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    FX Loop question

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    trifonius

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    FX Loop question

    Post by trifonius on Fri Aug 28, 2015 2:08 am

    I am using the GM36 with a loop station (Boss RC-300).
    In order to be able to record the GM effects and to play the loops back without any extra effect added, I use the FX loop.

    So:
    GM Send -> RC-300 Input
    RC-300 Output -> GM Return

    However:when I switch channels, the output of the RC-300 gets enhanced (unwished for!!) with at least the GM Delay!

    This is very unexpected for me.
    Any ideas?

    Thanks!

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    bordonbert

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    Re: FX Loop question

    Post by bordonbert on Fri Aug 28, 2015 5:17 am

    I have no idea how long you have been a GM user Trifonius but is it as simple as this?  Is any effect, you mention delay, already set to be active with the alternative channel?

    Remember that each channel retains its own last used setup for effects.  If you set up the Clean channel to have Delay and the Crunch to not, every time you select Clean the delay will turn on and every time you select Crunch it will turn off.  When you set it to off in Crunch that will not have turned it off in Clean.  If you want to have no delay at all you must make sure that it is set to 'Off' on each channel.  The Channel selection effectively selects a whole voice, it does not just change the channel while retaining all other settings.

    normula1

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    Re: FX Loop question

    Post by normula1 on Fri Aug 28, 2015 6:02 am

    I had exactly the same issue as the built in FX are post loop.

    This was one of the factors that eventually lead my to selling mine on as to use it for noodling along to myself with any effects meant I had to use an external effects unit as well which kind of defeated the purpose of the GM.

    trifonius

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    Re: FX Loop question

    Post by trifonius on Fri Aug 28, 2015 8:35 am

    O my, this is what I was afraid of. How can the FX be post loop?
    I'm not experienced in this matter, but I thought the whole purpose of the FX loop was to bypass the shaping that takes place in the pre-amp, meaning the effects also?

    How do you know where the fx are in the GM? Is there a schema or drawing available?
    Thanks!!

    Btw, did you sell your loopstation or your GM?

    normula1

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    Re: FX Loop question

    Post by normula1 on Fri Aug 28, 2015 9:58 am

    The GM.

    I'd bought it with a view that it had all the flexibility of a modeller but with the tone of hot bottles, and the built in attenuator would mean I could have a relatively quiet, compact solution for noodling along to myself using a TC Ditto in the loop and not have a gazilion cables to plug / unplug if I wanted to take it elsewhere. And if I wanted it to, I could easily integrated it into my existing MIDI setup.

    In the end though, 1 watt is still quite loud when you turn up the master, I much preferred the tone when in 36 watt mode into an external attenuator. To noodle using Ditto with effects properly I had to retain my TC GMajor in the loop and all the cables that goes with that and when I put it up against my old amps ('73 JMP Marshall, Boogie Studio 22+, self built tube preamp for cleans and a Laney LionHeart 5 watt combo) in an A/B test I much preferred the tone of my old amps.
    And whilst Fredo's excellent PC editor (and the Android editor too) made editing patches a really simple thing to do, the issue with the MIDI Volume pedal was a pain even though I did come up with a work around by setting max volume limits on each patch in my MIDI foot pedal or again controlling volume using my GMajor in the loop.

    Essentially, the GM wasn't working for me in the manner I had thought it would. So after doing lots of tube and speaker rolling and pretending to myself for the last six months that I hadn't made a mistake buying it, I sold it on pretty much to the year after bringing it home and just sucked up the financial loss to experience.

    I'm in no way knocking the amp itself, I'm sure it's perfect for lots of people, just not for me.

    trifonius

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    Re: FX Loop question

    Post by trifonius on Sat Aug 29, 2015 3:00 am

    Any answers on this?
    I keep thinking i'm missing something simple here:

    How can the built in FX be post loop?
    I'm not experienced in this matter, but I thought the whole purpose of the FX loop was to bypass the shaping that takes place in the pre-amp, meaning the effects also?

    How do you know where the fx are in the GM? Is there a schema or drawing available?
    Thanks!!
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    VoodooJeff

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    Re: FX Loop question

    Post by VoodooJeff on Sun Aug 30, 2015 9:47 am

    trifonius wrote:Any answers on this?
    I keep thinking i'm missing something simple here:

    How can the built in FX be post loop?

    It`s just the way it is. Is it ideal? No.

    I'm not experienced in this matter, but I thought the whole purpose of the FX loop was to bypass the shaping that takes place in the pre-amp, meaning the effects also?

    Nope. The loop is just an insert point between the preamp and power amp. *Some* amps do have a direct input to the power amp that bypasses the entire preamp all together, like a reverse direct out. You`d also lose volume control except at the master (not really a big deal)

    How do you know where the fx are in the GM? Is there a schema or drawing available?
    Thanks!!

    No real reason to need a schematic. Set up a looper and start a loop with the built in delay off. Turn the delay on. Does it affect the loop? Then the only possible answer is that the built in effects are post loop. It simply cannot be anything else, and it`s not switchable. I would prefer it to be pre-loop, but it`s not. It`s a great amp but it does have it`s shortcomings.
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    gravydb

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    Re: FX Loop question

    Post by gravydb on Sun Aug 30, 2015 11:24 am

    Different strokes for different folks... personally I'm glad the loop is pre fx, because I have a volume pedal in the loop. The delay and reverb tails aren't cut off when I heel down the VP. So, the GM's configuration is perfect for me.

    I agree your only solution with the GM would be to use external fx which kinda defeats the GM's concept but I don't know what else you can do.
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    bordonbert

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    Re: FX Loop question

    Post by bordonbert on Sun Aug 30, 2015 4:05 pm

    Now if H&K would only put in a PAIR of FX loops, one pre and one post, everybody would be happy..... Laughing
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    VoodooJeff

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    Re: FX Loop question

    Post by VoodooJeff on Thu Sep 10, 2015 11:09 am

    bordonbert wrote:Now if H&K would only put in a PAIR of FX loops, one pre and one post, everybody would be happy..... Laughing

    For those interested, I have been given a solution that does ^^this^^ by the engineer who designed the very amp in question. It`s a mod that can be done to the amp and is fairly easy. I will post my results after I`ve had a chance to test it for a while. (despite coming straight from H&K in Germany, it still voids warranty if that would be a concern for you)
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    bordonbert

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    Re: FX Loop question

    Post by bordonbert on Thu Sep 10, 2015 11:46 am

    Oooooohhhh!  Now that's genuinely exciting! bounce  Don't you dare dangle this in front of us and then never come back to it Jeff.  We can hunt you down you know!!! Suspect


    So does this idea make me an honorary member of the H&K Design Team then?  geek
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    VoodooJeff

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    Re: FX Loop question

    Post by VoodooJeff on Thu Sep 10, 2015 2:04 pm

    What it does is use the line out as a send (post effects), and the mod adds a return jack, also post effects (obviously). Being that the circuit is analog it`s really pretty simple (and reversible should you ever want to undo it). You end up with an insert circuit post effects.

    steve_napp

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    Re: FX Loop question

    Post by steve_napp on Thu Sep 10, 2015 3:54 pm

    2 loops, very cool, VoodooJeff!
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    VoodooJeff

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    Re: FX Loop question

    Post by VoodooJeff on Thu Sep 10, 2015 4:12 pm

    ^^ Smile
    The short version of the conversation went like this:
    "we put the effects post loop for the people using a distortion pedal in the loop. Pushing chorus or other effects into a distortion pedal wouldn`t sound good"

    "a valid point. However, the amp doesn`t really *need* a distortion pedal in the loop. That aside, when using a looper and losing the nice lush chorus and short slapback delay on the clean channel to no chorus and a longer tailed delay set up on the lead channel kind sucks"

    ".......we`ll get back to you"
    "........our engineer has found a way to solve that. Here`s the schematic. Enjoy your new feature"

    The folks at H&K in Germany were ultra cool about it and said the engineer even enjoyed the challenge.

    trifonius

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    Re: FX Loop question

    Post by trifonius on Sun Sep 13, 2015 12:34 pm

    That sounds really really cool. Please forgive me for being totally ignorant, but what does this mean in practice? What is a 'mod', some kind of device that needs to be purchased? How can i use this workaround?

    Thanks!!
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    VoodooJeff

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    Re: FX Loop question

    Post by VoodooJeff on Sun Sep 13, 2015 4:37 pm

    Mod is short for "Modification". It will entail a little bit of technical work, but nothing a good tech couldn`t handle in 30 minutes. The only part you`d have to purchase would be a switched 1/4" jack that will function as your return.

    As I sit here looking at the schematic, it looks like the solution they`ve given me is adding an insert jack. If you`re not familiar, an insert is a stereo (TRS, to be accurate) jack that has both a send and a return in the same plug via an insert cable (two 1/4" plugs into one 1/4" stereo, one is the send, the other is the return). I will message them shortly for clarification.

    trifonius

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    Re: FX Loop question

    Post by trifonius on Mon Sep 14, 2015 1:01 am

    Great thanks! So if i take the schematic to the tech service of a shop they can implement it?
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    VoodooJeff

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    Re: FX Loop question

    Post by VoodooJeff on Mon Sep 14, 2015 3:09 pm

    trifonius wrote:Great thanks! So if i take the schematic to the tech service of a shop they can implement it?

    Oh yeah, it will be a very simple operation for an amp tech. Not sure what labor rates are in your area but I`d be surprised if the procedure cost you more than about $60.

    trifonius

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    Re: FX Loop question

    Post by trifonius on Tue Sep 15, 2015 1:40 am

    And you will post the instructions? If so, you're a life saver!!

    trifonius

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    Re: FX Loop question

    Post by trifonius on Sat Sep 26, 2015 3:11 am

    Hi voodooJeff,

    Any news on this topic?
    Thanks!
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    VoodooJeff

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    Re: FX Loop question

    Post by VoodooJeff on Sat Sep 26, 2015 11:00 am

    I`m actually going to swing by the electronics store and get the piece I need on Monday,so give me a few days and I`ll have some news Smile

    trifonius

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    Re: FX Loop question

    Post by trifonius on Sat Sep 26, 2015 2:26 pm

    Thanks a lot! Smile
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    VoodooJeff

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    Re: FX Loop question

    Post by VoodooJeff on Thu Oct 01, 2015 11:15 am

    works like a champ. I`ll convert the PDF to something I can post here and anyone interested can see how it`s done. Keep in mind that despite coming straight from the engineer that designed the amp, it WILL void the warranty.

    trifonius

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    Re: FX Loop question

    Post by trifonius on Sat Oct 03, 2015 9:43 am

    That sounds great!!! Thanks so much!!
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    VoodooJeff

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    Re: FX Loop question

    Post by VoodooJeff on Sat Oct 03, 2015 11:11 am



    So you use a switching jack here. It taps into the outermost wire on the ribbon shown. Took me about 15 minute to get it to functioning condition. I still need to devise a permanent mount for the jack but it does work.

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