Jet City Amps Appreciation Thread!

[J.custom]

Cool, got the tube changed and the amp sounds so much better! Harmonics are coming through so much better and there's less fizz and more clarity. Bought the Tungsol 12AX7 cos they were sold out of JJs and no regrets at all.

I kick in a borrowed RC booster with the treble backed off to get a nice and fat singing tone.

 

[Ratboy]

=Ratboy

Actually, fixed bias amps can have their bias adjusted, assuming a variable resistor is used in the bias circuit. Some companies, like Mesa Boogie, use a fixed resistor and forces the consumer to buy their own power tubes. Smart owners immediately swap out this fixed resistor for a variable one to make their tube buying a lot more flexible.

The naming 'fixed bias' IMHO can be rather confusing at times. It means fixed because once set it at that level, it will stay at that level unless you adjust the variable resistor again. However, it should be noted that the bias can drift a little bit, depending on how much the power tubes are burnt it.

Also, cathode biasing has one very big flaw, in that you cannot dictate the bias value that is optimal for the power tubes that you have in your amp. To add on to ratboy, cathode biasing can also squeeze out too much potential out of the tubes and leave them with a very short lifespan, which was the case with the previous generation Vox Custom Classic amps.

And to add further confusion to all
You can actually have "variable cathode bias" : )
I implemented this on my Thd Univalve
ha ha ha

 

[J.custom]

haha and what does that do?

 

[Ratboy]

Most Cathode biased amp got no further settings for bias
So you just swap tubes and live with it.

This mod allows you to play around with the bias within a certain range
even though its cathode biased.

And contrary to common believe (at least from what i have read)
i find that a slightly cold bias sound better .....

 

[J.custom]

Bump, any updates guys? Recently I've just been plugging my guitar straight into the amp with a vol pedal in the loop, Killer tone!

 

[CyanideJunkie]

Added a tremolo pedal to my signal chain, got a nice Fender Bandmaster tremolo thing going on now. Drive-wise, sounds great by it's own but absolutely kills when booted by my AC booster, and even better when stacked again with the Andora's Box.