New Tubes for JMP-1 Preamp...choices

[robertkoa]

I've just replaced the power amp tubes with Mesa Boogie EL84s and have been fairly happy with that.

I've decided it's time to replace the Pre-amp tubes. My aim is to limit the diod-clipping-ness of the unit and give it a bit more tube warmth.

JJ803s seem to be a favorite

From a post on here along time ago: "Since the JMP 1 uses diode clipping as well- the JJ803s might be the perfect tubes for it- they have a huge plate- different construction etc. and may overshadow the diode clipping as well and provide even more convincing tones"

I play mainly 80s rock, so looking for smooth and warm, not fizzy.

I'm not tube-savy so educate me with your knowledge!

I have a hughes and kettner tubeman - and it sounded similar to the vintage Champ I had on clean tones .

BUT as the gain was turned up it had a slight rasp above medium gain.

I can NOT hear what the builder had for lunch when he designed it BUT it was probably the diode clipping circuit ...

I had a tech install a JJ803 S and the gain is more gradual wider sweet spot and the buzz is nearly or completely inaudible .

I am curious IF that tube will also smooth out the JMP1 .
That tube has a huge plate and not just a subtle difference in the Tubeman .

The Tubeman runs full plate voltage - but it may really improve the JMP if it runs normal plate voltages which could be significant.

So I don't think you should buy a new car or new preamp till you try them .

?

 

[robertkoa]

I've just replaced the power amp tubes with Mesa Boogie EL84s and have been fairly happy with that.

I've decided it's time to replace the Pre-amp tubes. My aim is to limit the diod-clipping-ness of the unit and give it a bit more tube warmth.

JJ803s seem to be a favorite

From a post on here along time ago: "Since the JMP 1 uses diode clipping as well- the JJ803s might be the perfect tubes for it- they have a huge plate- different construction etc. and may overshadow the diode clipping as well and provide even more convincing tones"

I play mainly 80s rock, so looking for smooth and warm, not fizzy.

I'm not tube-savy so educate me with your knowledge!

That may have been a post of mine from long ago.

I had a tech put a JJ803S which has a very long plate
In the H&K Tubeman . The tube 803S has more gradual clearer gain and the medium gain to medium high gain [ when the diode clipper kicks in is NOT mildly fuzzy any more ] a big difference not like ordinary tube rolling .!

I was thinking it might even be more dramatic in two tube preamps and wondered if any had tried it .

I wonder also if it might warm up the Friedman IRX and IRD which sound a bit thin on cleans and a bit harsh on OD sounds ...modern players might want that buzz to sound aggressive or angry ...but I don't .

So let me know if it works.

You don't need a new amp or preamp or a new car yet.

Diode clipping sounds like a very faint fuzz tone in the signal chain - not an xray hearing thing