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Cavalli EHHA Embedded Hybrid Headphone Amp - Page 16

post #226 of 1816
OK, guess that's to be expected with tubes.
Just need to troubleshoot why I aint got the .22V across the output resistors and we should be listening soon(mosfets are dead cold). All measurements are spot on with the Cavalli initial setup page except the .22V across those 2.2ohm's.
post #227 of 1816
Quote:
Originally Posted by digger945 View Post
OK, guess that's to be expected with tubes.
Just need to troubleshoot why I aint got the .22V across the output resistors and we should be listening soon(mosfets are dead cold). All measurements are spot on with the Cavalli initial setup page except the .22V across those 2.2ohm's.
Crank up R21 on either side until you see the voltages go up across the output resistors.
Once you have 0.22Volts across the resistors, then adjust R6 to get pin6 of the opamp to read 0 volts.

Then check voltage across output resistors again and readjust R21 if need be to get 0.22Volts across o/p resistors.
post #228 of 1816
Got it!
OK i got like 60 and 70mV on pin 6 so I'm gonna power down and put the opamps in now.
post #229 of 1816
Quote:
Originally Posted by digger945 View Post
Got it!
OK i got like 60 and 70mV on pin 6 so I'm gonna power down and put the opamps in now.
Cool..once you have the tubes balanced and bias set..prepare for total awesomeness!!
This truly is the Emperor of Hybrids!!..
post #230 of 1816
Thanks for the help Sachu!
We might just have an Aikido beater here boys.

Initial impression after just a couple of minutes, this little booger ROCKS!!! I totally love the (fill in your fav audio adjective here).
Biased at just under .22V on the outputs, the heatsinks are not so hot that you can't hold your hand on 'em for as long as you want.
Can't wait to try the bugle boy 6gm8's, 6dj8's, 7dj8's(thanks Ludoo/Donald/wiatrob), and of course the 6H30's.
post #231 of 1816
Is(has) anyone building the BJT version?
post #232 of 1816
I have two more boards. I think I'm gonna socket the outputs and associated parts to try different stuff like BJT's. I also have some Renesas mosfets I'de like to give a listen to.
You can see the sockets in the upper right of the pic above, I came close to doin it on this one but wanted to hurry up as we have just closed on a new home and will be busy moving all this and next week. This will be my last work at the bench for at least a week or more.
post #233 of 1816
Quote:
Originally Posted by digger945 View Post
Thanks for the help Sachu!
We might just have an Aikido beater here boys.

Initial impression after just a couple of minutes, this little booger ROCKS!!! I totally love the (fill in your fav audio adjective here).
Biased at just under .22V on the outputs, the heatsinks are not so hot that you can't hold your hand on 'em for as long as you want.
Can't wait to try the bugle boy 6gm8's, 6dj8's, 7dj8's(thanks Ludoo/Donald/wiatrob), and of course the 6H30's.
hah! wicked!!toasting another EHHA with a Widmer's IPA.. enjoy the wonderful amp..can't wait to see it all squared away in a case.

I was however expecting to see 4 boards in balanced config or is that at a latter stage.
post #234 of 1816
Thread Starter 
Excellent work, looks great and I'm itching to hear mine.. one day

Got the new case ready for it, just need to finish the boards
post #235 of 1816
congrats ..dB

edit :
Quote:
Originally Posted by digger945 View Post
We might just have an Aikido beater here boys.
interesting

Quote:
Originally Posted by digger945 View Post
.......and of course the 6H30's.
now this I am very interested in
post #236 of 1816
Widmers must be better than Bud eh.
You know I think I'll wait and see how this one does before considering a balanced configuration. Besides that leaves me with two more boards to play with(see post above). I didn't mention that I couldn't find the schematic with the H-PS-1 power supply parts so I just used a 12V 1A wallwort for the heaters in series. I have a wee bit of low freq hum but I'm sure it will probably go away witha better heater supply maybe. I noticed that the ground on 6.3V heater supply on the Cavalli website is connected to the board star ground in Alex's wiring section.
Still gotta do the S22. It would be killer if the S22 had a tube heater output.

One more thing I noticed. As soon as I powered down and installed the opamps I checked the offset not 2 seconds after powering up again and it was at zero already.
Stuck a piece of wire between the 12V ground and star ground and the hum went way down.
post #237 of 1816
Thread Starter 
how is it rigged up now, bench psu?
post #238 of 1816
Quote:
Originally Posted by Ynis Avalach View Post
Is(has) anyone building the BJT version?
yes, the proto team built up 2 - verdict at the time was the the BJT and mosfet sounded similar but if you can build with a mosfet , why not

I did build one channel and test the BJT version but I never listened to the BJT as an amp..dB
post #239 of 1816
Quote:
Originally Posted by digger945 View Post
Widmers must be better than Bud eh.
You know I think I'll wait and see how this one does before considering a balanced configuration. Besides that leaves me with two more boards to play with(see post above). I didn't mention that I couldn't find the schematic with the H-PS-1 power supply parts so I just used a 12V 1A wallwort for the heaters in series. I have a wee bit of low freq hum but I'm sure it will probably go away witha better heater supply maybe. I noticed that the ground on 6.3V heater supply on the Cavalli website is connected to the board star ground in Alex's wiring section.
Still gotta do the S22. It would be killer if the S22 had a tube heater output.

One more thing I noticed. As soon as I powered down and installed the opamps I checked the offset not 2 seconds after powering up again and it was at zero already.
Stuck a piece of wire between the 12V ground and star ground and the hum went way down.
My heater ground is separate from the star ground. No hum whatsoever considering that the input side of one of the boards is only 4 inches away from the S22 toroid.
post #240 of 1816
Quote:
Originally Posted by smeggy View Post
how is it rigged up now, bench psu?
Sigma used for Dynamite.

Kinda like stealing from the electic company
Wallwort on the floor is for heaters.
I really wish I could figure out how to make my new camera get a little bit better pictures. Not enough time in the day.
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