Trying to get the hisss out of my preamp but still keep the crunch....

My Marshal JMP-1 preamp has lots of hiss which comes out too loud on live gigs when I go thru the PA system....since I want a good reverb/delay effect, I'm buying a Lexicon MX200 ...this unit also has a de-esser feature...my question is where would one connect it up....thru the effects loop or out the mains right into my power amp...

and will the de-esser clean up the hiss noise?

thanks for any advice

I don't think the de-esser will clean up the hiss but I can not say this for sure.

If you could get a better signal to noise ratio then maybe that will help. By that I mean, make sure the signal from your guitar is as hot as it can be while still giving you the sound you want. That way you may be able to turn the whole thing down (which will turn down the hiss) while still having enough level from the guitar.

I'm guessing this is for passages where you are not playing in a song or between songs etc? I mean surely you are not hearing the hiss while you are playing....maybe check out the Signal to Noise dealio as onelife said ....gain staging.

Why not just go for a noise gate? Something like a Rocktron Hush Super C or some other brand. I just wonder if the De-Esser will mess with your signal, taking the unwanted hiss out but also removing some aspect of the signal....perhaps textural stuff..string squeak, cool pick artifacts etc....different kinds of things in a similar freq range to the hiss, stuff that you don't want to attenuate. How it dips in and out as it is killing the freq's you have selected might also sound unnatural. Dunno, never used one on an amp.

Too bad they don't make a hardware version of Cooledit's noise reduction plug...

I get the Lexicon on wednesday...I'll keep you posted...if it gets the hisss out, might be a game changer for everyone.

Since a de-esser works on dynamic material, I would be very surprised if it got rid of any hiss.

I've found the best way to reduce the amount of hiss you get is to change your valves. The JMP is a valve preamp, right? Also, you can get noise reduction pedals - I think ISP do one. Lots of the high gain players on the Amps forum and on places like rig talk rate them highly, because they are noise reduction rather than simple gates, as far as I know.

But yeah, try new valves - in the time I've had my ac30 (different beast, I know), it's been everything from annoyingly hissy to totally silent, like you have to put your ear to the speaker to hear anything at all! And it's just down to the tubes.

The only thing that will help is a hush box, but what has me concerned is how exactly is the Preamp connected to the PA.

Guitar preamps have line outputs and are designed to drive a power amp. Running it directly through a PA channel without proper

impediance matching will give you too much hiss because the signal is being over amplified. Uou need about 3db of attenuation

if you're going to plug into a high impediance 1/4" input and you "definately" shouldnt be connecting the XLR output of a guitar

preamp into a low impediance mic channel input.

The XLR outputs on a guitar preamp are all Line Level outputs. You cannot plug them into a Mic input.

The hiss and background noise would be way too high and the signal way too high for a mic input as well.

If this is your only connection option you definately need an attenuator like this.

http://www.amazon.com/Shure-A15LA-Adapter-Attenuate-Impedance/dp/B0006NMSXS

Personally I'd only use a Speaker Emulated Line output for direct connection for natureal sound quality or mic the amp when running through a PA.

I think you're chasing a dream here. The way that you get "crunch" out of a preamp is to have gains and levels such that the preamp becomes non-linear at high levels. There are two ways to do this. One is to play louder so the input signal is at a higher level, the other is to increase the gain of the amplifier so that a lower level signal is capable of driving it into non-linearity (distortion).

Unfortunately, with all but the best circuit designs (think $1,000/channel mic preamps) hiss increases with gain. The reason is that the natural electronic noise in the circuit is being amplified along with the desired (guitar) signal. This is common with guitar accessories, even amplifiers, and it's largely a consequence of making the preamp input compatible with nearly all guitar pickups, which have a high source impedance and moderate output level.

You can probably do a better job of making the hiss less noticeable by reducing the treble than any other method other than a noise gate, which will give you the side effect of the hiss starting and stopping with your playing, which I find to be more annoying than having the hiss there all the time. There's very little above about 4 kHz coming out of a guitar amplifier speaker, so if the treble control on your amplifier works in the right way, you won't hurt the guitar sound by cutting treble.

A de-esser is a filter that works over a fairly narrow band of frequencies and becomes active when the level is above an adjustable threshold. This, if it had any effect on the sound of your guitar at all, would serve to cut that frequency range when you're playing loud, which is when the hiss is least noticeable.

Maybe all the guitar gadget experts here can come up with an adjustable low-pass filter to plug in between your preamp and amplifier (or DAW if ths is for recording - I don't remember if you said one way or the other), one that would give you a sharper cut-off than the tone control on an amplifier that's meant for shaping tone rather than fixing problems.

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Ther hiss coming through a PA shouldnt be an issue to begin with.

First off, the highest frequencies a guitar can produce are in the 5~6K region.

If you're getting hiss, dollars for donuts you have the High frequency cranked on the PA which is senceless.

Theres no musical content there so no need to crank those frequencies, and even if there was musical content there,

you wouldnt push it to interfere with the vocals. The exception might be an acoustic guitar.

Most PA systems only push 13K hz if your luckey. A guitar shouldnt come anywheres near pushing the horns high end hard

so theres something majorly screwed up with either your impediance match or you PA mixing to have allot of hiss like that.

I did live live sound work for decades and if I was having bad guitar sound using mics or DI boxes coming off the speaker jacks,

99% of the time it was because of the jackass playing guitar didnt know how to get a decent sound on stage.

The PA simply makes whatever bad or good sound the guitarist has louder. Even then most PA's have an EQ where you can roll

off most of the bad frequencies and get things to blend. If that isnt enough to get a good sound, then the stage sound

must truley suck bad as well.

RCM is on point. A de-esser acts only when sibilance in a singer's voice (or other source) creates a dynamic spike at a given, typically narrow range.

There are several ways of achieving this. The classic is broadband compression triggered by a sidechain keyed to a narrow frequency range tuned to the 'sibilant' range of the source.

This Wikipedia article gives a solid, concise description of the main varieties of de-essing: http://en.wikipedia.org/wiki/De-essing

Yup. I'd be extremely surprised if it worked.

I think you need a gate.

For something as dynamic as a guitar, you'd need to have a damn good gate and a whole lotta luck.

Is the amp abnormally hissy when compared to other amps of that kind? Does it need servicing of some kind? Or a modification?

It really depends on the material. If hes playing loud passages, which it sounds like he is, you just need to adjust the settings.

It's possible. I've done it before. It's just not ideal or easy, in my opinion. You can do it with a decent noise gate and if you're not playing with that many dynamics. I mean, there's a reason why most guitarists don't play with noise gates.

I use a noise surpressor in my large pedal board. Its just a simple gate with an attack and release sensitivity knobs. You set above the noise floor and set how quickly it clamps down

after playing the last note. It has no affect on dynamics when playing because the gate only functions when the strings stop moving for a period of time depending on how you set it.

You can set it to clamp down too quickly of course and it can sound choppy. not having enough signal gain turning down the volume affects it too.

The subtle clamping that might be heard is still a hundred times better than having all the noise and hiss of high gain boxes running full bore into an amp and the associated feedback that can occur. Unless you're recording, its not someting that would be blatently obvious to a live audiance. Even recording with it which I often do, it has no noticable effects on any dynamics.

If you're talking about using a gate on recorded tracks where the signal comes from a miced speaker, then I'd say sure, gates sound pretty suckey on recorded tracks, but a live righ with alot of gain boxes, its the only way to go.

I know the JMP-1 theoretically has speaker emulated outputs, but it's a 17 year old piece of technology. I really don't think I'd enjoy playing one plugged into a PA system.