JoeAArthur

It sounds to me like your ground and output connections on the blend pot are reversed. If these two connections do indeed look the same as the stewmac diagram, reverse them anyway - not all blend pots are created the same way.

This should help: http://www.seymourduncan.com/support/schem...h_2v_1t_3w.html

Yes, it is possible for a humbucker to be out of phase with itself. Switch the connections for the black and white wires. Try one first in humbucking mode. You should get your bass/volume back. If so, do the same with the other pickup.

Gee... is this what I am going to be like when I get old? Hey hold on a second... I'm already old!! <hee hee> I'll always consider getting older an advantage compared to the alternative!! Good luck!! Joe

Your circuit looks good, but the only thing I can't verify is that you have the pickups themselves wired correctly - you didn't mention what pickups they are, or if they're both the same or different manufacturers. Color code does vary. It does sound like from the symptoms that it is a pickup phasing problem. edit: Oh and yes, your diagram does have the pickups wired "interactive" which means turning down either one all the way will silence the bass. Switch the leads from the hot and center terminals of both volume controls to make them non-interactive - as much as possible with a passive circuit that is.

Could you state that as a question? Your P90 should have two wires. One goes to the 3-way selector switch - the one you have open, and the other to the back of the volume pot. Which wire goes where depends on the phase of the pickups and I'm afraid I can't help you there. The bare wire on an SD humbucker is the ground.

GFS pickups use high quality materials. Their price is lower because the labor is Korean. The single coils are supposed to be hand-guided, and if that is true, those Koreans can really lay down an incredible coil. Higher price doesn't always mean higher quality. But if you believe the opposite, buy a boutique pickup from some guy that winds pickups in his garage hoping you will think his inept and sloppy winding "process" has some sort of magic that will give you "the sound" you have been looking for. If you pay enough he might even sprinkle it with pixie dust to insure it. Hey, you never know - the planets may just be in that correct alignment for it to happen. But if that were true you may be better off buying a lottery ticket. But it's your call. Any rational approach on this subject is never going to happen, and on the internet it will always be deemed personal preference so as not to hurt feelings - and that's what keeps the "less than adequate" in business. And I can say this because I have paid my dues, paying for pickups that don't deliver anything except the name of the maker.

This isn't an answer and it will probably only add to the confusion. On the first 15-20 years or so of Strats, the polarity of the pickups was the same and nobody complained. Then the middle pickup became RWRP to provide a humbucking effect in positions 2 and 4. Again, nobody complained. With dual humbuckers, the traditional wisdom has been to turn them so that the two polarities facing each other in the middle are the same. The reasoning is that like poles repel each other and therefore this should prevent magnetic interference. Nobody complained. However, as psw pointed out - the two coils of a humbucker have opposite polarities right next to each other, and there are guitars with one humbucking pickup - and again, nobody complains. Now I haven't done any sort of scientific study on it, but to me that last case of opposite polarities right next to each other would be the worst case. If you think about it, the concentration of magnetic field would be at the top of the poles of each coil, in the field of the string vibration, but very little magnetic field would be going down to cut across the windings of either coil between the two coils. The magnetic field that does cut through the coil windings to produce the output voltage would be on either outside of the humbucker. This could suggest a reason why a split coil humbucker doesn't really sound like a single coil pickup. But nobody complains. Bottom line, if nobody complains with all possible combination of polarities, then maybe the polarity relationship of adjacent pickups doesn't really matter - no matter what the theory.

I'm planning on dropping in a couple new pick ups into my Epiphone Dot in the next few weeks. I'm going to split a humbucker at the neck (SD Stag Mag with an on/on/on switch) and a Humbucker sized P90 from guitar fetish. It is only a single tone, single volume. What value would you recommend for the capacitor? As it stands now I was just thinking of leaving it with the stock cap on it. A wise choice? The cutoff frequency of a cap is dependent on two thingies (yes, that is a technical term) - one is the value of the cap in farads (or microfarads as is normally used in guitar circuits) and the output impedance of the pickup. These two values make up the primary determining characteristics. Although many will argue that the resistance of the "pots" mean something - at best concering a treble cut tone circuit, can only determine the depth of the treble cut - it has nothing to do with the -3db frequency or where the cut actually starts. The higher the pickup output impedance, the lower the value of capacitor is needed to maintain the same frequency of cuttoff. That's why lower output impedance pickups, like single coils, usually use a higher value of capacitor (e.g .047mfd) than higher output impedance pickups like humbuckers (e.g. .022mfd). There is no magic number, and very few pickup makers even give you their product's output impedance. Note: DC resistance of a pickup is not related to the output impedance of that pickup. It just happens to be the easiest thing to measure. As with everything on the internet - it will all resolve down to being something dependent on "personal preference" - so go ahead, and experiment - it can't hurt anything. I'd suggest a .022mfd.

Thank you unclej... glad it all worked out!! To paraphrase an old TV show - "I love it when an amp comes together!!" The board number is not the amp model - and that board was used on a number of amps with different model numbers. It's a good bet that the "D" portion is a modification or version number. If your amp is the head version like mine as pictured here: 1982 X-100B, X-60B Then it would be an X-100B. Or an X-60B depending on power output. The "B" stands for British because these amps were built upside down and therefore backwards. Not a slam on the British, just what happens when you take a fender amp like a 1959 bassman and flip it upside down, put it into a head and call it a Marshall!! If yours is a combo version, then check out this page: 1982 Carvin Combo's If you want a schematic, PM me with your mailing address and I'll send you a copy - it's from 1981 which was the only copy they had. I got mine from Carvin many years ago but it was like pulling teeth to do it. Apparently the existing staff doesn't know much about their history, so when I asked for an X-100B schematic from 1982 they sent me one for the newer version that uses op-amps in the preamp for tone control. I think that newer model came out in 1984, using a 3-volume instead of the 4-volume setup like our amps. BTW - this amp is very similar in design to the Acoustic 160 series of tube amps. Ok... end of rambling... for now at least!!

+1

I haven't tried one but I've heard they are supposed to be good - Dimarzio makes a bass version of their high output X2N... called the X2N-B.

The amp sounds like one I have, one of Carvin's older X-series from the early 80's. Mine is a head which is in a really huge case, has 3-12AX7s and 4-6L6GC outputs (making this an X-100, there was also a X-60 and an X-30 version). Besides the controls you mention, it has bass, mid, treble and presence... a graphic equalizer - with a eq in/out switch next to the power and standby switches, and the reverb knob is located on the back of the chassis. It has 3 footswitch jacks - vol boost, reverb/eq, and lead... preamp out, power amp in jacks. A 60% power switch, two 4 ohm and one 8 ohm speaker jack, and a slave output with level control. Does this resemble your amp in any way? If your amp has reverb and the pan is unplugged, make sure the reverb control is off - you can pick up feedback when the input to the recovery amp isn't correctly loaded by the pan. Those resistors coming off the volumes are for extra attenuation of the signal and shouldn't be causing your feedback. Off the lead master should be a resistor/capacitor combo - a 180K (brown, gray, yellow) with the cap being either a .001 or .0022 that goes to the switch - this provides the high boost.

The wiring on the left is only a variable resistance - it's voltage divider characteristics depend on the input impedance of the amp. You will never get a total volume cutoff. If the pot value is 1 meg and the input impedance of the amp is 1 meg (typical tube Fender) then the most volume reduction that can be achieved is 1/2 or 6db. If you do have a typical tube Fender, that is the same volume difference as switching the plug from the #1 jack to the #2 jack.

Do you mean "braided wire" where it looks like a bunch of individual wire strands braided along the outside of the wire? If so, the "cage" is a shield ala faraday. I believe SD pickups use a foil shield inside the outer plastic insulation - that bare wire, the un-insulated and un-colored one is the ground that contacts the inside foil. Just ground it.

With that pot you'll get even less than what you're getting with the other!! That is definitely wrong. If you hold the pot as it's pictured in the diagram you posted, the top section should measure 500K from the center to the left and ideally zero from the center to the right. The bottom section should measure the exact opposite - ideally zero from the center to the left and 500K from the center to the right. Your volume and tone wiring sounds fine to me. (note to self: never buy a blend pot from Stewmac)

Hmm, that's interesting. Based on your two values I would expect around 4K at the center. Assuming you didn't nudge your volume control down accidently when you took the center readings, about the only thing it could be is a problem with the blend pot. I'd measure the blend pot with it set to the center detent. Measure the resistance of each section, from the center lug to each of the outside lugs. On one lug you should be getting the reading you got for the pickups and on the other lug you should get ZERO. If the tracking of the resistance element is off at the center, you'll get something besides zero on the lug where it should be zero.

You'd remove knobs but not pots? That would look pretty weird. Pickups do not need to be "pre-loaded" by a volume pot, and yes they can be hooked straight into an amp. The input impedance of the amp would be in parallel with any volume pot if used. Haven't you ever heard of a "blaster switch"? It connects the pickup (usually your lead or bridge pickup) directly to the output jack bypassing volume, tone, pickup selectors - everything. Full output... with the pickup loading being the input impedance of the amp.

Well I guess if you are going to remove volume and tone pots, then instead of using a push-pull pot, just stick a switch in the hole. With the right washers a mini switch could be installed. How many holes for controls are we talking about in this guitar anyways?

This link should help you wire up a blend pot Blend pot wiring What crafty is saying about the switch - it doesn't have the right wiring capability to have the pickup be series humbucking in the middle (or any) position. Parallel humbucking would be possible, but it's probably not what you want as the difference in the positions sound wise will be subtle. His suggestion would give you two different sounds instead of three pretty much the same sounds.

If you hear the sound of the tubes rattling being amplified through the amp, then yes it is definitely a sign of bad tubes. If you don't, it could be the preamp shield covers are loose, old, worn whatever. Quality of tubes has been going downhill. I went through 4 sets of 6V6s before I found one that didn't rattle.

No, no, no, no, no - you are not telling me WHAT it is you wanna series/parallel blend. For example, if you told me you want to series/parallel blend in the middle pickup ONLY - it would be relatively simple to do something like: Three way switch - selects neck, both, bridge pickups Master volume Middle pickup series/off/parallel blender knob Master tone I know you want a blender - I know you want a master volume and a master tone. I don't know WHAT you want to blend and WHEN you want to blend it.

Looks to me like it is a head version of a Deluxe Reverb. Sure, the tube complement is all wrong, but that mix of tubes sounds all wrong for any guitar amp. The place that sold it could have just put in whatever tubes they had handy - so look for a tube chart or some kind of markings and on the bottom of the chassis wouldn't be unusual for a 1960s amp.