Carvin SB4001 shielding hiss on active mode??

Rafescow · #1 03-12-2013, 01:04 PM

My 2 months-old Carvin SB4001 is making noises in active mode as the treble is turned up, which are even higher when the pickup's are soloed, and EVEN HIGHER when I'm not touching the strings or any metalic part of the bass (tuners, bridge, knobs/knob plate, etc).
I know this is a common thing among between active basses, but Carvin's J99A pickups are famous for being the most silent pickups out there, which is getting me worried.
Also, the tone knob makes a very loud noise when turned if I'm not touching these metalic parts of the bass (it doesn't do that on passive mode though).
I was thinking it would be a matter of poor shielding, but then I unscrewed the knob plate and the inside was entirely covered with copper foil.
Does anyone else has similar experience with a Carvin bass? Is this noise expected or not?

I recorded it through my audio interface with some annotations at SoundCloud so you guys can hear it: https://soundcloud.com/rafael-freita...001-noise-test

Any input would be appreciated. Thanks!

Obs: My bass has the Master Vol/Blend setup, if that helps at all
Obs 2: Already tried changing batteries. Put brand new ones and no changes at all

rmars · #2 03-12-2013, 02:13 PM

Link to clip doesn't work.

I don't have a SB (yet, mine is on order) but I do have quite a bit of experience with single coil loaded J basses.

The pickups are single coils and should be fairly quiet when balanced but will hum when solo'd. Depending on the environment this could be anything from tolerable to serious hum. If you turn up the treble is would increase the amount of hum as it's going to be most prominent in those frequencies. You can shield till the cows come home but single coil can and will have some degree of hum when solo'd. Rolling off the tone can tame the hum a bit if you choose to solo a pickup... which leads to the part of your issue that doesn't make sense.

Why your bass is making noise when you when you touch the tone knob I'm not sure. That sounds like a possible ground issue or a bad pot. What ever it is could be extrapolating the typical single coil hum especially if your boosting the treble. I've heard the internal gain comes set too high on the preamps sometimes and again that would only make matters worse.

Jarrett · #3 03-12-2013, 02:16 PM

Not normal. Send it back to Carvin to get it fixed. Talk to Albert there.

rmars · #4 03-12-2013, 02:21 PM

Quote:

Originally Posted by Jarrett

Not normal. Send it back to Carvin to get it fixed. Talk to Albert there.

Jarrett, while were at it: how quiet are the pickups when solo'd? If I recall you are using the standard J99A's.

I've heard they are fairly quiet but I would assume they would still have some degree of hum being that they are single coils. Please correct me if I'm wrong.

Jarrett · #5 03-12-2013, 02:31 PM

Yes, all J99A's on mine. Mine have a slight hum when solo'ed in some environments. It's so little that I don't typically notice it. I used to have an MP3 where I put the SB up to a computer monitor and went from pickup to pickup and it was just slight hum, but I can't find it now. I can't hear the hum live for sure.

Rafescow · #6 03-12-2013, 02:34 PM

Quote:

Originally Posted by rmars

Link to clip doesn't work.

I don't have a SB (yet, mine is on order) but I do have quite a bit of experience with single coil loaded J basses.

The pickups are single coils and should be fairly quiet when balanced but will hum when solo'd. Depending on the environment this could be anything from tolerable to serious hum. If you turn up the treble is would increase the amount of hum as it's going to be most prominent in those frequencies. You can shield till the cows come home but single coil can and will have some degree of hum when solo'd. Rolling off the tone can tame the hum a bit if you choose to solo a pickup... which leads to the part of your issue that doesn't make sense.

Why your bass is making noise when you when you touch the tone knob I'm not sure. That sounds like a possible ground issue or a bad pot. What ever it is could be extrapolating the typical single coil hum especially if your boosting the treble. I've heard the internal gain comes set too high on the preamps sometimes and again that would only make matters worse.

Yeah, I know that is common among active basses in general. Problem is, Carvin basses aren't "general"... they're top notch instruments and I really wasn't expecting to have this kind of problem with them...

Quote:

Originally Posted by Jarrett

Not normal. Send it back to Carvin to get it fixed. Talk to Albert there.

That's what I was afraid of... damn. Gonna give me a little bit of work since I live in Brazil and the only Carvin dealers here are in another city

Jarrett · #7 03-12-2013, 02:36 PM

The only problems I've had with my Carvins has been minor electronics stuff like this. Their QA process isn't the greatest, but their support is. I'm sure they would work with you to get a resolution.

Rafescow · #8 03-12-2013, 08:47 PM

Quote:

Originally Posted by Jarrett

The only problems I've had with my Carvins has been minor electronics stuff like this. Their QA process isn't the greatest, but their support is. I'm sure they would work with you to get a resolution.

Yeah, they said they could send me replacement electronics for free (though I can't replace them by myself, I'd need a luthier for that) or have my bass sent to an authorized dealer, but then it's not in my city.

And I bought with this bass a Sansamp BDDI that simply stopped working one week after... man, that's what I would call bad luck

Obs: the soundclip was set to private, I made it public. See if it works now!

ddnidd1 · #9 03-12-2013, 09:02 PM

I listened to your clip on studio monitors and Beyer Dynamic DT-990 Pro headphones and can't hear any electronically generated hiss at all.

At one point I do hear a little single coil noise from an external source.

The noise you hear when you turn the tone pot is just a slightly scratchy, as in possibly dirty, pot.

You can swap out the electronics, but you won't change the 'noises' you're hearing.

Rafescow · #10 03-12-2013, 09:13 PM

Quote:

Originally Posted by ddnidd1

I listened to your clip on studio monitors and can't hear any electronically generated hiss.

At one point I do hear a little single coil noise from an external source.

The noise you hear when you turn the tone pot is just a slightly scratchy, as in possibly dirty, pot.

You can swap out the electronics, but you won't change the 'noises' you're hearing.

I really don't think it is a dirty pot: as said, that scratchy noise doesn't happen when i'm touching any other metalic part of the bass (i.e. one hand holding the strings and another hand adjusting knob = no scratch, but only one hand adjusting tone knob = scratch). Would that happen if it was dirt?