Treble hiss- pre amp or pickup?

[DangerDan]

When i turn up the treble on my cort curbow 4 string i get an awful hiss on my output, it goes away if i roll my treble off completely.

Im trying to work out if it is a problem with my pickup or if it is a problem with my pre amp.

Thanks in advance for any light you can shed on this!

[morgano]

Most likely to be the preamp. Active circuitry will always introduce some amount of noise, the amount depends on the type/quality of the circuitry.

You could maybe consider converting the bass to passive, or adding an active/passive switch.

Also, if you don't need the top-end, turn off the tweeter on your cabinet (if there is a tweeter and switch for it of course).

[DangerDan]

Thank you very much Morgano, much appreciated! I will probably swap the pre amp out, was wary of doing that if it was likely to be the pickup introducing the noise in the first place.

Do pre amps fry over time? I had never noticed the sound until recentely.

[morgano]

I wouldn't have thought anything would have happened to the preamp. Are you listening to the bass on a different amp to before? An amp/cabinet with a tweeter/horn will show up the hiss more.

Also be worth checking the battery, but a low battery tends to produce distortion rather than hiss.

[DangerDan]

I got a new cab, but it doesn't have a tweeter. (I changed the battery out recentely too, but im sure it will be worth me swapping it out again, just to eliminate it as an issue!)

It might just be that i've noticed it as i usually only play this bass at practice or on stage, never in the quiet of my home/ through headphones, so never really noted it before. Obviously now i have noticed it, i can't unhear it. Also, i never really used effects before, but now im playing about with them more, some are practically unusable due to the amount of noise they kick up.

Edited December 16, 2016 by DangerDan

[Chienmortbb]

Sounds like a poorly designed pre amp to me.

[Grangur]

《Stupid noob suggestion》 Have you tried a different lead? I was playing last night and found i had a hiss going on. Changed the lead and problem solved. 《/Stupid noob suggestion》

[brensabre79]

It's probably always been there, but you'll definitely notice it more on headphones.
Active preamps almost always introduce some level of noise, the more expensive ones less than the cheaper ones as a rule...
Effects pedals tend to introduce [i]and[/i] amplify noise - which is why many people have a noise suppressor on their board.

Like Grangur has pointed out, the lead can also affect things, some leads lose a lot of treble from the signal - which is normally seen as a bad thing - in some cases this will remove the hiss generated by noisy preamps/pedals. Which is fine if you don't want lots of treble, but I'll wager that if you're getting lots of hiss because you have the treble turned all the way up, you're looking for more treble...

It's worth remembering that on most active treble/bass controls, halfway is normal, all the way up is maximum boost.