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Megatron Electrostatic Headphone Amplifier


kevin gilmore

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for anyone who has problems to select tube: DO NOT USE RUBBISH TUBE....

 

1.Nameless China made el34 and 12axu7

 

2.Russia EH EL34 Mullard and JJ 12axu7(ECC8XX)

 

3.Psvane EL34PH and 12axu7

 

comparing three different el34/6ca7 and 12ax(u)7

 

sound is big difference with different tubes.

 

Psvane is so awesome,i love it ! :dance:

 

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  • 4 weeks later...
  • 2 weeks later...

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what I learned today

just because birgir said he can fit something into x chassis doesn't mean I can fit something into x chassis

maybe the one nice thing about the megatron is that if you manage to get it working it almost has to look impressive

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yeah I was already in the process of mounting them on the side, the blank side panels were just to measure clearances when I didn't have the transformers. unfortunately not enough space to mount all of them to the side so the shared filaments will be mounted behind the front plate

speaking of front plate does anyone have a drawing of justin's stax jacks? I wanted something that could be used as a stencil. it would enable me to blind tap the faceplate by hand

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I found two cases (after purchasing my parts) out there that will fit probably all of the parts into one chassis with reasonable ease. It's still an off the shelf affair:

 

http://www.ebay.com/itm/FULL-aluminum-large-size-chassis-amplifier-case-DIY-enclosure-BOX-438-182-390mm-/261853624433?pt=LH_DefaultDomain_0&hash=item3cf7b13871

 

http://www.ebay.com/itm/FULL-aluminum-amplifier-chassis-enclosure-post-amp-case-enclosure-330-240-470-mm-/251921743239?pt=LH_DefaultDomain_0&hash=item3aa7b4bd87

 

I don't know how much larger your board got but this is probably big enough to do either PCB or P2P for the amplifier section. The heatsink in the back seems like a good choice for offboarding the power supply/supplies. Pretty sure the surface area is big enough to not have to resort to putting components on the bottom face, and the side panels seem reasonably thick. Bit on the ugly side, maybe they'll do it up in black as an option

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Anyone besides Birgir opt for DC filaments in the front end? I'm having a bit of trouble fitting that last transformer into the case and one of the options is to upgrade from 7 to 8 pins on the umbilical, and route 6V.3@~1.8A or [email protected]. I can also route the filaments via AC if I upgrade to 9 pins.

 

Wondering what you guys were using for regulators. Just sold a pair of Millett regulators to Frank, so I'm in the market

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I'll look into that as an option as well, does that require messing with some of filament traces on the board?

 

Also I have some CT's on the edcor transformers. I assume I can ground these everywhere except the floating filaments?

 

The filament for the front end is 6VAC with one leg grounded so CT can't be used there.  I wouldn't connect the CT on any of the other ones either.  That would end very badly... 

 

If you want to run at either 12V or 24V then you have to mess with the traces and the heater center tap.  12V is with the center tap floating and one leg of the heater grounded.  24V is the same except it has two heater elements wired in series. 

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found that the antek fits:

4dd38f7512706594bf3b5217df474d51.jpg

I'm racking my brain figuring out how to mount an alpha pot, I'm not 100% sure an rk27 will line up with the hole I made. it's a last resort though, use a new faceplate to accommodate the bound mount pot.

did some work on the psu as well, pretty trivial compared to the amplifier

bc4bbac3ef136d8c363d998559af0b04.jpg

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