18watt lite options ???

[GodoFre]

Hello to all:

I intend to build an 18W, with volume and tone control, taking advantage of "the irons" of an old amp, made in kit form (I don't have a schematic). The transformers work correctly; I only have an input connector and 2 potentiometers: volume, of 1M log and tone, of 500K log.

I have consulted the different versions of the forum: lite, lite II, lite IIb and lite III and I have the following doubts:

1.- B+. Each schematic has a different value for the supply voltage. I think I have seen between +360 volts and +305. The current push pull on my hardware has on the cathodes of the EL84s a 150R resistor, in parallel with a 100 uF capacitor. I will need to use zeners to accommodate the voltage -things about using an old transformer-, but I am not clear on what value to leave it at. What value of B+ is more suitable to achieve a balance between tonal quality and tube life? Should I change my cathode resistor?

2.- What modifications should I make to be able to use my volume potentiometer (1M log, instead of the 500K log indicated in the schematics)?

3.- Optimal values of the coupling capacitors and tone stack?. Each schematic makes a proposal, with slight modifications from one version to another. Which one should I choose?

Thanks, apologies for so many questions and best regards,

GodoFre

[Bieworm]

Hi there

Maybe you get a good start with the 18W Modern Classic, but just build the normal non tremolo channel?

viewtopic.php?t=25606

[JMPGuitars]

Look at the Lite 2b(ish). That's the newest/most modern version. If you want hi/lo inputs for some reason, you can copy the jacks from Superlite TMB.

To know what your B+ should be, that depends on your PT. Our typical target is 345VDC +/- 5V.

Power tube dissipation target is 85%. Old voltage target transformers on new wall voltages tend to like a 180 ohm cathode resistor (290-0-290 secondaries).

1M or 500K doesn't matter that much for the volume pot. There may be an effect on the sweep range, but it may not matter much either.

Thanks,
Josh

[GodoFre]

Thanks for the input !

Following JMPGuitars suggestion, I have built the Lite 2b (ish) version.

However, I have some difficulty, which I describe in a separate post.

Glad to be part of this forum !