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JoeAArthur

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Posts posted by JoeAArthur

  1. Just use a SPDT toggle to switch between output jacks, or use a Gibson-style toggle in reverse if you want the option of running both at once.

    I'd use a DPDT toggle... using the other pole to ground the input to the amp I ain't using. An open input to an amp is only an invitation to create additional noise that you probably don't need.

    Edit dang it. A DPDT with a center off position. Either amp or both.

  2. I think it's an intonation problem, but it was fine before a few days ago AND CRUCIALLY when I play a top E 12th fret natrual harmonic, it is in perfect tune as when playing open string!

    Anyone have any idea whats up? Thanks guys!

    On any string, no matter how far out the intonation is, the 12th fret natural harmonic will always be in perfect tune with the open string.

    Compare the harmonic with the fretted 12th fret note. Adjust intonation accordingly.

    Edit for extra thought: Do you have a floating tremolo?

  3. Need help with this one. I installed 3 Red Lace Sensors in my strat. I have a humming noise now. Well according to Lace I cannot have 3 hot lace pickups together. They suggested I replace my middle and neck pickup to a lower output pickup to reduce noise. Instead of replacing the neck and my middle pickup can I just bring down the 15K output of the Lace Sensors using resistors? Or that will not work? Please HELP.

    3 Red Lace Sensor Pickups Single Coil size

    I've read this several times. For the life of me I can't come up with any reason (other than you might not like the sound) why you can't have 3 reds in the same guitar. Certainly no reason why having 3 reds in and of itself would cause you to have more hum.

    Do you have this hum in all pickup positions? If you do, then I would suspect something like bad grounding - like maybe the string ground is no longer connected. After all, one lace sensor ain't gonna know it's got two brothers when only one is selected.

    To answer your question about reducing output using resistors, yeah, you can. But the resistor would probably have to be a real high value to have any real reduction effect - like a 250K if your're using 250K pots would only reduce the output by 6db - like the difference between the #1 and #2 input jacks of a Fender amp. Trying to come up with an appropriate value would be a lot of hit and miss experimentation, and might even increase your noise.

    You could connect a trimmer pot internally to those two pickups in a volume control configuration.

    But I still can't see why having 3 reds causes more hum.

  4. btw, if anyone sees anything wrong with the diagram, PLEASE say so.

    I'm not sure if it is "wrong", it's just not the way I would wire volume and tone pots. It's just different and I was wanting to make sure you intended to wire them that way.

    I would have connected the output of the switches to the left hand terminal of the volume pot and not the center terminal. I would have taken the output to the jack from the center terminal of the volume control and not the left hand terminal of the tone pot.

  5. Crate's "shape" control is essentially the same implementation as Marshall's "contour" control on their ValveState amps. Here is a PDF of the schematic for the Crate VC508 which uses this same implementation as it's "tone" control so you can see how it's wired:

    http://www.stlouismusic.com/downloads/divi...08/25101H2_.PDF

    It wouldn't be a good choice for a guitar tone control unless you also install a preamp - the insertion loss of of this circuit would result in a loss of volume.

  6. Hello,

    I have an old Squire Bullet that was built with only one tone knob, one volume knob, the five position switch, and cord input where a second tone knob would normally be on a standard Strat. I have not had any luck locating the correct wiring schematic for this style. I tried Fender directly but they didn't even have anything. Is there a site where I could purchase this schematic?

    Can I assume you have three pickups? If so, then the wiring would be a strat with a master tone instead of the dual switched tone pots.

  7. IMHO - I'd find the best place where the pole pieces align with the strings.

    Pickup positioning by nodes has been discussed all over the net - but most ignore that when you fret a note all of the nodes change position - not to mention changes in node position as a result of intonation across the strings.

  8. Ok... I'll add my $0.02 to the original question.

    If you have a 60s era Vibrolux Reverb with a master volume control - it ain't stock. To me, that's enough reason to remove it. Fender only added master volume controls in the early-mid 70s and after 1968, all of those amps would have been silverface (not that it is a bad thing, just a fact).

    However, Fender did revert back to blackface cosmetics sometime in the early 80's. I think the Vibrolux did get a "pull-boost" switch sometime after 1976-77... but I don't have anything that proves it, but if you have a blackface Vibrolux reverb with a "stock" master volume control, chances are pretty good that it is one of the early 80 models, and not a 60s.

    Why remove the master volume on silverface amps.

    Several reasons. First, the master volume control as installed is a "loudness" design - there is a "bright switch" style cap that is connected to a tap on the master volume pot. This cap will boost treble at a low enough control setting... and cut treble when the control is above the tap point. Cutting this cap out will restore a lot of the "shimmer" found in the earlier non-master-volume amps.

    The master volumes with the pull boost amps introduced additional treble cutting networks. Some of these are not obvious... something like a resistor and capacitor in series IIRC. Removing these networks along with the master volume also restores a lot of presence to the amp.

    oops... ran out of change.

  9. you might as well be playing a Peavey Bandit™

    lmao! i liked those little amps back in the day LOL!

    well i do like tube tone, but i guess i am not what you would consider a purist. i like the tone that i am getting by using both a ss/hybred amp and a pure tube amp togather and would like to have the common features between the 2. so i guess the mod is possible, but not a recomendation for the tube purist ?

    has anyone here had the chance to use a marshall vs100(8100)? if you have ? you have to admit the amp does have good tonal quality and does have more warmth than a ss amp. grant it, it is no jcm! but does have a certain degree of warmth, not found in ss amplification.

    Ok... I'll bite.

    All you are doing with your modification is building a fuzz stompbox into an amp. Why not just use a fuzz stompbox in front of the amp? It'll be a heck of a lot easier... especially considering the errors in your hand-drawn schematic (e.g. where is the B+ coming from for the first tube stage?)

  10. The Gibson P-90 equiped guitars I have actually torn apart have all had 500K with 0.022 tone caps (one was an SG style, the other two were LP style).

    It's not really single-coil vs humbucking that makes the decision, and both Gibson and Fender have used both values - Fender even used 1 meg controls in Tele's for a while in the 70s - for both single coil and humbucker.

    For what it's worth, I base the choice on the impedance of the pickups... humbuckers normally have a higher impedance than single coils. However IIRC, P-90s have a coil resistance up around 8.3 - 9.6K range making them closer impedance wise to humbuckers than most single coils.

  11. I see. Some of the toggle style pickup selector switches do have 4 terminals with the middle two usually soldered together. So your 3 terminals and a ground only has a single terminal replacing the two in the middle. Not a problem.

    You can ground the toggle switch even if it doesn't show a connection on the schematic. Probably not necessary if the switch has a plastic cap, but if it has a metal tip I'd ground it.

  12. I have just ordered some new EMG active pickups for my Les Paul copy to replace the dreadful stock pickups that are supplied with the guitar. And whilst I have the guitar in pieces I would to modify the volume controls....... Something that has always annoyed me about les pauls is the fact the guitar has 2 volume knobs and when both pickups are selected you cant independantly adjust the volume of each pickup. This would be of great use to me because I think the neck pickup on the LP is far 2 a overpowering tone in contrast to the bridge pickup.

    However, I do like the sound of the neck pickup but think it would be better at 1/2 the volume. If I could lower the volume of the neck pickup independantly of the bridge then this would be a good thing.

    Ive played around with pickup heights and managed to take the edge off the neck pickup and I would like to go a step futher by modifying the circuit so I can independantly adjust the volume of each pickup.

    Iam have little idea of electronic theory but I can solder well and read circuit diagrams as long as they are well written and diagramed...

    Can anybody help with this?

    Open up the back plate and locate your volume controls. Of the three lugs, one will be attached to a ground, probably the back of the pot. Leave this terminal alone.

    Unsolder, reverse the connections of the other two lugs on each pot, then resolder. Presto - independent volume controls.

    Some gibsons (among others) come wired this way - it's the same as the volume control wiring of a Jazz Bass.

  13. Sorry, should have included the schematic, which has the values on it.

    http://amps.zugster.net/images/articles/to...s/fmv-schem.gif

    I was planning on putting this in a pedal form, not to be used as a stand alone preamp, as a kinda boost type thing.

    In that schem... the values of C2 and C3 are flipped. It looks like you might have copied them from Duncan's TCS - at least at one time he had them backwards. The current version has them corrected. You might want to download it to help experimentation with values.

    The tone control network is going to have some insertion loss. You might be able to make it up with the preamp's gain. Since you are planning on using it as a pedal, there is the option of sticking a volume control after the treble control output... and then adding another gain stage for recovery and buffering the output to the amp.

  14. So I have this here 'high gain preamp' schematic;

    preampsch.gif

    And I was wondering if I could add this tone stack design to it, and would it be a case of just sticking it on the back end of the scematic, like on the output part?

    http://amps.zugster.net/images/articles/to.../fmv-layout.gif

    If it's not as simple as that, or would work better before the gain stage, could one of you fellas gimme some direction on how to incorperate it?

    You could replace C2 with the tone network. Since the values for the tone network aren't given, you might have to scale them from either the Fender / Marshall / et al values. The output impedance from the preamp appears to be much lower than what you would have in an amp.

  15. ok, a buddy brought me an old gretch class a amp that he wants to barter for. he buys and sells guitars and amps for a living and got this one real cheap. he's not interested in keeping the amp but wants the speaker out of it to re-sell. it's an old hammond organ electromagnetic speaker out of the 60's. it's probably not the original speaker but the wiring to power it is. while researching the speaker i find that hammond says that it can be replaced in an organ with a permanent magnet speaker if a 700-ohm 20-Watt resistor is placed in the circuit.

    if i place that same resistor between the two wires that power the magnet in the speaker can i then install a regular speaker in the amp?

    Yes.

    You might pick up some additional hum as the electromagnetic speaker winding acts more as a choke than a straight resistor. You could use a choke instead of a resistor if the hum becomes a problem.

  16. So, I just bought a tube driven spring reverb unit from a Hammond organ. I understand that it's basically what was in the free standing Fender reverb units. There's an input and an output jack, two leads with male RCA connectors, and a power cord. I want to set it up as an external reverb for my Bassman head. The power is obvious, plugging into the courtesy outlet on the amp. I suspect the guitar would go through the input to output before going to the amp.

    Question is: How do I modulate the amount of reverb effect? I imagine I need 1 or 2 pots somewhere in here with caps.

    Also, what about shutting it off. Whould I need to disconnect the guitar and go straight to the amp...or could the signal go passively through the reverb.

    I appreciate ideas. (even if they involve giving up on the whole idea...)

    Best to all,

    H20

    Since you already have a reverb unit, you will probably want to build the circuit around it. Go to this site:

    http://www.accutronicsreverb.com/

    Input impedance is more important than output impedance, as the drive level to the reverb will have the most effect on how it will sound. Look under the "applications" section and try to determine the input impedance of your unit. The site also has various schematics for both drive and recovery sides of the reverb.

    Most shutting off thingies ground the output of the reverb, or the output of the reverb control. Reverb is not a "pass through" type of effect. A portion of the raw signal is mixed in with the delayed output of the reverb. By grounding the reverb output, then you are left with the raw signal.

    Hope this helps!!

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