Modding my Bass Guitar

I was getting increasingly frustrated with my bass guitar. Lovely Fender Jazz Bass though it is, beautifully resprayed in electric blue, there was a problem – despite the lovely bodywork, every so often it would sound out of tune even though it wasn’t. You could hear how nice and clean the strings sounded when plucked, with no amp, in a quiet room, but not necessarily through the amp. It never went out of tune, though, unless I knocked a machine head, and the action is very nice.

One thing about my bass, is that it had once had an active unit in it. There was an unused battery box and an extra output socket (which was wired wrongly so couldn’t be used). Hums, pops and clicks were the norm, and occasionally a very loud hum cured by fiddling around with the lead in the socket. Clearly, at some point, the owner had taken out the active stuff for another bass, and put in a passive unit and cheap, non-matching pickups. And didn’t make a very good job of it.

So the obvious thought came to mind. Why not get an active unit and restore it to its former glory? Also change the pickups while I’m at it?

EMG Pickups

emg-jhz

I decided on the EMG JHZ passive pickup set. Two reasons – they represented good value bought as a pair, and 3 of the reviews I read on the internet praised them for being very neutral. The only bad review I saw said much the same thing but found it boring. But if I’m going to add an active unit, I want a neutral sound being fed in. Sitting there with a 4-band equaliser on the bass means I can add my own colourations, or just leave it neutral.

Interestingly, the EMG pickups come with 5 pins on the bottom and a connector that slides over them, the middle pin going to the screen of the cable. At the other end, you get a black and white wire soldered together, which means that there are two coils facing opposite ways inside the unit, to cancel hum. The red wire is “hot” and the green wire is “cold” – however the screen wire is pre-connected to the green wire, which is fine if you are connecting to a passive unit. For an active unit, it’s not so clever and you need to separate the green from the screen.
emg-lead

It’s worth mentioning that there was an earth wire from the bridge, just hanging loose, when I opened up the old unit, which would explain a lot of hissing and popping. The jack socket had been bent out of shape. And the second, stereo-type, jack socket had the live from the first one connected to both channels on it. Meaning that when you plug in a mono jack plug, it shorts the signal to earth – which explains why that socket didn’t work. The wiring generally and the bent main mono jack probably explained why you had to fiddle with leads plugged into it to prevent buzzing. And you only had to set the two cheap, unshielded, pickups at different volume levels to generate hum. The twin-coiled and shielded EMGs, you would think, would sort these problems out.

Audere JZ6 control panel

I saw a picture of this and fell in love with it!

Audere JZ6

The Audere JZ6 jazz-bass control panel.

The knobs from left to right:

  • Volume over balance
  • Higher middle over lower middle
  • Treble over bass
  • 6-way impedance (Z) switch.

Apart from the Volume knob, the other 5 pots have a gentle “centre-stop” so you can find the neutral point on each setting. The Z switch  presents different impedances to the pickups. As they are basically magnetic coils like microphones, they have their own impedance. The combination of the two means that you get variations in the sound by different switch positions. From very bassy to quite thin and trebly. But always very clean, unlike the variations you get using tone controls. Still, the tone controls here are quite well behaved, only the lower middle presenting a slightly boomy sound when turned most of the way up, which may actually be quite useful in some circumstances.

At least, that’s what I discovered when I took the unit to the place where we practice, to plug it into my amp. I was a bit worried because I had to give the unit a bit of a push to get it in, what with all the wiring in the cavity, and I was worried about whether some of the earthing was a bit fragile. I connected a direct earth from the output jack, one wire screwed to the copper lining, one to the bridge earth wire, and one each to the pickups, all together, and it seems to have done the trick regarding hiss and hum.

LED Battery Indicator

Another nice feature of the Audere panel is that there is a little LED showing through it. When you switch on, it glows flat out, then a little less, then flat out again. How much less tells you how much juice is left in your battery. If the battery is getting low, it flashes for 5 seconds instead. On another variation of the panel, the JZ3, there is a 3-way toggle switch instead of the 6-way rotary switch, and the jack socket is on the panel. It’s designed so that the battery fits in the chamber with it as well, meaning that you can use it on a J-Bass with an unmodified body. To change the battery, you’d have to undo the 3 panel screws. Still, if you get the 5-second flash, you have 10 hours left – they claim a full battery lasts 250 hours. So not a problem – the first time you get a 5-second flash on plug-in, you play out your gig and change the battery before next time.

I had a 15-minute play on the unit, playing the same little run, trying different settings, and overall it’s great – and tuneful. I don’t seem to get off-key sounds being introduced. The real test will come on Sunday when the band will get together for a rehearsal. But so far I’m liking it.

Modding my Bass Guitar part 2

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: