JohnH

I think it needs to be done as i noted, to get the two halves of the switch working together to do series/parallel. You can see there are two S3 lugs joined together. These need to end up diagonaly opposite rather than on the same side. since they dont get connected to at the same time. Also, if you are doing S3 as a push/pull, then the lower side on the diagram needs to be the side mounted to the pot. Thst so you get the more normal parallel option with the switch pushed in, and then pull out for series. good luck John

I think the diagram is generally very good, and the all-off connection to ground is right. It shorts the output, only if both are off. Theres one problem on S3. All the wires currently shown on the top left lug should be moved to the lower left lug, and vice-versa. If you fx that and repost, Ill look at it again It may be hard to get the coil phasing right first time in terms of the + and - on each coil - but give it a try! If you want to figure this bit out first however, you can do this with an analogue multi-meter. Do you have one of those? If so Ill explain, otherwise its best guess. John

Seems to be OK. Im assuming its a special blend pot made for the purpose with one track that goes 0k, 500k in centre, 500k, while the other goes 500k, 500k, 0k There's a risk that the blend pot may need its hot and ground output wires swapped - depending on which side of which track is which. You could probably find a diagram for it. Or just try it - if its wrong, youd get zero output in the centre instead of both on full volume. The kill switch, if it is like an LP toogle, will be off in two positions and on in one. good luck John

OK, take a look at this: Ive done the coil cut and phase switches so when you operate both, you always get the optimum coil for hum cancelling in combination with the neck Sc. It also gives you access to both Hb coils if you just select the bridge pup ie changing phase also changes which Hb coil is selected. Good luck, I think it should work out great, provided you can figure out the Hb wire colours etc. Ive done other versions using these principles and youll get an awesome range of tones. cheers John

Yes I think that is possible. So youd have an on/off toggle for each, which would each be DPDT, and a push/pull pot on say the tone control(?) (or volume control - which do you think would be better?). With both off, the guitar is dead, but if one or both are on, then pulling the push/pull will engage both pups in series mode. How would that be? I can sketch a diagram in a day or so if you would like - it would be quite a good design I think If you can run to a second p/p pot, you can also have a phase switch - then youd have almst everything. how about that? For the diagram, can you interpret a schematic and turn it into a wiring diagram? (your diagram is a wiring diagram)- a schematic is much easier for me to draw. John

It'll work fine, but theres a few extra tricks you may like to consider: When you have both pups on, and the HB is coil-cut, depending which coil is cut you may or may not get a hum-cancelling combo. Thats worth having, so if when you first try it, you dont get hum cancelling in that setting, just swap the hb wires to cut the other coil instead. lets say you had a Seymour Duncan pup (or one with the same wire colours). The usual wiring would be black to hot, red/white joined and green to ground. Try that first, but if you dont get a hum reduction combining eth Hb single coil with the Sc, then change to red hot, black/green joined, white to ground. One thing you might get when you first try it is an out of phase thin sounding combo - unlikely but if you do, it can also be fixed by swapping wires. Park that one for now. The second trick is that you have an 'all off' setting in which neither pup is connected to hot. That will work OK, but you may find it picks up noise. A quieter all off is where the hot is actually shorted to ground. You can arrange for that if you buy two-pole toggle switches instead of single pole. almost the same price. To start with, just wire up one half as you have shown, and the quiet kill switch setting can be wired once its all working. However, if the all-off is not something that you really wanted, how about wiring it so that you get a different sound as a fourth option? If you get the two-pole toggles, you could, as a second stage, wire it up to give you a super-powerful series connection between both pups, so youd get bridge, neck, both in parallel and both in series, all with sc or Hb options on the Hb pup - 7 very good sounds. Bottom line is - your design works - with a few watch-its, and if you get two-pole toggles (ie DPDT) you have some interesting options for further enhancement with no extra parts. John

I am infact using the reverse wired vol for two independant volumes...is that the cause? if so will sheilding make it better? i checked my grounds w/ the meter, they all check out fine. Shielding will help. And I think the reverse wiring is contributing, since the output gets to be quite high impedance, allowing it to pick up noise, raher than being grounded at low volume as with normal wiring Im not a fan of reverse wiring for other reasons also, I think it messes up the action of the volume control and loses tone at lower volume. But do you like the results? I know some people do. I have my LP with normal wiring, and by the time one volume is reduced enough to affect the other pup, it has faded audibly from the mix abd sio that interactive zone I do not find to be a problem. good luck John

No, it's not normal. Your volume pot is missing a good ground connection. Stop worrying about ground loops. Check your volume pot wiring and insure there is a non-interrupted path from the lug on the volume pot to the ground lug on the input jack. If you bent the volume pot lug that is grounded to make contact with the case of the pot, make sure there is a good physical connection and you are not just relying on solder to bridge the connection for you. If you can put an ohm meter on the middle lug of the volume pot with the volume turned "off" and the other meter lead to the ground lug of the input jack, you should read ZERO ohms. If you read anything else, you need to find where it is located and correct it. I agree with the above. A normally wired guitar should be dead quiet at zero volume, even with no shielding. Either, you have no vol pot ground connection, or, are you using a reverse wired volume pot system? (eg, two independent volume controls, wired backwards to avoid one cutting out the other) - If so, although they are often suggested, it could explain the problem. John

Heres what I think: With 250k pots, youll get the same basic volume as a 500k, im terms of the power of the fundamental note, but with a bit less high-end 'edge'. Also, if you have a single 250k volume pot per pup and no tone pot, that will sound virtually the same at full volume as a 500k volume and a 500k tone, when both are at 10. Ive tested thes myself, both practically and theoretically using a simulatiopn program. I had some 300k pots in my LP, and Im changing them to 500k beacuse I like brighter. In the meantime, Ive done a 'no-load' modification on the tone pots, so as they approach 10 they go to infimity, taking load off the pups making them a stage brighter. This works very well and gives me a very full range of tones. cheers John

A useful check is to set a multimeter to resistance, and measure the resistance across a guitar cord plgged into the output jack, at all three switch settings at full volume. If its OK, you should read just less than the resistance of the pups at positions 1 and 3, and half that in position 2. eg, say 6k and 3k, for 6k pups J

It does. But Id also suggest moving the wire that goes from tone to volume, to connect to the left volume pot lug instead of the centre one. That is the usual way and it gives more consistent tone control as volume is varied. John

The trouble is, I cant see how that switch works, and which lugs are assumed to be the poles J

With the designs I posted, the volume and tone pots continue to operate independently on their respective pups, when in series mode. So you couls have eg , a neck Hb with treble fully reduced, at half volume, added in series to a full bridge single or HB, with max treble and volume. John

That diagram seems weird to me. I cant see how it makes the series link between the two neck coils in neck-only mode How about you just make a temporary joint between the two labelled black and white on the neck, just to check that the Hb works? John

The thick white (which I reckon looks pale grey), how many cables go through it? is it a red, a white, plus the bare? If so, then I reckon the red (ie red2) is connecting to the link between coils (which is red1). If, in the control cavity, you already have bare, red and white, then you can already do fullHb or coil tap. Full Hb will be by connecting bare to ground, and white to hot. For a coil tap, keep those same connections and use a switch to short red to ground. Does that seem consistent with current wiring? But if you want the whole 4-conductor thing, with parallel, phase etc (and I think its good to have them!) then either seperate red 1 from red 2 (they are probably joined somewheer under the insulation for the upper , adjustable coil), or, a bit safer, just cut red 1 and connect the end going to the lower coil to a new conductor, which, together with the black, will be for the slug coil. So in summary, you would have: Slug coil - black and lower end of red1 adjustable coil, red 2 and white bare, going to base only, not to coils John

Yes and yes. But if you get a 4 conductor cable, the bare wire will be replaced by all the fine copper bare wires that surround the 4 insulated wires. You twist them together and solder to base of pup, and t ground at the control cavity. That screen or shield is then protecting the 4 main wires from noise, but is not involved in carrying the signal. John

Will you be replacing the existing grey wire with a 4-conductor one? that is the best thing to do. You need a length of cable with 4 internal wires and the screen. The screen goes to the pickup base, and the 4 wires go one each to each coil end. The coils should not go directly to the base (as one of them does now), otherwise, it will mess up when you do reverse phase options. You should start with the old grey wire disconnected and removed, and the two wires from each coil exposed. You should be able to seperate the coils, becasue they were made seperately and then two ends soldered together, maybe tucked inside the insulation. Just be very careful as you tease it apart. this is a good page about the principles: http://www.1728.com/guitar1a.htm Heres my write up on some that I did: http://au.geocities.com/guitarcircuits/fou...rconductor.html I attached a piece of board to the back as a tag strip to fix my cables to. More recently I did a couple of Gibson Hbs, and just soldered the ends of my 4 conductors to the wires from the coils, insulating with some heat-shrink sleeve. John

Regarding heaviness - most JP schemes have a switch to put both pups in series with each other. Thats does get heavy indeed! Without going overboard, a great way to use that feature is to have full bridge Hb, with extra bass from the neck in series. However, most JP designs do not have properly independent volume and tone controls for each pickup, which operate in series mode. It can be done however, such as on these designs at GN2: http://guitarnuts2.proboards45.com/index.c...read=1169255966 With this, you can for example, keep full treble from the bridge, and roll off all the treble from the neck, then use the neck volume to bring up just a selected amout of pure bass to enhance the bridge Hb This one is further enhanced with two extra switches to get inner/outer coils selected and parallel.single,series selection of each pup: http://guitarnuts2.proboards45.com/index.c...read=1181507361 John

Interesting work. If youd like to compare against another expanded JP mod, you may be interested to check this out. Fully designed built and tested twice. It does single, series, parallel, phasing, sytem series/parallel, inner/outer coil selection, always with optimum hum cancelling and intuitive controls! http://guitarnuts2.proboards45.com/index.c...read=1181507361 John

I think bare wire is not a problem unless it is touching something it shouldnt, or flopping about so it might do. A bare wire linking several lugs on te same switch seems fine to me, and you can inspect to see a good air gap to anything else. A problem with trying to insulte that is that the insulation may hide a multitude of sins, and cover a short circuit, perhaps where heat from soldering has melted it. John

250k or 500k will be fine, but Id vote for 250k. People use 500k with series Hb's because it puts less load on these higher impedance pickups, which causes less loss of high treble when at full volume. The down side is that at reduced volume, the guitar is more vulnerable to treble loss due to cable capacitance. But with you parallel wiring, your pup impedance is 1/4 of a series version, hence it can drive 250k pots with little loss, and these will then perform better at low volume. I think tha 250k on the tone pots will, in this case, also give you a more consistent sweep of tonal change, wheres 500k will be more concentrated to the end of the range of tone pot turn. John

Actually, you can do it with a DPDT, in a neat way. take a look at this design of mine, which is a version of a Jimmy Page. ignore everything except switch S2 http://guitarnuts2.proboards45.com/index.c...read=1169255966 John

Further to the above: Heres a great article on the electrical characteristics of pickups: http://buildyourguitar.com/resources/lemme/ see also the table which is linked half way down, with values for a wide range of pups. John

Hi Erik and Unk - heres an example of a pSpice sim where we were checking out an idea for a bass cut tone control: http://guitarnuts2.proboards45.com/index.c...8913&page=2 THe pSpice is near the bottom of the page The pickup is represented as an AC source, which you set to sweep through the audio frequencies. Thats in series with an inductor and resistor, with a 0.2n cap to represent the pup coil capacitiance. Good values for single coils are 2.5H and 6k, and double that for Hbs. Then you model the guitar volume and tone controls as designed, and add the cable capacitance and amp input impedance. Cables are about 40pF per foot, so 0.8 to 1nf cable capacaitiance will model a 2'0 to 25' cable. Amp impedance is often about 1M. I hope that helps. Call in to GN2 to find more of these. John

For an SS amp, Ive seen a few combo designs where the speaker is not directly grounded, but connected via another component such as a small resistor . Without knowing, I wouldnt take a risk. And if as Unk suggested, it might be a pair of push/pull output stages, grief could occur. I added a output jack to my 10W Marshall practice amp, and when I tested across the speaker leads I found that the grounded-est wire to th espeaker still had a resistance to ground - So I used an insulated jack. in fact, it was a switched jack so that I can push a plug in to disconnect the internal speaker, and without any momentary shorts. John