aerius

Well, there's this slight problem of making a push-pull amp run with a single-ended transformer...

To broadly generalize. Ultralinear: More power & dynamics, flatter & more extended frequency response. Triode: More midrange goodness & better tone, but at the expense of the above. I don't have much experience with 6SL7's or EL34's so I can't recommend those. For the 6SN7 I'd probably start with the GE 6SN7GTA, not to be confused with the GTB which looks the same but sounds a lot worse. The GE 'GTA is pretty neutral sounding and dynamic, though it's not the last word in detail & refinement. It gives a good starting point to play around with the other tubes, and once that's done you can explore the more exotic (read as "stupidly expensive") 6SN7 options. My favourite is the RCA grey glass 6SN7 for its full rich tone and large soundstage, but on some tube amps it'll make things too warm and mushy.

It's so rare and expensive that it only costs $8.50. Vacuumtubes.net is selling them for about the same price, and I recently had a dozen shipped to me for under $80 from a guy on diyaudio.com. These are not rare tubes by any stretch.

Where do these crazy rumours come from?

A quick back of envelope calculation says it should be entirely possible. I built mine for under $100 CDN, but I bought a lot of the parts used from a local surplus store. The big expenses will be the transformers, the choke, and the motor-run capacitors, that might add up to maybe $200-250, everything else is literally a few dozen dollars. I used Cat6 network cable to do all the wiring since I had a ton of it lying around. I'll draw up a schematic for the DC tube filament supply after I get mine dialed in, it's running a little higher than I'd like with the 37's, I want it to run at 5.9V-6V instead of the nominal 6.3V

Thanks! It is indeed built on a piece of perfboard/stripboard or whatever they call a board with a bunch of holes in it in your part of the world. I just drilled the holes for the sockets with some large wood bits on my powerdrill and glued the sockets in place, then put the supports & standoffs near the sockets so I don't break the board when putting in the tubes.

Yup. Except it'll be the Swedish women's bikini babes and not a bunch of butch Amazons.

New and improved, now with the wonderful 37 tube as the input. A 37 for each channel, then to an ECC40 (a dual triode) which does the phase-splitting for both channels, then to the output tubes. This is much better for Grados as it significantly lowers the gain and makes the volume knob a lot more useful. You can also use a 76 which has a tad more gain, but nowhere near as much as the ECC40. These tubes are still pretty cheap, $10 give or take $5 or so, but you might have to hunt around a bit. I think they sound better than the ECC40 as well, but I'll have to borrow a better source to be sure. My recommendations would be as follows. For Grados and other low impedance 'phones, build it with 37's. For Senns & AKG's, go with the higher gain all ECC40 version.

Other. I choose to be fucked to death by the Swedish Bikini Team. If I gotta go, I'm going with a big fucking grin my face and the best damn orgasms any man has ever experienced.

I'm trying to make sense of the Doge circuit, but either it's too early in the morning or something's really weird. It looks like a cathode-follower input to a common-cathode gain stage which then feeds the trioded output tube. Other than dropping gain, I can't figure out a reason for a cathode-follower input, and the 330k resistor puzzles me as well. It's just not making sense to me, I don't know if it's some brilliant concept which is way over my head or an amateur hackjob.

I've heard it, it's decent and performs at its pricepoint. The big problem is the electrolytic capacitor on the output which will mess up the sound, along with the 10k plate resistors on the 6SN7's in the cascode which are too low and will lead to excess distortion. Ideally, the plate resistors should be about 5-10 times the resistance of the tube's plate impedance, the Rp of a 6SN7 is about 7.7k. I'm guessing that the Chinese ripped off a 6DJ8 circuit and swapped in 6SN7's without bothering to fix the circuit. Interesting, want to post the improved circuit? There's a surplus shop in my area and I should be able to find the parts to build it.

Yup, now you gotta find a new source for Reks to buy so you can scoop up his Audio Aero Capitole.

And here, we see the trickle down theory of economics in effect...

Thanks to a person on DIYaudio.com who had a blown MOSFET on this PH12, we now have this wonderful schematic so we can all clone "the best amp in the world that's ever been built", that is if you believe dretardwells.

Speaking of masturbation machines, I tell you, women get all the best toys. Like the Dorky Donkey.

B.B. King at Roy Thomson Hall last night. I had to hear the Blues legend again before he passes on.

In theory the output impedance should be a bit over 4 Ohms with 6BL7's and about half that with 6BX7's, however I've never measured it so I have no idea what it actually is in real life. I do know that it'll drive 6 Ohm speakers with either tube so the output Z can't be too bad.

Stop visiting teen porn sites?

Yeah, they omit everything which makes music good.

I think it makes a lot of sense from a commercial standpoint. The trend in mainstream hi-fi has been towards "accuracy & neutrality", and the K701 sounds pretty "accurate & neutral" unless the person's heard something like the HP-1000 or K1000 which actually is accurate & neutral. They're a company, they gotta follow the market to some extent to stay profitable.

Sing along to some Frank Zappa: "Catholic girls, She gave me VD!"

But did you break them in for 10,000 hours and run them with the special K701-approved amp, source, and cables? Speaking seriously again, I agree on all points. I'm still trying to understand how people think the K701 has a great midrange and what they're comparing it to, the midrange to me is among the most dry, flat, and dead sounding midrange I've heard in any headphone. It discombobulates me.

I have quite a bit of experience on both sides, as a customer and as the guy who had to answer the phones and deal with customers at a small business. From the business side, if a customer calls me only once a month or once every 2 months, he probably doesn't care too much and I can string him along as long as I damn well please. Yes yes we've been terribly busy, we're very sorry and we'll get to it as soon as we can. Click. And we're good for at least another month when we get to do it all over again. I spend 5-10 minutes on the phone every month or two and I don't have to do jack shit about him. I can just let him hang while I do more profitable projects. On the other hand a customer who calls in every day and goes "is it fucking done yet?" and gives us shit for our excuses (real or not) gets very annoying very fast. After a short while of dealing with the cockmunch, we just want to get the asshole out of our lives any way we can. So we buckle down, do his project ahead of the others and send him on his way, then we hope to god we never have to deal with the goddamn fucker again.

The key is to make enough of a pest of yourself so that he makes the time to work on the amp. This is known as the "squeaky wheel gets the grease" theory of customer service. If you don't bitch enough, he ain't gonna serve you until he feels like it, which may be never, if you call him up every day and go "where's my amp? I want my fucking amp done now or else!" he will break down and get your amp done, and if he doesn't then you fuck him up good on Head-fi.

Let's just say his idea of a headphone amp is a single stage OTL using a 6H30P. It had an output impedance of something like 500 Ohms and no bass. Unfortunately I didn't know that much about tube design back then or I would've told Jay to tell Ori that he's a fucking crackhead for coming up with something that dumb.