Pick up question for Wolf and others
 

Ok it's pretty well known here I love my Gibson Thunderbirds. At this time I have two, a 1979 and a 1976 both are my daily drivers. For years everybody has told me the 79 sounds really big compared to the 76. I of course notice it too. The 79 has a huge deep rattle yer nuts sound while the 76 is thin and more like say a Fender bass. The difference is notable on the volume knob as well. If I switch from the 79 to the 76 I have to increase my volume by at least 3 numbers and even at that it lacks the presence that the 79 has. I took them both to a local guitar guy and he measured the impedance on both of them and the pick ups are identical. I want the 76 to sound like the 79 but I am at a loss and in need of more professional advice here. I will send it to you if you like Wolf. Replacing the old pick ups and putting them away is not out of the question as long as the new ones fit without alteration and will give me the sound I want.

Side note: yes the 76 is the one I refinished...here is is done. I found it's original PG in a bunch of old band clippings I'd saved.

http://forums.pelicanparts.com/uploa...1291857139.jpg
http://forums.pelicanparts.com/uploa...1291857157.jpg
http://forums.pelicanparts.com/uploa...1291857176.jpg

What about the magnets? If impedance is the same, what other variables are there? Same shape / size I would assume.

Come on Wolf! I want to know as well.
Larry

Ok.. a couple things I can think of here.
First thing that comes to mind is that if the control pots on the '76 are wonky (read; out of spec) that can cause a noticeable difference in volume and toen sweep. I'm not real up on Mini-humbuckers (especially on basses), but I believe they should use 500k pots. Check. If they read much lower than the pots on the '79, this could account for the volume difference. Choking the output, basically.

The other thing.. even though the pickup may read identical resistance, the output may not be the same. Kohms resistance really has nothing to do with actual output. It's all about the millivolts output...
Even though both pickups may have exactly the same number of turns of wire, the tension that the coils were wound with may be different, which will affect size the the coil... even the actual diameter of the wire... A smaller coil will produce more millivolts output when compared to a larger coil, even though they are "ohm identical" - this is basically because more coil deeper inside the magnetic field to produce current. The smaller coil pickups will also give a brighter, "thinner" sound, all other factors like magnet strength being equal.
Magnet strength also plays a huge role. Stronger magnets will usually mean more output. Supposing the coils on both guitars are the same (they should be pretty dang close) the weaker magnets will, again, give less output... BUT... will generally NOT sound thinner.. they'll be warmer, smoother, and sweeter sounding... generally. At least, this is so of 6-strings...

.

It's a very fine balancing act.

I'm betting on the culprit being the pots and magnets... I'd be happy to check the gauss and recharge the magnets for you if they're weak.

Ohh yeah... is the '76 heavier in weight than the '79? Wood density...

so many things....

bumpity, to make sure Targa sees this.

oddly enough, this was the first thing I thought of

Heywood Wakefiled chairs in that photo?

Odd that you should ask about weight. The 79, the one that sounds so good, has a pickguard that is made from a 1/4" thick piece of mirrored glass.. It adds a few ounces to the weight to it. I have often wondered if it effected the sound as it is glued not screwed to the body. I'm sure it has to change something. If I were to send the works out to you, would you want the whole guitar of should I just send you the electronics? Brighter and thinner describe the 76 sound to a tee.

Yes it's Heywood Wakefield. The house is a mid century modern design so we have a bit of his stuff around here.

im guessing the impedance would have been different if so, but is it still possible someone in the past removed some of the windings on the pickups to lower the output?

are the pickups the same exact distance from the strings on both instruments?

im not an expert but i would guess that the pots are causing the difference. perhaps at one time the pots went bad and were replaced or, are factory installed but are different than the other instrument

The 76 is obviously defective... I would be glad to take it off your hands for you... but only because you are family

This brings up the point that if you are going to buy a guitar go out and play a bunch of them (same model that is)

Guitar center had a sale on Mexican Strats so my friend wanted to buy and took me with him. As we walked into the store there were lined up at least a dozen Strats. I went down the line and played with every one... while his wife was picking out one that was a color she liked... after a while I picked one out and handed it to him... he bought it. Everyone who has played it thinks it sounds and plays as good as an American Strat.

Just the pickups alone, if you're able to test the pots specs yourself.
I'm betting that if you striped all the hardware off both guitars, you'll find that the '76 is heavier. Weigh them both with all thier hardware on and let us know. A few ounces shouldn't make much of a difference... Denser wood, I've found, will affect tone and overall volume in huge ways...brighter, thinner, stiffer sound.
The mirrored pickguard on the '79...might make a difference, but being that it's mounted on the wing instead of around the pickups, I don't think it would be that noticeable... if it were around the pickups, like a strat, the hard, stiff glass could transfer more solid vibration to the pickups directly.


You could send both sets of pickups and I could compare the gauss levels of the '76 to the '79. A simple test you could do at home would be to stick a screwdriver to each pickup at several locations and do a "pull" test... which one pulls the hardest on the screwdriver? Don't forget... two magnetic fields in each pickup! Test each one...

Check that too...make sure they're the same!

the set ups are identical. It was my first suspect so i measured it all carefully. these are the old sealed pick ups so no chance of anybody getting in there.

Sealed... how? Epoxy potted? or soldered on covers?
I should still be able to charge the magnets even with the covers on.

Wolfe, I'm playing tonight and I will use it as my back up bass. I'm off for a few weeks after that so if you PM me your address I'll gut the beast and send the innards your way.

if you cant solve your problem, you might be able to correct the volume and tone with a BBE Sonic Stomp pedal.

http://www.bbesound.com/products/stomp-boxes/sonic-stomp.aspx

i have used it for guitar and it works great....adding volume and tone without coloring the sound. when you use the louder bass, click it off...when you use the quieter bass, click it on...

i assume they work as well for bass as they do guitar