kevin gilmore

those are heatsinks for the output transistors.

Krell made a wonderful headphone amp about 10 years ago. It was called the ksa25. Very few were made, it was something like $4k then. Atma-sphere makes some truely wonderful amps that drive headphones very well, kind of pricy. Don't see levinson (as in harman international) ever coming up with a headphone amp, they have enough trouble selling their current stuff. Conrad-johnson, vtl, rowland... that would be some nice stuff.

quoting granodemostasa Example 1: The B52 was one amazing product. I didn't like it to start with, but after hearing it on Billy's system I grew to have much respect for it as one of the top headphone amps out there. The apache wasn't the same. On the same piece of music, on the same headphones, the apache sounded like it had some amount of glare and "TV" around the music that seemed so clean and pure on the B52. Is anyone surprised at this. Ray said it himself numerous times. The thing is 2 x HR2 in one box. So he took a 10 year old headwize design with a class AB output stage and cramed it in one box for a price of somewhere between 2400 and 2900. Then he added a 1 opamp buffer as the preamp output. Its not a preamp, no remote control and no tape loop. And as a balanced headphone amp it has to be god awful. Evidently ray is aiming at the cordoba crowd. Corinthian leather. Its all about looks and the marvelous build quality. Screw the sound. Example 2: The new singlepower SS amp. For 1700 dollars i sort of expected an amplifier in the same performance range as the 1600$ zana deux, but instead i got something less than that. it was more or less equal to a balanced desktop and an apache, as opposed to belonging to the B52, dynamight, and Max balanced crowd. Surprise Surprise. At least it is supposed to be all discrete and mosfet output stage. But who knows... Example 4: the gold plated Maestro XLR- I really expected to hear the world lifted to a new level. instead i got fuzzy imaging, big power, and a particularly "singlepower" tube sound. It was good, just not the upgrade i'm looking for. mikhail needs to give up on the white cathode follower with put put tubes thing. For something that is that much money it could at least have been turned into an extreme with real output tubes. Then mikhail produces this miniature thing with no ventilation holes and people are telling me that it runs 30 degrees hotter than a raptor. THIS IS NOT A GOOD THING. Where is that talking heads album... burning down the house This commercialization thing is producing some amazing high priced junk.

One of the biggest and emerging problems is the head-fi international meet. Vendors are now virtually required to have new products at this show and are now driven by this yearly thing. So instead of coming out with rational new products when they are ready, many things are hurried along, sometimes putting current customers on the slow track so that more time can be spent coming up with new product that may or may not make any kind of financial sense...

time for a flyback line switcher i think

Now if we can just get those old high voltage mercury batteries, then the thing truely would be portable...

finally someone with a brain and the correct answer. However on some directly heated triodes the thoriated material on the fillament is actually quite toxic and known to cause cancer. Getter material is not very good for you either.

One will be a commercial amp, can't speak any more... The other is a bamaslama, you gotta build it yourself. (evidently a number of people have done so) Seeing the latest pictures you should be able to build a mcalister yourself. Its not possible to do any worse of a job....

My guess is that jason would like the singlepower extreme with 6as7's a lot. In which case there would be 2 more amplifiers that he would like even more.

first of all for completeness the numbers above are for unbalanced output. balanced output numbers slightly higher. Just for comparison (actual real numbers tested by me and i'll put my money where my mouth is) All numbers are 1 volt rms output. raptor 120 ohm load 106 ohm raptor 32 ohm load 32 ohm B52 (balanced) 120 ohm load 101 ohm B52 (balanced) 32 ohm load 30.6 ohm (this was a surprise as i thought it would be higher) singlepower white cathode follower with 5687's (can't keep track of model numbers) 120 ohm load 103 ohm 32 0hm load 31 ohm singlepower cathode follower with 6as7 (called the extreme) 120 ohm load 29 ohm 32 ohm load 18.2 ohm dynalo .3 ohm output impedance, 16 to 300 ohm load dynahi .13 ohm output impedance, 16 to 300 ohm load

Into 32 ohms the output impedance is 28.5 ohms Into 400 ohms the output impedance is 150 ohms

With a 120 ohm impedance headphone the small signal spice calculates the output impedance as 79.9 ohms.

- 6BZ7/6BQ7A are on the input in paralled and are setup in a 'proprietary circuit' that provides ~6db of gain and has the primary purpose of presenting 100ohms impedance to the rest of the circuit, regardless of the impedance of the source. That would be a differential amplifier with a gain of 6db and cathode follower. Hardly proprietary as this is exactly the same circuit that ray uses in the B52 front end. (subject to picture verification) Also 100 ohm output impedance of that tube as a cathode follower is just not possible. More like 2k. But still a fairly low impedance output for tubes. - 6CG7/6GU7 are in parallel and work in conjunction with the 27GB5/PL500 for the output. For each side of each channel 2 triode sections are in parallel. True - The 27GB5 are in a way setup to be the CCS for the 6CG7. An interesting way to describe an inverted cathode follower. - If you want to say one tube is on the output, it is the 27GB5. The 27GB5 certainly has the lowest impedance path to the headphones. Someone was asking me the output power of the amp recently... can't remember who. Anyways, he said that if you were to give it a wattage rating, it would be 6 watts. Into what impedance?? Certainly nothing in the range of 32 to 300 ohms. (but i'll go and calculate it) He also said that is not the best way to rate the power of a headphone amp since it tells you hardly anything about its ability to drive various headphones. He said a better way to put it is 98volts peak to peak. When I asked him about current, he said that it could put out 600mA at 100volts easily enough. Someone is smoking something! Besides which this is clearly irrevelant. I asked him about output impedance again and he gave me the same answer, 40ohms. UH maybe. small signal only into medium impedances. EDIT: He also said that the 27GB5s are in triode mode. TRUE.

You go and convince Jason to let me do this... Then i can probably knock it out in a weekend.

I'm joking of course except i'm not really joking. Duplicating jason's unit with point to point wiring done woo audio style would be god awful amounts of labor, and therefore out of line expense wise. So the thing i would really do is do a complete circuit board layout. All of the parts one one board of about 10 x 15 inches. With a group buy of boards something this size would likely be about $75 each. It would probably take me less time to layout the board, than to actually build one. A lot less time. Might even make it 2 dual mono boards, so you could build the thing as unbalanced only. Then just about anyone could stuff the parts and build the thing. Do it right with a real chassis, or a complete abortion like that wood thing that jason built. You could build it ray samuels style (tubes on one side, all the parts on the other) or justin wilson style (all the parts on one side of the board) Hell i can even layout the board singlepower style with all the tubes at 45 degree angles. For the record regardless of what has been previously said about jason's unit, there is absolutely nothing new in the design that has not been done hundreds of times before. Nothing new, nothing proprietary nothing out of the ordinary... Although the tube compliment is a bit unusual.

Maybe i should get into the business of upgrading/repairing singlepower and mcalister stuff. Sounds like a full time job to me A complete rebuild of jason's amp (same exact design, built correctly) is about $500 in parts plus about 30 hours of labor. At my labor rates that would be about $5750. Special discount for jason only.... $3000 Maybe mikhail might want to do that design in a dual box setup. Got to be >$9000 .....

spoilers One of the writers Aaron Douglas specifically said that 4 of the 5 final cylons would be revealed in the seaon finale. spoilers

After i get the final pictures from jason and then if he will let me i will post the schematic. Then some of you with the knowledge of whats going on will have a field day with the design...

They are all true!!! A friend of mine works in an appropriate place to get the episodes complete sans commercials. I saw the second part like 3 weeks ago... Hopefully next year i can get the same stuff the same way except in hi-def. Its far more intense to watch when its 43 minutes complete in one shot. Final episode is actually 4 minutes longer, so its 47 minutes.

Now that would be cheating NO??? Besides which the person that makes that "other" tube amp would argue it is completely different when it is actually 95% the same This is pretty much the last time i'm going to ask that particular person to send me the electrostatic portable transformer he has promised to send me for over 6 months now. After that a whole bunch of schematics and pictures may just have to appear

Jason was wrong. Before the final upgrade the 27gb5's were the active top current sources The 2 sections of each of the 6cg7 were in parallel and were the output gain stage tubes. The 6h30's were doing absolutely nothing usefull !!!!! (If you haven't figured it out by now, I have the schematic!) After the upgrade (i'm guessing here) The 2 sections of the 6bz7's are in parallel and 2 of them form an input stage differential amplifier. Same as the input stage of the B52. So you can supply balanced input, or unbalanced input. And then everything else is the same.

Open offer still stands. You send me a dozen of the same tubes. You label them in any way you want that will not rub off. I will randomly cryo half of them. I'll send them all back. You try and tell the difference. Your choice of 2 days at liquid nitrogen temperatures, (77 degrees kelvin) or if you really want, 2 days at liquid helium temperatures (4 degrees kelvin) No charge for the cryogens or use of the dewars. Students at northwestern university can verify that i actually did this. So far no one wants to take me up on the challenge...

The 6bz7's are most certainly in the input section, and not any part of the output section. There are large output tubes for the active current sources and other tubes with paralleled sections as the output amplification element. Don't remember the exact tube compliment at the moment. Similar in design to another tube amplifier well liked around these parts. Also remember that this is a balanced amplifier.

alrighty then, major spoilers below * The fleet realizes the Cylons are somehow following it to Earth. * Tigh talks to Six about it, but their conversation (thanks to Six

Nothing wrong with that. Nothing right with that either. Two boxes instead of one. Two sets of batteries instead of one. Two volume controls instead of one. Twice the physical size for absolutely no apparent gain. Have a happy new year.