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Post by newey on Jun 17, 2012 7:06:33 GMT -5
bmic-
As far as the inductor goes, you are correct, you'll want to use pins 6 and 4. The two middle pins (2 and 5) are for the coil taps, to use 1/2 of either the primary or secondary coils.
On the model you bought, the primary impedance is 7KΩ, while the secondary is 10KΩ. Note that I said "impedance" and not "resistance". The resistance numbers are given on the data sheet.
Look closely at the bottom of the unit. Even if the pins aren't numbered, there ought to be a dot or some sort of marking to designate the #1 pin. You may need a magnifier.
If that still shows zippo, you can check the resistances with your multimeter. However, the difference between primary and secondary is minimal here (15Ω), so you'll need a good meter, one that reads to 3 significant digits, to tell the difference. Given production variances, it may be tough to tell anyway.
An LCR meter can be used to read the inductance directly, but I'm assuming that you don't have one of those, as they're pretty costly compared to a regular DMM.
In any event, with the primary and secondary so close in value on this unit, I'm not sure whether using the primary versus the secondary is going to be a critical issue. I don't know for sure, because I've never used one of these, but ChrisK notes that, at 7K impedance, the inductance works out to be 1 Henry. at 10K, it's 1.6. Whether that makes an audible difference or not, I don't know, but it's probably fairly minimal.
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n0nspaz
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Post by n0nspaz on Jul 5, 2012 20:48:25 GMT -5
hi, i would like to use this circuit in between 2 transistor based buffers to eliminate any loading. could i then scale down the pot values to improve signal quality? what pot values would you suggest? I have a novice understanding of RC circuits, so any help with calculating the rest of the component values is also appreciated. TIA... What adjustments can I make to the passive EQ so that it functions in the right direction, even if not in the right frequency bands, I don't mind being a guinea pig for it. I'm only wedded to the pot values as they are what I have already, but I would assume in theory I could modify those well enough with static resistors (I assume in theory I could be wrong as well). Like I previously mentioned I drew the schematic based on my best impression as the final point before testing in the original thread. I'd change the configuration of the bass-cut circuit. Think treble-bypass on a volume control, but limiting the amount of volume cut. I'd also locate it after the mid-cut, so they won't interact. I also think the value of the cap for the bass cut needs to be smaller. I suppose my only question would be, how would the wiring be different if the EQ is behind the volume (as it would be outside the guitar)? You could build it outside the guitar for testing, but don't turn the guitar volume down. Else this will add resistance in series, before the tone-cut networks. This make them much more effective when the volume is rolled down a bit and less effective when the volume is at max.
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Post by reTrEaD on Jul 7, 2012 5:19:57 GMT -5
Hi n0nspaz, Instead of scaling component values, it would probably make more sense to add resistance in series with the output of the first buffer. The greatest benefit in hum reduction will be from your second buffer driving the cable. The low impedance of that buffer will greatly reduce the amount of hum induced into the cable and also negate the treble loss associated with rolling back the volume control.
If you want to discuss this further, it would make more sense to continue the discussion on your own thread.
Cheers.
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bmic1980
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Post by bmic1980 on Dec 15, 2012 19:23:51 GMT -5
Sorry for the long absence, been busy with other things and trying to get the body refinished. Unfortunately I'm going to repaint it again next summer after some of the paint peeled off the back edge after having it sit in a guitar stand overnight.
Anyways, Its pretty much done, and its off getting setup now at a local guitar store. However, I'm having problems with pickup selection. The super switch is working just fine, at least the right pickups output in the right positions.
The problem is in the bypass position and on the standard switch. In positions 1 and 5 I have no output from the neck and bridge pickups respectively. In positions 2 and 4, they do have output with the middle pickup as they should. I'm using a megaswitch S for the standard switch, and both sides are bridged across for connectivity. All I can think of is a bad switch, but I'm wondering if anyone else has any ideas? Its especially weird that they output when in conjunction with the middle, but not by themselves, and they output off of the megaswitch ruling out the pickups themselves.
Thanks again for all the help.
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Post by newey on Dec 16, 2012 0:50:41 GMT -5
bmic1980- I don't know if this explains your problem or not, but I note that you are using a Megaswitch S as opposed to an "import-style" Strat switch. The Megaswitch S has a different lug assignment than "import-style" Strat switches. Megaswitch "S" datasheetOn your translation of the "double-barrel" scheme (from JA's original G-Nutz1 website), you show it as if it was wired to an import-style 5-way switch, with lug #4 as the output, lug 1, 2 and 3 get the "hot" connections from the three pickups, with the middle going to lug #2. This is as it would be on an import 5-way. But the datasheet for the Megaswitch S shows the middle pup wired to the #1 lug, with the neck to #2. Again, I don't know that this explains everything, but it would be where I would start to look.
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bmic1980
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Post by bmic1980 on Dec 16, 2012 15:46:18 GMT -5
Newey,
I had it wired incorrectly the first time, (not only neck to 1 and mid to 2, but the whole thing backwards as I had the switch backwards due to fitment...) and when I tested it I had pickups coming out the wrong switch selections, but after switching it to Middle to hot one and neck to hot 2, I still had no output on neck or middle. The fact I have neck and bridge outputs in 2 and 4 respectively is what is throwing me the most.
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Post by newey on Dec 16, 2012 16:33:49 GMT -5
OK, well, if that's not it, then it is possible that the switch is faulty. Not likely, but I can't explain how you'd be getting 2 and 4 either.
These switches use a PCB with traces for the connections, I suppose it's possible to melt something with a bit too much heat. Testing the switch will need to be done with it disconnected.
But you also said, concerning the Megaswitch, that:
Your original diagram only showed one pole of this switch being used, so I'm not understanding the reference to "bridging across". Is there something wired to the other pole of the Megaswitch?
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bmic1980
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Post by bmic1980 on Dec 19, 2012 1:45:10 GMT -5
Well I still don't have it back form the guitar store, waiting on the neck to settle back in after having been off and unstrung for so long, should have it back before the end of the week.
Newey, as far as "bridiging the swiitch," its just like the original concept on the guitarnuts site. Contacts 1 and 5, 2 and 6, 3 and 7, and 4 and 8 are are bridged together in those pairs.
After I get it back I'll see about getting a meter (I don't have one, but then again, I don't do to much of this stuff) and testing the the swtich after disconnecting it. I assume I should be looking for connectivity between the appropriate poles depending on switch position and the common (4 or 8) when testing, that about right?
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Post by newey on Dec 19, 2012 6:10:13 GMT -5
Still not getting what you mean. The original John Astley diagram uses one pole of a std Strat 5-way. Your version uses one pole of a Megaswitch. On neither diagram are the two sides of those switches bridged together. But that (probably) hasn't got anything to do with why you're not getting positions 1 and 5. A multimeter is essential for anything more than basic troubleshooting, and this wiring scheme is anything but basic. But to check the switch, all you really need is a continuity tester. One can be cobbled together out of a battery and a flashlight bulb, plus some wire and alligator clips. But, spend the $15 to get a meter, it'll pay for itself in the long run. With a meter, you're looking for 0Ω resistance between the lugs. In position 3, you should get connection between lugs 1 and 4. In positions 2 and 4, both lug 3 and 1 or 2, respectively, should be connected to the commons at 4. And, no need to check 5-8 since, again, I can't see where anything is connected to that side of the switch . . .
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bmic1980
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Post by bmic1980 on Dec 19, 2012 14:23:47 GMT -5
Newey,
it's not shown on the diagram, nor did John Astley show it on his diagrams, but in his actual photos (6th from the diagram) shows where he ties the two poles together for "reliability." I had done the same, that all.
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