dsavitsk

I have a scsi raid card and 3 scsi HDDs that are yours for the shipping if you want them. Otherwise, I'd buy a used thinkpad X61 and call it a day

Pffft. Real DIYers have MAPP gas torches ...

Some people argue that the perceived big sound of DHTs is basically reverb from the DH filaments. Any correlation between people who like the LCD2 and people who like 300b/2a3/307a/etc headphone amps?

I took a differential geometry class once, and I'm pretty sure it was all made up as the professor went along. all the way with gauss bonnet

That sounds like no fun at all. Best wishes for a speedy recovery.

No, not dead, just delayed. We have, in hand, what we hope to be the final revision of the PCB -- it is now 14" long. We are waiting on a prototype of the final case, which we thought would have arrived already. Probably in the next week -- other cases ordered at the same time from the same vendor are in transit, so this one can't be far behind. There were only two of the final prototype boards made. Tom is building one, but if anyone (HiGHFLYiN9) wants to do the other, I also have a set of the transformers and a blank 14" case. Whomever wants it can have it for cost.

Thanks Marc -- I'd appreciate it.

Thanks everyone! I spent most of my birthday driving from Ithaca to Chicago. Didnt quite make it, so I am spending the rest in a dumpy hotel in fremont Indiana home tomorrow ...

Maybe they mean Australian winter

Does anyone have a 1uF, 250V or higher electrolytic cap (on 2.5mm pins)?

I don't get the appeal -- I don't listen to headphones because I can't afford speakers, I listen to them because I like them better. Why would I want to ruin that experience?

There is this weird belief at HF that a 10W amp is really different from a 1W amp when putting out 1/10W. I heard a pair of these at the NYC meet, and they sounded like PA speakers in a gym. All resonance and awful. Maybe the felt had fallen out, or maybe the amp was a bad match, or maybe I was just not in the mood, but it was not good. Very odd. I am itching to hear another pair now that are known good on a system I am familiar with as something definitely felt wrong.

The auditory neuroscience community uses Etymotic, if that means anything.

The Wolfson WM8741 DAC chips have a voltage output of 2Vrms with a full scale digital signal. 2Vrms is about 5.7Vp-p. The DAC chips can only handle a PS of up to 5.5V, and are really recommended to run at 5V (actually, they can take 7V, but Wolfson will tell you never to actually run them over 5.5V). Anyhow, suffice it to say that the chips clip. They have an option to cut the signal by 2dB which results in 4.5Vp-p (~1.59Vrms) which they do just fine with. Different headphones perform differently with different amplifiers. Full stop. The notion that one perfect amp can perfectly drive everything is simply nonsense. For instance, with a traditional voltage amplifier, I think Grados do best with 10-15 ohms of Zout, balanced or SE. With an amp with near 0 Zout, they sound terrible. And this is a large part of the reason for the "Grados work well with tubes" myth in that tube amps tend to have a non-0 Zout. However, I also think they really shine with a Gm amp with a Zout in the hundreds, if not thousands, of ohms. Those same amps may not do well on other brands/designs. So, finding just the right synergistic combo would be a lot easier if we started matching gear in reasonable ways, rather than treating every headphone as a black box to be driven the same as every other one. Nobody expects a 45 amp to drive their B&W 801's, and nobody expects their Krell monstrosity to drive Loethers, so why do we expect this in the headphone world? Anyhow, this is a great thread so far

I could use one of his his XO's @ 24.576

Basically, the only step left is telling the case manufacturer to go ahead and start. That should happen this week ... I think.

Good to hear you solved this. And, good to know that we need to check each of these transformers individually before sending them out.

Too many hand matched parts/different configurations to make that work. Also, I am concerned that stencils and/or ovens will leave filled through holes. So, the directional hot air seems like a decent solution. Pace is definitely too expensive, but I think I'll give one of the less expensive ones a try and see what happens. I took rework to suggest that nobody would solder a whole PCB full of SMD parts with one, but that it was the best way to do a few. I guess I'll find out.

Happy Birthday!

Does anybody here have any experience with hot air rework station soldering? Anything to look for or avoid? And, how does this compare to flood and suck or toaster oven soldering? I was looking at this one as being in my price range and having generally good Amazon reviews.

Assuming there is no DC across the primaries, you probably just want some standard 600 ohm line level transformers. There are lots of these available for not too much money. My favorites are probably the Cinemag CMOQ-4H which are quad filar on 80% Ni cores. Only issue is that ordering from Cinemag takes some time (I have a couple dozen around, though made to my specs -- send me an email). The Lundahl LL1527 is a good reasonably inexpensive option (it dispenses with some of the features that make Lundahls expensive and which you don't need here), though if the output level is high the cores might be too small. Jensen has a dizzying array of choices, but the Cinemags are probably better and cost less. Probably not a bad idea to pick up some Edcors which can be had for $10 each. Hammond also makes some like the 145E (available at Mouser) which look pretty crappy, but might be OK to play around with. Oh, and eBay is a good source for vintage stuff, something like an Altec 15356, though frankly I don't get the obsession with vintage transformers -- I think new is good here due to improvements in core material.

Transformers vibrate, so anything loose that could rattle due to that vibration could be causing your noise.

Happy Birthday!

Just to keep everyone in the loop, we are waiting on a vendor. But, I think we are getting close ...

One other note -- fwiw, the 80dB down distortion peak in those graphs is ~0.01%, Adding in -95dB brings it to 0.01016%