GR-55 - Using the GK volume to control the COSM amp

Started by jwhitcomb3, January 17, 2014, 11:29:19 AM

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jwhitcomb3

I like using my guitar's magnetic pickups through the GR-55 COSM amp models. Early on, I tried cross-fading the amp gain and amp level, for example, controlled by the EXP pedal, to move from a clean to a medium-high gain sound, but wasn't very satisfied with the results. Mostly, I found I could get a good clean sound, or a good crunchy sound, but it didn't sound good across the range. Usually a good clean sound led to a shrill crunchy sound, and a good crunchy sound led to a a thin and dull clean sound.

After much experimentation, I've come up with the following patches that are a big improvement. They use the GK volume control to crossfade multiple amp controls. The goal is for the perceived volume level not to change much across the whole GK Vol sweep range, but to make the amp character change from clean(ish) to crunchy, with a wide range of in-between tones. Depending upon the patch, the amp mid, treble and presence may be crossfaded along with the amp gain and level. I find this evens the tone across the range.

While the main point of these patches is changing the character of the COSM amp with the GK Vol, there are several other useful controls

  The CTL pedal is set up for tap tempo
  EXP pedal controls the delay level.
  EXP SW toggles a MOD block tube screamer distortion
  GK S1 toggles the MFX compressor
  GK S2 toggles the amp solo switch

The cool thing about this setup is how well the COSM amp responds to the guitar's volume/tone controls and pickup selector. Even when you have the GK Vol pegged, rolling off the guitar volume and/or tone controls responds much like a real amp would.

The four patches attached use the MATCH (DRIVE) model, the Clean Twin model, the Pro Crunch model, and the Tweed model (what can I say, I'm a Fender amp guy).

Some caveats: This setup is very sensitive to how the System/GK Settings/Norm PU gain is set. For example, on my Carvin HF2S, the Norm PU Gain is set to -3 dB. My MIM Roland Ready strat with stock pickups is set to +2 dB. If you hear much breakup when the GK volume control is minimized, try reducing your Norm PU Gain. On the other hand, if you aren't getting a full-out overdriven tube amp sound when the GK Vol is pegged, try increasing your Norm PU Gain.

The other thing is, like any amplifier, the tone control settings will need to be modified based on your guitar, your pickups, and your personal taste. Since I put these patches together using a guitar with medium bright humbucker pickups, I have to roll back the tone control on my Strat to tame the high end. Just remember, if you want to change the tone controls on the amp, make sure you make the adjustment in the assigns section if the amp control is tied to an assign (because otherwise your edits will be masked). 

This is tweaky stuff, but I like having a whole range of tones at my disposal within a single preset.

Please let me know how these work for you, and please post any modifications you come up with.

Elantric

#1
Thanks for sharing! This path for GK-Vol assignment for COSM Amps in GR-55 one of the secrets to getting good tone with GR-55 - although know its typically incompatible with the US-20 A/B selector, should you ever expand your 13pin system. 

jwhitcomb3

Thanks for the tip on the US-20, Elantric. Frustrating that Roland doesn't upgrade their accessories to keep up with their main products.

Dewittian

I may be thinking back to my old GR20 but do I have to route my 1/4 out jack back into the GK unit or is this setup controlled by the 4th tone generated after the data becomes digital.  Some of this is pretty new to me so I'm not even sure how the GR55 can get the sound of pickups not even plugged into it.  I know this may sound like a dumb question but should I use a cord to take the guitar out to the GK in?  It sounds like your patch uses the original guitar signal.  If so then did you use the front or back to transition from clean to harsh tones?
Gear:
Laptop windows 10
GR55
Tascam US1800
Ibanez with GK3 pickup and M-Audio Keystation

datsunrobbie

Assuming an external GK pickup, then yes, you must connect the output jack of the guitar to the input jack on the GK controller wart to pass the magnetic pickup signal to the GR-55.

jwhitcomb3

These patches are set up to use the signal from your guitar magnetic pickups as an input, so if you have an externally mounted GK pickup, you'll need the patch cable between your guitar's output to the GK input.

Of course, you can always edit the patches to use a COSM electric guitar as the input instead of the magnetic pickups. I have done that with other patches that I will upload if you are interested. Those patches roll the COSM pickup volume off at the very bottom of the GK Vol range and let you use the S1 button to toggle between two pickup settings. But I digress.

I don't understand your question about using the front or back. The clean end of the range corresponds to the end of the GK volume that would be 0 on a normal guitar volume control, and the crunchy end of the range corresponds to a 9 on a normal volume control. Lots of cool tones in between.

I've continued tweaking these patches and experimented with other amp models than those I've uploaded here. I find that each COSM amp model has something of a sweet spot, or more precisely, a sweet range, and the trick here is to set up the patches so the GK Vol control sweeps across this sweet range. The sweet range is wider for some amp models than for others, and your results will depend upon the output level of your pickups and how you've set up the trim levels in the GR system settings.

jwhitcomb3

I've been tweaking these patches, and here are the latest iterations. S1 now brings in an electric piano and bass (on the low E and A strings), except on the Boogie patch.

There are also a couple patches here that apply this technique to COSM electric guitars.

imerkat

I use the modeling tone's pickup level with amp gain level inversely with the GK Volume.

jwhitcomb3

Quote from: imerkat on February 24, 2014, 06:39:23 AM
I use the modeling tone's pickup level with amp gain level inversely with the GK Volume.
Yep. That works great for COSM patches. Not so much for the normal pickups.  :)

Dewittian

I've seen GR55 youtube videos where some of the patches they play (out of the box) have a good blend between clean and distortion using only their pick.  I haven't found any patches like it yet so if anyone knows of some or a link please let me know.

I think the volume changes between clean and distortion are more perceived than actual.  It always sounds fuller therefore louder when I have distortion on a guitar track.  It takes up more frequencies and the lack of clean transients to a lower level found in the clean tones makes us perceive it as louder when it's just longer.  I'd love to have a patch that normalizes this affect.  I like playing clean then using only my pick getting the tube affect without the added volume but I find range is a problem even when I use the just the speakers or pre-amp level to create the distortion.
Gear:
Laptop windows 10
GR55
Tascam US1800
Ibanez with GK3 pickup and M-Audio Keystation

admin

The factory GR55 patches do not reveal the details of the COSM Amp modeling.
Try these user created patches.

www.vguitarforums.com/smf/index.php?topic=3684.0