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Topic: Gibson Console Grand 8-string |
Terry Egan
From:
Missouri, USA
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Posted 19 Jul 2010 7:49 am |
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I was fortunate to purchase a 1955 Gibson Console Grand in excellent condition over the weekend. I'm hoping that someone here has a wiring schematic for the volume and tone controls. One of the pots is shot and needs replacement, and the caps might need replacing too. But, I can't really figure out what the three pots do. There seems to be single volume (top) and tone (middle) controls. If this is the case, then what is the function of the third (bottom) control (this is the one that is very stiff on my steel and presumably broken)?
Also, does anyone know where I can buy appropriate replacements?
Thanks in advance,
Terry
Last edited by Terry Egan on 19 Jul 2010 10:46 am; edited 1 time in total |
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Erv Niehaus
From:
Litchfield, MN, USA
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Posted 19 Jul 2010 10:41 am
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Two of the knobs are for tone.
Sort of treble and bass controls. |
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Terry Egan
From:
Missouri, USA
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Posted 19 Jul 2010 2:32 pm serial numbers
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Thanks Erv,
That makes sense. Another question. I know the console originally sold in 1955 (I bought it from the original owner). Here are the only numbers on the console.
DH - initialed in control cavity
DS 3-138 written in ball point pen on the back of the console under the tuning pegs. 138 is also written under the pickups.
Any idea what these numbers mean?
I have to say that it is a fantastic instrument, with tons of sustain. And, it was made of some very attractive pieces of flamed maple that are readily apparent in the natural (CGN) finish.
Terry
Terry |
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Steve Ahola
From:
Concord, California
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Posted 19 Jul 2010 5:01 pm Re: Gibson Console Grand 8-string
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| Terry Egan wrote: |
| I was fortunate to purchase a 1955 Gibson Console Grand in excellent condition over the weekend. I'm hoping that someone here has a wiring schematic for the volume and tone controls. One of the pots is shot and needs replacement, and the caps might need replacing too. But, I can't really figure out what the three pots do. There seems to be single volume (top) and tone (middle) controls. If this is the case, then what is the function of the third (bottom) control (this is the one that is very stiff on my steel and presumably broken)? |
Terry:
I analyzed the control wiring of my 194x Gibson Century which is evidently the same as the Console Grande and posted my findings here and at the Music-Electronics forum (they have a forum for pickup makers with lots of posts from winders like Jason Lollar and other gurus).
I need to get my scanner working so that I can post a diagram but it is very simple to explain verbally. Or maybe not... 
All 3 pots are 500K audio pots with what appears to be a 20% taper (most of the modern pots use a 10% taper). The hot lead from the pickup is connected to the outside "hot" terminal of the volume pot (like most guitars). The wiper of the volume pot has one lead going to the wiper of the middle tone control (which is wired normally with a 0.02uF cap) and one lead going to the "cold" outside terminal of the bottom tone control. The wiper of the bottom tone control is connected to the output jack and has a 0.001uF cap going to the "cold" outside terminal.
The caps are of the old paper and oil type which to my ears sound better than modern caps so hopefully yours are still okay.
A quick synopsis of the circuit: the volume control is fairly normal, but with the lead to the middle tone control coming from the wiper and not the outside "hot" terminal. Gibson calls this their Memphis circuit; Lew Collins at the SD forum called it "50's" wiring long before Gibson started using it again. IMO I think it gives you a smoother control over the tone as you adjust the volume and tone pots. The wiper from the volume control goes to bottom tone control rather than to the output jack (as in most guitars with a single volume pot).
The middle tone control is like 99% of the single knob tone controls in guitars. It is called a "treble cut" or "treble bleed" tone control because it routs some of the high frequencies to ground through the tone cap. It is wired as usual with the tap from the volume control connected to the wiper and a cap from the outside "cold" terminal connected to ground.
The bottom tone control is called a "treble bypass" control because it will route some of the signal through the 0.001uF cap which will pass more of the high frequencies than the lower frequencies. One interesting twist on this design is that being connected to the "hot" outside terminal and the wiper we get a reverse audio taper. (The "treble bypass" tone control design was used in the mid-70's Ibanez Howard Roberts model guitar, but it was evidently connected to the normal audio taper of the pot rather than the reverse audio taper and may have used a larger cap- the drawings I have seen do not include the values.)
By using a small cap like 0.001uF the effect of the treble bypass control is not overwhelming; a larger value like 0.02uF would exaggerate the bass cut. In the Gibson design the treble bypass control cuts the mids a bit as you turn it down from 10; until I figured out the design I had thought that it was a mid-cut control which can clean up the muddiness of a humbucker.
I have heard that I lot of people have disconnected the bottom "treble bypass" tone control but I think that is unnecessary since it really is out of the circuit when set to 10 (assuming that there is no problem with the pot).
Speaking of pots, there is a quick fix that will often works on old pots which are hard to turn: put few drops of a light oil directly on the bushing of the control shaft. Do not use WD40; I would recommend something like Singer Sewing Machine oil.
That will sometimes help if you hear a scratchiness when you rotate the pot. However, it is often necessary to clean and condition the pot. The old pots I have seen are completely enclosed unlike modern pots which makes it trickier to clean and condition the resistive path. There will often be 4 tabs which hold the back of the pot on; bend these very carefully so that you can remove the back at least a little bit. Gibson will make that harder to do by soldering the ground terminals of their pots to the back of the case rather than running a separate wire. However, for the treble bypass control there is no terminal soldered to the case.
There are only two contact cleaners that I will use on anything of value and they are both made by Caig. To clean up old pots and switches, use DeOxit which is the red can. Once you have cleaned the contacts you can then spray them with ProGold which is a conditioner which will make the pots and switches work smoothly for a long time. I will usually spray ProGold on any new pots I use as well as on the pots on any new guitar or other device that I get as a preventive maintenance measure. (It is a real drag to wire something up only to find that the new pots are scratchy.)
I guess one picture is worth a thousand words... (I did attach a photo of the controls on a 1947 UltraTone.)
HTH
Steve Ahola
www.blueguitar.org
P.S. I would guess that "DH" was the person who assembled the guitar or did the final check out, and that "138" had to do with the serial number. But that is just a guess.
CORRECTION! I just took the controls apart to clean and condition the pots and discovered that the pot tapers are reverse audio. Now this is for a 1947 model so I am not sure if that would apply to the later models.
One other minor point: the middle (treble cut) tone control is connected to the volume pot via the 0.02uF capacitor, and the "cold" outside terminal is soldered directly to ground. I consider that to be the best way to wire up a tone control in any guitar if you can swing it because it can reduce the noise picked up by unshielded wires in the control compartment. Only the length of the capacitor leg connected to the volume pot would be susceptible to hum and other noises. I think that the mfg's would rather not wire it up that way because the capacitor legs are more easily broken than regular wire. Like if a pot is loose and rotates around- they would rather replace a wire than the capacitor.
More observations and suggestions regarding the circa 1947 pots as shown in the picture. You need to put the nut on the pot before removing the back (the nut will hold a metal piece which would otherwise fall off).
The middle tone pot control had an unusual problem: it would be a little rough and jumpy turning the control clockwise but completely smooth when turning the control counter clockwise. There was a tiny piece of debris on one side of the wiper, but removing that did not solve the problem. Hmmm... a real head scratcher! I tried more oil on the pot shaft and bushing but to no avail. Closer inspection revealed that there was a small spring at the bushing which keeps a little bit of tension on the control; over time the ends of the spring digging into the brass bushing will some debris which will cause the control to turn a little rough. I used a sewing needle to persuade clear out the debris and the treble bleed control lived happily ever after...
One trick for removing the 1947 knobs- these are the tall ones recessed into the body so there is nothing to grab on to. I used my Vise Grips pliers to hold a loop of solid 22GA wire which I put under the knob and pulled straight up. Voila! Only the third knob went flying and it landed under a table behind a speaker. It would have been a real hassle for me to retrieve it at that time so I put it off for a few weeks until I actually needed it. Guess what? It was nowhere to be found.  Those tall gold knobs are probably worth more than the rest of the lap steel so I was kinda bummed out thinking that it might have bounced around and ended up landing in something that I put in the garbage (I am in the middle of Spring Cleaning which is a bit late... for Spring 2004!  ) It turns out that it landed inside the open back speaker. Whew!
_________________
www.blueguitar.org
Recordings on electric guitar:
http://www.box.net/blue-diamonds
http://www.box.net/the-culprits
Last edited by Steve Ahola on 20 Jul 2010 7:10 pm; edited 2 times in total |
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Terry Egan
From:
Missouri, USA
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Posted 20 Jul 2010 6:22 am
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Thanks Steve,
That pretty much covers everything I need to know.
Terry Egan |
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Steve Ahola
From:
Concord, California
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Posted 20 Jul 2010 6:21 pm
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| Terry Egan wrote: |
Thanks Steve,
That pretty much covers everything I need to know. |
Terry:
Glad to hear that you could figure the wiring out from my ramblings!
I added this note to my original post on this thread:
CORRECTION! I just took the controls apart to clean and condition the pots and discovered that the pot tapers are reverse audio. Now this is for a 1947 model so I am not sure if that would apply to the later models.
One other minor point: the middle (treble cut) tone control is connected to the volume pot via the 0.02uF capacitor, and the "cold" outside terminal is soldered directly to ground. I consider that to be the best way to wire up a tone control in any guitar if you can swing it because it can reduce the noise picked up by unshielded wires in the control compartment. Only the length of the capacitor leg connected to the volume pot would be susceptible to hum and other noises. I think that the mfg's would rather not wire it up that way because the capacitor legs are more easily broken than regular wire. Like if a pot is loose and rotates around- they would rather replace a wire than the capacitor.
More observations and suggestions regarding the circa 1947 pots as shown in the picture. You need to put the nut on the pot before removing the back (the nut will hold a metal piece which would otherwise fall off).
The middle tone pot control had an unusual problem: it would be a little rough and jumpy turning the control clockwise but completely smooth when turning the control counter clockwise. There was a tiny piece of debris on one side of the wiper, but removing that did not solve the problem. Hmmm... a real head scratcher! I tried more oil on the pot shaft and bushing but to no avail. Closer inspection revealed that there was a small spring at the bushing which keeps a little bit of tension on the control; over time the ends of the spring digging into the brass bushing will some debris which will cause the control to turn a little rough. I used a sewing needle to persuade clear out the debris and the treble bleed control lived happily ever after...
One trick for removing the 1947 knobs- these are the tall ones recessed into the body so there is nothing to grab on to. I used my Vise Grips pliers to hold a loop of solid 22GA wire which I put under the knob and pulled straight up. Voila! Only the third knob went flying and it landed under a table behind a speaker. It would have been a real hassle for me to retrieve it at that time so I put it off for a few weeks until I actually needed it. Guess what? It was nowhere to be found. Those tall gold knobs are probably worth more than the rest of the lap steel so I was kinda bummed out thinking that it might have bounced around and ended up landing in something that I put in the garbage (I am in the middle of Spring Cleaning which is a bit late... for Spring 2004! ) It turns out that it landed inside the open back speaker. Whew!
P.S. So how is that Console Grande working for you? I think that is one of the nicest double neck console steels around and would love to add one to my arsenal someday! If you ever need a pickup for it, Jason Lollar has a replacement on his site that sounds really great on the MP3 sample. I didn't realize this but he has played lap steel for many years which I think gives him an edge over the other boutique winders who make steel guitar pickups more as an afterthought. Not to mention the fact that his book on making pickups published in the 90's is what got most of the boutique winders started.
_________________
www.blueguitar.org
Recordings on electric guitar:
http://www.box.net/blue-diamonds
http://www.box.net/the-culprits |
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Eric Andersen
From:
Iowa, USA
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Posted 21 Jul 2010 7:05 pm
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| Try http://singlecoil.com it's an excellent website for vintage parts and information |
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