My first Express build...its alive!..pic added...question?

[guitarsnguns04]

I was thinking of adding the fast/gradual switch and cut control like a K amp. Does anyone have a layout for this? I cant seem to find one.

[guitarsnguns04]

nevermind...I got a k-80 komet yesterday and took a peek in to see whats going on.

[guitarsnguns04]

I just changed out my 6v6s for some JJ KT77's...wow what a difference..but thats another story all together. I took some readings and found my heater voltages to be 6.59-6.6 Volts. Should I be concerned about this being slightly higher? I had 6.3 at startup but now its up. Wall voltage was 118.3 vac..Thanks in advance

[Aurora]

Nice build!

But - I'm still wondering about that fast/gradual thingie....
If someone has a drawing, - or an explanation - that would be ever so nice.....

[guitarsnguns04]

https://tubeamparchive.com/viewtopic.ph ... ual+switch


check this thread for the fast gradual switch...


what about those heater voltages anyone?? Is 6.6 volts something I should be concerned about?

[fishy]

Filament supplies are rated with a load. If you only drawing a small amount from the supply, it can be higher than you might think. WHether it is bad for your filaments is a topic of discussion best left to others... Spec usually says +/-10%

Wish my incoming voltage was 118.... mine is up at 123v putting my heaters close to 7v. Needless to say, I am not keen to be running my gear to much at the moment.

Toying around with the idea of a variac / regulated supply just for the purpose of getting recommended voltages on the heater. I also might put resistors in the filament line also.

I think there is a 6v6 variant that uses 2X the heater current so I might look at that for the express to see if it helps drop the filament voltage at all.

[Trigger]

Nice build!

But - I'm still wondering about that fast/gradual thingie....
If someone has a drawing, - or an explanation - that would be ever so nice.....

Here is a schematic showing a fast/gradual switch. It is a switch to change the plate load resistor for more gain, less gain. It has an 82k then switches in an additional 22k to get you close to the original Express circuit.

[guitarsnguns04]

fishy..thanks for the reply..
trigger thanks for the schemo..