find any KT-88's that were not Chinese except for the very expensive Richardsons. Sooo..I ordered some GE 6550's. These cost $60 each from Audio Glassic. The McIntosh manual says that the amp is designed to use either 6550's or KT-88's. I've been following Sam Tellig's series on tubes in Stereophile. He and others in Stereophile have been taking shots at the 6550's for some time now, downgrading equipment that uses these tubes and criticizing the tubes themselves as being "not audio tubes" and thus sounding inferior in general. Well, he's right, at least in his assessment of the 6550's in the MC-275. These tubes sounded grainy, coarse, and hard. There was a foreshortening of the soundstage and a more diffuse image. On the other hand, the power at audible clipping was now 94 watts per channel. The low end extension of the Richardson tubes was there but with slightly better control. I let them break in for about 50 hours, and I began to get used to them. One evening, however, I found myself shoving my speakers around the room and playing with the tweeter levels. This is a sure sign for me that something is not right with my system. On impulse, I plunked the Richardson 88's back in and the magic was restored. Now I'm back to square one. Does anyone know of a source of non-Chinese KT-88's that is not as pricey as Richardson? Does anyone know if there are basic differences in Chinese KT-88's or are they made in the same factory and just matched and graded differently by the various vendors (Gold Dragon, Gold Aero, ARS, etc.)? If indeed there are actual differences in the design and construction of Chinese 88's, does anyone have data regarding the electrical performance of these tubes, especially the heater to cathode breakdown voltage? UPDATE: Since I wrote the above, I have called McIntosh. An engineer there informed me that the MC-275 is NOT sensitive to tube matching. Given the relative youth of this amp, there should no problem with replacing only one tube! My listening tends to confirm this. There is absolutely no audible difference between channels until the clipping point is reached even with the cooked tube installed. I have decided to replace only the one tube. I can get an identical one from McIntosh for $150 (made by Richardson, but with the McIntosh logo on it). I am, however, still interested in the above questions. ------------------------------ Date: Wed, 9 Mar 1994 14:26:43 -0500 (EST) From: Ed Subject: EAD Optical cables I am currently using an EAD D7000 II processor and a T1000 transport. I am using a Siltech coaxial cable beteen the processor and transport but always wanted to try the ATT optical cable. Whereas I have heard big differences between different coaxial digital cables, I know nothing about AT&T optical cables. Does anyone have any recommendations or experience with different AT&T optical cables? Good Listening Ed Devlin ------------------------------ From: torgd@tolstoy.lerc.nasa.gov (Russell DeAnna) Subject: Re: Reply from HP at TAS (I'm just wild about Harry...) Date: 9 Mar 1994 19:39:13 GMT In article <2lkk2r$12ka@introl.introl.com> rogerk@netcom.com (Roger Knopf) writes: >Overall, I think he is much closer to discovering audio truth >than Archibald/Stereophile. I agree. Reading an issue of Stereophile feels like reading the daily news. It gets tossed aside, to be referred to if information is needed. Reading an issue of TAS is like completing an interesting book. Maybe I didn't hear about the latest rage in DCC, or MD, or Dolby Surround, but that information is textbook stuff---quickly forgotten. It's available for future reference. TAS explores the subtlties of the human factor in audio. Their prose is much finer than Stereophiles---save Corey Greenburg. **** TAS is to Stereophile as novel is to textbook. **** -- Russell DeAnna NASA Lewis Research Center, Cleveland, Ohio torgd@tolstoy.lerc.nasa.gov ------------------------------ From: jan@cobra.ansoft.com (Seaway Jan) Subject: non-Audiophile LP source? Date: Wed, 9 Mar 1994 19:53:15 GMT Does anyone have any information on LP mail order source for non-audiophile types? The LP store listed in S'phile or TAS are those audiophile types that only carry audiophile-approved LP and tends to be expensive. I would like to find some REAL music like Beastie Boys or Sly & the Family Stone. Thanks. Seaway ------------------------------ From: torgd@tolstoy.lerc.nasa.gov (Russell DeAnna) Subject: Re: Reply to HP Date: 9 Mar 1994 20:00:00 GMT In article <2ll3si$1eht@introl.introl.com> adamr@decon.Eng.Sun.COM writes: >Mass-market doesn't necessarily translate into lower-end (though >usually does of course). It would seem that over time, mass-market products lose their value. Consider movies, restaurants, automobiles, etc. Once everyone participates, the value offered to those who initially participated vanishes. Witness the status of LP records. It's a collectors game and a status symbol now. Collecting vinyl is like collecting art. -- Russell DeAnna NASA Lewis Research Center, Cleveland, Ohio torgd@tolstoy.lerc.nasa.gov ------------------------------ From: vandyke@cis.ohio-state.edu (brent vandyke) Subject: What should my next upgrade be? (opinions sought!) Date: 9 Mar 1994 15:04:21 -0500 My current (modest) system consists of an Adcom GTP-400 preamp, Adcom GFA-535II amp, Denon 1520 CD player, MIT T4 interconnects from the preamp to amp, Audioquest Topaz interconnects from CD to preamp, Audioquest speaker cable (not sure what type, 8 18-20 awg solid conductors) and Vandersteen 1B speakers. The problem is that there seems to be very little depth in the soundstage. I borrowed a Theta Pro Prime DAC and a Wonderlink digital interconnect from the local high-end store, Progressive Audio, and it seemed to help a little, but not NEARLY as much as I expected. Apparently, the CD player is not the weakest link in the system. I have tried moving the speakers around, and I am pretty sure that I have them in the best possible location. Progressive Audio suggested that I try a pair of MIT speakers cables, but I haven't done that yet. I should probably get rid of the Audioquest Topaz interconnects, also. I suppose the problem could simply be that I am expecting too much for the amount of money that I have spent. Anyway, I am looking for suggestions on ways to improve the depth of the soundstage (and imaging, though other than depth, the imaging seems to be decent) What amps should I try out? What preamps? Different speakers? Different cabling? I'm open to ANY suggestions. Thanks in advance! Brent VanDyke vandyke@cis.ohio-state.edu ------------------------------ From: torgd@tolstoy.lerc.nasa.gov (Russell DeAnna) Subject: Re: Reply from HP at TAS Date: 9 Mar 1994 20:24:26 GMT In article <2ll41n$1ehi@introl.introl.com> orth@everest.den.mmc.com (S.J. Orth) writes: :So, things that I input here might get passed along to THE HP. Wow! My :comments will also get read by others, whether Harry likes them enough to :print or not. TAS and TPV have their own e-mail addresses open for business. :I laughed so hard that I cried as I read about the on-going Tice Magic :Clock bullshit, with the "coherent electrons". For me, I figured that one :out. Maybe a magazine shouldn't print claims without technical merit. But readers must also use their brains to figure out whether or not this makes sense. If they can't or don't do that then caveat emptor. :What really did me in to TAS was HP's insult to people who live in or are :from the state of Kansas. Harry just sat through his sixty-third viewing of The Wizard of Oz. -- Russell DeAnna NASA Lewis Research Center, Cleveland, Ohio torgd@tolstoy.lerc.nasa.gov ------------------------------ Date: Wed, 9 Mar 1994 16:12:48 -0500 (EST) From: Ed Subject: Muddy Waters CD I also have just finished a listening session with the MFSL Muddy Waters CD and was impressed. Has anyone listened to any of the other MFSL releases that use the GAIN system and do they sound as good? Good Listening Ed Devlin ------------------------------ From: carver@freya.cs.umass.edu Subject: Re: Reply from HP at TAS Date: Wed, 9 Mar 1994 16:13:39 -0500 (EST) rogerk@netcom.com (Roger Knopf) writes: >Speaking as one who prefers TAS over Stereophile over every other >audio journal I've ever read, HP has his good points and his bad >points. >Overall, I think he is much closer to discovering audio truth >than Archibald/Stereophile. One the good side, his personal >standards for quality in audio reviewing and listening I feel >have given TAS much more credibility than Stereophile. On the >bad side, he can be extremely childish and immature when >contradicted, as evidenced by his recent contribution to this >... Speaking as one who prefers Stereophile to TAS--and who, in fact, just let his TAS subscription lapse (for good)--I must say that I strongly disagree with your relative assessment of the two mags. In part, this may be because I want something different from an audio magazine than what you appear to want. I am not looking for the magazine to direct me to "audio truth" as you put it--I will make such decisions on my own, thank you. What I want is for reviewers to give me some idea of how various pieces of equiment sound, to help me be more effective with my time. Why doesn't TAS fit this bill? In part, it is because they review so few things each year and especially so few things of interest to me. However, a major reason is their review style. Instead of telling us how something sounds, we have to wade through endless discussions of each writer's philosophy of audio design, or philosophy of "science" (though few of them appear to have even a vague clue what science is truly about), or philosophy of listening to music, or philosophy of...I guess you get the idea. You may like this style, but I find it *extremely* aggravating. (The only one that doesn't write this way is AHC, and we see how HP treats him.) As for editorial quality control...I guess you don't bother reading the digital-related articles--since they are filled with nonsense. For instance, that article about digital problems a year or so ago that was full of obvious errors. Of course, when these absolute, unrefutable errors were pointed out in letters, the response was that the letter writers "just didn't get it." Apparently what they just didn't get was that digital sucks, so who cares what gets said about why it sucks. While Stereophile is testing for jitter and publishing technical articles on it, TAS' writers are still talking about "transports losing the bits representing inner detail" and postulating unlikely models of human hearing to support their contentions that digital *can't ever* work. I see no evidence of editorial quality control here! As for backtracking on overly rave reviews...I see plenty of that in TAS. Just what are we seeing regarding the BEL amp? Turns out it may not be the breakthough of the decade after all. (At least the recent negative comments on it were not proceeded with the usual bowing and scraping to the "great HP"--as is the usual mode for contradictory reviews.) As for enlightening us about "audio truth"...a favorite recent example of HP's perspicacity [said with heavy sarcasm] was his comment in the context of his "state-of-the-art" amplifier series that was something like, "if you want to hear grey then listen to the Krell" (MDA-300?). How enlightening. Doesn't this also contradict the positive review previously given by AHC? [And no, I don't own this amp.] Add to all this the fact that my intelligence is insulted numerous times in every single issue of TAS ("anyone who reads Stereophile is stupid"). Who needs this for $50+/year? Some people say that this is just HP's "style" but I don't think that appearing rude, immature, conceited, and (increasingly) paranoid constitutes having "a style." Maybe HP really is as single-handedly responsible for "the high-end" as he and his staff seem to believe, but for me this doesn't excuse HP's and TAS' problems. (PS: Much of HP's writing is virtually unparsable and while his photos on the back cover are probably better than having ads, they are quite mediocre. What makes the photo quality so striking is the high regard he holds for the cover artwork. It seems strange that he wouldn't want to have quality artwork on the back as well--unless he believes his photos really are good.) Norman Carver Computer Science Department University of Massachusetts ------------------------------ From: aflgenes@aol.com (AFL GeneS) Subject: Re: tweek vs. science Date: 9 Mar 1994 16:11:22 -0500 <> This paragraph is based on an absolute misunderstanding of what scientific audio engineers mean by double-blind A/B/X testing. You are free, and in fact, requested, to listen to music in the same way you always listen. But because you don't know which component is which and the levels are precisely matched, differences based on volume level and the appearance of the product do not influence your decision. Under those circumstances, many of the differences you hear no longer exist. And when they do exist, there are often measurable reasons for that difference. You are not determining here whether the soundstage is better, or the highs are liquid or not. You are simply deciding if one component sounds different from the other. If a difference is thus discerned, then the combination of measurements and subjective listening may determine more. Peace, Gene Steinberg ------------------------------ Date: Wed, 9 Mar 1994 16:38:00 +0000 From: "henry (h.) pasternack" Subject: KT-88's and McIntosh MC-275. mks3433.cvc1@pcmail.dcccd.edu writes: >Sooo...I loaded the Chinese 88's back in. They sounded a bit >brighter with a fine powdery grain added, a broader but narrower >soundstage, and less output in the extreme low end. Broader but narrower? >I've been following Sam Tellig's series on tubes in Stereophile. >He and others in Stereophile have been taking shots at the >6550's for some time now, downgrading equipment that uses these >tubes and criticizing the tubes themselves as being "not audio >tubes" and thus sounding inferior in general. If you look at the Tung-Sol data sheets, it's clearly spelled out that the 6550 is an audio tube. I have an old article that says it was specifically designed to take advantage of the ultra- linear connection. See the February "Stereophile" where Manley defends the tube. Of course, a lot of his amps use 6550s, so I wouldn't expect him to say bad things about them. However, he does make the interesting claim that modern 6550s, not just the Chinese ones, sound like junk. He recommends the new Sovtek tubes. I asked Steve Angela about these and he said they're pretty good. No offense, but if you're spending $60 for GE 6550s, you're just throwing money down the toilet. It amazes me how these tube scam artists rip off unsuspecting audiophiles. You should be able to get a decent matched *pair* of GE 6550s for around $50. The Sovteks are about the same price, and better quality, I suppose. Question: Has anyone tried the new Sovtek EL34s? Enquiring minds NEED to know! -Henry ------------------------------ Date: Thu, 10 Mar 94 09:48:20 -0500 From: Scott Dorsey Subject: Output tubes The Chinese KT-88s are really bad.. they don't really meet the 6550 specifications, let alone the KT-88 specs, and when driven in an amplifier that has a fairly high plate current (like the Citation II), the lower plate dissipation tends to cause them to blow up in a very dramatic manner. The fact that they work at all in the MC-275 is a tribute to the very large design margins in that amp, and the fact that the amp is extremely conservative in design, so as to extend tube life in general. You can get a lot of non-Chinese KT-88s. Call Gold Aero and ask them what they've got in stock. These guys charge way too much money for tubes, but they really do guarantee what they sell, and if you don't like it, you can return it. They also sell the KT-99 which appears to be identical to the KT-90 (and you can see my review in Positive Feedback this upcoming issue). This is a good replacement for the KT-88 in many amplifiers... it has much better plate dissipation although you might want to tweak the screen bias somewhat. In the 275 it might be a good choice, indeed. The GE 6550s are pretty good, unless you get later tubes from the end of the production when they tended to be very careless about construction. I've had a lot of problems with late GE 6550s, but the earlier ones are fine. --scott ------------------------------ Date: Thu, 10 Mar 94 11:56:12 EST From: jas@proteon.com (John A. Shriver) Subject: Re: KT-88's and McIntosh MC-275 The McIntosh output circuit is an interesting environment for a power tube. The good thing is that it runs Class B. (Yup, just like 1960's transistor power amps.) This means that the plate dissipation at idle is nice and low, which is really easy on the tube. However, it is tough on tubes in other ways. First, the screen (#2) grids are running at the full plate B+, moreover with the full plate B+ swing. This can exceed the screen grid voltage rating rather easily. (The Radiotron Designer's Handbook really dings them on this point.) For instance, the Sylvania 6550 data sheet I have handy shows design center maximum plate voltage as 600V, and screen as 400V. (I'm sure the Tung-Sol is the same.) The second is that the cathodes are swinging, and that can (as noted) put some heater-cathode stress on. However, I suspect that the breakdown in the Chinese KT-88 tubes was probably screen (grid #2) to supressor (grid #3). I've seen sick EL34's arc this way on big voltage swings. It's also likely since if the supressor grid droops some (from heat from the plate), it will get darned close to the screen. Since the supressor is at the cathode voltage, there's a lot of potential difference. At any rate, when your tube went cherry red, the cathode (and plate) current was probably astronomical. The cathode probably fried it's oxide, and lost all the emission. That's why the low power output on that channel. I would not even consider using Chinese power tubes in such an expensive power amplifier. They are complete crap in my experience. They will very rapidly go gassy, since the Chinese don't seem to be willing to use the right metal for the plate, or to heat it enough while pumping the vacuum. They are also very poorly made mechanically. Between both these factors, they are VERY likely to go cherry red on you, possibly when you're not in the room to notice. You are very lucky that your last cherry red incident didn't damage the amplifier's output transformer! You might not be that lucky the next time, and the Chinese tubes would prove a very poor economy. (Try pricing a McIntosh output transformer.) Expensive Chinese KT-88's probably have just been tested more. Sure, they may measure good when shipped, but since there is so much occluded gas in the plate, they will go gassy just as fast as untested ones. Not worth the effort to smash them underfoot. I can't think of any reputable power amp vendor who ships with Chinese power tubes anymore, no matter who re-tests them. It's all GE, Russian, Czech, or Yugoslvian. Certainly, Stereophile's argument that 6550's aren't audio tubes is complete hogwash. Just look at Tung-Sol's advertisements from the late 1950's in Audio, Radio-Electronics, and Radio & Television News. However, there is a sizeable camp of folks who do not like the sound of GE power tubes. They certainly have very different mechanical construction from the "prototypical" tubes. For instance, their 6CA7/EL34 does not look like a Mullard EL34. It's a beam tube, not a true pentode. I doubt that it's "kinkless," which the Mullard EL34 was promoted to be. I've never done any comparative listening, so I can't comment on the sound. I'd say go ahead and buy the one Richardson KT-88 from McIntosh. Moreover, given the size of your investment in this amplifier, I'd order a spare set, since Richardson plans to stop making them. Maybe two spare sets. ($150 is less than you would pay for a never-used English GEC KT-88.) They are the best KT-88/6550 class tube available today. The one other reasonably safe alternative is the Russian 6550W. Audio Research is using them. The Russians do know how to pump the vacuum in a power tube. They _do_ have some quality control problems, so do buy them from someone who takes them out of the box and tests them. (By the way, tubes have traditionally sold with a 90 day warranty. Your failure may have been covered by warranty.)