*New Build Thread* 2nd Gen Hybrid 50w footswitchable FET

[amplifiednation]

NOS upgrade!!

Built a new board with Pihers and Electra resistors, also NOS Sprague orange/brown drops.

Pihers for the mid and PAB swithes, power grids, I'll probably go with some nice CC for the preamp grids.

Also upgraded all but one pot with Clarostats!

Any thoughts on the 2000pF cap? It seems very high compared to the 510pf in#40....but there's no mid boost in that amp?

Thoughts???

[dcribbs1412]

NOS upgrade!!

Built a new board with Pihers and Electra resistors, also NOS Sprague orange/brown drops.

Pihers for the mid and PAB swithes, power grids, I'll probably go with some nice CC for the preamp grids.

Also upgraded all but one pot with Clarostats!

Any thoughts on the 2000pF cap? It seems very high compared to the 510pf in#40....but there's no mid boost in that amp?

Thoughts???

Looks great Taylor
My thoughts are put that monster together and Rock It!!!
Seriously...any thing can be changed later...build it the way you think and change the cap(s) later if needed.
I'm interested in how it feels/sounds with the NOS stuff...do you have another D-style with non-NOS parts?

Darin

[amplifiednation]

Oh man, if I had more time during the day this would be rocking already!! I've got some shielded runs to do and might get the board dropped in today...we'll see. I got cabs to build!

I've got a 102 with all new production parts, except with old iron and what used to be NOS glass...I'll have old iron and NOS glass in this too, so hopefully there will be a comparison that I can capture on some form of recording. I'll take any chance to video tape myself... haha

[amplifiednation]

Finished my shielded runs and other "under board" wiring to keep it neat...then i dropped the board in and wired it up.

I hope this thread is as helpful to some as my #102 thread was reported to be...

These pics would have been helpful to me during my first D-build...so i hope someone can get something out of them!!

I've included a couple "under board" and "below board" wiring for those who haven't conquered these builds before. I'm no expert, but this is how I think the wires should be run.

Maybe someone will chime in if I have it wrong.

I've also included my progress pics...which make me happy!!

i gotta get to bed...

rock n roll.

T

[boldaslove6789]

The NOS parts will be totally worth it!

[dcribbs1412]

Looks great Taylor
interesting that you wait to run the power to the preamp
where did you pickup the Piher's...1/2 watt?

Darin

[amplifiednation]

Well Darin,
The Piher fairy sent me them...I got them in a cab trade...so I don't really have a source for them. They were pricey though!!

I figured I would do the power runs after. I haven't decided what wire to use, not this AWG hook up wire though, it's only rated for 300V

I'm pretty much at a dead spot until i get my PT, choke, and relay transformer this week. then it should be go time. I think i'm gonna grab a Mojo/Hayboer Bassman PT. Can really beat the price.

I'm skipping the FET for now. I'll put it in later. I want to make sure i get it biased right before putting it in the amp and can't wrap my head around Martins' method yet, but I will!!

[talbany]

Taylor
While your waiting see if you can find some NOS for the grids..you can even use CC there wold be better than what's in there now.. Then everything in the signal path would be covered..

Tony

[amplifiednation]

Thanks Tony!! I've got some 1W CC coming for those grids upon Davids suggestion, so I'll give those a try. I have some nicer CF coming too in case I don't like the CC

[martin manning]

Looking good, Taylor! Just for you, there is now a .pdf in the D Files section that describes the FET-bias-with-a-battery technique. You can have it done before you get those parts you're waiting on.

[aflynt]

I just ordered some 1/2 w Pihers from whazzgroover on Ebay. They should arrive in a month or so. I'll let you know how it works out. Would it be possible to use 1/2 watt on the preamp grids?

-Aaron

[boldaslove6789]

I just ordered some 1/2 w Pihers from whazzgroover on Ebay. They should arrive in a month or so. I'll let you know how it works out. Would it be possible to use 1/2 watt on the preamp grids?

-Aaron

Yeah .5w is fine for the grids, although 1w is prefered.

[Dr d]

Really nice looking build! Having little knowledge of NOS parts, Im assuming the plate resistors are electras? Do you mind me asking what make the greenish looking bypass resistors are on the cathodes?

[ToneMerc]

Im assuming the plate resistors are electras? Do you mind me asking what make the greenish looking bypass resistors are on the cathodes?

No, those plates are Mepco/Electra and the cathodes have the Electra. To be 100% Dumble correct the resistors should be all Electra. I have never seen that M/E in any Dumbles. When Electra took over Mepco they carried over the MFxC designation, then it was dropped that a few years later.
There's a physical and chemical difference between the two types, but I can't say if there's a tangible difference in audio beween them. Although #183 has a 22K Electra on V1a grid, HAD may have just used what he had on hand verses any type of preference.

Here's a couple of my builds with Electra and Piher resistors as well.

TM

[CHIP]

I've used the mepco/elektra 100k resistors in place of new production Dale RN65.
While I can't get any"correct" Elektra's, I will tell you this , the "non Dumble correct", mepco/Elektra sound better than the new production RN65's.
Finding NOS parts for these amps is a very frustrating journey. I got some values over the past year, but not like some of these guys around here. So if you see em snatch em up fast or you'll be outta luck pal.