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Norlin Gibsons: Check For Tone Pots Resistances


capmaster

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Posted

This thread should become a sticky one...

 

The following may apply to thousands of Gibson guitars from about the mid 1970s to the mid 1980s.

 

Chances are they lack clarity and punch, and simply don't cut through in both stage sound and recording mixdown. Many Gibsons from that era were equipped with tone pots that severely load down any pickup you may try or have tried. So my advice to every owner of these guitars is the following:

 

Check the tone pot resistances or have them checked. If there are 100 kOhms to be found, don't hesitate and replace them with 500 kOhms types audio taper. This will FREE your pickups' tone.

 

When cranked up to ten, a 100 kOhms tone pot acts like a 500 kOhms tone pot when turned down to about four.

 

Be assured you will achieve a VAST improvement. Remember you will just have to turn down to about four when desiring the "old" tone.

Posted

In the linked thread, it went around a 1987 Les Paul:

 

http://forum.gibson.com/index.php?/topic/104877-neck-pick-up-muddy-sound-on-bass-strings/

 

Same was the case with my own 1978 SG Std, I know in person of two more mid-seventies SGs, and one late-seventies Les Paul.

 

The thread I linked above made me aware that this problem might still apply to many guitars out there that still have their original tone pots, and most owners don't even guess what their guitars could sound like.

Posted

Have to say all these electrics confuse me somewhat [cursing] . I've just had my guitar set up and the electrics looked at...( I was the subject of the linked thread). I have 100 ohm tone pots and the guitar tech told me that he thought this may well contribute to a treble tone bleed . So he thought he'd take the tone pot completely out of the circuit to see what difference the 100 pot was making and he said he couldn't tell any difference in the sound when he removed it and therefore thought that changing up to a 500 couldn't make any difference and therefore recommended I left it all alone ???

 

Please also see link below re another forums discussion on a 100k tone pot...

 

http://archive.ampage.org/threads/1/gtgd/002396/100K_pot_tone_control-1.html

  • 3 weeks later...
Posted

Have to say all these electrics confuse me somewhat [cursing] . I've just had my guitar set up and the electrics looked at...( I was the subject of the linked thread). I have 100 ohm tone pots and the guitar tech told me that he thought this may well contribute to a treble tone bleed . So he thought he'd take the tone pot completely out of the circuit to see what difference the 100 pot was making and he said he couldn't tell any difference in the sound when he removed it and therefore thought that changing up to a 500 couldn't make any difference and therefore recommended I left it all alone ???

 

Please also see link below re another forums discussion on a 100k tone pot...

 

http://archive.ampage.org/threads/1/gtgd/002396/100K_pot_tone_control-1.html

Look for a guitar tech with proper hearing, and leave the linked forum discussion alone. It is your tone, not that of a guitar tech or any other member of any other forum. Interrupting a 100 kOhms tone control with a 300 kOhms volume pot connected increases the midrange output by about 5.6 dB which is clearly audible.

 

.022µF are OK, 100 kOhms tone pots are just inappropriate for high impedance pickups. The impedance peak of a typical 4 Henry coil with typical 200 Picofarad coil capacitance is over 141 kOhms at 5627 Hertz while lows appear at the DC resistance of the coils, typically 8 kOhms. Assuming a volume pot of 300 kOhms, the treble range is dumped about 9.2 dB which leaves about 35% of level or 12% power. With a guitar cable of 600 Picofarad, the values are 71 kOhms at 3554 Hertz, a dump of about 7.4 dB with 42% of level or 18% power left in this distinctive midrange. Moreover, phase delay will additionally eat up punch and clarity.

 

For a 500 kOhms tone pot including 300 kOhms volume pot the values are for the pure pickup 4.9 dB dump which means 57% of level or 32% of power, including guitar cable 2.8 dB dump leaving 73% of level or 53% of power.

 

In fact, 2.8 dB loss compared to 7.4 dB means 4.6 dB to cut through, or 53% of power compared to 18%. Cutting the tone pot connection completely would provide just about 1.0 dB more than using a 500 kOhms tone pot.

 

If you don't trust the numbers, trust your ears. I quote here the advice I posted into another topic (see below):

 

"In case you want an impression what the possible change would be, just take virtually any electric guitar except stock-equipped Gibsons made from circa 1970 to circa 1988. Turn down tone controls to about 5...4 (or 6...5 on Fenders), play and listen. Then crank the tone controls up to ten, play and listen again. This comparison will give you an idea what will happen to the sound of your 1977 S-G." It applies as well to your 1987 Les Paul.

 

Quoted myself from this post:

http://forum.gibson.com/index.php?/topic/105888-hngd-1977-s-g-standard/page__view__findpost__p__1432226

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