dsavitsk

Pictures would help (particularly around the connections to the tube sockets), but it sounds like a combination of things. There could be some grounding issues and any competent tube tech should be able to fix those. Additionally, the tubes could be oscillating due to poor construction. Oscillation can manifest itself in a lot of different ways, from static, to hash, to squealing, to microphonics, to ringing. 6sn7's are not known for a propensity to oscillate, but any tube can, given the right (or wrong) environment. Really, you'll need a scope to know if this is the case, but if there aren't measures to quell oscillation taken, then adding them is as good a test as any. This means adding grid stopers, and in extreme situations not likely here, plate and catjode stoppers as well. The tubes could also be picking up interference of some sort which would be cured with some shielding. As a first go, try making shields out of aluminum foil and wrapping them around the tubes. Literally, this means wrapping a tube of aluminum foil around the tubes. Be sure they are grounded to the chassis -- probably touching the screw that holds the socket on will be good. edit: ah, you are using those dumb tube adapters? Almost certainly oscillation. Could be other stuff, too, but those were a bad idea from day 1.

Boy that's ugly. Cary deserves credit for being a big player in the tube and SET revival. Also, the 805 is a beautiful amp. But otherwise it is all a bit underwhelming. As you mention, there are some real issues with the amp designs, not only in sound quality, but also in basic abuse of tubes. I used to own a 303-200 cd player, but I designed my own DAC that sounds better, and if I can do that, then there is something wrong. I do like their knobs, though.

In general, the issue with Cary amps is in the power supply. Typically several large, slow, caps with resistors instead of chokes. Since the caps don't stick up on this amp, you could rebuild on the inside to fix this without it showing. You could also probably just add some small film bypasses for an easy fix. A quick Google search didn't pull up the schematic, but someone must have it. They also tend to run everything right at the edge of dissipation limits (tubes and components.) You should be able to dial things back a bit if you are willing to get in and get your hands dirty. But, you could also build a much better amp for way less money if you are willing to do that. As for the "upgrades" ... These are fine caps, but they are not that expensive. A pair in the required size is about $45 at parts connexion right now. I say that, but it may be that their phase splitter needs a whole host of caps. It isn't clear whether they use these for all 8 that are likely required in a Schmitt -- I tend to doubt it, but it is worth a look under the hood. I thought it used 5U4's ... Anyway, another $5 upgrade. Makes you wonder what the stock version uses. That's nearly $2 worth of wire to rewire that one input. And, even if you are prone to thinking that wire matters, if you can tell the difference between that and some other copper for that short run, you have better ears than me.

Meet the Fonkens

It is probably not ideal, but it is also not necessarily a huge concern. My experience says that the lower the Z out the better for Grados, but anything up to about 8 or 9 ohms will have a decent damping factor, and assuming enough current will perform fine. You could, of course, use a stepdown transformer/autoformer of some sort to improve things.

Output impedance for a cathode follower is approximately ra/mu, or 1/Gm. For the standard 6080 used in a headphone amp, this is about 150 ohms (the reason they work at all is because there is a ton of current -- here's a good article on this). Less than warmth, this high Z out really just leads to flabby bass and lack of control for Low Z phones. OTL does often have warmth, but note the 3 signal path caps (output, interstage, and Rk bypass for the driver) in the standard design, plus the several PS caps that are also in the current loop.

Sorry I didn't quote that very well. I was attacking the article, not the messenger. The increased 2nd harmonic theory is stated over and over and has come to be accepted as truth. But, as I say, there really isn't any good evidence that it's true, and indeed, there are lots of reasons to think it is false. The cap theory is mine, and my experience seems to be that if you get the caps out of a circuit, you lose that sheen and bloat, but it could certainly be something else, too. -d

Better? http://www.youtube.com/watch?v=RzOQbmtzw2U

Thanks for the welcome!

Tubes do not "add warmth". Tubes are very linear devices -- much more so than transistors. The most likely culprit of the "added warmth" in many tube circuits are the multiple capacitors in the signal path, which do add warmth and distortion in spades. These can be designed out in many cases, but doing so is exceedingly rare. I've almost never seen it done in commercial gear. Also, the 2nd harmonic distortion thing is a dumb myth. If you want to convince yourself of this, use your computer to add 2nd harmonic distortion while you listen. It will not make your solid state gear sound like tube gear. It will make your solid state gear sound like solid state gear with a high 2nd harmonic component. Tube gear often sounds good in spite of the 2nd harmonic distortion, not because of it.

None of these (other than the EL34's) appear particularly valuable. These are about equivalent to the 6CD6GA. Decent power tube, but has a lowish screen grid limit. Could be used for a few watts in a power amp -- I wouldn't both for headphone duty. http://frank.pocnet.net/sheets/127/7/7867.pdf Here's a schematic using one, which you'll notice uses a lot of your tubes which may not be coincidence: http://www.triodeel.com/du1a475.gif Another low power output pentode (much lower power than the one above). Might be useful for a transformer coupled SE amp of some sort -- good for a couple of watts pentode, or less than a watt triode. http://frank.pocnet.net/sheets/127/2/25C5.pdf Close to an EL84, lower plate voltage iirc -- one of them is not going to do much for you.