Behringer PMX-2000 Rumble Filter

[Martin]

I'm using a PMX-2000 with Yamaha 15" cabinets to host Karaoke. The
music is brought from my laptop to the "tape in" stereo channel, and
I'm running Shure SM-58s into channels 1, 2, and 3.

The Behringer has a pushbutton "rumble filter", which I assume is meant
to cut low-frequency handling noise, that applies simutaneously to mic
channels 1 through 6. My problem is I can't detect any effect of
engaging the filter, other than the fact that a front-panel light comes
on when I push the button in. There is no detectable change in the
sound characteristics. If I tap steadily on the microphone body while
switching the filter in and out, I can hear no change.

Would someone else who owns the PMX-2000 please repeat my experiment,
and tell me if their rumble filter seems to be effective? I'd like to
know whether my specific unit is broken, or if perhaps it's just a bad
design with the cutoff not properly set.

If the latter is true, any techie guys out there with mod instructions?

thanks,

Martin

[TimPerry]

Post by Martin
I'm using a PMX-2000 with Yamaha 15" cabinets to host Karaoke. The
music is brought from my laptop to the "tape in" stereo channel, and
I'm running Shure SM-58s into channels 1, 2, and 3.
The Behringer has a pushbutton "rumble filter", which I assume is meant
to cut low-frequency handling noise, that applies simutaneously to mic
channels 1 through 6. My problem is I can't detect any effect of
engaging the filter, other than the fact that a front-panel light comes
on when I push the button in. There is no detectable change in the
sound characteristics. If I tap steadily on the microphone body while
switching the filter in and out, I can hear no change.
Would someone else who owns the PMX-2000 please repeat my experiment,
and tell me if their rumble filter seems to be effective? I'd like to
know whether my specific unit is broken, or if perhaps it's just a bad
design with the cutoff not properly set.
If the latter is true, any techie guys out there with mod instructions?
thanks,
Martin

my PMX-2000 measures -3dB @ 80 Hz -6 dB @ 45 Hz and -10 dB @ 30 hZ
with the runble filter in. EQ sw off and EQ pots at neutral.

[Martin]

Is the response flat with the filter out? Any idea if this is above or
below typical LF noise produced by handling? Does your filter
effectively cut this noise? I don't have any calibrated frequency
source to quantify my rolloff.

Martiner

[Martin]

Just had a thought - this weekend I could build a simple L-Pad to
attenuate my AC mains voltage to check the filter at 60 Hz. Comments?
What is the sensitivity of the MIC inputs 1-6?

Martin

Post by Martin
Is the response flat with the filter out? Any idea if this is above or
below typical LF noise produced by handling? Does your filter
effectively cut this noise? I don't have any calibrated frequency
source to quantify my rolloff.
Martiner

[Arny Krueger]

Post by Martin
Is the response flat with the filter out?

There's got to be another fixed roll-off in the 15-30 Hz
range.

Post by Martin
Any idea if this is above or below typical LF noise
produced by
handling?

From extensive experience multitrack recording, remixing and
analyzing live sound events I've got a lot of technical info
about handling noise:

(1) Handling noise has a sonic signature that is highly
dependent on the mic and the object that stimulates the
noise whether its the performer's hands or a mic clip or
whatever.

(2) Handling noise can be extremely broad band, high, mid
and low frequencies. It starts out as a series of impulses,
which are modified by the response of the mic cartridge and
the shock mounting of the mic cartridge, if there is any.

(3) It's generally easier and more effective to try to mute
the mic over the usually brief duration of each disturbance
(of which there are several in each incident) than it is to
try to filter it out over a longer period of time. That can
be done with recordings. But its only practical to use
longer mutes in live sound. (see below)

Post by Martin
Does your filter effectively cut this noise?

IME no such filter exists. However filtering can mitigate
the noise.

One of the best things I did to minimize handling noise was
to put felt padding on the inside of our praise team's mic
clips. Lot of people do this. Prior to that I migrated them
to mics that had more effective built-in shock mounting.

My best solution for handling noise is effective setup and
use of the scenes feature of my digital mixing console. A
fully muted mic (mains and monitors) produces no audible
handling noise. ;-)

Post by Martin
I don't have any calibrated frequency source to quantify
my rolloff.
Martiner

[Arny Krueger]

Post by Martin
I don't have any calibrated frequency source to quantify
my rolloff.

If you have a PC with some kind of halfways-decent audio
interface you can quantify the equipment quickly and easily
and without any out-of-pocket cost.

There is a downloadable freeware called the Audio Rightmark.

First you loop the input and output of your PC's audio
interface and evaluate it with the Audio Rightmark software.
This gives you noise, frequency response, and nonlinear
distortion tests. If your PC's audio interface is halfways
decent you move on to the next step.

Then, you break the loop and insert whatever equipment you
have, operating at unity gain. Repeat the Rightmark test and
note any differences.

[Martin]

So I "calibrate" by jumpering my soundcard's line in and line out, then
insert my system?

I wouldn't think "unity gain" of the system under test would have to be
set exactly, correct? As long as the line in to the soundcard is not
overdriven, of course? The measurement results would just then
indicate gain shift as well as frequency response.

I'll download Rightmark and the manuals.

Martin

Post by Arny Krueger

Post by Martin
I don't have any calibrated frequency source to quantify
my rolloff.

If you have a PC with some kind of halfways-decent audio
interface you can quantify the equipment quickly and easily
and without any out-of-pocket cost.
There is a downloadable freeware called the Audio Rightmark.
First you loop the input and output of your PC's audio
interface and evaluate it with the Audio Rightmark software.
This gives you noise, frequency response, and nonlinear
distortion tests. If your PC's audio interface is halfways
decent you move on to the next step.
Then, you break the loop and insert whatever equipment you
have, operating at unity gain. Repeat the Rightmark test and
note any differences.

[Arny Krueger]

Post by Martin
So I "calibrate" by jumpering my soundcard's line in and
line out, then insert my system?

That's the overview.

I recommending running the Rightmark procedure on the sound
card, make any gain adjustments required for the best
possible results, and then march on to testing any other
equipment.

Post by Martin
I wouldn't think "unity gain" of the system under test
would have to be set exactly, correct?

Level setting is part of the operation of the Rightmark
program. You don't have to be right on, but you do have to
be within a dB or so,

Post by Martin
As long as the line in to the soundcard is not
overdriven, of course?

That would be verified during the testing of the soundcard.

Post by Martin
The measurement results would just then indicate gain
shift as well as frequency response.

The software reports 1 KHz gain in real time during the
setup phase.

Post by Martin
I'll download Rightmark and the manuals.

It's all in the basic install package. Reading the manual
may be optional.

[Kevin T]

I must be missing something. You are using a $300 Behringer powered
head with MI cabs to play Kareoke yet you are looking for a knats ass
of detail on High Pass filters performance? I'm sure it works. But if
it's global & says as "rumble" not 80 or 100hz like most HP per channel
then its more like my Soundcraft Spirit 40hz subsonic global HP filter.
Its more likely for turtable feed back protection so you likely won't
hear any change with vocals . I'de use it just to keep the techno MP3s
from sucking up your power in subsonic waste.

"I hate Kareoke and her sister Annie too"

Kevin T

[Martin]

Yes, you missed the point. I'm trying to determine whether switching
in the filter does anything at all, ie "is it working?". Arny proposed
a test that would do this and also quantify the performance in detail,
which is fine with me and will also provide insight into why (if it's
working) it does or doesn't reduce handling noise of a microphone.

Martin

Post by Kevin T
I must be missing something. You are using a $300 Behringer powered
head with MI cabs to play Kareoke yet you are looking for a knats ass
of detail on High Pass filters performance? I'm sure it works. But if
it's global & says as "rumble" not 80 or 100hz like most HP per channel
then its more like my Soundcraft Spirit 40hz subsonic global HP filter.
Its more likely for turtable feed back protection so you likely won't
hear any change with vocals . I'de use it just to keep the techno MP3s
from sucking up your power in subsonic waste.
"I hate Kareoke and her sister Annie too"
Kevin T

[Peter Larsen]

Post by Martin
Yes, you missed the point. I'm trying to determine whether
switching in the filter does anything at all, ie "is it working?".
Arny proposed a test that would do this and also quantify the
performance in detail, which is fine with me and will also provide
insight into why (if it's working) it does or doesn't reduce
handling noise of a microphone.

It might be because handling noise is not rumble, but rather wideband.

Some mics have better vibration insulation of the capsule than others.

Handling noise also depends on whether the mic is handled, and if so,
how ... it is not something you can filter away if it is present in the
mic output signal.

Post by Martin
Martin

Kind regards

Peter Larsen

[Pooh Bear]

Post by Peter Larsen

Post by Martin
Yes, you missed the point. I'm trying to determine whether
switching in the filter does anything at all, ie "is it working?".
Arny proposed a test that would do this and also quantify the
performance in detail, which is fine with me and will also provide
insight into why (if it's working) it does or doesn't reduce
handling noise of a microphone.

It might be because handling noise is not rumble, but rather wideband.

I dunno. Most of it quite LF. Depends how it's being handled I guess ?

Post by Peter Larsen
Some mics have better vibration insulation of the capsule than others.
Handling noise also depends on whether the mic is handled, and if so,
how ... it is not something you can filter away if it is present in the
mic output signal.

I had a look on the Behringer site and downloaded the manual.

They give the example that the rumble filter is effective in reducing
handling noise. They don't however list a spec for the filter freq or
slope.

Certainly a classic 'rumble' filter would be hopeless at reducing handling
noise. You need a filter at 80-100 Hz or so.


Graham

[hank alrich]

Post by Martin
will also provide insight into why (if it's
working) it does or doesn't reduce handling noise of a microphone.

Because it's not the right filter to attempt that, even if it's working
properly. A rumble filter is a high-pass filter originally intended to
fight turntable rumble, which is well below the bulk of mic handling
noise. The best way to reduce mic handling noise is to use a mic that
was designed to be handled.

--
ha

[Martin]

Post by hank alrich

Post by Martin
will also provide insight into why (if it's
working) it does or doesn't reduce handling noise of a microphone.

Because it's not the right filter to attempt that, even if it's working
properly. A rumble filter is a high-pass filter originally intended to
fight turntable rumble, which is well below the bulk of mic handling
noise. The best way to reduce mic handling noise is to use a mic that
was designed to be handled.
--
ha

I'll have to disagree with that assumption - it's unlikely that this
"rumble filter" was designed with turntable applications in mind,
illustrated by the fact that it's implemented only in the (mono)
microphone channels. If a turntable were used with this mixer/amp, it
would be connected to a stereo channel without the option of routing
through this filter.

Unfortunately, the usage of an archaic term to describe the filter has
caused some confusion amongst folks not familiar with the particular
gear.

Martin

[hank alrich]

Post by Martin

Post by hank alrich

Post by Martin
will also provide insight into why (if it's
working) it does or doesn't reduce handling noise of a microphone.

Because it's not the right filter to attempt that, even if it's working
properly. A rumble filter is a high-pass filter originally intended to
fight turntable rumble, which is well below the bulk of mic handling
noise. The best way to reduce mic handling noise is to use a mic that
was designed to be handled.

I'll have to disagree with that assumption - it's unlikely that this
"rumble filter" was designed with turntable applications in mind,
illustrated by the fact that it's implemented only in the (mono)
microphone channels. If a turntable were used with this mixer/amp, it
would be connected to a stereo channel without the option of routing
through this filter.
Unfortunately, the usage of an archaic term to describe the filter has
caused some confusion amongst folks not familiar with the particular
gear.

Aaah, marketing... <g>

--
ha

[TimPerry]

Post by hank alrich

Post by Martin
Unfortunately, the usage of an archaic term to describe the filter has
caused some confusion amongst folks not familiar with the particular
gear.

Aaah, marketing... <g>
--
ha

amazing that its not called "the ultrafilter"

[Ron(UK)]

Post by TimPerry

Post by hank alrich

Post by Martin
Unfortunately, the usage of an archaic term to describe the filter has
caused some confusion amongst folks not familiar with the particular
gear.

Aaah, marketing... <g>
--
ha

amazing that its not called "the ultrafilter"

Or the Filterlizer

Ron

[Phildo]

From extensive experience multitrack recording, remixing and analyzing

If you've had all this "extensive experience" why is it you still know jack
shit about live sound Arny?

My best solution for handling noise is effective setup and use of the
scenes feature of my digital mixing console.

"Your" console? Don't you mean the console you have to volunteer to use
because that's the only way you get to do live sound?

Phildo

[Arny Krueger]

Post by Phildo

Post by Arny Krueger
From extensive experience multitrack recording, remixing
and analyzing live sound events I've got a lot of

If you've had all this "extensive experience" why is it
you still know jack shit about live sound Arny?

If you could read well Phildo, you'd realize that the scope
of my comments related to recording live sound events and
analyzing those recordings, not anything about doing live
sound itself.

Post by Phildo

Post by Arny Krueger
My best solution for handling noise is effective setup
and use of the scenes feature of my digital mixing
console.

"Your" console? Don't you mean the console you have to
volunteer to use because that's the only way you get to
do live sound?

I mean exactly the 02R96 console that was recommended,
installed, configured, and operated by my assistants and
myself.

Now Phildo, lets consider the PM1D (or is it PM5D?) s that
you use on there on ship.

(1) Phildo Did you personally and solely recommend the
purchase of that particular console and all of its
associated equipment and configuration?

(2) Phildo did you personally order the console - that is
directly work with the vendor to acquire it?

(3) Phildo, did you single-handedly do the work to emplace
it including any metalwork, or wood work or signal wiring
that might have been required?

(4) Phildo did you do all of the initial post-installation
checkout?

(5) Phildo, have you done all of the configuration of that
console, including all peripheral interfacing eq, dynamics
processing etc.?

(6) Phildo, did you design, specify, procure, and install
all of the related cabling and peripherals attached to tha
console including all of the 30-odd microphones?

...eagerly awaiting your response! ;-)

[TimPerry]

Post by Martin
Is the response flat with the filter out?

measures -1 dB @ 20 Hz referenced to 100 Hz. this is at the low end of the
test set but i feel the tolerance is close enough to answer the question
under discussion.



Any idea if this is above or

Post by Martin
below typical LF noise produced by handling?

below; as another poster indicated this is for low freq stuff like
vibrations coupled through a mic stand.

Does your filter

Post by Martin
effectively cut this noise?

i mostly deal with people who know how to hold a mic... the ones who don't i
provide floor stands, desk stands, or spring loaded mic arms with shock
mounted microphones (studio). for those occasions where handling noise is a
problem, some coaching is usually sufficient.


I don't have any calibrated frequency

Post by Martin
source to quantify my rolloff.
Martiner

use any variable oscillator whether a stand alone unit or a computer or
recorded tone on a CD or other recorded medium. follow with an amplifier
capable of boosting the signal to about 0 dB preferably more. follow this
with a fixed balanced attenuater (like a H-pad) to bring the levels down to
mic level. probably about 40 dB. place audio voltmeter before the pad. as
you adjust the oscillator adjust amplifier gain to mach whatever reference
level you have chosen.

adjust the above plan depending on the equipment and features you have
available. there is a lot of used ex-telephone company equipment on the
market that makes dandy test sets for sound equipment.

alternatively a pink noise generator to the input of the device under test
with a real time analyzer (or a computer running a RTA program) may prove
sufficient for your needs.

[Martin]

Thanks Tim, for some good data. If I can get Arny's suggestion working
to measure my frequency response, then I'll have your data for
comparison with my own unit.

Sounds like even if my box is working correctly, the range of signal
I'm concerned with may pass the filter anyway, but it's good to
quantify this.

Someone mentioned that SM58s don't pick up much handling noise - I
haven't found this to be true. They are not noticeably better
regarding conducted microphonics than some cheap Samson R-21s that I
have as backup. I've heard that the SM58 "beta" mics have improved
element isolation, perhaps the poster was thinking of those.

best regards,

Martin

Post by TimPerry

Post by Martin
Is the response flat with the filter out?

test set but i feel the tolerance is close enough to answer the question
under discussion.
Any idea if this is above or

Post by Martin
below typical LF noise produced by handling?

below; as another poster indicated this is for low freq stuff like
vibrations coupled through a mic stand.
Does your filter

Post by Martin
effectively cut this noise?

i mostly deal with people who know how to hold a mic... the ones who don't i
provide floor stands, desk stands, or spring loaded mic arms with shock
mounted microphones (studio). for those occasions where handling noise is a
problem, some coaching is usually sufficient.
I don't have any calibrated frequency

Post by Martin
source to quantify my rolloff.
Martiner

use any variable oscillator whether a stand alone unit or a computer or
recorded tone on a CD or other recorded medium. follow with an amplifier
capable of boosting the signal to about 0 dB preferably more. follow this
with a fixed balanced attenuater (like a H-pad) to bring the levels down to
mic level. probably about 40 dB. place audio voltmeter before the pad. as
you adjust the oscillator adjust amplifier gain to mach whatever reference
level you have chosen.
adjust the above plan depending on the equipment and features you have
available. there is a lot of used ex-telephone company equipment on the
market that makes dandy test sets for sound equipment.
alternatively a pink noise generator to the input of the device under test
with a real time analyzer (or a computer running a RTA program) may prove
sufficient for your needs.

[TimPerry]

Post by Martin
Thanks Tim, for some good data. If I can get Arny's suggestion working
to measure my frequency response, then I'll have your data for
comparison with my own unit.
Sounds like even if my box is working correctly, the range of signal
I'm concerned with may pass the filter anyway, but it's good to
quantify this.
Someone mentioned that SM58s don't pick up much handling noise - I
haven't found this to be true. They are not noticeably better
regarding conducted microphonics than some cheap Samson R-21s that I
have as backup.

you comment sparked an interest so i flipped open the nearest mic case and
popped a 58 into a mixer. holding the mic with thumb and index finger i
"scrunched" the mic by tapping and moving the remaining fingers along the
body. then speaking a standard "check 1,2" i established a SSR (signal to
scrunch ratio) by watching peak and VU meters and listening on the monitors.
i arbitrarily assigned a SSR of 5 to the 58 and then compared to other
assorted mics on a scale of 10 being the best (kind of like the scrunch
Olympics) and 1 being scrunch = speech output or the worst. i was
surprised at some of the results.

SM 58 - 5.0
SM 57 - 5.5
Shure BG 2.1 - 0.8 (schrunch louder then signal)
Audix vx-10 - 8.5
Audix om-6 - 8
Audio Technica MB300L - 4
Senheiser e 845 - 4
AKG D590s - 4
AKG D1000E (switch in broad) - 5
Audio Technica ATR 40 - 5
Crown CM 200A - 9.8
Senheiser MD 735 - 1
Behringer ECM 8000 - 9.9 (scrunch almost non existant)
unknown make (Goldline?) condenser omni ref mic - 9.5
Audix OM-5 - 8
Audix OM-2 - 8
Audio2000's APM1066 - 9 (i bought this for $20 in case i needed something
to throw)
Shure PG 81 - 9.5
Audio Technica MB 4000C - 4.5
EV RE20 - 2 (LF sw on)
Sennheiser MD-421U - 2 (set to M)
Sennheiser MD-441U - 1 (set to B)
Rode NT 5 - 3
Shure SM 81 - 9 (0 db attn)
Sennheiser e602 - 2
AKG d112 - 0.5
Audio Technica kick/tom - 0.5
Audix D-6 - 1
Audix ADX-51 - 9 (set 0 dB and flat)

OK so i got carried away comparing other then hand vocal mics but i'm easily
amused.

the APM1066 has a tight cardoid pattern that will probably give you problems
with armatures who cannot stay on mic. likewise the Audix OM series.

note: the SSR test is a subjective evaluation is not to be confused with lab
measurements. it is safe to try this at home :)

i think for general karaoke i'd go with SM-58

Post by Martin
I've heard that the SM58 "beta" mics have improved
element isolation, perhaps the poster was thinking of those.
best regards,
Martin

[Martin]

Post by TimPerry

Post by Martin
Thanks Tim, for some good data. If I can get Arny's suggestion working
to measure my frequency response, then I'll have your data for
comparison with my own unit.
Sounds like even if my box is working correctly, the range of signal
I'm concerned with may pass the filter anyway, but it's good to
quantify this.
Someone mentioned that SM58s don't pick up much handling noise - I
haven't found this to be true. They are not noticeably better
regarding conducted microphonics than some cheap Samson R-21s that I
have as backup.

you comment sparked an interest so i flipped open the nearest mic case and
popped a 58 into a mixer. holding the mic with thumb and index finger i
"scrunched" the mic by tapping and moving the remaining fingers along the
body. then speaking a standard "check 1,2" i established a SSR (signal to
scrunch ratio) by watching peak and VU meters and listening on the monitors.
i arbitrarily assigned a SSR of 5 to the 58 and then compared to other
assorted mics on a scale of 10 being the best (kind of like the scrunch
Olympics) and 1 being scrunch = speech output or the worst. i was
surprised at some of the results.
SM 58 - 5.0
SM 57 - 5.5
Shure BG 2.1 - 0.8 (schrunch louder then signal)
Audix vx-10 - 8.5
Audix om-6 - 8
Audio Technica MB300L - 4
Senheiser e 845 - 4
AKG D590s - 4
AKG D1000E (switch in broad) - 5
Audio Technica ATR 40 - 5
Crown CM 200A - 9.8
Senheiser MD 735 - 1
Behringer ECM 8000 - 9.9 (scrunch almost non existant)
unknown make (Goldline?) condenser omni ref mic - 9.5
Audix OM-5 - 8
Audix OM-2 - 8
Audio2000's APM1066 - 9 (i bought this for $20 in case i needed something
to throw)
Shure PG 81 - 9.5
Audio Technica MB 4000C - 4.5
EV RE20 - 2 (LF sw on)
Sennheiser MD-421U - 2 (set to M)
Sennheiser MD-441U - 1 (set to B)
Rode NT 5 - 3
Shure SM 81 - 9 (0 db attn)
Sennheiser e602 - 2
AKG d112 - 0.5
Audio Technica kick/tom - 0.5
Audix D-6 - 1
Audix ADX-51 - 9 (set 0 dB and flat)
OK so i got carried away comparing other then hand vocal mics but i'm easily
amused.
the APM1066 has a tight cardoid pattern that will probably give you problems
with armatures who cannot stay on mic. likewise the Audix OM series.
note: the SSR test is a subjective evaluation is not to be confused with lab
measurements. it is safe to try this at home :)
i think for general karaoke i'd go with SM-58

Post by Martin
I've heard that the SM58 "beta" mics have improved
element isolation, perhaps the poster was thinking of those.
best regards,
Martin

Tim,

That's very interesting data, though subjective. In my situation,
where untrained persons will be arbitrarily deciding to adjust the mic
during their performances or even remove/insert it from the holding
clip while singing, I might do well to investigate your higher-ranking
samples.

Many of them I've never heard of - which of that sample, rated 5 or
above, are considered good live vocal mics and also have street prices
of $100 or less? Obviously I can research the prices, but I don't know
much about the reputation of the gear. I noticed that the $50
Behringer, which you scored as a 9.9, is a "measurement microphone" and
probably not suitable for live vocals. But then I don't really know.

Certainly it looks as if the Audix OM-2 should be considered, assuming
it's a good vocal mic, as it's price is at or below the SM-58 and your
test shows it to have superior isolation.

The SM-58s I'm currently using cost $99 apiece.

best regards,

Martin

[TimPerry]

Post by Martin
Tim,
That's very interesting data, though subjective. In my situation,
where untrained persons will be arbitrarily deciding to adjust the mic
during their performances or even remove/insert it from the holding
clip while singing, I might do well to investigate your higher-ranking
samples.
Many of them I've never heard of - which of that sample, rated 5 or
above, are considered good live vocal mics and also have street prices
of $100 or less? Obviously I can research the prices, but I don't know
much about the reputation of the gear. I noticed that the $50
Behringer, which you scored as a 9.9, is a "measurement microphone" and
probably not suitable for live vocals. But then I don't really know.

correct.

in part i was checking mics for an upcoming show.

Post by Martin
Certainly it looks as if the Audix OM-2 should be considered, assuming
it's a good vocal mic, as it's price is at or below the SM-58 and your
test shows it to have superior isolation.

like all the OM series this is a hyper carotid pattern mic. great for pro
and semi-pro talent. not so great for amateurs.

Post by Martin
The SM-58s I'm currently using cost $99 apiece.
best regards,
Martin

best option: keep eye on mic and when singer starts to remove from clip pot
down mic.

other option: use butterfly type mic clip to minimize insert/removal noise

other option: use headset mic (look Garth, no hands!)

other option: glue mic to clip, glue clip to stand, nail stand to floor.

other option: web search for CLRN16 or rubberneck mic stand.


of my current collection, if someone made me do a bar type karaoke gig
again, i would take the MB4000C condensers with an added windscreen. they
sound great and at $69 if one got wrecked i wouldn't be as upset.

[Bob Howes]

Post by TimPerry
with the runble filter in. EQ sw off and EQ pots at neutral.

A couple of things on this one. First, the SM58 is features relatively low
handling noise before you start applying filters.

Second, your "tap the mic" test will be introducing frequencies much higher
than would normally be considered rumble. You couldn't filter these without
affecting the vocals.

Bob

[Phildo]

Post by Martin
Would someone else who owns the PMX-2000 please repeat my experiment,
and tell me if their rumble filter seems to be effective? I'd like to
know whether my specific unit is broken, or if perhaps it's just a bad
design with the cutoff not properly set.

Try and get hold of a copy of the Alan Parsons test CD and try the filter on
some of the low end test tones on that CD. It will soon tell you if it's
working or not.

Remember you need speakers that will reproduce those frequencies in the
first place. Unless you are using decent subs you probably won't hear much
effect from the filter anyway.

Phildo