Biamping JBL VRX932LA-1

[nandan21]

If I biamp JBL VRX, what are the advantages that i will get? Apart
from getting rid of power sucking 'passive Xover' of the Box (I have
read somewhere that they sap-up 30% of power into heat). What kind of
addition control and extra loudness I will be getting?

[liquidator]

Post by nandan21
If I biamp JBL VRX, what are the advantages that i will get? Apart
from getting rid of power sucking 'passive Xover' of the Box (I have
read somewhere that they sap-up 30% of power into heat). What kind of
addition control and extra loudness I will be getting?

Gonna attemt a 101 level explanation.

Yes, some power is lost in the crossover. Even at 30% though it would take
very trained ears to tell the difference- so that is not a biggie.

Passive crossovers have phase shift issues, nad many are just "textbook"
designs not optimized for the drivers involved. These issues are liminated
with active.

Think about what happens when loud bass occurs- all the power is pulled
from the amp's supply by the bass. This is very oversimplified, Graham or
Phil would be the "go to" guys for a better explanation. But with seperate
amps, if the bass amp gets driven to the max, the highs stay cleaner.

So the major beneft is cleaner sound and gettting rid of the phase shift
issues. Depending on how bad the passives were, the difference can be
amazing.

With a unit like the Behringer 2496 or Driverack, you also get time align
functions- if you have folded horn bass for instance the sound is "out of
step" with the mid and tops, due to the length of time it takes the sound to
go around all those folds. Time align will delay the mid top so all
freqencies arrive in unison- again a clarity improvement.

Plus EQ and other functions, but we are drifting away from what you asked.

HTH. It is very ovesimplified. Maybe somebody else here can explain better.

[Rupert]

Post by liquidator

Post by nandan21
If I biamp JBL VRX, what are the advantages that i will get? Apart
from getting rid of power sucking 'passive Xover' of the Box (I have
read somewhere that they sap-up 30% of power into heat). What kind of
addition control and extra loudness I will be getting?

Gonna attemt a 101 level explanation.
Yes, some power is lost in the crossover. Even at 30% though it would take
very trained ears to tell the difference- so that is not a biggie.
 Passive crossovers have phase shift issues, nad many are just "textbook"
designs not optimized for the drivers involved. These issues are liminated
with active.
 Think about what happens when loud bass occurs- all the power is pulled
from the amp's supply by the bass. This is very oversimplified, Graham or
Phil would be the "go to" guys for a better explanation. But with seperate
amps, if the bass amp gets driven to the max, the highs stay cleaner.
So the major beneft is cleaner sound and gettting rid of the phase shift
issues. Depending on how bad the passives were, the difference can be
amazing.
With a unit like the Behringer 2496 or Driverack, you also get time align
functions- if you have folded horn bass for instance the sound is "out of
step" with the mid and tops, due to the length of time it takes the sound to
go around all those folds. Time align will delay the mid top so all
freqencies arrive in unison- again a clarity improvement.
Plus EQ and other functions, but we are drifting away from what you asked.
HTH. It is very ovesimplified. Maybe somebody else here can explain better.

I'll add that often crossover slopes used in passive designs aren't as
steep as the industry standard 24dB per octave (4th order) filters
used in most modern active crossovers and speaker processors. The
steep slope can increase power handling and output of the mid and/or
high frequency driver(s) since the low frequency roll-off is faster
for those drivers. The lower frequency mid and high frequency drivers
have to produce, the less power they can handle. Having the steeper
slope also allows for less overlap of the band passes and therefore
reduces the negative interactions between them. The slower the roll-
off, the more the band-passes reproduce the same signal, the more
likely you'll get some combing of those frequencies due to different
time arrivals of those frequencies from separate sources (not to
mention the driver models and loadings are different). Many of the
newer speaker processors have 48dB per octave filters, but those
filters have a tendency to "ring" noticeably compared to the 24db/oct.
filters.

Rupert

[liquidator]

Post by liquidator

Post by nandan21
If I biamp JBL VRX, what are the advantages that i will get? Apart
from getting rid of power sucking 'passive Xover' of the Box (I have
read somewhere that they sap-up 30% of power into heat). What kind of
addition control and extra loudness I will be getting?

Gonna attemt a 101 level explanation.
Yes, some power is lost in the crossover. Even at 30% though it would take
very trained ears to tell the difference- so that is not a biggie.
Passive crossovers have phase shift issues, nad many are just "textbook"
designs not optimized for the drivers involved. These issues are liminated
with active.
Think about what happens when loud bass occurs- all the power is pulled
from the amp's supply by the bass. This is very oversimplified, Graham or
Phil would be the "go to" guys for a better explanation. But with seperate
amps, if the bass amp gets driven to the max, the highs stay cleaner.
So the major beneft is cleaner sound and gettting rid of the phase shift
issues. Depending on how bad the passives were, the difference can be
amazing.
With a unit like the Behringer 2496 or Driverack, you also get time align
functions- if you have folded horn bass for instance the sound is "out of
step" with the mid and tops, due to the length of time it takes the sound to
go around all those folds. Time align will delay the mid top so all
freqencies arrive in unison- again a clarity improvement.
Plus EQ and other functions, but we are drifting away from what you asked.
HTH. It is very ovesimplified. Maybe somebody else here can explain better.

I'll add that often crossover slopes used in passive designs aren't as
steep as the industry standard 24dB per octave (4th order) filters
used in most modern active crossovers and speaker processors. The
steep slope can increase power handling and output of the mid and/or
high frequency driver(s) since the low frequency roll-off is faster
for those drivers. The lower frequency mid and high frequency drivers
have to produce, the less power they can handle. Having the steeper
slope also allows for less overlap of the band passes and therefore
reduces the negative interactions between them. The slower the roll-
off, the more the band-passes reproduce the same signal, the more
likely you'll get some combing of those frequencies due to different
time arrivals of those frequencies from separate sources (not to
mention the driver models and loadings are different). Many of the
newer speaker processors have 48dB per octave filters, but those
filters have a tendency to "ring" noticeably compared to the 24db/oct.
filters.

Thanks- I feel kinda dumb leaving that out, what happens when you try to
oversimplify.

[Eeyore]

Post by Rupert

Post by liquidator
HTH. It is very ovesimplified. Maybe somebody else here can explain better.

I'll add that often crossover slopes used in passive designs aren't as
steep as the industry standard 24dB per octave (4th order) filters
used in most modern active crossovers and speaker processors.

And you even choose the filter order and Butterworth or Linkwitz-Riley crossover
characteristics. Certrainly in the Driverack PA for example, having just set one
up.

Post by Rupert
The steep slope can increase power handling and output of the mid and/or
high frequency driver(s) since the low frequency roll-off is faster
for those drivers. The lower frequency mid and high frequency drivers
have to produce, the less power they can handle. Having the steeper
slope also allows for less overlap of the band passes and therefore
reduces the negative interactions between them. The slower the roll-
off, the more the band-passes reproduce the same signal, the more
likely you'll get some combing of those frequencies due to different
time arrivals of those frequencies from separate sources (not to
mention the driver models and loadings are different). Many of the
newer speaker processors have 48dB per octave filters, but those
filters have a tendency to "ring" noticeably compared to the 24db/oct.
filters.

Note also that active crossovers and certainly controllers also typically have a
very low frequency high pass filter. It's set at 35Hz with the EV QRx 218s we have
for instance @ 24dB/octave. This stops power being wasted trying to reproduce
frequencies the speaker can't handle, thus giving you more overall headroom. It
also helps protect the speaker from abuse.

Graham

[nandan21]

Post by Eeyore

Post by Rupert

Post by liquidator
HTH. It is very ovesimplified. Maybe somebody else here can explain better.

I'll add that often crossover slopes used in passive designs aren't as
steep as the industry standard 24dB per octave (4th order) filters
used in most modern active crossovers and speaker processors.

And you even choose the filter order and Butterworth or Linkwitz-Riley crossover
characteristics. Certrainly in the Driverack PA for example, having just set one
up.

Post by Rupert
The steep slope can increase power handling and output of the mid and/or
high frequency driver(s) since the low frequency roll-off is faster
for those drivers. The lower frequency mid and high frequency drivers
have to produce, the less power they can handle. Having the steeper
slope also allows for less overlap of the band passes and therefore
reduces the negative interactions between them. The slower the roll-
off, the more the band-passes reproduce the same signal, the more
likely you'll get some combing of those frequencies due to different
time arrivals of those frequencies from separate sources (not to
mention the driver models and loadings are different). Many of the
newer speaker processors have 48dB per octave filters, but those
filters have a tendency to "ring" noticeably compared to the 24db/oct.
filters.

Note also that active crossovers and certainly controllers also typically have a
very low frequency high pass filter. It's set at 35Hz with the EV QRx 218s we have
frequencies the speaker can't handle, thus giving you more overall headroom. It
also helps protect the speaker from abuse.
Graham

I have been using DR PA since.........ages so using infasonic filers
(read very low frequencies) is not an issue also I'm aware of speaker
'unloading' . My concern is Hi frequency and mid coupling, power
requirement, and time alignment issues., I am very scared to drive HF
on a separate amp.

[Tim Perry]

Post by nandan21
I have been using DR PA since.........ages so using infasonic filers

(read very low frequencies) is not an issue also I'm aware of speaker
'unloading' . My concern is Hi frequency and mid coupling, power
requirement, and time alignment issues., I am very scared to drive HF
on a separate amp.


kind of an interesting speaker. Cost over $2k each.
http://www.jblpro.com/products/portablesound/vrx/PDFs/VRX932LA-1_FINAL.PDF


for what is worth you might want to check this out
http://www2.jblpro.com/catalog/support/getfile.aspx?doctype=3&docid=1074
at least it has pretty colored pictures

At the JBLPRO site you can download the "tunings". The data covers various
types of processors including a DRPA.

[Eeyore]

I am very scared to drive HF on a separate amp.

Why ? It's the best thing ever. I was doing it around 35 years ago. And my rig got
consistent positive comments for sound quality and we never burnt out a single 1823M or
Vitavox S2A.

Graham

[Eeyore]

Post by nandan21
If I biamp JBL VRX, what are the advantages that i will get? Apart
from getting rid of power sucking 'passive Xover' of the Box (I have
read somewhere that they sap-up 30% of power into heat). What kind of
addition control and extra loudness I will be getting?

One of the best advantages is that you can match the amp power to each
section. This may allow the use of more watts overall as well as
eliminating as the crossover losses.

Also LF clipping won't reach the HF drivers, so the sound may be cleaner.

Oh, and without a passive crossover, the damping factor will improve a
bit too.

Graham

[Phil Allison]

"nandan21"

Post by nandan21
If I biamp JBL VRX, what are the advantages that i will get?

** The main one is the treble horns will never be overdriven - long as you
pick the right amplifier.

Post by nandan21
Apart
from getting rid of power sucking 'passive Xover' of the Box (I have
read somewhere that they sap-up 30% of power into heat).

** Back of a dunny door - was it ??

Post by nandan21
What kind of
addition control and extra loudness I will be getting?

** You can adjust bass and treble drive levels, x-over frequency, slopes,
peak limiting and EQ all from a panel at the effect's rack.



..... Phil

[Phil Allison]

"nandan21"

Post by nandan21
If I biamp JBL VRX, what are the advantages that i will get?

** You need to ask another question:

" What are the risks, hazards and drawbacks of me going " active
-amp" - considering that the whole system will be portable and set up and
operation will be in the hands of a congenital dimwit ? "





..... Phil