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Eico HF 81 VS Dynaco St 35 DG Style?

Tubeglowpio said:
500k dual center tapped at 250k Linear, would be awesome if you have one
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Here’s the closest thing in my box of parts,:

it’s a 250k, however it’s a short shaft, I’ve made shat extensions but don’t have one right now....

With digital ohm meter the front (close to shaft) Measures a max of 254k, the rear maxed at 268k

The two bottom maxed at 200k

On both my meter and with an Oscilloscope, turning the knob, was very smooth and progressive

For some reason I didn’t label what this came out of, but here are the numbers:

HR4040 177254

1346515 250k

it’s very clean looking but I probably never took it apart to clean

you can start a conversation if you want it all I ask is shipping cost (USPS Priority) that way I’ll just print a label....




7EB283A9-21B0-4576-90CE-F46B5496748C.jpeg 87AB6C5F-261D-4840-9A11-4FF2A1CD7F99.jpeg 0C1FA9D2-C78A-40FB-8D24-5C7514F06064.jpeg D8E4DDFD-BF5B-4383-A132-1286C71FDE22.jpeg 7C4062A7-EF9F-48DB-9297-467BE1D11BF2.jpeg 7EB283A9-21B0-4576-90CE-F46B5496748C.jpeg
 
adnick said:
Here’s the closest thing in my box of parts,:

it’s a 250k, however it’s a short shaft, I’ve made shat extensions but don’t have one right now....

With digital ohm meter the front (close to shaft) Measures a max of 254k, the rear maxed at 268k

The two bottom maxed at 200k

On both my meter and with an Oscilloscope, turning the knob, was very smooth and progressive

For some reason I didn’t label what this came out of, but here are the numbers:

HR4040 177254

1346515 250k

it’s very clean looking but I probably never took it apart to clean

you can start a conversation if you want it all I ask is shipping cost (USPS Priority) that way I’ll just print a label....




View attachment 1917867 View attachment 1917869 View attachment 1917870 View attachment 1917871 View attachment 1917872 View attachment 1917867
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Really appreciate you looking but would like to keep it at the original 500k so I don't limit my treble control range, if you don't get or make some extensions I would happily buysome.
 
Dandy said:
It is hard to relate John Atkinson's negative view of the measurements to Peter Breuninger's ecstatic listening review. There ought to be some correlation or explanation. I seem to recall Dave Gillespie talking about this in an earlier thread. It's something to do with circuit synergy.
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Many of us choose to build amps with less than perfect parts to get a special sounding unit, distortion can be our friend if its the right kind and right amount.
 
Understood....My thinking was if the 500k can’t be had, then use a 250k with a resistor on one side and see how it sounds....

Actually hadn’t thought about shaft extensions in a while, how many do you need? Have several projects at the moment, but I’ll keep it in mind....

Andy
 
adnick said:
Understood....My thinking was if the 500k can’t be had, then use a 250k with a resistor on one side and see how it sounds....

Actually hadn’t thought about shaft extensions in a while, how many do you need? Have several projects at the moment, but I’ll keep it in mind....

Andy
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Yeah could experiment but the pot is not the easiest to get to if I can remember and is connected to tone ic package pec which I should rebuild on some protoboard soon. 10 would be a good number as I'm sure I could use some on my other amps too like my voice of music amp I think, thanks.
 
regore said:
John Atkinson did an in depth review in Stereophile on the Eico HF-81 on June 2, 2006. It's still available online because I just read it. This amp has such terrible specs. only an audiophile could appreciate it. Read the review to fully enjoy the miserable specs. and high distortion this amp can produce. Two amps were fully restored by professionals before testing was done. Hard to believe how many people still hold this amp in high regard.
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I have an Eico HF-81 that I had restored/upgraded by Dan Nicotera. Every time I put that amp back on it surprises me how nice it sounds. I too read John Atkinson's review of the specs and measurements of the amp. It's surely not the best amp, I'm sure the output transformers don't have the best measurements from 10hz to 20khz, but it really does sound nice to me with an excellent sound stage and pretty good separation and clarity. Unfortunately I'm getting a bit of buzzing in mine that I'll have to have someone chase down. One thing that helps is to put in a better tracking volume pot, remove the "focus" knob from the circuit, and to mount the on off switch at the tape switch, so you don't have to constantly reset the trebel volume when turning the amp on.

Best,

Jonas
 
I've owned two SCA-35 and a HF-81. I thought all of them sounded good, although I am much more a fan of separates than integrateds.

The HF-81 was not restored and I hated the various odd knobs & controls. It was a pain to get it set up right. If I had had the skills, I would have kept it and restored it. For even being quite old, it had a wonderful midrange.

I would like to hear a restored ST-35 with Dave's boards. That sounds like an audio treat. Would be tempted to buy one, even though I have no need at all for a 6th tube amp, especially yet another one producing less than 20wpc. I would not be surprised if one of these bested the HF-81.
 
There is a really nice hf81 on eBay right now. I suggest someone buy it and find out what all the fuss is about. I love the sound of my st35. It almost beats the Heathkit and pilot el84 offerings.
 
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