Who is using the pre eq patch for their volume pedals

Quentin Hickey · From: Nova Scotia, Canada

Just for kicks the other day I thought I would try running my goodrich 120 through the pre eq patch of my 112 and my 1000.

I found the results odd, Alot of the higs and mids went out the door and I found it a little muddy sounding, less sparkle. I tried different length cables and diferent make cable but it turned tout the same.

I thought that this was a buffer circuit so that you didnt get a tone suck becaseu of line impedance in the circuit.
I had to crank my hig and precense up alot and and when I got those levels up to where I like it, I found that there was still not present.

When you run your volume pedal straight from guitar to amp is it possible that you might be loading up your pickup a little. Prbably this is what I am not hearing is a little loading up, not sure but who out there uses this patch for their volume pedal?? What are some pro's and con's Mr. Green

Scott Duckworth · From: Etowah, TN Western Foothills of the Smokies

I use the pre-eq setup, but also use a Li'l Izzy out of the guitar.

Guitar to Li'l Izzy, to amp input, pre-eq out to volume ped, to Zoom MS-50G effects, to pre-eq in.
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Quentin Hickey · From: Nova Scotia, Canada

Scott.
Do you find that you get the same results with the guitar to volume pedal to amp as using the little izzy to amp and volume pre eq patch?

I heard good things about the little izzy.

To me it just almost seems like your subtracting something adding it rather than just going direct and not subtracting it in the first place.
For those of you who have tried the pre patch you probably know what I am talking about.

chris ivey · From: california (deceased)

i just prefer izzy--vp--amp. i personally like my delay in front of the vp. good strong signal and simple set up.
i never liked putting my effects through an effects loop.

Tom Gorr · From: Three Hills, Alberta

I dont understand how it could be practically useful....you run a ten or fifteen foot cable to the amp...back to the fp...and back to the amp....

Forget about it...better to use a preamp buffer right at the steel.

If Peavey sold the amps as head and cabs...then the head would be arms length away. Then it would have practical value..maybe. Its an op amp buffer.

Scott Duckworth · From: Etowah, TN Western Foothills of the Smokies

Let me answer some questions / thoughts with this.
I do think the pre-eq setup sounds cleaner to me.
My Nashville 112 is "split" with the electronics sitting right beside me in a case. My cables (GeoLs) are each three feet long.

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Alvin Douglas · From: Prince Edward Island

I am using a double 1/4" cable for my volume pedal.

http://www.musiciansfriend.com/accessories/live-wire-1-4--1-4-pro-dual-patch-cable?rNtt=live wire dual cable&index=4

I think there is less effect on tone than when I connect it between the guitar and the amp I/p. Somehow got it into my head that this connection would use the pedal to control the fwd. gain of the pre amp. I did find that the pedal has a little less effect on the output volume. When it's at minimum, I still get some signal to the amp. Full volume appears to be normal. No idea how right I am about the theory of this but I do like the sound better using this connection.
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Brad Sarno · From: St. Louis, MO USA

This is ALL about the "impedance" factor. Impedance has a dramatic effect on the tonal response of the pickup itself. That's why a 500k pot pedal sounds so different than say a Hilton pedal with a 1Meg input impedance. The Hilton is naturally much, much brighter. If your ears are used to the 500k pot pedal tone and then you switch to plugging directly into the Peavey's input and then placing the VP in the buffered loop, then your pickup now sees the input impedance of the Peavey, which is quite a bit lower than the 500k pot pedal. This is why you get a mellower, darker tone. Peavey calculated this impedance precisely for this reason so you could warm up, mellow-out your pickup's tonal response.

The Peavey's input impedance is 220kOhm. Pot pedals are 500kOhm. Hilton is 1MegOhm. I find that many players that have full variable control over impedance loading often settle on a value below 500k and above 100k. 180k to 330k is a popular range for many players. This control is especially important with transistor guitar rigs where midrange and treble harshness is a real issue to contend with.

This powerful effect that pickup load impedance has on the pickup tone is why for all these years I've offered "variable impedance" or "Vari-Z" as I call it on my FreeLoader, Black Box, Tonic, and Revelation preamp. There's such a wide range of tone control right there at the pickup loading that it seems natural to want full control over it. Even Telonics decided to add the variable impedance to their feature set on their VP and preamps, although via screwdriver-trimpot only.

Brad

Tony Glassman · From: The Great Northwest

Brad,

Thank you for the excellent explanation

Mike Brown · From: Meridian, Mississippi USA

To determine if your pot volume pedal is causing the results that you hear, simply patch a good quality shielded signal cable between the PRE EQ SEND and the PRE EQ RETURN jacks(not using a volume pedal). You should get the same signal level tone as when using your volume pedal. If there is a tone/level change when plugging in your pedal, then the difference is in the pedal and not the amplifier.

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

Brad, let me update you. The input impedance of the IC pre-amp--"CHIP"-- I use is 1M ohms. But 1M ohms is not the actual impedance the guitar pickup sees. Input impedance is not the only thing that determines tone of a pre-amp IC. The tone of a pre-amp IC is most determined by component values of several capacitors that make the non inverting op-amp work. Somewhere around 18 yeas ago, in developing the Hilton pedal, Doug Jernigan and I tried 60 different pre-amp tone arrangements. Doug tested them each time he played on the Grand Old Opry with Jack Green. Developing the tone of a pre-amp is difficult, and takes a lot of trial and error. Since Doug and I finalized the pre-amp tone, the Hilton pedal has had this same pre-amp tone for the last 18 years. It has worked for the many great players who used it. For example players like: Herby Wallace,Hal Rugg, and John Hughey to name a few of the thousands. John used my pedal on all those famous Vince Gill recordings you love. No one could argue with "THAT" tone. Now, back to the impedance thing: Even though the input of my pre-amp IC is 1M ohms, that does not determine the actual input inpedance the pickup sees. You ask why? Because: from the pickup input, I use a 249K resistor to a .02uf capacitor to ground, before the signal ever gets to the 10K resistor and .1uf capacitor that feeds the input of the pre-amp IC. Then there is a 39pf protective capacitor to ground connected to the input, that prevents radio signals from entering. If you take a OHM meter and measure from the input pin of the pre-amp IC to ground, you get somewhere around 500 ohms. Brad,I respect your ability and talent with electronics---and that is why I thought I needed to update your information. I consider you a friend. I also highly respect Mike Brown, he has been helping people for many,many,many years--and I consider him a friend. Very Happy

Brad Sarno · From: St. Louis, MO USA

Keith,

thanks for that update. I had assumed all this time that your pedal had a 1Meg input impedance and that was what accounted for it's brighter tone quality. I sure hope my comparison didn't come across as a complaint about your pedal. I still own and enjoy mine that I've had for over 14 years now, and clearly we've all heard these tone monsters put your pedal to great use.

Your description of the input section really does completely change my understanding of what's happening there, and I appreciate the correction and information. And as I see it now, with the 249K resistor with a path to ground thru the .02uF cap, that kind of puts it right in that range where I've observed so many people liking to dial in their pickup load impedance when given control over it.

Thanks for the kind and informative reply my friend.

Brad

Jim Pitman · From: Waterbury Ctr. VT 05677 USA

If you have a flat freq response premap then yes, the LR formed by the pickup and the input Z dominate the tone. If the pre-amp has fixed or variable tone shaping than one can overcome it.
Both Brad and Keith make good points.
Note a steel guitar pickup impedance (Z) is roughly 3X the impedance of a regular 6 string electric guitar pickup. I've often thought the input Z is too low for pedal steel on many solid state amps including Peavey. I've owned three and on all I have raised the Z by changing the input resistor (not always that simple) to a 470K. - quite a dramatic change.
Typical tube amps like fender input Z is 1Meg. That may be one of the reasons so many steelers are switching to tube amps.

Bob Lawrence · From: Beaver Bank, Nova Scotia, Canada

re: I've often thought the input Z is too low for pedal steel on many solid state amps

Yes, I started to ask the same question about input resistors after I studied tube amp design. It would be a interesting project to take all popular steel guitar pickups, amps etc and calculate the input impedance for each setup.

chris ivey · From: california (deceased)

these last two posts make me wonder how emmons and other top pros sound so good through a backline of pv amps. i guess you guys are just more sensitive and have a more discerning ear.

Stephen Cowell · From: Round Rock, Texas, USA

If you have a buffer, especially an adjustable impedance buffer, this problem goes away.
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Steven Paris · From: Los Angeles

There is something I am not seeing here---someone please explain. How does an ohm meter measure only 500 ohms to ground on the input of a non-inverting IC that is otherwise coupled to ground by capacitors?
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