Conference napalm::guitar

    I think it's your chain, which is creating this sympathetic resonance
    thing from hell.
    
    Try doing your chain this way:
    
Charvel model6 --> Boogie Preamp --> 600 LX --> Marshall 4x10
    		    |	    | |  --> 600 LX --> Marshall 4x10
                    + GSP21 L |   
                            R +
    
    Guitar plugged into Boogie Preamp.  Mono FX send out of Boogie preamp
    into Mono-in on the GSP21.  Stereo FX-out on the GSP21 into the 
    Stereo FX-in on the Boogie.  Stereo out on the Boogie into Left and
    Right on the power amp, and into their respective cabs.  I'd can the
    SPX 90 as it's a piece of crap, and really screws up anyone's tone.
    I also have reservations about plugging directly into the FX unit,
    and then into the preamp?!  You may also notice I canned the hush out
    of your signal chain ... bogus for tone!!
    
    Anyways, the problem you have sounds like simple microphonic feedback.
    You learn to control it someway.  Myself, I play with so much gain,
    sometimes I microphonically feedback.  I usually setup a "kill" patch
    so I can just shut the damn thing off when I'm not playing.  When I'm
    playing, the feedback is masked.  A kludge fix, but it works.

>    I'd can the SPX 90 as it's a piece of crap, and really screws up
>    anyone's tone.
    
    Don't hold back, Bill, tell us what you really think of the SPX-90.
    
    ;^)

If your Valve preamp sits on top of the speaker cabs, could be a preamp
tube "on the way out". This would fit the scenario of only seeing the problem
when the volume is turned up.
*Dave

Thanks,

By the way, my boogie is not always 'in the chain.'  The whole
FX loop can be switched off by the GSP.  The problem is present
when the boogie is not in the chain - I should'a mentioned that.

RE: -.1
   I recently replaced the tubes.  No change.

RE: .1
   I'll give it a try tonight.  I think I tried that wiring when I first
   got my GSP & Boogie.  I think I disregarded it because I have difficulty
   finding a good setting on the boogie which allows the flexibility I want.
   The sounds from the two channels are not independent.  To get a heavy
   distorted sound from the lead channel, I have to put some distortion
   in the 'clean' channel.  Not really what I have in mind.  In the
   configuration I have now, I can use the GSP to switch the boogie in
   or out of the chain via the MIDI pedal.  This way I can get a range from
   solid-state clean to tube scream via MIDI (MRP).

   The only thing useful I use the SPX for is pitch detuning.  I spend a lot
   of time just playing along with CDs and for the odd song (Satch's "Friends"
   or Extreme's "Rest in Peace" are recent tunes that come to mind) where
   all strings are tuned 1/2 step flat, it makes life a lot easier.  The tone,
   once detuned, is awful but it gets me though figuring a song out.  I'd
   never play for someone else that way.

   I am curious about your comment on the Hush.  Do you feel that way about
   Noise Gates in general, or just Rocktron's implementation?

>   The only thing useful I use the SPX for is pitch detuning.  I spend a lot
>   of time just playing along with CDs and for the odd song (Satch's "Friends"
>   or Extreme's "Rest in Peace" are recent tunes that come to mind) where
>   all strings are tuned 1/2 step flat, it makes life a lot easier.  The tone,
>   once detuned, is awful but it gets me though figuring a song out.  I'd
>   never play for someone else that way.
    
    Gross!  Why don't you just get a tape deck with a pitch control on it? 
    Still sounds a little funny, but not nearly as bad as using an SPX90
    pitch shift function.  Then you just tune the tape to your
    instrument.
    
    Greg

    
    Greg,
    
    You mean you *speed up* Nuno's solos to figure them out? ;-)
    
    
    guy

>    You mean you *speed up* Nuno's solos to figure them out? ;-)
    
    That's right, Guy.  That Nuno's chops are just so sorry that I just
    can't manage to keep my level of interest up enough to learn his songs
    unless I speed 'em up quite a bit.
    
    Greg

    
    Yeah, I have that problem too, Greg.....
    
    
    
    
    ....NOT!!! 
    
    ;-)
    
    
    guy

    >I think I disregarded it because I have difficulty finding a good
    >setting on the boogie which allows the flexibility I want. The sounds
    >from the two channels are not independent.  To get a heavy distorted
    >sound from the lead channel, I have to put some distortion in the
    >'clean' channel.  
    
    Sounds familiar.  We, in here, refer to this as "the classic boogie
    problem".
    
    By the way, don't laugh at the idea of speeding up to figure out
    parts.  
    
    It works EXCEPTIONALLY WELL for figuring out bass parts that are buried
    in the mix.  Speeding them up seems to bring them right up to the front
    of the mix and the higher pitch makes the bass easier to hear.
    
    I do this quite a lot.
    
    It's kinda funny cause I have a dubbing deck with a 2x capability.  
    
    To figure out the bass parts, I need THREE tapes: 1 with the material
    I'm trying to learn, a scratch tape, and one tape to record on.
    
    I dub at 2x speed to the scratch tape, and RECORD the output of the
    deck while it's doing that onto another tape and THAT tape is what
    I use to learn the part!  

    >It's kinda funny cause I have a dubbing deck with a 2x capability.  
    >To figure out the bass parts, I need THREE tapes: 1 with the material
    >I'm trying to learn, a scratch tape, and one tape to record on.
    >I dub at 2x speed to the scratch tape, and RECORD the output of the
    >deck while it's doing that onto another tape and THAT tape is what
    >I use to learn the part!  
    
    Yo, db!
    
    I take it you sold your four-track, since the average four-track
    running at 3-3/4" will play the tape at double speed no sweat.  The
    Tascam 424 is even cooler since you play tapes at either half or double
    speed.
    
    						Brian

    re: speeding up to figure out bass parts
    
    Do you do this with Jaco's lines, by any chance?
    
    Dave

    I'm sure he does, Stu Hamm and Les Claypool's too.
    
    Greg