Marshall dsl 100

[greg500]

I am going to replace el34s with kt88s. bias rating?

[Jazz P Bass]

Bias voltage will be more negative.
Physically, are those fat tubes going to fit side by side?

[olddawg]

I'm just curious as to why you would bother? What difference are you after?

[greg500]

I'm just curious as to why you would bother? What difference are you after?

The KT88s sound thicker than the EL34s

[greg500]

They fit. I was looking for a numerical number for the bias.

[Jazz P Bass]

The 'numerical number' really does depend on (1) the B+ & (2)how hard you are going to run them at idle.
Ball park figure I would say -60 - -50 volts.

[Alex R]

The KT88s sound thicker than the EL34s

Well they LOOK thicker . Soundwise there may be a difference but unless the amp is unhappy with the KTs it will be slight, and probably in the subjective area.

Will the power transformer supply 0.4A more heater current? (I have read than some KT88s draw near to 2A each in which case that's 2A more for the set of four) - if the heater voltage for KT88s drops significantly lower than for the EL34 set then the transformer is overloaded.

as to the bias just measure it and adjust as normal, although you may find the DSL isn't able to supply enough bias voltage.

[olddawg]

The KT88s sound thicker than the EL34s

Interesting, most people convert KT88 amps to EL84s for a thicker more "British" sound. I guess it all depends on what you mean by thicker. In this amp I doubt it will make a real difference unless you are playing through the clean channel dimed and boosted. Better be a big venue though, lol.

[Gtr_tech]

KT88s need higher plate supply to really "wake them up". Putting these in an amp that runs less than 500v on the plates won't be of much advantage other than a slight tone change. A KT66 would be a better choice providing the amp can bias them into their "happy" zone and they physically fit.