Preamp wiring

[Colledge]

i have this preamp to put into the 5 string fretless i made last year:


At the moment i only have a single MM style humbucker so the balance pot will just work as a second volume. Fair enough, but i was wondering if it is possible to wire up a piezo pickup into that second input. The bass has an unused cavity under the forearm contour which i figure would work well for a piezo pickup / a nice deep, thumpy sound.

Does a piezo need any extra preamp stage or buffer or would it work straight into the preamp.


I'd also like to clarify the use of the gnd connection.... i don't have any shielding (future job) and my jack connector doesn't have 3 terminals like in the diagram, should i connect it to the bridge ground?

cheers.

Edited November 24, 2010 by Colledge

[icastle]

[quote name='Colledge' post='1035151' date='Nov 24 2010, 02:58 PM']Does a piezo need any extra preamp stage or buffer or would it work straight into the preamp.[/quote]
It'll probably need a buffer - the impedance will generally be far too low without one.

[quote name='Colledge' post='1035151' date='Nov 24 2010, 02:58 PM']I'd also like to clarify the use of the gnd connection.... i don't have any shielding (future job) and my jack connector doesn't have 3 terminals like in the diagram, should i connect it to the bridge ground?[/quote]
The shielding is quite important - especially if you now have a preamp runing as well - you're liable to pick up a whole pile of buzzes and background "mush" without it.
The jack connector has to have three connections as shown as the "extra" connection is used as a switch to power on the preamp.

Edited November 24, 2010 by icastle

[Colledge]

right, so i have to get an active electronics specific jack connector then? and the wire i just noticed attached to the volume control housing should be grounded?

[Ou7shined]

You might not get all that much hum considering you are using a humbucker. Just a stereo jack socket is all you need.

[icastle]

[quote name='Colledge' post='1035202' date='Nov 24 2010, 03:55 PM']right, so i have to get an active electronics specific jack connector then? and the wire i just noticed attached to the volume control housing should be grounded?[/quote]

Yep.
You need a switched 1/4" jack socket and the rule of thumb should be that any large lump of metal that isn't "live" should be grounded - you certainly can't overdo shielding

[icastle]

[quote name='Ou7shined' post='1035216' date='Nov 24 2010, 04:04 PM']You might not get all that much hum considering you are using a humbucker.[/quote]

...until you add the proposed piezo of course, and whats a couple of inches of wire between friends...

Edited November 24, 2010 by icastle

[Colledge]

cheers for the advice. Copper tape is on the way.
i'm guessing [url="http://cgi.ebay.co.uk/Jack-Socket-Mono-Switched-6-35m-2-Pack-CN325-/150502433300?pt=LH_DefaultDomain_3&hash=item230aa4e214#ht_1185wt_907"]this[/url] does the job? it'll be going on an angled strat style mount on the rear control cavity, actually works out well for placement. pics when done.

[icastle]

[quote name='Colledge' post='1035242' date='Nov 24 2010, 04:24 PM']cheers for the advice. Copper tape is on the way.
i'm guessing [url="http://cgi.ebay.co.uk/Jack-Socket-Mono-Switched-6-35m-2-Pack-CN325-/150502433300?pt=LH_DefaultDomain_3&hash=item230aa4e214#ht_1185wt_907"]this[/url] does the job? it'll be going on an angled strat style mount on the rear control cavity, actually works out well for placement. pics when done.[/quote]

Yep - just the thing

[neepheid]

Won't you need a stereo jack?