Re: The Last Word


"Brian Running" <brunning@xxxxxxxxxxxxxxxxx> wrote in message
news:vZ49l.16224$Ws1.9047@xxxxxxxxxxxxxxxxxxxxxxx
Mike Rieves wrote:

Brian, face it, in any real world live performance, if you're playing in
front of people, and especially if it's a party or club crowd, the
absolute, best, SNR you can hope for is around 50 to 60 dB,

I never said otherwise, and it may be true that 50 dB is the best you'll
get. What I said was that you can maximize your signal-to-noise ratio by
making sure that the signal source -- your bass -- is putting out the
strongest possible signal, so that the difference between the noise floor
of the circuitry and the music signal from the pickups is as large as
possible. This is irrefutable, it can't be argued. You are confusing
dynamic range with signal-to-noise ratio.

No, apparently you don't realize that at a given gig, the ratio of ambient
noise to peak music SPL is not only the dynamic range, it is the SNR for
that room at that time as well. You are copnfusing the SNR of the equipment
with the SNR of the system, which includes ambient noise in the room as
well.



and that's if you're prepared to play very loudly. In a typical medium
sized night club, the noise floor is going to be at least 70 dB SPL,
average, and that's early in the evening before everyone gets drunk. The
max peak music SPL the crowd is likely to put up with is going to be 110
to 120 dB, with average SPL around 90 to 100 dB. That gives a best case
scenario of 50 dB peak and 30 dB average. That means that as long as your
instrument's SNR is 60 dB or better, no one in the crowd is going to hear
any noise.

No, it doesn't. As I said before, you're confusing dynamic range with
signal-to-noise ratio. SPL and S/N are not comparable, one's a ratio and
the other's an absolute level of sound pressure. You're saying that a
bass with a S/N of 60 dB means that the level of its noise will be 60 dB
SPL, and that's obviously wrong. Think about that for a second, your bass
alone producing noise -- just noise -- at a 60 dB SPL. Does that register
with you?

If so, it isn't because the bassist has the volume on his bass turned down
too low. He needs to get his bass fixed, because it it's producing thsat
much noise, he has a problem with it, or he's using non-humbuckers and there
is a lot of electrical noise in the room.

Any electronic circuitry, especially circuitry containing resistors and
potentiometers, is going to create a certain amount of noise. We hear it
as hiss. That hiss is independent of the level of the desired signal.
Everyone has heard this, you can turn the volume all the way down on and
still hear hiss coming from the speakers.

When the volume is truned all the way down on the bass, the hiss is *not*
coming from the pickup, because the hot side and the ground side are
electrically the same point. Any hiss will be coming from farther up the
line.

Every single component of the signal chain will add a little bit more.
That noise floor can't be avoided. It gets amplified right along with the
desired musical signal, every gain stage will increase its level a little
bit. The only way to minimize it is to ensure that the desired musical
signal is at as high a level as possible (and by "as possible," I mean
without distortion and maintaining sufficient headroom) so that the
difference between the level of the noise floor and the level of the
desired signal is as great as possible. It starts at the beginning of the
signal chain, the signal-to-noise ratio will never get better than the
original source, it can only get worse. If you run your bass at a low
level, then you are minimizing the difference between the desired signal
and the noise floor. Then it goes to the pre-amp, and it all gets
amplified, noise floor and desired signal, and that happens at each gain
stage. Your bass, by itself, may have a maximum signal-to-noise ratio of
70 dB, for instance, but after the pre-amp, that noise floor is going to be
amplified. You keep comparing signal-to-noise ratios to sound pressure
levels, and those are two completely different things, it's
apples-to-oranges. A 70 dB S/N does not compare in any way to a 120 dB
SPL.

If you have rig with a 70 dB S/N and it is capable of max peak levels of 120
dB wide open, your ambient noise level with the rig wide open will be 50 dB
SPL when you aren't playing. If you have it turned down so that it's only
producing max SPL of 100 dB, and you stop playing your ambient noise is
going to be 30 dB SPL. Where the instrument volume control is set is *NOT*
going to change the S/N of output of the bass, any noise in the pickup is
going to be attenuated exactly the same as any signal by the volume control.
Turning the bass volume control is going to increase the signal and any
noise by exactly the same amount, so if you have a noisy pickup, turning the
volume control wide open isn't going to help things a bit. Under normal
circumstances turning the volume control wide open will give you the max
signal to start with, so you have to use less gain, and therefore, any noise
inherent in the system after the insturment will be minimized.
As I said in my first post in this thread, I always run my volume
controls wide open, I even removed the volume control on my Gremlin and
replaced it with a 500 K blend control. I do that for two reasons, because I
record and I want to keep ambient noise to a minimum and because ai like the
tone of the instrument better with the volime wide open. I never disagreed
with your conclusions, just the reasoning you used to get to them. You don't
know very much about electronics and you bandy terms around that you really
don't fully understand. Example dynamic range vs SNR. If an amp has an SNR
of 100 dB, that means that with the volume control wide open, the noise
floor will be 100 dB below the peak output of the amp. The usable dynamic
range of that amp will then be 100 dB, which is the difference between the
highest output level it can produce and its noise floor


And of course, we all know that when the band's pumping out 120 dB from
the PA, no one hears the noise. That's not the point. In between songs,
there's very often a lot of audible noise in the PA, and some of it is the
noise floor of the various pieces of gear in the signal chain, amplified
to the point where it's very audible, right along with the fluorescent
lights and dimmers and refrigeration compressors and all that other crap.
Anyone who's actually played out in a live setting knows this, regardless
of Aaron Borgman's strange arguments to the contrary.

What you and Aaron are arguing is this: Why not try to minimize the
amount of noise as much as possible? There's no reason not to. There's
no cost involved in turning up your bass's volume control, there's no cost
involved in proper gain staging, these are just ordinary, normal steps
that any sound professional will take. How on earth can you question
this?

Once again I'll ask, when have you ever heard noise from the band over the
ambient crowd noise because the bassist or guitarist had his instrument
volume control set too low? It just doesn't happen in the real world. I've
never seen it, and I seriously doubt anyone here has either. I know several
professional bassists who regularly run their instrument volume controls on
8 or 9, and change the volume settings from song to song, and even during
songs. Two that I've seen personally do that are Mike Chapman and Dave Roe.
Both played in house bands at the Windjammer Lounge here, and I saw them
play lots of times. If you don't know who they are, just google them. I'm
sure that when they're in the studio, they run their bass volumes wide open,
but live gigs are a whole 'nuther story. To be fair, I don't know of any
bass player who runs the volume below halfway, and most I know run the
volume at least on 8 or better. If I remember correctly, Aaron has a EE
degree, so you should know better than to argue with him in the forst place
about things like this. This is one of those cases where a little knowledge
is no better than no knowledge. Sure you want to maximize signal to noise,
but when you reach a practical max, nothing else you do is going to provide
any audible difference whatsoever. On most bass guitars with decent bass
rigs, you'll reach that practical max for a typical gig with the bass volume
set somewhere around halfway up. Since nearly every bass player plays with
it higher than that, it's a total non-issue.


.

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