KPA with GR55

    I once owned a GR55. Great bit of kit but like everything it has its limitations.
    At the time my intention was to use the guitar modelling side of it (through the guitar outs) with a Marshall AFD, but the combination of a noisy guitar only output (on the GR55) and the very dirty nature of the AFD, which doesn't do clean, meant it didn't work as I hoped and I moved it on and went back to my Roland GR30.
    I was wondering if anyone (Are you there Elantric?) has tried the GR55 with the KPA.
    Im very keen on getting as much as I can out of as little gear as possible especially if it means quick set up and break down time at gigs.
    For those who don't know, the GR55 has guitar modelling, including modelled guitar tunings, 2 PCM synth sounds at a time and the usual Boss COSM modelling and fx. The guitar models and straight guitar can be output without fx or synth sounds through a specific 'guitar out' which would typically be sent to the KPA input. The other 2 stereo outputs would typically carry the synth sounds to the pa.
    Any combination of straight guitar, modelled guitar and 2 PCM synth sounds can be played at once.
    The combination of guitar modelling and PCM synth sounds (GR55) and the unbeatable KPA amps/ fx seems like a huge palette, esp as the GR55 and GK3 switches and continuous could be used in conjunction with a couple of footswitches into the KPA in place of a separate foot controller.
    If anyone with both units has the time to do some clips of the GR55 guitar models with the KPA amp models it would be great. As I write this Im convincing myself to delve back into the GR55.............

    On my VguitarForums - member "Musicman65" wrote about his GR-55 and KPA experience :


    http://www.vguitarforums.com/s…ic=3331.msg38897#msg38897


    Quote

    First impression on the Kemper is very favorable. The amp sounds are very dynamic with waaaay more depth and feel than Roland or Line6 IMHO.


    l connected the GR-55 guitar out to the KPA input and tested some Roland COSM modeled Tele, LP sounds and alternate tuning...works great! Next step is to get the midi Patch Changes on the GR-55 to change patches on the KPA when I have the time.


    I wish the KPA had separate eq on the 1/4" stereo and XLR outs so I can normalize my stereo FRFR amp and FOH feed. Parametric eq would be even better. I suspect the two share the same audio circuit. There's a nice cavity in the back to house an external mini eq if needed.



    Bill Ruppert replied:

    Quote

    {On the KPA} There is a separate 4 band EQ for both the monitor out and master out....

    sheguitarplayer,


    Musicman65 from VGuitarForums here.


    I've been out of town for a week so no more testing. I am back and will get back on my GR55 / KPA testing, One thing I did notice was a very small loss of fidelity on the magnetic pups going through the GR55. This could be due to several things including a buffer circuit in the GK interface to send it via 13-pin. I'm thinking its a slight high end roll-off and an eq tweak can easily compensate. Humbucker users may never notice. The modelled guitar tones sound great. Alt tunings and polyphonic effects like the poly whammy pedal are sooo cool with the KPA's surreal tubey-ness.....very nice.


    I will pay more attention to noise levels and other issues and report back. MIDI program change to get the KPA to follow theGR55 and also how to mix KPA and GR55 stereo signals are next. A mini 4 channel mixer will be required.


    bd

    After several hours of trying to get the heavy hiss to go away...I give up. The Roland GR55 has cheap circuitry. The signal to noise on the guitar out is so great, its unusable with amp profiles that have any gain. What a pity. Why even include the guitar out jack with such a crappy lo-fi signal?


    The GR55 / Kemper combo would have been perfect....

    sheguitarplayer,


    GOOD NEWS! I got so pissed about the crappy signal to noise ratio on the GR-55 Guitar Out jack, I took my GR-55 apart and got my o'scope out and went noise hunting. Turns out the noise floor on every output is the same, identical...about 1mV avg pk-pk. It's on everything, headphones, L/R mains,,,,and guitar out. The issue is that the rest of the outputs have gain so the output signal is large in comparison to the noise floor....but the guitar out is just buffered with no gain so its a smaller signal. That makes the signal-to-noise ratio worse than with the main outs or headphones. In fact, the headphone out may be the best.....hmmm?


    Sooo...I decided to use the L/R Main outs into the Return/Alt Return jacks on the KPA and set the first stomp to Stereo Loop. This injects the GR55 into the KPA signal chain just after the front guitar input and noise gate, It works great. Quite too. You lose the noise gate (and maybe the Clean / Dist Sense?) but gain a full guitar modeler with alt tuning, tons of effects, all the Roland Goodness of the VGuitar setup.


    Now, here's the cool part. After saving your KPA profile with Stereo Loop enabled in the Stomp section, disable the stomp and save a second rig with Stereo Loop in the X slot of the effects section. Now dial up a PCM synth tone and it's inserted in the mix AFTER the Amp section....nice and clean. With Stereo Loop in either Pre (Stomp) or Post (Effects) position, you get a gain and mix control. Use them to blend GR-55 and normal guitar input if you still have a non-gk guitar you want to use....or decide to make the mod below.


    Tomorrow, I am installing a REAL, UNBUFFERED GUITAR OUT jack in my GR55. I will pick off the signal from the 13-pin jack's terminating board. This will give me a noise free guitar out just like my VG-99 has. Then I'll have tons of options via KPA front jack and Stereo Loop.


    Next is MIDI setup so KPA rigs are changed via GR55 with correct pre or post Stereo Loop settings depending on what tones I want, ie: KPA with straight guitar, synth sounds, GR55 alt tuning, GR55 acoustic, modeled guitar, etc....I am super excited this is gonna work.


    bd

    Problem solved...I installed an extra output jack that taps into the guitar pickup signal before buffering. The noise is gone and tone is restored.


    The GR55 now is a very nice polyphonic effects and footcontroller for GK equipped users.



    bd

    sheguitarplayer,


    the mod was super simple. Drilling the hole was the hardest part if you know how to solder. You could make a splice in the pin-7 white wire and red wire if soldering on the circuit board makes you nervous. See the pics on the link below for more info.


    More pics with noise measurements are found here:
    http://www.vguitarforums.com/smf/index.php?topic=5456.25


    [Blocked Image: http://www.cruzerrocks.com/GR-55/IMG_20120410_203526.jpg]