• 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.

#26 pre amp

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Hi Rod,

If I don't use the input volume pot as per Thomas advice using his TVC at the ouput, can I use this schematic?

Thank you
Felipe
 

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  • DHTline_battBias.jpeg
    DHTline_battBias.jpeg
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Thanks again Rod,

-That's a good new, yes I will use Salas HV reg so can save 2nd inductance (a lot of money):)

-About PSUD2 wich load I have to use to simulate the 26 + Salas reg.? PSUD2 don't have AZ1, there is other tube on the library to simulate?

-For your heaters to simulate the needed PSU wich load I have to use?

Cheers, Felipe
 
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Thanks again Rod,

-That's a good new, yes I will use Salas HV reg so can save 2nd inductance (a lot of money):)

-About PSUD2 wich load I have to use to simulate the 26 + Salas reg.? PSUD2 don't have AZ1, there is other tube on the library to simulate?

-For your heaters to simulate the needed PSU wich load I have to use?

Cheers, Felipe


hi Felipe,

if you remove the .txt from the filename, here is a PSUD2 file for 26 with 6V 50VA, and recommended support components.....

.
 

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Sorry I don't understand you, I want to try battery bias, wich load value for 26+Salas reg & wich load value for heaters?

Can't open your file, how can do?

For the 26 B+ model, please use current load, 10mA (or change the 10mA to the operating point you have chosen).

For Filament, choose Constant Current load, value = 1.05A

to open PSU file, it must end in .PSU. You have to delete the .txt I put at the end, so I could post it.
 
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Rod mentioned 5R4GY as rectifier, and this is a very good choice - what I use and better than all the GZ types. It will be sufficient for most SE 300b amps. for a preamp AZ1 mesh and 80 or 5Y3 (same, octal base) may be better still.
5R4GY has more voltage drop than others, but usefully is 2A.

Andy

Thanks Andy, Rod suggested 5R4GY to simulate the AZ1 in the PSUD2

Are you using 138V for B+?

Felipe
 
OMG

Rod,
All I can say is Holy $hit!! The DHT board has made my amp using a 26 to drive my 2A3 DEAD QUIET. And preserved the sound of an AC heated triode. I think its time to tear apart my friends Welborne amps and rip out the poorly designed DC circuit on the 300B. It sounds lifeless so I suspect your board will perform like my #26.
The build was a piece of cake using that heat sink you recommended. I had to drill some holes in the sink since the holes were too large and use self tapping machine screws. be sure to clean and sand smooth the hole since it could short the transistor to sink.
 
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