Question regarding where the crossover fits in the PA chain

[unknown]

(Appologies for the rambling nature of the message...)

I have a query regarding where an active crossover fits in the sound
system chain. And, please be aware that I know that the stuff that I
have is VERY old technology.

An overview of my system is a 16-channel mixer (Peavey) with the mains
going through a Fender 600 watt power amp and the monitor mix going
through a 200 watt no-name (although it was purported to be a Traynor)
power amp. The mains go out to a couple of Community 2-way cabinets
and the monitors go out to a series of monitors that are so old that
the name plates have long since disappeared. The mixer is looped with
a digital delay and an outboard EQ...one side of the EQ does the
mains, the other side does the monitors.

I now want to add an active crossover device to this configuration so
that I may add a low frequency cabinet. I have a DOD R-835 crossover
that I purchased used off of ebay and, of course, there is no manual
although I did manage to find some documentation online. Again, please
remember that all of this stuff is being put together more as a
learning experience although it may be used to play weddings, dances,
etc at very moderate volumes.

My biggest problem is that I am getting mixed signals from the various
articles and tutorials that I have been reading. Some state that the
crossover goes between the mixer and the power amp(s), while others
state that the crossover is the last item in the chain before the
signal goes out to the cabinets. Could someone please set me on the
right path here as I really would like to get this setup working so
that I can play with the PA a bit.

Thanks in advance...

Doug

[Gareth Magennis]

Post by unknown
I now want to add an active crossover device to this configuration so
that I may add a low frequency cabinet. I have a DOD R-835 crossover
that I purchased used off of ebay and, of course, there is no manual
although I did manage to find some documentation online. Again, please
remember that all of this stuff is being put together more as a
learning experience although it may be used to play weddings, dances,
etc at very moderate volumes.
My biggest problem is that I am getting mixed signals from the various
articles and tutorials that I have been reading. Some state that the
crossover goes between the mixer and the power amp(s), while others
state that the crossover is the last item in the chain before the
signal goes out to the cabinets. Could someone please set me on the
right path here as I really would like to get this setup working so
that I can play with the PA a bit.

You are getting confused between active crossovers and passive crossovers.
Passive crossovers are big things that sit inside speaker cabinets and
divert the power from the power amps to the desired speakers - bass to bass
speaker and top to tops etc. Active crossovers, your DOD for example, work
on signals from the desk etc. This splits the signal into bass, mid and
top, for example, and these signals then go to power amplifiers to be
ampified and drive the corresponding speaker boxes. So the Dod will sit
between the desk and the power amplifiers.
The downside of using an active crossover is you need more amplifiers. A
three-way stereo crossover will have 6 outputs (Bass, Mid, Top for left and
right) and so will require 3 stereo power amplifiers to drive six cabinets
(2 bass bins, 2 mid bins, 2 top boxes). A passive system can be driven from
a single (large)stereo power amplifier because the active crossovers are
working on the amplifier outputs.

Gareth.

[Gareth Magennis]

. A passive system can be driven from

Post by Gareth Magennis
a single (large)stereo power amplifier because the active crossovers are
working on the amplifier outputs.

Dammit, I meant the PASSIVE crossovers are working on the amplifier outputs.

[Andy Hart]

In message <***@4ax.com>,
w989531@?.?.invalid writes

[snip]

Post by unknown
My biggest problem is that I am getting mixed signals from the various
articles and tutorials that I have been reading. Some state that the
crossover goes between the mixer and the power amp(s),

Correct :-)

Post by unknown
while others
state that the crossover is the last item in the chain before the
signal goes out to the cabinets.

Wrong :-( ... If this were the case the crossover would be accepting
speaker voltage and that would probably destroy it.

Post by unknown
Could someone please set me on the
right path here as I really would like to get this setup working so
that I can play with the PA a bit.

The last items in the chain should be ...

Crossover ... Power amps ... Speakers

Output from Desk
|
|
Crossover
High / \ Low
/ \
/ \
/ \
Amp(1) Amp(2)
| |
| |
| |
Top Cabs Bass Cabs

The above depicts a MONO system, for Stereo everything gets doubled

[Mike]

Post by Andy Hart
[snip]

Post by unknown
My biggest problem is that I am getting mixed signals from
the various articles and tutorials that I have been reading.
Some state that the crossover goes between the mixer
and the power amp(s),

Correct :-)

Assuming an active crossover....

Post by Andy Hart

Post by unknown
while others state that the crossover is the last item in the
chain before the signal goes out to the cabinets.

Wrong :-( ... If this were the case the crossover would be
accepting speaker voltage and that would probably destroy it.

Unless it's a passive crossover designed for speaker levels. =)

Mike Borkhuis

[Andy Hart]

Post by Mike

Post by Andy Hart
[snip]

Post by unknown
My biggest problem is that I am getting mixed signals from
the various articles and tutorials that I have been reading.
Some state that the crossover goes between the mixer
and the power amp(s),

Correct :-)

Assuming an active crossover....

Correct :-)

Post by Mike

Post by Andy Hart

Post by unknown
while others state that the crossover is the last item in the
chain before the signal goes out to the cabinets.

Wrong :-( ... If this were the case the crossover would be
accepting speaker voltage and that would probably destroy it.

Unless it's a passive crossover designed for speaker levels. =)

Yes, I was assuming an active crossover as the OP said ...

"I have a DOD R-835 crossover"

But you are correct in saying that a *PASSIVE* crossover goes between
the output of the power amp and the speakers.

[Mike]

Post by unknown
An overview of my system is a 16-channel mixer (Peavey) with
the mains going through a Fender 600 watt power amp and the
monitor mix going through a 200 watt no-name (although it was
purported to be a Traynor) power amp. The mains go out to a
couple of Community 2-way cabinets and the monitors go out
to a series of monitors that are so old that the name plates have
long since disappeared. The mixer is looped with a digital delay
and an outboard EQ...one side of the EQ does the mains, the
other side does the monitors.
I now want to add an active crossover device to this configuration
so that I may add a low frequency cabinet. I have a DOD R-835
crossover that I purchased used off of ebay and, of course, there
is no manual although I did manage to find some documentation
online. Again, please remember that all of this stuff is being put
together more as a learning experience although it may be used
to play weddings, dances, etc at very moderate volumes.
My biggest problem is that I am getting mixed signals from the
various articles and tutorials that I have been reading. Some state
that the crossover goes between the mixer and the power amp(s),
while others state that the crossover is the last item in the chain
before the signal goes out to the cabinets. Could someone please
set me on the right path here as I really would like to get this setup
working so that I can play with the PA a bit.

OK, here's the typical setup......

Mixer --> EQ --> Active Crossover
The HIGH output of the crossover feeds you main amp...
The LOW output of the crossover feeds the sub amps....

Mike Borkhuis

[unknown]

Thanks to all that have been so kind to offer suggestions for my
crossover plight. It appears as though my Fender M-500 power amp may
be the crux of the rpoblem.

The M-500 is used to power the mains while a much lesser power amp is
used to power the low end. An aditional power amp is used to power the
monitors. Using this setup, all I can get is sound out of the low end.
So, through the rpocess of elimination, I disconnected the M-500 from
the high output of the crossover and connected the output to the
monitor power amp which now has the mains plugged in to it. BINGO,
everything works through the crossover as it is supposed to. BUT...as
soon as I cable it up the same way using the M-500...no mains.

Again...thanks to you folks for setting me in the proper direction in
the first place. You instructions allowed me to safely get as far as I
have. And...I now have a VERY bargain basement PA setup that has the
capabilities of routing the mids and highs to the regular cabinets and
the lows to the bass cabinet. Woohoo...it may not seem like much to
you, but it is ecstasy to me.

I'm sure that I will be back with more questions. Thanks again...