QSC MX 1500 NOT 1500a

[g***@gmail.com]

I have a couple of QSC MX 1500 amps. These seem to be different than the MX
1500a (most likely older). What I'm trying to find out is this. In bridge
mono mode the 1500s I have say on the back they will run at 4 ohms. The
1500a says minimum 8 ohms. Does anybody know what the volume knob settings
on the 1500 should be when set to run bridge mono? I have been unable to
locate a manual for these amps. The MX 1500a looks enough different that I
don't want to assume they are set up the same way.
Thanks

tech sheet is here http://audio.manualsonline.com/manuals/mfg/qsc_audio/mx_1500.html?p=2
2x750W @ 2 Ohm channel / 1500W bridge @ 4ohm

[Peter Larsen]

Post by g***@gmail.com

I have a couple of QSC MX 1500 amps. These seem to be different than the MX
1500a (most likely older). What I'm trying to find out is this. In bridge
mono mode the 1500s I have say on the back they will run at 4 ohms. The
1500a says minimum 8 ohms. Does anybody know what the volume knob settings
on the 1500 should be when set to run bridge mono? I have been unable to
locate a manual for these amps. The MX 1500a looks enough different that I
don't want to assume they are set up the same way.
Thanks

Usually a bridged amp uses the left channel input and it should have the
left channel flat out and the right channel input turned down if there
are input level controls. Output "hot" is left channel "hot" and output
"return" is right channel "hot". That is how it "usually is".

What you want to know is minimum allowed load in stereo mode, double
that for bridge mode.

QSC is still around ... http://www.qsc.com/

Kind regards

Peter Larsen

Post by g***@gmail.com
tech sheet is here http://audio.manualsonline.com/manuals/mfg/qsc_audio/mx_1500.html?p=2

[Phil Allison]

Post by Peter Larsen
Usually a bridged amp uses the left channel input and it should have the
left channel flat out and the right channel input turned down if there
are input level controls. Output "hot" is left channel "hot" and output
"return" is right channel "hot". That is how it "usually is".

** Then there are the exceptions where both input level controls have to be turned up full.

The trap being that if one is turned down, the amp still works but the quiet channel overheats something fearful as it acts as a virtual ground for the speaker.

Lotsa current with no voltage swing, very similar to having that channel's output shorted.



.... Phil

[Peter Larsen]

Post by Phil Allison

Post by Peter Larsen
Usually a bridged amp uses the left channel input and it should have the
left channel flat out and the right channel input turned down if there
are input level controls. Output "hot" is left channel "hot" and output
"return" is right channel "hot". That is how it "usually is".

** Then there are the exceptions where both input level controls have to be turned up full.
The trap being that if one is turned down, the amp still works but the quiet channel overheats something fearful as it acts as a virtual ground for the speaker.
Lotsa current with no voltage swing, very similar to having that channel's output shorted.

Thank you!

Post by Phil Allison
.... Phil

Kind regards

Peter Larsen

[p***@hotmail.com]

Post by Phil Allison

Post by Peter Larsen
Usually a bridged amp uses the left channel input and it should have the
left channel flat out and the right channel input turned down if there
are input level controls. Output "hot" is left channel "hot" and output
"return" is right channel "hot". That is how it "usually is".

** Then there are the exceptions where both input level controls have to be turned up full.
The trap being that if one is turned down, the amp still works but the quiet channel overheats something fearful as it acts as a virtual ground for the speaker.
Lotsa current with no voltage swing, very similar to having that channel's output shorted.
.... Phil

Christ ! You're correct for once but it only applies to shitty amplifiers. In decent designs, the Ch1 gain control / attenuator is all that matters. Ch2 can be anywhere. RTFM !

Graham

[Phil Allison]

Post by p***@hotmail.com

Post by Phil Allison
** Then there are the exceptions where both input level controls have to be turned up full.
The trap being that if one is turned down, the amp still works but the quiet channel overheats something fearful as it acts as a virtual ground for the speaker.
Lotsa current with no voltage swing, very similar to having that channel's output shorted.

Christ ! You're correct for once but it only applies to shitty amplifiers.

** Shame those "shitty amplifiers" are made by QSC or are clones of same.

Not that you would have one tiny a clue abut that.

Post by p***@hotmail.com
In decent designs,

** Yawwnnnnnnnnnnnnnnnnnnnn.............

Post by p***@hotmail.com
Graham

** Tell us, did you escape or were you let out ?

I either case, better keep up the meds.



... love, Phil

[Tropical Innovation]

Post by p***@hotmail.com

Post by Phil Allison
** Then there are the exceptions where both input level controls have to be turned up full.
The trap being that if one is turned down, the amp still works but the quiet channel overheats something fearful as it acts as a virtual ground for the speaker.
Lotsa current with no voltage swing, very similar to having that channel's output shorted.

Christ ! You're correct for once but it only applies to shitty amplifiers.

** Shame those "shitty amplifiers" are made by QSC or are clones of same.
Not that you would have one tiny a clue abut that.

Post by p***@hotmail.com
In decent designs,

** Yawwnnnnnnnnnnnnnnnnnnnn.............

Post by p***@hotmail.com
Graham

** Tell us, did you escape or were you let out ?
I either case, better keep up the meds.
... love, Phil

*** I tested the amp on bridged and used the left channel. my volt meter set to AC 150V for testing. shows 60V, I wondered because this is the same voltage of the channel when in stereo mode so I turned up the right volume and there was signal even though the left channel alone was connected at the back. to voltage started raising to over 120 Volts. the manual also says that the amp can output voltages up to 120V when bridged. So both channels should be turned right up in bridge mode.

[a***@gmail.com]

It should always be in full.

[a***@gmail.com]

I have a couple of QSC MX 1500 amps. These seem to be different than the MX
1500a (most likely older). What I'm trying to find out is this. In bridge
mono mode the 1500s I have say on the back they will run at 4 ohms. The
1500a says minimum 8 ohms. Does anybody know what the volume knob settings
on the 1500 should be when set to run bridge mono? I have been unable to
locate a manual for these amps. The MX 1500a looks enough different that I
don't want to assume they are set up the same way.
Thanks

https://www.qsc.com/resource-files/productresources/amp/discontinued/mx/mx_1500/q_amp_mx_mx1500_specs.pdf