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Mackie SRM350: Early Units Warning

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Anonymous
October 9, 2004 10:08:55 PM

Archived from groups: rec.audio.pro (More info?)

Public Service Announcment

I have here for audition a brand new pair of Mackie SRM350's. This pair
exhibits hum, buzz and hiss. This problem is known to Mackie who say it
is happening with only a few of the early units. Mackie says this is not
the way these are supposed to work, and that they are working on a fix.
More information should come along real soon now.

In the meantime my sincere advice is that one not order these
long-distance, but only purchase units that one has heard and that do
not emit noise in the absence of signal. This noise level is not subject
to alteration by the level control.

Another issue, and one probably less amenable to a quick fix, is the
"quality" of the so-called "mic preamp" in the SRM350. While the manual
claims "Since the SRM350 incorporates Mackie's world-class low-noise mic
preamp technology...<blah blah omitted in the interest of reality>" this
thing is the worst performing "mic preamp" I have ever met. There is
absolutely no excuse for calling this a "mic preamp". The noise level is
completely outrageous. I hope Mackie doesn't sell any of these to the
wrong kind of lawyer who imagined he/she would get an actual mic preamp.

Hopefully the hum, buzz and hiss will get medicine. The mic preamp will
need to be ignored.

--
ha
Anonymous
October 9, 2004 10:08:56 PM

Archived from groups: rec.audio.pro (More info?)

In article <1gldy56.1nmywyb773jauN%walkinay@thegrid.net> walkinay@thegrid.net writes:

> Hopefully the hum, buzz and hiss will get medicine. The mic preamp will
> need to be ignored.

I wonder if they're related, like perhaps through the power supply.
It's not that hard to build a functional mic preamp if you have a good
power supply, and you need a good power supply to make a decent power
amplifier.



--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
Anonymous
October 10, 2004 1:28:36 PM

Archived from groups: rec.audio.pro (More info?)

"hank alrich" <walkinay@thegrid.net> wrote in message
news:1gldy56.1nmywyb773jauN%walkinay@thegrid.net...
t an actual mic preamp.
>
> Hopefully the hum, buzz and hiss will get medicine. The mic preamp will
> need to be ignored.


So you don't think the mic preamp noise is related to the other noise ?

geoff
Related resources
Anonymous
October 10, 2004 5:28:32 PM

Archived from groups: rec.audio.pro (More info?)

"hank alrich" <walkinay@thegrid.net> wrote :
> Public Service Announcment

> not emit noise in the absence of signal. This noise level is not subject
> to alteration by the level control.

I measured the SRM50 noise and found that the residual is 44 dBC at 250mm on
axis with the Mackie blue logo in a room with a residual noise of 37 dBC.
The principal hum and buzz components are at 60, 180, 240, 300, 480, 540,
660, 780, 1020, 1260 Hz. The broadband noise starts at around 80 Hz and goes
to 16 KHz with a some broad dips centered on 250 Hz and again at 2 KHz. It
is independent of the level control as Hank stated. Measurements were
performed with ACO Pacific 4012+7046 mic with a Great River MP-2 for gain
stage. Calibration via B&K 4231 at 1 and 10 Pascals. SIAsoft RTA for
spectrum and SPL measurements.

> Another issue, and one probably less amenable to a quick fix, is the
> "quality" of the so-called "mic preamp" in the SRM350. While the manual

At what level setting does the mic preamp noise get above the residual noise
on the units you have? The units here don't become noticable until 2 o
clock. At 3 o clock feedback becomes more of an issue in the room I'm using
today. Tested with sm57 and om5 mics and 160 ohm termination resistor (which
of course doesn't have feedback issues - the mic preamp noise gets real ugly
at 5 o clock and on up to max gain with the resistor).

> Hopefully the hum, buzz and hiss will get medicine. The mic preamp will
> need to be ignored.

Unless they fix the mic preamp noise too.

On the plus side, the SRM350 is smaller and lighter than similar units,
packs a lot of sound which remains pretty decent even at 110 dBC average at
1 meter. The sound falls off more evenly as one moves around to the back
side of the speaker and doesn't become as woofy as some others. I think the
unit starts to light up around 85 dBC at 1 meter. Below it seems a little
closed-in to me. I really appreciate the sound for the weight, having a back
that's not as strong as it once was. The spectrum is fairly flat with a bit
of a crossover dip around 1800 Hz. The midrange sounds very good to me,
though this isn't a junior EAW FR159z (which is awesome but heavy - you get
what you pay for).

bobs

Bob Smith
BS Studios
we organize chaos
http://www.bsstudios.com
Anonymous
October 10, 2004 7:07:14 PM

Archived from groups: rec.audio.pro (More info?)

Mackie's web site says "coming soon" for the SRM350. Is it possible
they've stopped production to fix these problems? Or is it just an
out-of-date web site?

--
- rick http://www.cfcl.com/~rick/
Rick Auricchio Macs Only: Macintosh support rick@cfcl.com
I acknowledge the existence of a higher power, and have therefore installed
surge suppressors.
Anonymous
October 10, 2004 11:11:14 PM

Archived from groups: rec.audio.pro (More info?)

Eric K. Weber wrote:

> If you want to complain about false advertising, how about the web site pdf
> that prominently said made in USA...... when mine arrived the made in USA
> was covered with a stick on made in China..... The unit I received is a
> little on the noisy side...

I think it's important not to settle for the noise. I've had high hopes
for these but if they don't meet those expectations reasonably well I
have no problem telling Mackie "No, thanks, these are _yours_, not mine"
and looking elsewhere.

--
ha
Anonymous
October 10, 2004 11:29:32 PM

Archived from groups: rec.audio.pro (More info?)

Mike Rivers wrote:

> walkinay writes:

> > Hopefully the hum, buzz and hiss will get medicine. The mic preamp will
> > need to be ignored.

> I wonder if they're related, like perhaps through the power supply.

I don't think so because to my ear the noise signature is quite
different. I do think the hum/buzz/hiss noise is power supply related,
and maybe amp related, too.

> It's not that hard to build a functional mic preamp if you have a good
> power supply, and you need a good power supply to make a decent power
> amplifier.

Had they just done as well as they did with the pres in a 1202 I'd have
no comment about the "mic preamp".

<j>

Maybe they should have hired somebody from Behringer to help them
reverse engineer the 1202 mic pre.

</j>

In fact, the mic preamp in the under-seventy-US$ list Beri UB 508 kills
this Mackie mislabeled atrocity.

--
ha
Anonymous
October 11, 2004 2:30:41 AM

Archived from groups: rec.audio.pro (More info?)

Rick Auricchio wrote:

> Mackie's web site says "coming soon" for the SRM350. Is it possible
> they've stopped production to fix these problems? Or is it just an
> out-of-date web site?

They didn't want to break with tradition, so they've had the site saying
that since at least back in April this year.

Plus, download the .pdf's and see the Combo jack. There is no combo jack
now, nevermind the manual. I wonder if price competition means rationing
brains.

The shift in the dollar/Euro rate has influenced choices of shipment
destinations in the macro sense. Still, they've been shipping long
enough to change the website, if anyone at Mackie is paying attention.

--
ha
Anonymous
October 11, 2004 3:30:39 AM

Archived from groups: rec.audio.pro (More info?)

Bob Smith wrote:

> I measured the SRM50 noise and found that the residual is 44 dBC at 250mm on
> axis with the Mackie blue logo in a room with a residual noise of 37 dBC.

Is dBC C-weighted noise? What's the reference, C-weighted
white at 2e-5 Pa RMS after the filter?


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein
Anonymous
October 11, 2004 1:13:11 PM

Archived from groups: rec.audio.pro (More info?)

"Bob Cain" <arcane@arcanemethods.com> wrote:
>
>
> Bob Smith wrote:
>
> > I measured the SRM50 noise and found that the residual is 44 dBC at
250mm on
> > axis with the Mackie blue logo in a room with a residual noise of 37
dBC.
>
> Is dBC C-weighted noise? What's the reference, C-weighted
> white at 2e-5 Pa RMS after the filter?

A very good question. I'm also surprised that no one has asked for the A
weighted measurements which would be more representative of the perceived
annoyance factor if the SRM350 was used in a quiet ambient situation.

To answer your question:

Gain staging set for 0 dB FS = 100 dBC SPL ref 20 uPa, measured - 6dB FS at
1 Pa from the B&K4231 mic spl calibrator
Unbalanced input of the Great River MP-2 terminated with 75 ohms at the end
of the cable where the measurement mic power supply attaches (it's
unbalanced, a BNC connector on the ACO Pacific PS9200)
Residual electrical noise:
8.9 dB SPL unweighted
4.2 dB C
4.8 dB A
Spot frequencies for broadband noise
16 Hz -38 dB SPL ref 20 uPa (that's minus 38 dB SPL)
200 Hz -28 dB
20KHz -8 dB
Mains noise above the broadband noise:
60 Hz -14 dB SPL ref 20 uPa (that's minus 14 dB SPL)
120 Hz -12 dB
180 Hz -10 dB
240 Hz -18 dB
300 Hz -13 dB
420 Hz -17 dB

As for the A & C weighted SRM350 residual noise measurements:
SRM350 41 dBA 44 dBC
room 20 dBA 37 dBC

bobs

Bob Smith
BS Studios
we organize chaos
http://www.bsstudios.com
Anonymous
October 11, 2004 3:29:30 PM

Archived from groups: rec.audio.pro (More info?)

"Bob Smith"


> I measured the SRM50 noise and found that the residual is 44 dBC at 250mm
> on
> axis with the Mackie blue logo in a room with a residual noise of 37 dBC.


** So at 1 meter distance the noise falls by another 10 dB to 34 dB SPL
and is then well below that of a quiet room. That suggests the s/n of the
amplification (inc electronic x-over ) used inside the unit is about 90 dB,
unweighted.





.............. Phil
Anonymous
October 23, 2004 7:15:33 PM

Archived from groups: rec.audio.pro (More info?)

Mine will be returning for the same reason.... when I got a chance to test
them in the room they were to be used in the noise was found to be annoying
and easy to hear at 20 feet from the speaker.

Also the false advertising about made in USA, when they are actually made in
Red China....

Rgds:
Eric

"hank alrich" <walkinay@thegrid.net> wrote in message
news:1gldy56.1nmywyb773jauN%walkinay@thegrid.net...
> Public Service Announcment
>
> I have here for audition a brand new pair of Mackie SRM350's. This pair
> exhibits hum, buzz and hiss. This problem is known to Mackie who say it
> is happening with only a few of the early units. Mackie says this is not
> the way these are supposed to work, and that they are working on a fix.
> More information should come along real soon now.
>
> In the meantime my sincere advice is that one not order these
> long-distance, but only purchase units that one has heard and that do
> not emit noise in the absence of signal. This noise level is not subject
> to alteration by the level control.
>
> Another issue, and one probably less amenable to a quick fix, is the
> "quality" of the so-called "mic preamp" in the SRM350. While the manual
> claims "Since the SRM350 incorporates Mackie's world-class low-noise mic
> preamp technology...<blah blah omitted in the interest of reality>" this
> thing is the worst performing "mic preamp" I have ever met. There is
> absolutely no excuse for calling this a "mic preamp". The noise level is
> completely outrageous. I hope Mackie doesn't sell any of these to the
> wrong kind of lawyer who imagined he/she would get an actual mic preamp.
>
> Hopefully the hum, buzz and hiss will get medicine. The mic preamp will
> need to be ignored.
>
> --
> ha
!