Thoriated_Tiger

PSB: Nothing new there. Horns have long been maligned by 'audiophiles' -- envy, I guess, since the only thing that even comes close to a proper horn, to my ears, is a nice planar or stat. Cones / domes just don't cut it. PWK's straight-forwardness didn't help either. I bet he made many, many enemies in the audiophool press and industry. Screw 'em. We know better. ;o) Since the advent of the avantgarde, which is oh-so-pretty and expen$ive, I've noticed an uptick in interest in proper, compression-driven horns. (vs horn-loaded lowthers.) Perhaps this time around, our horns will triumph... Naah. People are still too gullible. We'll remain a fringe, and personally, I'm proud of fringe ;o)

The DG/Archiv box set of Mozart's Symphonies (Pinnock) The DG/Archiv box set of Beethoven's Symphonies (Gardiner) (#8 is becoming a new fave of mine) Mahoromatic soundtracks (all 3 of 'em, Toshio Masuda is the composer. Anime.) Squirrel Nut Zippers "Christmas Caravan"

---------------- On 11/1/2004 10:25:58 AM CaptnBob wrote: Something to remember if you are putting this on a test bench - the channels do not have a common ground on the early ARC amps. The 4 ohm taps are common. Just thought I'd throw that in to add to the confusion. ---------------- Noticed that in the D-76A runes.. dunno if the 70's the same way.. probably is.

Just exploring, folks.. thanks for the replies. As for 'sports car' personality -- I drive sports cars, and I am my own tech ;o) Ditto for tubes. If I can't wrench on it, I don't want it. I've been a fan of Audio Research since I was a little kid. This one's not about sonics, per se.. this one's one of those things I have to do for myself. That ARC has good sonics is a bonus. =o) I'm heavily pondering a D-70 MkII, and pretty much will gun for only that one at this point. 60 wpc, runs the 6550's on the conservative side, so current-production glass should have no issues with it. I'll get around to building my own.. for now, tho, I think I really do want that shiny one with the black (deep, deep anodized purple, actually) handles. Everytime I look at my SP6A I smile, because I remember when they were new, I was about 8, and had no hope of ever having one.. so what's this one doing here.. hmm... =o) The current stuff is so stratospherically priced I'll have to wait another couple of decades to afford something like a Ref II Mk II preamp ;o) Perhaps some forum members would like to go over the runes for the D-76 with me? (I can't find 'em for the 70 I want..) There's voodoo in there I don't grok. WTF is a 'cross-coupler?' The feedback stage seems to loop from the output tranny to a 12AX7 (!) then on into the input ckt.. is WZJ known to be a weirdo? ;o) D-76A runes (it's not the D-70, but close, from what I hear): http://www.arcdb.ws/D76/ARC_D76A_schematic.JPG

Anyone firing their Klipsches with Audio Research moderate power tube amps? Say a D-76 or a D-70 or similar? How is it?

My ARC SP6A has no tone controls. It has a Balance control which remains centered (I do work it when I remember, a few times, just to keep it clean.) I don't miss tone controls. Not since getting the Fortes. Before that, I *desperately* wished the ARC had a Loudness function.. but not anymore. (Had SF2 prior to the Fortes.) Instead, I found that some recordings (mostly DG / DG Archiv) would sound overly bright/harsh when the orchestras were going tutti (mainly in their 4D 'DDDD' recordings.) It was SCR / Solen MKPs in my preamp's signal path. A 'mod' by previous owner which I have been rectifiying in the past 2 weeks. I swear those MKPs lend a cheap solid-state sound to the whole rig. No tone control coulda fixed it, because besides harsh/bright, the very leading edge of a crescendo would 'crackle' almost imperceptively. Similarly, no speaker wire or patchcord coulda fixed it. Mask it, yes, change it somewhat yes, but not eliminate it.

Actually I was thinking of reterminating the aq wire -- I wanted to take a step above radioshack and monster. Instead, I filed one side of each barrel flat. It's soft brass, a bastard flat file did short work of it. Looks neat, even. All I had to remove was about .5mm from each barrel, now it fits comfortably. So far I like what I hear.

The announcement earlier here about AA selling these off prodded me to get two pair. I was half-expecting the pretty RCAs *not* fit my amp.. and i was right. It could be forced, but it's not nice to force a 40-something year old machine into anything.. Queried AQ (jeez, they have to have *the* fastest email response i've ever seen!).. they won't reterminate, no 'narrow-barrels' for them. So.. Vampire? El-Cheapo RatShack? What'd fit this amp's very tightly-spaced inputs?

Do it, fini. I'm curious about the 500, I want one for my office. It can't possibly be *any* worse than an HK TX-7000 I had. That thing..ugh. Double-ugh. No turret boards, everythign point to point, in layers. One big honkin' ground bus spanning the chassis. I'm hoping the 500 is cleaner in design and layout. Like others have hinted, a receiver is tougher to work on than an amp. But it's not that tough, imo it's much easier than trying to replace microscopic compontents on a hi-density double-sided pcb. ;o) It's probably a bad filter cap(s) somwhere. Hmmmmmmmmmm..yeah. Could be something as sinister as a pair of wires that are supposed to be twisted (for RF rejection) and for some reason they're not.. could be a bad solder joint on a ground, etc etc.. now we're talking doing hot voltage checks and hot pokes with wood *WOOD*!! chopsticks. Techniques which must be learned if one is to work on this stuff. This stuff can kill. Quite literally. But it also can be tamed. Hot voltage checks still give me the a little bit of the willies, but I follow common sense and established precautions, and I'm still here ;o)

Yeah, just like my car. Mostly stock, except... but it still has the stock block and head. Still has the stock gearbox and rear end. Has better brakes. Better springs/shocks. Otherwise, still fairly stock. My dyna's much the same. Same original ckt, same iron, same chassis, same wiring even.. different sockets, and a bit of a boost in the power supply. But still recognizable as a 70, physically and electrically.

Yeah, I know. But at least it's not a bastardized hack, and still uses the original ckt. The bass came back bigtime with a fresh can cap, but a little problem remained -- when running near full throttle, the most extreme low end would flutter. (Flutter is the best i can come up with.) Funny thing is, after I did all that I ran across a review from High Fidelity, 1959, where they graph the same exact thing -- at full throttle, from 20 to about 30hz it dips. It was indeed very thin on the psu from Day One. Mind you, that's at 35 watts. Then again, I was testing into really in-efficient speakers, on purpose, to see the limits. The cap upgrade removed that flutter. If you full-throttle a 70 into Klipsches, you'll likely get blown into the back wall.. It just irks me that so many folks (it's not bad here, but in AA it's way bad) think the 70's bass-light.. it ain't. That can cap goes flat a lot faster than whatever McIntosh and other builders of higher-priced gear used. That flat can-cap is what gives it its tired, flat, flabby, thuddy sound... once it's replaced, the amp is no longer a warm, cuddly, gentle amp -- it has fangs. I wrote a review on AA about the 70 after restoration to enlighten those who parrot other's opinions / experiences without actually restoring one themselves. The board I use keeps the section just after the 5AR4 near-stock (60uf, I think? Maybe even 30) but just about triples everything after the choke. The diff between a flat can and a new can was night-and-day. The diff between the new can-cap and the sds board was oh so much subtler.. but appreciated.

With all due respect, Klipschfoot, I beg to differ. The 70 when brought back to specs has a bottomless pit for bass. Fast, bouncy, deep, well-controlled, well-defined bass. Just brought back to specs, mind you, not modified beyond recognition. Care to venture a guess as to why a 40 year old stock, un-restored 70 has no bass? By your logic, then a MkII should have flat, dull bass, and so should a McIntosh MC30, and even a Fisher 500. After all, *ALL* speakers of the era were bass-deficient, right? Someone forgot to tell PWK that, someone forgot to tell JB Lansing that.

Which brings up another point i've been thinking about regarding this thread.. the 70 would make a good solid learing vehicle, but as you mention, the prices are getting silly. Not as silly as other vintage iron, but getting there. =o( Fini, you may best be served, if you wish to learn, to sink dosh into a new kit. Getting and restoring a 70 or a pair of Mk whatevers is gonna get close to a grand. (Amp plus parts and tubes, if you need tools / equipment it gets worse.) May jsut as well get a bottlehead Paramour 2A3 kit and put it together.. excellent intro to the world of slinging solder. =o) If you really want a no-futz amp.. get one allready done from input to output by a reputable tech, but that won't be cheap. Or buy new, which is even more hideously expensive. The guy who runs n0rh has a single-ended EL34 integrated (8 watts per side) for 400. (no typo, and that's $USD). I'm so tempted to get one for the office.. instead of finding and restoring a Fisher 500. The solder-slinger in me cringes at the thought. The logical side says 'do it and be done with it.' I need a coin to flip..

I've tried ribbed telefunken, smooth telefunken (yummy), ei, sovtek. My favorite, even on top of the TFKs? JJ ECC83S. The one with the weird looking plate -- short and squat plates. It's a frame-grid, a pretty good copy of the Telefunken ECC803S. It has the telefunken liquid, airy, detailed, silvery sound. A real ECC803S can fetch four digits on ebay. This is *not* your grandfathers 12AX7. This is the one used in ultra-tweeky recording applications.. it just happens to make a killer preamp tube. Phono tube, too. Remarkably quiet. The JJs are 9 bucks a pop. My telefunkens are sleeping in their boxen, awaiting being juiced up once more -- but as long as JJ makes the ECC83S, they'll remain asleep. That's my 2¢...

No affiliation, although it *is* awfully temping for just the "WTF?!" factor.. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5724620772&ssPageName=ADME:B:SS:US:1 I grew up thinking muzak was an evil of the 60's and 70's, crappy little ss boxes feeding multiple speakers with brain-numbing 'music'.. I bet this thing pumped out 101 strings 24/7 for years.. paralyzing brains, and inducing thoughts of homicide.. ;o)

I guess it's all relative.. I've owned a couple of other vintage pieces, some good, some really nasty.. had an HK TX-7000 receiver, the filter caps were older than myself, yet they were still in great shape. The Dyna's was completely, utterly flat.. they weren't visibly leaking, and the piece didn't hummmm -- but it had *no* bass whatsoever. Got a 4-section cap from a guitar tech who had some, and it worked had bass back.. then the bias started giving me grief, which is when I went to the cap board. then there was a '56 GE TV where the filters were good, but every single paper cap was toast.. the filters in my Pioneer receivers (a 650 and a 680) are still good at 22 years.. The HK was the one that scared me. As far as I could tell they were the originals, datecode of '64, and were about the only caps I *didn't* change in that piece. That receiver also turned me off from tube receivers.. rat's nest doesn't even start to describe the guts.. please tell me a Fisher 500 is more neatly laid out (I want one for the office ;o) The Panasonics included with the board kit -- no idea how long they'll go for. I've had Dell motherboards with Taiwanese caps.. those caps blew and blew hard within the year. O.o

Cups of tea... I have a slightly skewed view of vintage iron. I like to keep it as close to original as possible. If I want a triode front end feeding into a pair of 34's per channel, I"d get an HF87 -- and I may, just to *collect* 'em and rotate 'em around. I'd also like a pair of McIntosh MC30s. And Marantz 8B. And this and that and that other.. I wouldn't modify my 70 beyond what it allready has -- because then it'd cease to be a Stereo 70, and would become a Curcio, or a Wellborne, or whoever designs the front end. By all means, a triode front end is cleaner, clearer, than the concertina we use. But it's not *that* much cleaner. Not to me, anyway. Not enough to say "I *HAVE* to ditch this amp, it sounds like crap." (I heared a Curcio top-dawg board, and yes, it was very very nice.. but somehow it didn't make me fork over the dough.) As for the caps? They didn't last all that long.. by 20, 30 years they're gone. The MKIII on the other hand fries 'em MUCH faster. Catastrophically, even, or so the stories say. Tridode Electronics has the original can cap, made by Mallory or on Mallory tooling (can't remember which..) New production, and relatively cheap. They also have the cans for PAS and a few others. I like my tea black, two lumps, no lemon. ;o) At this point in my progression in this madhouse hobby, I think I'm gonna build my own from now on. Vintage is fun, new is nice, but diy is from the heart. ;o)

One certainly doesn't *need* a board for the bias issue. However, with one stroke, these boards replace the entire can cap with something a wee bit stiffer, and removes that pesky selenium doohickey in one stroke. One could fashion something similar, by DIYing all of it. Sheldon Stokes has a PCB etching mask you can download for his board. www.quadesl.com . Or you could just line up a bunch of caps, silicon (hi-temp, please) 'em to the inside of the chassis, or any other number of options.. I liked the board because it was quick, simple, elegant. I've had this 70 for 4 years, it's been 2 years since the rebuild. I'm itching to build something new, but not because it sounds ill or something -- I wanna build for the sake of building. =o) I considered diving into another vintage piece, like an Eico HF87 or something similar. Instead, I'm gonna whip something out myself. Only way to learn. =o) My first will likely be a pushpull triode, my 2nd will likely be a pushpull EL34, both with all-triode front-ends. But I'll be honest.. nothing I've heared in these 4 years has made me want to ditch my 70 -- if anything, it's the reverse. After going to audio 'salons' and listening to friend's system, my little 70 / forte / arc combo makes me grin an insane grin -- cause their stuff don't sound like mine, even tho their stuff is 5x the price! (or more!) It's pretty sick when my reference is a very simple 1958 design! I saw the Rogue 88 into Tannoy Saturns, and I was thinking "Mine does better than this, on everything.. " I'll have to admit the Rogue is MUCH prettier than the Dyna, but sound-wise? I'll keep the dyna! Hmm.. come to fhink of it, none of those folk use K speakers.. maybe that's why.

A Stereo 70 driving K-Horns from an ARC SP3 is what made me fall for hi-fi and Klipsch in general.. a long, long time ago. It'll do just fine, but it does need a little attention. At a minimum: 1. Replace the can cap. Don't even consider not doing it. The can cap is highly stressed in this design, and goes flat real quick, leading to all the 'no bass' opinions. The 70 has a bottomless pit for bass, provided the power supply is good. You can a) use a new can cap, or use an under-board cap board. This is the route I chose for mine. Between the 5AR4 and the choke it is kept almost stock. After the choke, it triples what the stock design had. Triode Electronics has the cap board, it's a breeze to put together, bolts on standoffs under one of the output trannies. With that board, the 70 just flat out refuses to run out of steam and sounds cleaner at any volume. I used SDS the Labs (see www.triodeelectronics.com) board. It also gives the option of using the 5AR4 or a silicon rect. I kept the 5AR4, thank you. 2. Measure all resistors, replace those which are off. 3. Coupling Caps -- they used Pyramids... cheeeeep. Most likely leaky. Get four .1s of your favorite flavor and replace those old Pyramids. 4. RCA 7199's are a must -- GE and Sylvania also did well. The Sovtek 7199 is a sad, sad joke. This is the main selling point of boards -- "7199 are rare and scarce and expensive! Get our board, it uses other tubes and even makes coffee for you!" -- bah-loney. 7199's ain't cheap, yeh, but they last forever. I have hoarded a few for my own uses, they'll probably outlast *me*. 5. *BIG ONE* -- the selenium bias supply *has* to go. The SDS labs board mentioned in in #1 (and Curcio has one too) replace the entire bias ckt with diodes. Boards: I kept mine stock. But I did replace the actual board with one from Curcio Audio -- the PC3R, an exact clone of the original 7199 ckt, which I like. Concertina splitter and all. AFter that, it gets very wiggy. Everyone and their brother has a 70 board. The Triode Electronics board is very nice, it's basically the 7199 ckt but using EF86 as the pentode and a 12AU or AT 7 to do the splitting. This one is the closest to the original ckt, ditching the 7199 in favor of discretes. Curcio has an all-triode board. Welborne has another one, can't remember the details. I lvoe the sound of a freshened-up, stock 70. For preamp, the more neutral, the better. The Stereo 70 just loves a good preamp. Hook it up to a Dyna PAS and its mediocre. Hook it up to a nice modern design, and it just takes off like a rocket. Me? ARC SP6A. Scary how good a 1958 amp can be, when freshened up and brought back to 100% specs.

nice! 2A3 pp.. into kornerhorns.. you must be hearing something very similar to what pwk did. =o) I'm considering building a 2a3 of my own, dunno if i'm going to go pushpull or paralell yet. I'm even considering a single-ended EL34 in ultralinear

Here's mine. What warms up your listening room?

Never heared a Forte (I or II) be called bass-thin. If anything, they can be a handful in the wrong room =o) As far as amplification goes, I run my I's with a tube amp and tube preamp. In-room response is nearly flat with a nasty +10db bump at 50 hz -- that's the room. (assymetrical, one speaker is near a corner, the other isn't.) Bass guitar at high (realistic) levels rattle everything on the wall. Picture frames, etc. At more sane levels, even as low as 70-75db, kickdrums thump one in the chest. Pipe organ buzzes your innards. I'd call that sufficient bass ;o) Perfect ampli for the Forte? It has to be clean. And I mean *clean* at 1 watt. If that first watt is garbage, you'll *never* use the speakers. It has to be able to handle a 4-ohm load comfortably. 20-30 watts is enough for these speakers to drive 'em to triple-digit spls without clipping. There's no real reason to use a 100+ watt amp with these.

TT and cart can do wonders. I had a Technics SL1200 with stock arm and a Grado Black.. rice krispy city. Then I got my thorens 145 (the bearing on the 1200 is the diameter of a wood pencil, the bearing on the Thorens is the diameter of a cigar), with the same Grado.. it was cleaner. THen I put on the Audio-Technica AT440ML -- it's a microline stylus, rides deeper in the groove as opposed to an 'elliptical' -- below the surface noise. Things got a LOT quieter, good records barely have any noise at all. Then I got a Record Doctor II vacuum. Good records now sound almost like tape. Just the tape hiss, and the occasional tic. Bad records with the microline also pop differently. More like a scrape. *shrug*

Squirrel Nut Zippers "HOT." Wish I had this on vinyl.. it exists, but is so rare. =oP

I had my miata roll downhill once -- and it had the parking brake on. Glazed pads, I guess. Since then, I got meself into the habit of not only putting the parking brake on, but also putting the car in 1st gear. No more heart-stopping vanished-car moments for me now