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Noob looking for simple bass guitar preamp

Started by yapper, December 10, 2017, 04:53:31 AM

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yapper

I'm looking for a straightforward 'flat' preamp for my passive p-bass clone. Ideally something with 10dB gain. Is there a cheap-ish kit out that that would do this? I've seen various things on ebay but they all seem to be embellished with tone adjustments.

Thanks in advance for any pointers,

Mark

jimilee

What context are you using it? As a bassist myself for most of my 46 years, an external preamp is not anything I've ever actively looked for.


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yapper

Primarily to improve noise. Somewhere I'm picking up noise and I found by using an old headphone amp between the bass and the cable to the (main) amp the signal to noise levels are much better. I'm not necessarily looking for an external amp - today I've come across some circuits based on a J201 FET that look promising and it's simple enough to fit inside the bass.

jimilee

Like just a basic boost or something then? That's really strange you're getting noise that filters out that easily. Is it like a 60 cycle hum?


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Pedal building is like the opposite of sex.  All the fun stuff happens before you get in the box.

soldersqueeze

 Is there a chance your bass isn't grounded properly? The headphone amp could be sorting a grounding issue between your bass and amplifier?
Just a thought, but as jimilee says it's a strange situation

yapper

I suspect it's either my cheap guitar cable, or the amp that's picking up the noise so simply (pre) amplifying the guitar signal means it's now xdB louder than the noise.

The bass appears to be grounded properly. I've got the cavities lined with good quality copper tape with overlapping seams and the bridge is grounded back to the pots.

Changing the focus from amps to cable, can you recommend a good cable (either a ready made cord or a brand/type of cable) that is well screened?

jimilee

I use Hotwire. Cheapish but never an issue.is where it's plugged in grounded? Is the headphone amp battery or plug in?


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Pedal building is like the opposite of sex.  All the fun stuff happens before you get in the box.

yapper

I've located the source of my noise. It was the 9V DC PSU for a pedal. Running the pedal off a batteries got rid of the noise!

jimilee

Quote from: yapper on December 10, 2017, 10:49:48 PM
I've located the source of my noise. It was the 9V DC PSU for a pedal. Running the pedal off a batteries got rid of the noise!
Excellent! Bad psu or house wiring is acting wonky? The latter happens from time to time.


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Pedal building is like the opposite of sex.  All the fun stuff happens before you get in the box.

yapper

It's a bad PSU I think. The output smoothing capacitor looks like it's leaking.

jimilee

Ahhh. Glad that's all it was.


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Pedal building is like the opposite of sex.  All the fun stuff happens before you get in the box.