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Topic: Tone Control not Smooth on 1959 Fender Champ Lap Steel |
David Lindsay
From:
California, USA
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Posted 16 May 2018 12:54 pm |
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I recently purchased a 1959 Fender Champ Lap Steel in great condition, with all original parts. It sounds beautiful but the Tone Control does not change the tone gradually; it is just dark when turned to the left, then at some point it turns instantly bright, when turned to the right. I read all kinds of things on the Internet about different potentiometers (pots), and tapers (linear vs audio). and capacitors (caps), and how different combinations can create smoother fades, etc. I know that smooth tone control is possible, because I’ve seen videos of many people using the Tone Control on old Fender lap steels like a “wah-wah†effect.
The pickup on my Fender lap steel is a single coil pickup. From most of the postings I’ve read, and people I’ve talked to, they all seem to agree that a 250 K pot should be used with a single coil pickup. But I’ve seen the wiring diagram for the 1959 Fender Champ Lap Steel, as well as other brands from that era, and they all use a 1 Meg pot. Does anyone know why that is? Here is the original wiring diagram:
Anyway, the original Tone Control setup on my lap steel was a 1 Meg linear taper pot with a 0.05 mf cap, but as I said, the tone would just go from dark to bright instantly, not smoothly. Here is what I have tried so far…
1) Original: CTS 1 Meg linear taper pot with vintage “Astron†0.05 mf, 200 v capacitor
> Tone control not smooth; only 2 tones - Dark turns instantly to bright.
2) Fender 1 Meg audio taper pot with vintage “Astron†.05 mf, 200 v capacitor
> Tone control still not smooth; only 2 tones - Dark turns instantly to bright.
3) Fender 1 Meg audio taper pot with Sprague 0.022 mf 400 v “orange drop†225P capacitor
> Tone control still not smooth; only 2 tones - Dark turns instantly to bright, but hardly any difference
4) CTS 500 K audio taper pot with Sprague 0.047 mf 100 v “orange drop†225P capacitor
> Tone control still not smooth; 1st third of a turn has no signal, then the last 2/3rds is bright signal with no tone change thereafter.
Since I was getting no change with all these combinations, a friend suggested that maybe the problem was the pickup winding or wiring. The diagram mentioned above showed the pickup rated at 6.65kΩ. When I measured the resistance output with an ohm meter, it showed 6.0kΩ. Since the pickup was still wired to the pots when I measured it, I assume that the reading was close enough to indicate that the pickup was fine.
The last combination that I haven’t tried yet is an Emerson Pro 250 K Audio Taper Pot with a Sprague 0.022 mf 400v ORANGE DROP 225P capacitor (or possibly an 0.015 mf capacitor). I will try that, since most folks seem to recommend a 250 K pot for a single coil pickup. But I still don’t understand why these lap steels (and others from that era) all seemed to come with 1 Meg pots for the Tone Control. Many of the videos I have seen with the player using a smooth Tone Control, were filmed in the ’50s, so I’m sure they were using the original 1 Meg pots. Very strange.
Any comments would be appreciated. I will post my findings after trying out the 250 K pot.
Thanks much! |
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Stephen Cowell
From:
Round Rock, Texas, USA
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Posted 19 May 2018 4:37 am
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Tone pots for Fender were 250K... a 1M gives the effect you're getting. Not sure why your guitar nas a 1M... none of my guitars do, and I own at least seven Fenders.
_________________
New FB Page: Lap Steel Licks And Stuff: https://www.facebook.com/groups/195394851800329 |
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David Lindsay
From:
California, USA
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Posted 19 May 2018 10:18 am
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| Thanks, Stephen! |
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Joe Major
From:
Florida, USA
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Posted 19 May 2018 11:56 am
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| if you're used to playing with the volume on full, try rolling it back a little. The volume and tone aren't completely independent in most cases. Lowering the volume can dampen the tone. My Champ acts like yours, but I can vary the tone using both controls together. |
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David Lindsay
From:
California, USA
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Posted 23 May 2018 1:17 pm
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Thanks Joe,
You are right; when I lower the volume, the tone control sweep is more obvious. Anyway, I tried a 250 K pot, as recommended by a well-known guitar repair guy in L.A. Here is what I found...
- Emerson Pro 250 K Audio Taper Pot with Sprague 0.015uf 100v ORANGE DROP 225P Polyester Film type capacitor.
> Tone control still had only 2 tones, but the difference was BARELY perceptible. If the volume control was turned down a bit, the tone sweep was a bit more obvious and smoother.
HERE IS WHAT I SETTLED ON: Emerson Pro 250 K Audio Taper Pot with Sprague 0.047uf 100v ORANGE DROP 225P Polyester Film type capacitor.
> Tone control sweep has a longer range and is smoother. When rotated quickly, the tone control creates the "wah-wah" effect that I heard on some lap steel videos. Also sounds as if the larger capacitor slightly took off some of the highs from the top end of the sound.
So basically, by choosing the 0.047uf capacitor, I stayed close to the original 0.05uf capacitor, but changed the original 1 Meg Linear Taper pot to a 250 K Audio Taper pot. That gave me the smooth, long range tone control that I was seeking, rather than the original tone control setup, which was just dark instantly changing to bright.
Thanks for your input, guys! |
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Frans van Winkel
From:
Netherlands
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Posted 2 Nov 2020 5:14 am
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Hi David, I just read your story concerning your Fender Champ and I also have some problems with the pot.-meters.
Tonecontrol seems not divided over the whole pot, so it's there after turning the knob a bit, let's say from 0 to 3, and from 3 to 10 there's no hearable difference.
Also the volumecontrol is not what I expect to hear.
Both pots are cleaned by myself.
This is my Champ:
https://bb.steelguitarforum.com/viewtopic.php?t=362731&sid=a1dff86101081c633400533c5dd3f9fb
Do you see items that could/must be changed or do you have other remarks?
Glad to hear from you,
Kindly regards,
Frans |
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Frans van Winkel
From:
Netherlands
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Posted 12 Nov 2020 6:15 am Tonecontrol not smooth
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I'm a little bit dissapointed 'bout nobody reacting on my question(s).
Never the les: steel them!
Frans |
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Mike Auman
From:
North Texas, USA
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Posted 12 Nov 2020 7:56 am
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Frans, in your other post you mentioned your Volume pot was 250kA (audio taper) and your Tone pot was 1MB (1 meg linear taper). If you'll do what David did and replace your tone pot with a 250k audio taper, you should get the same result, a more usable tone knob. You can fine-tune the depth of the treble cut with the capacitor value. 0.047 uF is traditional but you might try something less for a more subtle change, maybe between 0.01 and 0.033 uF. Mike
_________________
Long-time guitar player, now wrestling with lap steel. |
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Frans van Winkel
From:
Netherlands
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Posted 24 Nov 2020 3:17 am
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| Thanx Mike! |
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