What is a subsonic filter for GK 13 pin processor used for?

Started by Elantric, March 22, 2016, 12:48:30 PM

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Elantric

QuoteWhat good is a subsonic filter for GK 13 pin processor use?

The subsonic filter addresses a specific problem and may benefit GK-13 gear users with Piezo Hex pickups. (RMC, Graph-tech Ghost, Fishman, LR Baggs)

The Subsonic filter board for GR-55 addresses:

QuoteGR-55 COSM GR-300 patch has too much low frequency rumbles and noises anytime I touch the guitar bridge, and Guitar to PCM and Guitar to MIDI has much mistracking  / wrong notes.

To test if you have the problem, try this patch on the GR-55 "01-3  GR-300 Ctl:+1Oct "  - which uses the COSM Model of a 1981 Roland GR-300 Guitar synth ( Robert Fripp, Pat Methany tone)
Two separate versions of this RMC filter board (with different cutoff frequency filters ) are available for Guitar or Bass. Its essentially similar to the old "Rumble Filter" switch on old phonograph stereos -   RMC OPT-01 subsonic filter board removes low frequency content using six separate active 4 pole filters. 




RMC OPT-01 - GR-55 Internal Subsonic Filter board
https://www.vguitarforums.com/smf/index.php?topic=3236.0
https://cdn11.bigcommerce.com/s-c9sjki2/images/stencil/1280x1280/products/2482/4401/OPT-01_C__72615.1527876839.jpg?c=2&imbypass=on


PRIMOVA - GKFX-21 Subsonic Filter Project
https://www.vguitarforums.com/smf/index.php?topic=15681.0


DR_JONESS - Filter/Buffer - GR Subsonic Filter w/ 2 Aux Inputs +Efx Loop
https://www.vguitarforums.com/smf/index.php?topic=9692.0

gearhound22

Is there a list anywhere which devices do and don't have them?

I know GR33 has some filtering.....GR55 has none

Does the Axon ax50/100 units have them and the new Boss SY-1000?

admin

Quote from: gearhound22 on February 25, 2020, 10:50:59 PM
Is there a list anywhere which devices do and don't have them?

I know GR33 has some filtering.....GR55 has none

Does the Axon ax50/100 units have them and the new Boss SY-1000?

Remember a Sub Filter is specifically targeted to resolve mistracking and noise issues for Piezo PU users

Use a GK-3 and no sub filter required

gearhound22

Quote from: admin on February 26, 2020, 02:11:58 AM
Remember a Sub Filter is specifically targeted to resolve mistracking and noise issues for Piezo PU users

Use a GK-3 and no sub filter required

In this case would be for Lr Baggs/RMC piezo ...I'm kicking myself finding out about the primova GK splitter with the filter now :(

I'll be using the piezo into an axon ax100 and the sy-1000 when it arrives in Canada.
Thats why I was curious if these two devices have a filter built in :)

drjoness2001

I do not have the schematics for the SY-1000 (duh!) but when I opened the unit up, I saw what looks like analog filtering for the input:

https://www.joness.com/gr300/SY-1000.htm#interior

The SY-1000 may not need an external filter

gumtown

Quote from: drjoness2001 on February 26, 2020, 06:44:54 PM
I do not have the schematics for the SY-1000 (duh!) but when I opened the unit up, I saw what looks like analog filtering for the input:

https://www.joness.com/gr300/SY-1000.htm#interior

The SY-1000 may not need an external filter
Any filtering would have to be in the DSP or programmable,
because how would the filter work otherwise when a Bass is connected.

Two different filter ranges would be required.
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

szilard

Quote from: gearhound22 on February 26, 2020, 12:28:00 PM
In this case would be for Lr Baggs/RMC piezo ...I'm kicking myself finding out about the primova GK splitter with the filter now :(

I'll be using the piezo into an axon ax100 and the sy-1000 when it arrives in Canada.
Thats why I was curious if these two devices have a filter built in :)
From my experience the subsonic filter doesn't help with midi tracking (gtr2midi) on Roland devices so I'm not sure it would do anything for an Axon. When using Roland's signal processing touching the strings/bridge/tremolo arm in some situations generates a static like noise. RMC's SS filter didn't fix the problem for me on the VG 99, but improved the situation. The static noise is there on my SY-1000 (on some patches) and I have an SS filter on order - I'll report on the results when I get it. I've switched to using a guitar with a gk2 playing with the 1000.

admin

Quote from: Nobulusprime on March 10, 2020, 03:31:45 PM
So I'm experiencing some odd behaviour with 98 Godin LGXT which uses an LR baggs piezo. There is a lot of erratic triggering on the Osc synths which can be minimised slightly with some adjustments to the levels but it's still poor. Also with the acoustic 12 string sounds horrendous, as it warbles pitch wise on both octave and unison strings, regardless of what level each string is or low cut/high cut or which pick up I select. However on the VG99 the 12string sounds perfectly ok, with the same guitar and lead... When I use my GK 3 pick up guitars these are much better. Any ideas? I really think Boss/Roland need to look closely at supporting the SY1000 developments and improvements asap. There are a number of issues that need looking at which I'm hoping they can resolve.

On that old Godin with LR Baggs Piezos  you WILL need a separate GK 13 Sub Filter for use with SY-1000

What is a subsonic filter for GK 13 pin processor used for?
https://www.vguitarforums.com/smf/index.php?topic=17667.msg125868#msg125868


Remember Roland / Boss's 1st Priority is design GK-Processors to operate around their own GK 13 pickup -
the Roland  GK-3


Its truly a band aid / afterthought to provide support for Piezo pickups ,
and not all Piezo pickups and their respective multi-channel preamp boards are created equal !


To address GK Piezo user's issues of low frequency Thumps and random glitch notes,
in 1997 Richard McClish at RMC Pickups developed improved bandpass filter Component Change List
for the original VG-8

VG-8 SUBSONIC SENSITIVITY REDUCTION MODIFICATION
https://www.vguitarforums.com/smf/index.php?topic=13078.0


In 1999 a Similar Mod was designed for VG-88
https://www.unfretted.com/extras/unfretted-archive/vg8-vg88-mods/


In 2007 Upon release of the VG-99 - to benefit Piezo users I loaned my brand new VG-99  to Richard McClish and he developed the

RMC V9SF-001 - VG-99 Internal Subsonic Filter board



Later a separate version with different filter frequency points for Bass Instruments was developed for VB-99

RMC V9SF-001B Sub Filter board for Roland VB99 (Review)
https://www.vguitarforums.com/smf/index.php?topic=3063.0

IN 2011 I once again loaned my new GR-55 to Richard to develop the

RMC OPT-01 - GR-55 Internal Subsonic Filter board
https://www.vguitarforums.com/smf/index.php?topic=3236.0

Later Dr Wayne Joness developed limited production runs of his own external inline GK 13 pin Sub Filters
https://www.vguitarforums.com/smf/index.php?topic=9692.0



and lately CodeSmart @ PrimovaSound has offered the



PRIMOVA - GKFX-21 Subsonic Filter Project
https://www.vguitarforums.com/smf/index.php?topic=15681.0
http://primovasound.com/gkfx_1.html


Shingles

Quote from: gearhound22 on February 26, 2020, 12:28:00 PM
In this case would be for Lr Baggs/RMC piezo ...I'm kicking myself finding out about the primova GK splitter with the filter now :(

I'll be using the piezo into an axon ax100 and the sy-1000 when it arrives in Canada.
Thats why I was curious if these two devices have a filter built in :)

I don't know what analog filtering the Axon AX100 has on the front end.
I do know that it needs no extra filtering for excellent guitar-to-MIDI tracking of LR Baggs piezos found on my 20 year old Godin LGXT. I am fairly sure the same goes for RMC piezos on the LGX-SA.
Nik
--------------------------------
Tonelab, VG99, Axon AX100, EDP, Repeater
Godin, PRS, Crafter and Roland guitars
Center Point Stereo Spacestation V3

Dalai_llama

Quote from: Shingles
I don't know what analog filtering the Axon AX100 has on the front end.

None. The Axon analyses the early transient produced by the action of the pick on the string. Filtering those disable the Axon altogether. For that reason, in the mid-90s LR Baggs equipped Godins had to have their boards replaced, as they filtered transients. Blue Chip produced and sold such replacements.

In the Axon, selecting PIEZO as the source changes input sensitivity. If I recall correctly, the FINGER PICK setting, introduces some filtering and disables the pick zone feature.

Quote
I do know that it needs no extra filtering for excellent guitar-to-MIDI tracking of LR Baggs piezos found on my 20 year old Godin LGXT. I am fairly sure the same goes for RMC piezos on the LGX-SA.

Absolutely. Axon tracking is not at all affected with subsonic filtering. I tried it with a Wayne Joness Filter/Buffer, zero difference. I've used the Axon with RMC Poly-Drive 1 from 2004 (Brian Moore guitars), Poly-Drive 2 & 4 for acoustic guitars, and Poly-Drive X past 2011 -- which has subsonic filtering -- and it tracks superbly. The combination of Axon + nylon string flatpicked with Poly-Drive 4, which is the most likely to produce glitches (due to PD-4's dynamic range), works perfectly well for me.

Shingles

Quote from: Dalai_llama on April 28, 2021, 04:44:57 AM
None. The Axon analyses the early transient produced by the action of the pick on the string. Filtering those disable the Axon altogether. For that reason, in the mid-90s LR Baggs equipped Godins had to have their boards replaced, as they filtered transients. Blue Chip produced and sold such replacements.

In the Axon, selecting PIEZO as the source changes input sensitivity. If I recall correctly, the FINGER PICK setting, introduces some filtering and disables the pick zone feature.

Absolutely. Axon tracking is not at all affected with subsonic filtering. I tried it with a Wayne Joness Filter/Buffer, zero difference. I've used the Axon with RMC Poly-Drive 1 from 2004 (Brian Moore guitars), Poly-Drive 2 & 4 for acoustic guitars, and Poly-Drive X past 2011 -- which has subsonic filtering -- and it tracks superbly. The combination of Axon + nylon string flatpicked with Poly-Drive 4, which is the most likely to produce glitches (due to PD-4's dynamic range), works perfectly well for me.

So, first you say that Axon tracking gets screwed up by input filtering.

Then you say that Axon tracking does not get screwed up by input filtering.

?

Fingerpick mode in Axons disables the transient pitch detection, leaving only zero crossing pitch detection as found in Roland guitar to MIDI systems.
Nik
--------------------------------
Tonelab, VG99, Axon AX100, EDP, Repeater
Godin, PRS, Crafter and Roland guitars
Center Point Stereo Spacestation V3

Dalai_llama

Quote from: Shingles
So, first you say that Axon tracking gets screwed up by input filtering.

First I say that filtering transients altogether (like Godins used to do) disables the Axon since it uses them -- hence why Blue Chip had to sell a board specifically for Multiacs. This topic was widely discussed at the now defunct Midiguitar group on Yahoo and Andras Szalay himself explained this situation and why he had to come up with a replacement board for those guitars. I specifically remember him saying that it was a "bad surprise".

Quote
Then you say that Axon tracking does not get screwed up by input filtering.
?
Fingerpick mode in Axons disables the transient pitch detection, leaving only zero crossing pitch detection as found in Roland guitar to MIDI systems.

Then I say that -- and pardon my "some filtering" poor wording -- that fingerpick mode, like you said, disables the pick zone by disabling transient detection as you describe, and therefore behaves much like a Roland system as you note. Here the Axon is using the signal in steady-state AFTER it was input with all transients, even if they are not to be used. If my recollection is correct, fingerpick mode was introduced in later models. (I'm not an Axon encyclopedia so I might be wrong here.)

The Axon does not "get screwed" by subsonic filtering as provided by the Primova box and RMCs boards -- and I didn't say that in my message. Quite the opposite. The attenuation of lower frequency sounds provided by subsonic filtering does not fully eliminate transients and the Axon is happy with that. Conversely, the rumble that the lack thereof produces -- and causes mayhem in Roland systems -- also enters the Axon, but since it's detecting transients, it does not affect its performance to the naked ear.

I never tried filtering transients and enabling fingerpick mode to see if the Axon would work. Looking into that then as now makes no sense to me, time- and resource-wise.

Hope this clarifies my earlier post.

guitfiddleblue

I know I'm coming to this thread much later, but did want to share that the Primova GKPX-4F (the "F" is for "Filter") helps Piezo pickups with the extraneous noise on a Boss SY-1000 - and it has 4 outs, which is cool.