nikongod

The amp is 3/4 built. Thanks for the help on the paints guys! The case is holding up well despite my best efforts to knock it about while I P2P the beast. The output caps scratched INSTANTLY while being mounted. Hopefully the last 2 parts arrive tomorrow or wednesday so I can finish this thing up. McMaster Carr has never failed me before. All of the paints I used said good for 200*f. Should be adequate for a tube amp case (I hope)

have a great birthday!

Not to fear: Dremel tool used extensively I actually managed to cut a hole for the IEC that dosnt look like cookie-monster went to town on my case, I consider this an accomplishment. The second coat went on with just enough time to set before it started to rain. The amp looks OK, although not exactly as "hammered" as I would have liked. Such is life.

Hello Board Im working on a shitty little amp that assuming the stars and plannets are in alignment will be at canjam. at the moment, not 1 part has been soldered but the casework is done and being painted.... Now that I have cursed my project by admitting that it exists: The case (a cheap "BUD box") that I am painting with hammer-tone paint, because it will (hopefully) mask some of my horrific screwups with the drill and could not ever look even close to as bad as a naked BUD box. I painted one corner of the top a little thicker than the rest, should I worry? Im going back for coat #2 in about 45 min... Thanks Ari

happy birthday !

hey Chris! Have a great Birthday

bought before the lock

60dB if your lucky, channel matching is totally conditional on how well the parts are hand-matched. LDR's sound great, but they are fiddly as hell and probably require better system matching than most people will do. Melos used hand-selected parts for their success. The photentiometer used a full-on automotive dome-light bulb for light source: it could be replaced with an LED sure, but it would still be drawing tons of current to get a high attenuation.

Happy Birthday!

Thanks guys

I just bought plane TIX.

Does anyone else have a spare bed, or need to go halves on a room? Thanks ari

Unless I read it wrong, 6dB is the gain on the high-impedance output. An 8:1 OPT with a center tapped secondary looks good crunching the numbers, also allows for the balanced outputs conveniently.

video>photos

I would be that this has a bunch more power than the GES. I would guess that there are plenty, when you look at your old gear QFT

My K1000 had the PCB "spontaneously removed" while recabling. If you would like to borrow them to compare you are welcome.

In ray's B52 mall-fi thread he posted that 2 B52's shipped, and 2 more were burning in (I assume sold) just over a month after the thread went up. On the other hand, he first showed a cased prototype of the B52 about 6 months before his intro thread at the first national meet. The guess that this is a rushed job does not sound so far-fetched.

happy happy birthday

agreed, ray does it as you say, and wrong. in an effort to use an SRPP circuit safely even with very high B+ this would certainly do: both triodes in 1 bottle for the "top halves" of 2 SRPP blocks with their own floating heater supply. both triodes in another bottle for the "bottom halves" of the 2 SRPPs sharing the heater for the gain/input tube. Its soooo stupid the way he (ray) does things. an additional heater supply and some more wires in the umbilical to do it right costs a bit, but I doubt thats really a significant cost for an amp that many people are speculating to cost more than $5000. After that its just a mater of NOT wiring things in the stupidest way possible, which he seems unable to do. he *could* have floated or "referenced" the heater on the craptor/B52 and been within safe limits of Vhk, but he chose to use an idiotmode switching supply and shared ground wires.

there is a way to do it without violating Vhk limits, but he has never done it right before. taking the (safe) assumoption that the output stage in this amp is called on to give some gain, the cathode of the "top" triode is going to be at FAR higher voltages than in the Craptor or "2 craptors back to back" (B52). the failboat is coming into port. Ray dosnt seem to be one to take any kind of advice or learn from the mistakes of others (even those he happily mocks himself) very well.

posted at the other site, and probably deleted. it is a paid thread. the 60's reference is that phase splitters to output balanced signals from single ended inputs have been available in preamps since at the latest the 60's, and probably earlier. My point really is: why not add a phase splitter to the B52? And really, why not build it that way from day 1? This raises the interesting question, considering that the B52 cant be guaranteed to output a balanced signal through the XLR's (It outputs unbalanced on XLR when an unbalanced input is selected) and that the A10 uses the phase splitter when a single ended input is selected, which Im assuming is switched in and out of the signal path as needed: What happens if a single ended signal is fed into an XLR input on the A10? Does the amp still output a balanced signal as required to drive an electrostatic headphone? Its a question that would have me ripping out my hair.

the output impedance will be pretty high (about 150 ohms at best, could easily be higher/worse if ray did the "right" things incorectly although he has experience from a similar output stage on the B52... why not use 5687 here too? ) and unless they are electrolytics, the output caps are probably too small. it may work for 2000 ohm headphones dont waste your time for anything else. increasing the size of the caps could make it do good things to beyers, which like higher output impedances. im curious if ray thought far enough ahead to use the preamp buffers (6sn7) to isolate the 12ax7 from the miller capacitances of the output tubes... bandwidth fail.

I think you have the 2 flip-flopped. The original purpose of the WCF was driving cables. its performance is independent of load as long as its not too low. SRPP on the other hand is totally load dependent. SRPP can come out of class-A without clipping audibly, and gets wrecked driving anything but its optimal load. the idea of driving a 32 or 300 ohm load off of the same SRPP output stage frightens me... If the ES-1 is what everyone says it is, it has a long-tail-pair input stage. the disadvantage of a LTP is you dont get as much gain, BUT you gain PSRR. A "Williamson style" concertina has more gain, but practically no PSRR... LTP can take a balanced input and claim "fully balanced", not that that really matters on head-fi as long as it has XLR in and out. A concertina is also somewhat sensative to how the outputs are loaded. The 2 plate outs from a LTP have equal Zo, where the "plate" and "cathode" outs on a concertina are not even close. miller capacatances or a resistive load screws the balance up. A real designer would rough his design out on paper taking a few iterations if necessary, P2P his prototype, tune 3 parts, and make 1 circuit board.

way to derail a thread, I thought we left head-fi to keep clear of this shit. there are plenty of threads here and there to muckrake in. Most wallwarts integrate the fuse into the transformer in various ways: saying "no fuse" is incorrect. what you meant to cut and paste was DR. gilmore's recommendation elsewhere that a fuse be placed in the DC rails to the actual audio stage. with alarmingly few exceptions, no wall wart is more likely than ANY manufacturered PS to cause a fire. The safety of rail fuses in an amp with bipolar supplies and whether they would even blow predictably in a class-A circuit and in a way which would prevent further damage to the speaker and amp is very questionable. in fact, you only need to look at the raptor to see a case where the B+ fuse blows somewhat randomly, although generally at NYC meets. fortunately, its a single supply amp with cap coupled outputs... on the other hand with a dual supply (+ and - voltages) when you blow one rail, the output goes to the live rail... good luck with that across your headphones. back to bashing RSA, its much more fun.

If you have the headphones for it, there is absolutely nothing wrong with those plugs, and the plugs are outstandingly awesome. on the other hand, if you dont have the HE90, you paid for an expensive socket that you cant use. for these people (and I think that people who DONT have the HE90 are going to be the majority of buyers for this amp, on the assumption that people who DO have the He90 already have gear they are happy with) something else would serve their needs better. putting the HE90 plug on is impressive because its a statement that this amp is good enough for them. sort of like running the R10 out of a portable amp.... I dont have a source for chassis mount EXP-950 connectors. I was referring simply to the headphones.