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Low DCR pickups/ mudbucker question.

Derek Balonek

Derek Balonek

Mar 15, 2011
787
5
37
USA, CA, Sacramento Metro area
#1
I'm curious about pickups with really low resistance (read: less turns) and how they sound. I recall hearing that they are rather bright sounding.

I ask because the mudbucker in my EB3 appears to have a DCR of ~1k. For some reason I think that's off, it still has some heavy low end. There is a decent amount of brightness to it as well though, so maybe not? It doesn't seem like it's low on output, solo it's louder than the bridge 'bucker. Mixed the bridge overpowers it though. I'm not sure, I know it's supposed to be at least 8k.
 
#2
The EB3 mudbucker is supposed to be close to 30K, actually, but you'd have to unsolder it from the electronics to measure that, otherwise if you just measured at the ends of its wires you'd also measure everything else in the circuit.
 
#5
Is it a real Gibson EB-3, or an Epiphone? The Epiphone reissue has the mudbucker wound with heavy gauge magnet wire, so it only reads about 2k, and is kind of bright sounding, but the large gauge wire gets a lot of low end.

A real mudbucker is about 30,000 ohms (30k).
 
#6
It is the Epiphone version. So it's supposed to be that low? I do like the tone of it, but it isn't the 'bucker I've heard about. I thought to myself, well that's not so muddy! That explains it though. I suppose I like that it has some articulation though, and it still is quite fat.

It was of course a bit less bright before I ran it through a JFET pre though. Opamp pre was somewhere between that and no buffer.
 
#7
Derek Balonek said:
It is the Epiphone version. So it's supposed to be that low? I do like the tone of it, but it isn't the 'bucker I've heard about. I thought to myself, well that's not so muddy! That explains it though. I suppose I like that it has some articulation though, and it still is quite fat.

It was of course a bit less bright before I ran it through a JFET pre though. Opamp pre was somewhere between that and no buffer.
Click to expand...

Yep, it's almost like the Jack Casady pickup.

I like what JFET preamps do to the tone. I used to have a real Mudbucker in my Rick with a JFET buffer. Later I rewound the mudbucker to about 12k. It was a nice tone. Deep but clear and articulate.
 
#8
SGD Lutherie said:
Yep, it's almost like the Jack Casady pickup.

I like what JFET preamps do to the tone. I used to have a real Mudbucker in my Rick with a JFET buffer. Later I rewound the mudbucker to about 12k. It was a nice tone. Deep but clear and articulate.
Click to expand...

I see. It is a nice pickup. I've been eyeing the Artec one, since it is up there near 30k and I found some around $20 on ebay. Of course, I suppose the cost says something, but it might be cool to try out the mud.

The JFET is a great little thing. I hear people comparing them to tubes a lot. They can sound pretty warm in some cases, depending how you set them up.
 
#9
Derek Balonek said:
I see. It is a nice pickup. I've been eyeing the Artec one, since it is up there near 30k and I found some around $20 on ebay. Of course, I suppose the cost says something, but it might be cool to try out the mud.
Click to expand...

They sound like the real thing.

The JFET is a great little thing. I hear people comparing them to tubes a lot. They can sound pretty warm in some cases, depending how you set them up.
Click to expand...

Yes, they distort a lot like tubes too.
 
#10
I have about 20 J201's (Fairchild) and I couldn't get ANY of them to bias correctly. I tried varying the source and drain resistances all over the place for days and I gave up. I could never get a mid-bias point so I never bothered to hook up my scope. Maybe I got a bad batch or maybe they were Chinese clones, I don't know. J201's are not manufactured anymore. Another reason to give up, but I never wanted to give up. There's things like family and a job. Had to throw in the towel and move on.
 
#11
bumperbass said:
I have about 20 J201's (Fairchild) and I couldn't get ANY of them to bias correctly. I tried varying the source and drain resistances all over the place for days and I gave up. I could never get a mid-bias point so I never bothered to hook up my scope. Maybe I got a bad batch or maybe they were Chinese clones, I don't know. J201's are not manufactured anymore. Another reason to give up, but I never wanted to give up. There's things like family and a job. Had to throw in the towel and move on.
Click to expand...

I've been making JFET buffer/boosters based on the Alembic Stratoblaster since the mid 80s. I've built a bunch on the MPF102s from RadioShack. It's a self biasing circuit, and has a gain control if you need a boost. Works great with low output pickups. You can find the schematic all over the Internet. For use with bass, I increased the value of the output coupling cap to 5µF.
 
#14
Derek Balonek said:
It is good to know I don't have a bad pup. I think I'll pick up the Artec though, just to try.

David, how is the Stratoblaster self-biasing? Is the drain resistor set up to put half the supply at the drain or is there something else I'm missing?
Click to expand...

Here's the Stratoblaster circuit:
468d1174315690-blaster.gif


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Look at page 3;

The self-bias circuit (Figure 5) establishes the Q-point by applying the voltage dropped across the source resistor, RS​, to the gate. Since no voltage is dropped across RS​ when ID​ = 0, the self-bias load line passes through the origin. Its slope is given by –1/RS​ = IDQ​/VGSQ​.
Click to expand...

In this circuit, RS​ is the 12k resistor to ground, and RD​ is the 22k to VDD​.
 
#15
Yes, David. I have an entire folder of JFET preamps. Never felt like using the MF102's, as they were (if I remember correctly) more power-hungry and their gain wasn't like a J201.
I guess this is a topic for another thread and probably has been covered elsewhere here, but thanks for the circuit. I think there's a trade-off with that big source cap and input overload level.
I started to go in the other direction as in just a simple buffer to give me a low Z output from my bass to a compressor, but I never bothered with that simple circuit either since I went wireless with a Line6 G50.
Thanks for your contributions to the forum, David.
I'd like to see a multi-stage JFET circuit to give me some kind of tube gentle overload effect, maybe with individual level control between stages to facilitate gain-structuring. I could build it if I had the time, but again, I feel like I'm hijacking this thread.
 
#16
Here's the one I was going to build. I think the input impedance is half the value of the divider resistors, which would be 500K in this case.
 

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#17
Bumperbass, NTE sells J201 replacements. I believe it's the 458. I've personally had good luck with the 457. For tube-like FET circuits, you should check out runoffgroove.com. My current pre is based off their Fetzer Valve. They have a lot of nice designs, one if which is based on the B15.

You are correct on the impedance of that circuit. Source follower is great for buffering but it doesn't provide any gain; in fact gain is often a bit below unity.
 

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