Pickup Tone Multiplier

[Von Felgenhauer]

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Anyone ever see this? All bass. No Treble just posted this on facebook. It looks like a fun kit, but, what does it honestly do?

 

[bongomania]

All it does is turn each pickup on and off; flips the phase of one of them (for a thin nasal tone); and lines them up in either series or parallel.

People have been doing this sort of switching since 1960 if not sooner, so the idea that their product is "revolutionary" is utterly bogus. I also highly doubt they actually got a patent on it. The rest of the hype makes me think they're probably lying about that.

"100% more tones" is also nonsense. If you were only able to switch your two pickups on and off, with no blending, then it would make sense: four is 100% more than two, and adding the phase flip and series/parallel gives you two more sounds. But since nearly all two-pickup basses allow blending, then that is a nearly infinite array of tones that you lose with their switching system. Infinity is much larger than two, so they lose.

 

[Von Felgenhauer]

Kinda was thinking it was snake oil.

 

[SGD Lutherie]

I really doubt this is patented!

They say:

It provides you with 3 switches. Two of them turn each of your 2-pickups on and off (both in normal phase and reverse phase) and the third switch puts your two pickups into either a series or parallel circuit configuration.

I was doing that on my basses and guitars since 1972! All they did was make a circuit board to do the wiring.

If you look here:

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You can find the color codes for various pickups. On those color code pages it shows how to wire up switches for phase reversal and series parallel. That's all you need. With the series parallel, just wire up the two pickups instead of the two coils of one pickup.

I bet Line6Man has all these circuits drawn out.

One thing about this is, you don't need two phase switches. You only need one. If you put both pickups out of phase, they are back in phase. Putting bass pickups out of phase on a bass isn't real interesting. It gives you a real thin tone with not too much low end. Series out of phase is a little thicker sounding, but still pretty thin. Listen to the Devo song "Jaco Homo" to hear a Gibson Ripper with the pickups series-out-of-phase.

I have a few circuits I did back in the 80s using two mini switches. One gives you either pickup, or both in and out of phase, and the other does either pickup, or both in series or parallel. So with two switches you get four sounds.

I can post them if you want.

 

[darkstorm]

Imo you'll get much more useful tonal switching by simply adding series/parrellel or coil tap for each pup and phase switch. Only use I can think of for phase switch is perhaps the occassional screaching ted nugent type thing done on bass. But I had better voice imo doing that with gibson thunderbird bass back in the 70's. And useing speaker cab for controlled feedback tones. Favoring bridge pup some. lol.

 

[Orangeclawhammr]

This company had a booth at a guitar show in suburban Detroit this weekend. I tried a Jazz Bass with a six toggle switches. Several combinations of the switches turned off the sound completely. From reading all of your posts, I'm glad I kept my money. REALLY glad.

A friend of mine wired a Jazz Bass for series/parallel. That added an interesting choice of sounds. However, I've only seen him use that bass twice. His main player is his fretless P-bass with stock wiring.

Go figure.

 

[walterw]

This company had a booth at a guitar show in suburban Detroit this weekend. I tried a Jazz Bass with a six toggle switches. Several combinations of the switches turned off the sound completely. From reading all of your posts, I'm glad I kept my money. REALLY glad.

which is exactly how i always describe these goofy switching schemes: "a few good sounds, a bunch of bad sounds, a bunch of sounds you can't tell apart, and the occasional 'surprise off switch'."

 

[line6man]

It took me 30 seconds to develop a mental picture of exactly how this thing is wired up. It's three switches that they've made a PCB for, to save you the trouble of wiring it up with short lengths of wire. This is nothing special, and certainly not something I'd think would be patentable.

If you want to do it yourself, you just need two DPDT On/On switches and a DPDT On/On/On.

 

[line6man]

This company had a booth at a guitar show in suburban Detroit this weekend. I tried a Jazz Bass with a six toggle switches. Several combinations of the switches turned off the sound completely.

Was it when the series/parallel switch was set to series, and the pickup selector was set to solo one of the pickups?
There is a way around that with an alternate wiring scheme on the series/parallel switch.

 

[Stealth]

Line6man: That'd be one where the Vol pots are parallel to the pickups, right?

 

[Orangeclawhammr]

Was it when the series/parallel switch was set to series, and the pickup selector was set to solo one of the pickups?
There is a way around that with an alternate wiring scheme on the series/parallel switch.

To be honest, with you, I had no idea. Something to allow the pickups in series might be interesting, but I get lots of variety from the VVT controls on my SS Jag. LIke I said, I'm glad I hung onto my money. I'm just more convinced of that after reading your posts.

 

[Stealth]

OCH, I just remembered - that's the last wiring I did on a friend's J-bass.

The wiring schematic is ugly as hell, but it works, and you get a lot of blend options between the two.

Line6man, since the pickups are effectively in parallel with the pickups, which taper would give the smoothest transition (like the one we're used to on a common Jazz bass) - lin, log or revlog?

 

[line6man]

OCH, I just remembered - that's the last wiring I did on a friend's J-bass.

The wiring schematic is ugly as hell, but it works, and you get a lot of blend options between the two.

Line6man, since the pickups are effectively in parallel with the pickups, which taper would give the smoothest transition (like the one we're used to on a common Jazz bass) - lin, log or revlog?

That diagram does not make much sense.
The switch, assuming a standard DPDT pin layout, does nothing.

 

[khutch]

That diagram does not make much sense.
The switch, assuming a standard DPDT pin layout, does nothing.

I could be wrong but I think the numbered points on the switch lugs and pot lugs are supposed to be connected together. That will make the switch do something, I have not drawn out the full schematic to see what it does but then I would further suppose that the right half of the schematic shows what it does.

Ken

 

[Stealth]

Yes, the numbers and points go together. That's why I said the schematic is a mess and needs a redraw. I have it on paper but haven't had time to digitize it using Dia. 'm working on it right now (suspended till Wednesday)

I found it in one of the threads on TB, tried to wire it, failed, had it checked at Link Removed only to find the schematic is valid and commonplace eyebrow Wiring it a second time made it work after I found a short on the neck pot.

 

[Stealth]

New post time, because this is relevant enough for a bump. Click to view.

Additionally, I did a crude calculation to see how the real output impedance of the pickup varied with the volume sweep (disregarding inductance and capacitance for simplicity's sake) and came up with the graph on that link. I assumed a Jazz bass pickup with 9 kOhm DCR (bit on the hot side) and its respective volume pot with 500 kOhm resistance. I'd say that graph is reason enough to use a log pot for a volume to balance out the sweep.

On a related note, isn't the term "log pot" a bit of a misnomer since the taper is decidedly... exponential?

 

[walterw]

Additionally, I did a crude calculation to see how the real output impedance of the pickup varied with the volume sweep (disregarding inductance and capacitance for simplicity's sake) and came up with the graph on that link.

I'd say that graph is reason enough to use a log pot for a volume to balance out the sweep.

you just knew i'd respond to that one!

sure, the plot shows the curve doing an "anti-log" sort of bulge, but in actual practice on actual instruments the linear volume behaves evenly with typical clean bass tones. (maybe inductance and capacitance can't be disregarded here?)

fire up the overdrive and heavy compression and the sound does behave like that graph with linear volumes, which is why i recommend audio volumes for guitar players.

On a related note, isn't the term "log pot" a bit of a misnomer since the taper is decidedly... exponential?

is "logarithmic" not an exponential effect? (my math is a bit fuzzy on this point)

 

[SGD Lutherie]

On a related note, isn't the term "log pot" a bit of a misnomer since the taper is decidedly... exponential?

Well it is a logarithm.

The idea of logarithms is to reverse the operation of exponentiation

So the curves do look very similar.

 

[Stealth]

walterw, SGD - I admit, I was kind of baiting there. But in all honesty, the first thing that comes to my mind when saying "logarithm" is the logarithmic curve, not the exponential curve - I do realize that being inverses of each other they are two sides of the same coin. You could be right - maybe the effects of the inductance and capacitance can't be disregarded here. I'll edit the schematic in the evening to reflect the "lin vol/log tone" taper selection.

line6man - can you verify the schematic? I swear it works! I have Invalid Link Removed to prove it.
Kiwi Requiem - The Decision, fingerstyle
- neck, bridge, parallel, series
Kajagoogoo - Too Shy, slapping
- parallel, series, moderate compression
Cream - Sunshine of Your Love, fingerstyle
- parallel at full tone, half tone, zero tone, then series at full tone, half tone, zero tone
Siouxsie and the Banshees - Israel, pickstyle
- parallel, series

 

[khutch]

On a related note, isn't the term "log pot" a bit of a misnomer since the taper is decidedly... exponential?

The term comes from the fact that human hearing was believed to be logarithmic. So the name got applied to the resistance curve even though, as you say, it is an antilog curve that is needed and is used in "log" pots. As it turns out human hearing is power law anyway but all the pot curves (even linear apparently) are close enough to please most people.

Curiously, the most common audio (and if we use that term we avoid the mathematical inconsistency) taper pot seems to be too extreme to be a good match to human hearing. They are a bit worse than linear pots actually. Plus, there are few, if any, truly audio curve pots on the market. Almost all have a bilinear curve that is only a crude approximation of the desired curve. Even so the common audio taper pot does give a sensibly linear response for perceived volume versus shaft position. I know that many here feel they do not but the problem appears to be that all pots have such a large dynamic range that below a certain point any pot appears to do nothing. Audio pots put that point higher up on the rotation curve than linear pots do. If you crank the gain up on your amp so that you can hear the sound again at that point and continue to turn an audio taper pot down you will discover that the audio pot is indeed reasonably linear at low volume levels. Linear pots give a reasonably linear volume/rotation response at high volumes and the point at which they "do nothing" is so low that most people aren't bothered by it. Truth be told, most people aren't bothered by audio pots either, though there are notable exceptions.

So why, I have to wonder, has the audio industry settled on an audio taper curve that seems unsuitable? I can only speculate but it seems to me that stereos are used in one of two situations: at home alone listening to quiet music (well some of us do anyway), or at home with a party raging and the music cranked. The "wrong" curve gives you a volume control with a reasonably broad rotation range over which either situation can be handled gracefully. A linear curve may be more suited to situations where only high volumes are used. The correct audio taper would be best if you regularly need to work at intermediate volume levels too.

The common audio taper pot reaches 10% resistance at 50% shaft rotation. The optimum taper reaches ~30% resistance at 50% rotation. Link Removed Invalid Link Removed I endorse neither vendor, they just turn up in a web search for "30% audio taper guitar pots". I have not tried to figure out what taper my bass uses either since I am perfectly happy with whatever it is. In principle it is not terribly hard to do, just set the pot to 50% rotation and measure the resistance from the center lug to the two outer lugs. In a linear pot the two readings will be roughly equal, a 10% audio pot will measure roughly 10% of the total resistance on one side and 90% on the other, and a 30% pot will be roughly 30/70%. In practice loading from other circuit components in your bass can corrupt the measurements unless you desolder two of the pot lugs to isolate it. I am particularly loath to do that because my volume pot is soldered into a preamp circuit board!

Ken