Megatron Electrostatic Headphone Amplifier

[Peleus]

Thank you all! 

 

To keep going on my megatone work! 

[nopants]

I am sick and tired of all you guys and your nice casework so it's time I shit on the thread:

I'm glad this isn't headfi so I don't have to preface how stupid this is on multiple levels. I'm sad it doesn't fit in baby's first audio rack that I just purchased, but maybe it's better that I can't leave it there.

this amplifier has certainly changed my mind about ac coupling, I'm so impressed.

[spritzer]

Nothing wrong with AC coupling.... 

[kevin gilmore]

its dc coupled where it counts. the ac coupled part is very high and constant impedance.

nothing wrong with open architecture.

as long as there are no kids or pets around

Edited March 9, 2014 by kevin gilmore

[nopants]

I certainly see that's true now, I just haven't liked choosing what I consider to be subjective components like coupling/bypass caps. if I revisit this I will try the Russian teflons and Mundorf supremes and check things out. I might get more mileage out of swapping tubes though

for other people interested in building the megatron there is a guy on diyaudio selling 1967s. I think these should work as a 1968 substitution ( just an exposed tab), goes by Craig buckingham iirc

[Grand Enigma]

Surprised Mikhail didn't just ship his amps like that.

Here is your point to point ball of wires and caps

[nopants]

I don't think single power would have sprung for old electrocompaniet cases, I only do shitty casing of the highest quality

[n3rdling]

What timed switch did you guys use for the HV supply?  

[nopants]

I'm using two switches, lazy

[mypasswordis]

There are tons of 555 based relay circuits on ebay and wherever else, pretty sure I'm going to use one of those. The T2 555 timer is configured for ~ 60 second delay but I can't be bothered to wait that long :/

[niner]

Can someone double check it for me: is there an error with the ".2" PCB?  I found one leg of the 0.1uF bypass cap is not grounded (or connected to anything) on my PCB.  Please see the attached image, circled in green.

 

[spritzer]

Yup, that one should be grounded. 

[kevin gilmore]

fixed in the next production run.

[niner]

Thanks for the confirmation.

[Milosz]

fixed in the next production run.

 

 

...is there going to be a run of PCB's for Megatron?

 

[spritzer]

Anybody can do a board run but don't expect one from Kevin and I. 

[n3rdling]

Anybody local have 2x LT1021-10 I can buy ASAP?  I'm done populating my Megatron and KGSSHV PSU boards and wanted to take this amp to the meet on Sat but I forgot to order that part.    I don't think ordering from digikey will reach me in time unless I pay $64 to overnight the 8oz package.

[GeorgeP]

My experience with digikey has been that I receive the order the day after I place it - without upgrading shipping. No guarantees obviously...

[blubliss]

I can check, email me.

[Milosz]

Anybody can do a board run but don't expect one from Kevin and I. 

 

 

I see so when Kevin mentioned "next board run"  it was HIS board run-  not a general run of boards  that was being organized by someone.

[luvdunhill]

No, it was the next run when someone other than Kevin or Birgir did one.

[spritzer]

Bingo

[kevin gilmore]

One of the members of our work team retired early. And I completely understand why.

So if I had any free time left, which I already did not, I certainly do not now. Plus

if I use my preferred vendor I pay Illinois sales tax. Its stupid for me to have boards

made.

[spritzer]

Same problem here but add on far higher taxes. 

[mypasswordis]

Hope things get slightly less hectic for you guys. Also sorry for continuing to flog a dead horse, but if we can't find legit 1968s (unless we feel like paying $9 at Bdent) can we stack 1486/STN9360s or 1156s? I assume the Ebay 1968s are fake?