

PS ... as far as punching above their weight, the HF12A is rated 12 watts (obviously) from a pair of EL84's, but tack in at 18 watts using the heavy duty 7189. I've got a pair of TAD EL84STR's (7189 equivalent) that will really crank it, but I prefer the sound of the NOS Sylvania's ... not sure if your HF20 gives you any "high performance" tube options?
 
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Nice setup Skizo.I tryed the center channel off my HHscott LC-21 preamp with the big university speaker and it provided a large soundstage but I found it messed with my separation ,I pulled it for that reason.
If I can pick up another hf20 ill run it with the preamps in and see how I like it.Its an easy mod to turn them into mono block which I dig .
Im not sure about"high performance tube options" either as there just new to me and I haven't rolled tubes in it yet.
I sold my dynaco mkiv monos last yr and have been missing having a second pair for my bedroom system
I need to find another electically hf-20 pooched then I will be set...this one only cost me 100.00 bucks.

hunter
 
Took a peek at the schematic, and it looks like either a KT66 or 6550 should work in your amp. That opens up a lot of possibilities - IF they'll fit. Bottle's a bit bigger, but looks like space isn't an issue on the HF20. KT 88 maybe, but not sure if the iron's strong enough to drive those.

Here's a good chart on what you can do with the drivers ...

http://cydathria.com/fdm/12AX7_sub.html

Those will make the biggest difference in the tone and feel of the sound. Lot of that is brand related too. There, the old school RCA and Sylvania tend to get the best reviews in home audio. Careful what you read, as a lot of that is about instrument amps, and that's a whole nuther ballgame, eh.

Nice piece though ... have fun with it!

PS ... center channel, as with a lot of things, is all about moderation. You've got the right mix if you settle back and can't hear it until you turn it off. That should get you to where you're getting max impact without reducing the stage.
 
Took a peek at the schematic, and it looks like either a KT66 or 6550 should work in your amp. That opens up a lot of possibilities - IF they'll fit. Bottle's a bit bigger, but looks like space isn't an issue on the HF20. KT 88 maybe, but not sure if the iron's strong enough to drive those.

Here's a good chart on what you can do with the drivers ...

http://cydathria.com/fdm/12AX7_sub.html

Those will make the biggest difference in the tone and feel of the sound. Lot of that is brand related too. There, the old school RCA and Sylvania tend to get the best reviews in home audio. Careful what you read, as a lot of that is about instrument amps, and that's a whole nuther ballgame, eh.

Nice piece though ... have fun with it!

PS ... center channel, as with a lot of things, is all about moderation. You've got the right mix if you settle back and can't hear it until you turn it off. That should get you to where you're getting max impact without reducing the stage.

thx for the link.It would be nice if I could use 6550's as I have a few extra matched quads of 1960's tungsols for my HHscott LK-150.
I will have fun guaranteed thx again

hunter
 
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