Granger Effects Loop?

Discussion in 'The Workbench' started by Gene Ballzz, May 15, 2018.

  1. Gene Ballzz

    Gene Ballzz Well-Known Member

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    Hey Folks,
    Has anyone here had any experiences with the "Granger Ultimate Effects Loop" as opposed to the "Metro Zero Loss" unit? It seems to boast a feature or two not incorporated on the Metro. In a lot of ways, they "appear" similar, but I realize appearances can be deceiving.

    http://www.grangeramp.com/ufxloop.php
    http://grangeramp.com/shop/index.ph...id=482&zenid=9b88c3ebedbfdc1b1f89a295416ee435

    Thanks Folks,
    Gene
     
  2. Gene Ballzz

    Gene Ballzz Well-Known Member

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    Well,
    I guess if I try one, I'll be the first and should report back here to answer my own questions? :nuts: My biggest concern is drawing down the voltage past where I tie the power supply in. I guess a fully detailed voltage survey is in order beforehand and then adjust the B+ string to compensate for any loss?
    Thanks Gene, :lol:
    Gene
     
  3. chuckharmonjr

    chuckharmonjr Well-Known Member

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    I havent tried one myself, but I can personally vouch for Mark and the guys. First class outfit.
     
  4. RickyLee

    RickyLee Well-Known Member VIP Member

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    I have a few models/project amps I have been wanting to try the Metro No Loss loop on. I do not know the price difference between the Granger loop and the Metro one, but I know that I am now wanting to try one of these Granger kits. Would you know the cost on the Metro one?

    I have purchased Granger relay coil/channel switching boards and they are top notch and very reasonable priced. And their customer service is top notch as I did encounter a bad relay coil on one of their kits. They sent me the replacement pronto no questions asked.
     
  5. Gene Ballzz

    Gene Ballzz Well-Known Member

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    Metro is only $5 more, though who knows about shipping. I like the Granger's feature of having the level pots accessible through the jacks with a small screw driver, as well as the option of the bypass switch mounting either remotely or on the board. It does seem that the Metro loop draws down the voltages downstream from where it's power gets tapped, even though it claims only 1.7 ma of current draw and I can only surmise the Granger unit does the same/similar. Metro discusses how to address this voltage issue near the end of his instructions. Metro does offer a disclaimer concerning his design was intended for some specific Marshall amp models, but alludes to it having been successfully in other amps and ways.

    https://store.metropoulos.net/products/zero-loss-fx-loop-kit

    Gettin' Loopy!
    Gene
     
  6. ampmadscientist

    ampmadscientist Well-Known Member

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    I haven't tried the granger, but I just finished my first Metro.
    The price was just about the same, I went with New Religion's recommendation.

    The level pots adjustable thru the jack holes: that's a brilliant idea. +1 for the Granger!
    (NOTE) I would rather have 5-10 turn precision pots instead of the single turn consumer grade pot...I would have paid extra for it...but, I can still change the stock pot.
    A better pot (10 turn, metal foil precision) would have cost $10-15 more.

    The wire (included) was Beldon, but it was lower temperature, foil shield, PVC covered. I would have used better wire, and I recommend you do. The wire included was "OK," consumer grade. I would use teflon, or silicon covered wire, with a braided shield, mil spec, aircraft grade, which is much more time consuming and expensive to install. BUT: I would rather use mil spec wire.
    I do not use PVC wire in guitar amps, normally.

    Jacks: do not appear to be real Cliff jacks. I can take them out and install better jacks. I would have used real Cliff UK jacks. Minus -1 for Metro. Sorry, I don't like the jacks. I want jacks with solid nylon construction.
    You can keep the knock-off jacks. Gimme real Cliff UK jacks.

    The resistors: were metal film, audio grade, 1/2 watt. At least they didn't use carbon resistors (thanks). Using better metal foil resistors would have cost considerably more money.....but I might be tempted to do that.

    Both units appear to use high voltage FETs...the nominal input voltage was about 300VDC. The Metro units have 1 on-board filter cap. (22 uF 450V, 105C)

    I tapped the DC power off the phase inverter, using a 47K 2W metal oxide resistor (resistors were included). Several resistors were included to give me many DC adjustment options. (+ 1 for Metro !)
    My final input voltage was 280VDC...the max input recommended was 300VDC.

    Bypass switch : I don't need no stinking bypass switch...
    besides which, the switch included was a consumer-grade mini toggle switch. I don't even "want" to use that. I would have used a much better switch (which also costs a lot more).
    I don't need any extra hole in the chassis.
    A better switch would have cost about $10 more.
    But: who cares about the switch, when I don't need the switch at all? So, screw it. Forget the switch.

    Using just the Metro board: you don't need the switch at all, really. The jacks on- board have switch contacts to break the loop when the plugs are inserted !
    I don't care about "bypass..." I just leave the loop in at all times, and adjust the circuit for it. Screw it.
    If I need bypass - I will just plug in a cable, and bypass the loop.
    (you do what you want)

    POWER UP:
    The circuit is very low drain, and does not cause a considerable voltage drop from the phase inverter node. I had no surge problem, the Metro board charges up slowly to the full 300 volts DC. It took about 10-15 seconds to charge up to full voltage utilizing the 47K 2W dropping resistor.
    (I did the slow-start, less -than -maximum voltage deliberately, just to give those 2 transistors some breathing room)
    So far, the on-board filter capacitor seems to store more than enough reserve charge to run the loop.

    NOISE: This is what I did beyond a normal installation:
    I used regulated DC filaments for the preamp tubes, and used regular AC power for the PI.
    I used a swing choke for the entire B+ DC power supply.
    Using this setup, I had only a small amount of hum increase...very slight...when comparing to loop VS. no loop. I did not have an issue with buzzing or hum (added noise was tiny - very tolerable).

    Obviously, the Metro board is well designed- adding only a very small amount of noise.
    (provided the AC filaments are separated some distance from the loop board !)

    SOUND CHECK:
    The loop passed a clean sine wave (scope test).
    The loop sounded transparent (did not add objectionable coloration to the tone). Even with no bypass switch : it sounds pretty clean by itself.

    Metro Overall Rating: 8 out of 10. I like it, and it's a good board for $70- I thought it was worth while.
    Now Give Me:
    Silicon Wire, 10 turn precision pots, and Real Cliff jacks.
    I would pay more for it, gladly.
    I would have paid $100 instead of $70, happily.
     
    Last edited: May 18, 2018
  7. Gene Ballzz

    Gene Ballzz Well-Known Member

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    AMS,
    Thanks for that! Lots of good details/tidbits, I'd expect nothing less from you! :cheers: As for the bypass switch, the only real use I could see would be to ascertain unity gain (or the relation to it) of loop present/not present.

    Now, if you were to install this in a generally stock 5E3 Tweed deluxe, where would you insert it in the signal path to ensure being as late in the path as possible? For my personal use, it seems the later the better, as with time based effects, the more fully "developed" the sound is at their input, the better. In the following diagram, many suggest the loop in the location labeled "Passive Effects Loop" but I think the "Zero Loss" location may be better. I've had comments that at the "Zero Loss" location there would be substantial "bias voltage" present, but I don't see where it would be coming from?

    Thanks Again,
    Gene Deluxe-5E3-schematic copy.jpg
     
    Last edited: May 18, 2018
  8. Gene Ballzz

    Gene Ballzz Well-Known Member

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    Ahhhh, now I see where that "substantial bias voltage" would come from. From the cathode, of course! DUH! :facepalm: That brings up the question about sort of "isolating" the loop by means of an additional cap at the output of the loop? Would it be best to split the values between the one at the input and the one at the output (.047 in & .047 out), or would I likely be fine just using another .022 on the output side to block that DC voltage from the loop's signal path?

    FWIW, mods on my 5E3 are fairly convenient, as I used turret board construction, with all connections (even the jumper wires) done above the circuit board!

    Thanks Again,
    Gene
     
    Last edited: May 18, 2018
  9. RickyLee

    RickyLee Well-Known Member VIP Member

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    @Gene Ballzz: I would think the dual caps would work for isolation. I am trying to remember values I used on my Deluxe Reverb as well as a project amp with a cathodyne; both of those amps have a pre phase inverter master volume.

    My idea is to just usually keep that first cap value the same, then find the biggest value cap possible at the outgoing signal side. And then you do not have to worry about cap voltage value on the outgoing as the first cap is blocking the high voltage DC. I think I might have used a .22uF or .33uF cap that was 75V rated. An old Orange Drop or something along those lines.

    Obviously, when you get to a big value mylar type cap, the physical size goes way up. And I am thinking you were on to what my thought process was when having the two caps in series, you then have a value drop there. That will only happen in my case with a master volume if that MV is set to max 10. On your loop, you might have the two caps in series if the loop is bypassed.

    I want to try one of those loops on my Deluxe Reverb. So I will be trying to mount it similar to your setup. I like my loops just before the power amp/phase inverter. But then for my Deluxe Reverb, that will then mean my reverb will be in the signal path before the loop. I like my reverb at the very end of the fx chain. Of course, I could use a reverb pedal but then what is the use of having that sweet Fender natural built in reverb . . . .
     
  10. Gene Ballzz

    Gene Ballzz Well-Known Member

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    All very good points Ricky and well taken! :h5: I have one on the way and will inspect to see where those caps are in the loop circuit. You may be absolutely spot on with the thought of them being all that's needed? :hmm:
    Thanks,
    Gene
     
  11. tschrama

    tschrama Well-Known Member

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    That preamp stays cleans.. the power amp will distort first and needs a high voltage swing to the PI. I am not sure the FXloop is suitable for that amp.. or if it will give you any benifit.
     
  12. Gene Ballzz

    Gene Ballzz Well-Known Member

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    I've considered that. This is why I want to experiment with it in the least invasive manner. If it works well, I'll drill and install it as a permanent fixture. If not I'll remove it and it will be like it like it was never there. I built the amp and as mentioned, all connections are on turrets above the circuit board. I could likely even do a test install without taking the chassis out of the cabinet, though it WILL come out to the cradle and bench! And FWIW, I use a 12AX7 in V1, instaed of the specced 12AY7, so there's a "little" dirt in the preamp, although I suspect not very much!
    Thanks,
    Gene
     
  13. tschrama

    tschrama Well-Known Member

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    Since there is no MV before the PI, the power amp will allways distort way before the preamp does. It has nothing to do with the gain or tubes of the preamp.

    But if you are gonna experiment with a FXloop before the PI, you might as well install a MV just before the PI and achieve some preamp overdrive.

    besides all this.... the metro kind of FXloop introduces no less than four high pass filter poles and sends the signal through a 2M2 resistor causing hiss and making vulnerable to pick all kinds of signals.
     
  14. ampmadscientist

    ampmadscientist Well-Known Member

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    I'ts gotta be in the zero loss location of course. You gotta use 2 coupling caps, one for the output of V1A and one the input of V1B.
    The board does not have coupling caps per sey.
    Levels:
    The on-board level adjustments don't offer too much flexibility, and you and I will change the input/output gain to match the needs of the amp.

    (I found this was absolutely necessary)
    I couldn't match the return level to high level effects pedals. I was given a choice of: (switch only)
    A: 1/2 volt PP at return drives PA to full output (switch is in +4 position).
    B: 150 mv PP dives PA to full output (switch is in -20 position)
    AND these levels (of course) depend on the amp design. Different amp is a different story.

    SO my high level effects pedals are unity gain, 1 volt in = 1 volt out, etc. Will not match the Metro effects loop.
    The return input (as-is) is too sensitive and has no pot to adjust the level. (the pot is for the send level)

    I came up with this solution (on the fly):

    metrozLE.png So far, by changing the input / output gain resistors, it looks like I can get the return level to accept a high level effects pedal (1 volt or more level into the return without overloading the PA).
    It's going to take some trials to get the ratio just right.
    And also: when I un-plug the effects pedal, I want the loop to pass (more or less) stock level into the PI input.
    (I'm not using a bypass switch).

    Seems like (so far) if I increase the input gain resistor and decrease to output resistor, I can then get the levels somewhere close to where I need them.
     
  15. ampmadscientist

    ampmadscientist Well-Known Member

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    "...no less than four high pass filter poles and sends the signal through a 2M2 resistor causing hiss ..."

    I find no such circuitry in the Metro loop board I purchased. (2) there was no hiss problem, even with my ridiculously high gain and outrageously increased impedance.
    (impedance to the outskirts of infinity).

    Sorry, not getting that problem.
     
  16. neikeel

    neikeel Well-Known Member

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    Are we talking about the same product?
     
  17. Gene Ballzz

    Gene Ballzz Well-Known Member

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    FWIW, the one I'm going to try first is the Granger unit. Luckily for me, a friend bought one and never used it and is simply sending it to me for testing and consideration. I think the in & out level pots may somewhat alleviate the issues that AMS has experienced. I still think that the biggest question I need to answer is whether or not the overall sound and character of the signal/amp has been developed enough for a loop to have any real use in this amp! If it makes effects used sound and react the same as they would in front of the amp, then the loop in this location is totally useless, IMHO.

    I will snap some detailed pics so that we can all compare the differences and similarities of the Granger vs Metro.

    Thanx 4 All The Comments, Tips & Thoughts,
    Gene
     
  18. RickyLee

    RickyLee Well-Known Member VIP Member

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    I am thinking I will place an order for one of these Granger loop kits, as I was wanting to order another of their relay coli boards anyways. I more than likely will try this loop kit on my Deluxe Reverb. But keep in mind, my amp has an added master volume. And then my preamp has options to get very saturated into Marshall/Mesa territory.

    You are referring to the Metro board?

    I have been wondering about the signal path and if it goes through any solid state devices/transistors ect. on the Metro loop as well as this Granger loop. Obviously, be able to bypass the loop is a plus. And then if we are running FX devices into the loop, we are running into solid state devices there. But I like to keep my loops as pure as possible.

    I am also wondering if both of these loops require 12AX7's to operate?
     
  19. Gene Ballzz

    Gene Ballzz Well-Known Member

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    They do not require any tubes for operation, as they have transistors/op amps (depending on model/brand) to do that duty. And yes, when active, your signal certainly is passing through/amplified/buffered by solid state devices. I don't see this as much of an issue, give that nearly all effects devices are "loaded" with solid state stuff anyway. From thr hype, the loop makers claim "transparency" which would lead me to hope for no actual change in sound/tone other than keeping it at optimum signal operating levels. Remember that the mic you put on your guitar speaker gozinta a solid state mixing console and gozouta that through solid state EQ's, other processing and solid state amplifiers before it goes to the sound system speakers! The only place where solid state stuff is really crap is in the creation of distortion, tonal color and dynamic push/pull feel. On the other hand, solid state devices sure can't be beat for pure, uncolored, unadulterated, amplification and reproduction of sound.

    Dropping A Turd Into The Pool!
    Gene
     
    tschrama likes this.
  20. tschrama

    tschrama Well-Known Member

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    Which makes this 'zero loss' fx-loop thing such a backward design. Here single ended MOSFETS are used to emulate tubes.... in about the same way as real tubes would be used. Dynamic range is thrown away for no reason + these devices in the way they are used need extra capacitive coupling causing 4(!) high pass poles. Feedback is being used to lower the output impedance which would be outrages without it... it is such a weird design.. yet very popular somehow.
     

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