[johnwmclean]

Not to mention getting a Sigma11's output close to 6.3V would be trial and error.

 

[nattonrice]

I think I am being blind here so if I am please feel free to yell at me...

I noticed in the NorCal meet photos someone has a recently completed EHHAII prototype.
I've searched around and I can't seem to find any information on this.
Is it a complete redesign or just a small modification?
Was/is there a thread that I seem to have searched right over?

 

[TheShaman]

I think EHHA II was initially planned to be a speaker amp. Was there a change of plans?

 

[johnwmclean]

Quote:

Originally Posted by nattonrice /img/forum/go_quote.gif I think I am being blind here so if I am please feel free to yell at me... I noticed in the NorCal meet photos someone has a recently completed EHHAII prototype. I've searched around and I can't seem to find any information on this. Is it a complete redesign or just a small modification? Was/is there a thread that I seem to have searched right over?

I’ve just searched http://www.head-fi.org/forums/f45/no...ssions-474994/ I can’t find any reference to an EHHAII, what was the post number?

 

[nattonrice]

LOL comprehension fail...

I meant the Seattle/Portland thread!
2nd post by dbel84.

 

[johnwmclean]

Thanks Tom!

 

[dBel84]

Quote:

Originally Posted by nattonrice /img/forum/go_quote.gif I think I am being blind here so if I am please feel free to yell at me...I noticed .. someone has a recently completed EHHAII prototype.

Sorry to be the tease, but this was a one off build which came about after several years of intermittent communication between AC and myself. This particular amp will not be released as DIY.

Quote:

Originally Posted by nattonrice /img/forum/go_quote.gif I've searched around and I can't seem to find any information on this. Is it a complete redesign or just a small modification?

There is no information available about the amp. It is to some level a complete redesign but retains the principles of the EHHA. In essence it runs high voltage rails, has a tube gain stage and remains DC coupled.


Quote:

Originally Posted by TheShaman /img/forum/go_quote.gif I think EHHA II was initially planned to be a speaker amp. Was there a change of plans?

The DIY EHHA II was originally pegged as a 4 layer PCB with a very small footprint and purely a speaker amp.

..dB

 

[sachu]

The EHHA-2 is sure to make waves when and if it does get released.

It has closed the gap right up to the stacker 2 and even surpasses it in some areas. I am finally glad to say the EHHA(albeit version 2) is back at the top of my list of headphone amps. I didn't get a good chance to listen to it however so look forward to having a coupleof mini meets at my place comparing all the best of the Cavalli amps side by side. TO pick a clear winner would be tough..the two have their own individual sound signatures which is quite easy to notice.

 

[aloksatoor]

should be simple enuff by buying a handful of 6.3V D5 zeners and testing them out. And would not need to install the R10 resistor which makes it simpler.

Quote:

Originally Posted by johnwmclean /img/forum/go_quote.gif Not to mention getting a Sigma11's output close to 6.3V would be trial and error.

 

[Symphoenix]

Quote:

Originally Posted by sachu /img/forum/go_quote.gif Very cool pics Symphoenix...i guess you staying up all night listnening to it summed up your thoughts on its sound quality Btw, have you tried the 6GM8s at all in the amp as against the 6H30? Would love to know your opinion on it.

Thanks man. Yeah great sound quality : rich bass, very good separation of the instuments, highs aren't agressive (important for my taste).
I haven't tried the 6GM8s yet but intend to very soon. I'll keep you informed

 

[nattonrice]

Quote:

Originally Posted by dBel84 /img/forum/go_quote.gif Sorry to be the tease, but this was a one off build which came about after several years of intermittent communication between AC and myself. This particular amp will not be released as DIY.

Oh that's a shame~ it looked really wicked.

Perhaps sometime in the future a variant may be released under the same name

 

[sachu]

Quote:

Originally Posted by nattonrice /img/forum/go_quote.gif Perhaps sometime in the future a variant may be released under the same name

Sure..one can dream

Back to the EHHA, I was wondering what kind of circuit adjustments need to be made to run the tube hotter. WIth only 1.5mA on the plates and 30 volts we are barely dissipating anything on the plates. I was wondering if we could increase the plate current to about 7.5mA. We should still be well within dissipation limits for the 6GM8.

This would mean changing R3, R4 and then the current mirror appropriately..

Any changes in the VAS? any other changes?

 

[adamus]

i get slightly lost, but there is a css in the tail.

two diode drops -vbe = 0.7v ish

0.7v / 200 = 3.5ma
so just over 1.5ma per triode

so r9 is setting the tail current.

 

[pidesd]

can i use 2 6gm8 and 2 6n27p in a balanced config.? to they behave they same way?

@adamus,

thanks for the link about the shunt reg on diyaudio

 

[jjazzyj]

This is my work on the S22 power supply so far. The transformer is sized to be able to drive speakers and although it is a tight fit, I will be able to add an additional S22 board. The umbilical cable will also be able to accommodate a separate 30GND-30 run to the second set of EHHA boards. I kept the umbilical extremely short for obvious reasons. I hate acrylic, but unfortunately no one sells translucent white polycarbonate. The bottom is 1/4" polycarbonate. That way you will see a nice blue glow from the bottom of the power supply as well as the translucent plastic giving you a nice warmth from the LED as well. Next is drilling and tapping the polycarbonate for the standoffs/xfmr mounting. AC GND will be tied to the aluminum frame. The Balanced EHHA amp will be in an identical chassis. And by doing this I can build a B22 and use the same power supply if I want

The umbilical cable:

This project was certainly a little bit over my head. I can almost see the light at the end of the tunnel. Once I get the power supply assembled and tested I'll feel a little better.