[purrin]

I figured I should throw this up here since talk of the Electra will probably permeate through various other threads.
 

 
4x6SN7, 4x6L6
 
This will be at T.H.E. SHOW in Newport Beach this coming weekend.

 

[cacatalysis]

What are the tubes?  Is there going to be a SE version?

 

[kiertijai]

There should be single ended and balanced input, but what is the  "O" on the input selection
What is the function of two green knobs on the side?

 

[kiertijai]

The Electra deals with the complexities of driving capacitive loads with high slew rate. The amplifier topology uses all vacuum tubes, has a gain of 56 dB
 
      Correct me if I am wrong,  The tubes used are 6l6GC's quad (and KT66) and 6SN7's quad
      I hope I can use KT77 or EL34 because I have several of those, but I don't think this is the case.
      Please provide us info. with the SR009?

 

[Radio_head]

kiertijai you're thinking of the SE version which Craig is working on now.  The Electra that Craig (or Andy) has ready for the show uses the tube Purrin mentioned.  This is the one that will be at the show.  Looks almost like a production version already besides for the transformer cover.

 

[Elysian]

Looking forward to reading more about this amp.  Has any dimensions and weight info been released yet?

 

[Radio_head]

ZDT chassis so dimensions should be about the same.

 

[spritzer]

Ehh, what's up with those bias voltages?  Certainly not the right ones and does the warranty of the amp cover blown up normal bias headphones? 

 

[Radio_head]

Craig said he's just fooling around with the bias at this point.  It will be changed before production.
 
Edit - also, I assume he meant 230 (?) for normal bias and 580 for pro.

 

[purrin]

I assume the 520 is for the Senns which take 500/540 for HE60/HE90?

 

[Radio_head]

Here's another image from his site:
 

 
Looks like 6 and 5 pin so normal and pro makes sense.
 
Edit - the LL has the 2nd jack available as either 500 or 540, depending on which of the two you have.  If 520 would work on both, you would think other amps would also operate at that point.  
 
Knowing Head-Fi these days, I'd expect the production version to have "230, 500, 580, and Cognitive."

 

[spritzer]

The bias implementation isn't something to be taken lightly as the incorrect setup will burn up the diaphragm or make the drivers much more prone to arcing.  That's why nobody in their right mind would build one of Ciuffoli's designs without serious modifications for instance.  Running normal bias at 330V cuts their max voltage swing way down from 460Vpp so one wrong move with the volume control and they can suffer permanent damage. This is even more of a concern with the HE90 since the margin for error is far lower and new drivers are only about 6K$ for the pair... 

 

[purrin]

I'll be sure to tell Craig to make it more idiot proof. After all, that guy at 6Moons did almost blow up his speakers because he thought the RCA loop outs were pre-outs on the BA. Supposedly a few folks burned out their 4V DHTs on the BA because they forgot to change the variable voltage power supply from 5V to 4V.

 

[Mr.Sneis]

Quote:

I'll be sure to tell Craig to make it more idiot proof. After all, that guy at 6Moons did almost blow up his speakers because he thought the RCA loop outs were pre-outs on the BA. Supposedly a few folks burned out their 4V DHTs on the BA because they forgot to change the variable voltage power supply from 5V to 4V.

Wow I don't get how you can mix those things up!
 
Any word on cost?

 

[Radio_head]

Aiming for $2800, should be less than 3K.  SE maybe 3.2K.