GT-1000core- Noisy Send/Return Loops

Started by houserockr, December 23, 2020, 05:12:21 AM

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houserockr

Hi folks,

I'm using the GT-1000CORE for amp/cab-simulation and modulation effects only, such as reverb, delay and flanger.
OD-wise I've not yet arrived in the digital world and I want to keep my hand full of good old analog OD pedals.
Klone, TS808, Bluesbreaker, Univibe, Fuzz. I tested their digital sim in the GT1k and they're good, but I guess it's psychological that I prefer the "originals".

However, my actual problem with the GT1kCore is that the two send/return loops are really noisy and I don't know if it's normal.
Originally, I wanted to put the Fuzz (Analogman Sunface) completely before the GT1k, all the ODs in Loop 1 and my Boss CE-2w in Loop 2.

However the loops introduce a lot of noise!

I can eliminate that it's hum from a ground loop, because I've tried all the different ground-lift options in the main menu, no difference.
Also, the noise is definitely more hiss than hum, higher in frequency.
I can eliminate that it's coming from the pedals or the cables, because as soon as I put ALL pedals before the GT1k, there's no noise whatsoever.
I'm using Evidence Audio SIS cables, but I also tried cables from a different manufacturer (Rockboard flat).
I also tried patching send to return directly using many different cables, ... NOISE!

Both Loop-Blocks are in "normal" mode (i.e. full send and return of the signal) with send- and return-level of 100 and adjust (phase) of 0.
I also tried positioning the Loop-Blocks in different locations of the fx-chain, no difference.

The main out of the GT1k is "recording" and the stereo out goes directly into my mixer.

Any hint appreciated.

Frank

Tonemasterus

Mine are dead quiet.  There is some ground loop settings in the menu.  I'm using batteries though rechargeable 9v.

David

PAH

Try switching a S/R loop on and off with nothing plugged into the send or return jack.  The GT will internally connect send and return in this case in the analog domain, so it is logically equivalent to a patch cable between send and return, but eliminates the cable.  If enabling a normal mode Send (100) /Return (100) loop with nothing connected to send or return introduces a lot a noise, I'd say you've got a bad unit. 

houserockr

Quote from: Tonemasterus on December 23, 2020, 06:58:51 AM
Mine are dead quiet.  There is some ground loop settings in the menu.  I'm using batteries though rechargeable 9v.

David
Yep, thanks, like I wrote, I tried all the different ground-lift modes, no difference, tho :(

houserockr

Quote from: PAH on December 23, 2020, 10:50:27 AM
Try switching a S/R loop on and off with nothing plugged into the send or return jack.  The GT will internally connect send and return in this case in the analog domain, so it is logically equivalent to a patch cable between send and return, but eliminates the cable.  If enabling a normal mode Send (100) /Return (100) loop with nothing connected to send or return introduces a lot a noise, I'd say you've got a bad unit.
So I just tested an s/r loop without anything connected to it and when I turn it on in the fx-chain, it introduces noise. The same noise I've been observing all the time, even with pedals and cables connected to it.
I'll make a video and upload it to youtube, so you guys can get an idea of the level of noise. It's not much in a crunch sound, but in high gain settings, it becomes unbearable.

houserockr

Here's a short video I just made.


Notes:
- all the analog pedals are in front of the GT1kCore
- nothing connected to S/R-1
- mode of both s/r blocks is "normal" with levels of 100 and phase/adjust of 0
- cables used are evidence audio SIS
- guitar connected is a Fender custom shop strat
- guitar cable is a Fender 10ft
- Boss CE-2w chorus (top left) connected to S/R-2
- patch-001 (Jimi) is a crunch sound with a Plexi (model brit stack)
- patch-007 (Tool) is a metal sound with a bogner uberschall and a x-high-gain model.
- stereo line out of the Gt1kCore goes directly into my mixer and from there into my phone, which is also filming

admin

#6
Quote from: houserockr on December 24, 2020, 01:12:53 AM
So I just tested an s/r loop without anything connected to it and when I turn it on in the fx-chain, it introduces noise. The same noise I've been observing all the time, even with pedals and cables connected to it.
I'll make a video and upload it to youtube, so you guys can get an idea of the level of noise. It's not much in a crunch sound, but in high gain settings, it becomes unbearable.

make ONE custom 1/4" TS patch cable for the GT-1000 Core  FX Loop for the FX Loop Return from  external FX - but with its  Ground Shield lifted  (i.e. only a Tip connection - Shield connected only at one end of the TS cable - often tames pedal board ground loop noise on complex modern pedal board   - Ground loop Noise manifests today as white noise "HISSS"  - due to all the internal DSPs and Switch mode power modules internal on our favorite effects
and label any custom "Open ground" cables you make - as they may not work anywhere else but on the pedal board FX loop connection.

houserockr

Quote from: admin on December 24, 2020, 07:20:37 AM
make ONE custom 1/4" TS patch cable for the GT-1000 Core  FX Loop for the FX Loop Return from  external FX - but with its  Ground Shield lifted  (i.e. only a Tip connection - Shield connected only at one end of the TS cable - often tames pedal board ground loop noise on complex modern pedal board   - Ground loop Noise manifests today as white noise "HISSS"  - due to all the internal DSPs and Switch mode power modules internal on our favorite effects
and label any custom "Open ground" cables you make - as they may not work anywhere else but on the pedal board FX loop connection.

Thanks for the tip mate. However, I don't see much sense in doing that, because - like I wrote - the noise is also introduced with nothing connected to a s/r loop whenever the corresponding loop-block is activated in the fx-chain in the unit. Plus, the settings allow you to do exactly what you suggested, lift the ground of the return. I tried that, it didn't have any effect whatsoever.

Meanwhile, I visited a friend of mine who happens to have the big cousin of the CORE, the GT-1000. He has the exact same thing on his unit. He just didn't notice, because he doesn't use the loops.
So I guess I don't have "just a bad unit".

houserockr

Quote from: admin on December 24, 2020, 07:20:37 AM
make ONE custom 1/4" TS patch cable for the GT-1000 Core  FX Loop for the FX Loop Return from  external FX - but with its  Ground Shield lifted

I did it anyway, simply because I'm getting desperate with this issue.
It didn't help, sorry.
Noise, noise, noise.

PAH

My GT-1000 does not introduce any perceptible noise when I turn on a S/R loop with nothing connected.

Whenever I use my piezo bridge, I have a loop enabled, and use the return as an alternate input - no noise.

My bass patch, has a S/R loop enabled at the front end of the chain.  Usually, I don't have anything connected to that loop, but it gives me the option of plugging my bass into that return, so I can switch between guitar and bass without unplugging and plugging the cable from/to the instruments - no noise regarless of whether I have my bass connected to the return, or nothing connected to it.

houserockr

Quote from: PAH on December 28, 2020, 08:40:12 AM
My GT-1000 does not introduce any perceptible noise when I turn on a S/R loop with nothing connected.

Whenever I use my piezo bridge, I have a loop enabled, and use the return as an alternate input - no noise.

My bass patch, has a S/R loop enabled at the front end of the chain.  Usually, I don't have anything connected to that loop, but it gives me the option of plugging my bass into that return, so I can switch between guitar and bass without unplugging and plugging the cable from/to the instruments - no noise regarless of whether I have my bass connected to the return, or nothing connected to it.

Okay, thanks for posting.
That's not good - for me.
I contacted support, so we'll see.
I just hope I don't have to send in the unit and wait for x weeks, because I don't have a replacement at the moment.

gumtown

Try this, since going into a mixer input, there is a possibility that the GT-Core, pedals and guitar are not actually grounded to ground (as in to the general earth mass via mains outlet earth connection).

Try plugging in a grounded guitar amp (plugged into the mains), it can be switched off, and a guitar lead from the grounded amp to any socket on the GT-Core.
or
a copper wire from the GT-Core chassis to a grounded metal item.

also check that your GT-Core does not have a USB cable plugged into a computer too (try with or without USB cable connected).

 
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

houserockr

Quote from: gumtown on December 28, 2020, 02:48:11 PM
Try this, since going into a mixer input, there is a possibility that the GT-Core, pedals and guitar are not actually grounded to ground (as in to the general earth mass via mains outlet earth connection).

Try plugging in a grounded guitar amp (plugged into the mains), it can be switched off, and a guitar lead from the grounded amp to any socket on the GT-Core.
or
a copper wire from the GT-Core chassis to a grounded metal item.

also check that your GT-Core does not have a USB cable plugged into a computer too (try with or without USB cable connected).

Thanks, that was actually a very promising idea! Especially because the chassis of the GT1kCore has a dedicated ground screw.
I connected that screw with a ground wire from an audio RCA cable to my heater (which in Germany are grounded).
Unfortunately, that introduced additional hum. Hum as in 50 cycle hum. Which means by doing that I introduced a ground loop.
No USB was connected.
I don't have an actual amp, so I can't test that atm, unfortunately.

vtgearhead

Quote from: houserockr on December 29, 2020, 03:22:11 AM
Thanks, that was actually a very promising idea! Especially because the chassis of the GT1kCore has a dedicated ground screw.
I connected that screw with a ground wire from an audio RCA cable to my heater (which in Germany are grounded).
Unfortunately, that introduced additional hum. Hum as in 50 cycle hum. Which means by doing that I introduced a ground loop.
No USB was connected.
I don't have an actual amp, so I can't test that atm, unfortunately.

Not sure about German electrical code, but in the US a device can be grounded per standards and still be at a potential large enough to cause noise in high-gain audio systems.  In environments were you need quiet audio (theater, recording studio) it's typical to return all grounds separately to the best actual ground available - usually cold water entrance point.  I'm not surprised it got noisier when tied to the heater. 

szszoke

#14
Try playing around with the ground lift settings under MENU > HARDWARE SETTINGS > GROUND LIFT.

How close do you live to your friend? Could something in the grid cause your issues?


houserockr

Quote from: szszoke on December 30, 2020, 03:17:18 PM
Try playing around with the ground lift settings under MENU > HARDWARE SETTINGS > GROUND LIFT.

How close do you live to your friend? Could something in the grid cause your issues?



Thanks mate, that video made me laugh real hard. I've been following samurai for quite a while.

My friend and I live far enough apart so I can be certain that he's powered from a different grid. There's at least 40km of separation.

I tried all the different ground-lift options in the menu (see above) - no difference whatsoever.

houserockr

Quote from: vtgearhead on December 29, 2020, 01:05:17 PM
Not sure about German electrical code, but in the US a device can be grounded per standards and still be at a potential large enough to cause noise in high-gain audio systems.  In environments were you need quiet audio (theater, recording studio) it's typical to return all grounds separately to the best actual ground available - usually cold water entrance point.  I'm not surprised it got noisier when tied to the heater.
Yep, heaters are a reliable ground source in Germany.
Since my mixer is a DJ mixer with RCA inputs for turntables, I also tried connecting the ground screw of the GT1k to the ground screw of my mixer. No difference.

szszoke

Since my last reply I received my own GT-1000 unit.

I can confirm that my unit also becomes a tad noisier when I enable the FX loop.

I made a recording where the different levels of noise can be heard.

Here is a timeline:

00-03 - background noise of my Focusrite Scarlett 2i2 gain knobs at 100%, GT-1000 output level knob at 0%
03-09 - GT-1000 output level knob at 100%
09-15 - SEND/RETURN with STEREO LINK ON, MODE NORMAL, SEND/RETURN levels at 100, ADJUST at 0
15-19 - NS THRESHOLD set to +20dB in MENU > IN/OUT SETTING > TOTAL
19-22 - GT-1000 output level knob at 0%, Focusrite Scarlett 2i2 background noise can be heard

NS1 was active at the beginning of the effect chain at all times with the following settings:
THRESHOLD - 50
RELEASE - 30
DETECT - INPUT

I had two 1.5m mono cables running from the main output into my audio interface.
Nothing was plugged in to the inputs or into the SEND/RETURN jacks.
Nothing was plugged in to the EXP1 jack.
Nothing was plugged in to the EXP2 jack.

Here are my observations:
1. The overall noise was reduced after I turned up the NS THRESHOLD in MENU > IN/OUT SETTING > TOTAL
2. Enabling the FX loop introduced some (white?) noise that was audible on high output levels
3. The USB output was crystal clear

It is quite late here so I used headphones for my testing.

Tomorrow I will try to use 2 KATANA 100 MKii amps and see how much noise can be heard.

Try turning up the NS THRESHOLD in MENU > IN/OUT SETTING > TOTAL and see if it helps.

Also, to reduce the number of variables, we should use the same patch for testing.

szszoke

I did some testing with 2 KATNA 100 MKII amps. The outputs were connected to the POWER AMP IN jacks.

I also get a very audible noise that only stops if I engage a noise gate after the SEND/RETURN block.

houserockr

Thanks szszoke for joining the discussion and for testing with your Katana.

Simply ignoring it and put a noise gate behind the send/return blocks is not an option for me.
I'm a strat player, I'm used to noise and I dislike noise gates a lot.

"Then why are you complaining about that tiny bit of noise from the send/return?" I hear you ask.
Well, I embrace natural static noise coming from my single coils being amplified or noise coming from my analog pedals and patch cables.
However, I do not embrace unnecessary noise coming from a send/return loop that nothing is connected to.

Also, I'm wildly speculating and guessing that everyone who wrote that their send/return loops are "dead quiet" had a noise gate active somewhere after the send/return blocks in the fx-chain.

No answer from the Boss/Roland support so far.

szszoke

Hey! No worries!

I am thinking that maybe the DACs are causing the noise?

I attached a screenshot where the USB output is visible. I set the USB level to 200% on the unit.

The USB output is practically silence.

PAH

I never use a noise gate, and my GT-1000 S/Rs are dead quiet when nothing is connected.

I am in the US (60Hz power), using the Boss power supply, and running:

Guitar (TRS output) -> splitter to separate mag and piezo pickups
mag pickups -> GT input
piezo -> Return 1
sometimes bass -> return 2, sometimes bass -> splitter -> input (depends on how much I'll be switching between the guitar and bass)
External expression pedal -> exp 2
main out L/mono -> a mixer -> FRFR (or directly to an FRFR at home)


szszoke

I think me and houserockr are both from the EU. Maybe the 50Hz power makes a difference?

I am also using the power supply that came with the unit by the way.

houserockr

I've tried many power supplies:
- The original PS that came with my unit
- The original PS of my friend's GT-1000
- My Truetone 1-Spot CS7 (with a current doubler)
- My Voodoo Labs Pedal Power Plus (with a current doubler)

No difference. But I agree, I could imagine that the frequency of the power grid might be an issue.
But this one will be hard to test/prove, because I don't have any options to try this with a 120V/60Hz power.

houserockr

The Roland support replied.
I'll post the original German text at the end of the message, so German natives can read it.

They're basically saying that the behavior I described is expected and part of the (quote) device's specifications and that there's no problem.
Additionally, they're suggesting to (quote) work with a noise gate to filter unwanted noise.

What a joke!!!

(...)
Hallo Herr xxx,

vielen Dank für Ihre Anfrage sowie die Übersendung des Videos.

Die von Ihnen genannten Beschreibungen sind Spezifikation des Geräts. Es handelt sich um keinen Gerätedefekt.
Eventuell empfiehlt es sich, mit einem Noise Gate zu arbeiten, um eventuell ungewollte Störgeräusche herauszufiltern.

Weiterhin wünschen wir Ihnen viel Spaß mit dem Gerät.

PS: Wenn Sie mit unserem Service zufrieden sind, freuen wir uns über eine Rezension auf Google.
Mit freundlichen Grüßen
Roland Customer Support

(...)