The 5th Knob ...what does it do?

[markthemd]

I thought that as a public service I would post a specific column to answer this often asked question.

If you want the official answer ,ask the staff at Rickenbacker,otherwise this is strictly my version.

When the 1950's were in full swing and STEREO was a new thing ,(as was rock'n'roll,TV,Elvis,etc.)everyone had to be trendy and come up with something that was different.
Gretsch had the 'Project-o-Sound' guitar,
Gibson had the ES-345 and ES-355 Stereo guitars,

But Rickenbacker out did them and gave the option for either Stereo (Rick-O-Sound) or mono (Standard).

Since that time almost every maker has stuck with mono .Rickenbacker still offers the option on many of their instruments.
At the timer there was NO bi-amping of bass gear(there was hardly any bass gear that was electric!)and this was a one up on the competition.

The original guitars came with Flat wound strings,to give a clearer sound a .0047mfd capacitor was installed in line to shunt some of the bass from the bridge pickup .In mono there was a noticeably drop in volume from the bridge pickup compared to the neck pickup.To compensate for this ,a 5TH knob was added.This control could preset the neck pickup volume to balance with the bridge pickup in mono/standard.While at the same time allow you to have a volume control that still performed the standard function.

(Check out the Fender Jazzmaster/Jaguar guitars for a mono variation on this theme.)

This control also acted as sort of a balance control when using the stereo /Rick-O-Sound mode.

The reality is ....this is nothing more than a backwards neck pickup volume control.
On guitars that are 100% mono/Standard,it is a redundant control ,but it has come into transformation on many a repairmans bench.

I turn it into a variable "Rick-O-Tone" control.
That is ,I install the .0047mfd cap on the pot and allow the pot to vary how much low end you want to filter out .This gives you the full volume of "Modern" Ricks or the extra crisp sound of the "Vintage" Ricks.

Why is this control on a mono guitar....?

Ask Rickenbacker ...I have theories ,but so do a lot of other folks and it really does not matter.

I hope this helps answer the question.