Topic: JB3 hd noise = audible on recording? + preventing shutdown!

[dklein]

The noise corresponds to hard drive writes.  To the best of my memory, it occurs every 9 seconds, alternating between single and double high pitched 'beeps' that become audible during quiet portions if some post gain is applied (or if your source was very quiet). 

The JB3 buffers data and then writes, quite frequently when your recording wave and much less on mp3.  The write seems to cause noise in the analog...my guess is thru the power supply.  Running an ammeter on the JB3 shows each write is a big power sucker (which is also how I correlated the noise to the write event).

This all goes away with optical connections.

[Humbug]

I dunno if this helps, but 95% of the stuff I record is loud rock music.

However the remaining 5% is acoustic, minimally ampified.

I've never heard any artefacts whatsoever in my recordings, either on the acoustic stuff or between tracks at the rock gigs.

Cheers

Humbug

[dklein]

well if you want to hear it, just record line-in without anything attached to the JB3.
Turn up the volume on playback (of course it's louder if you set the JB3 to +12dB when recording)

Once you've heard it you'll know when you hear it again...

[spyder9]

Dudes,

The HD drive problem is simple:  Get a Preamp!  I had the same problem with the HD noise ( mini mics > battery box > JB3).  Once I got a Denecke AD-20, problem solved.  The preamp will bring the recording up to line level.   

[Brian Skalinder]

The HD drive problem is simple:  Get a Preamp!  I had the same problem with the HD noise ( mini mics > battery box > JB3).  Once I got a Denecke AD-20, problem solved.  The preamp will bring the recording up to line level.   

Well, in your case you got a preamp *and* ADC.  A preamp alone *should* get levels up to the point (line-level) where the noise is inaudible, but my understanding from David Klein's testing is that the noise is still there - just inaudible.

[spyder9]

Well, in your case you got a preamp *and* ADC.  A preamp alone *should* get levels up to the point (line-level) where the noise is inaudible, but my understanding from David Klein's testing is that the noise is still there - just inaudible.

Inaudible.  Enough said.   

[Brian Skalinder]

Inaudible.  Enough said.   

Not enough said. 

I haven't done the testing, so I don't know for certain if it'd be inaudible on my system with my ears.  I'm nitpicky that way - won't believe it as 100% fact unless I've done it myself.  But on this one, I'm not gonna put the time in to test so I trust David's tests. 

That said, inaudible to some is not inaudible to others.  I've hosted enough blind comparisons here to know that different people hear different things from the same sources.  Not saying David's not correct - for his recording / playback / ears - just that every situation is different.

And even if it's inaudible now, it may become audible after processing.  For example, compressing my recording to reduce dynamic range and then raising levels to get my peaks back up.  Doing so would, of course, raise the relative noise level.

[spyder9]

I actually listen to all my shows through canalphones while taping.  Haven't heard a peep.  Even during the quietest moments between songs.  And I squint to listen for anamolies.  I think anymore time put in beyond adding a preamp would be neurotic.  That's just my opinion.

[dklein]

I'll add that 'inaudible' really depends on what you're listening to.  You might not hear it during the music, but you could between songs if the crowd is quiet.  The hard drive noise peaks at -70 dB or so when the JB3 is set to line-in, 0 dB.

As far as using mics go, the attached sample is the noise you get at the +12 dB setting with 20 dB of gain in post (that's a total of 32 dB).  That's probably typical for a real low sensitivity mic.  Whether or not your music drowns it out depends on what you're recording.

If you can drive proper line level signals with a preamp and leave the JB3 at 0 dB, then this sound is down 70 dB which I think we can probably call inaudible, but as Brian says - prove it for yourself.

[dklein]

Here's part of another sample I just posted to the NJB3 tapers group.  This is using CSB>JB3, line-in +12 dB with post gain of 23 dB.
2 parts - the silence b/w songs and then the beginning of a song where it is audible over the music.

[spyder9]

I'll add that 'inaudible' really depends on what you're listening to.  You might not hear it during the music, but you could between songs if the crowd is quiet.  The hard drive noise peaks at -70 dB or so when the JB3 is set to line-in, 0 dB.

As far as using mics go, the attached sample is the noise you get at the +12 dB setting with 20 dB of gain in post (that's a total of 32 dB).  That's probably typical for a real low sensitivity mic.  Whether or not your music drowns it out depends on what you're recording.

If you can drive proper line level signals with a preamp and leave the JB3 at 0 dB, then this sound is down 70 dB which I think we can probably call inaudible, but as Brian says - prove it for yourself.

Thank you for all your efforts.  You gave me advice back in June regarding this "noise."  I went w/ the AD20 and have not heard the "noise" again.  Could you post the same sample but with the AD20 wedged in there.  I think that will be a fair comparison.  If you can't, I will after the holiday.

[Brian Skalinder]

I went w/ the AD20 and have not heard the "noise" again.  Could you post the same sample but with the AD20 wedged in there.

No test needed if you're concerned about JB3 gain stage and ADC noise, since the AD20 provides gain and A>D outside of the JB3.  The noise is only an issue when the gain and ADC are performed inside the JB3.  The only noise you should hear with the AD20 in the chain is the noise from your mics - self-noise, noise in the surrounding environment, etc.  But none from the JB3.  Make sense?

[spyder9]

Precisely. I think I said that above, but not in those words. 

Battery box people, just get a preamp.  UA5, Denecke AD20, etc.  It will eliminate the HD noise from your recordings.

Happy Thanksgiving Brian.

[Brian Skalinder]

Precisely. I think I said that above, but not in those words.

No no no.  Forgive me for continuing to harp, but it's important to get this right.  I believe we're saying the same thing.  However...

Battery box people, just get a preamp.  UA5, Denecke AD20, etc.  It will eliminate the HD noise from your recordings.

The UA5 and AD-20 both contain a gain stage (preamp) and an ADC.  A preamp alone will not remove the sound.  It may minimize the noise by making it quieter relative to the stronger musical signal, so much so that the recordings are good enough for an individual's taste, but it won't *remove* the noise.  Only an external ADC will remove the noise outright.

So, there are really two statements we can make here, expanding on your quote above:

[1]  Battery box people, just get an outboard preamp to minimize* the HD noise for most recordings.
[2]  Battery box people, just get an outboard preamp *and* ADC to remove the noise completely.

*  Render inaudible?  Depends, I suppose, I haven't done the testing myself

My whole point, and maybe I'm just getting caught up in semantics (wouldn't be the first time!):  to suggest that an outboard preamp alone removes the noise is incorrect.  To remove it entirely requires an outboard ADC.

And backatcha:  Happy Thanksgiving!!

[spyder9]

T+, Brian is correct!