mobile homeless Posted September 1, 2002 Share Posted September 1, 2002 While you can add volume pots to the monoblocks, it is a pain to use, as two controls are needed to be adjusted every time instead of one, with the additional matching required. Also, these would always been in the circuit and I would rather have a preamp of some sort to give more flexibility, whether it be active or passive. I am seriously considering bidding on the HF-14 myself to play with... So no one bid! heh... kh Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted September 1, 2002 Share Posted September 1, 2002 Well, back among the living.... I'm not as dumb as I look, I just mixed up the 12 and 14. I was thinking about how to hook up a stereo source to two mono integrateds. I'm thinking about bidding on these too. I see those Eico pre-amps going for reasonable pretty often, this could make a decent deal. The 81's are too expensive when they are on ebay, and I don't have time to comb pawn shops and thrift stores for the stuff. jazman, "So, the HF-81 is not a religion or mystical object to me. I am willing to ask questions and pursue answers, and if it's just all parts, let's charge by the screwdriver twist to price the damn thing and make some bucks. We'll just attach mystical attributes to it based on the number of screwdriver twists in the marketing plan. Has anybody got anything against pursuit of more information and the possibility of making a little money?" Exactly. I'm real good at figuring out how to build stuff and then productionize that process. Probably has to do with my years working as a human robot in the plywood mills. Kelly, mdeneen et al might well be right about the amp being more than the sum of it's parts and stuff like that is always cool. That in no way excludes something else from being more than the sum of it's parts too. OTOH, it might also be a very well matched combination of tubes and trannies that could be duplicated if somebody took the time to analyze the stuff and dig up the needed parts. They were selling this deal for $70, the stuff in it couldn't have gold plated for that money. And, back to my earlier question, who can analyze a transformer? Tom Quote Link to comment Share on other sites More sharing options...
AndyKubicki Posted September 1, 2002 Share Posted September 1, 2002 This is an interesting proposition, to essentially re-issue the 81. Has anyone been able to compare the Marantz re-issue of their 8B (I think that was the re-issued model, not sure)? Perhaps it would be worthy to note how the re-issue varied from the original in terms of parts as well as sound. Were there any Mac re-issues? ------------------ Andy 78 Khorns (20' apart!) Audire Difet 3 Preamp Adcom GFA 535 II NAD 4130 Tuner Marantz CD 63SE Pioneer DV 434s>c> Quote Link to comment Share on other sites More sharing options...
NOSValves Posted September 1, 2002 Share Posted September 1, 2002 Those HF-14s are going to rise to over $400 or more I would bet. I've been watching ebay for a nice set of mono blocks of any brand and pairs alway's end up in the &400 to $500 range and allot get near and above a $1000 . So I hate to burst your bubbles and really wish you both all the luck but .... Its to good to come true. Craig This message has been edited by NOS440 on 09-01-2002 at 03:29 PM Quote Link to comment Share on other sites More sharing options...
mike stehr Posted September 1, 2002 Share Posted September 1, 2002 Oh well, So goes it on Fleabay. I couldn't afford more than 30 bucks anyway! I've been eyeing these old pair of Pioneer CS-06a omnidirectional speakers at the thrift store on base where I work. They were 50, now they are 30 bucks. They probably won't sound like nuthin' special, but they are interesting from a vintage point of veiw. And they are in wonderful shape! They might do well on my Eico junk, if not I can always Fleabay them for my cash back. And they'll still be 30 bucks when I roll in there Tuesday! Quote Link to comment Share on other sites More sharing options...
mike stehr Posted September 2, 2002 Share Posted September 2, 2002 Here ya go, Another thrift store find, a '64 Magnavox AM/FM phono console for 4 bucks! The power amp is a single ended 6BQ5 with 6CA4 rectifier and 6EU7 driver. Sans output tubes and rectifier, with 6EU7 parked in the 6CA4 spot. (I hope they didn't fire it up with the 6EU7 in that spot.) The AM/FM phono section is a seperate unit, so the tone/volume controls and phono input are contained within this unit. So the power amp is a straight up power amp, with just two rca inputs for left and right. It's teeny, chassis measures about 8 1/2'X 5'. Output trannies are micro size. Speakers are original magnavox units, and in good shape. Typical run of the mill era ceramic caps, carbon comps, and those black Sprague coupling caps, which more than likely leak. Even though this is factory wired, it still looks like a mess to me. And it is safe to assume that the multisectional is bad, especially when it has a red felt pen marker line on the top of it. Nonetheless, it's a real simple circuit and won't cost much to replace a few parts. The multisectional would be the most costly. Could be a good tweeter amp! Man, 6BQ5 burnout. This message has been edited by mike stehr on 09-02-2002 at 12:45 AM Quote Link to comment Share on other sites More sharing options...
NOSValves Posted September 2, 2002 Share Posted September 2, 2002 Mike, Actually this could be a sweet little amp what all do you have for test equipment ? The 6EU7 is a low noise version of a 12AX7 it uses a different pin out so there not interchangable. I have a Heathkit that uses the 6EU7. It has a power cord wired directly to it ? Most of these amps have to have a switch soldered in to turn them on and off or hard wire them so there on when power is applied to the amp. Craig Quote Link to comment Share on other sites More sharing options...
mike stehr Posted September 2, 2002 Share Posted September 2, 2002 Craig, Not much in the way of test equipment, just a Fluke 8050a tabletop. Yeah, I need a variac, a signal generator, and eventually a scope. But what I really need is a tube tester. (Like everyone and their dog.) Yes, the 6EU7 is the 6 volt version of 12AX7, no swappin' there! Pardon me, but I am a little confused about the last bit of your post, but your saying a 6EU7 that is directly wired to line voltage? It's not behind a power trannie or rectifier tube or rectifier bridge of some sort? You threw me. I tend to agree with MD, that these old EICO HF-81's have their own kind of sonic signature from being 40 years old, like the Fender amps he references to. Most guitar players would never rip apart a good working vintage Bassman just to reverse engineer and try to improve the design. So when you start doing major POOGE with the Eico 81, the 'Sonic signature' whatever in the hell that may be, could be forever lost. (I think this theory has already been posted.) The Eico transformers? who knows!!?? They sure run hot, that's one thing they have in common! This message has been edited by mike stehr on 09-02-2002 at 12:20 PM Quote Link to comment Share on other sites More sharing options...
NOSValves Posted September 2, 2002 Share Posted September 2, 2002 Mike, I guess I ran those 2 sentences together and thru you for your loop . I meant to say does the amp have its own power cord or does it rely on the preamp to turn it on and off ? Craig Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted September 2, 2002 Share Posted September 2, 2002 The 30 second rule is far too conservative if talking power transformers. There are many power transformers designed to run hotter than this. Some of the EICO mains iron is rated to run continuous at 225F with 195F not uncommon and even expected. Put your hand on a McIntosh transformer and you can leave it there for six weeks, this, as you know, is due to their design. Meanwhile, there are many amps that run the transformers FAR hotter than this, especially after cranking the beast for a few hours at full volume (discounting the fact that the more you run in class A, the more the unit is fully powered up anyway with no switching). I am not sure if you are talking output iron - the outputs on the EICOs run much less heat than the mains. And the output NEAR the mains get much hotter for obvious reasons. But a very hot transformer does not aways mean a problem and 30 seconds is NOT doable on the average HF-81. Indeed, my better sounding unit is hotter than my second best! kh Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted September 2, 2002 Share Posted September 2, 2002 Well, if talking the outputs, I have found the EICOs dont run too hotter than normal, except for that right output nearer the mains. Most people, when talking about hot to touch trans, are talking about the mains as the outputs dont usually run HOT hot, even on total Class A circuits. So yeah, if it's the outputs, 30 seconds is doable. 225F is the DESIGN rating but the power trans is supposed to run below 195F. But to be able to run at 225F without strain is good. kh ps- Congratulations on the amp Quote Link to comment Share on other sites More sharing options...
mike stehr Posted September 2, 2002 Share Posted September 2, 2002 Sorry I didn't clarify which transformer. I thinking more in the way of power transformers. My RCA SE amp, and my Bell PA amp power transformers run about as hot as the Eico's, the Eico's have been reliable, and the output trannies you could touch all day long. I'm currently using the little RCA (Not the Magnavox) SE amp with the original RCA speakers that came in the cabinet in a infinite baffle kind of setup. (That's what they were anyway.) In a smaller room it sounds nice. The 10 inch speakers are dual cones with a 3 or 4 inch cone tweeters. With mellow music it shines. I just put my hand on the bell caps on the POWER trannie of this SE RCA 6BQ5 amp, I can hold it there for 30 seconds. Now the part with the laminate plates will sting your fingers in about 3. The half built Eico HF-81 is at 160 bucks with 6 days left, Will Craig's geuss of $400 be correct? Craig, The little Magnavox SE amp has the power cord going to the power amp with power trannie and rectifier. The pre-amp tuner section is powered from the amp itself, with a plug. So the amp with work without the pre. And the amp has a left and right rca input itself. I like that option. This message has been edited by mike stehr on 09-02-2002 at 03:18 PM Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted September 2, 2002 Share Posted September 2, 2002 Anybody got a bum or suspect Eico transformer? Or even a reasonably priced good one? rusty wouldn't matter. Tom Quote Link to comment Share on other sites More sharing options...
Chris Robinson Posted September 2, 2002 Share Posted September 2, 2002 Forgive me for being absent of late ... but I've had a moment to hit the Forum and this was my first thread ... and what a thread! I'm not an engineer, and I didn't sleep in a Holiday Inn Express last night, so this is real ignorance posting ... I would LOVE to pay an obscene amount of money to take that kit for sale on Ebay and just put it in my Safe Deposit Box with instructions like, "Do not open until 2050" ... because I agree that this is a perfectly preserved museum piece. These are rare and should not be subordinated to assembly; we have plenty of those. My only comment is that "yes, it has questionable tone controls, balance controls, and an intermittent 'power on' light", but the unit just beats the piss out of other amps I've attached to my Khorns, regardless of price. Yes, it could be the irresistable love of its eclectic beauty, it could be the all-Mullard tubes, or the lovely brass plate, but Jeez, it sounds great. It sounds like M-U-S-I-C ... it makes you tap your feet, makes you get goosebumps, your fur stand up, my wife wants sex ... all kinds of good stuff. All in a little box ... I will NEVER sell this amp. Period. So what's $750 for this museum piece? I blew as much money on the SuperAmp which was a GREAT amp --- ask Dean ... but it just wasn't for me. So when we figure this out, and someone designs a stripped down HF-81 modern version, let's not forget to put the nice brass plate on the front so we can see MH in his really cool Scottish shorts ------------------ "Bullsh*t!" -PWK- --------------------- TWO-CHANNEL SYSTEM Eico HF-81 Eico HFT-90 New Tube 4000 CD Player 1976 Klipschorns (KCBR's & ALK'ed) HOME THEATER Klipsch 1968 ALK Cornwall "II"s (LF/RF) ALK Belle Klipsch (Center) Klipsch Heresy (RR/LR) Klipsch KSW-12 sub Sonic Frontiers Anthem AMP1 (driving Cornwalls) Sonic Frontiers Anthem AMP1 (driving Heresy's) Denon AVR-4800 Toshiba SD-3109 DVD Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted September 2, 2002 Share Posted September 2, 2002 Ole Chris is one of the lucky ones that managed to find an HF-81 gone over by a DIY freak. He paid a bit extra for these benefits as well as some good valves but as you can see, it was worth it. He dumped a $1200 Super Amp with NOS Mullards and RCA on Audiogon in favor of the lowly HF-81. In the past, Chris has had a few McIntosh tube amps as well, which he felt were bettered by the lowly EICO. No, the little amp is not magic, but damn if it does not sound FAR better than it has a right to. BTW, Chris.... if I dont get that stuff in the mail in the next two days, I will personally throw myself of my porch....and into the 6-10 foot waves coming in from that damn storm (surfboard in hand, however..heh). kh ps-Holy ----, I have those damn shorts on right now! That's embarrassing! This message has been edited by mobile homeless on 09-02-2002 at 11:54 PM Quote Link to comment Share on other sites More sharing options...
Clipped and Shorn Posted September 3, 2002 Share Posted September 3, 2002 The first transmitter I ever built did indeed have line voltage going directly to the tube filaments, and that tube was called a 117N7GT. And now you know the rest of the story. {back in those days, AC line voltage was 117 volts......or is that my age....I forget..... -C&s ------------------ Cornwalls currently upgrading to all tube components Quote Link to comment Share on other sites More sharing options...
Radiohead Posted September 3, 2002 Share Posted September 3, 2002 $261.00 with 5 days left. Sickly displayed. I thought I was the only one who knew about this. ------------------ Eico HF-81 1975 Walnut Klipschorns This message has been edited by Radiohead on 09-03-2002 at 06:49 PM Quote Link to comment Share on other sites More sharing options...
Chris Robinson Posted September 3, 2002 Share Posted September 3, 2002 Jeez ... hell with the throwing yourself into the surfage ... just declare a HURRICANE PARTY (even if one isn't aroudn). Fact is, I don't know what a HP is but I bet it's fun if your place isn't getting bashed to bits. Seriously, like I said, I'm just a stupid guy with a 56 IQ, but I do know what sounds like music ... I've got about $6K worth of gear in the family room and $1500 in the living room ... The Khorn/HF-81 combo is tough to beat. And having been born is '55, there's something really nice about having a 1959 amp driving those 'frigerators ... After all, my first amp was my dad's home-grown 5W monoblock (sweet!) so this kind of feels familiar. So MH, when's the 24' Hobie goin' out? Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted September 3, 2002 Share Posted September 3, 2002 I have just decided I am sending you the check via the mail tomorrow....waiting for me to pack those wacky top heater tubes is what has held me up like a loon. Those things could be sculpture! I wish my computer was back together. My digital card reader is out as is my scanner. I want to post a pic of your lovely valves....the BEASTS! kh Quote Link to comment Share on other sites More sharing options...
Clipped and Shorn Posted September 4, 2002 Share Posted September 4, 2002 kh speaking of C&S: "No hard feelings here... but reading these musings from someone that has neither particularly good ears or an understanding of engineering in relation to the subject at hand is not easy." None taken. My far superior comprehension of the soul of the music itself more than makes up for my perceived "deafness". I spent way more time in jazz clubs and concerts than snooty hi-fi shops discussing "virgin blackness", "rhythm", "pacing" and "grain". -C&S ------------------ Cornwalls currently upgrading to all tube components This message has been edited by Clipped and Shorn on 09-04-2002 at 01:59 AM Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.