Thanks guys.
It sounds great to me 6L6, very sensitive input though.
stajo, the 6JN8 is basically a 6GH8 with different pinout. Based on the triode-strapped pentode curves I found online for the 6GH8. They were fairly accurate. At the bias point I'm using the mu is about 20.
Not sure about a circuit board yet. We'll see how this turns out.
I was way off on the input voltage readings. Still about 9W RMS though. I'm not sure what happened, I must have been looking on the wrong scale or something on my scope. I took the measurements again.
I will open another thread in the tubes/valves since I don't want to violate the photo gallery rules and talk too much about this.
It sounds great to me 6L6, very sensitive input though.
stajo, the 6JN8 is basically a 6GH8 with different pinout. Based on the triode-strapped pentode curves I found online for the 6GH8. They were fairly accurate. At the bias point I'm using the mu is about 20.
Not sure about a circuit board yet. We'll see how this turns out.
I was way off on the input voltage readings. Still about 9W RMS though. I'm not sure what happened, I must have been looking on the wrong scale or something on my scope. I took the measurements again.
I will open another thread in the tubes/valves since I don't want to violate the photo gallery rules and talk too much about this.
this an 832 pp amp in the works, OPT is 8k a-a to 8 ohms,
concertina drive, 12at7, a line amp using the 12au7 is built in,
and a vsps phono stage, makes this amp a full function integrated amp...
and no GNFB with the addition of the line stage...
this is my parallel SET using the 4P1L's, OPT is 2.5k to 8 ohms,
target operating point is 250 volts at 60mA..
input voltage amp is a 6J9 in pentode mode for more gain,
a 6N1p in a broskie cathode follower config to drive the output stage grids...
another 6550 pp amp good for about 50 watts per channel..
OPT is a 431 like without the ultralinear taps, since i am operating the 6550's in pentode mode....
12BY7 input and 6CG7 LTP phase splitters complete the tube line-up...
concertina drive, 12at7, a line amp using the 12au7 is built in,
and a vsps phono stage, makes this amp a full function integrated amp...
and no GNFB with the addition of the line stage...
this is my parallel SET using the 4P1L's, OPT is 2.5k to 8 ohms,
target operating point is 250 volts at 60mA..
input voltage amp is a 6J9 in pentode mode for more gain,
a 6N1p in a broskie cathode follower config to drive the output stage grids...
another 6550 pp amp good for about 50 watts per channel..
OPT is a 431 like without the ultralinear taps, since i am operating the 6550's in pentode mode....
12BY7 input and 6CG7 LTP phase splitters complete the tube line-up...
SE 813 guitar amp
OK, not an audio amp but it has been so long since I build my guitar amps that I just had to do it
And besides, it is a test setup as well for the 813. Another step towards getting them into my audio system.
It uses the external power supply that I can use for either my 300B mono's or the upcoming 813 mono's.
Right now they run on a measly 350V, producing around 5W (10% of the filament power
).
The filament runs on dc using Tomchr's universal filament reg. That 5 Amps is the limit of the LM22679 IC but it works well. Slow start and dead quiet.
Driver is an EF184 with a 2V red LED and a 10M45S CCS.
Next step: upping the HT 3x...
OK, not an audio amp but it has been so long since I build my guitar amps that I just had to do it
And besides, it is a test setup as well for the 813. Another step towards getting them into my audio system.
It uses the external power supply that I can use for either my 300B mono's or the upcoming 813 mono's.
Right now they run on a measly 350V, producing around 5W (10% of the filament power
).The filament runs on dc using Tomchr's universal filament reg. That 5 Amps is the limit of the LM22679 IC but it works well. Slow start and dead quiet.
Driver is an EF184 with a 2V red LED and a 10M45S CCS.
Next step: upping the HT 3x...
Attachments
Ah so we can post instrument amps? Here is my bass guitar amplifier:
It's basically built on top of an op-amp based parametric tone control, tight fit indeed. Power amplifier is a pushpull 6FD7. HT+ is using an SMPS that was meant for Nixie tubes to save space and cost. OPT is a power transformer with 220-110-0 primary and 0-4.5V secondary as output to speakers. Puts out around 7-8 watts. It still needs more gain so there will be a 6N23P/6N2P gain stage at the input. Quite surprised with the wide frequency range the OPT transformer is giving!
It's basically built on top of an op-amp based parametric tone control, tight fit indeed. Power amplifier is a pushpull 6FD7. HT+ is using an SMPS that was meant for Nixie tubes to save space and cost. OPT is a power transformer with 220-110-0 primary and 0-4.5V secondary as output to speakers. Puts out around 7-8 watts. It still needs more gain so there will be a 6N23P/6N2P gain stage at the input. Quite surprised with the wide frequency range the OPT transformer is giving!
Attachments
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