Decimator Gstring Debug / Help!

[mremic01]

I don't know what you guys are doing that you're drive pedals are causing noise. Even with super gainy stuff like DR Boogey, I've only had oscillation when I didn't ground the input and the gain was turned all the way up. Any noise I've ever gotten has been amplified by those pedals, not caused by them. Nip them in the bud, and there's no noise left to amplify. At the end of the chain has done nothing for me regarding feedback too. The feedback gets amplified by whatever I'm using for a boost and gets strong enough to get past the gate. But with the gate first, it never gets loud enough to start a feedback loop.  But yeah, if your rig is noisy, you put it after what's causing the noise.

[Harold]

I don't know what you guys are doing that you're drive pedals are causing noise.

My Kafuzz (Big Muff) is always on, and my WH10 makes all kinds of noise when engaged, especially when the Kafuzz and Distortion 15 amplify that. I even can hear my Ross Phaser phasing when I mute my guitar ... that's why I have a G-String (center) in my rig: works perfectly.




But we're not here to judge each other's hiss, but to fix some G-Strings. Mine has no signal on pin 1 of the THAT chip.

[TheWinterSnow]

I don't know what you guys are doing that you're drive pedals are causing noise. Even with super gainy stuff like DR Boogey, I've only had oscillation when I didn't ground the input and the gain was turned all the way up. Any noise I've ever gotten has been amplified by those pedals, not caused by them. Nip them in the bud, and there's no noise left to amplify. At the end of the chain has done nothing for me regarding feedback too. The feedback gets amplified by whatever I'm using for a boost and gets strong enough to get past the gate. But with the gate first, it never gets loud enough to start a feedback loop.  But yeah, if your rig is noisy, you put it after what's causing the noise.

Quite a bit off base there.  

Specifically a side-chained noise gate is not meant to go after the noisiest pedal, the side-chain signal is your guitar, you want it to turn the gate on and off based on if you are playing something on the guitar or not.  By placing the gate in the FX loop when you are not playing the guitar at all, the FX loop becomes an open and kills all volume, that way you are not depending on all your amp gain and noise getting passed the gate, because the gate reacts to the raw guitar signal, not all the gain you added to it.  You stop playing guitar, or rather, the pickup signal drops below the set threshold, the gate turns off no matter what is on the gate input.  The gate reacts to the side-chain signal and the side-chain signal only.

The biggest reason for a noise gate is to kill uncontrollable feedback when playing at high gain and high volume.  If you play hard rock and metal, band rehearsals and shows are a nightmare without them as even if your amp is at low volume, your pickups interacting with the FOH in small venues/bars will still cause feedback.  If the 4-input style noise gates like the G-String are used correctly, they do eliminate all noise and all uncontrolled feedback (but only when not playing), even those created by pedals.

I will also add, the reason the topic does not show up is because it was deleted.  Some newbie idiot came in the thread about wanting to build one and then asked about patent infringements, then asked owner/mod of this site to delete his posts and around the same time the company in question made note that they were informed of possible patent violations (coincidence?) which wasn't the case because no one was building and selling them for profit or trying to pass it off as their own design, but I digress.  Most recent threads on the topic were blocked, then shortly deleted, and some of us moved over to the members only forum to talk about some of the non-patented technologies and went off to create our own noise gate from scratch based on similar performance figures, the company and product were never mentioned and that thread was thus locked and then about a month later deleted.  I imagine the same will happen to the two new ones that were bumped, screenshot them while you can.

[Harold]

Here's the component numbers according to this schematic: http://img.sait.nl/schematics/isp_g_string.jpg


http://img.sait.nl/schematics/isp_g_string_layout_numbers.png

In my build my signal mutes between R3 and the THAT.

I found this differences between the layout and the schematic:

Component   Schematic   Layout
D3   1N4148   2x1N4148
D4   1N4148   2x1N4148
R9   27K   51K
R10   100K   150K
R12   10M   20M
R13   20K   12K
R14   20K   12K
R30   10K   20K
R32   68K   22K
R37   620R   560R

Missing from the layout: C3 and R32

[Harold]

some of us moved over to the members only forum to talk about some of the non-patented technologies and went off to create our own noise gate from scratch based on similar performance figures

Cool! 

Got a link/name?

[Harold]

And the THAT voltages: (Vin = 9.07v)

1 7.55v
2 8.34v
3 8.24v
4 8.34v
5 5.41v
6 8.25v
7 9.07v
8 7.60v

[Harold]

I seem to have a problem with Vr, whch is 8v atm. I'll check that tomorrow ...

[Govmnt_Lacky]

@Harold

So many questions in the layout that you posted above....

- Where does C2 connect to? One side goes to R1... the other goes off into never land 
- Where is the Trimmer that goes below R36? Should be 1M correct?
- This looks like the G-string version but, I don't see the SEND pad anywhere. Am I missing it?

I built Slade's version of this circuit and it worked fine. This layout looks kinda like it but there appear to be several holes in it 

[mremic01]

Here are my voltages, for Slade's non-G-String layout:

LF353N
4.67
4.67
4.66
0
3.3
3.3
3.2
9.36

Top LF347N
2.64
2.64
2.64
9.35
3.23
3.24
3.82

3.38
3.38
3.37
0
4.65
4.66
4.66

Bottom LF347N
4.65
4.66
4.24
9.36
4.66
4.66
4.67

4.66
4.67
4.67
0
4.33
4.34
3.15

I can't get my probe under the THAT to check its pins, sorry.

[mremic01]

I don't know what you guys are doing that you're drive pedals are causing noise. Even with super gainy stuff like DR Boogey, I've only had oscillation when I didn't ground the input and the gain was turned all the way up. Any noise I've ever gotten has been amplified by those pedals, not caused by them. Nip them in the bud, and there's no noise left to amplify. At the end of the chain has done nothing for me regarding feedback too. The feedback gets amplified by whatever I'm using for a boost and gets strong enough to get past the gate. But with the gate first, it never gets loud enough to start a feedback loop.  But yeah, if your rig is noisy, you put it after what's causing the noise.

Quite a bit off base there.  

Specifically a side-chained noise gate is not meant to go after the noisiest pedal, the side-chain signal is your guitar, you want it to turn the gate on and off based on if you are playing something on the guitar or not.  By placing the gate in the FX loop when you are not playing the guitar at all, the FX loop becomes an open and kills all volume, that way you are not depending on all your amp gain and noise getting passed the gate, because the gate reacts to the raw guitar signal, not all the gain you added to it.  You stop playing guitar, or rather, the pickup signal drops below the set threshold, the gate turns off no matter what is on the gate input.  The gate reacts to the side-chain signal and the side-chain signal only.

The biggest reason for a noise gate is to kill uncontrollable feedback when playing at high gain and high volume.  If you play hard rock and metal, band rehearsals and shows are a nightmare without them as even if your amp is at low volume, your pickups interacting with the FOH in small venues/bars will still cause feedback.  If the 4-input style noise gates like the G-String are used correctly, they do eliminate all noise and all uncontrolled feedback (but only when not playing), even those created by pedals.

Umm, I'm not at all sure what was off base about what I said, and what you said seems to support my reasoning, unless your talking about the G-String. I'm talking about the regular Decimator. With the regular Decimator, putting it directly after the guitar does exactly what you said it should: it eliminates all noise and uncontrolled feedback only when not playing. After ANYTHING that amplifies pre-existing noise, you need to turn up the threshold to get it to gate that noise, and then you have to deal with the fact that the appropriate threshold varies if you've got a boost pedal that you're turning on and off. The boost might push your noise above the gate's threshold. This was a problem I had with my TS. It was even worse with the older version of the MXR Smartgate, the thing was useless anywhere other than first in the signal chain. I'm not the only one who uses it this way, I got the tip from UG years ago.

Have you guys even tried running the regular Decimator first? It's easy to assume a pedal is noisy. All my distortions have noise, but with the gate in front of them, they're dead quite when I'm not playing. That makes it pretty clear that its not the pedals that cause the noise. But with the gate first, feedback can't start. Single coil hum doesn't get through. Nothing. Dead quiet. Does exactly what I want, despite that manual says to put in the loop or after the board.

[Harold]

See inline:

@Harold

So many questions in the layout that you posted above....

- Where does C2 connect to? One side goes to R1... the other goes off into never land  
The orange trace extends to the right: so C2 goes to Vr
- Where is the Trimmer that goes below R36? Should be 1M correct?
The trimmer is not depicted, it's in the lower left corner of the layout: Vin/wiper/GND
- This looks like the G-string version but, I don't see the SEND pad anywhere. Am I missing it?
Yep: like I said, "Missing from the layout: C3 and R32", so I added them before etching the board, see below.

I built Slade's version of this circuit and it worked fine. This layout looks kinda like it but there appear to be several holes in it  

I've added pads for C3 and R32 on the layout I etched: (gray area)


Download the pdf here: http://img.sait.nl/schematics/isp_g_string_layout_corrections.pdf

[Harold]

Here are my voltages, for Slade's non-G-String layout:

Cool, thanks!!! I must first fix my strange Vr, but this might come in handy!

I can't get my probe under the THAT to check its pins, sorry.

No problem, if my issue isn't fixed after fixing Vr I'll try to get a hold of my nonG-string myself to check it.

[Harold]

Fixed! There was a nasty solder bridge in the Vref section ... 

That is, I can hear my test-beep on the output. My jacks are arriving tomorrow, then I can finish my build and test with actual gear. Turning the threshold up mutes the signal, so I guess it works

I'll report back when I've drilled the enclosure and installed the (isolated) jacks!

[DIMstompboxes]

Hello guys,
I'm out for a while....Just saw and read the whole thread... If I could get THAT IC chip, definitely I would build this G-string version.
BTW I'm using downward expander gate(without send/return) with CA3080 chip and very much effective noisegate in the FRONT of the chain not at the back chain just like mremic01 with my analog setup.
I know for sure it cut/affect my delay and reverb somehow....Feature like send/return is ideal and a must for a noisegate no doubt about it. That is why i'm using two built-in noisegate in my multiFX (front/back) before MODULATION setup in every patch.
@ Harold, mate I saved your correction PDF file just in case... tweet/subscribe on this thread also  


 

[Harold]

@ Harold, mate I saved your correction PDF file just in case...

I'll try to paint the updated components into the gray area some day. Some components got moved around to make room ...

[DIMstompboxes]

@ Harold, mate I saved your correction PDF file just in case...

I'll try to paint the updated components into the gray area some day. Some components got moved around to make room ...

Thanks buddy.

[Harold]

It's done!  




I've dialed in a unity volume with the trimpot using my DMM and a test sine wave at 65mV~ and it works brilliantly!

... if only iSP sold it at this form factor instad of the 1.5 pound Boss rip-off enclosure with 3 jacks on one side?!?

[DIMstompboxes]

CHEERS bottoms up 
Harold, if you find some time please share us your update version and no hurry buddy 

Kiiong Hee Huat Tsai

[DIMstompboxes]

Harold buddy where did you bought your THAT2181C, I search smallbear they got THAT2181LB. Can this be a replacement or not?
@mremic01, I read your post some version of C has issue also, where did you got yours so to be safe. Are there's somehow fake?
BTW what are the replacement for LF347N and LF353N so I could buy locally.

Thanks to both of you 

[Harold]

I live in the Netherlands, so I shop at newtone-online.nl. In the deleted thread it was mentioned quite often that the C version is a must...