Rickresource Rickenbacker Forum

Hi Guys

Just need a little help, I was playing my 660/12 the other day, doing that Pete Townshend trick of switching quickly between the bridge pickup (down) and both pickups (centre) on the toggle switch to get tremolo kind of sound. I only did it a few times and with no force at all and all of a sudden there was no difference in sound between the down (bridge) and centre (both) positions.

It now sounds like the neck pickup can ONLY be heard when the toggle switch is in the up position, there is no difference between the sound when the toggle switch is down or centre EXCEPT when i use the blend knob. If I turn the blend knob up fully I can hear the contrast when switching between down position and centre but not if its off. Hope I've managed to explain myself and the problem properly. So, basically, how do I fix it?

That's not a problem, that's just physics. With the blend knob or volume pot attenuating the neck pickup slightly, you will not hear the comb filtering that happens between the two pickups when neither is attenuated. Turn both pickups full blast and you will hear a difference in all three positions, but if one is attenuated the middle position will sound like the dominant pickup and will have small elements of sound from the other that aren't easy to detect for some people. But when you are recording sometimes these small contributions matter a great deal and are fun to play with, or some people also like the comb filtering sound when both are full-on.

Comb? I know how the 5th knob works, but never heard it described as a comb

Stuart, please check the little blend knobs as Joshua suggests. Turn both volume knobs open fully. Put the selector switch in the middle position. If you turn the blend knob all the way one side you'll be selecting almost only one pick-up, turn it the other way and you'll be going from almost only one pick-up to a mix of 50-50 in the middle, and turning further all the other way, towards a blend of mostly the other pick-up.

Wildberry wrote:Comb? I know how the 5th knob works, but never heard it described as a comb

http://en.wikipedia.org/wiki/Comb_filter

Thanks for all the advice guys, I swear I had the blend knob completely off when I toggled between the pickups and there still used to be quite a distinctive difference between the down and middle positions. It just seemed to stop all of a sudden due to what I thought was excessive wear on the toggle switch. So what you are saying is that with the blend knob off there should be no sonic difference between the down and middle postions?

RicukStu wrote:Thanks for all the advice guys, I swear I had the blend knob completely off when I toggled between the pickups and there still used to be quite a distinctive difference between the down and middle positions. It just seemed to stop all of a sudden due to what I thought was excessive wear on the toggle switch. So what you are saying is that with the blend knob off there should be no sonic difference between the down and middle postions?

You can't turn the blend knob off, but if you turn it so it is in the center of its turning range. Then it will be "neutralized" and have very little effect on whichever pickup setting you select with the three-way switch.

There is also some good info on settings and the use of the blend knob in the "Owner's Manual," available on the RIC website if you don't have your hard copy: http://www.rickenbacker.com/pdfs/manual.pdf

awww, stu....you broke it. i'll take it off your hands and i won't even charge you a fee !

cassius987 wrote:

Wildberry wrote:Comb? I know how the 5th knob works, but never heard it described as a comb

http://en.wikipedia.org/wiki/Comb_filter

Does the blend knob cause a delay? I doubt it...

Usually when I hand people my Ric, the first thing they do, is turn the blend knob to what they think is all the way open...

Wildberry wrote:Does the blend knob cause a delay? I doubt it...

The blend knob is not special. It's a volume pot. Any volume pot can attenuate the signal from a pickup.

This is probably not the right way to put it but it's the best way I can explain to you a very real phenomenon: the pickups are in a sort of "spatial delay" with each other because of their placement on the guitar body--they see the strings slightly out of phase with one another as a result. When you combine those signals, unattenuated, you get comb filtering and the sound loses some of its midrange. If you attenuate a pickup with a volume pot (blend knob or "true" volume pot, obviously they are both doing the same thing) you will hear this phenomenon disappear in real time. That's what's going on with the OP as well.

The other fact to emerge from this is why the 0.0047 cap is part of the "Ric sound", and that's because it stops comb filtering from happening by putting the signals in perpendicular phases that can't interact. Without the cap, or on most any conventional two-pickup guitar, the pickups are in parallel phases.

Smarter people than me will tell you the same thing, but probably more eloquently.

Sorry, but I'm putting on my full-length wader boots.

mr. hall is either feeling he's deep in it or...he's gonna go visit the gibson factory to look for a brand name canoe !

Try this fellas. Plug into a decent amp--i.e. the input impedance is high enough to get a quality signal for your bass or guitar--and set the pickup switch to the middle position with both volume and both tone controls fully "on", "dimed", "10" "11", whatever. Listen to the instrument's tone. Then turn down EITHER pickup just a bit--to "9" for instance. You'll hear an increase in volume and mids. That change in tone is the cessation of the audible effects of comb filtering because the signals are no longer competing at an equal level. Anybody should be able to hear this effect with ease through a good amp. Then try this with the 0.0047 cap as well if you have the switching pot installed; you'll hear a very similar phenomenon, thanks in part to the fact that the pickups aren't interfering with each other after the signal of one of the pickups is altered in phase 90 degrees above the cap's hinge frequency.

Getting back to the original question Should I be able to hear a difference in sound when I switch between the down and middle positions when the blend knob is turned to its minimum setting? I'm sure I used to get 3 different tones in each of the 3 toggle switch positions with the blend knob turned fully down, now I only seem to be getting the bridge pick up on both down and middle positions, there is no difference.

Stuart, if you are turning the neck pickup down even a little with either the neck volume pot or the blend pot, the middle position will sound less distinct from the bridge pickup than if the pots were not attenuating the neck pickup signal. With the blend pot all the way "down" this will be especially true. There may be some minor difference in tone but nothing like with the pots turned full up.

Folks, we need to start over from scratch. First of all, put the selector switch in the middle. Turn the tone knobs completely up and the volume knobs, including the 5th knob to zero. Then turn the bridge volume knob up all the way. You should get standard bridge pickup full on. Then turn the bridge volume all the way down and turn the neck volume and the 5th knob all the way up. Of course this involves turning the 5th knob "backwards." You should get full neck pickup on.

If this works, we're ready to go on to the next step. If not, it's time to remove the scratch/control plate and see what's wrong.

OK, assuming this all works, and both pickups are full on, there should be some tonal difference between the bridge pickup alone and the middle position both together. Now, if you have a 24 fret guitar, it won't be quite as noticable as with a 21 fret guitar, because the neck pickup, being farther upstream on a 21 fret guitar, will be more bassy sounding. Be that as it may, if you have a 24 fret guitar, you can get a little more contrast by rolling off the neck pickup tone a little bit, say down to @ 7.

Yes, with a 24 fret guitar, the pickups are closer together, so instead of adding a big low end to get a bridge-both "ee-oh" contrast, you will get more of a "ee-ah" contrast, with a little more whang in the midrange if they're both turned all the way up. Part of this is due to the 24 fret neck pickup getting less fundamental, and part of it is the comb filtering talked about above. Strings vibrate in pieces as well as the whole, and the difference in placement of the pickups mean that for some overtones of certain notes on certain frets, the string will be vibrating one way over the bridge pickup and the opposite or near opposite over the neck pickup. For that particular note or group of notes it will sound like the guitar pickups are out of phase and get a little thin sounding, so on certain notes you won't get the "ee-oh" contrast, or even the "ee-ah" contrast, but it will go the other way and get an "ee-ih" contrast. Again, not on everything, just on certain notes.

Then again, Townsend made enough money to use his Rick like that and make money doing it. Serious money. Enough to purchase more Ricks. As for the rest of us mere mortals, and I do include myself in that statement, why risk permanent damage to the selector switch, or even the rest of the guitar or electronics? Then again, maybe I'm just getting conservative in my old age, as I'd hate to have to replace anything about any of my instruments, due to rising costs of parts as well as instruments.