dobes
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Post by dobes on Jan 18, 2014 21:48:30 GMT -5
I have installed PRS 57/08 HB pickups in an Epiphone Spotlight guitar, replacing the original Select, Designed by EMG pickups. The guitar has two HB pickups, one volume, one push-pull tone pot and a three way toggle. I made a diagram of the way it was wired with the EMG's and installed the 57/08's the same way. The bridge sounds pretty good, combined sounds pretty good, coil cutting seems to work well, but the neck is very distorted and muddy -really unuseable. I have asked Stew Mac how to wire them and have printed several diagrams, but am unsure of how to interpret them. I found a wiring diagram at Guitar Electronics for this configuration and one for the McCarty, which has this hardware. Why are they different, and of course, the guitar was not wired either of these ways with the EMG's. I suspect that maybe the guitar had been modified to only cut the bridge. Is there a good reason for this? The EMG's had a red (coil cut, I think), a white (hot, I think) and a ground wire. The 57/08's have a hot wire with braided shield and a white coil tap(cut) wire. One diagram shows the hot wires from each pickup going to each side of the toggle. One hot also splits and goes to a prong on the DPDT switch of the tone pot. The McCarty shows one hot going to the toggle and the other hot going to the same DPDT prong and then on to the other side of the toggle. I have the neck hot going to the toggle, but the other side of the toggle has no wire connected. The bridge hot wire goes to the middle prong on one side of the DPDT part of the push-pull tone pot. The coil tap wires go to the top (toward the knob) prongs on either side of the DPDT switch. I think I can figure out how to wire it if I can understand the logic behind the wiring.
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Post by JohnH on Jan 18, 2014 22:37:55 GMT -5
Hi dobes, welcome to GN2.
It would help to see any diagrams that show what you have, and what you have found, and maybe photos too.
Are the pickups active or passive?
John
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dobes
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Post by dobes on Jan 19, 2014 6:11:46 GMT -5
Hi dobes, welcome to GN2. It would help to see any diagrams that show what you have, and what you have found, and maybe photos too. Are the pickups active or passive? John I will draw up what I have and try to get some pictures. Thanks. I guess what I am looking for is advice on the rule or theory of the pickup. In other words, the signal must go from the pickups to the toggle first, then to the tone and/or volume pot and then to the volume pot and then to the jack. Thanks.
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Post by Deleted on Jan 19, 2014 13:13:39 GMT -5
Hi dobes, welcome to GN2. It would help to see any diagrams that show what you have, and what you have found, and maybe photos too. Are the pickups active or passive? John I will draw up what I have and try to get some pictures. Thanks. I guess what I am looking for is advice on the rule or theory of the pickup. In other words, the signal must go from the pickups to the toggle first, then to the tone and/or volume pot and then to the volume pot and then to the jack. Thanks. hello dobes. John asked you a question. Where the old ones active or passive? Is there a battery compartment in the guitar anywhere? Now in terms of plain old guitar electronics, the hot goes to the selector -> vol pot -> tone pot.
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dobes
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Post by dobes on Jan 19, 2014 17:55:51 GMT -5
I will draw up what I have and try to get some pictures. Thanks. I guess what I am looking for is advice on the rule or theory of the pickup. In other words, the signal must go from the pickups to the toggle first, then to the tone and/or volume pot and then to the volume pot and then to the jack. Thanks. hello dobes. John asked you a question. Where the old ones active or passive? Is there a battery compartment in the guitar anywhere? Now in terms of plain old guitar electronics, the hot goes to the selector -> vol pot -> tone pot. The EMG's were passive. The PRS 57/08's are passive pickups. You say hot goes to selector, then vol, then tone. Then jack from tone? Most diagrams show selector to volume to jack, with an occasional side trip to those mysterious DPDT prongs of the tone pot or to one of the three prongs on the tone pot. I know the DPDT prongs serve to ground the coil cut wires, but am not sure which ones to connect the pickup coil cut leads to. Right now I have the coil cut leads connected to the two prongs on each side at the top, closest to the knob of the pot. That seems to work to change both pickups to single coil when the pot is pulled out.
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Post by newey on Jan 20, 2014 0:02:50 GMT -5
dobes-
Hello and Welcome to G-Nutz2!
There's more to it than that. There are several ways to wire for coil cuts, but at the very least, if it was as you say, the middle lugs on the DPDT would need to be grounded to cut the coils.
There are also any number of ways to wire the control pots. Ordinarily, with a single master volume and master tone, the pickup selector switch would be wired to the CW lug of the Vol pot, with the center (the "wiper") going to the output jack tip connection. The tone is then wired off the volume pot.
As JohnH noted, it's really difficult to see what's going on using only verbal descriptions. One picture is worth a thousand words, as the saying goes. So, a diagram of what you have now would be really helpful.
But, from your description, I'm not sure this is indeed a wiring problem. It sounds like everything is working fine, except that you are complaining of a "muddy" and distorted neck pickup sound. Usually, a wiring issue will result in one (or more) things not working at all- you get no sound in one or more positions.
It is possible (but unlikely)that a bad solder joint could lead to the distortion and muddy sound you describe. If so, hitting the solder joints for the neck pickup wires, both hot and ground, with your soldering iron briefly may help. Apart from that, I can't think of how mis-wiring something would lead to what you describe.
But before even trying that, I'd try lowering the neck pickup a bit. Also, were these new pickups? Do you know whether the neck pickup was working properly before you installed it into this guitar?
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dobes
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Post by dobes on Jan 20, 2014 16:34:20 GMT -5
I actually have two of these guitars 1988 Epiphone/Gibson Spotlight. The one I have put the PRS's into is Guitar One in the attached sketch. The other guitar was modified at some time and the bridge PU was replaced with a Dimarzio. As you can see, the wiring of each is quite different. Most of the cases of the pots and switches are grounded to each other, but I left those wires out of my diagrams for simplicity. I also want to replace the stock neck pickup in Guitar Two with an EMG HZ 4A (passive). Comments on the two different wiring schemes would be appreciated. Pickups 001.tif (824.74 KB)
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Post by newey on Jan 20, 2014 16:57:36 GMT -5
The wiring for guitar two looks OK, although as shown, it would appear that the vol control is wired in reverse (i.e., lefty). Only the neck pickup has its coil cut in this scheme.
Guitar one's wiring is all bolluxed up. It cannot possible be working as you say it is, if it is, in fact, wired that way. For starters, the bridge pickup isn't shown on the diagram as being connected to the toggle switch, and thus, isn't connected to output. So, that pickup would not be working at all if it were in fact wired as shown on diagram 2. Since you indicated it was indeed working well after your rewiring, there must be something missing from the diagram.
Also, the push/pull pot isn't connected to anything. You indicated that the coil cuts were both working, but that could not be true if it was indeed wired as per your diagram.
Have you performed a "tap test" with a screwdriver to be sure that you are really getting both coils from both pickups? Something isn't adding up here.
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dobes
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Post by dobes on Jan 20, 2014 17:20:02 GMT -5
You are correct. I drew this up from a sketch I did the way the guitar was when I opened it up. Every diagram I saw had a hot wire to each side of the toggle, so I ran a wire from the bridge hot, which is connected to the mid-height, right side prong of the DPDT switch to the other side of the toggle. That is why the toggle works as it should (verified by tap test). When the push-pull is pulled out, the guitar sounds more chimey and volume is reduced, but tapping seems both coils are producing sound.
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dobes
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Post by dobes on Jan 20, 2014 20:44:24 GMT -5
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Post by newey on Jan 20, 2014 22:41:47 GMT -5
OK, now you're showing the bridge pickup connected to the toggle, and the bridge coil cut shunts to the hot, giving you the bridge coil cut. The neck coil cut, however, isn't doing anything. If you only wanted the bridge coil cut, then you're fine, but I'm assuming you wanted the neck to be coil cut as well, so the left side of the P/P (center lug) needs to be grounded.
Given that both pickups are PRS (and so presumably identical as far as north and south poles), shunting the bridge coil cut to hot, while the neck coil cut is grounded, should give you opposite coils when both pickups are combined in single-coil mode, and thus will be hum-cancelling.
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dobes
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Post by dobes on Jan 21, 2014 8:37:57 GMT -5
Thank you for your comments. I want to be able to understand how the system works, and your comments get me thinking. It is clear to me that if I only had a volume control and the toggle how the signal would go to either side of the toggle, then to the volume control and then to the jack. Introducing the tone control and how it is introduced into the circuit is a mystery to me. In other words, is it in parallel to the volume pot, or should it be in series to the volume pot, and how should the three tone pot lugs be connected to accomplish this? I get that the DPDT switch is totally independent of the tone pot.
I do have a couple of questions about your comments. You say the bridge coil cut shunts to the hot, giving the coil cut. Shouldn't the coil cut be to ground to cut to single coil? I see that the neck coil cut wire goes to the top prong on the left side of the DPDT, but there are no other wires connected to that side, so it is not being shunted to ground and therefore not cut - not doing anything, as you say. I realize that the intention is sometimes to wire a guitar to only cut one of the HB's. Maybe that is what they did here. I would like to start by cutting both and then make changes if I don't like what I hear. By the way, the distortion I described on the neck HB goes away at lower volume knob settings, so the guitar is useable as it is wired, but I would like to explore all of the options.
You commented about shunting the neck pickup to ground, with the bridge pickup shunted to hot as it is now. To do this, it looks like I just have to connect a wire to the middle left DPDT prong and then to ground. Am I correct?
Looking at guitar two, it looks to me like the bridge pickup is soldered to single coil mode, and when the toggle is in bridge only, and the push-pull in or out, the volume is about equal, but pulled the strings seem a a little more distinct and slightly more chimey. It looks to me like the DPDT switch is switching the neck pickup only between HB when pulled out, or to the signal from the coil cut wire (single coil, but wrong coil?) when pushed in. It is possible that I am mistaken on which of the EMG (neck PU) wires is the hot and which is the coil cut lead, so that pushed in is the full HB and pulled it is the signal from the coil cut lead only. This begs the question, what is the difference between using the signal from the coil cut lead only versus the hot lead with the coil cut lead grounded? It seems that the wrong coil is engaged. Is there a difference in the sound? I assume you don't want to use the coil cut signal, unless there is some hum cancelling benefit.
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dobes
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Post by dobes on Jan 23, 2014 19:27:41 GMT -5
I was hoping for some critical comment on my last post, but I think I understand the way the pickups and wiring work now. I have a question about pots. I replaced the original small 500K asian volume pot (I suspect it was linear taper) in the Epiphone with a larger diameter CTS vintage audio taper guitar pot. I would like to replace the tone pot with the attached DPDT switch if there would be an improvement. I see the Alpha and the Bourns version are available. Which is better, and is there something better out there? These pots look like they have have smaller diameter cases like the asian volume pot I got rid of. Also, what size capacitor is recommended? Thanks.
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Post by newey on Jan 23, 2014 23:53:32 GMT -5
dobes-
Sorry, for some reason I didn't catch your post from the 21st.
Let's try to break this down a bit:
Depends upon which coil you want to cut, and which you want to remain operational.
These are three-wire HBs. In a 4-wire HB, you have independent wiring of both coils available. With a 4-wire pickup, there are a couple of different ways to do coil cuts, depending on how you wire the coils.
With three-wire HBs (I am not counting any bare or braided shield wires), you have a "hot", a "ground" and a "coil cut" wire. The coil cut wire is really connected to both coils- to the start of one and the finish of the other. The two coils are connected, in series, internally in the pickup, and the coil cut wire joins to this connection.
So, if the coil cut wire is switched to ground, you get one coil (the other coil is shorted to ground at both ends). If the coil cut is switched to the hot side, you will get the opposite coil (the second coil is shorted to hot at both ends). If the coil cut wire isn't connected to anything, you have the full HB, both coils in series via the internal connection between the coils.
Yes. Just so we're all using the same terminology, the points to which one solders on pots and switches are called "solder lugs", or just "lugs" for short. "Prongs" is going to confuse someone down the road, although I got your meaning.
I don't think you're quite understanding what's happening here. On Guitar two, as shown in the diagram, with the knob pushed in, you'd get the coil cut. With the knob pulled out, you'd get the full HB. If you had mislabeled the wires, showing the "hot" on the diagram in place of the coil cut, the switch would operate the other way around, with the full HB when pushed in.
On Guitar two, the DM HB at the bridge is shown as being only a two-wire (plus the shield), so it cannot be split (unless you break into the innards to rewire it). Thus, in guitar two only the neck HB is split. In that scenario, there is no "right" or "wrong" coil to split. Mostly, we are only concerned with selecting to cut one coil versus the other when there are going to be combinations of coil-split pickups (or, a coil-split HB combined with a single coil). By selecting the right coil in those circumstances, we can make the coil-cut pairs be hum-cancelling.
Most HBs are designed to have their coils be pretty similar to each other- that's what makes for better hum-canceling. WIth two similar coils, it's not going to make much difference sound-wise whether it's the N or S coil that is used. The difference in the coil's position along the string will make for a bit of a different sound, but moreso at the bridge position- the slight difference in coil position is accentuated closer to the end of the string.
With a neck HB, and assuming fairly equal coils, I've never heard much of a difference with which coil is cut.
Some HBs are purposely built with dissimilar coils, and with those, and especially at the bridge position, it may indeed make for a different tone depending on which coil is selected to be cut. There are various wiring schemes which allow either coil of a HB to be selected via a switch.
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dobes
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Post by dobes on Jan 24, 2014 12:00:50 GMT -5
Okay, I don't think any of these pickups are three wire. The PRS's have a Single (hot?) wire in cloth inside a shielded cable. They also have a separate white coil cut lead. The PRS literature that came with them states that this is what they are. Grounding the white wire (through the appropriate lug on the DPDT switch) on one or both HB's grounds one of the coils, producing sound from the other single coil(s). I think I understand how to change it to get single coils when pulled.
You say that the DM is a single conductor so it can't be split. The PRS's have a single hot and a coil cut wire, so it seems the Dimarzio could be similar. The Dimarzio has a white wire, a black wire and a solid, bare wire inside a plastic cable. For simplicity I didn't show it, but the cases of the two pots and the toggle are all grounded together, so the black and bare wire soldered to the toggle case made me wonder if one coil is being shunted to ground, creating a permanent single coil. This grounding of the cases together may also explain how a signal is able to travel between the tone pot and the volume input lug on both guitars. But, I don't understand why the capacitor is placed differently on each guitar. The cap is connected to the output of the tone pot in each guitar, but but runs immediately to ground on Guitar One(PRS's) and runs to the input of the volume pot on Guitar Two. Are the tone pots connected in parallel with the caps bleeding off the high frequencies? Should it be connected in series?
What value of caps are recommended, and do you suggest replacing the asian push pull/tone pots with similar pots by Alpha and/or by Bourns or?
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dobes
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Post by dobes on Jan 24, 2014 12:53:51 GMT -5
I think you are right about the Dmarzio humbucker. By tapping them, it seems both coils work whether the tone is pushed in or pulled out.
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Post by newey on Jan 24, 2014 23:34:25 GMT -5
If that's the case, the shield around the hot wire is actually carrying the signal ground. Using the shield to both carry signal and shield against noise is the way vintage Gibson HBs were done.
In modern pickups, the shield is usually separate from the ground wire. But folk still build them with just the shielded cable (plus the coil cut wire, in your case). It's sort of "faux vintage".
Every thing I said earlier still applies, you just have to make sure the shield gets grounded. Using the backs of the pots to ground things is standard procedure.
Yes, if you are meaning that they are connected in parallel with the volume pot.
No.
The fact that they're Asian-sourced doesn't mean they're junk. There are good mini-sized pots (and bad ones), and not all "full-sized" ones are necessarily good.
Paying the extra money for a better-quality pot doesn't get you better performance (although it may get you tighter manufacturing tolerances). It may get you some added longevity and a better "feel" as you turn the shaft. If I'm refurbishing an older guitar, I usually replace the pots- it's a moving part, they do wear out eventually, and I'm usually figuring I won't be going back in to the wiring anytime soon. I figure might as well upgrade while I'm in there.
But if it's a newer part and it's working fine, I don't ditch it just because it isn't some brand name.
That's a matter of personal taste. And there's a lot of wacky thinking floating out there in the webs . . .
Understand that the cap value makes no difference in the sound of the guitar until you begin to turn the tone control down. As you do begin to turn it down, the cap value affects the frequency curve of the hi-cut filter.
Standard value for HB-equipped guitars is traditionally .047µf. Fender generally uses .022µf for its single coils. I've been using .033µf recently for HBs, I think it's a pretty good compromise value.
As far as the differences in the placement of the cap between the two schemes, the tone control essentially works the same either way. There is a bit of difference but it's subtle at best.
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Post by newey on Jan 24, 2014 23:45:39 GMT -5
I guess I should also mention that the difference between a lower value cap, like the .033 I use instead of a .047, is that the lower value will have a more subtle roll-off of the treble as you turn the tone down. The higher value will have a more dramatic "darkening" effect as you turn down. I think the lower value lets you "fine-tune" it a bit more, but it's a subtle difference at best.
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dobes
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Post by dobes on Jan 25, 2014 7:30:39 GMT -5
Thank you for your help!
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Post by dobes on Apr 21, 2014 21:19:31 GMT -5
I finally rewired my Epiphone Spotlight, into which I had installed PRS 57/08 HB's. I had previously posted about this guitar. I have attached a scan of the new wiring diagram showing also the old diagram, which I posted previously. The old diagram was the way it was factory wired (?) with the original pups. I replaced the original pups with PRS 57/08's. The original wiring did not seem to make sense, and the sound was not loud or good. Each pup has a shielded hot wire and a separate white "coil tap" wire, as PRS calls it. For this rewiring, I used a simple ARTEC diagram for a two HB, one tone, one volume and one three way switch. The diagram was for single conductor HB's. I have the push-pull tone pot and the coil tap wires (which PRS says ground one coil on the pup). I decided to wire the bridge without connecting the coil tap wire to anything. I assume the result would be full HB on that pup - or would it only be one coil? The neck pup, as you can see from my diagram, gets cut to ground when the tone knob is pulled out. If anyone is familiar with PRS pups, am I understanding how the leads work correctly? Am I getting the full HB on the bridge, or should it be jumped to something? Should I install any other jumpers? Thanks for any comments. Spotlight Wiring 4-14 001.tif (823.16 KB)
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Post by newey on Apr 21, 2014 21:53:33 GMT -5
Hey dobes-
Yes. The two coils of the HB are connected internally in series, and the coil cut wire is running off of the junction between the two coils. With the coil cut wire left unconnected, the 2 coils remain connected internally, in series, for the "full HB" sound.
No, assuming you want it to cut the neck to single coil operation and to leave the bridge HB unaffected. If so, you're good to go. The only proviso is that all the points on your diagram which are marked as being to "ground" do all need to be tied together at some point.
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