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In Reply to: RE: Mcintosh Tubes posted by Michael Samra on June 25, 2016 at 21:57:54
This is a Mac KT88 tube which is made by SED in St Petersburg Russia
" This is an SED KT88 made by SED in St Petersburg Russia.They are identical in every way.The only difference is,Mac had their name put on the tubes but they build them the same way they do for themselves and other customers.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
Follow Ups:
Thanks for your thoughtful replies. I will address them individually. I think a well wired Citation II with an upgraded power supply. (McShane does this too) are great amps, possibly a bit sterile for my tastes but they have great transformers, although I suspect Mcintosh used a little better proprietary wire to wind theirs. However, the point is that Mcintosh knocks it out of the park 90% of the time and has for 60 years. Not once or twice.In fact look at most Citation II's in the straight used market and compare them to a MC 30 on up. The Citations have to be rebuilt, the Mac gear might need a few caps.Based on Mac's brain trust why would you question their choice of tubes.
(now for the 2nd reply, it applies to the first one)
A picture may look quite similar but I can tell its the things you can't easily see that make the difference. The thickness of the glass on Mac tubes (its much thicker than RCA, Sylvania, ect. NOS tubes). The conductors specified, the exact type and structure of the conductors they require. They also bin select their tubes only accepting those which test in say the top 20%.
Again its far more subtle than a picture and do you really think for $9000 and much more they charge for a tube amp the most demanding engineers in the business are going to pick a $10 or $20 inferior tube?
Stewart
Edits: 06/26/16
Actually,McIntosh gear is priced very reasonably in comparison to other high end gear.It's a lot like a Corvette or a collector car where you have depreciation the first few years and once they age,their values starts to climb again.
The only thing I don't like about a lot of the new gear is the fact they use circuit boards..You are an EE so you know that when mounting components on circuit boards,the only conductivity the component leads have to the circuit board is thru the solder itself.In a point to point wiring situation,the component lead or wire is wrapped around the end connection and then soldered for added insurance..This way we don't deal with electron disassociation so much. While circuit boards are ok to use in many situations,when you get into high voltage and higher current situations as we do with vacuum tube output and driver stages, things can be somewhat compromised especially once the connection starts to age over time.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
This is the Mcintosh KT88 that is made by JJ.
This is the same tube with JJ's label on it.
I need to address a couple things here.
A picture may look quite similar but I can tell its the things you can't easily see that make the difference. The thickness of the glass on Mac tubes (its much thicker than RCA, Sylvania, ect. NOS tubes). The conductors specified, the exact type and structure of the conductors they require. They also bin select their tubes only accepting those which test in say the top 20%.The tubes you are referring to are the JJ KT88s and those have MUCH thicker glass than the SED KT88s...Look at the very top of the tubes you are no doubt referring to and you will see that the top of the tube has a narrow hat like top on it,indicating that it's a JJ KT88 tube.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
Edits: 06/26/16
I am talking about 12AX7's.
Stewart
One can't help but be impressed by your enthusiasm for McIntosh gear and your obvious devotion to it. However, you also seem to be impressed by the cost of that gear and equate cost with value. I don't think anyone wants to dampen your enthusiasm, but all the respondents are attempting to do is to temper you starry eyed devotion with a slight dose of reality.
A case in point is the KT88 made by SED in St. Petersburg Russia. Yes, it is possible that these McIntosh tubes have a more severe burn in and may be tested to a higher tolerance, that's quite plausible, but to further assert that they are somehow different in construction shows a certain naivete. There are domestic tube vendors that do a very similar burn in procedure because they know from experience what is important. They may charge extra for this service but not even close to the cost of tubes with gold writing on them.
I am happy that you enjoy your McIntosh gear and that you believe that you are receiving good value, but here on Tube DIY there are amateurs that build their own gear that can compete with McIntosh for technical specification e.g., the same frequency response and low distortion of the McIntosh products. That's just a fact. But it is sound quality, subtlety and refinement that we amateurs find compelling, definitely not distortion specifications or frequency response since they are easy to achieve, particularly with negative feedback. There is nothing wrong with negative feedback when properly applied, but many of us have noticed a correlation between negative feedback and dynamics and choose to have realistic dynamics rather than a ruler flat frequency response. That's the point: when you build your own gear you can tailor it to your own tastes, not to some technical ideal. When you build only one or two pieces you can afford to install superb quality components because you are only buying a few of each not hundreds or thousands. There are very clever audio engineers here on this board that build experimental circuits using rare or uncommon tubes. There is no reason to use a 6DJ8, 12AX7, or 12AT7 in gear you make yourself because you are not relying on current production tubes. McIntosh is forced to use tubes that are current production: their market demands it. A case in point is my latest build. I could have used a 6SL7 or a 12AT7 but instead chose the 6K5GT. Why? Because they sound much cleaner and have less distortion than the above tubes, perhaps because they have cylindrical plates. The primary difference is that McIntosh gear is built in large quantities and must use commonly available components; the amateur only has to build one or two examples and can pick and choose from a variety of sources, some quite rare or severely expensive.
The McIntosh gear is intended to be a showcase, to generate pride of ownership (quite successfully in your case); it is gear you can show off to your less well healed friends. It is like showing up at the country club in the latest model Ferrari when your friends have to drive a Lexus or BMW.
McIntosh is one of the best as commercial offerings go. But for sonics, this gear is easily bested by a well designed SET or push-pull triodes. That's why some of us build own own, or in some cases, modify an original. Like most things, once the limitations of mass marketing and profit are removed, improvements are relatively easy. Considering the context of this forum, I'm not even sure why we're discussing McIntosh specifications. Really, who cares?
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Buy Chinese. Bury freedom.
Again.\, thanks for your thoughts and ideas. They are appreciated. Any day my "truths" are sincerely challenged is a good day.
If I gave the impression the cost of the gear is the gating item,please let me correct that notion. Mcintosh may be expensive but I am impressed by the caliber of its design, and thus its design engineers. I have a BSEE, an MSEE, anMSCIS, and although somewhat irrelevant in this discussion an MBA (Finance/economics). I appreciate the cleverness and committment of Gow et.al. These guys led the way in many respects, as did Hafler, Carver,Shearer,Lansing, and the Chief Scientist at HK (forget his name). Although I took a number of electronics and solid state classes in school, my engineering professional career was in signal processing i.e. Radar and Electronic Warfare systems. Now that I am at the stage in life I am free to pursue things simply for the personal joy of them, I study speaker design, tube electronics, ect. and appreciate the pillars of the crafts irrespective of the retail cost of their contributions.
EX: I just rebuilt 2 PAS preamps. The line amp stage, the Phono stage, and the power supplies are only distantly related to Haflers designs. I just had them tested and they produce .1% THD yet cost a tenth of a Mcintosh preamp. By the way, the boards were designed by a guy named Waters at DynacoDesigns.com. A guy there did the rebuild and the workmanship is a thing of beauty. Extraordinarily clean and the wiring is magnificent. Very orderly and wonderful soldering.Again, because of the quality of the design I would stack these up against Mcintosh and they cost well under $1000 each. They just look like a PAS instead of the Mac glass or super polished stainless. WHO CARES.
And really, if we are discussing cost what does Mcshane charge for his Citation restorations? I think its over $3000 for an amp that was a $200 kit when released. (They are quite pretty)
Stewart
"Based on Mac's brain trust why would you question their choice of tubes."
Because they used the cheapest phase splitter that was a pin-pin match with the rest of the tubes they use. As to this glass thickness, you have noticed something successfully; some new tubes have thicker glass than their Original Era counterparts made domestically.
As to this claim on McIntosh selecting criteria, do provide some proof, I'd love to see it.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
I own Mac 12ax7's (as an example) and have owned, or currently own Sylvania, GE,RCA, Tele's , Mullard, Sugaung, Mataushita, EH, JJ, and I am guessing others over the years. The Macs are the heaviest..and its very noticeable.
By the way....When I test THD and frequency response it is ALWAYS at the rated power......in the case of an MC275 MK IV that would be 75 w/ch, not 1 watt. The frequency response is like nothing I have ever seen.......completely flat from 20 to 20Khz.
In all seriousness, tell me how to post the print out and I will. It is just freaky to see what these guys build.
Peace
Stewart
Nobody made special tubes so McIntosh could select them...OMG, I don't think you have any idea how ridiculous that is.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
I am afraid you are wrong in a number of ways.
First it is is very common for firms to specify specific characteristics they want in a product they sell under their label. As an example when you buy a a tire, many other things at Walmart it may say Goodyear so and so, but it is Walmarts version. They tell the vendor what price point they have to hit,what physical characteristics must be there and what can be ignored. The vendor then comes back with a product that they can build to meet Walmarts directives. Its the same with anyone else.
Somethings in tubes (which are easy to build with the right tooling) may be as simple and binning ( taking only those which test in the top 10%). It may be using certain conductors, it may be the top 10% of glass qhality,it may be who knows what. Money buys anything.
Stewart
You are right in that the tube manufacturer doesn't make a different structured tube for an audio manufacturer however,it was very common for high end audio manufacturers like Fisher and Mcintosh to get better testing tubes to their specs for overall data,especially when the tube company puts the Mcintosh or Fisher logo on the tubes..Mcintosh doesn't personally go to the JJ or SED factory and hand select tubes,they do however get the best testing tubes and they pay extra for this especially when their name is going on it. JJ no doubt hand picks the tubes to meet the specs McIntosh requested before they print the logo on them. All in all they are still selected from same batches of production tubes,they just test better.
I was surprised to learn a few years back there were were A and B stock tubes..It sort of reminds you of when the auto industry rejects millions of tires each year from the tire companies because they don't meet the car manufacturer's standards,even tho they are perfectly good tires.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
Edits: 06/27/16
"it was very common for high end audio manufacturers like Fisher and Mcintosh to get better testing tubes"
That's absolutely correct. I've always been disappointed by the section-to-section and tube-to-tube variation in RCA 'SN7s. However, a few years ago I bought some of these that no one else seemed to want because they were labeled "Zenith." The matching on those tubes was unlike any I've ever seen, so good I wouldn't hesitate to just pull them out of the box and install them in an amp as-is. After seeing that, I went back to the seller and bought all he had. :)
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Buy Chinese. Bury freedom.
Back in 2005 on Ebay,a gentleman was selling these NOS/NIB Fisher branded EL37s.Of course these are Mullards but anyway these tubes came from a Fisher warranty service center back in 1968 and he worked there and had them all that time..He was selling for them for 90 dollars each and I bought the last two he had.He didn't sell these as matched tubes but when I got them I had noticed the number 946 at the bottom and being they both had this number,I thought I would throw them in my Heath TT-1 and they both tested identically on mutual conductance and emission and I mean to the number.I then put them in my maxi-matcher I made up out of a 475vdc power supply and biased thru 10 ohm resistors.I tested the tubes at 425vdc and minus 46 on G1 and the current draw was around 48ma as I recall but it was identical for both tubes. I then put them in my Fisher 80AZs which I have several and I measured plate temperature and even that was identical on both tubes when put them in the same socket and i measured at several different points.
Ten months later to the day almost I found another vendor selling some of these same tubes but he was in Parsipinni NJ where the other guy was in Chatsworth CA.I got two more of the same type NOS/NIB branded Fisher EL37s for 190 for the pair this time..I got these tubes a couple days later only to find out these tubes also have that same 946 code..That made me put all four of them in a friend's real Maxi-matcher and all four drew identical amounts of current at the 400vdc voltage..These four tubes were perfectly matched in everyway from mutual conductance,emission,plate temperature,and in even the maxi-matcher.
That's when I realized why this had to be.Being these were factory replacement tubes,the Fisher amps that use EL37s have no bias adjustment, so these tubes had to be matched and ready to go when you dropped them in.
Since I don't have a curve tracer,I match my tubes in a more primitive manner but it at least tells you they possess very similar characteristics.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
Edits: 06/28/16
By the way....When I test THD and frequency response it is ALWAYS at the rated power......in the case of an MC275 MK IV that would be 75 w/ch, not 1 watt. The frequency response is like nothing I have ever seen.......completely flat from 20 to 20Khz.I think you were addressing me on that question but nobody denies the specs that Mac amps are able to produce because they are absolutely marvel in design with their output trafos and overall execution of the driver,voltage amp, and nested loop FB. The early reissues didn't make rated power but I blame that on govt regulation because they were running a lower B+ so they could meet UL specs and they wanted to keep the original look..After customers started complaining about not making rated power,they made a change to where they put part of the output tube bases below the chassis and then put heat venting holes around the tubes and then raised the B+ up accordingly.
McIntosh, like other commercial designs,would often cut corners in some areas even back in the early days.I own six Mc60s and one of the amps was born without a choke and yet,the holes are there for a choke to be installed.They did have a few iterations of this amp so maybe this particular one was setup for a background music system in a commercial application..I ended up putting a choke in so it matched the other five but also,Mac used to used to use copper lined chassis in many of their earliest Mc30 and Mc60s and that was done away with as well. The Mc30s all should have had a choke installed by the mere fact of the amount of current the amp draws at or near full power. Mac also used bias windings on some Mc30s and Mc60s and some they didn't.They would take the AC off one half of the high voltage secondary,put in a dropping resistor.and then rectify it..It's ok to do this but it is kind of cheezy when you think about it. My point is,even the best companies are not immune to the bean counters.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
Edits: 06/26/16
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