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 !

 

 

 

From what I have heard from the dark side, the new tubes do not last as long as the NOS tubes.

NOS tubes like Mullard is hard to find especially we need eight of them.

 

Psvane is more easy to find but sometime quality is not well: missing the bar.

 

 

Hi, anyone have a spare set of boards for the Megatron?

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Edited November 11, 201510 yr by JoaMat

Fuck yes, my Edcor order ifor the Megatron filaments is coming in

 

They don't fuck around when they say "6 weeks lead time"

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

Hehe.    Perhaps scrap the terminal blocks and put the transformers at an angle? 

You could always mount the transformers on the sides..... inside sides that is.. 

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

There is a drawing of them in his ebay listings. 

That looks very nice nopants. Look forward to see your completed built. And I guarantee you will be happy with the sound

Which transformers are those?

Edcor for the filaments, a little large but should be able to handle any EL34. There's so much work involved in assembly I might not end up selling it haha, definitely worth more than its cost in parts

That's one of the reasons why I'm hesitant to build more Megatron's.  I did design a new PCB for it (hello huge caps plus a bunch of other changes) and get some umbilical cable but it is such a complex amp. 

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

The board is actually much smaller.... 

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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Edited November 11, 201510 yr by JoaMat

Yeah I just try to buy the I/O capacity I need since the cost is exponential when it comes to proper connectors

 

Did you bother trying to compare AC and Dc heating? Sonically that is

The easiest way would be to wire the tubes for 24V and use a LM7824. 

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?

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Edited November 11, 201510 yr by JoaMat

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. 

Ask Victor Chew. I know he was looking into using DC for the front tubes and may have already done it

found that the antek fits:

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