Tom Mobley

Maybe he's using an old Hammond organ for a preamp?

The German plans I have, called Isophon, have wrong dimensions for the front upper piece that mounts the squawker and tweeter. The large opening for the K400/401 is too low, there's no room for the bottom mounting flange of the horn. The tweeter opening also needs adjustment as a result of moving the squawker opening up 3/4 or 7/8". The bottom 3/4" of the front piece is blocked by the roof of the doghouse. If I had it to do over I wouldn't cut those holes till there was an opportunity for a trial fit. Tom

I'll guarantee that .700 will produce a large pile of Krell-dust. I fired a bad-boy piece like that once, it's like being near an artillery piece when it goes off. Yikes. Same guy had a single-shot handgun in .308 Winchester. Ouch. Tom

those look more like K77V, alnico magnets. I believe it is the K77M's that have the square ceramic magnet. I've been under the impression that the K77V round alnico magnet are the "preferred." The K77V in my 77 Heresy's are all black on the horn part, the magnet cover is plain metal colored and has more rounded look at the back edge. That bluish-gray color is the exact shade my K55V's are painted. Why not play them, see how they sound? That's what really counts. You could put one im one speaker and A/B them your hearts' content. Tom

well good. turns out I bought from "lowtechelec@speakeasy.org". I did the BIN thing since I got tired of waiting for something to come along. One pair was like this for $77: This matched pair of ribbed plate Telefunken 12AX7 / ECC83 preamp tubes was tested on my newly-recalibrated Hickok 600A for shorts, gas, and transconductance. There were no shorts or gas. Transconductance was 1190/1240 for Tube One and 1250/1300 for Tube Two (new/nominal is 1250 -- a match within approximately 5%). And, of course, they have the Telefunken <> in their bases. I have played them throughout the day in my Dynaco PAS3 Version II; they sound excellent and are dead quiet when the preamp is muted. the other was these for $55: This matched pair of smooth plate Telefunken 12AX7 / ECC83 preamp tubes was tested on my newly-recalibrated Hickok 600A for shorts, gas, and transconductance. There were no shorts or gas. Transconductance was 1250/1125 for Tube One and 1100/1220 for Tube Two (new/nominal is 1250). This is nearly a perfect match when used in series-gain circuits and is OK for phase splitting as well. Naturally, they have the Telefunken <> in their bases. I have played them throughout the day in my Dynaco PAS3 Version II; they sound excellent and are dead quiet when the preamp is muted. so far so good, the 81 sounds great, but I'm still having issues with balance or one side is just stronger than the other. Tom

C&S, can you post that ebayers name or handle? Do your fakes have the <> diamond mark in the center bottom? I'm concerned about a couple I got too. Mine were not represented as NOS, tho', just good used with big tube tester numbers. Tom

I can live with it now that they've got the "jump to" box at the bottom of the screens. not having that really bugged me. Tom

Craig, sorry, spaced out your req on the Sam's. Email me your PO address, I will make some copies and send. tmoble@earthlink.net Tom

Hey guys, I really appreciate all the info and in-depth knowledge bring provided here. I's like to post some results but I've been working 12.5 hr days this last week and I'm taking my son up to see Thomas the Tank Engine (those w/kids will know) and it/he is at Williams, Az near the Grand Canyon. So, I haven't been able to work on it in several days and won't be able to today either. However, I'm looking forward to fixing these grounding issues and reporting results. In other words, real life intrudes. Kelly, I do have it plugged into a power strip, albeit a quality one. Also, on the same circuit and not far away from a dual tube 4ft. flouescent light over the bench in my garage, I'm wondering if it's feeding hash into the circuit ala' Roger Stevens battery charger. I'll look at that volume control deal too. I'll try to see some pics, but the long stem deal makes me wonder. There's already a cut-out in the chassis for the vol pot. Basically, my goal here is to get the thing sharped up and playing well with resaonably priced available components so I can have somebody with real ears evaluate it and start making some prelimninary decisions about the feasibility of reproducing it in some fashion. The part that worries me is the PS/trannies and that that multi-ganged function switch. Along the line several decisions, some marketing based, will need to made about reproducing the appearance, the functionality or both. It sort of appears that the circuitry could be simplified greatly by eliminating the tone controls and all the sort of oddball functions no longer used. But then, what about the knobs that control that stuff? This could impact the final appearance greatly. Lots of things to consider here. Later, Tom

Huh?? 2.5 YEARS? Did I miss something here? Seems like they should have returned your money about 2.25 years ago? What's up with that? Are they still in business? I don't get it.... Tom

Pat, Thanks for clarifying that about the can cap. I was wondering what it actually was, basically just 3 big caps stacked up. I'm at work now till 7:30pm MST tonight, but I'll look at the underchassis space to see if there's room for the upgrade. It's kinda tight under there, and that 40 would be the same size as the 40's I already put in. Would those disc caps on the multi-ganged function switch be considered to be "in the signal path"? Tom Jeez, I started this about 9:00am MST, just got it sent now. been a little busy today....Sheesh. What happened to my nice quiet Saturdays with an OC-6 net connection?

yeah, those little .025uf ceramic disk caps on the bottom of the tubes, sort of peach colored? there's six of them, I've got new Auricaps for those but just haven't had time to put them in yet. Turns out that AES place is not too far from where I live, about 20 miles across town, I picked them up there the other day. They printed out the Sam's photofact deal for me too. It's pretty nice, gives a parts list, schematic similar to the one Kelly posted, ident's all the caps and resistors on photos of the chassis top and bottom. five big legal size pages altogether. good for de-mystifying the whole thing. that can cap shows as a 20-40-40, think I'll look around for one. Pat, Craig, Kelly et al, thanks for taking time to respond. Tom

Thanks Kelly, for taking time to respond to this. I'm figuring it's a ground issue also. on the bottom of the chassis there are a couple of solder lugs, look like copper eyelet crimp terminals, attached with bolt and nut to the chassis, couple ground wires attached to each. soldered, not crimped, I think I'll pull these, clean them, add a starlock washer between the lug and the chassis to ensure good contact. On another front, it had a brand new power cord attached when it showed up. This is a two conductor cord, no ground. Typical hardware store item, has a polarized plug. What does current conventional wisdom recommend here? install three wire cord, attach ground conductor to chassis? Also, I've discovered there's a another one of those black Pyramid caps on the power lead where it comes off the convenience outlet. Looks like it's connected from hot lead to ground. it's buried, can't read the value of it but it's physically smaller than the .1mfds on the tubes. Schematic shows a cap there, looks like it's labeled as a .03, does that make sense? Could it be the problem? any ideas/suggestions welcomed. Tom

Well, I've replaced the rectifier tubes with NOS Sylvania EZ81's, the 12AU7's with NOS Mullard CV4003 12AU7 ECC82, the 12AX7's with a real decent set of Telefunken, not NOS but excellent, and the EL84's with a real nice set of NOS Raytheon's. The stock Pyramid 30mfd PS caps went out for a set of 40mfd Spraugue Atoms. there is a hum that starts as soon as powered up, both sides, unaffected by adjustment of any knob or the hum pot. This hum hasn't changed since the first day I had it with the bad EZ81's. Any bright ideas? It's really drowned out by any music at all, but it bugs me. Also, sometimes I feel the PS (I think) humming and/or vibrating. I thought this would be fixed by the new EZ81 or the Sprague's, but noooooooo. It did start running cooler when I replaced the stock caps and for some reason the whole amp seemed to run a bunch cooler after the Tele 12AX7's were installed. They came in last. I've not hardly had the volume knob up to 2, so I don't think it's a "hard to drive speakers at high volume" type deal. Aside from that and a tendency to drop out channel 1 at very low volumes this thing is just terrific on my DIY LS's. Absolutely kicks ***. (my asterisks ) Tom

C&S taken your meds today? maybe it's just default settings in a new piece of software. You're bringing new meaning to the term "majoring in the minors" give'm a break, it takes substantial time and effort to tweak a major software package. Try installing Oracle or Peoplesoft in an enterprise environment and making everybody's paycheck late. This is a hobby site. Tom

So, what did he do? Run over it with a monster truck? That tweeter looks like a alnico T-35 aka K-77-V to me. But I could be wrong. That Atlas number looks right too, but is it supposed to be 16 ohm? Tom

Nah, it's the images that are parked on the forum servers that will get wiped. All your gorgeous pics are just pointers to stuff on your own boxes, right? IIRC, the space for user images was really restricted, maybe that will improve. Tom

Mike, I'm in the same boat with my Eico. These people use terms like mmf, pf, .047uf. I'm shopping for parts trying to re-cap it and it seems I'm always thinking there's a Zero missing somewhere. Or a decimal point fell off somewhere. Probably just me, I guess. A micro-micro is a millionth of a millionth, looks to me like. Seems to me like the industry is using that term to refer to the quantity I would call a "milli-micro", a thousandth of a millionth. Picky, picky. Tom

Well, I dunno, I see: Buy It Now for US $34.00 each If I had interpreted that as $17 each I would already have them. As it was I bought this deal from a guy in Missouri, same thing I think: LOOK! NOS Mtch Pr Mullard CV4003 12AU7 ECC82 Item # 1383376499 http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1383376499&ed=1032843180&ssPageName=ADME:B:EOA:US:2 He gives lots of info, including test results. Tom (who borrowed a Eico 635 tube tester today and discovered that one of his EZ81/6CA4 won't pass the grid leakage test, turns on the warning light as soon as it comes up. wonder if that's got anything to do with that hum...)

Craig, see http://www.audiotubes.com/12au7.htm also, along the same line is http://www.audiotubes.com/12ax7.htm 12au7 from $8 apiece to $200/pair, lots to choose from. guy seems pretty straight up to me. Lots of good info on the tube there also. Tom did you see my question about the .22--.33 cap deal? appreciate any input.

Jim, >>My wife is threating me with a trip to Dallas to see the kin. Not sure if I am up to it. hehehe, is that short for threatening or long for treating? Tom

At AES they have the Auricaps in either .22uf @ 450V or .33uf @ 450V. which of these would be better in the HF-81 ? Original is .25uf 2 200V. I believe these are in the phono pre-amp section, attached to the 12Ax7's on the left of the chassis. How does this work? there's four 12AX7's, looks like two of them are the phono pre-amp and the others are tied in with the 12AU7's. Is there separate pre-amps for the phono and then the AUX, tape and tuner? I've got the 40uf Sprague Atoms, a nice NOS pair of Sylvania 6CA4/EZ81's for the rectifiers, a nice matched quad of of NOS Ratheons EL84's all coming in this week. I need to order the rest of the caps now if this stuff is going to be available during my next string of off days. I'm ordering the four .1 @ 400V Auricaps from AES, I'd like to get the .22 or .33 in with that order. Any help appreciated here. Tom This message has been edited by Tom Mobley on 09-23-2002 at 11:07 PM

Craig, I looked at those too. dunno. do know it would be a PITA to send them back to UK. checked at Brent Jessee at all? http://www.audiotubes.com/ seems pretty cool to me. He was willing to spend a little time on the phone with me, help me understand some stuff about caps and tubes. Tom

djk, Now that is interesting. If that's what he believed I wonder why he built all those speakers with a 3 x 13 slot? Got any bright ideas on this? Doesn't seem to add up very well. I dithered about this quite a bit when I got my DIY LS's together, almost bought a set of 4 ohm JBL and opened the slot up to 6". In the end nobody could come up with any definitive answer on whether or not the speakers would actually sound better that way, although I can't imagine why not. I bought a new set of K33E's and put them together. Now here is the kicker, I've discovered that the guy who originally built the boxes left out the "mosquito wings", the angled slats between the motorboard and the back that form the first portion of the horn. I'm going to pull the backs off and put them in. While they're apart would you recommend enlarging the slot to 6"? I'm hinky about this deal. If it matters, most of the listening to these speakers is at very low volume compared to what a lot of people do. BTW, I saw your mod sealing up the top of the cabinet and cutting through to the woofer chamber, that's an interesting deal and quite do-able. I just need to spend the necessary time to understand the electrical part of the mod. Tom

dean, go to Al's site http://www.alkeng.com/klipsch.html and look at the pictures of his crossovers. You'll see some little posts that act as sort of junction boxes, you can wrap several conductors around and solder. Also provides a stable spot for things to meet. I've got some extras from the AlK crossovers I built.... Tom