FUCHS loop - a different discussion...

Discussion in 'Amps and Cabs' started by PeteSt, May 4, 2005.

  1. PeteSt

    PeteSt Member

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    Hello, all you FUCHS players! Here's an issue that I haven't seen discussed yet at all, and perhaps you can help me with your own views. I have a FUCHS modded Music Man head, and the huge problem I'm having with the amp's loop is the fact that the loop is AFTER the Master volume. This doesn't make any sense to me, and it's a big stumbling block for me, because as soon as you put any kind of outboard gear in the loop, changing the amp's Master Volume wreaks total havoc on the signal level going into the loop device(s).

    I need to use the loop in series mode, because I need to control the playing volume with a volume pedal, and any other outboard gear is mixed in (in parallel through a rack mixer). So the amp's own parallel mode is not the right solution.

    It just seems completely wrong to have a supposed Master Volume not be able to set your final overall "master" - "volume."

    The amp's manual says about "The Master Volume":
    "The master volume controls the overall level of the entire amplifier."

    In my somewhat frustrating experience with the amp, the Master Volume only actually "controls the overall level" when the loop is NOT being used. When the loop IS used (e.g. in series mode, with level setting outboard devices, such as digital gear), the function of the Master Volume CHANGES! It is now merely a secondary Loop Send control, which will directly affect the input settings of digital outboard devices, which, in turn, have to be continuously readjusted accordingly. Master Volume goes up, digital input has to be reduced to avoid overload. This also puts an artificial ceiling on the actual playing volume. It's NOT a "master volume" anymore!

    As a result, the amp can't get back to full operating strength (the full "no loop" volume), even with the Loop Return control cranked all the way. It’s a different amp that way, a much quieter amp. The Master Volume does now not "control the overall level". This is highly impractical and un-intuitive.

    FUCHS' own comment to this issue so far has been, surprisingly, just a "well, this point has never come up before..." (I'm wondering, how can it NOT come up! Shouldn't a Master Volume be the last stage in the chain?)

    So, have any of you had any experience with this issue? I'd be interested in your views.

    Cheers,
    Peter
     
  2. tone4days

    tone4days Member

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    hello peter

    i can't comment directly because i havent had the pleasure yet to play a fuch (amp or mod) product ...

    but i can sympathize with what you are saying ... what you describe is certainly reasonable and understandable as to why you'd want the master volume after the effects return ... it's a bummer that this hasnt yet worked out for you ...

    i have a suggestion that i hope helps you ... it works flawlessly for me in (as near as i can tell) a similar situation ... can you use a midi controller to control the master volume via a continuous controller on the effects unit output? ... i have a rack rig where i run series from the preamp to the effects to the power amp ... i use a midi foot controller to change the 'master' volume on the output of the effects right before it hits the power amp ... all my presets have the output of the preamp optimized to hit the input of the effects with best noise performance

    i apologize in advance if i havent understood your application clearly enough

    good luck
    t4d
     
  3. scottl

    scottl Member

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    I have never ever encountered this problem. In fact, I am able to run my rack unit with no issues at any level with any of my Fuchsen. Including mods. Furthermore, the Fuchs loop is inserted in the signal chain exactly where the loop is on Two Rocks, Skydstrup, Bruno, and the real deal Dumble (line out and return in that case). I don't think it is wrong. Pete, your loop is the full tube buffered job with trim switch? It should not be giving you a problem.

    Caveat is that I don't run in series mode. I run wet/dry/wet using my loop send to my rack and then out to powered L/R monitors. Much better tone that way. Why do you need to run a volume pedal in the loop? Why not run the loop parallel and use the volume pedal before the amp?

    Scott
     
  4. chedgeco

    chedgeco Member

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    I know this probably isn't a popular thing to do but it's somethingt that I do as well.
    The idea of the volume pedal in the loop is that you can dynamically control the overall level of the amp without affecting the input gain, like a foot controlled master volume. If you run the volume pedal before the amp it's just like using the volume knob on the guitar, which does affect the input gain.
    The later, in an overdrive channel, will not usually affect the volume level at all, just the amount of gain.

    There are other stage benefits as well. You can control solo levels, tune up quietly, as well as have a whisper quiet saturated lead tone for effect.

    I'm in agreement that a master volume control should not function as a effects loop send control. But then again, I'm just a Boogie user, although I do GAS for Two Rock, Fuchs, Rivera, VHT... etc. My 2 cents, and that's about all its worth...:rolleyes:


    Chris... :cool:
     
  5. aeolian

    aeolian Member

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    I understand the volume pedal bit. Folks like Gambale (and my local buddy Ken Harrill) use two pedals. One in front for the gain, and a second in the loop for the overall "master" volume. Very flexible set up where you can get distorted comp sounds at reduced volume, gain solo sounds on ballads, and work the dynamics of the whole thing.

    As for the loop/master thing. I know what you're talking about there as well. For me it's less of an issue as I don't turn the amp up and down that much. In fact it becomes a sort of an asset since with 100W the amp is too loud for most places I play in. When turned down low, there is some interaction between the master and OD out levels. At very low master settings, the clean will be louder than the OD even with the OD out dimed. This isn't as dramatic as on a Boogie where everything goes to hell when the master is below 3. My MusicMan mod is less sensitive than my ODS100 also. But I learned this trick from another local giant who plays a MkIII. By putting an effect in the series loop, you can turn up the amps master to where the interplay of the channels is where you want it, turn the effect input to an appropriate point, and then use the effect output as a true master volume. In your case this would be the mixer's output level control. I'd put the pedal before the mixer to reduce noise and inductive loses.

    With the +4/-10 controls (yours may be push pull on the effects knobs as on my mod, ask Andy) you should have plenty of return level to drive the amp to full volume and even more. One trick is to use the effects loop in series as an extra gain stage, whacking the output harder. Makes for a really fat tone.
     
  6. tone4days

    tone4days Member

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    +1 .. exactly why i do it ...

    t4d
     
  7. Fuchsaudio

    Fuchsaudio Member

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    First of all, thanks to everyone who stopped into the thread, including John Suhr.

    Here's my take on the purpose and function of a loop: A loop is a matching device to allow the interface of an outboard effect to and from an amp. It is located between preamp output and power amp input. The fx loop serves two purposes: Impedance matching, by providing a low send impedance and a high return impedance, it should match most any pedal or rack device, regardless of it being tubed or transistor. It's second function is gain matching. A pedal likes to run 200 to 500 mv (average), which is basically "guitar level". A rack device needs about 1-volt or so to properly operate. If everyone in the world had high impedance/high signal level effects devices, loops would be unneccessary.

    That said: The signals through any guitar amp will vary greatly from the guitar itseld, the tone controls, boosts, channel switching and volume controls on the amp. If the loop isn't there, and isn't being used, you'd adjust your levels through these controls only. An fx loop should also be operated unity gain when properly setup (IMHO). The input level from the amp, and returning from the effect should leave the amp at the same level as the amp is, without the loop being used.

    On some of our amps, an effects loop bypass function is provided (on the artist plus models). Some owners use the loop operating level (intentionally not set to unity) to change the amp level for solos, and returning to the non-loop level when the loop bypass is engaged.

    If the master volume were after the loop (for purposes of discussion) the levels through the effects would still move around during use. You'd simply adjust the final levels after the processing.

    As Scott said (thanks bud), during normal use, our loop has proven to work well with most any external devices. Once the signals to/from the effects are appropriate (at your maximum playing level) working down from that should not be a problem.

    I'll stand by my position that nobody else has complained about how the loop operates in the almost 5 years we've made it. BTW: The loop in production and modded amps is virtually identical. I'm always open to improvement's in our products as a result of customer feedback, but I don't see where this is necessary and why this isn't working out for you.
     
  8. Scrutinizer

    Scrutinizer Member

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    Peter, I share your frustration about the placement of MV in the Fuchs design. However, I have not had the problem you describe (weak return signal limits amp volume). The obvious solution to your problem is adding a clean boost as last device in your FX loop chain. This will act as your master volume.

    I have two Fuchs mods – a DRRI and a Traynor YBA1. I run the loop in parallel mode with a Replifex. The Replifex has a global setting that kills the dry signal, making this perfect for use in a parallel FX loop. FWIW, I have used this in series mode with acceptable results, but switched to parallel mode for reasons similar to what you describe.

    I have to be very careful when setting the input level of the Replifex. If I set it for maximum S/N before clipping at the start of a gig, a slight increase in the MV control on my Fuchs will drive the Replifex input into clipping. To prevent this, I set the input level on the Replifex very low initially, and use a compressor/gate/limiter before the Replifex as added protection.

    Another problem with the MV placement in this type of amp design is noise in the reverb circuit. At very low “bedroom” volume, the hum in the reverb circuit is very noticeable.

    Of course, it would be so much easier with an additional MV after the FX return.
     
  9. thelionsden

    thelionsden Member

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    If I understand you correctly this is the same setup as my Two Rock. It works fine. The master is essentially a loop send control. It raises or lowers the the clean and lead channel maintaining the relationship between the two that I have established with the clean gain and lead gain and master. I set the master so that the loudest of the two channels does not overdrive the input of my processor with the master acting as loop send and adjust my overall volume with a combination of processor output level control and amp's effects return level control as my overall global master. If your amp is not able to be made as loud with the processor in the loop either it ( the processor) is not capable of recieving as much input level as the preamp is putting out or it has no ability to make up the gain after it processes the signal.

    I just re read your post...Do you run the preamp out of your amp into your volume pedal then into the line mixer before returning it it to the loop return blended with the effects? If so, this would be where you would make up the gain...just turn up the output of the mixer until you get the desired result.

    If you want to run wet dry wet or dry wet, run loop send to volume pedal, split signal as it comes out of volume pedal, send one side to mixer and return the other to loop return. you can send as much level through volume pedal as you want to make the amp as loud as it can be just trim the input level at the mixer and make up the gain either with mixer master outlevel or level of amp used for wet spkr(s)

    Dennis

    P.S. If somebody already said this, consider it a very long winded "+1" :D
     
  10. aeolian

    aeolian Member

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    It sounds as if he is using the mixer as a "parallelizer" (as opposed to a paralyzer :) ) using the effects loop on the mixer to keep the effects as a sidechain, with the primary signal running though the main mix buss. There are some outboard effects loop buffers based on the Dumblator that can accomplish the same thing with much less bulk and waste of circuitry. What I can't quite figure is that the output of the mixer ought to be line level (+10 dBU) and be able to drive the output section of the amp to distraction regardless of whether the loop return is set on the -4 or +10 setting. In fact on the -4 setting, it ought to overload like crazy.

    I don't care for running everything though an effects box so I keep my amp on parallel, but it would be nice to have an overall master volume pedal.

    How about someone make up an outboard loop buffer with an optical or some other quiet level control and a CV connection to a pedal? It's a pain running the signal all the way up to the pedal board and back to the amp. Both noise in the passive volume pedal and signal losses in the cable. Such a gadget would eliminate this. Andy, if you make one, I'll buy the first (Scott you get the second ;) ) Fuchelator.
     
  11. PeteSt

    PeteSt Member

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    Hi tone4days,

    Thanks for your suggestion. My setup is a little different from yours, in that I'm using the loop of an amp head, not a preamp & separate power amp, and in that inside the loop my (loop) effects are all mixed in parallel to the straight guitar signal, through a separate rack mixer. The straight/dry signal is controlled by a volume pedal before it hits the effects. I don't actually mix dry and effects tones inside the effects units, so, compared to your setup, a continuous controller would only let me vary the *effects* level, not the dry signal itself.

    But more than anything else, in the case of the Fuchs, I'm having trouble maintaining precisely the optimized effects input level that you speak of, because of the Fuchs' inability to keep my effects inputs optimized AND let me adjust the amp's volume according to the needs of the moment, since the Master Volume is located before the loop.

    Cheers,
    Peter
     
  12. PeteSt

    PeteSt Member

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    Hi Scott,

    Thanks for your input. Yes, I do have the fully buffered loop, so that part is working well. I can see how you are not experiencing the same problem as me since you're running in parallel mode. At least your scenario is a little different, although I can see potential issues with that setup as well.

    I'm sure your wet/dry/wet setup is a great sounding rig. My reason for not running 3 separate speakers (in addition to rack gear, floorboard stuff & additional guitars) is mainly stage space, as well as number of channels that would need to be sent to the house AND be mixed by someone out of my control.

    The reason I'm running the volume pedal in the loop (or at least THIS volume pedal; sometimes I might have another one in front of the amp to control the front end) is that I want to be able to adjust overall playing VOLUME, without affecting preamp drive. This might involve volume swells or maybe playing very quiet while maintaining a consistent amp overdrive/distortion sound (disregarding pedals). A volume pedal in front of the amp would inappropriately vary the amp's drive up and down along with any volume changes. That's why I personally am going the serial loop route. The Fuchs is offering a serial mode if so desired, so it should be usable like that. But it's throwing me a bit of a curve while I am trying to use it.

    Now, even in parallel loop mode, such as in your case, I might expect possible level optimization issues along the lines of my original post. Because of the odd location of the Fuchs' Master Volume, I could see a player, say, in a band situation, needing to adjust his volume upwards on the fly during a gig or a show, and the Master Volume would also automatically raise the Send level into his outboard effects, which could potentially make the processor(s) clip in a pretty bad way. To remedy that he would have to also adjust all his effects input levels (on the fly!) to get them out of overload, while probably also losing his 'correct' balance between dry & wet.

    In a serial loop amp I'm aiming to adjust the overall volume, up or down, without affecting optimized levels. Most master volume amps that I've played do that. The Fuchs doesn't. Now, Scott, are you saying that Two Rocks, Skrydstrup, Bruno, and the real deal Dumble all indeed adjust the master volume BEFORE sending a signal to the Loop Send? If that is indeed the case, I'd have to ask a big WHY??? What is the amp maker's logic of not allowing control of the overall loudness of an amp, AFTER achieving an optimized 'effects sound image' and without fiddling with all the carefully tweaked previous signal levels all over again?

    If it's indeed a fact that, say, the famed Dumble is actually showing the same, in my eyes, detrimental trait under discussion here, it's just lost some luster in my eyes.

    Scott, I truly appreciate your input. If you have any further thoughts I'd love to hear them.

    Cheers,
    Peter
     
  13. PeteSt

    PeteSt Member

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    Sorry, back in the game a little late. Thank you all very much for all your comments.


    (Underlined emphasis mine).


    John, yes, that's what I would like to see.


    Exactly. Volume pedal in front of that, for volume swells & dynamics, (therefore series loop mode), and 3 choosable rack units, 100% wet, in parallel.
    Yes, that's basically how I'd currently be running it. The line mixer's output level is what has to make up for the lack of a true master volume on the amp. Basically I have to crank it to the max to even get close to what the Fuchs would put out without the loop.
    Without level setting devices in the loop this is indeed an impressive option.
     
  14. scottl

    scottl Member

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    Thanks for the detailed response Pete. Yes indeed the other amps put the loop between the master and Phase Inverter input. The Dumble has a post master line out and a return that is pre power amp. Dumbleators are interfaced in this position.

    I wonder what the potential tonal pitfalls are of interfacing the loop before the master? I wonder if the load will seriously affect the tone of the preamp stage that feeds it.

    Btw, try using a reverse speaker cable to invert your amp output. It does make a huge difference on the tone. Try it...

    Scott
     
  15. PeteSt

    PeteSt Member

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    Hi Andy. Thanks for jumping in, too. Yes, playing levels will certainly jump around a bit as you play. You'd have to find an optimized level setting for the loop without clipping and then go with it. Once that is done, I would indeed want to simply adjust the final levels after the processing, without, however, affecting that carefully tweaked loop level.
    Hmm, I'm not sure how I can make my point clearer to you.

    The amp has a control labeled Master. But as soon as I use the loop it simply isn't a Master Volume. It's suddenly a (basically redundant) secondary Loop Send control. The "master volume" function, however, has just disappeared on me. The dry amp has the pot labeled "Master" to achieve all kinds of drive and volume things. The series loop amp (with level setting devices) can enjoy no such function, because anything the "Master" does will have to be counterbalanced and negated by other input level setting controls to keep the input levels healthy.

    As far as putting pedals in the loop: I think I'm gonna leave that one alone, since I would rarely use it like that (maybe a rough 'n' ready club board thing with a delay pedal in the loop...). I'll simply point out that in that instance there wouldn't even be a mixer gain stage in the picture to crank the much lower level necessary for a stomp pedal back up to overall volume/master volume needs.

    In fact, Andy, the function of the push/pull on my Loop Return control still eludes me. At first I thought this must be the switch to adjust levels for pedal or rack equipment, but all it does is reduce the Return level, making the amp softer, while the Send level remains the same in both positions. So it's not changing levels going into a theoretical floor pedal. Can you shed any light?

    Cheers,
    Peter
     
  16. thelionsden

    thelionsden Member

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    Any master volume is always going to adjust the level of everything that has come before it right before it hits the poweramp section of the amp.. Thats what a master volume does. Power amps sections are running wide open and are dependent on the input level as to how much volume the amp actually puts out. The master sets the input level of the power amp allowing you to have higher preamp settings to create different tones at lower volumes than the amp would produce without it. The effects loop is placed after the master volume because this balance that is set up before it is also the best signal to feed effects with. if you have to lower this to feed effects than you have to make up the gain after the effects. Once you get this set for the best input level to your effects you don't touch it anymore. That is what the effects return level control is for. You have to make up any gain after this with the effects return or your mixer output level. If you are insistent upon having every effect optimally trimmed to the 0vu on the level indicator, which is not necessary really you will have ot use a mixer with auxes and return the effects to channels so you can set the input level as hot as you want and then raise or ;lower the sound of the effect with the mixer fader or knob that that particular effect is returning to. The master mixer out will then control your overall bgain that you will be sending to the wideopen poweramp into the effects return and also its corresponding control. The Master is really only an overall amp master when the loop is not used. As soon as you use the loop, the return level control becomes this instead. If as you said youhave this all the way up and it is still not loud enough, turn the mixer output up. And turn it up enough so you don't have to run the return level all the way up.
     
  17. PeteSt

    PeteSt Member

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    That's where our opinions seem to diverge and what has me puzzled. I'm looking at 3 amps right now that have the master volume after the loop, not before (a Boogie Mark III, a Matchless SC-30, and a Naylor Super-Club 38), and while the loops are a little different from each other in quality, they each allow me to use the same handy Master volume control after the set-and-forget loop that the completely dry amp would, enabling me to simply adjust overall playing volume if needed. (Not that I would prefer to use, say, the Matchless with a loop setup, but sometimes I might need to).
     
  18. PeteSt

    PeteSt Member

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    Would that be the same effect as, say, switching the speaker polarity on the back of a Matchless? I'll have to give this another listen...
     
  19. thelionsden

    thelionsden Member

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    If that is the case with these other amps, what controls the output level to the effect? If you just allow your mind to think of the effects return as the handy master then it is the same thing. With any good loop it is likely to have a send level control of some type and a return level. Doesn't matter what they call these controls they are still going to be there and they are still the same. . It seems you are locked in to the idea that the one that says "Master' on the panel has to be the global overall level. Let that thought go. If want to control it after the loop, use the return level. if you want to control level before, use the send level control, which in this case happens to say master on it. If your effects are lowering your volume levels too much because of their input sensitivity, you can solve that with either a different higher quality effect that is capable of recieving greater out put of your loop send and subsequently putting out more level, your effects output level control if it has one, mixer output level, or effects return level. You have the ability to make it work at your fingertips but you have to open your mind to thinking about it for what it really is and using it accordingly. I had a recording studio for a long time with a huge Neve console so my mind is used to thinking in terms of balancing gain structures to achieve the desired result. There is more than one way to skin this cat.

    Blessings

    Dennis
     
  20. chedgeco

    chedgeco Member

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    aeolian,

    Digital Music Corp use to make exactly what you are talking about. It was called the System Mix Plus. In a series effects loop, it would allow you to run your effects in parallel and it offered a stereo VCA that could be controlled with a remote continuous controller.
    Link: http://www.amptone.com/dmcsystemmixplus.htm

    I was going to buy this just for the stereo VCA until I figured out that my TC G-major could do this as well. Thinking back I wished I had bought it because they don't make it anymore.
    I still do the volume pedal trick in my Mark III rig, but I don't use any effects with that rig and I only use that rig for rehearsals.

    Chris... :cool:
     

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