jon_010101

I have a single MC30 that's a pretty good match to that one -- 9e vs. 7e serial number but close! Let me know if you want to sell, trade, or buy

Nice decorative mini system on the top shelf! My housemate's Aiwa sits among my tube amps and gear, mostly for aesthetic contrast []

That is, by far, my favorite engineer joke of all-time :-)

Oh it can be, and often is... but it takes money, good parts selection, and engineering effort, which is usually saved for amps well beyond "klub" status. ;-) A note... not just "klub" amps are guilty. Here's a very expensive audiophile amp that's looking pretty guilty LINK.

Hi Roy, This is only a disagreement of language here, and it's really my fault -- When I say distortion, I mean to say "nonlinear distortion", i.e., added stuff that isn't supposed to be there. This is different than just boosting the level of the high frequencies relative to the low frequencies, which is easily reversible. Frankly, I don't prefer a forward treble, but I'd much rather that than a distorted treble. My complaint of monster PA solid-state amps is that they are optimized for low distortion at very high output levels. I generally listen to music at lower levels through relatively efficient speakers, and prefer an amplifier optimized for low distortion at low output levels. There are many technical reasons for this, which are measurable in addition to audible. So, I was simply trying to make a counter-argument to DrWho in objective terms, rather than subjective description.

"many audiophiles value low distortion...over ruler flat response" is what I said. Some don't, and listen to some pretty weird-sounding systems. And, as we all know, everyone has different tolerance for different kinds of distortion. What I mean is that linear variations in frequency response are usually considered less objectionable than nonlinear distortions. It's a difference between a bit of EQ, and actually adding something that isn't supposed to be there. For example, I'd prefer a slightly-forward treble that was super-clean and undistorted, to a perfectly flat treble response that exhibited ringing and breakup due to nonlinearities of the tweeter.

Thanks Mark! This is all very true. A square wave can only say so much. And, while it is often great fun to hear every bit of information extracted from a two-mic stereo recording, I never really enjoy listening to the total accumulated weirdness present in some heavily-processed mixes. ;-)

This reminds me of an interesting experiment I saw posted on diyaudio.com. A fellow first connected a solid state amp, then a single ended triode amp, to a speaker and measured harmonic distortion, comparing distortion levels at the amps' outputs and the distortion in the room. The single ended amp's distortion measured much higher at the output, but somewhat lower in the room, due to cancellation with the speaker's distortion. This result basically blew my mind, but it makes physical sense (and also demonstrates how high speaker distortion can be compared to amp distortion). Be sure to check out part 2, linked at the bottom... it gets even more interesting. link Of course, this is only a consideration of harmonic distortion, not frequency response, or resolution of transients or anything else, but I do get the impression that many audiophiles value low distortion (and non-objectionable vs. objectionable distortion) over ruler-flat response. Personally, I like having low distortion, high resolution, and natural response whenever possible, but distortion is in my opinion the worse of these evils ;-)

"Distortion in Power Ampfliers" by Douglas Self (on google) has some great examples of class B distortion. Not all "klub" amps are a trainwreck, but very few are optimized for lower power use, in contrast with a class A tube circuit (or even an audiophile solid state circuit -- or something designed for monitoring / mastering vs. concerts). BTW, Self's work for Cambridge on the 840A is worthy of much respect -- a clever method to transition between class A at low powers and class B for higher power, while avoiding AB operation. Even magazine measurements from stereophile or soundstage.com often show signs of various forms of crossover distortion -- and many tube amps (class A push-pull especially) will out-measure the sand-amp competition at the crucial territory around 1W output. Any engineers feel free to correct or disagree with me here, though -- I'm a EE, but circuits are truly not my expertise.

DrWho, the appeal of klub amps lies in their efficiency, and their ability to produce relatively undistorted sound while pushing 100 Watts of power all day long. However, in an audio context, especially in a high efficiency system, they are simply too blunt of an object. When you have a bunch of class B stages running at LOW power, the amplifier becomes completely crippled by crossover distortion, and will actually exhibit greater distortion than a fine tube amp. Many push pull class A tube amps will have about 6dB less distortion than a typical class B solid state amp when measured at 1 Watt output power. And, that tube distortion is going to be primarily low-order -- 2nd, 3rd, and 4th harmonics. Nothing too awful. The klub amp will be producing far more "nasty" distortion, almost like a correlated noise signal riding on top of your music. Hence that grayed-out, crunchy, dry sound of a solid state amp at low power. Imagine using photoshop and trying to "sharpen" an image until the edges are pixelated. There's actually a loss of information. Certainly this can be avoided -- as engineers have know for a long time -- by using class A amplification stages for small signals with wide dynamic range. This isn't some conspiracy of audiophiles against pro audio guys. But each truly has a unique set of needs, which engineers know how to address, and which both groups need to understand. I love the sound of a good pro rig -- but take that system out of its element, and idle it along at 1W output, and the results will just not be as satisfying. By the way, this also applies to preamps with op-amp stages. Take a look at op-amp data sheets and see how the distortion looks at 0.1Vrms output compared to 5Vrms output. If you are driving an amp, and need a low voltage signal (often <<.1Vrms), a tube gain stage can be a better source. That said, I have no problem with op-amps for gain stages, or output stages of line-level devices -- tuners, CD players, and phono preamps, where they can actually work a bit. But they, again, become a blunt instrument when driving a hifi power amp with a relatively tiny signal. A tube driving a transformer can be a much more elegant solution if one is willing to pay for it. This is the same reason why good tube or discrete FET microphones sound so much better than an op-amp mic. Efficiency rarely comes without sacrifice, and without added (avoidable) complexity. JMHO. BTW, Mark deserves a prize for his telescope analogy! I don't post much on this forum, but this thread was too interesting to avoid.

AR1 speakers (not sure about the 1Ax) are generally just a big woofer and large midrange driver -- but that midrange is sometimes an Altec 755, which is quite desirable (and valuable). You might want to do some research on them. It should be either possible to restore them, to "borrow" the 755s (if present) for use with some tube amps, or to pass them on to an AR collector. I'd bet that the woofer has a cloth surround, so it may still be in usable condition. Perhaps take a look at http://www.classicspeakerpages.net/ for info (they do have an AR forum, too). These are rare speakers, and are rather highly prized, although perhaps more for their historical significance than their sound. G'luck!

Ha! Record Connection is a great store, with a huge selection of progressive/psychedelic rock CDs, and good cheap vinyl. On the topic of the BB, looks like I need to track down a copy of Stereophile to satisfy my curiosity. Very exciting news.

http://cgi.ebay.com/4-PCS-SPRAGUE-BUMBLE-BEE-0-22uF-600VDC-CAPACITORS_W0QQitemZ270025312644QQihZ017QQcategoryZ71573QQrdZ1QQcmdZViewItem On the topic of bumble bee caps, can you imagine someone buying these to use in an amplifier?!?!?!? []

Hi Carl, Saving the components in a bag is a good idea, just for the sake of history. At the same time, no sane person would ever want to reinstall them. I have all of the bumble bees and oozing (literally!) paper-in-oil caps from a few amp projects and, really, they are nothing more than toxic waste in a box. If I ever sell any of my amps though, I'll certainly pass them on for the sake of history and completeness. I read somewhere that even Sid Smith himself re-did and extensively tweaked most of his Marantz amps over time. Knowing this inspired me to make some upgrades in my Radio Craftsmen 500a's (also a Sid Smith design) ... polypropylene power supply caps, etc., where previously I had kept things to 1950's-style parts only :-) As long as I keep the component values and external appearance original, I don't feel like I'm stomping on history.

McIntosh and Marantz collectors can be the same way... it's kinda sad... all of those guys are in for a very nasty surprise when the bumble bees (inevitably) short out and fry their tubes and/or output transformers (which are a lot more valuable than a 50 year old paper/mylar film cap). I've yet to find a vintage paper/mylar cap that didn't fail within a few months of use, if it wasn't shorted already. Old electrolytic can caps are probably more reliable than bumble bees. They DO sound pretty good while they last... but there are plenty of modern equivalent mylar or paper film caps which will be more reliable.

Regarding the 12X4, Angela electronics has tons for sale on eBay... I picked up four RCA in boxes for $10 total, just so I'd have some backups. I tried a new-in-box Amperex HZ81 / 12X4 (the only substitute I am aware of) and was shocked that the sound changed dramatically. Not really for the better... just tubier. Faster-sounding but minus the bass, and more euphonic. Perhaps it was changing the plate voltage a bit? I have tried a lot of 6DJ8 combinations ... some surprises. For the follower stage, I usually prefer a newer construction tube, or a cheapie NOS. The stock JJ's give a darker sound, versus a brighter sound from Russian 6N23P. Right now I have some RCA/Mullard 6DJ8's in the follower stage which sound very nice, about halfway between the JJ and 6N23P. I've tried American-made GE tubes (Amperex? Sylvania?) and they are closer to the JJ's with a darker sound, but tend to be muddy or bloomy for this application. Amperex is fine, but seems like overkill; I'd rather preserve the good stuff for the gain stage... In the triode gain stage, I have had the following observations (no particular order): 1) JJ's -- very clean with very fast top-end, but a slightly recessed midrange 2) Ei Elite -- stock tube, nice crunchy top end, slightly dark/dry sounding, but nicely detailed. 3) GE smoked-glass -- warm, pleasant, not in-your-face, natural. Sounds really nice with 6N23Ps in the follower, really boring with JJ's. 4) Amperex Holland Bugle Boy -- similar to GE, but more 3D, clear, and colorful, but arguably less natural 5) Amperex Holland PQ orange label 6DJ8 -- huge sound with gorgeous midrange, very high gain, but gets a bit fatiguing. Mine all are too noisy to use. 6) 6N23P -- clean, dry, detailed, a bit grainy, but I bet these can be really nice in the right system and they cost very little on ebay. 7) 6N1P -- bass-shy, not really a great substitute in the Peach, very clean, but kinda weird-sounding. I plan to use mine in a power amp project. 8) RCA "Holland" -- sounds suspiciously like a Bugle Boy 9) RCA "Gt. Britain" -- sounds presumably like a Mullard, next up for me to try Honestly, I could be perfectly happy with a very basic NOS American or European tube and a pair of 6N23P's... total cost, $10-30 ebay + shipping []