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Posted

Update: I've finally got around to slapping a pair of 10K resistors in line with the pickup wires and it seems to have cured the distortion. I'll take it along tonight and give it a blast during sound check

Posted

[quote name='Prostheta' timestamp='1448731798' post='2917740']
Interesting. Curious as to why that would work....
[/quote]

Are the resistors attenuating the signal level so it doesn't overload the pre-amp input stage?

Posted (edited)

That was my theory - to attenuate the signal a bit. Fingers crossed it seems to have worked

Edit: I'll check it for volume against my passive P tonight. I guessed at the resistor values, so may have overdone it. Sounded ok though my practice amp (old tatty powered monitor wedge)

Edited by Norris
Posted

I take the phrasing of my previous message back; I understand in theory, however the input stage of the differential preamp has more or less a 14-18v peak to peak range before you start banging the rails. I doubt that any passive pickup is that hot by a long margin....even a hot dual ceramic bucker like an MB-I/1E!

Regardless....it's good real-world information to take on. I'll pick this up with Veijo sometime soon.

Posted

What you'll have done is to set up a voltage divider. The input stages of each half of the differential preamp have 470k pull-down resistors. Refer to this:
http://www.calculatoredge.com/electronics/voltage%20divide.htm

It's not that straightforward, since the pickup itself has a DCR of about 11,8kOhms. Still, you can see the concept. Rb is the pull-down resistor, you have simply added Ra.

Posted

I've been pondering this a little more. It's been a long time since I played with analogue electronics, but in a passive circuit the pickup induces the current. It can therefore be considered a kind of AC battery for the sake of the circuit. The resistors are acting as shunts. The fact that they are in an active circuit shouldn't change anything as the pickup is still providing the impetus.

There again, I've had a couple of glasses of wine :D

Posted

I'm not at all sure how I've missed this thread before, but that is a [i]stunning [/i]restoration. Top job.

Pleased you did the update - not only that you've sorted the electrics but because I'd have missed this otherwise!

Posted

I've not sorted the electrics yet - it's not gigable yet, but I think I'm on the right track.

Glad you like the resto - it was done by one of the instructors at my Monday night guitar building club, who has been a mate of mine for years

  • 4 months later...
Posted

As a bit of a coda on this, the lacquer has cracked/crazed in a couple of places. Andy isn't happy with it so he wants it back to refinish again. He's a top bloke is Andy!

Btw, whichever BCer has the Ibanez Musician with Andy at the moment - that's a gorgeous bass! I'm wondering what all the knobs do though :)

  • 1 month later...
Posted

Now that I just plain weird. Hours before the Midlands Bass Bash, I was frantically swapping resistors around trying to get a reasonable sound out of it. Then I finally decided to get rid of the resistors completely again and find out just how bad the overloading was. As I un-soldered the resistors I accidentally over-stressed one of the cables and it broke. Having re-made the broken connection... no distortion. The only issue now is that my passive Squier is about twice as loud as the active Aria.

There definitely seems to be something up with the wiring. I'll have to see about getting a new molex connector and re-making all of the connections. I'm not convinced that it is making a good connection with the terminals on the pre-amp

Posted (edited)

[quote name='Norris' timestamp='1431370053' post='2770640']
[b]Where There's Muck There's Brass[/b]

The hardware that came off the bass was pretty grimy. Andy took his dremmel to the brass bridge, nut and back covers. T

[/quote]
I bought a SB-1000 Mk I off a guy in Manchester about 4 years ago. This thread inspires me to restore it.. Mainly a refret, the body work is in pretty good nick, but the frets are badly worn.

Did you lacquer the bridge or leave as polished brass?

Thx
Mark

Edited by Mark Dixon
Posted

[quote name='Norris' timestamp='1431201440' post='2768809']
[b]A Bass Barely Alive...[/b]

(We can rebuild it!)

OK, here are some 'before' shots. Remember - I did warn you!




[/quote]
Glad to see the case is in better condition than mine!!

Posted

[quote name='Mark Dixon' timestamp='1463173689' post='3049357']

I bought a SB-1000 Mk I off a guy in Manchester about 4 years ago. This thread inspires me to restore it.. Mainly a refret, the body work is in pretty good nick, but the frets are badly worn.

Did you lacquer the bridge or leave as polished brass?

Thx
Mark
[/quote]

The bridge was just polished up with a Dremel wire brush I think. It wasn't lacquered because it will always chip and then need stripping to clean up again

Posted

[quote name='Mark Dixon' timestamp='1463173903' post='3049358']

Glad to see the case is in better condition than mine!!
[/quote]

It's not stable enough to carry the bass. I might try to fix it but some of the ply is pretty damaged and not easy to repair

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