• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

OTL Help

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#21
LOW WATT OTL

Hi,

futt.gif


This one by the famous Julius Futterman.

:att'n: DO NOT use the 117VAC line voltage but a seperate 120VAC on the transformer.

Also don't forget either that these older designs were developped for 16 Ohm speaker load so you better use at least two more output tubes.
Beef up the PSU a bit and you're in business.

Another fine candidate for the output stage would be the Russkie
6C19-P.
It is reported to sound great,I haven't heard it yet and the circuit may need some adapting.

Keep in mind that I never actually built this one so I can't tell how it sounds,whether it is reliable and so on.
It looks pretty straightforward to build and well thought out.

I'll give a link to the side so you can all eat your hearts out:

http://www.audiodesignguide.com/otl/index.html

Cheers,😉
 
#22
Hi, Frank,

There are obviously miststakes in your posted LOW WATT OTL circuit. The aondes of 12B4 should not be connected to the anode of 6S4.:bawling:

Please also note that the filaments of the output tubes 12B4 are connected directly the LINE supply which is extremely dangerous to DIYers. :bawling:

Regards,
The Seven.
 
#23
AINT MY DRAWING.

Hi,

Sorry fellows,

My blind trust in Julius Futterman has just been deeply damaged.🙁

12b4.gif


This one better?

DO NOT use the 117VAC line voltage but a seperate 120VAC on the transformer.
Click to expand...

DO NOT use the 117VAC line voltage but seperate 120VAC and 6.3VAC secondaries on the powerxsformer.:att'n: :att'n: :att'n:

Happy?😎

P.S.Seven,the 6.3VAC on the primary side is actually ok since it is a separate winding.It's just drawn in an odd way on the circuit diagram.
No worries.
 
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