Balancing P-Rails

[Nigel]

I've used the 1 vol, one tone, 2 push/pull arrangement.

Seems like a 250K and 500k wired modern (tone connected to input of vol, cap from tone wiper to ground) yields best P-90 tone in terms of chugga chugga.

The Humbucking sounds are bit dark there.

Rewired 50's style, the humbucker sounds wide open and balanced, whereas the P-90 looses girth. Woman tone works best this way (.015 cap), but no QOTSA 'bucker tones rolled back. I believe the 50's wiring takes a great deal of load off the pickups, as the tone pot is in parallel with the output. MUCH brighter!

Is everyone pretty much happy with 500k/500k modern style wiring? Seems like additional resistors in line to ground when switching would give us better balance, ala Tom Anderson's innovative "Vintage Voicing," where a 333k resistor goes in when single coil modes are engaged. Thus, they see 142K with two 500K pots.

Anyone done some 3 or 4P/DT switches with this in mind?

It would be appreciated if some Duncan engineers would chime in. I'd say 99% of customers will NOT have an additional resistor network intelligently integrated into their guitar's electronics, so I'd be interested to know what engineering steps were taken to balance the P90/SC tones from the humbucker tones with a 250K net load in mind. Thanks!

 

[Nigel]

Re: Balancing P-Rails

Bump for SD experts! C'mon fellas...you must have observed these angles in the design phase and made decisions.

This guitar (Ibanez ST-100) is somewhat of a "Biter" and requires brass saddles on the B and high E strings. Seeing as the series HB tones need higher resistance to ground, and the P-90's less for best tone and feel, there must be some info!

 

[frankfalbo]

Re: Balancing P-Rails

Well, there are 3 & 4PDT switches out there and that's a pretty easy way to add loading to the coils in certain positions. It's a pretty simple circuit, just use the other poles of the toggle to engage your resisitor to ground.

As for what steps were taken to balance the pickup's modes to a potentiometer load, there were no further steps taken than putting a coil split onto a JB. You work with what you have in the control cavity. If you like 250k pots on humbuckers, then you'll use 250k on the whole guitar. If you like 500k pots on the Humbuckers, the P90's and Rails don't particularly "suffer" from harshness. I guess what I'm saying is, the pickups are designed to be affected by the load of the potentiometer in the same way any other P90, HB, or single coil would be affected. That means someone like yourself, who goes the extra mile to try to balance the coil loading, will be able to enjoy the fruits of your labor. Does that make sense?

In other words, people with 500k pots on their JB's or 59's or whatever don't usually institute loading with their coil cuts. Nor do most people with H/S/S guitars or H/S/H guitars. The P-Rails are no different.

 

[Nigel]

Re: Balancing P-Rails

Thanks Frank!

 

[uOpt]

Re: Balancing P-Rails

You are talking about what's happening when you roll the pots down, right?

I think you need to experiment with various treble bleed mods to fine-tune this. You can probably find one set of values that sounds good for both situations.

 

[Nigel]

Re: Balancing P-Rails

You are talking about what's happening when you roll the pots down, right?

I think you need to experiment with various treble bleed mods to fine-tune this. You can probably find one set of values that sounds good for both situations.

No. It's the total resistive load on the pickups. 50's wiring reduces the load because the hot output is in parallel.

Single coil pickups like to see 250K (strat bridge) or 125K (neck and middle). Humbuckers like 250K and above, which is what two 500K pots gets you. If you 50's wire the tone pot, it's like taking load off and makes things brighter.

So, the humbucker tones want less loading, the SC and P-90 tones want more. You can wire up resistors to engage when you switch modes to create the electrical environment single coils usually get.

 

[Nigel]

Re: Balancing P-Rails

I'd like to see P-Rails wiring for four pots and four switches, so you can independently load each pickup and do series/parallel/SC/P-90 too.

 

[uOpt]

Re: Balancing P-Rails

No. It's the total resistive load on the pickups. 50's wiring reduces the load because the hot output is in parallel.

No, when the pots are at 10 there's no electrical difference in these wiring options.

You can draw a chart and annotate the resistance seen. I think you mentally mix up the issue of what happens when the pot is at 10. The resistance towards the outer post is zero, not pot face value.

So, the humbucker tones want less loading, the SC and P-90 tones want more. You can wire up resistors to engage when you switch modes to create the electrical environment single coils usually get.

Yeah but that screws up the pot curve when you actually use the pot.

 

[Nigel]

Re: Balancing P-Rails

No, when the pots are at 10 there's no electrical difference in these wiring options.

Not in my experience. The 50's wiring is much brighter on any guitar I've done it too. Modern wiring loads the pickups from the switch before the signal goes into the volume pot. 50's wiring loads the hot output in parallel with the output jack. This means the pickups' output are met with two resistive loads in parallel (modern), or they go through one (volume) and then meet the output to the amp and the tone pot (50's).

 

[uOpt]

Re: Balancing P-Rails

Very sorry, but no, it doesn't, not with the pots at 10.

Please post or link the specific wiring diagrams you think sound different and I'll annotate them with the actual load values.

(no free-speech description, please, diagram. I don't want to miss some wired thing you might have put in)

((of course there's a difference when the pots get turned down))

 

[Nigel]

Re: Balancing P-Rails

Very sorry, but no, it doesn't, not with the pots at 10.

Please post or link the specific wiring diagrams you think sound different and I'll annotate them with the actual load values.

(no free-speech description, please, diagram. I don't want to miss some wired thing you might have put in)

((of course there's a difference when the pots get turned down))

The wiring is the same as has been posted by many, modern being tone to the input of the volume, 50's being tone to the output of the volume (middle lug). I'm clear on that.

Perhaps my pots were damaged. It's possible. However, many report that 50's wiring is brighter all the way around. If they are electrically identical, why does one sound brighter than the other? I did have my cap from the center lug to ground when I modern wired my P-Rails. What effect does the capacitor's orientation generate, as modern (SD style) has it from the pot to ground, where vintage has it between the pots?

 

[uOpt]

Re: Balancing P-Rails

The wiring is the same as has been posted by many, modern being tone to the input of the volume, 50's being tone to the output of the volume (middle lug). I'm clear on that.

No, "posted by many" doesn't do it.

"50ties" wiring means different things to different people. At the very least these things all get classified as "50ties wiring" at some point or another:

1) connecting the volume pots backwards (no effect with pots on 10)

2) connecting the tone pot to the slider of the volume pot (no effect with pots on 10)

3) changing the order of capacitor and resistor in the tone pot (no effect at all)

That's why I'm insisting you specifically state which one you did.

Perhaps my pots were damaged. It's possible. However, many report that 50's wiring is brighter all the way around.

I don't think that's accurate. People do the above stuff for a variety of reasonw, but the sound with the pots at "10" doesn't change. You can easily see that by taking a red marker and delete the zero-resistance parts that result from a pot being at 10.

Some people use some of these wirings because they get a nicer behavior when turning pots down.

Some use them because they imagine things.

Some have a wiring screwup or broken pots and have a difference that shouldn't be there.

If they are electrically identical, why does one sound brighter than the other?

They don't.

Did you make recordings so that you can be sure?

I did have my cap from the center lug to ground when I modern wired my P-Rails. What effect does the capacitor's orientation generate, as modern (SD style) has it from the pot to ground, where vintage has it between the pots?

Exchanging the order in which resistor and capacitor in a first-order low pass filter (aka tone pot) are in does nothing.

This isn't what I mean, I wanted precisely your own before and after that you hear a difference with.

Then you can photoshop them and scratch those resistors that become zero ohm when the pot is at 10 and you'll see that the first two parts of the 50ties wiring variants become NIL (the third never did anything).

 

[Nigel]

Re: Balancing P-Rails

That is how I wired them before (seymour) and after (50's), with 250K audio volume and 500k audio tone with an orange drop .015 cap.

I found this over at the Gear Page:

Modern stock Wiring
Pro - Because the tone controls receive their signal from the input of the volume pot, they are effectively connected directly to the pickup. Consequently, the volume pots' positions have no effect on the operation of the tone controls, which operate completely independently of the volume controls.
Con - The tone changes as you roll down the volume pot - there is some treble roll-off in addition to the volume roll-off. This doesn't bother some people at all, while it drives others crazy. In any case it can be compensated for by installing a volume kit, which is a resistor and capacitor wired in parallel across the volume pot's input and output lugs. These are pretty effective, but there is some modest tonal compromise associated with them, they're not a perfect fix. Still, the majority of people who try them find them to be an improvement.
Vintage 50's Wiring
Pro - Whenyou roll off the volume control, you don't have a corresponding treble roll-off, the tone stays consistent.
Con - The tone and volume controls are interactive, because the tone controls receive their signal from the output of the volume pots (rather than the inputs). Because the position of the volume pot affects the tone control, the tone control's effect is inconsistent. As an example, if you like the tone control set at 5 with the volume all the way up, then this may change as soon as you roll the volume pot down some. Bottom line, there are compromises with either wiring style. You'll have to choose which compromises you're more willing to live with.

and

I had a debate on les paul forum about the effects of 50's wiring and the outcome was this as tested by one member on an oscilloscope. Modern wiring actually rolls off high end even with everything full up. The reason for this is the cap attached to the input loads the pickup and sucks off a little high end even with the toine control full up. As you turn down the volume the resistance change from the volume pot sends some more frequency to ground rolling off the high end faster than the rest of the signal. 50's wiring on the other hand allows more highs to pass even with everything full up as the tone cap placed on the output of the pot is not loading the pickup. as you turn down, the high end actually pushes up slightly and the tone overall gets a slight coloration or filtering effect. %0's wiring doesn't work for every se of parts. I wouldn't use it with a high output pickup for example but its great with a low and medium output pickup and in a guitar that is not lacking low end.

Thread:http://www.thegearpage.net/board/showthread.php?t=378547&highlight=50's+wiring

I've got some 250K and 500K pots coming. I'll experiment and post my findings. Methinks 50's wiring is OUT for these bad boys, at least until I do switches and different circuits for neck and bridge. Thanks for the replies, brother!

 

[uOpt]

Re: Balancing P-Rails

First quote is correct.

Second quote, first part is nonsense. There is no sucking off. With the volume pot at 10 it makes no physical difference whether you have the tone pot connected to the slider or the outer post. This is a common misunderstanding with people who think that a 500 Kohm pot has 500 Kohm between slider and the post it is turned towards. That's not the case, it has 0 ohm. The quote goes on correctly mentioning that it does of course make a difference when you turn down the volume pot.

Another misunderstanding in the quotes is that only with certain wiring you will have tone changes from the volume pot. As wired up in a passive guitar the volume pot lowers the amplitude of the resonance peak as you turn it down. There is a sound change just from the volume pot when turning it down, even if you don't use or do not have a tone pot. How much exactly depends on other factors such as the input impedance of the first active element in the rig.