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Eddie Current Electra Electrostatic Amplifier - Page 29

post #421 of 429
Quote:
Originally Posted by Rico613 View Post
 

Greetings all ~

 

Anyone down for the next run?


I'm in the next run, I suppose. I sent in the order form a few months back..

post #422 of 429
Quote:
Originally Posted by clabbe View Post
 
Quote:
Originally Posted by Rico613 View Post
 

Greetings all ~

 

Anyone down for the next run?


I'm in the next run, I suppose. I sent in the order form a few months back..

That makes two of us.  We're on a roll !!  

post #423 of 429
Quote:
Originally Posted by Rico613 View Post
 
We're on a roll !!  

 

Did you go for any upgrades or customization? Went for the Jentzen caps myself.

post #424 of 429

Yes, Jensen caps.  Maybe another upgrade of XLR input sockets w/ silver shielded internal cable wire.  It will depend on how it sounds on another amp I'm getting - I won't know for a few weeks.  Let me know if you hear of other upgrades folks are doing.


Edited by Rico613 - 10/13/14 at 12:30pm
post #425 of 429

Sure thing

post #426 of 429

I received this note from Craig earlier in the week:

 

Quote:
We have been working on three different possible Electra MKII amps. The simplest upgrade is just adding a special circuit to match the driver tubes. Number two replaces the output tubes with 300B tubes, and lastly an SE version with single 300B and step up transformer. We want this to be better than the original, and it is just taking time. Pretty sure we will have it in production no later than spring quarter.
 

 

post #427 of 429

Sounds interesting.  What does the SE mean - Special Edition or Single Ended?

post #428 of 429


Single Ended

post #429 of 429
As an amateur amp builder, I've played with this topology off and on for several years. It's worth investigating.

A DHT/transformer based electrostatic amp will never match the technical parameters of a direct-coupled amp, but it can bring to the table a tonal presentation that at least some will find an appealing complement to the more modern balanced/direct-coupled designs.

I know nothing at all about this amp, but here are a few totally unsolicited and subjective suggestions based on my experience:

1) Keep the output transformer step-up as low as possible - preferably no more than 1:2 Secondary windings should be wound to minimise capacitance.

2) Run the 300B at a fairly high B+ and plate current. You want the 300B to stay well away from either cut-off or saturation regardless of the output demand. The more current you flow through the plate, the better your slew rate will be.

3) On the 300B, use "fixed bias" instead of the traditional cathode bias - you'll get a tighter more dynamic sound, especially in the bass. Use something, anything, besides the traditional bypass electrolytic capacitor on the cathodes of the first two stages.

4) Fully regulate the B+. I like a combination of solid state rectification and tube regulation. No electrolytic caps after the regulator. Regulate the bias supply as well.

5) Three stages, use lowest mu tubes possible, direct-coupling, and CCS plate loads. You can do it in two stages with high gm tubes like the 6C45pi, but it will sound harsh and reminiscent of solid state compared to something like a 27/6V6 combination.

6) Use high frequency AC for the 300B filament power supply.

My 2 cents from the peanut gallery.
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