how reducing noise in guitar preamps?

What is the s/n of the pickup? Of the preamp? Of the amp? The end to end system? If the system isnt any better than about 60dB, you will need a gate if recording. If you are playing in a smoky honky tonk where you cant hear yourself play over the rest of the noise, who cares.

No Ley Line detector?

But I did some geetar mods some 20 years ago, by putting in active electronics in the guitar, very quite indeed. but pre surface mount . Big XLR on the side, iso feeds of each pickup.

The muso couldnt cope, too clean!

martin

a guitar distorsion box is commonly something that amplifies many times the input signal,then changes it shape by a non linear stage,that could be an op amp with antiparallel of diodes on feedback network, even using an OP27,of course not the state of art in low noise,i 'm not able to obtain the low noise of some pedals using less noble op amps as ne5532

even bigger is the difference with digitally controlled rack effects as roctktron using HUSH super C noise reduction,i guess this is an example of dynamic noise reduction,i.e. apparent but effective ,maybe an evolution of noise gates

i'm not interested in noise gates that switch off completely the signal under a certain threshold

anyone can help me in finding infos about how to obtain good results in s/n?thank you

Diego,Italy

The s/n of the pickup signal itself will depend hugely on the environment due to the likely induction from stray magnetic fields and the like.

Acheiving ~ 100dB s/n from the elctronics is quite trivially simple though.

Graham

"blisca"

Use them as either a source follower or with the drain as the output with gain set to around 3 to 5 times.

The input load should be 1 Mohm or greater with a series resistor of 4.7 kohms - resistor type does NOT matter here.

However, most guitar PUs produce significant buzzing and humming noise which makes low noise pre-amps a waste of effort.

....... Phil

thank you all for interesting answers, about the noise of the pick up i would consider everything comes from pick up as signal for now,the hum depends a lot by the environment (just if u change the angle of the guitar relatively to the noise source the hum changes a lot)and changes if pick ups are humbucking,active and so on I would like focusize about how to reduce the "hiss",and that does'not depends from the pickup ,i guess it depends more by topology,active components and resistence thermal noise,(correct?)

an

ne5532

which

Well, the 2n5459 has around 3nv/rthz at 1k, more at lower frequency, so it is a poor choice compared to a 2sk162, which is around 0.6nV/sqrthz (26 ohms noise resistance).

I wouldn't use more than a 1k series resister.

A typical pickup might be around 5k resistance, so where extraneous noise happens to be low, a 5k extra resistance is around sqrt(2) more noise than ideal. No point in adding noise when not necessary.

Not really. Do you actually have an amp and guitar? I do, in fact several, and I just pluged one in to test, and I am afraid that your information is a tad erroneous.

For the purposes of this test it was my Marshal AVT150 (the world leader in guitar amp sales), and my John Connelly Maple Neck Les Paul, lovely smooth neck indeed. The amp set clean, has very low noise indeed, you have to be right up to the speaker to hear the noise. On inserting the jack into and out of the guitar it is abundantly clear that the amp is the dominant noise source. There is very little change in noise level, well so long as the guitar is away from the amp by a couple of feet so as to not pick up the transformer field.

I could of course try the same experiment with my Gibson Explorer, and my Fender Twin, but the results will be the same.

Kevin Aylward B.Sc. snipped-for-privacy@anasoft.co.uk

"There are none more ignorant and useless,than they that seek answers on their knees, with their eyes closed"

Why use a resistor in series with the input of the jfet, which is already high impedance? What am I missing here?

In message , dated Fri, 15 Sep 2006, snipped-for-privacy@sushi.com writes

I wondered as well; I thought it might be to make a crude r.f. filter.

"Kevin Aylward"

Electric guitar pickups are high impedance devices.

Electric guitar pickups are high impedance, around 50 kohms to 100 kohms at high frequencies .

...... Phil

The outside world is a cruel place.

........ Phil

LOL !

Anyone would think Kevin was designing a low-Z mic amp.

Graham

Is this protection when the circuit is not powered but still hooked up?

Oh...

Kevin Aylward B.Sc. snipped-for-privacy@anasoft.co.uk

"There are none more ignorant and useless,than they that seek answers on their knees, with their eyes closed"

And your point would be?

And your point would be?

A typical model of a guitar pickup is around 5k in series with 1H. At

Secondly, this impedance dose not generate thermal noise, as would a 50k resister. The impedance of the guitar pickup is irrelevant as far as its thermal noise is concerned. So, what is your actual point about the high impedance, other than higher impedance are more susceptible to external interference?

I shall point out though, because there is an erroneous implication in your comments, fets are not used because the have high input impedance. It is of course, trivial to design a high impedance amplifier with a bipoler devices. The reason is that fets have very low shot (current)noise. This means that the current noise dropped across the large inductive impedance is much reduced compared to bipolars.

No, not really.

Your kidding right?

Been playing sone I was 11 years old mate. Been through one or two guitars in the time, although I currently only have 4.

Yeah, sure...

Kevin Aylward B.Sc. snipped-for-privacy@anasoft.co.uk

"There are none more ignorant and useless,than they that seek answers on their knees, with their eyes closed"

Yes, and gate protection. Its not nice to send inputs naked into the world.

Kevin Aylward B.Sc. snipped-for-privacy@anasoft.co.uk

"There are none more ignorant and useless,than they that seek answers on their knees, with their eyes closed"

And after the guitar's 'volume' control ? What then ?

Graham

Very wise advice.

Graham

"Kevin Aylward"

The noise is mostly above that frequency.

The high source impedance of the guitar PU does NOT attenuate their thermal noise like a 5 k ohms resistor !!

DAMN SHAME what happens when the guitar's volume pot is turned down slightly from its max position - instantly making the source impedance very high and resistive ( 100 -200 kohms typical).

Kinda swamps the tiny noise contribution of a 4.7 k series resistor !!

Aylward is totally INSANE .

He plainly cannot even see the crucial word "most" in my para above.

He has also ignored the obvious fact that the word " which " connects my final comment TO the previous fact.

Standard ASININE performance for someone who has bi-polar disorder and ASD.

Seen, played and repaired most types of electric guitar too - Les Pauls, SGs, Strats, Teles etc.

Most electric guitar PUs in common use DO generate lots of buzz and hum.

Only a small fraction are relatively immune.

........ Phil