servant
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Post by servant on Dec 22, 2007 15:26:33 GMT -5
Hi guys, Haven't been around much lately so hope you don't mind a cry for help. ;D My son has an SX bass that he bought as an upgrader/project guitar. It has a P-Bass and a J-Bass pickup, with a volume and tone for each. There is no pup selector switch. He replaced the pups and pots, and we wired it up following the 50s Les Paul wiring (as in www.specialtyguitars.com/kits/lp_diagram.pdf). While that works fine, it does not work like the original. The stock wiring ( www.rondomusic.com/photos/bass/wire301.jpg) allowed him to turn one volume all the way down, and it would not cut the other pickup out. As I'm sure y'all know, the Les Paul wiring turns off both pickups when you turn one volume down (hence "slicing" with the pup switch). Since the bass has no switch, looking at the LP wiring diagram, we ran the hots from the center tab of each volume pot to the hot tab of the output jack. Short of stripping everything out and rewiring back to stock, what do we have to change to get the "complete independence" back for the two volume pots? (In other words, we would like to keep the "better tone control" concept of the 50s LP wiring; we just want the volume issue resolved.) Thanks guys! Dean
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servant
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Post by servant on Dec 22, 2007 18:15:46 GMT -5
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Post by JohnH on Dec 22, 2007 23:08:04 GMT -5
Hi servant and welcome to GN2
I think your best simple bet is the original Rondo diagram that you posted. It shows how volume controls can be arranged to avoid that ''one pup cutting out the other" problem. It does this by wiring hots from the volume pot outer lugs rather than the inner lugs - it is often known as reverse wiring.
I dont have any experince with Bass pickups but on LPs, I am not usually in favour of that reverse scheme. On a guitar, I think it gives inconsistent output which is liable to tone loss due to the cable, and I also find that the problem of one volume cutting out both pups is not a problem in practice, because if I want to turn one pup right off, I can do so with the toggle switch.
But I can see that with no toggle switch as in the bass, it may be more important, and the tone issues are less apparent at the lower frequencies of a bass, and so reverse wiring may be preferable.
The other thing I dont like is that 50s wiring scheme of tone controls, which is often promoted on the LP forum and elsewhere, but not here. I believe it also causes tone havoc and mud at reduced volume if you also reduce the tone control.
OK - what would I do with that arrangement of 2v 2t and no switch? Id wire the pups in series, each with its own volume and tone, which would be fully independent. Then Id add a small active home-made no-gain buffer, which would really preserve the snap of that bass independednt of whatever you plug int or whatever combination of volume settings you use. As you combine the pups together, the signal will get more powerful too. If you are interested in that, I can help you with further info.
cheers
John
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Post by sumgai on Dec 23, 2007 1:16:20 GMT -5
servant, Hey, long time no see! Glad you're still with us! Sorry, but that's just not true. I can about imagine what the public outcry would have been like, back in '52 when the very first LP was released...... "Whaddya mean, the whole thing cuts out if I turn one volume down? That ain't what I want!! " No doubt back in the 50's, manufacturers tended to listen to testers a bit more closely, and thus Gibson avoided all the hub-bub before it ever got started. Just as the diagram told you to do.... which as you've now found out, is wrong. John's recommendation to use the Rondo wiring is dead-on, that is the way that all Gibsons have always been wired, when they have two or more pups and individual controls. (There've been some exceptions, but those were engineered to avoid the problem in other ways.) Again, simply reverse the leads on each of the volume pots - output to the jack is hooked to the outer terminal, and input from the pickup is hooked to the center terminal. Leave the wiring to the tone controls alone - in the new configuration, they'll be in the correct location. That's a loaded statement if I ever saw one! Let me presume that you mean the original LP, as built and shipped by Gibson - I'd agree, that's a tonality to die for. But that cluster**** from Specialty Guitars has it so wrong, we don't know whether to laugh or cry. One would think that if they're gonna try to sell you a 30X overpriced capacitor (times 2!), they'd at least use the correct wiring scheme. But then again, if they did that, they'd just be copying everyone else. Perhaps they think all of us players/builders have had it wrong for the last 55 years or so, ya think? </derisive sarcasm> HTH sumgai
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Post by JohnH on Dec 23, 2007 3:33:20 GMT -5
Sumgai – in the last year I’ve checked out dozenss of old and new LPs, Epis, Gibbos, Tokais, Grecos, and Cheapos, leading to me buying a Gibson LP Studio. They all, including all the Gibsons, have the forwards wiring where if you select both pups and turn one right down, they both go off. Its not really a problem, since if you really want just one pup, you can get it with the toggle switch and the adverse interaction only occurs at low volumes.
The other thing is, that ‘50’s wiring’ scheme as shown by Speciality Guitars, in which the tones are after the volumes does get a lot of favourable discussion – for no good reason that I can see, but its not just one diagram in error. It’s all over the wiring discussions on the LP forum. Unfortunately that’s all in their ‘members only’ section, so I can’t post a link.
John
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Post by sumgai on Dec 25, 2007 0:01:28 GMT -5
John, The wannabes, that I can understand...... the Gibbies? I've never seen it, that's for sure. But then again, the only Gibsons I do see are those I work on for customers, they're not my cup of tea. (But you knew that, right? ) I've got a GC nearby (10 minutes, 3 more within 25 more minutes), but as you might guess, they've got this thing about paying employees extra to work on certain holidaze (let alone getting them to work in the first place!), so I'll have to wait a few days before going over there for some hands-on testing. I'm with you on the tone-before-volume thing, but as they say, to each his own. I've got a source or two I might try to tap, and see if the 50's LP's really did get wired as suggested by Specialty. It'll take time though, I might not get an answer for awhile........ sumgai
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servant
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Post by servant on Dec 28, 2007 11:48:13 GMT -5
Hi guys, thanks for the responses. As for my son's bass, he went back to stock wiring per the Rondo link. Sounds like I opened a (good) can of worms with the 50s wiring! ;D Sumgai: MOST Les Pauls (and SGs, maybe 335s and what-have-you) do, indeed, kill all sound when using the center switch position and rolling the volume all the way down on one volume pot. This is the configuration for "slicing." Mick Taylor did this on Jumping Jack Flash, live, in the early 70s (I'm jumping jack flash, it's a gas, gas, gas, Duddle-ahn, na-na-na-na-; duddle-ahn, na-na-na-na - you know where I mean ). "That guy" who played lead for Norman Greenbaum on Spirit in the Sky did this for "that weird sound" before the verses. I have no affiliation nor affinity for specialtyguitars; that's just the first link I could find when I went surfing. The actual diagrams I had seen earlier, with photos of a modern and vintage LP control cavity, was actually at dominocs.com/AshBassGuitar/Gibson50s.html. And I do know that RS Guitarworks wiring kits use the 50s wiring scheme, but they don't necessarily state that online... So - educate me. Why is the 50s wiring so "wrong" to the Gibbies?? I'm experimenting with it right now on my modern (2005?) LP. I like it but wish I could build a test rig where I could quickly switch between the two for an apples to apples comparison. It DOES seem to produce a less muddy tone, overall... Thanks again, guys!
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Post by JohnH on Dec 28, 2007 14:01:26 GMT -5
Hi servant - good response! For the Rondo-wired bass, what do you think of the operation of the controls? do you get a smooth transition as you mix the pups, or reduce volume? - just curious. This 50's wiring 'thing': It comprises putting the tone control (pot in series with cap) after the volume control, wired from volume pot centre lug to ground, rather than before it wired between the vol pot outer lugs as per modern wiring. I'm assuming 50s wiring as in the Specialty diagram that you posted, which I think is the usual way to do it At full volume, there is no electrical difference between the two schemes. They should sound the same at all settings of the tone control. The other settings are harder to explain - If you reduce volume, but keep tone at 10, then at high frequencies, the load on the pickup reduces the more the volume is reduced. Example, lets say you have two 500k pots, and considering high frequencies so the cap is letting all the highs through to the tone pot. At full volume the load on the pup is effectively two 500k in parallel = 250k. If the volume pot is at half resistance, then we have 250k in series with (250k and 500k in parallel) = 417k. This higher resistance, acting with the pickup inductance makes the sound slightly brighter, but only if you have reduced volume with tone at 10. That is the claim for 50's wiring I believe. Heres where it all falls apart (theoretically, if you have it wired up, you can test it and confirm or refute!). If you set reduced volume, and then reduce the tone control: The tone control is now seeing a much higher resistance than it did at full volume, and it cuts much more deeply into the frequency response. You may find that the tone control cuts out everything except the low mids and bass, resulting in mud, or it may just cut out everything - acting like another volume control. Best thing is to try it, so in summary heres the predictions for 50s wiring as compared to modern: full volume, full tone - no difference half volume, full tone - a tad brighter half volume, reduced tone - mud! The greatest differences will likely be with volume pot at 50% resistance, which would be at about 7 on an audio taper pot or 5 if you have linear pots. One more brick to throw at it, when you combine two pickups on an LP: In both schemes, at full volume, the tone controls are not independent, turning tone control one down acts on both pups equally. But with modern wiring, if you reduce both volumes slightly, you can then reduce the treble on one pup independently, hence achieving a mix of say, full tone on the bridge pup mixed with just the bass from the neck. This will not work with 50s wiring, with both pups selected, the tones both act equally badly on both pups. BTW - I don't think 50's wiring is very good. But why not give it a spin, and see if those theoretical predictions are right? cheers John
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