Deang Posted June 9, 2002 Share Posted June 9, 2002 Kelly, I was really just making a half-hearted jest. I was inferring that in order to get the sonics the AE-25 gives me at full tilt -- I would probably be constantly pushing the EICO past its safe operating limits. Of course, I realize that there really ain't squat difference between 8 watts and 15 watts in the real world. ------------------ Deanf>s> Cary AE-25/ S F Line 1/ S9000ES/ HSU x-over/ SVS CS+/ RF-7 Klipschcones®f>s> Exigency is the matriarch of ingenious contrivancef>c>s> Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted June 9, 2002 Share Posted June 9, 2002 EICO is actually rated an easy 14w per channel but sounds much more powerful. I think it does well throughtout its volume range but it does like to be turned up to around 5 o clock or so to bloom fully. kh Quote Link to comment Share on other sites More sharing options...
Deang Posted June 9, 2002 Share Posted June 9, 2002 Where did I get 8 watts from? Who knows. Whoa, 14 watts. Killer ------------------ Deanf>s> Cary AE-25/ S F Line 1/ S9000ES/ HSU x-over/ SVS CS+/ RF-7 Klipschcones®f>s> Exigency is the matriarch of ingenious contrivancef>c>s> Quote Link to comment Share on other sites More sharing options...
John Warren Posted June 9, 2002 Author Share Posted June 9, 2002 leok- the HF-81 is an all-triode, non-ultralinear Williamson circuit. It was marketed by EICO as a Stereo Intergrated Williamson amp. Outputs are cathode-biased push-pull EL-84s. Single steel chassis construction, straightforward assy for the DIYer. a nice little amps for the den, rec room or wood shop. puts out an honest 14wpc, lacks real low output and make noise when they operate. I see them at hamfests all the time. got a Heath WA-P1 an earlier Williamson version based on the STANCOR OT. The amp uses 807s instead of KT-66s, first two stages use R-C power-supply filtering. It's a yawner. I've got a Scott version around here too. It needs tubes and I'd rather spend my money of JBL pro drivers. I just bought (8) 2123Js from the JBL tent sale, a pair of Community compression drivers and horns and I'm build two pairs of 3-way networks using some pricey "audiophile" components so tubes are out this year. glad you liked the Stan White article. forgot to mention I'm going to drive the 2123s with a Mc2500 (that's 1.2kWs of pure SS muscle) This message has been edited by John Warren on 06-09-2002 at 08:28 PM Quote Link to comment Share on other sites More sharing options...
Deang Posted June 9, 2002 Share Posted June 9, 2002 John, What kind of shape do you usually see the EICO's in at your hamfests? Any idea about how much they run? ------------------ Deanf>s> Cary AE-25 * S F Line 1 * S9000ES * HSU x-over * SVS CS+ * RF-7 Klipschcones® f>s> Exigency is the matriarch of ingenious contrivancef>c>s> This message has been edited by deang on 06-09-2002 at 08:43 PM Quote Link to comment Share on other sites More sharing options...
John Warren Posted June 9, 2002 Author Share Posted June 9, 2002 chassis are rusted, knobs missing, OT missing, no tubes, the usual condition. $50-100 is the range. find a ham radio type and ask him/her where and when the next hamfest is. Quote Link to comment Share on other sites More sharing options...
leok Posted June 10, 2002 Share Posted June 10, 2002 deang, Transistors in pairs, some form of class B operation, is the most significant cause of low level "crossover" distortion, but the fundamental control mechanism of a bipolar device is exponential. As more is demanded of the transistor from a voltage control source, the transistor tends to respond with with current gain that is a square of the voltage "error" or "control" signal rather than a simple multiple. As the signals get smaller (musical detail) this property becomes more predominant in the response of the circuit in which the transistor is used. I have tried to design transistor amps, but can't avoid this low level exponential property. Good designers can, and that's why they get the big bucks. FETs are not so fundamentally exponential, but they must be used in a control circuit, which uses feedback. The feedback debate is endless. But in short, feedback can be noisy. It creates a noise floor limiting detail capability. Again, good designers can handle this stuff. I'm sure a really good transistor amp is wonderful. I just can't afford one that's good enough for my RF-7s. For Magneplaners, it wouldn't be so hard, but for Klipschhorns or RF-7s, it is hard. leok Quote Link to comment Share on other sites More sharing options...
leok Posted June 10, 2002 Share Posted June 10, 2002 John, I just noticed your post. I guess I'll have to find that HF-81 schematic. Maybe I'm confusing it with another design. I was sure the input was pentode, well maybe not. I'll do some research & get back. So what DO people like about the HF-81? Maybe that small output transformer does it. Hey, deang, would you do us a favor and rip the output transformers out of your Superamps and try Hammond 1608s to see if the high end and detail improves? No? Why not? leok Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted June 10, 2002 Share Posted June 10, 2002 Leok, the HF-81 is an ALL TRIODE front end (unlike a host of other integrateds, many listed here) with 4 12AX7, 2 12AU7, 2 EZ-81 Rectifiers, and 4 pentode configured EL-84. I do not like this amp as much seperated. My highly modified Cary with Kimber silver wire and Solen/ELNA PS and MIT coupling caps with excellent vintage REd Dot RCA 5691/5692 did not sound as good hooked up to just the amp section as the unit performed as a whole. This was one of the first things I did as I was not a fan of integrated amps since the 70s. This is the sole unit that changed my mind (another preconception that was broken - one of the many with tube amps). I had liked integrateds for my second systems but had never had them in my main. The EICO front end, despite the mediocre tone controls and various selection functions, is DAMN NICE with this unit. No, I would not use it as my main preamp if possible but as a whole, this unit is way more than the simple sum of its parts. Granted, my true Directly Heated Triode SET monoblocks are a whole nother ballgame than the EICO. The openness and transparency combined with the amazing resolution at the same time without any glare or hardness is simply on the next level. Running an amp in triode mode with tubes like EL-34 and KT-88 does not come close to the sound of a well design SET with true triodes with excellent iron run on near 100dB and greater speakers. I have done both. I dont discuss this as much cause it gets tiring to repeat and the specs guys will NEVER believe. SET does not do everything perfectly, but what it does do betters any amplifier I have yet to have in my system. And I have had quite a few pieces. kh ps- If you want to take a look at the schematic, go here: http://home.earthlink.net/~eico_hf81/schematic/eico_hf81_schematic_full.gif ------------------ 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 06-10-2002 at 11:51 AM Quote Link to comment Share on other sites More sharing options...
esker Posted June 10, 2002 Share Posted June 10, 2002 Has anybody here ever heard one of Stan White's Powrtron amplifiers? Quote Link to comment Share on other sites More sharing options...
John Warren Posted June 10, 2002 Author Share Posted June 10, 2002 Mark- I was under the impression that the IM distortion for this amp is rated over a narrow bandwith (like 60-10kHz) and is on the order of 2-3% at 2X14W total output. And when measured over 50-12kHz it shows significant strain. The "Audio League" did a review on this amp, I have to find it. mh- I think the Eico is a vintage example of a low cost, high quality audio DIYer amp that was a real novelty in the 50s. ANd I would take it over just about ANYTHING sold by Tweeter today. but I also think that some people think that for $200 and a retube they get a Marantz Model 2 clone. My take on it is it is a nice low powered amp with (by todays standards) limited LF and HF output. my humble opinion. This message has been edited by John Warren on 06-10-2002 at 07:02 PM Quote Link to comment Share on other sites More sharing options...
leok Posted June 10, 2002 Share Posted June 10, 2002 homeless, John Thanks for the schematic. When I went to put it in the logical folder I found what I thought had been it: the Eico hf22. So, John, I have to take back everything I said about the HF-81, except for the transformer size. Yes, I see now, it's a Williamson .. complete with dual impedance phase inverter. Maybe I'll just listen for a while. leok Quote Link to comment Share on other sites More sharing options...
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