what 's in this old national double 8?

Kris Brown · Post by **Kris Brown** » 17 Aug 2004 8:19 pm

Can anybody help me determine what kind of pot this is in my national? Also, if anybody knows where to get said pot, that would be of great help. I also need to know what kind of capacitor to get. if anybody can help, I am very thankful. The truth is, I don't even know what kind of guitar this is. I just know that it's an old national double 8 and it sounds killer. peace,kb
http://pg.photos.yahoo.com/ph/familysauce@sbcglobal.net/detail?.dir=cf61&.dnm=f10a.jpg&.src=ph http://pg.photos.yahoo.com/ph/familysauce@sbcglobal.net/detail?.dir=cf61&.dnm=2e86.jpg&.src=ph http://pg.photos.yahoo.com/ph/familysauce@sbcglobal.net/detail?.dir=cf61&.dnm=8e41.jpg&.src=ph http://pg.photos.yahoo.com/ph/familysauce@sbcglobal.net/detail?.dir=cf61&.dnm=dd73.jpg&.src=ph

Paul Arntson · Post by **Paul Arntson** » 17 Aug 2004 9:39 pm

Hi Kris
I can't seem to get your photos to come up. It is asking for a login.
Go to this site to learn about identifying pots and date codes: http://www.provide.net/~cfh/pots.html

If it were my project, I would get a 100K a 250K a 500K and a 1Meg and just see which one sounded best with those particular pickups to your taste. Same with capacitors. I would start with a 0.01, 0.022, 0.047 and a 0.1 and see what I liked. You can also parallel and series caps to get even more values. I don't think you can hurt anything just by experimenting with component values.

If you are just looking for an exact replacement, measure across the two outside contacts of a pot to get the resistance. Caps are usually written on it somewhere like 0.01 uF or something. In a guitar, voltage of caps is not critical.
-paul arntson
[This message was edited by Paul Arntson on 17 August 2004 at 10:41 PM.]

Bill Bosler · Post by **Bill Bosler** » 18 Aug 2004 4:23 am

All you can do with any R/C tone circuit is roll off high frequencies. Even if the pot is set to zero resistance, the capacitor will still cut off some of the highs. I always clip the capacitor leads and take the tone control completely out of the circuit. Let your pre-amp tone controls do the work.[This message was edited by Bill Bosler on 18 August 2004 at 05:24 AM.]

Paul Arntson · Post by **Paul Arntson** » 18 Aug 2004 10:10 am

I agree except if you put the capacitor in series you can roll off the lows instead. My epiphone 3-knob does this with separate bass and treble knobs.

Your point about just clipping off the cap is a fair one, too. I didn't even have a volume on my first lap steel.

Another thing I have done on the rare occasion where there is too much treble is use a lower value volume pot (and thereby use the inductance of the pickup) as a treble limiting factor.

-paul

Bill Bosler · Post by **Bill Bosler** » 18 Aug 2004 5:23 pm

You're right, Paul. I should have added SERIES R/C circuit. But series circuits are what you'll find 99% of the time, especially with steel guitars.

Kris Brown · Post by **Kris Brown** » 18 Aug 2004 6:50 pm

Thanks everybody for the advice. What is R/C? I have so much to learn. This is a volume pot, not a tone one. Does this mean that the wire with the capacitor is going to the tone pot? I can't find a schematic, partially because i don't know what kind of steel this is. I am going to follow Paul's advice and get a bunch of various pots and caps and unleash the mad scientist that lurks seedlike within....actually, I'm probably going to try to recreate what was there as much as possible, simply because I love the tone of this instrument. I am sad that my pics don't work. I think that i need a 500k pot. It appears that there are two single coil coil pups both going to this volume pot. it's the master volume for the close neck. there is a master volume, tone, and 3 way switch between the necks also. since they all seem to functioning fine, i'm planning to leave them alone for now. I'll take more advice if anybody's got it, but i am very thankful for all of your input. i look forward to posting more problems! peace,kb

Paul Arntson · Post by **Paul Arntson** » 18 Aug 2004 7:04 pm

Say Bill - you are 100% correct - the only bass cut circuit I've ever seen in a steel is in my epi. Sorry if I was being nit-picky about details.
Kris - R/C that we are bandying about is just electro-geek slang for resistor-capacitor. Since capacitors pass through more high frequencies than low frequencies they use them for tone controls. The tone pot (R) works with the cap (C) to make a cutoff frequency where the frequencies above the cutoff have a harder time getting through. In the dark tone position, the high frequencies just get shorted out more. So you can adjust that freq with the pot, yielding bright or dark tone.

A volume pot interacts somewhat with the tone of the guitar due to the inductive nature of the pickup (it's a big coil). If the overall resistance of the volume pot is too low, the treble notes stay stuck in the pickup and can't get out around the inductance. Within reason, it can be a pleasing effect. I think your starting with a 500K volume pot is a fine idea.

You should be able to find a schematic of something that will work on the seymour duncan pickup site. Just look for one with the same type of switch and number of controls as you have. Post again here if you can't find one and I'm sure one of the many knowledgable (more so than I am) folks here can help you out. I know electronic theory but not much practicality on steels.

best of luck
-paul arntson

John Bechtel · Post by **John Bechtel** » 19 Aug 2004 10:30 pm

I've found a nice workable combination that I use on my Fender T–8 Customs. I use (2) - 250K Audio-Pots and an 0224 cap.

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“Big John” Bechtel
(2)-Fender ’49–’50 T–8 Customs
Fender ’65 Reissue Twin-Reverb Custom™ 15”
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