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Re: Extech readings

5/21/2006 6:08 PM
Dave Stephens	Re: Extech readings How do you get resonant frequency from capacitance and inductance? Can you do this directly measuring from the pickup itself? Dave

5/21/2006 7:57 PM

Joe Gwinn

On 5/22/2006 12:08 AM, Dave Stephens said:

quote:
"How do you get resonant frequency from capacitance and inductance?"

You measure the inductance of the pickup and the capacitance of the guitar cable plus amp input (the cable dominates), assume that the pickup itself has ~100 pF of self-capacitance, and compute the resonant frequency of the pickup loaded by the cable and amp.

quote:
"Can you do this directly measuring from the pickup itself?"

Yes, if the cable is included, using the right equipment, a scope and signal generator.

5/21/2006 7:54 PM
Greg Simon	I'm in the process of refinishing the guitar right now so it is completely disassembled. I took the pickups out completely and will be showing Dave on Wednesday. I can also take some pics and email to you if you'd like to see Joe. They are WEIRD. I can see the epoxy, and the samarium cobalt magnets, and some connectors on the bottom that they solder the wires to. I'm not sure about other metals near the coils...I'll see what Dave has to say when he gets a look at them. You could probably measure the capacitance from a cable and amp, call it a standard value, and then add that to whatever the capacitance is of whatever pickup you're measuring right? Or does it change depending on the loading from the pickup? Regardless, I won't be able to measure it until I get the guitar refinished and back together...a couple weeks anyway at the least. I'm not sure what you're talking about as far as isolating things since the pickups are being measured directly to the Extech right now to get those specs. They were made with 4 conductor cable, but they only use two, and the others are clipped and buried in the shielding. I don't feel like taking those others out since I'd have to redo the connector and restrip wires and stuff. Maybe before I put them back in I might do it. We'll see. I'll see if I can get some pics together to show you. Greg

5/21/2006 7:54 PM

Greg Simon

I'm in the process of refinishing the guitar right now so it is completely disassembled. I took the pickups out completely and will be showing Dave on Wednesday. I can also take some pics and email to you if you'd like to see Joe. They are WEIRD.

I can see the epoxy, and the samarium cobalt magnets, and some connectors on the bottom that they solder the wires to. I'm not sure about other metals near the coils...I'll see what Dave has to say when he gets a look at them.

You could probably measure the capacitance from a cable and amp, call it a standard value, and then add that to whatever the capacitance is of whatever pickup you're measuring right? Or does it change depending on the loading from the pickup? Regardless, I won't be able to measure it until I get the guitar refinished and back together...a couple weeks anyway at the least.

I'm not sure what you're talking about as far as isolating things since the pickups are being measured directly to the Extech right now to get those specs. They were made with 4 conductor cable, but they only use two, and the others are clipped and buried in the shielding. I don't feel like taking those others out since I'd have to redo the connector and restrip wires and stuff. Maybe before I put them back in I might do it. We'll see.

I'll see if I can get some pics together to show you.

Greg

5/21/2006 8:09 PM

Joe Gwinn

On 5/22/2006 1:54 AM, Greg Simon said:

quote:
"I'm in the process of refinishing the guitar right now so it is completely disassembled. I took the pickups out completely and will be showing Dave on Wednesday. I can also take some pics and email to you if you'd like to see Joe. They are WEIRD. "

I would like to see them. From lots of angles, using ringflash and/or light tent, if these are available. Ringflash is particularly effective for photographing electronics assemblies.

quote:
"I can see the epoxy, and the samarium cobalt magnets, and some connectors on the bottom that they solder the wires to. I'm not sure about other metals near the coils...I'll see what Dave has to say when he gets a look at them. "

OK.

quote:
"You could probably measure the capacitance from a cable and amp, call it a standard value, and then add that to whatever the capacitance is of whatever pickup you're measuring right? Or does it change depending on the loading from the pickup? "

Cables vary widely in length and capacitance per foot of length, but pickup loading does not change the capacitance of the cable and amp.

quote:
"Regardless, I won't be able to measure it until I get the guitar refinished and back together...a couple weeks anyway at the least."

There is no reason to wait. You can measure cable and amp capacitance regardless of the condition or even existence of the guitar.

quote:
"I'm not sure what you're talking about as far as isolating things since the pickups are being measured directly to the Extech right now to get those specs. They were made with 4 conductor cable, but they only use two, and the others are clipped and buried in the shielding. I don't feel like taking those others out since I'd have to redo the connector and restrip wires and stuff. Maybe before I put them back in I might do it. We'll see."

I assumed that having 4-conductor cable meant that you could measure each coil. But if only two conductors are used, it won't work.

quote:
"I'll see if I can get some pics together to show you. "

Great.

5/22/2006 2:05 AM

Greg Simon

quote:
"There is no reason to wait. You can measure cable and amp capacitance regardless of the condition or even existence of the guitar. "

There is a reason to wait, and that is because I'm too busy with other things like stripping 2 colors of paint of the guitar, sanding it, sealing it, and refinishing it. Also fixing 3 Supro Thinderbolts for someone, working on my own amp, and working full time and sometimes overtime. I'll get to it when I get to it Joe.

quote:
"I assumed that having 4-conductor cable meant that you could measure each coil. But if only two conductors are used, it won't work. "

I think the other conductors are in fact wired up to the pickup, but it would require me stripping wire back to get at them to check. I may do this before I put the pickups back in, but as per above, I'm a little busy right now with other things.

I'll let you know when I have some pics available.

Greg

5/26/2006 11:24 PM
Greg Simon	Re: some more info Joe Hey Joe, Dave measured the magnets with his gauss meter on wednesday. These were reading around 469 or so, and that is a little higher than the A5 in the gibson humbuckers, but not as high as the Strat polepieces I think. Dave could elaborate on that further. They are epoxied, and the magnet is on the bottom of the coils, in between them like on a PAF. Right underneath that is a circuit board, and on either side of the magnet and the board are some metal strips. I'll take some pics when I get back from California early this next week and email you some. It is hard to see anything beyond the initial appearence of the pickups due to the circuit boar don the bottom and also due to the epoxy. John Hall, CEO of RIC told me they are mostly conventional humbuckers in design though, so I would guess the internals are just like a PAF, but with longer and narrower coils. Greg

5/26/2006 11:24 PM

Greg Simon

Re: some more info Joe

Hey Joe, Dave measured the magnets with his gauss meter on wednesday. These were reading around 469 or so, and that is a little higher than the A5 in the gibson humbuckers, but not as high as the Strat polepieces I think. Dave could elaborate on that further.

They are epoxied, and the magnet is on the bottom of the coils, in between them like on a PAF. Right underneath that is a circuit board, and on either side of the magnet and the board are some metal strips. I'll take some pics when I get back from California early this next week and email you some. It is hard to see anything beyond the initial appearence of the pickups due to the circuit boar don the bottom and also due to the epoxy. John Hall, CEO of RIC told me they are mostly conventional humbuckers in design though, so I would guess the internals are just like a PAF, but with longer and narrower coils.

Greg

5/22/2006 2:39 PM

David Schwab

Re: Extech readings

On 5/22/2006 1:54 AM, Greg Simon said:

quote:
"They are WEIRD"

You know, the Ric humbuckers are used on both the basses and guitars. I've always thought the DCR seemed really high to be a clean sounding bass pickup, but I guess that's why they used the magnets that they did.

I have heard them on a bass, and they were quite clear and clean sounding... which surprised me. But I can also see where that might make them sound harsh on a guitar.. which already has more high end. I remember Guitar player doing a review on one of the first Ric basses that used them, and they thought they were weird sounding, hollow and muffled.

John Hall said him and another guy designed them to be hi-fi sounding... but if that's the case, why so much wire?

In general I think Ric is over winding their pickups these days.

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