Bridging a resistor on volume pedals

Doug Jones · From: Oregon & Florida

In an attempt to get crisper lows, I've sought advice from some folks. I've tried thinner sounding pickups, matchbox, etc. Just recently I received a recommendation to place a 500K resistor on the hot and ground either at the output jack of the steel or at the input of the volume pedal. I got a 470K 1/2 Watt resistor and put it on the inbound hot and ground of the 500K pot in my volume pedal. It thinned it out (both highs and lows) and seemed to increase the volume. It also seemed to tighten up the overall tone. Any comments from you tech-wiz-bang folks?

Bill Crook · From: Goodlettsville, TN , Spending my kid's inheritance

Doug....

As an Electronic tech,I think anytime you place a resistance or capactiance in front of the amp,you only decrease the output of the P/U. Now,as most of us know,we desire the max signal from the instrument. Therefore,we can EQ it or trim to fit our needs at the amp. To reduce the primary signal from the P/U isn't such a bright idea.

O.K..... This info is for the "passive" V/C pedals only !!! Any "powered" pedal such as the "Hilton" or "Goodrich" pedal has pre-amp circuits build-in. (In this case,you don't need to worry about this problem) I am a great believer in the "Myrick" mode of a passive pedal. This modification attempts to present the max signal to the amp at any volumne level.

Jack Stoner · From: Kansas City, MO

Placing a resister across the input/output effectively decreases the resistance of the volume control pot. The sum of two resistors in parallel that are the same value is 1/2 the resistance amount of one and in this case by placing the 470K resistor in Parallel with the 500K (when it is at the max resistance point in it's travel) you have reduced the overall resistance to approximately half.

The "Myrick" mod to the volume pedal is a similar mod but uses another 500K volume control pot.

The volume pedal should not have that much affect on your tone. It can have some affect but not what you are looking for.

I use Lawrence 710 pickups on my Franklin, a stock Goodrich 120 volume pedal (500K pot model) and in conjunction with how I set the EQ on my Nashville 400 I can get the lower strings on my C6th neck to be "crisp". I don't get the treble my Telecaster is capable of but then I don't want that much treble on my steel.

I think the answer to what you want is more in the amp than in the guitar or volume pedal. One other thing that will have a major affect on tone or frequency response is the cords. You have to have decent cords or everything else you do won't count. I use to use Belden 8410 cable, which is a high quality shielded audio cable, for my cords and I thought it worked good until I bought some George L's cables. It took me 10 minutes with the George L's cables and the Belden was history.

Jack Stoner · From: Kansas City, MO

I would think the Lawrence IQ 1200 unit would do the opposite of what he wants. Bill told me, at St Louis 2 years ago, that it wasn't for someone who played mostly "country" but more for someone who wanted a jazz or pop sound.

Keith Hilton · From: 248 Laurel Road Ozark, Missouri 65721

Doug, I don't see how the resistor, wired as you described, would help the frequency response of your pickup. I've tried many combinations of resistors and capacitors across a pot. The keys to good sound is making sure the pickup sees high impedance and low capacitance. Like Jack told you, hookup cords make a big difference when using a pot pedal.

David Rich · From: Lexington, KY

This should make the pedal less bright and less volume. Your result seems contrary to what I would have thought.

Donny Hinson · From: Glen Burnie, Md. U.S.A.

I need to know what kind of amp you're using. The amp can do far more, tonally, than the passive circuitry you describe.

Doug Jones · From: Oregon & Florida

Thanks for all your responses. I A/B'd both of my Zum pedals which have 500K pots; one with the resistor and the other without. There was a definate tone loss; kind of a washed out sound if there's such a description. For the record, I use Carol C-1300 oxygen-free audio cable with Swithcraft plugs. My stage rig is a '92 Lashley, a modified Goodrich 4a Matchbox, Evans preamp, Lexicon Alex, Ibanez DD-1000, Korg DTR-1 and 2 Evans FET-500LVs (power sections only). I'm going back to my regular vol. pedal set up.

Doug Jones · From: Oregon & Florida

Hi Jack. Thanks for your input and info. OK to close thread. - DJ -

Terry Downs · From: Wylie, TX US

I agree with the responses. The lowering of the effective pot impedance will only reduce highs and amplitude unless of course you have an active setup.

HOWEVER, the placement of a resistor across a pot will change its taper. It adds a hyperbolic term to the taper. In fact, if you are out of town and are in a pinch for a volume pot and all you can find is like a 1 Megohm linear, you can put another 1 Megohn or 500K fixed resistor across it and approximate a audio taper pot. Of course this is not optimial, but it brings it closer to a base 10 logarithmic response. I have some graps in Excel that shows that if you would like to see them.

An audio taper pot is not the same as a logarithmic pot. The audio taper pot is a logarithmic taper with the asymptotic extents rounded off.

Just thought I'd throw that in. I was curious a long time ago about a fixed resistor across a pot, so I graphed it to see.

Good post.

------------------
Terry Downs
http://nightshift.net
terry@nightshift.net

Jack Stoner · From: Kansas City, MO

I've never heard of the Carol cables you mention. As an electronics tech, the "oxygen free" doesn't do anything for me. It's the electrical specifications that really count, such as capacitance resistance per foot, etc.

Keith Hilton · From: 248 Laurel Road Ozark, Missouri 65721

OK Jack, if the Oxygen Free doesn't do anything for you, Bobbe Seymour has "GOLD" connection cords. Bobbe Seymour was telling me about the recording studio he had, and it had solid GOLD hookup cords. Think of it Jack, solid GOLD, the sound would just have to be better! I am smiling Jack!

[This message was edited by Keith Hilton on 14 April 2001 at 08:45 PM.]

Bobbe Seymour · From: Hendersonville TN USA, R.I.P.

Whats funny is that the George L cords sound as good as the gold did and cost a lot less!
Bobbe

Donny Hinson · From: Glen Burnie, Md. U.S.A.

Doug, I don't know what kind of "sound" you're looking for, but it sounds like you've got enough "stuff" between your axe and the amp to confuse even an electron!

Do you really need all that "stuff" to sound good?

If I had to guess, I'd say that all that "stuff" might be part of the problem you're complaining about...just a thought.

Keith Hilton · From: 248 Laurel Road Ozark, Missouri 65721

Now Bobbe, which would make a "singer" feel better? Singing over pure gold, or "non gold" connecting cords? Therefore, we better leave the pure gold hookup cords in the studio for the singers, and hook up our steels with the George L cords.

Jack Stoner · From: Kansas City, MO

Although I personally consider gold connectors for instrument cables to be a marketing pitch, gold is an excellent conductor. Plug in printed circuit boards with printed edge connectors which are usually plugged in, many for years, are a prime application of gold connectors as they do not oxidize or exhibit flakey connections as easy as other metal compounds including silver.

For guitar cords or patch cords that are being plugged in and unplugged frequently, good grade standard connectors such as the Switchcraft 280 1/4" plug, George L's plugs, more than suffice. The connection resistance on this type of plug is negligible.

Keith Hilton · From: 248 Laurel Road Ozark, Missouri 65721

Ok, I was doing a little joking,kidding and having a little fun. Bobbe knows me enough to know I like to have fun.

Bill Crook · From: Goodlettsville, TN , Spending my kid's inheritance

Mark Herrick · From: Bakersfield, CA

I recently received a mailer from George L's announcing the re-issue of "Vintage Red Cables" and unplated brass plugs.

Anyone have any experience with these? (Not that I'm rushing out to replace what I already have!)

Jack Stoner · From: Kansas City, MO

Mark, I got that mailer too.

I rushed right out and ordered the red cables - NOT

Another marketing ploy. I guess red colored cables are better, just like black formica steels are the best sound.

Donny Hinson · From: Glen Burnie, Md. U.S.A.

Unplated brass plugs will oxidize in only a few weeks under the right conditions. It's no big deal to buff them up with steel wool or Scotchbrite, but why bother? Good nickel plated connectors are far more trouble-free.

Blake Hawkins · From: Florida

Donny is right on the brass audio plugs.
Over 45 years of making my living in broadcast facilities and recording studios,
I've handled more audio patches and plugs than I can count.
Professional audio patch panels use unplated brass plugs. In order to keep the noise down they need to be cleaned on a regular basis.
The problem wasn't too bad with 1/4" phone
patch plugs, but when the industry started going to the smaller "tiny-jacks" which had much less contact area, the required cleaning interval was quite a bit shorter.

I did work with an audiophile engineer who maintained that he could tell the difference in sound between gold, silver, and cadmium plated connectors. He did not like the sound of the gold ones. However, he never did demonstrate this ability to me.
One time when we ran short, I put some gold ones in the system. He didn't know they were there until one of the other engineers told him.

Jack Stoner · From: Kansas City, MO

I was a Tech Controller in the Air Force. Patch panels was one of the things Tech Controllers used to test and substitue teletypes and other comm equipment. The military PL55 and PJ068 and later the smaller plugs Blake referred to were on a regular monthly PM schedule for cleaning. We used steel wool and brasso to keep them clean.

The telephone companies used the brass plugs in their manual patch panels for years. They still use them today in their analog test equipment.

Wilfred Luttrell · From: DeRidder, LA, USA

I simply made my pedal hotter by altering the string pull on the pot. Of course my pedal will not "cut off", but then I still have the swell I need and the resistance does not eat up the signal sent to the amp.

Forum Index > Electronics	Goto page 1, 2 Next	Next oldest topic :: Next newest topic