QSC RMX 2450 not working

[Tom Hole]

Before I run this off to the dealer, I wanted to check with the
experts here.

I have a QSC RMX 2450 that I run in bridge mono to 2 Yorkville LS1208
subs (1200 watts, 8 ohms each). At the end of the gig 2 weeks ago, I
was running them hard with moderate clipping on the 2450. The 2450
shut down, so I switched to my backup amp and figured the 2450 would
come out of whatever protect it went into and all would be good. I
checked the 2450 and it is not behaving. It powers up and all looks
well. I apply a signal and turn up ch 1 and the ch1 signal light
comes on as expected. The ch2 signal light comes on, too, but so does
the ch2 clip light and this is with the ch2 input turned down as it
should be. So, I switch to stereo, unbridged and apply a signal to
ch1. All is well on ch1. Apply the signal to ch2 and turn up the
input about 1/8 turn and the signal light comes on as does the clip
light (solid). No noise from ch2 output.

Seems as though I may have offended the electronic sensibility of ch2.
I have pushed the 2450 to shut down once before in 2 years. It
recovered nicely after the first time and it was pushed much harder
that time. I would not have expected it to crap out on this occasion,
but alas, I was wrong.

So, any quick checks for a moderately untaleneted electrical engineer
to conduct or should I leave it to the local dealer for service?

Many thanks for the help,

Tom

BTW, I am buying a Behringer EP2500 so I can run one 1208 on each big
amp (after I get this 2450 fixed). I get to open them both up and see
how the guts compare.

[Jan Otto]

The Behringer EP2500 is apparently a 100% copy the QSC RMX 2450 with minor
circuit changes/improvements ?. I have heard of clipping protection failures
especially on the RMX 2450 from sound engineer friends. Unfortunately I
cannot give you info on how to fix the problem.

Jan Otto

Post by Tom Hole
Before I run this off to the dealer, I wanted to check with the
experts here.
I have a QSC RMX 2450 that I run in bridge mono to 2 Yorkville LS1208
subs (1200 watts, 8 ohms each). At the end of the gig 2 weeks ago, I
was running them hard with moderate clipping on the 2450. The 2450
shut down, so I switched to my backup amp and figured the 2450 would
come out of whatever protect it went into and all would be good. I
checked the 2450 and it is not behaving. It powers up and all looks
well. I apply a signal and turn up ch 1 and the ch1 signal light
comes on as expected. The ch2 signal light comes on, too, but so does
the ch2 clip light and this is with the ch2 input turned down as it
should be. So, I switch to stereo, unbridged and apply a signal to
ch1. All is well on ch1. Apply the signal to ch2 and turn up the
input about 1/8 turn and the signal light comes on as does the clip
light (solid). No noise from ch2 output.
Seems as though I may have offended the electronic sensibility of ch2.
I have pushed the 2450 to shut down once before in 2 years. It
recovered nicely after the first time and it was pushed much harder
that time. I would not have expected it to crap out on this occasion,
but alas, I was wrong.
So, any quick checks for a moderately untaleneted electrical engineer
to conduct or should I leave it to the local dealer for service?
Many thanks for the help,
Tom
BTW, I am buying a Behringer EP2500 so I can run one 1208 on each big
amp (after I get this 2450 fixed). I get to open them both up and see
how the guts compare.

[liquidator]

Post by Jan Otto
The Behringer EP2500 is apparently a 100% copy the QSC RMX 2450 with minor
circuit changes/improvements ?.

Only to stupid people. In the real world they are not the same. Get your
facts straight.

[Tom Hole]

Post by liquidator

Post by Jan Otto
The Behringer EP2500 is apparently a 100% copy the QSC RMX 2450 with minor
circuit changes/improvements ?.

Only to stupid people. In the real world they are not the same. Get your
facts straight.

I get to find out in 2 weeks or so.

Tom

[liquidator]

Post by Tom Hole
I get to find out in 2 weeks or so.

Looking at pictures they are not the same amp. 100% copy is ridiculous.Parts
are in different places. What we need is schematics to compare.

[Tom Hole]

Post by liquidator

Post by Tom Hole
I get to find out in 2 weeks or so.

Looking at pictures they are not the same amp. 100% copy is

ridiculous.Parts

Post by liquidator
are in different places. What we need is schematics to compare.

Personally, I am very happy that a company has offered exactly what I need
at a reasonable price. I'll judge it by how it performs and holds up. I
still have a Behringer 2x31 that just gets me by as a backup monitor eq.
The Behringer SuperX crossover has done an admirable job as my aux fed subs
xover. I just ordered a full bag of digital Behringer (DDX3216, ADT1616,
ADA8000) and if it performs well and holds up, I wouldn't mind if it said
"Cheap Chinese Import" right on the front. I can't afford (nor do I really
need Midas), so I go with what works (but I love working on one when we play
at the bigger clubs ;). Sometimes that is affordable, sometimes not.
Should be fun playing with the digital stuff.

Tom

[liquidator]

Post by Tom Hole
Personally, I am very happy that a company has offered exactly what I need
at a reasonable price. I'll judge it by how it performs and holds up.

A few months back I bench tested one of the Behringers and posted my results
here. the specs are honest. I was surprised,at the price they are as good as
any pro amps that were around just a few years ago.

Post by Tom Hole
Should be fun playing with the digital stuff.

I agree. I hardly ever run sound anymore. I do miss it a lot.

[Arny Krueger]

Post by liquidator
A few months back I bench tested one of the Behringers and posted my
results here. the specs are honest. I was surprised,at the price they
are as good as any pro amps that were around just a few years ago.

More details? Searching google based on what you've said so far finds said
test results to be elusive.

[liquidator]

Post by Arny Krueger

Post by liquidator
A few months back I bench tested one of the Behringers and posted my
results here. the specs are honest. I was surprised,at the price they
are as good as any pro amps that were around just a few years ago.

More details? Searching google based on what you've said so far finds said
test results to be elusive.

Hi Arny- I didn't start out to do a full scale review, just to satisfy
myself they would be adequate for less demanding apps. I essentially
confrirmed the specs and not much more other than playing with the
protection circuits. I only had access to the unit for a couple hours and
wasn't able to devote all that time to the amp. Intermittent shorts were
ignored by the unit, sustained shorts shut it down without damage. I
consider it a solid "b" grade unit. For weekend warriors and small pubs it's
more than adequate.

I looked through my "sent items" folder but apparently I have cleaned it out
since then. Sorry.

[Lord Valve]

Post by liquidator

Post by liquidator

Post by Tom Hole
I get to find out in 2 weeks or so.

Looking at pictures they are not the same amp. 100% copy is

ridiculous.Parts

Post by liquidator
are in different places. What we need is schematics to compare.

Personally, I am very happy that a company has offered exactly what I need
at a reasonable price. I'll judge it by how it performs and holds up. I
still have a Behringer 2x31 that just gets me by as a backup monitor eq.
The Behringer SuperX crossover has done an admirable job as my aux fed subs
xover. I just ordered a full bag of digital Behringer (DDX3216, ADT1616,
ADA8000) and if it performs well and holds up, I wouldn't mind if it said
"Cheap Chinese Import" right on the front. I can't afford (nor do I really
need Midas), so I go with what works (but I love working on one when we play
at the bigger clubs ;). Sometimes that is affordable, sometimes not.
Should be fun playing with the digital stuff.
Tom

I've been waiting for about two years for Phildo and the rest
of the recently-converted Behringer Jihadis to bow in my
direction and offer me some heartfelt "We're not worthy"(s)
for having been the first here to observe that Behringer's
price/performance ratio is excellent.

It's good to be the Lord. ;-) Worship me, pukes - I rule,
and y'all know it. It won't hurt long, go ahead. ;-)

Lord Valve
Audio Pioneer

[George]

Post by Jan Otto
The Behringer EP2500 is apparently a 100% copy the QSC RMX 2450
Jan Otto

an please quote your source for this "information" this has been
explored in depth here and we have concluded that the amps are not even
vaugly related
George

[Ray Abbitt]

Post by George

Post by Jan Otto
The Behringer EP2500 is apparently a 100% copy the QSC RMX 2450
Jan Otto

an please quote your source for this "information" this has been
explored in depth here and we have concluded that the amps are not even
vaugly related

Why don't you just ignore the troll? The original poster asked about
help with an RMX 2450. He didn't mention Behringer at all. There was
no reason to bring it up at all and even less reason to answer him.

But now that you have brought it up, careful how you use the word "we"
because as far as I can tell there was no conclusion reached because
nobody ever has seen the two side by side and (apparently) nobody has
ever seen the schematic for the Behringer.

-ray

[George]

Post by Ray Abbitt

Post by George

Post by Jan Otto
The Behringer EP2500 is apparently a 100% copy the QSC RMX 2450
Jan Otto

an please quote your source for this "information" this has been
explored in depth here and we have concluded that the amps are not even
vaugly related

Why don't you just ignore the troll? The original poster asked about
help with an RMX 2450. He didn't mention Behringer at all. There was
no reason to bring it up at all and even less reason to answer him.
But now that you have brought it up, careful how you use the word "we"
because as far as I can tell there was no conclusion reached because
nobody ever has seen the two side by side and (apparently) nobody has
ever seen the schematic for the Behringer.
-ray

I use the word "we" beacuse many folks were involved in the discussion,
and none could substantiate any similarity between the products
dozens of people described the diffrencves but not one accuser could
find a single point to offer validity to thier claim
the Behringer thing has been examined and re-examined in hundreds if not
thousnads of post and the closes they got to any behringer using similar
though not identical technology was a 15 year old claim by Aphex
Mackies claim was laughed out of the courts and makie was lucky that
behringer did not sue them for slander
both these amp have been for sale for years if there was a "100%copy"
claim of substance it would have been brought to the courts
I have personally spoken with principals at both Behringer and QSC and
both have told me "There is nothing to this vicious rumor"
I believe this qualifies as "we"
George

[liquidator]

Post by Ray Abbitt

Post by George

Post by Jan Otto
The Behringer EP2500 is apparently a 100% copy the QSC RMX 2450
Jan Otto

an please quote your source for this "information" this has been
explored in depth here and we have concluded that the amps are not even
vaugly related

Why don't you just ignore the troll? The original poster asked about
help with an RMX 2450. He didn't mention Behringer at all.

Hi Ray- actually the OP did mention he was going to buy a behringer.

Post by Ray Abbitt
But now that you have brought it up, careful how you use the word "we"
because as far as I can tell there was no conclusion reached because
nobody ever has seen the two side by side and (apparently) nobody has
ever seen the schematic for the Behringer.

Arny did post pictures of both amps, showing components in different places.
Obvious they are not the same amp. However the jury is still out till we see
schematics. My gut feeling is they are no more related than any 2 amps at
random. QSC and Behringer reinforce this as George mentions.

[Richard Freeman]

Post by Jan Otto
The Behringer EP2500 is apparently a 100% copy the QSC RMX 2450 with minor
circuit changes/improvements

The Circuit board Layout is complately diferent, The Mechanical layout is
different, many of the components are different and the Topology is slightly
different. other than that they are exactly the same amp ;-)

Regards
Richard Freeman

[Dale C]

Post by Tom Hole
Before I run this off to the dealer, I wanted to check with the
experts here.

Im NOT an expert, but have a suggestion

Post by Tom Hole
I apply a signal and turn up ch 1 and the ch1 signal light
comes on as expected. The ch2 signal light comes on, too, but so does
the ch2 clip light and this is with the ch2 input turned down as it
should be. So, I switch to stereo, unbridged and apply a signal to
ch1. All is well on ch1. Apply the signal to ch2 and turn up the
input about 1/8 turn and the signal light comes on as does the clip
light (solid). No noise from ch2 output.

This happened to me one day. Thought the amp went out. Found a bad cable to
the speaker. Phew!

Dale

[Tom Hole]

Post by Dale C

Post by Tom Hole
Before I run this off to the dealer, I wanted to check with the
experts here.

Im NOT an expert, but have a suggestion

Post by Tom Hole
I apply a signal and turn up ch 1 and the ch1 signal light
comes on as expected. The ch2 signal light comes on, too, but so does
the ch2 clip light and this is with the ch2 input turned down as it
should be. So, I switch to stereo, unbridged and apply a signal to
ch1. All is well on ch1. Apply the signal to ch2 and turn up the
input about 1/8 turn and the signal light comes on as does the clip
light (solid). No noise from ch2 output.

This happened to me one day. Thought the amp went out. Found a bad cable to
the speaker. Phew!
Dale

Dale,

Unfortunately, it behaves badly with or without a load. Drat.

Tom

[Dave Walsh]

Post by Tom Hole

Post by Dale C

Post by Tom Hole
Before I run this off to the dealer, I wanted to check with the
experts here.

Im NOT an expert, but have a suggestion

Post by Tom Hole
I apply a signal and turn up ch 1 and the ch1 signal light
comes on as expected. The ch2 signal light comes on, too, but so does
the ch2 clip light and this is with the ch2 input turned down as it
should be. So, I switch to stereo, unbridged and apply a signal to
ch1. All is well on ch1. Apply the signal to ch2 and turn up the
input about 1/8 turn and the signal light comes on as does the clip
light (solid). No noise from ch2 output.

This happened to me one day. Thought the amp went out. Found a bad cable

to

Post by Dale C
the speaker. Phew!
Dale

Dale,
Unfortunately, it behaves badly with or without a load. Drat.
Tom

Bummer Tom,
Am still trying to figure out why those poeple debating the RMX vs Behringer
topic posted under your post. Perhaps its a case of 'I dont know the answer
to your question but heres some irrelevant information to show that I read
something on this board'.
Anyway, What do ya mean by moderate clipping???..I wouldnt be too happy to
see any amps clipping (yeah I know some manufacturers clip lights come on
upto 6db before clipping ). If ye need to drive the amp into clipping I
would recommend getting a bigger amp so you wont have to. Or are you one of
those many people out there that feel better when they see red
lights??..hehehe
Now also I know that there was a fix released for the 2450 soon after its
release, something about cooling fins touching each other, and not in a good
way. Been a while since we've used RMXs so cant remember exactly but Im sure
your dealer will know something about it.
The fact that its not comming out of clip means that there are damamged
components, probably on the output stage.
Stay outta the red man.
Glukk
Dave W.

[Tom Hole]

Post by Dave Walsh

Post by Tom Hole

Post by Dale C

Post by Tom Hole
Before I run this off to the dealer, I wanted to check with the
experts here.

Im NOT an expert, but have a suggestion

Post by Tom Hole
I apply a signal and turn up ch 1 and the ch1 signal light
comes on as expected. The ch2 signal light comes on, too, but so does
the ch2 clip light and this is with the ch2 input turned down as it
should be. So, I switch to stereo, unbridged and apply a signal to
ch1. All is well on ch1. Apply the signal to ch2 and turn up the
input about 1/8 turn and the signal light comes on as does the clip
light (solid). No noise from ch2 output.

This happened to me one day. Thought the amp went out. Found a bad cable

to

Post by Dale C
the speaker. Phew!
Dale

Dale,
Unfortunately, it behaves badly with or without a load. Drat.
Tom

Bummer Tom,
Am still trying to figure out why those poeple debating the RMX vs Behringer
topic posted under your post. Perhaps its a case of 'I dont know the answer
to your question but heres some irrelevant information to show that I read
something on this board'.
Anyway, What do ya mean by moderate clipping???..I wouldnt be too happy to
see any amps clipping (yeah I know some manufacturers clip lights come on
upto 6db before clipping ). If ye need to drive the amp into clipping I
would recommend getting a bigger amp so you wont have to. Or are you one of
those many people out there that feel better when they see red
lights??..hehehe
Now also I know that there was a fix released for the 2450 soon after its
release, something about cooling fins touching each other, and not in a good
way. Been a while since we've used RMXs so cant remember exactly but Im sure
your dealer will know something about it.
The fact that its not comming out of clip means that there are damamged
components, probably on the output stage.
Stay outta the red man.
Glukk
Dave W.

Dave,

Yeah, the 2450 was always working hard on the 1208's. I have been meaning
to add a 2450 for a while and put one on each 1208, but never got around to
it. Now I did. I'll get the 2450 fixed and keep one amp on each 1208 (1500
watts each) and keep them outa the red. Hopefully it won't be too expensive
a lesson.

Tom

[Lord Valve]

You have one or more shorted output transistors on channel 2.

LV

Post by Tom Hole
Before I run this off to the dealer, I wanted to check with the
experts here.
I have a QSC RMX 2450 that I run in bridge mono to 2 Yorkville LS1208
subs (1200 watts, 8 ohms each). At the end of the gig 2 weeks ago, I
was running them hard with moderate clipping on the 2450. The 2450
shut down, so I switched to my backup amp and figured the 2450 would
come out of whatever protect it went into and all would be good. I
checked the 2450 and it is not behaving. It powers up and all looks
well. I apply a signal and turn up ch 1 and the ch1 signal light
comes on as expected. The ch2 signal light comes on, too, but so does
the ch2 clip light and this is with the ch2 input turned down as it
should be. So, I switch to stereo, unbridged and apply a signal to
ch1. All is well on ch1. Apply the signal to ch2 and turn up the
input about 1/8 turn and the signal light comes on as does the clip
light (solid). No noise from ch2 output.
Seems as though I may have offended the electronic sensibility of ch2.
I have pushed the 2450 to shut down once before in 2 years. It
recovered nicely after the first time and it was pushed much harder
that time. I would not have expected it to crap out on this occasion,
but alas, I was wrong.
So, any quick checks for a moderately untaleneted electrical engineer
to conduct or should I leave it to the local dealer for service?
Many thanks for the help,
Tom
BTW, I am buying a Behringer EP2500 so I can run one 1208 on each big
amp (after I get this 2450 fixed). I get to open them both up and see
how the guts compare.

[Tom Hole]

Post by Lord Valve
You have one or more shorted output transistors on channel 2.
LV

That sounds not good. I'm going to call the local QSC dealer today and see
where this starts, $$$ wise.

Tom

[Analogeezer]

Post by Tom Hole

Post by Lord Valve
You have one or more shorted output transistors on channel 2.
LV

That sounds not good. I'm going to call the local QSC dealer today and see
where this starts, $$$ wise.
Tom

The last time I had this repaired on a CS-400 (about four years ago)
it generally ran about $65 and I'm in a high cost area (tech charges
run about that or more per hour).

That was four or five years ago though.

The other thing is the output transistors are very easy to get to on a
CS-400, I don't know about the RMX series.

I have heard they are hard to work on, but that could just be
hearsay...others on this group could probably weigh in with that.

Even though it's a cheap amp, QSC rep and resale value would be good
enough to get it fixed I would think.

Analogeezer

[Tom Hole]

Post by Tom Hole
Before I run this off to the dealer, I wanted to check with the
experts here.
I have a QSC RMX 2450 that I run in bridge mono to 2 Yorkville LS1208
subs (1200 watts, 8 ohms each). At the end of the gig 2 weeks ago, I
was running them hard with moderate clipping on the 2450. The 2450
shut down, so I switched to my backup amp and figured the 2450 would
come out of whatever protect it went into and all would be good. I
checked the 2450 and it is not behaving. It powers up and all looks
well. I apply a signal and turn up ch 1 and the ch1 signal light
comes on as expected. The ch2 signal light comes on, too, but so does
the ch2 clip light and this is with the ch2 input turned down as it
should be. So, I switch to stereo, unbridged and apply a signal to
ch1. All is well on ch1. Apply the signal to ch2 and turn up the
input about 1/8 turn and the signal light comes on as does the clip
light (solid). No noise from ch2 output.
Seems as though I may have offended the electronic sensibility of ch2.
I have pushed the 2450 to shut down once before in 2 years. It
recovered nicely after the first time and it was pushed much harder
that time. I would not have expected it to crap out on this occasion,
but alas, I was wrong.
So, any quick checks for a moderately untaleneted electrical engineer
to conduct or should I leave it to the local dealer for service?
Many thanks for the help,
Tom
BTW, I am buying a Behringer EP2500 so I can run one 1208 on each big
amp (after I get this 2450 fixed). I get to open them both up and see
how the guts compare.

Ok, I just got around to opening the 2450 and there was a blown 250v 20A
fuze on ch2. I replaced it and the amp appears to be up and running. Does
this sound reasonable? If so, I consider myself a lucky man.

Tom

[George]

Post by Tom Hole
Ok, I just got around to opening the 2450 and there was a blown 250v 20A
fuze on ch2. I replaced it and the amp appears to be up and running. Does
this sound reasonable? If so, I consider myself a lucky man.
Tom

blown fuses have been knowm to cause fail like symptoms
:-)
George

[Tom Hole]

Post by George

Post by Tom Hole
Ok, I just got around to opening the 2450 and there was a blown 250v 20A
fuze on ch2. I replaced it and the amp appears to be up and running.

Does

Post by George

Post by Tom Hole
this sound reasonable? If so, I consider myself a lucky man.
Tom

blown fuses have been knowm to cause fail like symptoms
:-)
George

Too bad that wasn't mentioned in any of the earlier posts. Good lesson
learned for me.

TOm

[George]

Post by Tom Hole

Post by George

Post by Tom Hole
Ok, I just got around to opening the 2450 and there was a blown 250v 20A
fuze on ch2. I replaced it and the amp appears to be up and running.

Does

Post by George

Post by Tom Hole
this sound reasonable? If so, I consider myself a lucky man.
Tom

blown fuses have been knowm to cause fail like symptoms
:-)
George

Too bad that wasn't mentioned in any of the earlier posts. Good lesson
learned for me.
TOm

I used to run big Carvers that would go through fuses when ever
impeadence dropped close to 2 ohms
luckily it was a external fuse holder
George

[Hubert Barth]

Post by George
I used to run big Carvers that would go through fuses when ever
impeadence dropped close to 2 ohms
luckily it was a external fuse holder

I have a PM 1.5.A where the mains fuse was blown. New fuse and running
up again.
I was suspecting that the amp had same malfunction and didn´t use it
since, but after this info I think it should be ok, probably just age.

Thanks.

[Pooh Bear]

Post by Tom Hole
Ok, I just got around to opening the 2450 and there was a blown 250v 20A
fuze on ch2. I replaced it and the amp appears to be up and running. Does
this sound reasonable?

That corresponds to the symptoms you mentioned.

Aren't there 2 fuses per channel ? Don't have the schematic readily to hand
sadly. If so, I would replace both of them.

Post by Tom Hole
If so, I consider myself a lucky man.

I would suggest activating the internal limiters - it's relatively unlikely to
happen again if you do that. Basically you were 'overdriving' the amp.

As fuses can 'fatigue' you might care to replace Ch1 fuse(s) too as it/they
will have had to carry the same current as Ch 2 in bridged mode.

Graham

[Tom Hole]

Post by Pooh Bear

Post by Tom Hole
Ok, I just got around to opening the 2450 and there was a blown 250v 20A
fuze on ch2. I replaced it and the amp appears to be up and running.

Does

Post by Pooh Bear

Post by Tom Hole
this sound reasonable?

That corresponds to the symptoms you mentioned.
Aren't there 2 fuses per channel ? Don't have the schematic readily to hand
sadly. If so, I would replace both of them.

Post by Tom Hole
If so, I consider myself a lucky man.

I would suggest activating the internal limiters - it's relatively unlikely to
happen again if you do that. Basically you were 'overdriving' the amp.
As fuses can 'fatigue' you might care to replace Ch1 fuse(s) too as it/they
will have had to carry the same current as Ch 2 in bridged mode.
Graham

Grahm,

I only saw one fuse per channel. I did have the internal limiters on. I
already re-racked the amp so I'll just keep some spare fuses in the gak box.
Thanks for the reply and help.

TOm

[Arny Krueger]

Post by Pooh Bear

Post by Tom Hole
Ok, I just got around to opening the 2450 and there was a blown 250v
20A fuze on ch2. I replaced it and the amp appears to be up and
running. Does this sound reasonable?

That corresponds to the symptoms you mentioned.
Aren't there 2 fuses per channel ?

I see only one.

Post by Pooh Bear
Don't have the schematic readily to hand sadly. If so, I would replace

both of them.

http://www.qscaudio.com/support/library/schems/rmx2450.pdf

[Chad Wahls]

Post by Tom Hole

Post by Tom Hole
Before I run this off to the dealer, I wanted to check with the
experts here.
I have a QSC RMX 2450 that I run in bridge mono to 2 Yorkville LS1208
subs (1200 watts, 8 ohms each). At the end of the gig 2 weeks ago, I
was running them hard with moderate clipping on the 2450. The 2450
shut down, so I switched to my backup amp and figured the 2450 would
come out of whatever protect it went into and all would be good. I
checked the 2450 and it is not behaving. It powers up and all looks
well. I apply a signal and turn up ch 1 and the ch1 signal light
comes on as expected. The ch2 signal light comes on, too, but so does
the ch2 clip light and this is with the ch2 input turned down as it
should be. So, I switch to stereo, unbridged and apply a signal to
ch1. All is well on ch1. Apply the signal to ch2 and turn up the
input about 1/8 turn and the signal light comes on as does the clip
light (solid). No noise from ch2 output.
Seems as though I may have offended the electronic sensibility of ch2.
I have pushed the 2450 to shut down once before in 2 years. It
recovered nicely after the first time and it was pushed much harder
that time. I would not have expected it to crap out on this occasion,
but alas, I was wrong.
So, any quick checks for a moderately untaleneted electrical engineer
to conduct or should I leave it to the local dealer for service?
Many thanks for the help,
Tom
BTW, I am buying a Behringer EP2500 so I can run one 1208 on each big
amp (after I get this 2450 fixed). I get to open them both up and see
how the guts compare.

Ok, I just got around to opening the 2450 and there was a blown 250v 20A
fuze on ch2. I replaced it and the amp appears to be up and running.

Does

Post by Tom Hole
this sound reasonable? If so, I consider myself a lucky man.
Tom

Check to make sure it's not running hot. Older ones would have failures of
the commutator devices that switch rails, they would stick at high voltage
and cause increased heat/current consumption. Also check for intermittent
(broken) leads in the driver transistors. These can become intermittent and
cause the fuse to blow.

If the unit is older there are a bunch of tech bulletins out there. QSC may
give them to you, they may be on their site, or your local service center
will certainly have them.

Chad

[Pooh Bear]

Post by Tom Hole
Before I run this off to the dealer, I wanted to check with the
experts here.
I have a QSC RMX 2450 that I run in bridge mono to 2 Yorkville LS1208
subs (1200 watts, 8 ohms each). At the end of the gig 2 weeks ago, I
was running them hard with moderate clipping on the 2450. The 2450
shut down, so I switched to my backup amp and figured the 2450 would
come out of whatever protect it went into and all would be good. I
checked the 2450 and it is not behaving. It powers up and all looks
well. I apply a signal and turn up ch 1 and the ch1 signal light
comes on as expected. The ch2 signal light comes on, too, but so does
the ch2 clip light and this is with the ch2 input turned down as it
should be. So, I switch to stereo, unbridged and apply a signal to
ch1. All is well on ch1. Apply the signal to ch2 and turn up the
input about 1/8 turn and the signal light comes on as does the clip
light (solid). No noise from ch2 output.

Figures.

The clip led is 'triggered' by an internal overvoltage condition inside
the amplifier which indicates non-linear operation.

Ch 2 is getting a signal in bridged mode but is faulty - hence the clip
led.

Post by Tom Hole
Seems as though I may have offended the electronic sensibility of ch2.

Looks like it.

Post by Tom Hole
I have pushed the 2450 to shut down once before in 2 years. It
recovered nicely after the first time and it was pushed much harder
that time. I would not have expected it to crap out on this occasion,
but alas, I was wrong.
So, any quick checks for a moderately untaleneted electrical engineer
to conduct or should I leave it to the local dealer for service?

Unless you're familiar with the beast I wouldn't recommend it.


Graham