Is my GR-33 hosed or is my GK-3 hosed (or both) ?

Started by concordal, February 22, 2018, 03:43:08 PM

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concordal

Just got a GR-33, which appears to be pristine.  I re-wired a GK-3 pickup for "reverse mounting" as described at
https://www.vguitarforums.com/smf/index.php?topic=3365.0

Problem?  The output volume is extremely low - on every patch.

So I adjusted the Input Sensitivity ('PICKUP SENS').  But **even at level 8** the maximum sensitivity I can get looks like the picture below for every string (except my SENS is to 8).  The pic is from the GR-33 User manual and has the caption "Sensitivity Low".
 
     Pic from GR-33 User Manual
 
To check that the modded GK-3 and cable are OK, I tried them on a GR-55.  The volume is good and all patches work correctly with GK PU Direction set to "NORMAL"
 

Here are a few things I've already tried / checked:

- Checked that GK-3 is setup correctly:  string to PU clearance is 1 mm when string is pressed at last fret.  And the divided pickup is less than 20 mm from the bridge

- Verified that the GK-3 switch is set to the "Mix" position.

- Verified that the GR-33 expression pedal is toe down.

- Cleaned both the GK-3 jack and the cable plug with Caig De-Oxit.

- Did a Factory Reset.

- Updated GR-33 firmware to the latest, Ver. 1.03

Is there anything else I can try to increase the volume / sensitivity?   Is the GR-33 hosed  OR  is the GK-3 hosed OR both??   Any advice appreciated.

CodeSmart

#1
Have you been able to verify that there's +7V and -7V available at the GR-33 GK connector?
(I'm thinking a damaged voltage regulator)

Pin 13 = -7V
Pin 12 = +7V
Shield/casing = Ground, 0V

Pinout here:
http://johnp.net/projects/guitar-synth/roland-pinouts.html

But I got more gear than I need...and I like it!

Elantric

Quote from: CodeSmart on February 25, 2018, 12:27:00 PM
Have you been able to verify that there's +7V and -7V available at the GR-33 GK connector?
(I'm thinking a damaged voltage regulator)

Pin 13 = -7V
Pin 12 = +7V
Shield/casing = Ground, 0V

Pinout here:
http://johnp.net/projects/guitar-synth/roland-pinouts.html

And barely anyone mentions the fact that you can easily permanently damage your GK processor if you are too casual and attempt to connect the GK 13 cable while the gear is powered ON. Several have fried their Roland Boss processor by attempting to  force a misaligned DIN 13 plug = electrical short the +/-7VDC POWER on pins 12 & 13

gumtown

How does the normal "Guitar" output compare?
I was testing my GR-33 last week before I put it up for sale, and noticed the output is a bit lower than a GR-55.
At most it seems to output at instrument level, and the Phones are very quiet.
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

concordal

codesmart and gumtown:  Many thanks for the suggestions.

QuoteHave you been able to verify that there's +7V and -7V available at the GR-33 GK connector?

Yes,   All OK.  Pin 13 = -7V   and   Pin 12 = +7V


QuoteHow does the normal "Guitar" output compare?
The volume levels are the same comparing Normal vs Synth: both very low, even at full volume on the GR-33 and on the GK-3.   To be sure that my ears weren't being fooled, I compared the Input Sensitivity ('PICKUP SENS') reading on all six strings of Normal guitar vs synth; the levels are the same.

Any other suggestions appreciated.




concordal

I would really appreciate any other thoughts from vguitar members.

Since the modded GK-2 works nicely on a GR-55, I  think the low volume problem (or more correctly low Input Sensitivity) is with the GR-33 unit itself.  I'm not an electronics tech but I am a solder jockey and am quite willing to heat up the soldering iron if anyone has an idea of what to try.  ???

Thanks for any suggestions.

gumtown

I can't add much more except that my GR-33, compared to y GR-55, put out a very low volume level too.
I find the GR-55 level knob is adjustable from 0 to Line Line, with instrument level at half way.
The GR-33 output knob went from 0 to instrument level at maximum, even quiet through headphones too.
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

admin

#7
QuoteThe volume levels are the same comparing Normal vs Synth: both very low, even at full volume on the GR-33 and on the GK-3.   To be sure that my ears weren't being fooled, I compared the Input Sensitivity ('PICKUP SENS') reading on all six strings of Normal guitar vs synth; the levels are the same.

Any other suggestions appreciated.

If you read the GR-33 Manual you would understand the GR-33 outputs Instrument level Audio - or Line Level

Must set OUTPUT LEVEL to your desired level ( Page 19)


GR-33 FAQ
https://www.vguitarforums.com/smf/index.php?topic=14682.0


GR-33 Manual
http://cdn.roland.com/assets/media/pdf/GR-33_OM.pdf

http://lib.roland.co.jp/support/en/manuals/res/1811448/GR-33_e2.pdf


Observe Roland recommends feeding GR-33 Output into Instrument Level inputs  - but change the Output Mode to Line Level will allow you to feed -10db Line Level inputs

admin

#8
QuoteJust got a GR-33, which appears to be pristine.  I re-wired a GK-3 pickup for "reverse mounting" as described at
https://www.vguitarforums.com/smf/index.php?topic=3365.0

Problem?  The output volume is extremely low - on every patch.

So I adjusted the Input Sensitivity ('PICKUP SENS').  But **even at level 8** the maximum sensitivity I can get looks like the picture below for every string (except my SENS is to 8).  The pic is from the GR-33 User manual and has the caption "Sensitivity Low".
 
     Pic from GR-33 User Manual
 

The GK-3 has lower signal level vs older GK-2A

If you are handy, you can solder and swap  the GK-3 opamp amp gain set resistors for the same values used on GK-2A to increase the  GK-3's output gain,, to accommodate older GK 13 pin gear that expects the higher GK-2A signal levels


http://www.learningaboutelectronics.com/Articles/Op-amp-gain-calculator.php


see Schematics
  https://www.vguitarforums.com/smf/index.php?topic=73.0


GK-2A



GK-3


GK-2A Opamp Gain Sensitivity
----------------------------------
Rin = 8.2K
Rfeedback  = 200K
Gain: 24.39


GK-3 Opamp Gain Sensitivity
----------------------------------
Rin = 820
Rfeedback  = 10K
Gain: 1.01

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