For information
I've got a somewhat electronic scrap / schematics from an estate (a +90 year man).
I found the schematic here, which I've attached.
There comes several schematics as I have drawn them clean.
Here is one schematic with, for me unknown low-voltage tube, 50B5.
I would probably raise the voltage and use EL90 tubes.
You must be disregarded pin numbers on the tubes.
Regards
Benny
I've got a somewhat electronic scrap / schematics from an estate (a +90 year man).
I found the schematic here, which I've attached.
There comes several schematics as I have drawn them clean.
Here is one schematic with, for me unknown low-voltage tube, 50B5.
I would probably raise the voltage and use EL90 tubes.
You must be disregarded pin numbers on the tubes.
Regards
Benny
The 50B5 is identical to the 50C5, however, the pinouts are different. That was the big problem with the 50B5: it has the same pinout as the 6AQ5, but that caused problems when using the 50B5 in a series string, as the voltage could be quite high before it warmed up. So they changed the pinout, and made the 50C5.
Benny,
The 50B5 data sheet is here.
That circuit is typical of cheap, LOFI, AC/DC designs. It used a transformerless 1/2 wave rectified B+ PSU and a 150 mA. series heater string. It's inexpensive and deadly dangerous.
The only protection the owner got was from the floating speaker setup. Notice zero NFB in combination with full pentode mode. That means lots of distortion and wretched voice coil control.
It's not that long ago that folks living in certain localities were forced to use equipment of that ilk. Their house current was "110" VDC.
A good amp can be built around that sort of power tube, but not with that crappy PSU. Bridge rectify "120" VAC. 0B2 regulate g2 B+. You can bank on that design being used with a piezoelectric phono cart. as the signal source. HF info. was already rolled off. The parts values shown will cause HF info. loss, if a full range signal is applied.
The 50B5 data sheet is here.
That circuit is typical of cheap, LOFI, AC/DC designs. It used a transformerless 1/2 wave rectified B+ PSU and a 150 mA. series heater string. It's inexpensive and deadly dangerous.
The only protection the owner got was from the floating speaker setup. Notice zero NFB in combination with full pentode mode. That means lots of distortion and wretched voice coil control.It's not that long ago that folks living in certain localities were forced to use equipment of that ilk. Their house current was "110" VDC.
A good amp can be built around that sort of power tube, but not with that crappy PSU. Bridge rectify "120" VAC. 0B2 regulate g2 B+. You can bank on that design being used with a piezoelectric phono cart. as the signal source. HF info. was already rolled off.
The parts values shown will cause HF info. loss, if a full range signal is applied.Hello
Peaceful Eli. I had no intentions of building the amplifier. I showed it just as an example of a design from the late forties, early fifties.
I have found the following designs in the estate.
6SJ7-6N6-6V6 in pp
Something 6SQ7 - 6V6 in pp
6SJ7-6SN7-6L6 in pp
12SQ7 - 12L6 in SE
There are more but I have no overview at the moment.
Benny
Peaceful Eli. I had no intentions of building the amplifier. I showed it just as an example of a design from the late forties, early fifties.
I have found the following designs in the estate.
6SJ7-6N6-6V6 in pp
Something 6SQ7 - 6V6 in pp
6SJ7-6SN7-6L6 in pp
12SQ7 - 12L6 in SE
There are more but I have no overview at the moment.
Benny
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