Active bass replacing jack input.

stz · #1 10-09-2007, 10:16 AM

Hi, just a quick one.

I have had to replace a jack input on a tobias bass which was no longer making good contact. The active electronics are switched on by the jack being inserted, bridging the negative.

So the socket that came out of the bass had a single lug for positive and two for the negative. The negative lugs are where the on/off connection is made.

The one I put in and the ones I seem to only be able to source have a single lug for negative and two for positive. No problem thinks I. It is only a waveform. I'll just wire it back to front. The signal will only be of phase right?. This works, but now I get an ugly hum when I touch the strings. I'm guessing because before I was earthing the instrument and now I'm touching positive.

I double checked this by taking a guitar lead and swapping the polarity on one end. Fixed the hum.

So what I want to know is should I just try and obtain the exact part I need which may be tricky. Or is there another fix for the way this is wired? Any ideas?

stz · #2 10-09-2007, 02:41 PM

I guess I could check out a stereo connector? That would be bound to have all the lugs I can eat.

newfuture · #3 10-09-2007, 06:38 PM

The problem sounds like you've swapped signal hot for ground, which is why you're getting a lot of hum: the shield used to send RF to ground is now going straight to the amp. If you swap the two signal leads between the electronics and jack you'll probably be OK. If not:

There are two common ways to get power to active electronics:
1) {most common} use a stereo jack, with the sleeve being ground (signal and electronic), the tip being signal and the ring being the battery connection. When you put in a mono cable, the sleeve of the mono cable shorts ring and sleeve of the jack and powers up the on board preamp. Swithcraft #12b will do the trick.

2) {less common} use a switched jack that has a physical contact that gets made when a plug is inserted into the jack. This will have terminals for the switch that don't have to be the same as signal. Rickenbacker uses this scheme for Ric-o-Sound on their stereo instruments. The part number they use is 13. Yep, just 13.

Effectsconnection has them both HERE for cheap.

stz · #4 10-10-2007, 01:08 AM

Yeah that is what I've done but only because I need to use the earth to make the on/off and I can only find a mono jack in the style I need.

I need a barrel connector one. It is one of those jacks that mount on the side of the instrument and is maybe an inch and a half long!

I think I'll just get one of these. (It is a stereo)

http://www.maplin.co.uk/images/Full/hh22y.jpg

and unscrew it and hope that the inside is what I need.

newfuture · #5 10-10-2007, 10:24 AM

the maplin part might work, but is gonna be a PITA.

If you got to the US ebay site and search auction # 320164789796, that may be a better fit. I've also found Neutrik's website to be helpful in finding weird part numbers.

Switchcraft's part number for this is 152b, they're about $8-15us.

The connector you're using sounds non-standard. It's got 3 terminals, but is not Tip Ring Sleeve?

nastyn8c · #6 10-10-2007, 03:22 PM

Quote:

Originally Posted by newfuture

The connector you're using sounds non-standard. It's got 3 terminals, but is not Tip Ring Sleeve?

I thought most standard active basses were like that

newfuture · #7 10-10-2007, 05:07 PM

Quote:

Originally Posted by nastyn8c

I thought most standard active basses were like that

They are. I think the OP has the right part, but it's wired incorrectly.

spudmaster34 · #8 10-10-2007, 06:51 PM

Quote:

Originally Posted by stz

I need a barrel connector one. It is one of those jacks that mount on the side of the instrument and is maybe an inch and a half long!

I had a jack just like that crap out on my right before a gig, a quick band field-trip to a music store and they had excactly what I needed. Including explaining to the saleswoman why I really did want stereo not mono, it took about half an hour.
It might be worth asking at a repair shop or store.

stz · #9 10-11-2007, 05:31 AM

Hey I'll try and clear this up without confusing it anymore.

The one I took out had tip, sleeve, sleeve.
The one I got to replace it had tip, tip, sleeve.

The circuit switches on the sleeve connector. So I need another tip, sleeve, sleeve. What I was asking was if I go and find a stereo one. Will that have what I'm after? I'm guessing it has tip, ring, sleeve. The mono jack will short the ring and sleeve so I can just use that for my sleeve, sleeve switching. Confused yet?!

Failing that I'll just take a multimeter into Maplin and rip it out of the packet.

Philbiker · #10 10-11-2007, 07:20 AM

Quote:

Originally Posted by stz

What I was asking was if I go and find a stereo one. Will that have what I'm after? I'm guessing it has tip, ring, sleeve. The mono jack will short the ring and sleeve so I can just use that for my sleeve, sleeve switching.

That should be exactly what you need. Virtually all active guitar and bass circuits use a tip/ring/sleeve stereo input jack to switch the electronics on and off. Ring and sleeve complete the circuit when a mono cable is inserted into a stereo jack.

newfuture · #11 10-11-2007, 10:04 AM