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Author Topic: More gain from Crate 120  (Read 410 times)

shaniac

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More gain from Crate 120
« on: December 24, 2018, 11:15:09 AM »
Hi all,

I've a Crate GTD120 (same schematic as the Flexwave, different DSP) and I'm trying to eke a little more gain (15-20%) out of the 'overdrive' section. Since they cascade into one another I'm not sure exactly which component would control the gain available at that stage.

Would it be as simple as changing P1 (Overdive Gain pot) or R11 or R14? Or would changing those likely result in oscillations from the op amp? Any help would be appreciated.

Jazz P Bass

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Re: More gain from Crate 120
« Reply #1 on: December 24, 2018, 12:37:40 PM »
I  would try changing R76 to a lower value.
(coming off of the OD Lvl wiper.)

phatt

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Re: More gain from Crate 120
« Reply #2 on: December 25, 2018, 06:41:37 AM »
I  would try changing R76 to a lower value.
(coming off of the OD Lvl wiper.)

Hi Jazz,,
I'm scratching my head about R76, surely that will just effect the Hi cut effect of C52 above it? Or have I had too much to drink.  :lmao:

Maybe if Shaniac could clarify if he wants more *Distortion* or more *Volume* from the hot channel we can help better.

I know that I've had a few amps where the hot channel has to be maxxed out to keep up with the clean channel volume.
This buggers up the balance between the two channels which limits the usefulness of an otherwise good rig.
Phil.


Jazz P Bass

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Re: More gain from Crate 120
« Reply #3 on: December 25, 2018, 11:39:36 AM »
Yeah, I really did not study the circuit for too long.

I do believe the OP is asking too much from a Forum.

shaniac

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Re: More gain from Crate 120
« Reply #4 on: December 26, 2018, 06:33:13 PM »
Maybe if Shaniac could clarify if he wants more *Distortion* or more *Volume* from the hot channel we can help better.
Sorry, more distortion. The amp starts to get to a nice chuggy quality right as the gain knob is maxed out and I'd like a little more of this without having to engage the lead circuit which only has a (not particularly useful) "shape" knob.
I know that I've had a few amps where the hot channel has to be maxxed out to keep up with the clean channel volume.
This buggers up the balance between the two channels which limits the usefulness of an otherwise good rig.
Phil.
There's a bit of this going on too.

phatt

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Re: More gain from Crate 120
« Reply #5 on: December 27, 2018, 07:04:17 AM »
You could try;  R43 around IC3A is 22k,, try 47k.
Keep in mind that will also raise the output level of the high Gain Channel as well.  Worth a try.

To raise the Volume level of *Odrive only* you will have to tweak around the ODrive level pot. Try bridging R72 with a wire link and if not enough volume lift you could temporarily lift one end of R76 (10k) as well, though that will alter the tone a bit which may or may not be good but suck it and see how it sounds.

Be careful with de-soldering parts as some of the PCB's have very tiny solder pads and very thin tracks that are easy to wreck.  :'(
Phil.

shaniac

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Re: More gain from Crate 120
« Reply #6 on: December 29, 2018, 11:28:53 AM »
You could try;  R43 around IC3A is 22k,, try 47k.
Keep in mind that will also raise the output level of the high Gain Channel as well.  Worth a try.

To raise the Volume level of *Odrive only* you will have to tweak around the ODrive level pot. Try bridging R72 with a wire link and if not enough volume lift you could temporarily lift one end of R76 (10k) as well, though that will alter the tone a bit which may or may not be good but suck it and see how it sounds.

Be careful with de-soldering parts as some of the PCB's have very tiny solder pads and very thin tracks that are easy to wreck.  :'(
Phil.

Coolio. Got a show tonight. I'll mess around and see if I notice any difference next week t practice. I took the DSP out as it never functioned properly and I noticed that has already made it a bit louder, but not more distorted.

 

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