650C FG - HB-1 series/parallel mod

[Burntweenie]

Hello board.

My first post. I've owned a 4003 from new since 2001, and bought a 650C FG this week as I couldn't resist the deal offered.

Stunning guitar, wonderful to play, but a bit muddy, so I've decided to swap out the controls for 500k pots. I'm also fitting a 5-position rotary capacitor selector for the tone circuits, as well as a series/parallel selector for the HB-1s to brighten things up a little. I've also planned a coil tap bleed to the spare tone pot lugs for when the pups are in series (cuts in between 8 and ten on the tone pot).

All this is going on a black 620 style scratchplate.

I'l post some pics when she's finished!

Cheers for Kent, UK!

[ajish4]

Welcome Mark,

Glad you found our little corner of the web!

[kennyhowes]

I'd like to see what you come with!

[Burntweenie]

Well, the mod is now complete. I had to make some changes as control area is on the wee side on a 650 - no room for a rotary switch I'm afraid.

What I ended up with was fairly conventional in the end - parallel wired HB-1s, A500k CTS pots for volume and treble, a 1nf cap wired in series with a 130k resistor across the input and output of each volume pot to reduce treble bleed, and a DPDT switch offering .022uf or .0068uf for the tone circuit. I might swap out the .0068uf for a .0047uf but I'm not decided yet. The black scratchplate and Rickenbaker 'white line' knobs made the final cut.

The result is lots of brightness and definition all round. Things really come to life when running through a compressor (a modded CS-3). I may get an old Dyna compa and mod it to save forking out on a Jangle-Box as my next project.

For the record, I'm running through a Deacy amp and from there into Logic. Will have a look at what's what output wise through a spectrum analyzer at some point.

Cheers!

[Burntweenie]

Hmm, been playing around in more detail and I have a few issuses/observations.

Volume - no volume 0-2, very subtle volume increase 3-7, hot/dramatic increase 8-10
Tone - dramatic sweep 0-3, very subtle change 4-10

Any ideas why this might be happen would be greatly appreciated - all wiring has been double checked and everything is as it it should be i.e. a 'clone' of the orignal 650 schematic.

Hmm indeed...

[aceonbass]

A good pic of the wiring would help, but I'd bet it has something to do with the extra tone caps you have in there. Also, a .0068 tone cap will KILL the bass on a pickup, while a .0047 cap wouldn't be much better.