[runeight]

It's ok for the bias voltages to be slightly off. .1V is ok.

 

[funch]

Thanks. First listening impressions are very impressive, and a little
disturbing. A little disturbing because this thing is sounding almost as
good as my Bijou at about half the cost. Of course, my Bijou is crammed
full of Auricaps, DACT SA, etc., so I guess I shouldn't snivel too much.

 

[sachu]

Quote:

Originally Posted by funch /img/forum/go_quote.gif Thanks. First listening impressions are very impressive, and a little disturbing. A little disturbing because this thing is sounding almost as good as my Bijou at about half the cost. Of course, my Bijou is crammed full of Auricaps, DACT SA, etc., so I guess I shouldn't snivel too much.

It should easily eclipse the Bijou..for me it does..I guess it is a preference of hybrid over full tube topology.

I find it disturbing that not many people even know about an EHHA, let alone looked at the EHHA design on Alex's website.

What resistors do you have at R22, R23 and R13?

Look forward to your in depth impressions.

 

[HeadphoneAddict]

Quote:

Originally Posted by sachu /img/forum/go_quote.gif It should easily eclipse the Bijou..for me it does..I guess it is a preference of hybrid over full tube topology. I find it disturbing that not many people even know about an EHHA, let alone looked at the EHHA design on Alex's website. What resistors do you have at R22, R23 and R13? Look forward to your in depth impressions.

If I had known about the EHHA and how good a balanced one sounds, I would have had one a long time ago and maybe not some of the other amps that I have. I prefer wiatrob's EHHA to my Square Wave XL or ALO Amphora. It probably sits somewhere between my maxed WA6 and my EC ZDT.

 

[sachu]

Quote:

Originally Posted by HeadphoneAddict /img/forum/go_quote.gif If I had known about the EHHA and how good a balanced one sounds, I would have had one a long time ago and maybe not some of the other amps that I have. I prefer wiatrob's EHHA to my Square Wave XL or ALO Amphora. It probably sits somewhere between my maxed WA6 and my EC ZDT.

Well you can take the EHHA further..Bill i believe had his telefunken 6GM8 tubes in them...stick a set of 6H30P-DRs in the EHHA and it gives you a whole another level, noticeable improvement in the bass with a slight roll off in the treble. Then when you start playing with the feedback resistors you can change the tonality of the amp altogether..They act almost like a balance control on the amp albeit a finer adjusting one.

 

[smeggy]

yes, EHHA with 6h30 or even the cheapo 6n6p is a real treat as sachu says. Tweak the feedback resistors (I removed mine) and it's a pretty thunderous amp. Very clean and clear. Those tubes do need a good amount of current to run the heaters so make sure your supply can handle it. Mine currently runs AC heater directly off the transfo but I do have a nice DC supply to go in it.

 

[johnwmclean]

Quote:

Originally Posted by smeggy /img/forum/go_quote.gif but I do have a nice DC supply to go in it.

What DC supply you adding smeggy?

 

[smeggy]

it's one of a pair of supplies I bought from ebay. No idea if any more would be available but they have multiple taps with different adjustable voltages and ranges from 1.5 - 10A. Big hairy monsters..

Imageshack - dsc8294t

 

[sachu]

Quote:

Originally Posted by smeggy /img/forum/go_quote.gif Big hairy monsters..

So much like you..i see the attraction now for you to use those insanely big boards

 

[smeggy]

It's probably a compensation issue

heh

 

[funch]

Quote:

Originally Posted by sachu /img/forum/go_quote.gif It should easily eclipse the Bijou..for me it does..I guess it is a preference of hybrid over full tube topology. I find it disturbing that not many people even know about an EHHA, let alone looked at the EHHA design on Alex's website. What resistors do you have at R22, R23 and R13? Look forward to your in depth impressions.

Nothing in 22/23, 1.21K in 13.

 

[jjazzyj]

In a previous post in this thread it was mentioned that R13 needed to be changed to 10k in order for the amp to run speakers. Would that not reduce the CL gain? Am I wrong in assuming we want more gain with speakers or is that incorrect? I am going to be running a balanced EHHA with speakers.

 

[runeight]

I hope I didn't say that.

R13 can stay the same for lightweight speaker duty.

With 1k2 an SE amp should reach about 18W (4R) with a little over 1V peak at is input.

With a balanced amp you'll have twice the effective gain.

 

[MrSlim]

Quote:

Originally Posted by smeggy /img/forum/go_quote.gif it's one of a pair of supplies I bought from ebay. No idea if any more would be available but they have multiple taps with different adjustable voltages and ranges from 1.5 - 10A. Big hairy monsters.. Imageshack - dsc8294t

Smeggy, with the kind of crazyness you get into, you should probably be dead...

 

[jjazzyj]

Quote:

Originally Posted by smeggy /img/forum/go_quote.gif it's one of a pair of supplies I bought from ebay. No idea if any more would be available but they have multiple taps with different adjustable voltages and ranges from 1.5 - 10A. Big hairy monsters.. Imageshack - dsc8294t

I'm using a custom transformer that has a 12V 5A winding on it. After that I'm following the circuit Alex has on the EHHA website with a 5A LDO (LD1084V) I'm probably going to try and get 12V and run the heaters in series. I'm aiming for slightly under 6.3V to hopefully prolong the life of the heaters. I'm also placing a CL-60 Thermistor and .047uf line rated cap on the mains line before the transformer primary in the hopes of having the heater supply coming up more slowly to stop the 12V from slamming into the heaters as they take a while to get to their full resistance. I may also try putting a thermistor on the 12V secondary to help achieve the same result.