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Author Topic: Help comparing preamp schematics - can you tell me why these sound different?  (Read 19606 times)

kvandekrol

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Awesome! That mod looks like it might be worth trying. Easily reversable, at least. Was the mod simulated using the 250k pot or the 50k?

phatt

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There are 3 sim sets.  They are named and colour coded on the left edge,,
 sorry not real clear.

Red/dark blue and purple are *tone off*
Light Blue/yellow /green are *full on*

50k=purple/green trace.
250k=dark blue/yellow.
Mods=Red/lightblue.   (note the red line is almost the same as dark blue)
Cheers, Phil.

kvandekrol

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sorry for the confusion — what I meant was whether the "Mod" on the chart (red/light blue) was simulated using a 50k pot or a 250k? You had mentioned changing C3, R6 and C13 to new values, but I wasn't sure whether you had started with the 250k pot or the 50k pot when you experimented with those mods.

Where's a good place to get those 3 components? I'm looking on Small Bear Electronics but I can't find the correct component values, and there are so many different types of capacitors that I'm worried I'll get the wrong kind... Resistors are easy enough, but the capacitor search is not going too well!

phatt

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Sorry the old brain fades off at times,, :loco
Yep I now see your point.
YES! a 250k pot was used for the mods.

The use of 250k pot *Full off* does at least impart very little colouration of the original signal. I have no idea whether that be a good or bad thing? sadly you can't *Hear* simulations. ;D

As to where to get parts *electrical hobby stores* Does depend where you live.

If you are prepaired to scrouge junk (Like I do 0:)) then trashing almost any unused home electronic device these days will reap heaps of Caps and Resistors.
Don't bother with computer mother boards and anything that uses surface mounted stuff.
Old video recorders and hifi junk from 20 years ago will have heaps of useful bits that can often be reused.
I collect so much *crap* (as my wife calls it) that I have to have a throw out day every 6 months.
Have fun with it,, it gets addictive after a while :loco  Phil.

phatt

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One more thing,,I get the impression that you are new to playing with circuits.
If so then;
If you mess with these boards be very carefull when unsoldering/resoldering components.
You will quickly learn that the copper tracks can't handle reheating to many times.
You can solder small standoffs of short wires thereby enabling quick value changes and  not heat stressing the track/solder pad on the PCB.
Phil.
« Last Edit: December 22, 2009, 07:29:42 AM by phatt »

kvandekrol

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Fairly new. My experience is limited to a couple of less complex amp repairs as well as a few effects pedal mods. Nothing too extensive...

Unfortunately I don't have access to much in the way of old electronic components... I found these capacitors on Small Bear, but they aren't the same type as the ones I'm replacing, so I'm wondering if they would work for this?

.0022 mf capacitor - This is .0022 instead of .002, and it's a Mallory 150 instead of the box style.

.015 mF capacitor - This is the right value, but it's a Sprague orange drop and is not the box-style one on the board...
« Last Edit: December 23, 2009, 08:28:24 PM by kvandekrol »

J M Fahey

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Hi kvanderkrol: I agree with the above statement: be careful with the PCB, it's the only "component" you can *not* buy over the counter.
Why don't you clone it, make a few, and build different variations without endangering your guitar?
Anyway, I think the sound difference you hear is 95% pickups and 5% electronics. (hint, hint)
Remember if you destroy your PCB your guitar will lose 80% of its market value and a replacement one, *if* available, will cost close to what the guitar itself costs, plus rising some uncomfortable questioning by the Fender staff  ("just *what* were you doing there with your soldering iron?")

phatt

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Hi kvandekrol,
                   Refer to above post and note the warning.
I second it,, Hint Hint
Phil
« Last Edit: December 25, 2009, 08:18:42 AM by phatt »

J M Fahey

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If you scan both sides of the board (you can scan "thick" objects too, not only paper), it's somewhat easy to trace the board; then you open the scan in Corel or some CAD package, assign it to a layer, and on another one you trace the board in black/white, almost the same as if you were holding a piece of tracing paper over it and using India Ink (the *old* way to do it).
With that handcopied "new original" you can make a few boards (or just one) by iron-on transfer or photo sensitive board methods.
You can also turn a "regular" Strat , original or clone, into a Clapton or Elite one (hint hint), which is a *good* thing. 8|