aerius

The answer to both questions is at this point "I have no freakin' clue!", unfortunately. I've barely started reading up on DHT designs and familiarizing myself with their design concepts and how they work, I just don't know enough about them right now. I have bits & pieces here & there and some things carry over from IDHT's, but I'm still quite a ways from putting together to make a working picture. One of the instrumentation guys at my friend's company, apparently he used to build 'scopes & other stuff at Tektronics. I have the schematics for the amp but not the PSU, but don't even think about building it. I'm told the 6C45P is twitchy as hell, so the wire routing and grounding has to be absolutely perfect. It took the guy a couple tries to get it right and he has many years of experience with high-performance tube circuits, so us mere mortals are most likely SOL.

I doubt the Bugle 45 will be as good. There's a reason the designer has since moved on to using WE417A & 437A along with 6C45P tubes in his designs. More power, more goodness, less distortion. The Bugle's a good amp, but it still leaves a fair bit of the 45's potential "in the tube". Actually I was quite interested in the technical aspects of my friend's 2A3 amp. One of the coolest things was what's known as the Western Electric Harmonic Balancer, it substantially reduces 3rd & higher order harmonics and makes the sound a lot cleaner. It cancels out harmonics the same way Broskie's Aikido circuit cancels out PSU noise, by using it against itself. Apparently, this distortion reduction technique was invented over 70 years ago and then forgotten about for decades. Flat pads, the way god meant them to be used, IMO.

The RS-1 was redone with copper litz wire, didn't ask who made it though. It also had some mods done to the drivers. Basically, take everything about an RS-1 that's not so good and make it all go away, or almost all of it. Then take all the things that the RS-1 does well and crank it up to 11.

Impressions. Today I heard the best headphone setup I've ever heard in my life, and by a good sized margin, it was one of those rare experiences which redefines for me what is possible with headphones. I learned that a tweaked & recabled RS-1 is capable of shockingly good sound, it made my K340 sound broken and smoked it in everything except soundstage size. That ain't an easy thing to do. I also now know that I MUST build a DHT amp, a great DHT amp is as far above my amp as my amp is above an entry level tube amp. It's not a "yeah there's a bit of a difference", it was literally a "Holy fucking shit!!!" kind of difference. The Capitole CDP, well, not much needs to be said about that other than it fucking rocks. I'll start with the amp, it's a balanced amp using a transformer phase-splitter input to a pair of 6C45P tubes, to a switchable interstage transformer to a pair of 2A3's, then the output transformer. CCS's everywhere with glowy VR tubes and a separate tube rectified PSU with damper diodes & those motor run caps I love. What hit me from the start was the resolution, speed, and texture, it was like making a jump from 128k MP3 to the original CD, there's just more of everything which I never knew was there. One of the first songs I played was "Sweet Ones" by Sarah Slean, fun song which I hadn't heard in a while since I overplayed it a few months ago. Anyways I always figured the chorus part was just multitracked vocals with a bit of a chorus effect, but I found out through the amp & RS-1 that it was a lot more than that. Today, I heard that each vocal track got its own chorus & echo effect before getting multi-tracked, and the last chorus of the song had a vocal track which was itself multi-tracked. The ability of the amp to resolve and separate out all that in the middle of a band playing full-out is freakin' wild, I've never heard this kind of resolution before, even on a high-end speaker rig. Talk about hearing all the layers of the recording, this was nuts. It was pretty much the same idea for the next few songs I played, it got pretty intense. We took a short break while I redid the wires on my K340 so I could use it with the amp, and redid my amp so she could use the RS-1 with it. Then we flipped the amp to high-gain and plugged in my K340. Going from the RS-1 it was a letdown, yes the K340 sounds better than it does in my system but it still got stomped. It fell far short of the speed & resolution of the RS-1, it was congested & confused, especially in the bass & upper midrange where it couldn't get textures right and blurred tones & details. Guitar notes & tones sound a bit too alike, for instance SRV's Fender and Albert King's Gibson start sounding a tad similar when they're jamming and playing fast & hard with the band going full-tilt. When things get busy & loud, the K340 starts losing its ability to keep sounds separate and prevent them from blending. Same idea in the bass, the K340 isn't fast enough to keep notes from blending and more importantly, preserve the unique tone & texture of each note from each instrument. These are usually the strongpoints of my K340, and it's handily beaten almost every headphone in these areas, and here it was getting wasted by an RS-1. I haven't experienced anything like this since my first Head-fi meet, where Biggie's RS-1 setup make my Senn 580 sound like a broken piece of crap. Oddly enough, the RS-1 strikes again. After a break for snacks we got back to more listening, this time with both tube amps running off the Capitole. It turns out that my amp still has some performance left "in the bag" and my CD player is definitely holding it back a bit. It and my K340 are pretty well matched in performance though, so neither of them is really holding the other back. The RS-1 sounds better out of my amp now than it did out of my CDP, but it's still got a ways to go to match the 2A3 amp. 27's, 37's, ECC40's, 1633's, and 6BL7's are pretty good tubes, but they ain't DHT's. There's still a big gap in speed, resolution, tone & texture, and the ability to yank out those low-level details from a recording making it sound whole and complete. It was around this point where I remembered something I first heard from the guys at Fab Audio, that is, a CDR copy can sound different and sometimes better than the original. So we decided to test that one out, and I'll be damned cause it's true. In this case, we both agreed that the CDR copies sounded better, it was pretty much impossible to tell the difference with my K340, but with her RS-1 it was fairly apparent, though it's not that big of a difference. The CDR is more analog-like, there's more space and blackness which allows a bit more of those low-level details to come through. It's a little smoother & more musical, and I think for long listening sessions this could all add up to a big difference in enjoyment and lack of fatigue. This was a consistent difference we noted with all the CDR copies I had on hand to compare to the originals. I guess this means I'll have a lot of CD copying to do if my system ever gets good enough. For those who want to try and replicate this, my CDR copies were burned at 4X on a Matsushita 32/8/4 CDR/W on Fujifilm (Taiyo Yuden) CDRs after ripping on EAC on secure mode. Stay tuned for more...I'm still trying to digest and think over today's events.

I'm currently taking a break from a mini-meet, it got pretty intense and my friend & I are taking a break to go grab some food and catch up on things a bit before returning to the listening. A little teaser, we have a modded Audio Aero Capitole, a custom built 2A3 amp, and a balanced RS-1 recabled with copper litz wire. For shits & giggles, we decided to compare a regular store bought CD (Tori Amos - Boys for Pele) with a CDR copy burned on a Fujifilm CDR. I've heard people saying CDRs sound better but never heard a difference on my system, so since we had a top-notch system at our disposal we decided to test it out. Shockingly, the CDR sounds better, and I was like "what the fuck?!" More to come later...

Here it is in rough schematic form, please excuse the lousy handwriting.

But they use them in the $20,000 (or whatever the hell it costs) Zanden, therefore it must be good! I don't think I've heard a DAC with one of those TDA chips, but I can't say it's a life experience I desperately need either. I have the PCM1700 in my CD player and like what it does, and I've heard the PCM1702 in Biggie's player and really liked that. The ones I do want to hear at some point are the PCM63 and PCM1704.

The funny part is how true that is. I've recently heard of TDA 154X chips going for the same price on ebay as a good NOS tube.

Heh heh heh, it's always hilarious to see immtbiker and the other mods get owned and made to look like retarded tools. On a sidenote, it's pretty true what Mike said a while back, once you get used to SD.net debating, you can ruin almost everyone at most other forums. On another sidenote, are you aware of the headphone fetish site? And finally, welcome to head-case!

I can't say I'm surprised. As they say, one man's garbage is another man's treasure...

That is pure comedy gold! Posting that on Head-fi will probably get you banned on the spot though.

Your mom's a dumb broad.

Hi, my name is aerius, and I'm fucking drunk. I'm posting on head-case while drunk. Boo-yah-kah fuck yeah!!!

Pick up some hot college chicks while you're at it.

Looks good as far as I can tell, I don't see any issues with it. The power supply's going to be a shitload of fun though, and not in a good way. Also, latest update on Art-tard.

Pretty soon I'll be able to find out first hand. I scored a couple used 2A3's at the surplus shop today ($3 each, bitch!) and I'm planning to build something with them this year. Also got a bunch of 6BQ5's, 12W6's, 0C3's, 0D3's and a big box of 6CM3 damper diodes. The GF is quite upset, but she'll get over it.

My first move would be to dump the 12AX7 tube, and then choose from either a 6SL7, 6SN7, ECC40, or 5687 depending on how much gain is needed. Next would be to put the gain stage first and then the cathode-follower, or dump the cathode-follower altogether. I still don't know what that 330k resistor does so we'll leave it for now, but removing it might be an option. All those 10k grid-stopper resistors can likely be dumped as well, with a good wiring layout you don't need them. Then you can play with fun stuff like LED biasing on the tubes and an ultrapath capacitor between the B+ end of the transformer and the cathode of the EL84.

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.