Gibson EB-1 wiring
Please forgive the ignorance of my question, I know how to solder and have been rewiring and repairing my instruments for years, always following the "put that wire there" instructions, without understanding how or what each component actually does.
So here's the situation: on my Gibson EB-1 (one pickup, one volume, one tone), there is a capacitor, .033, between the bottom lug of the volume and the center lug of the tone controle, I believe this to be a standard wiring configuration, no problem there. BUT, there is also a capacitor, very difficult to read, but I believe it says .01m 50v, soldered between the bottom lug of the volume pot and grounded to the back of the volume pot. The hot lug of the pickup is also soldered to this same bottom lug. The pickups ground is soldered to the top lug, and there is a wire going from the center lug to ground.
So the question: what is the purpose of that second capacitor, and would removing it change the sound of the bass?
BTW this wiring and the original pickup are not currently in the bass; I switched to a Dimarzio Model One years ago, along with Dimarzio push/pull pots.
Basic capacitor function is to bleed out treble from the signal path. So the bass would probably sound brighter without it in the circuit. Is that a 50's EB1? Hope you still have the original pickup, especially if it's the Bakelite covered single coil version.
1969, still have all original parts, bought in 1977. I've never seen another one in person, except for a 1956 model at Gruhns in Nashville that I was allowed to play.
I know the large cap bleeds the treble to ground, but that second cap is the one I'm wondering about. Would removing it from the circuit improve the sound?
The original wiring (1972) can be found in my wiring compilation ...
The EB-1 has a "flexible" tone cap at the volume pot. In 1972 it was a 22nF cap - but it might have been a 33nF cap in 1969. Especially as the EB-0 has a 10nF and a 33nF cap as standard.
The 10nF cap at the volume pot is a "fixed" cap. It is soldered at the volume pot - but "electrically seen" it is "directly parallel" to the pickup. Because soldered "fixed" to the pickup, it always bleeds the treble. This was the Gibson sound, bass players liked from the 50s to the 70s. It was mostly a flatwound time! Roundwound strings were very rare and only guys like John Entwistle did everything to get these roundwound strings ...
You can remove the 10nF cap.
Then you will get more trble - and the tone pot with the 33nF cap will work as it did before. Because the 10nF is wired in parallel, it can easily be removed and the bass / wiring works anyway ...
Hey Cadfael, you're the man! You're schematics are a great resource to the entire bass playing community. Somebody referred me to your site when I was researching what schematic to use for a custom bass I'm having made with a single thunderbird type pickup. Thanks a gazillion.
Thanx for your replies!
Didn't know the word gazillion (I'm German) ... :)
Now I know!
My word would be "beerillion" :D
Even more beer than you can imagine ... :D
My compilation is a mixture of schematic research (especially Gibson) and a mixture of schemetic research plus photo research and comparison (Fender).
Some custom ideas are "common", some are by others and sone are made by myself (a "wiring child of the early 80s").
I qouted the excellent Gibson bass site in my compilation. A lot of wiring photos (adding the schematics Gibson offers). I found some additional photos on search engines to varify the things I found out ...
The advantage of my compilation is that you can easily compare the Gibon schematics during time and find similarities between models of the same age.
By the way ...
Fender did "the Gibson thing" with its MusicMaster bass!
Fender also put in a "fixed" 22nF cap (parallel to the PU), adding the 50nF tone pot cap.
That's interesting about the MusicMaster. Of course Fender also got the design for their wide range humbucking pickup from a Gibson designer, Seth Lover, as well.
So it could be interesting to try wiring a 70's telecaster bass like an EB-0 or vice versa.
If one were so inclined they could do so using this link.
EB-0 on seite (page) 102, Telecaster bass on pg. 52
Just click on the pdf at the bottom of the page
This link should be a sticky.
(a Goethe fan???)
The MusicMaster had a guitar pickup on board. Some say it was a Strat PU but I think it was another guitar PU (because of the number of wirings). A guitar PU can work in a bass as well as a bass PU - but this was a "typical Fender guitar SC PU". So Fender might have added the fixed parallel cap to make it sound more "bass like" ...
The Telecaster II with its Seth Lover PU already has a (Gibson guitar PU like) humbucker on board and needed no additional cap. The Seth Lover is also known for not being the most brilliant PU. That's surely not the case for the MusicMaster guitar-SC PU (without cap) ...
I was thinking Beethoven more than Goethe and I also thought it was an appropriate screen name for a site than can have it's fair share of drama and turmoil. It also sounds cool.
So at what frequency does the secondary cap roll off?
Anyone out there know about the roll off of the second cap?
I don't know the exact frequency of the rolloff, but I can tell you that the .033μF (same as 33nF, I am used to the traditional nomenclature) capacitor does retain more mids in the mix when the tone knob is rolled off compared to the .047μF; and I like the additional mids so much I change out the stock .047 tone capacitor to .033 on all of my basses. It gives me that "second overtone" presence that gives more definition in the mix that I don't get with the .047. This helps my Fender flats retain their "growl," but when rolled off I can still get as mellow as needs be when desired.
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