The Amp Garage

May be there is a bit of misunderstand, the power tube is a GU-50 and with only one in SE it is a 15W amp

Many people call it a ruggedized KT88

https://en.wikipedia.org/wiki/GU-50

Franco

Thanks Phil_S Yes a compromise there is and it is in the fact I must use a custom PT (not able to find one that can perform the necessity of this amp For a better understand of what I'm talking about, here the schematics of the amp on which this project is based and the amp I was thinking about for ...

Thanks Stevem I'm not asking about a project I'm asking about a configuration What I want to know is if the more people would like a small Power amp (around a 1W of Power) with two final Power options, one being a Triode (6N6P) and the other being a Pentodes (EF80) Or if the more people would prefer...

I'm planning a small amp in the order of around 1W of Power The originale schematic uses a single 12BH7 with triodes in PP and Is fine for Blues and others Styles (Wangs Mini 5) Initially I was tinking to follow the project only swapping tubes with tubes I've under hand So 12AX7 become 6N2P and 12BH...

Each diode you put in series will lower the the voltage of around 0.7V

You can lower the voltage also with an in series resistor, the difference is that the use of a resitor implies a bit of math using the consumption of the relay, this math is not necessary if you use the diode trick

Franco

https://el34world.com/projects/relay_sw ... e_vignette

https://el34world.com/Forum/index.php?topic=14468.0

Franco

Just remember that after a few time the Carbon Comp resistors has the tendency to drift and often in a bad way so the function of the circuit will be altered and easily not in a pleasant way

K

Just curious

When you performed the test, did you disconnected completely the PP Pot from the circuit ?

Franco

Perfect

Another step, if necessary, would have been to replace the artificial CT with a Humdinger

Franco

If .3 ohm were measured is because the multineter wasn't able to measures the real resistance and consider It as a short, no open circuit

K

For those resistance measures I've an old but special item by UnaOhm It can measure from a very low value, in the order od 1/10 of ohm to Mohms

I usually use It when measuring Transformers windings

Franco

About pedals I don't know (May be it can apply if they are tube effects on rack, or may be it can be adapted also to SS circuits ?) but about rack Preamp this same question was discussed years ago at EL34world and our friend Sluckey find a solution See here the thread and give a look to the solution...

https://nepp.nasa.gov/docuploads/06AA01 ... 8739.3.pdf

https://electromet.com/wp-content/uploa ... D2000a.pdf

Franco

I suppose that as the Solid State Rectifier version also your 1969 amp has 4 Power Tubes You don't specific which is the Tube Rectifier on your amp and say .... the amp I am working has a tube rectifier .... has a tube rectifier (no more I suppose) Assuming it is a GZ34 like in the Sunn Sceptre of 1...

Thanks

Franco