NOSValves Posted March 31, 2002 Share Posted March 31, 2002 Thought I would post this for anyone that might be interested. Clean looking units. Linkage Quote Link to comment Share on other sites More sharing options...
Clipped and Shorn Posted March 31, 2002 Share Posted March 31, 2002 The HF-20 amp section is supposed to be quite good, but then you have a not so good preamp in each unit that you would need to bypass in favor of a better stereo preamp? This is what I have heard. Anyone have experience with these units? -fused and refused ------------------ Cornwalls currently upgrading to all tube components Quote Link to comment Share on other sites More sharing options...
NOSValves Posted March 31, 2002 Author Share Posted March 31, 2002 Mdeneen I did the Grounding you suggested with almost no improvement. Its a dust pan special and I'm not going to touch it till you do the benching on Klipped HF-81 and see if its worth the effort. Craig This message has been edited by NOS440 on 03-31-2002 at 12:51 PM Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted March 31, 2002 Share Posted March 31, 2002 These use to be DIRT cheap and some of the favorites for people modding as you can turn them into anyhing... It's another Williamson circuit(one of the all time classics). The output transformers are very nice as stated elsewhere; indeed, these EICO amp outputs are rated 20hz-20khz and higher and are extremely linear. As stated, the vintage EICO iron is some of the best, from top to bottom. I am not a big measurements believer as I have seen poor measuring amps sound magical, but these vintage EICO pieces were very nice on the bench (HF-20,22,35,50,60,87/89 as well as the series around the 6BQ5/7591). Here is a picture of a lad's HF-20 he changed to push-pull Sovtek 6B4G Directly Heated Triode amps. He obviously took some time on the chassis as well. Too bad he opted for the SS rectification although he used HEXFREDs. I still find that tube rectification is more harmonically open and smooth. OF course, a choke is needed to really do the job correctly. The HF-20 output tubes can be reconfigured a variety of ways. kh ps- NOS, please sell your HF-81 to Bob for a reasonable price so someone can appreciate it. From what he tells me, he knows his way around a soldering iron as well. Phono Linn LP-12 Vahalla / Linn Basic Plus / Sumiko Blue Point CD Player Rega Planet Preamp Cary Audio SLP-70 w/Phono Modified Amplifier Welborne Labs 2A3 Moondog Monoblocks Cable DIYCable Superlative / Twisted Cross Connect Speaker 1977 Klipsch Cornwall I w/Alnico & Type B Crossover system one online / alternate components / Asylum Listing f>s> This message has been edited by mobile homeless on 03-31-2002 at 01:48 PM Quote Link to comment Share on other sites More sharing options...
Clipped and Shorn Posted March 31, 2002 Share Posted March 31, 2002 Seeing the beautiful job someone did on the HF-20 that mobile posted puts that amp in a whole other light. The ones on eBay look pretty clean and the price is not bad at the moment. I guess it is common knowledge to just eliminate that preamp section. -chromed and domed ------------------ Cornwalls currently upgrading to all tube components Quote Link to comment Share on other sites More sharing options...
SOUNDJUNKIE Posted April 1, 2002 Share Posted April 1, 2002 Mdeneen writes: ...And what are those 1/4" jacks for? Seem to have been added aftermarket. B'DAY AND SHOWER GIGS?? Makes me wonder what's under the hood. Quote Link to comment Share on other sites More sharing options...
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