Oz_Greg wrote:
I can't recall what "Coil-tapped" means, but I did solder the black/clear to earth along with the others.
The push-pull treble knob works perfectly.
I can definately hear the change in sound in each position.
"Out" is thinner sounding and "in" is much fatter.
Greg
Greg - a quick summary (and I apologise if I appear to be teaching my grandma to suck eggs!):
The HB1 has 2 coils: One coil has black and red wires attached, the other has clear and blue attached. The normal (and best) sound for an HB1 is in series, ie when the output from one coil goes to the input of the next coil. So for our situation, consider the signal flow, staring from the bottom as follows. Red wire at earth/ground, and the signal builds up around the first coil, and out through the black wire - so far at 7.5 KOhm. Black wire is attached to the clear wire, so signal continues its journey, through the clear wire into the second coil.The signal exits second coil, having gained additional oomph and now at 15K Ohm, via the blue wire, towards the switch/pots/jack socket. All these wires are covered with the shield, to further protect from additional interference etc.
In normal use, the black and clear are ONLY joined to each other - NOTHING ELSE. However, in order to drop back to a single coil, an additional wire can be soldered to the junction of the black/clear, and that can then be switched on/off to earth. Essentially, what you are doing is earthing out one entire coil, so there will be no signal from that coil, as the signal flow then starts with starts at the clear, and ends at the blue. The coil with red/black having both ends to earth cannot produce a signal - it's inert!
What we've done is switch the blue and red over, (as well as adding the coil tap facility). The signal is still in series, through both coils, but starting at the other end, and this is the critical issue, when putting it in conjunction with the Higain, as it transpires that the Higain and the HB1 partially cancel each other out in normal use (destructive interference or "Out of Phase", but by reversing the signal flow direction we change the combined signal back to a state of constuctive interference, or "In-phase", which is the norm with 2 hi gains, or 2 HB1s.
It just seems that HB1s and Higains are naturally, and probably unintentionally out of phase!! So the simple mod of switching the blue to hot and the red to earth corrects it. Adding the coil tap isn't essential, but it is a nice option, as it lets you go back to almost stock 4003 sound, even 4001 sound, as the output is halved from approx 15K back to 7.5k.
Right - that's way too much physics for 8.45 am - where's my beer!
Apologies again for the dumbed-down science lecture! If your push pull knob is doing good stuff and you like it, well -
"if it ain't broke - don't fix it"! Have you wired it with a vintage tone 0.0047 capacitor, rather than coil tap, as the push pull is doing something?
Guy
PS - just in case: the HB1 schematics:
http://www.rickenbacker.com/pdfs/19521-HB1%20Wiring.pdf
