justin

here is some detail on this amp: - Black Gate capacitors - No XLR input/switch - Single GoldPt stepped attenuator

it might just be showing the voltage

It must feel great to have lost all that weight Nobody else thought to search for a vince vaughn pregnancy?

Originally I used 4-mil double stick tape to secure the battery, but my latest shipment of batteries aren't as flat on the bottom so that wasn't working out. I used some hot glue and it didn't hold on a few amps in shipment. I've gone back to double sided tape only much thicker this time.

Congrats nate/vince! Your next DIY projecT: hang objects with jena labs wire. black gates, output transformers, and other things babies love. hydrocity will have the drawing plans soon

there's no reason to use it as a pre-amp. it's the same design as the dynalo, but with higher power output transistors, and cascoded input stage which is required due to the 60V of power supply. just more noise and a slightly more complex design.

I think this is partly because the free-for-all dynahi building once boards were available drove the price down to practically nothing, killing the value of the design, and with it the opportunity to offer properly built units at realistic prices

Not really, but maybe. It's for soldering underwater

You'd have a much lower damping factor resulting in the amp having less control over the headphone, most noticeable in the bass. You may prefer this, as many OTL tube amps have practically no damping factor and the headphones are free to resonate.

Never tried one. But it's really, really hard to make an electrostatic amp and sell it for less than $1k. And that would be the cheapest design possible but still with decent parts in a nice looking case. It's the custom high voltage power supply and the low quantities that kill it.

It's not possible to beat the Stax SRM-313 for the price

oh and most importantly, you need at least 3 filament supplies (input 6H30, 2nd 6H30, 6S4As can share one)

I tried, but failed, to build this a few years ago. I didn't have as much test equipment as I do now or as much experience, but what I found was i might have around 40Vrms audio signal at the cathodes of the 2nd stage tubes. However, each 0A2 tube was losing about 10Vrms audio, so there was almost nothing left for the 6S4A to amplify. I had RCA 0A2 tubes but never tried any others. You may want to try Russian equivalents that may be newer. Also, you can try neon lamps or zener diodes, i never tried either of those to see if it solved my problem. Also, at least for testing, you can capacitor couple the output of the 2nd stage but by removing the 0A2s you'll have to change the circuit so the voltage on the 6H30 isn't exceeded and add a grid resistor for the 6S4A The only thing I see incomplete in the schematic is that power ratings aren't given for the resistors but if you can't calculate these you'll have a lot more problems later. There's also no way to adjust DC voltages, you may want to replace the 1.2K resistor with a resistor+pot in series, to adjust points A and B to be 0VDC, and replace the 600 ohm degeneration resistors with resistors + a pot for a +/- DC offset adjustment. You should also split the 300K resistors into 3x 100K or 2x 150K or at least make sure the single 300K is rated for high voltage

it's hard to predict this one since it's almost always going to come with a pair of headphones and some of the older HE90 i've seen look much more worn than the ones that came from Meier 2 years ago. If you did find the amp by itself i think you could pay anywhere from 3 to 6k for it

Hmm i've had this question multiple times lately. You can still get the WPI connector from Arrow

i got an 80/100, but this isn't NYC. several UVA restaurants/bars are 1/4 mile away

I don't know all the rules but unless your vacuum cleaner is made of metal it probably doesn't have to have the earth wire

Just use 2 resistors as a voltage divider (attenuator). A lot of amps have similar things in the signal path in addition to the volume control, before and/or after the volume control. You're not going to get more than 0.000001% distortion, just pick appropriate value resistors based on the source's output impedance, not too low and not too high

I've been reading a lot of this stuff, and I think these issues are underrated. The problem is unless you design the entire audio system yourself thinking about ground loops, and have control over the power source, there's not a lot you can do about it. The typical high-end audio system is a combination of equipment made to consumer standards, some kind of pseudo pro stuff, something untested & improperly made, and maybe throw in a computer or cable TV line somewhere

unless it is a plitron, then you have tell them

Nope...i think it's been at least 2 years since I did

it is a balanced amp so i think Quad Dual Monos is more appropriate

Since it was also a movie title, shouldn't it be " The 'Blue Hawaii' "? Or on a front panel of an amp would it be "The Blue Hawaii". Is this boomana's area of expertise?

- New power supply design in a separate box - New active current sources for the output tubes - Some changes in parts values (Linear Systems LSK389 instead of the discontinued Toshiba 2SK389), one BJT transistor changed There's a huge and constantly growing list of other improvements of the type that don't appear on the schematic

I wonder if anyone will actually build it with a 50V cap for C3?