One when stationary and one when traveling
For desk use (4-5 hours/day) EL84 SE that is usually operated single-stage (input from USB soundcard straight to trioded EL84 with 98db OB speakers 1 meter away) but can be switched to 2-stage if required.
For travel, all direct-heated headphone amp that plays for some 9 hours hours on one battery charge.
If not obvious from the pictures, both were made mostly of junk parts (but the labeling on the headamp 'housing' fits quite well ...)
For desk use (4-5 hours/day) EL84 SE that is usually operated single-stage (input from USB soundcard straight to trioded EL84 with 98db OB speakers 1 meter away) but can be switched to 2-stage if required.
For travel, all direct-heated headphone amp that plays for some 9 hours hours on one battery charge.
If not obvious from the pictures, both were made mostly of junk parts (but the labeling on the headamp 'housing' fits quite well ...)
Attachments
Schematic is in this thread http://www.diyaudio.com/forums/tube...amp-all-tube-direct-heated-portable-fits.html
Hi Kevin,
I've heard this formula D3a-GM70 SE in my friend's system. Sound is a bit harsh, not much warm, rich tone... like traditional SET amp.
Is it enough gain for GM70 (over 200Vp-p) ?
Mine is very pleasant to listen to without being particularly euphonic.. 
Actually in class A1 at 1kV about 160Vpp is all that is required.
Significantly less than 1Vrms is required to drive it to full output.
IT is 1:1
Opt is 7K:8
D3A runs at 20mA, GM70 at 120mA..
Currently using graphite plate GM70s.
Actually in class A1 at 1kV about 160Vpp is all that is required.Significantly less than 1Vrms is required to drive it to full output.
IT is 1:1
Opt is 7K:8
D3A runs at 20mA, GM70 at 120mA..
Currently using graphite plate GM70s.
Mine is very pleasant to listen to without being particularly euphonic..
Significantly less than 1Vrms is required to drive it to full output.
IT is 1:1
Opt is 7K:8
D3A runs at 20mA, GM70 at 120mA..
Currently using graphite plate GM70s.
My system has the same formula with you: DHT pre amp --> power amp including penthode tube in triode mode- IT- power tube.
Hi, I have a pair of new GM70 but do not have any plan to use. Do you want to take it for free?
Just met minhhp6365 at Thivan last week, so I known you did move your home. Your 4D32 PP mono block look so nice
. How is new life ? Tks for your kind! How do I get those GM70s ?
Thanks! I forgot to add these details too:
All Russian Mil-Spec FT-3 Teflon Signal Caps
All US Mil-Spec Silver wiring
Split Power Supply with two chokes on each side
All gold plated porcelain sockets
Gold Lion KT88s
Soviet Metal Base Mil-Spec hole plate 6N8S (MELZ) - 6SN7
Soviet Metal-base mil-spec 6S2S (MELZ) - 6J5
It does sound incredible...
All Russian Mil-Spec FT-3 Teflon Signal Caps
All US Mil-Spec Silver wiring
Split Power Supply with two chokes on each side
All gold plated porcelain sockets
Gold Lion KT88s
Soviet Metal Base Mil-Spec hole plate 6N8S (MELZ) - 6SN7
Soviet Metal-base mil-spec 6S2S (MELZ) - 6J5
It does sound incredible...
I'm sure it does! Gold Lions are my favorite KT-88, tried them after a pair of JJs drifted in bias then died prematurely- and I never looked back after making the switch.
Very good, having two chokes each side... In my experience, it seems there's no such thing as too much power supply- or too much filtering. Must be very quiet and likely sound solid and transparent with a stable soundstage.
The ceramic sockets look incredible and with the other mil-spec components, I'm sure the amplifier will last a lifetime -a joy forever.
Very good, having two chokes each side... In my experience, it seems there's no such thing as too much power supply- or too much filtering. Must be very quiet and likely sound solid and transparent with a stable soundstage.
The ceramic sockets look incredible and with the other mil-spec components, I'm sure the amplifier will last a lifetime -a joy forever.
Mine is very pleasant to listen to without being particularly euphonic..
Significantly less than 1Vrms is required to drive it to full output.
IT is 1:1
Opt is 7K:8
D3A runs at 20mA, GM70 at 120mA..
Currently using graphite plate GM70s.
I'm using power E810f- IT- 300B XLS, my E810f runs 180Vak 21-22mA and have high frequencies oscillation. These tubes work normally in plate choke loading and resistor loading in my prior amps. I intend to try tube 7788 and hope they don't the same problem.
Is the only controversy for summer time. Listen music and enjoy the hot weather or visceversa. Good picture. Regards
Rock solid and entirely quiet.. I had a tiny amount of hum until I lifted the preamp chassis ground and then radially connected it to the power ground using 12ga silver mil-spec wiring. Zero hum now...
Circuit courtesy of Lance Cochrane.
look on the bright side, infra heaters with ambient lighting which also amplify signals.Is the only controversy for summer time. Listen music and enjoy the hot weather or visceversa. Good picture. Regards
833 at full blast could make a few breakfast toasts.
no silicon can do