Problem with noise gate and Archon loop

[Berg Katse]

Hi, new poster but not infrequent lurker. I recently got a hold of an Archon 50W combo, which I friggin' love.

From what I've seen elsewhere on this forum, the Archon 100W head has a series effects loop, so I assumed that to be the case with my 50W combo. Unfortunately, I just took delivery of an ISP Deci-Mate G (basically mini version of Decimator G String pedal) yesterday and cannot get it to work in the loop of my Archon. Confirmed and re-confirmed the proper signal paths per ISP's docs, but as soon as I activate the loop, all sound cuts off with the Deci-Mate G in place.

After poring over their FAQ, I saw that the pedal won't work in a parallel effects loop. So I tried checking my loop with jacks hanging from send and receive but no pedals connected in between. And I was surprised to hear a good amount of thinned out signal (guessing preamp only) coming from the speaker when I switched the loop on.

So can anyone tell me if the 50W combo actually does have a parallel loop, or is it time for me to start looking for problems in my loop circuit?

 

[elvis]

It’s a series loop.

Even in a series loop there are parasitic paths around the loop, so you’ll never get zero sound if the loop fix are off, but it should only bleed very little.

What is the exact problem you’re having?

 

[elvis]

And how do you have the pedal wired?

 

[Berg Katse]

Hey, thanks for the reply. It's actually quite a lot of signal I seem to be getting, as if there were only a ~20dB cut to the sound otherwise. Not sure if that's normal for the Archon or not.

Pedal wiring is per the provided the Deci-Mate manual:
Guitar > DEC guitar input
Archon send > DEC IN
DEC OUT > delay pedal input
Delay pedal output > Archon return
DEC guitar output > Archon input jack

I'd add a pic of the ISP manual but looks like I'll need a couple more posts before I'm allowed. When I set it up like this, engaging the loop kills just about all sound, whether the delay pedal is on or off. If I really crank the master, then I can faintly hear the processed signal (with delay when delay=on), but only at unhealthy master level. And I only tried this for a moment because obviously something is very wrong there.

I'm certain that the Decimate pedal is operating correctly because it functions with straight passthrough with a TS pedal (Guitar > TS > Decimate > Archon guitar input). And it also works fine if I set up the TS pedal in the Decimate's loop (Guitar > DEC guitar in /// DEC guitar output > TS input /// TS output > DEC IN /// DEC OUT > Archon input jack).

 

[elvis]

Tricky. I recommend
Guitar -> DEC guitar in
DEC guitar out-> Archon in
Archon FX SND -> DEC IN
DEC OUT -> Archon FX RTN

Make sure to use TS cables, not TRS,with the Archon loop connections.

Make sure it works with no pedals first. Sometimes pedal or cable interactions can cause a problem.

I used a decimator G and later a TC Sentry with an Archon no problem.

As for the loop bleed, it will be a lot louder with just a cable connected than if a pedal output is connected to FX RTN. It’s an impedance issue.

 

[elvis]

Might try swapping the DEC in and out cables in the Archon FX loop if that didn’t do it. Could be a cabling error.

 

[Berg Katse]

I tested again using the cabling you recommended (no delay in the loop this time, just the deci-mate G), all [EDIT: TS] patch cables. The best I'm getting is maybe a tiny bit of hiss reduction with the loop on and no benefit whatsoever with the loop off.

By the way, isn't the G version of the pedal supposed to reduce both loop noise AND guitar input noise at the same time? I find that with the current cabling, even if there is a tiny bit of hiss reduction in the loop, there is absolutely no effect on the guitar input. This can't be right. I'll have to at least screw around with the cabling some more before returning it, though.

I'd been using a Decimator II and more recently a regular Deci-mate just in front of the amp for quite a while now, and it has always been great. I was thinking that the G might provide this same benefit while also helping to reduce loop hiss.

 

[elvis]

Not sure if there was a typo in your post, but all the cables should be TS, not TRS.

I believe the g version uses the guitar signal at the front to gate the loop. I don’t think it reduces noise in the front, though I may be mistaken.

I’m not sure what is going on, the gate in the loop should stop all the noise UNLESS you have a noisy tube in the power amp, which is possible.

 

[Berg Katse]

Ah, that was a typo. Fixed, but yes, they are all ordinary TS patch cables.
I have plenty of tubes, so I could try rolling the power amp and maybe preamp V6/loop just in case.

Maybe I misunderstood the purpose of the G version of the pedal. My expectation was that it would still behave like the regular version in front of the amp but provide additional coverage in the loop (with loop on). But if it's actually all or nothing depending on whether the loop is on or off, then I might just stick with the regular Deci-mate out front.

 

[elvis]

It may well give reduction in the front end as well, I just thought it didn’t. Did it help without the loop?

 

[elvis]

Read the advertising copy. Really looks like it only does noise reduction in the loop. You can still put your gain pedals in the DEC loop, even if you are not using the Archon loop all the time. The Archon itself is quiet enough that it don’t need a gate as long as you don’t run the gain full up. Which is really more than you should do anyway, since it just compresses past one o’clock or so.

 

[Berg Katse]

Yep, also confirmed on loop only when used w/ 4-cable method. I found some info on the circuit, and this would apply to the G versions of ISP's gate pedals as well as other side-chain designs. The latest version of the Deci-mate G can function like a non-G version in front of the amp, and without having to bridge the DEC IN/OUT (it's internally bridged if no 3.5mm cable is inserted). But with the four-cable wiring, it only operates in the loop.

I prefer to have a Decimator in front of the amp for when I'm not using a loop since they're so great at killing 60Hz hum and some slight noise from guitars that aren't perfectly shielded. When I'm recording the Archon, it's always through a load box + DI, and I don't even bother with the loop. But at bedroom levels for practicing, I was thinking to add a delay and chorus in just for fun. I think what I'll do is either get a second Decimator II and link it with the one I already had or just forget it all and do what I can to further suppress loop hiss at low volume. This is a post-loop mod amp but I could still probably do better for the tube in V6. I also read that swapping the speaker is useful. (UPDATE: Hah, I just now noticed that PRS has launched a mkII 50W combo, and the newer model features a Celestion V-Type instead of the G12-75T.)