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preamp output is too hot (?!?!?)
- Thread starter Bob_Ross
- Start date
As long as the actual sound from the bass output is good, undistorted and with good noise performance, turning down the output volume is not a problem to be fixed, IMO.
Otto
Otto
Just use that weird knob on there called "volume".
I had the same issue with an Audere on some amplifiers. I did some research and I found out that there was this knob on the preamp that controlled the level of its output, so I turned it down around ten percent, and I never had that problem again.
I had the same issue with an Audere on some amplifiers. I did some research and I found out that there was this knob on the preamp that controlled the level of its output, so I turned it down around ten percent, and I never had that problem again.
Well, if that's how much it takes, that's how much it takes. Better to have too much than too little; you can always dial it back.
- Apr 18, 2008
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- Disclosures
- I'm highly opinionated and extremely self-assured
If you skip the stompboxes, does the bass clip the preamp stage of your amplifier? Would it help to use the effects loop of your amp (assuming it has one; I don't see your rig listed anywhere in your profile)?
Update: Did some more screwing around/troubleshooting in the rehearsal studio last night. There's definitely something funky about the direct interaction between this bass and my pedalboard.
- any of my other basses, either active or passive, work fine w/ the pedalboard. No clipping, no inordinately loud output from the instrument.
- bypassing the pedalboard (bass plugged directly into the amp) this new Bart-equipped problem child is definitely louder than any of my other basses. Backing the NTMB volume controls down 30-40% cleans up the sound just fine.
- when I plug that bass into my pedalboard, even with the NTMB volume controls down 40-50% it still clips the inputs to the stompboxes. Fuzzy distortion + no super-lows nor super-highs. I have to roll the NTMB volume controls down to almost nothing (85-90%) before the clipping stops...and at that point there still seems to be a loss of super-lows & super-highs.
- Here's where it gets really odd: I plugged the bass into an Ernie Ball passive volume pedal (the old stereo model) before hitting the pedal board. Kept the onboard NTMB volume controls at full CW, but backed off the Ernie Ball volume pedal maybe 30-40%. SUCCESS! No clipping of the stompboxes.
So...why would plugging the instrument directly into the pedalboard clip even when the bass' volume controls are dialed way back, but not clip the pedalboard when the bass' volume controls are dialed all the way up and then attenuated via the downstream volume pedal? I'm wondering if there's some freak impedance mismatch...
It does clip the preamp stage of my amp, though not excessively. If I back off the onboard NTMB volume controls ~30-40% the bass sounds fine plugged direct into the amp. Since everything on my pedalboard is an instrument-level stompbox I haven't tried using the line-level effects loop from my rig (Alembic F1-X preamp feeding a Crown power amp)...but maybe I'll give that a shot.
Yes, it's impedance. Passive bass outputs a high impedance signal, but after it's run through a preamp of any flavor, it becomes low impedance. The volume pedal adds some impedance back to the signal change. A buffered effect pedal will also make a high-impedance signal into a low impedance one. Fuzz pedals in particular sound different if they're driven with a low-impedance signal.
Have you contacted Bartolini?
If your bass volume control is linear, with it rolled back this far, it is probably around about 12-15dB of attenuation. More likely the vol pot is a log taper which equates to I guess around 30dB!
No amount of pickup height adjustment or series to parallel rewiring will get you even close to that kind of attenuation. This really sounds like it could be faulty.
Typically a volume pedal designed for passive guitars is simply a large value (250K-500K) pot. And if you feed this with a low impedence source, it will sweep more abruptly. (In fact, with a really lo z signal a 250-500k pot will act almost like an on-off switch!) I'd think that's why it is giving you the same attenuation at 60-70% as your bass vol pot does at 15%. If your volume pedal is made for low Z sources, (you said it was stereo, so I'm guessing it could be for keyboards or something) then it probably has a 25-50k pot in it. In which case it will sweep perfectly fine for your (active) bass. So if that's the case, I'm guessing the difference in attenuation you are experiencing might be because the volume pot in your bass is linear.
Anyway, as I said this means you need 12-15dB quieter signal even with the trimpot all the way down, and that doesn't sound right to me.
Yeah, it's gotta be a problem with the preamp. The gain trimpot should be able to tame that clipping issue. May need a replacement module.
How is the trim pot set?
If you like to boost the bass, you may have to lower the gain a little more.
See posts #1 and 9; it's all the way down. Really scary that this bass can get even louder!
Sorry, missed reading thru the first section again.
'Rigging' it with more attenuation could allow the preamp to present other problems if it is faulty (and there's no reason for it to be this hot).
I'd return/replace it. Or maybe it would be good coupled to some really low output pickups (if the signal is clean, and the EQ works)- no booster needed.
'Rigging' it with more attenuation could allow the preamp to present other problems if it is faulty (and there's no reason for it to be this hot).
I'd return/replace it. Or maybe it would be good coupled to some really low output pickups (if the signal is clean, and the EQ works)- no booster needed.
Update: The vendor sent me a replacement NTMB preamp, I installed it, and everything works as it should: Output isn't too hot when the internal trim pot is at a nominal level and the Volume pots are full clockwise, nothing's clipping, all is good in the world. So the original NTMB was clearly defective.
:::happy dance:::
:::happy dance:::
I had the same problem with a newly installed NTMB HR 2.4AP/916.
Signal was distorted when the bass volume was at full.
I lowered the pickup height.
Signal was distorted when the bass volume was at full.
I lowered the pickup height.
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