Re-wiring a preamp in my EUB

HeavenOnAStick · #1 03-01-2007, 09:33 AM

Hey guys. I just recently got an external preamp for my Palatino (an EUB). I'm wondering how I can get it installed in a way other than just putting a cable from the output of the bass, to the pre-amp, to the speaker/mixer/combo. I also want to get the least amount of buzz as possible (the main reason I bought the new preamp). Should I just disconnect the cable from the piezo pickup to the output, then have a cable going externally from that to the preamp strapped on to the bass? And by doing that, bypass the on-off switch, batter compartment, and volume/tone controls (which I'm guessing is where the amp is)? Will that get the purest signal, and get the least amount of buzz, or is there something else I should do?

HeavenOnAStick · #2 03-01-2007, 12:25 PM

When I posted this, I didn't realize that there was an Amps, Mics & Pickups forum in the Double Bass section. So if a Mod could move this to the appropriate forum, that'd be great. Thanks.

**Ívar Þórólfsson** · #3 03-02-2007, 12:56 AM

Quote:

Originally Posted by HeavenOnAStick

When I posted this, I didn't realize that there was an Amps, Mics & Pickups forum in the Double Bass section. So if a Mod could move this to the appropriate forum, that'd be great. Thanks.

Consider it done.

**Francois Blais** · #4 03-02-2007, 05:55 AM

I'm asking another mod to move this to the EUB forum!
Sigh...

**Bob Gollihur** · #5 03-02-2007, 01:34 PM

Quote:

Originally Posted by HeavenOnAStick

Hey guys. I just recently got an external preamp for my Palatino (an EUB). I'm wondering how I can get it installed in a way other than just putting a cable from the output of the bass, to the pre-amp, to the speaker/mixer/combo. I also want to get the least amount of buzz as possible (the main reason I bought the new preamp). Should I just disconnect the cable from the piezo pickup to the output, then have a cable going externally from that to the preamp strapped on to the bass? And by doing that, bypass the on-off switch, batter compartment, and volume/tone controls (which I'm guessing is where the amp is)? Will that get the purest signal, and get the least amount of buzz, or is there something else I should do?

I think that's what I would do (not seeing it in person), assuming the cable from the piezo pickup is completely shielded. If it is not I would consider either shielding the cavity completely with copper foil or shielding paint OR replacing the pickup cable with a shielded one. You are wise to locate the preamp as close to (on the bass) the bass as possible.

While you are there I'd check the quality of the output jack- I've no idea what they use, but if it's cheesy and you're already in there soldering, you may as well put a good quality jack in place.

ToneRanger · #6 03-04-2007, 08:58 PM

I have an old Boss FA-1 preamp installed in my EUB. I lined the cavity with copper foil and used a little PCB 2-pin connector to attach the pickup.
If you're having buzz issues, you might find you also need to shield the pickup with copper or aluminium foil (I don't know whether Palatino do this)

HeavenOnAStick · #7 03-06-2007, 08:42 PM

I did the soldering job, and everything is working fine (I have only played it through a house mix, so I don't know about buzz).

I've got some questions for sheilding it though (I've never done it):

The copper foil, can I just get that at a hardware store? And do I need to sheild the whole cavity? (With the EUB, that would be quite a job). Or can I just wrap it around the cable? With the pickup, if I wrap foil around that, wouldn't it affect the sound?

**Bob Gollihur** · #8 03-07-2007, 05:55 AM

Here's a resource I found by googling 'shielding a guitar' http://www.guitarnuts.com/wiring/shielding/shield3.php

It may not be necessary, I'd examine the wiring and do a high volume amp test to see. Often if you move the bass to within a couple feet of the amp you'll hear some noise.

ToneRanger · #9 03-07-2007, 06:35 PM

Quote:

Originally Posted by HeavenOnAStick

The copper foil, can I just get that at a hardware store? And do I need to sheild the whole cavity? (With the EUB, that would be quite a job). Or can I just wrap it around the cable? With the pickup, if I wrap foil around that, wouldn't it affect the sound?

Like Bob says, it may not be a problem - turn up the amp and see if the hum & buzz is acceptable.

I've found that piezos are very succeptible to intereference before the preamp, and all wiring (including the pickup) needs to be shielded for silent performance.

I use 3M 1181 EMI Copper Foil Shielding Tape with conductive adhesive. Check the online electronic suppliers. I think Stewmac sell it too, although there's some extravagent prices about. It's quite thin, so doesn't seem to affect piezo performance, and the conductive adhesive means you don't need to solder it (see http://www.fittell.id.au/piezo/ )

I'm told many hardware store sell copper foil (although around my place they don't). I think it would a lot thicker and not as suitable for pickups, however lining cavities or wrapping preamps should be OK. Just make sure it is connected to ground somewhere.