Speaker set up. Am i doing the right thing

[bluishbob]

Hey all, i have a bit of a story but i want to check that i am doing the right thing to get the most out of the system that i have to play with.

ok, i have a disco that i am doing at my school next week. The school have a a new peavey pa system.

So i went today into the hall to see whether i could link my own amp to the internal crossover of the peavey amp (run them in a series) so that my speakers i could use as just bass and i could use the peaveys as mid/top.

The system is two peavey impulse speakers (500watt RMS @8ohms with A program power of 1k) and a peavey 1500 amp (300 watts @8ohms )
:confused: :confused: :confused:

Now the technician (who ordered all the equipment last year) seemed to think that there was nothing wrong when i tried to explain to him that the speakers were drasticly under powered this afternoon and didn't believe me that the amp is in danger of blowing because its under too much pressure (which is what several people have told me). It seemed that i was 'just a student' and he knew better:bang: :bang: .


SO..... my plan is to run the peavey bridged, and run the speakers in parallel. Peavey spec says that that amp will run 1500 watts in 4ohms bridged. Than i will take a 'low output through' tp parallel into my own amp, which i will put one speaker in each corner and use tham for bass.

I know that this is bodging, but it seems to me that its the best option, as i will be getting closer to the power that they can produce (although i do end up loosing stereo), What do you lot think???

[TonyB]

I would say I agree with the technician. Amplifiers drive speakers and it doesn't matter if they are 200w or 1000w speakers attached to the amp, it will still only output what it is capable of i.e. 300w at 8 ohms. Bridging the amp is more likely to more more strain on it and cause problems.

If my understanding is correct, you are going to use the school system for the tops and your own for the bass. Tops will require a lot less power than the bass bins so 300w a channel would probably be enough but it depends on the size of the venue, venue acoustics and number of people.

What power is your own system that you are going to use for the bass and do you have proper bass bins or are you going to use full range cabs for the bass?

[colint]

1500 watts into 1000 watts of speakers Mmmm! sounds interesting?

taking into account that a speaker load goes up and down during use do you really think this is a good idea?
Under load your 4 ohms can drop as low as 2 ohms and I think concidering this is not your kit you really shouldn't mess with it or you could end up with a hefty repair bill!

if your going to connect you own gear to the school system just take the signal you need and leave there own speakers as they are! and remember red lights mean STOP!

[super-hero]

Probably easir to just use your own system and not bother using the schools. If there are any problems with their kit afterwards they will blame you.

Just out of interest, how many people is the disco for?

[bluishbob]

Sorry to quote but when i brought this subject up a few weeks ago the general consensus was this, Quoting 'Spin Mobile Disco'


I asked peavey this question [what is the best amplifier wattage] and also mackie and they both said double the rms value and dont allow clipping for the maximum output. I use a 500 watt rms per side amp to power a 300 watt rms speaker each side. This gives me significant headroom and has been good for me.

Now sorry, and correct me if i am wrong (i may well be) but by my logic if an amp is delivering 1500watts at 4ohms, running speakers of 1000 watts rms at 4ohms (2 500watt 8ohm cabs in parallel) Then there is nop reason why that amp should be under any great amount of pressure. The issue is that (so i have been told by several reputable sound engineers) you can do more damage under powering a speaker than over powering it. (over powering gives a warning (distortion) whereas underpowering can just blow without warning)

As for my own system, i have 2 300watt full range speakers that i will 'use as bass cabs', and as much as it may be seen as a bodge and it isn't ideal, due to the fact that it will be run through a crossover, i don't see how there can be a problem there. (the person who had them before me used them like this for sdeveral years)

There is usually around 250 kids, and i will usually run the two systems together as they are . But i just wanted to boost the power so i wasn't sat with my faders all up by the end of the night and having to watch the amps/mixer like a hawk for clipping.

thing is that i am the current 'techie' in school and if the kit is ever used, its usually by me for one of the productions or something. (Its not asthough i have just randomly walked into a school that has hired me for one night.

[colint]

Sorry to quote but when i brought this subject up a few weeks ago the general consensus was this, Quoting 'Spin Mobile Disco'



Now sorry, and correct me if i am wrong (i may well be) but by my logic if an amp is delivering 1500watts at 4ohms, running speakers of 1000 watts rms at 4ohms (2 500watt 8ohm cabs in parallel) Then there is nop reason why that amp should be under any great amount of pressure. The issue is that (so i have been told by several reputable sound engineers) you can do more damage under powering a speaker than over powering it. (over powering gives a warning (distortion) whereas underpowering can just blow without warning)

As for my own system, i have 2 300watt full range speakers that i will 'use as bass cabs', and as much as it may be seen as a bodge and it isn't ideal, due to the fact that it will be run through a crossover, i don't see how there can be a problem there. (the person who had them before me used them like this for sdeveral years)

There is usually around 250 kids, and i will usually run the two systems together as they are . But i just wanted to boost the power so i wasn't sat with my faders all up by the end of the night and having to watch the amps/mixer like a hawk for clipping.

thing is that i am the current 'techie' in school and if the kit is ever used, its usually by me for one of the productions or something. (Its not asthough i have just randomly walked into a school that has hired me for one night.

Although you have most of this right (The under powered amp thing & by the way any amp will distort if overdrivern) unless you have the proper bass cabs I don't see what your going to gain by running full range cabs through a crossover, if fact I would think it would be louder if you dropped the crossover out and ran your speakers at full range!

just out of interest if the school has no bass speakers why do they have a crossover on the system in the first place?

[super-hero]

Does your mixer have a seporate output to run a sub amp from? or does it have a "booth out" or "record out", if so you could connect the school p.a to your main output, and your amp and speakers to one of the other outputs.

Then you could adjust the volume of their speakers and yours seporatly.

[Excalibur]

Although you have most of this right (The under powered amp thing & by the way any amp will distort if overdrivern) unless you have the proper bass cabs I don't see what your going to gain by running full range cabs through a crossover, if fact I would think it would be louder if you dropped the crossover out and ran your speakers at full range!

just out of interest if the school has no bass speakers why do they have a crossover on the system in the first place?

I think he's refering to the fact that some Peavey (and other ) amps have an internal crossover, delivering low frequency outputs to another ( bass) amp.

[bluishbob]

I think he's refering to the fact that some Peavey (and other ) amps have an internal crossover, delivering low frequency outputs to another ( bass) amp.

Thats right!!!

to be honest, im not that bothered about my own system, i do have a booth output and usually i do run one amp on master and one on booth. The bass output from the amp was just a secondary thought.

My real concern is the peavey setup.

Surely (forget the fact that it will be run in mono and not stereo) it would be better to run the amp bridged in 4ohms to the speakers in parallel. So 1000 watts (4ohms) of speakers power is run by 1500watts (4ohms) amp power. Rather that having 500watts (8ohms) x2 of speaker power run by 300watts (8ohms) x2 of amp power.

[Excalibur]

Hey all, i have a bit of a story but i want to check that i am doing the right thing to get the most out of the system that i have to play with.

ok, i have a disco that i am doing at my school next week. The school have a a new peavey pa system.

So i went today into the hall to see whether i could link my own amp to the internal crossover of the peavey amp (run them in a series) so that my speakers i could use as just bass and i could use the peaveys as mid/top.

The system is two peavey impulse speakers (500watt RMS @8ohms with A program power of 1k) and a peavey 1500 amp (300 watts @8ohms )
:confused: :confused: :confused:

Now the technician (who ordered all the equipment last year) seemed to think that there was nothing wrong when i tried to explain to him that the speakers were drasticly under powered this afternoon and didn't believe me that the amp is in danger of blowing because its under too much pressure (which is what several people have told me). It seemed that i was 'just a student' and he knew better:bang: :bang: .


SO..... my plan is to run the peavey bridged, and run the speakers in parallel. Peavey spec says that that amp will run 1500 watts in 4ohms bridged. Than i will take a 'low output through' tp parallel into my own amp, which i will put one speaker in each corner and use tham for bass.

I know that this is bodging, but it seems to me that its the best option, as i will be getting closer to the power that they can produce (although i do end up loosing stereo), What do you lot think???

We've had this before, BTW. Running an amp at 4ohms bridged is equivalent to running it at 2ohms stereo. Peavey say this is fine, but it is running the amp very hard, and IMHO inadvisable. The best advice I have seen is to run two separate outs from your mixer, and run both systems full range, stereo.

[colint]

I think he's refering to the fact that some Peavey (and other ) amps have an internal crossover, delivering low frequency outputs to another ( bass) amp.

In which case it wouldn't work any way, if it's the PV1500 amp I think you'll find it's only internal! (but I could be wrong) I had one of these amps for a while but never used the filter,
The only way this will work is with the proper bass cabs added to the system and then only with the proper crossover or passive crossed over cabs.

Have you thought about hiring a pair of bass cabs & amp?

The other thing I thought of ? are you sure the speakers are 8ohms because the impulse are also avalable in 4ohm format too!

[Excalibur]

In which case it wouldn't work any way, if it's the PV1500 amp I think you'll find it's only internal! (but I could be wrong) I had one of these amps for a while but never used the filter,
The only way this will work is with the proper bass cabs added to the system and then only with the proper crossover or passive crossed over cabs.

Have you thought about hiring a pair of bass cabs & amp?

I'm not saying you're wrong, but I think you're wrong!:p
I saw a band recently using this setup with a Peavey amp running full range cabs, and the sub output from this amp fed one running the subs. A very neat and simple setup, no external crosover, no passive in bass cabs, I liked it. From the ( very fuzzy) pictures on Peavey's site, this amp appears to have that facility.

[colint]

I just checked and the amp does have a thro out for both the bass & high filters but it will also put the amp into either mode! so what ever mode you select the amp will deliver the same!

[Excalibur]

In which case it wouldn't work any way, if it's the PV1500 amp I think you'll find it's only internal! (but I could be wrong) I had one of these amps for a while but never used the filter,
The only way this will work is with the proper bass cabs added to the system and then only with the proper crossover or passive crossed over cabs.

Have you thought about hiring a pair of bass cabs & amp?

The other thing I thought of ? are you sure the speakers are 8ohms because the impulse are also avalable in 4ohm format too!

On Peavey's site Impulse are only 8 ohms, but I found one with impulse subs at 4ohms. I have to admit this was my first thought also.

[colint]

This is taken from the PV1500 manual!

CROSSOVER SWITCH (150 Hz XOVER
This switch is used to activate the 150 Hz crossover for the corresponding channel. It is also a pushpush
type switch and requires a small “tool” to activate. The PV® offers two 150 Hz crossovers. These
are specially designed features that enhance the response of most loudspeakers in a typical bi-amped
application. Rather than just having a flat output curve, these crossovers use special filters to tailor the
response and provide a flat acoustical output. This type of crossover “sounds” more natural than
conventional “state-variable” type crossovers.
With the switch IN, the input signals are routed through the crossover, and the low frequencies are
automatically sent to the corresponding channel. At the same time, the high frequencies are sent
to the HIGH OUT (18) jack and must then be patched to INPUT of the other channel of this amplifier
or to another amplifier input to complete the bi-amped system. Additionally, the low frequencies are
sent to the THRU/LOW OUT (17) jack, and can be patched to other amplifier inputs to permit even
larger systems. With the switch OUT the crossover is defeated, and the input signal is routed directly
to the respective power amp channel. The crossover frequency is fixed at 150 Hz and cannot be
changed. The crossover configuration is a 4-pole Linkwitz-Riley approximation.
(17) THRU/LOW OUT JACKS
As per previous crossover discussion, this 1/4" jack supplies low-frequency out signals from the
activated crossover for patching to additional power amplifier inputs, providing added flexibility in
larger bi-amped systems. When the crossover function is not activated, this jack converts to a THRU
function, where the output of the electronically balanced input circuitry is supplied to this jack. The
THRU function provides the means to patch a full range input signal to the other input of this
amplifier (parallel mode), or to other amp inputs in the same rack. This function allows one balanced
mixer feed to be connected to the amp via the desired balanced input connector (XLR, 1/4", Barrier),
and then further distributed locally. Regardless of the crossover switch position, this 1/4" jack provides
an unbalanced (tip/sleeve) output to be patched with single conductor shielded cables.
(18) HIGH OUT JACKS
Again, as per previous crossover discussion, this 1/4" jack supplies high frequency out signals from
the activated crossover for patching to this amplifier and/or additional power amplifier inputs. Unlike
the low-frequency crossover output, that is automatically routed to the associated channel, the highfrequency
output signal must be patched to some suitable input in order to complete the biamped
system. This 1/4" jack also provides an unbalanced (tip/sleeve) output to be patched with
single-conductor shielded cables.


See? Easy init? :p

so the way your band proberaly did it was to run mono! 1 channel on bass the other on mid/hi

[Excalibur]

This is taken from the PV1500 manual!

CROSSOVER SWITCH (150 Hz XOVER
This switch is used to activate the 150 Hz crossover for the corresponding channel. It is also a pushpush
type switch and requires a small “tool” to activate. The PV® offers two 150 Hz crossovers. These
are specially designed features that enhance the response of most loudspeakers in a typical bi-amped
application. Rather than just having a flat output curve, these crossovers use special filters to tailor the
response and provide a flat acoustical output. This type of crossover “sounds” more natural than
conventional “state-variable” type crossovers.
With the switch IN, the input signals are routed through the crossover, and the low frequencies are
automatically sent to the corresponding channel. At the same time, the high frequencies are sent
to the HIGH OUT (18) jack and must then be patched to INPUT of the other channel of this amplifier
or to another amplifier input to complete the bi-amped system. Additionally, the low frequencies are
sent to the THRU/LOW OUT (17) jack, and can be patched to other amplifier inputs to permit even
larger systems. With the switch OUT the crossover is defeated, and the input signal is routed directly
to the respective power amp channel. The crossover frequency is fixed at 150 Hz and cannot be
changed. The crossover configuration is a 4-pole Linkwitz-Riley approximation.
(17) THRU/LOW OUT JACKS
As per previous crossover discussion, this 1/4" jack supplies low-frequency out signals from the
activated crossover for patching to additional power amplifier inputs, providing added flexibility in
larger bi-amped systems. When the crossover function is not activated, this jack converts to a THRU
function, where the output of the electronically balanced input circuitry is supplied to this jack. The
THRU function provides the means to patch a full range input signal to the other input of this
amplifier (parallel mode), or to other amp inputs in the same rack. This function allows one balanced
mixer feed to be connected to the amp via the desired balanced input connector (XLR, 1/4", Barrier),
and then further distributed locally. Regardless of the crossover switch position, this 1/4" jack provides
an unbalanced (tip/sleeve) output to be patched with single conductor shielded cables.
(18) HIGH OUT JACKS
Again, as per previous crossover discussion, this 1/4" jack supplies high frequency out signals from
the activated crossover for patching to this amplifier and/or additional power amplifier inputs. Unlike
the low-frequency crossover output, that is automatically routed to the associated channel, the highfrequency
output signal must be patched to some suitable input in order to complete the biamped
system. This 1/4" jack also provides an unbalanced (tip/sleeve) output to be patched with
single-conductor shielded cables.


See? Easy init? :p

so the way your band proberaly did it was to run mono! 1 channel on bass the other on mid/hi

Not quite. It looks as if I misunderstood which amp ran which set. If I read the manual correctly, the Peavey gets the low frequency and the high is the output sent to the other amp. Also it is posible to feed another amp with low frequency as well. That's how I read it.


Note: Having scrolled further down on the manual, there is a schematic diagram showing exactly the setup I have just described.

http://www.swee****er.com/store/media/pv1500_doc_manual.pdf

( sweet water) censor doesn't like it when they are together.

Apart from getting the amp frequencies about face, it appears I was right. Easy, innit?

[gillo]

if your going to use your full range cabs then make sure you disconnect the horns!

[bluishbob]

I don't think i will bother running subs at all, i will just run both systems as mid/top.

But what are your thoughts on running the peaveys 4ohms bridged. It may be running 2ohms in effect, but its a professional amplifier and it shoutldn't in theory cause a problem. Plus, they do advertise that it is suitable for this application (bridged 4ohms)

[Excalibur]

I don't think i will bother running subs at all, i will just run both systems as mid/top.

But what are your thoughts on running the peaveys 4ohms bridged. It may be running 2ohms in effect, but its a professional amplifier and it shoutldn't in theory cause a problem. Plus, they do advertise that it is suitable for this application (bridged 4ohms)

Indeed they do, but I would regard 8ohms bridged/4ohms per side as ideal. Heat dissipation would be vital at lower levels, and I would regard this as running on or near the limits. If your amps were big enough, two pairs / one amp gives 4ohms per side, bingo. This is in effect how my large PA runs.

[nigelwright7557]

I run a 500 watts rms amp with 1000 watts rms of speakers.

Doing it the other way around is gonna end up with an expensive repair bill !

Unless you know what you are doing I would leave it to the experts.

[Solitaire Events Ltd]

Unless you know what you are doing I would leave it to the experts.

And I'm sorry to say that most of your advice seems to go against what the experts say.

[Excalibur]

And I'm sorry to say that most of your advice seems to go against what the experts say.

True enough, but this seems to be the most recurrent thread on here, with the least agreement! The only concensus is to keep it green everywhere!