pre's changing tone/presence controls???

[tonejones]

Hi all,

Am consulting some of the amp gurus that live here on the board....HELLPPP!!!!!!

After installing an IEC Mullard in V1 and a Sylvania in V3/PI of my Hughes & Kettner head (out came a very used Ei in V1 and the factory H & K tube in V3/PI), I have noticed that my tone knobs/presence controls don't seem as active as they once were.

They are still working,.......

but where the bass knob once took the amp into quasi-flubby fender-esque territory, it now only does some warm undertones.......

The mid knob I like alot better now actually (but who wouldn't with a Mule in V1)????

The treble knob will go straight into buzz saw territory on the upper levels now (with seemingly only very subtle changes otherwise)........

Presence knob seems to roll off only the very highest/brightest treble, and brings in the warm undertone bass that I described above.....

I half-jokingly stated to my bandmates that this pre change turned my H & K into Marshall-Lite.....and now the tone/presence controls are starting to remind me of a few Marshalls!!!! Being reminded of a Marshall isn't a bad thing by any means, and the amp has a happening sound with the NOS pre's, but I can't help but feel it's robbed the amp of quite a bit of versatility as well......

I really do dig the sound it has right now (kinda reminds me of a 5150 with all the Peavey baggage removed), but it's also pretty one dimensional for a monster 4-channel-switching over-engineered German amp head (used 2B clean, a vox-like crunch, and a rather too thick IMHO 2 choices of heavy overdrive). I'd love to have this sound on just the OD or Crunch channel(s), but now the OD sounds like a more intense version of the Crunch instead of having it's own characteristics.

Is this a characteristic of a Mullard and/or Sylvania NOS??? (really second guessing the Sylvania at this point).......

One of the reasons I'm asking is this amphead is the biggest pain in the ### to get into for changing pre's you've ever seen (8 screws, 8 allen wrench bolts, and then pull the chassis just to get to the pre's).

I'd love to let just the chassis sit out and experiment for awhile, but alas I have gigs and can't do that for at least the next few months.....

All comments and help greatly appreciated......