RMC OPT-01 - GR-55 Internal Subsonic Filter board

Started by imall41, February 21, 2011, 05:24:58 AM

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imall41

Update:  I installed the RMC opt-1 and it made all the difference in the world. I made some videos of installation and demo to compare. Also made a series of videos of my final settings in th GR-55 calibrated for my Godin XTSA. Hopefully this will help some having the same problems I did.




https://stores.soundislandmusic.com/cart.php?suggest=cc0f302e-21dd-4eb5-87f4-1fbc2517954d

The RMC OPT-01 subsonic filter board for GR-55 addresses a specific problem and may benefit ALL GR-55 users with Piezo Hex pickups. (RMC, Graph-tech Ghost, Fishman, LR Baggs)

The Problem the RMC OPT-01 subsonic filter board for GR-55 addresses:

Quote GR-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. 

Contact RMC for details

info@rmcmusic.com

RMC Pickup Co.
1739 Addison #15
Berkeley CA 94703




Important NEWS! June, 24, 2011

The RMC Subsonic Filter for GR-55 (G5SF-001) is now called the "OPT-01 Subsonic Filter for GR-55"

Details here:
https://www.vguitarforums.com/smf/index.php?topic=3236.msg27687#msg27687
------------------------------------------------------------------------------------------------------------
old post below:
----------------------------------------------------------------------
Richard McClish (RMC) is now developing a subsonic filter to help remedy the  piezo noise issues,
we are experiencing with the GR-55.

                Richard McClish Wrote,

"I'm presently developing an in-line 13-pin subsonic filter,
since the GR-55 seems to have the same tracking issue with
piezos.


I hope the information provided will be helpful. If you have any further
questions about RMC products, please don't hesitate to contact me.


Best regards,

RMC   Richard McClish"
info@rmcmusic.com
==============================
News from RMC regarding the GR-55 Piezo Subharmonic filter input board ( "RMC OPT-01 Subsonic Filter for GR-55"):

Installing this board allows piezo hex pickup GR-55 users to use the GR-300 COSM Guitar model and improves the stability and tracking  when driving internal PCM Synths  and Guitar to MIDI.   


Richard McClish wrote>

"The development of the preferred solution to the GR-55 tracking problem has been ongoing, and the G5SF retro-fit jackboard was superseded by the OPT-01 module which connects in-line between the GR-55 jackboard and GR-55 main board - see attached pictures.

The OPT-01 is in stock and we've already started shipping them.
Please address all inquiries to my attention  info@rmcmusic.com

I don't have the illustrated instructions completed yet, but installation is very simple :
The metal enclosure is opened by removing 8 identical screws retaining the bottom part. You can disconnect the USB port cable from the main board for convenience after the bottom of the enclosure has been opened.

1) disconnect the GR-55 jackboard from the main board - you can use a small blade to pry the mated connectors apart if needed,
2) make sure the black wire harness is fully engaged onto the second header of the OPT-01 as shown in the pictures,
3) connect the jackboard to the first header of the OPT-01,
4) connect the black wire harness to the main board header,
5) remove the liner from the OPT-01's self-adhesive Velcro patch and fix the module to the steel chassis.
It should look like the picture when installed.  Voila !...

All the connectors are polarized so they can't be connected backwards.

Reassembly is the reverse of dis-assembly.

I hope the information provided will be helpful to all who seek relief from the subsonic over-sensitivity problem. I hope you'll feel it was worth the wait.

Best regards,

RMC   Richard McClish"








Its important to note the installation of this user installable filter board requires no modifications to the chassis, and is reversible, and can be removed from the GR-55 if desired.



stueym

#1
This would actually work out cheaper than modd'ing both my VG and GR.  Sit this device in front of my US-20. before it splits out.  Actually If Richard would do a mod to the US-20 input that would be even more neat for those of us that do the split!!!!

Just a shame that Roland didnt just face up to a well known and documented issue with the piezo devices and fix the (opportunity) in the GR-55.

imall41

#2
Quote from: imall41 on February 21, 2011, 05:24:58 AM
Richard McClish (RMC) is now developing a subsonic filter to help remedy the  piezo noise issues,
we are experiencing with the GR-55.

                Richard McClish Wrote,

"I'm presently developing an in-line 13-pin subsonic filter,
since the GR-55 seems to have the same tracking issue with
piezos.

Of course, the in-line version will be more expensive than the
retro-fit jackboard, but we're trying to keep it under $200.

I'll save your inquiry in a special V(SF folder and I'll contact
you as soon as I have units in stock.

I hope the information provided will be helpful. If you have any further
questions about RMC products, please don't hesitate to contact me.


Best regards,

RMC   Richard McClish"

info@rmcmusic.com

I sent pictures of the 13 pin jack board, along with a number of other photos, of the inside of my GR-55, to Richard at RMC.
(as/per his request)

He is still waiting for a unit from Roland, and his local stores don't have any.

To me, it looks like he will be able to build an internal unit that will be fairly easy to install, (and cost less than an in-line unit).

I installed his Subsonic Filter in my VG-99, and this looks easier.

The VG-99 installation was easy also, this just looks more open, and no "springy thing" to be careful of.

Richard seems as eager as we are to get us a fix for our piezo problems with the GR-55.

I will add updates to this thread as things progress.

brooster

#3
Does the Graphtech system have the same problem?
One more question on Graphtech. If you have both the Acoustic-phonic & Hexpander MIDI preamp does that mean that the 13 pin iscan send the signal for the normal pickup in the GR-55?

imall41

#4
Quote from: brooster on February 22, 2011, 05:15:48 AM
Does the Graphtech system have the same problem?
One more question on Graphtech. If you have both the Acoustic-phonic & Hexpander MIDI preamp does that mean that the 13 pin iscan send the signal for the normal pickup in the GR-55?

Hi brooster,

Yes, the Ghost (Graphtech) saddles have the same noise issues as the RMC saddles.

Yes, your normal pickup signal is sent to the GR-55 through the 13pin cable, with the Acoustic-Phonic/Hexpander System.

Elantric

#5
Internal location for the new RMC GR-55 Subsonic filter (OPT-01) = it will replace the 13 pin input PC board with a new version with integrated active hi-pass (rumble) filter.






imall41

#6
               Update:

The first fix from RMC is going to be an internal jack board similar to the V9SF-001 (used in the VG-99).

It will be the "OPT-01".

Richard is working on the pcb layout now.

I don't know if there will still be an "inline version", which was originally considered.

Now that he has actual measurements, he knows there is ample room inside the GR-55 for the jack board.

This will keep the cost to everyone lower than an inline fix.

No word yet, on when these will ship, but he seems to be moving quickly.

Richard McClish, definitely puts the needs of his customers first.
                       (a quote from a recent email)

"FYI, there's at least 200,000 RMC-equipped 13-pin compatible guitars 
out there and I'm not going to let my customers down, that's for sure.

Best regards,

RMC  Richard McClish"

info@rmcmusic.com


Elantric

#7
<Richard McClish wrote>

The first thing that needs to be determined is the efficacy of subsonic
filtering for tracking improvement in the GR-55. This can be performed by users
having a V9SF-equipped VG-99 and a GR-55 by merely connecting the V9SF
jackboard to the GR-55 and performing play tests.

FYI, the V9SF-001 along with the wire harness from the VG-99 can be disconnected from the VG-99
and connected to the GR-55 main board.
Observe  Red wire #14 is Ground in the GR-55 harness.
Black wire #14 is ground in the VG-99 harness.
On the V9SF-001,  pin 14 is closest to the proximate corner of the board.

The result of those tests will steer the design in the right direction and
I can proceed to create short-term and long-term solutions for this situation.

Since users are likely to have different guitar setups and playing techniques,
and they are spread over multiple time zones, we can have comprehensive data
in very little time.

Please find attached the V9SF installation pictorial for your reference.

With timely help from the community, I'm hoping to get power-user feedback,
so we can proceed with restoring market confidence and preparing exhibitors
for the Frankfurt Messe in Germany in April.

Very best regards,

RMC  Richard McClish


info@rmcmusic.com

Connector removal latches are in black circles

mariogag

#8
Quote from: imall41 on February 22, 2011, 06:26:10 AM
Hi brooster,

Yes, the Ghost (Graphtech) saddles have the same noise issues as the RMC saddles.

Yes, your normal pickup signal is sent to the GR-55 through the 13pin cable, with the Acoustic-Phonic/Hexpander System.

The first thing I noticed 3 years ago when I got my VG8ex is that the piezo are sensitive to "body contact".
It is easily noticeable with high gain patches where everything can go craze by simply grabbing the trem bar.

Is this the same thing as what we are experiencing with the GR-300 or is it something totally different?

Mario

Elantric

#9
QuoteThe first thing I noticed 3 years ago when I got my VG8ex is that the piezo are sensitive to "body contact".
It is easily noticeable with high gain patches where everything can go craze by simply grabbing the trem bar.

Is this the same thing as what we are experiencing with the GR-300


Correct!


<Richard McClish wrote>
Yes, in 2009, I re-designed the Poly-Drive IV preamps for Godin MultiAcs with 12 dB/octave high-pass filtering in the string buffers, and this is helping quite a bit. The current string buffers in those preamps have about 15dB more cut @ 20Hz and 27dB more cut @ 5Hz than the previous revisions.

Using the V9SF subsonic filter adds another 20 dB or so of attenuation at 20 Hz and over 50dB of attenuation around 5Hz which is where most tremolos warble.

We're upgrading all our preamps to reflect the new string buffer design, however, the economy hasn't been helping, and it takes more time to pass the existing inventories as a result.

Of course, this doesn't mean the end of the retro-fit filters since there's about 20 years worth of of piezo-equipped instruments out there.

I hope the information provided will be helpful. If you have any further questions about RMC products, please don't hesitate to contact me.


Best regards,

RMC   Richard McClish
   
info@rmcmusic.com


mariogag

#10
Quote from: Elantric on February 22, 2011, 09:29:49 PM

Correct!


<Richard McClish wrote>
Yes, in 2009, I re-designed the Poly-Drive IV preamps for Godin MultiAcs with 12 dB/octave high-pass filtering in the string buffers, and this is helping quite a bit. The current string buffers in those preamps have about 15dB more cut @ 20Hz and 27dB more cut @ 5Hz than the previous revisions.

Using the V9SF subsonic filter adds another 20 dB or so of attenuation at 20 Hz and over 50dB of attenuation around 5Hz which is where most tremolos warble.

We're upgrading all our preamps to reflect the new string buffer design, however, the economy hasn't been helping, and it takes more time to pass the existing inventories as a result.

Of course, this doesn't mean the end of the retro-fit filters since there's about 20 years worth of of piezo-equipped instruments out there.

I hope the information provided will be helpful. If you have any further questions about RMC products, please don't hesitate to contact me.


Best regards,

RMC   Richard McClish
   
info@rmcmusic.com


Merci,

I'll get one for sure when it will be available.


I just loved this forum......:)

M

Elantric

#11
I have sent my GR-55 to RMC to assist in the final design of the new RMC Subsonic Filter for GR-55

Nokie

#12
Quote from: imall41 on February 21, 2011, 05:24:58 AM
Richard McClish (RMC) is now developing a subsonic filter to help remedy the  piezo noise issues,
we are experiencing with the GR-55.

                Richard McClish Wrote,

"I'm presently developing an in-line 13-pin subsonic filter,
since the GR-55 seems to have the same tracking issue with
piezos.

Of course, the in-line version will be more expensive than the
retro-fit jackboard, but we're trying to keep it under $200.

I'll save your inquiry in a special V(SF folder and I'll contact
you as soon as I have units in stock.

I hope the information provided will be helpful. If you have any further
questions about RMC products, please don't hesitate to contact me.


Best regards,

RMC   Richard McClish"
info@rmcmusic.com
I will be interested in how well the filter deals with the problem. I've experienced the noise issues with my Carvin NS1 (Graphtech Ghost Piezo system) plugged into the GR-55. The first clue of a problem was found when using the GK-55's tuner. The 2nd string would register as several other strings. That didn't happen with the GK-3 pickup mounted on my Tele. For now I have dropped the GR-55's global sensitivity setting, corresponding to the Graphtech Piezos, to 10 (I have it at 65 for the GK-3 pickup). In addition, certain settings such as saxophone require individual sensitivity settings. With those adjustments, the extraneous noise problems are gone but the individual patch sensitivity settings have to re-adjusted when I go back to the GK-3. It's great to hear a potential solution to the problem is already being developed. -Marty

Dukemaster

#13
Any ETA and price for this?

imall41

#14
Quote from: Dukemaster on February 24, 2011, 07:20:44 PM
Any ETA and price for this?

I'm guessing the price will be somewhere around $160-$180.(just a rough guess)

I just looked in my checkbook, and I paid $145 for the V9SF-001(VG-99 filter).

But the OPT-01(GR-55 filter), may be a little more involved than the V9SF version.

Richard should get Elantric's GR-55 tomorrow, and hopefully we may have some news on price and ship date by next week.

I don't think it's going to take too long. Richard is very eager to get this to us.

If you are definitely going to get one of these, you could contact him here to get on the order list.
info@rmcmusic.com

Elantric

#15
QuoteRichard should get Elantric's GR-55 tomorrow,

Actually Richard got my GR-55 today.

Those prices may be right for the internal version of the new GR-55 filter board., but if  / when an external Inline filter hits the streets - i expect it to be a bit more.  Richard has stated he had hoped to keep in under $200. Those metal chassis do Add a lot to the final cost, and these are essentially build to order - and the numbers are very very small.

EDIT: Get and external Inline GK  Input Subsonic Filter here:

DR Joness  Filter/Buffer - Guitar Synthesizer Processor with Subsonic Filters, Auxiliary Inputs and Master Effects Loop
http://www.joness.com/gr300/Filter-Buffer.htm
https://www.vguitarforums.com/smf/index.php?topic=9692.0

CodeSmart GKFX-11 Subsonic Filter
https://www.vguitarforums.com/smf/index.php?topic=11884.0

jkstraw

#16
If an inline becomes available can it be used in conjunction with a US-20 to resolve the issue for both the VG-99 and GR-55 at the same time?

stueym

#17
Thats would be my hope too.  Put it just after the cable from guitar to the US-20 input and voila you'd have a cleaned up signal to both devices.  Fingers crossed thats what occurs.  The other thought I put out there was whether Richard could create a board that would actuall go into the US-20 but potentially the market is too small or the real-estate in the US-20 too limited.  Oh well dreamers can dream  ;D

imall41

#18
Quote from: jkstraw on February 25, 2011, 05:23:33 AM
If an inline becomes available can it be used in conjunction with a US-20 to resolve the issue for both the VG-99 and GR-55 at the same time?

                   Richard McClish (RMC) wrote on 2/23/11

"Of course, the in-line solution addresses the VG-8, VG-88, VGA 
amplifier and the US-20 as well as the more recent units, so it will 
be appreciated in the market. Bypassing installation issues is a plus 
in many people's eyes, I agree.

However, when you consider two replacement jackbaords, they are still 
a few bucks cheaper than the in-line unit plus an additional Roland 
cable.

Cable clutter can be kept to a minimum by purchasing the short (2m) 
13-pin cable. I use them for preamp testing in production.

I'll get to designing the inline unit after I create the G5SF for immediate release.

Best regards,

RMC"

info@rmcmusic.com

carlb

#19
Just in from the Onion News Network:

"Roland virtual-guitar designers, near masters of the digital realm, are befuddled by the design of an analog high-pass-filter. The issue arose again with the GR-55 exhibiting the exact problems as the VG-99 used with piezo hex pickups on some patches.

"'We wanted to put a filter in. We've tried tried and tried, but all the equations and stuff are just too much for us,' an embarrassed Roland engineer who asked not to be named said. "Shees, that stuff is just ridiculously hard. No one takes analog stuff in school anymore, that's just a waste of time."

"Asked why they could not just reverse engineer the RMC subsonic filter, he related, 'but that has those little surface mount ICs on it! Itty-bitty traces, resistors and caps no bigger than a toasted black sesame seed. Its just not possible. We've tried! Even with a magnifying glass.'

"Asked why they could not invite some of their fine analog engineers (who designed great analog filters for the likes of the JC120) to help out, the senior principal designer explained, 'Well, we sacked all those guys years ago. Ehm, they don't want to talk with us, and just laugh at us now. They're being really mean.'

"Roland executives are refusing all offers to help, exclaiming defiantly, 'Perfect product as-is! Analog stupid!'

"Roland marketers explain, 'that buzzy loud-assed really annoying sound problem just doesn't exist.
That's all from the guys at Line-6 who are just jealous of us.'

ES Les Paul, internal Roland GK
Boss SY-1000, Valeton Coral Amp pedal
Morningstar MC8 & MC6
QSC CP8 powered speaker

carlb

#20
We can always hope a bit of chiding gets them off their collective butt. And if not, we're perfectly justified in pondering why they can't put a simple high-pass-filter at the input of their device.

And now for the serious side of why analog pre-filtering is the correct solution, versus digital post-input filtering.

Without analog pre-filtering for piezo near-DC crud, the input amplifiers for the VG or GR can rail. A lot of gain is needed to present the signal correctly to input Analog to Digital Converters (ADCs). Without pre-filtering, the majority of energy and amplitude is in that below-hearing frequency range.

As such, that stuff will rail the input amplifiers. And no amount of post input stage filtering will get rid of it: once coupled to the plus and minus supply rails, that noise travels throughout anything powered by those particular supplies (unless heavily de-coupled, which is not standard design practice).

So, you can turn the string inputs all to '0' from the VG or GR display, and you'll still hear this crud. Rest your palm on the bridge, or even get near it, and "BUHWAAAAAHZZZZZZ."

I'm looking into the possibility of a simple in-guitar fix. Not as effective as the RMC unit, but goes to the source to attempt a problem fix:the piezo elements themselves.
ES Les Paul, internal Roland GK
Boss SY-1000, Valeton Coral Amp pedal
Morningstar MC8 & MC6
QSC CP8 powered speaker

MCK

Here's what Roland Marketing people probably say to Roland Engineering guys...

Make it sound bad with the piezo based guitars our competition is selling so that more guitar makers buy and install our OEM GK-3 kits... Competition is annoying... Lets crush them by making sure we don't support their products...

In other words why would they care about this problem if it doesn't occur at all on their platform? I am not surprised at all.

carlb

#22
You are 100% correct. I was being facetious. Roland/Boss just do not care enough to do anything about it.

Perhaps I'm laying too much at their doorstep.

Perhaps it's the Piezo system designers that really need to do something about this.

I did correspond a bit with an engineer for the Ghost system:

"Hi Carl,

I believe the problem you are experiencing is addressed by the RMC PIEZO SUBSONIC FILTER for use with VG-99.

As for adding caps to the piezos, this isn't likely to be the solution because a) there are already caps in line with the piezo inputs to the Hexpander, b) the Hexpander has high common-mode rejection ratio, so is actively filtering incoming noise like 60Hz hum, and c) the piezos are mostly capacitive elements.

A simple test: unplug the ghost pickups from the Hexpander. Do you still get the noise on the GR-300 emulation? Yes? Then it's not coming from the pickups. No? Check if your strings are properly grounded. They may be acting like antennae and drawing additional noise into the system. (what saddles are you using? Some are prone to ground lifting, and I can advise to solve this).

As for adding the filtering to the guitar, I think you'd want to add it to the output side of the Hexpander, not the input side. Essentially it would be the same as the RMC filter, but at the guitar end of the 13-pin cable, instead of at the input to the converter.

See what you can find out about the RMC filter, and if it's something you can imagine adding to your guitars."

My reply:

"Hi Morgan,

The noise occurs when your palm either touches, or gets too near the bridge, suggesting an imbalancing effect (the palm) at the top of piezos to their bottoms. The strings themselves are grounded to common ground.

This noise is very subtle on the modeling patches, hardly noticeable except on the high gain amp settings.

But when using the "GR-300" synth model, the bridge-proximity noise becomes very loud. Roland essentially ups the gain and clips the string inputs to square waves at the start of that model. So, both the power line noise, and low-frequency mechanically induced variations cause these models to become unusable.

The RMC module solves this for the VG-99. The input of the GR-55 can't accommodate that board.

If you could provide me with the effective (i.e., with feedback accounted for) input impedance into the "+" and "-" diff amp piezo inputs, I can calculate a small  cap value to either replace the input caps, or place in series with them. The idea is to have a roll-off that's not too bad at 80 Hz, but gives you a bit of rejection at 60 Hz - not as good as the RMC module, but able to implement within the guitar.

Thanks for helping - this is problem on all the Carvin synth access guitars (which use this system).

Best regards,

Carl"

No response. I guess they just don't think it big enough problem to deal with. Or they erroneously think it is not a real problem, due to their diff-amp input design for each piezo.

But, differential amplifiers become huge noise amplifiers when an imbalanced (with respect to plus to minus) noise is introduced. Such as that when the palm comes in proximity to, or especially if it touches, the bridge or top of the piezo bridge piece elements.

My thought is to reduce the value of the input caps. They have to be too big as designed - anything but DC is essentially passed without any meaningful low-frequency attenuation.

My guess is they're forgetting about the closed-loop negative feedback (NFB) effect on the input impedance of the IC they're using. NFB dramatically raises the effective input impedance of the input stage. If so what they think is a decent cap value for a decent roll-off to noise reduction compromise would instead be allowing much more "crud" through than they suspect.

My guess - they have .01uF caps in there. I'd have to calculate it, but what is wanted is probably much closer to 100pF or so, if they do have NFB (almost certainly) on the their input diff-amps.

One could make such a  change by replacing the caps on the board, or by putting the smaller caps in-series. You'd need two per string: one for each piezo element lead.

This would not be as effective as the RMC unit. It would however be something that could readily be done within the guitar. There just might be a cap value that's a decent compromise for crud-rejection versus low-frequency guitar response.
ES Les Paul, internal Roland GK
Boss SY-1000, Valeton Coral Amp pedal
Morningstar MC8 & MC6
QSC CP8 powered speaker

surfnorthwest

#23
I use a Godin LGX-SA guitar with the GR55 so woukd this new filter be something I would want to install? What is the improvment I should expect? Thanks

Elantric

#24
Its open to your own subjective opinion.

I sent Richard McClish my GR-55 last week and he initially thought nothing was required, he got excellent Guitar to PCM tracking results using no input subharmonic filter. It was only after i told him the focus of the "problem" is the GR-55 preset patch

"01-3  GR-300 Ctl:+1Oct "  - which uses the COSM Model of a 1981 Roland GR-300 Guitar synth ( Robert Fripp, Pat Methany tone) 

and this is when the Piezo bridge pickup exhibited low frequency rumbles and a lot of low frequency handling noises manifest at the GR-55 audio output. The optional RMC Input Filter board will tame these "Piezo hex PU feeding  the  GR-55" noises  on the GR-300 patch.

It also depends on the year of your guitar too.

In 2009 RMC redesigned the PolyDrive preamp used in Godin's and incorporated a new sub harmonic filter into the new PCBs, but these are only just now shipping in specific model Godin instruments.