PA speaker question

 

New member
Username: Erickat

Post Number: 1
Registered: Jun-05
I have a peavey mp-4 mixer amp rated at 50 watts per channel hooked up to speaker cabinets that consist of separate bass / horn units, each rated at 8 ohms (horns are 30 watt EV units, bass (pl-15's) are mtx 150 watt units ) each unit has a + and - input, like a regular speaker, so I run a 1/4 inch cable out from the amp to a female 1/4 inch jack that splits into a + and - wire. I put the + into the horn box & the - into the bass box and cross-over from the - horn to the + bass. There is a low pass filter in each horn. problem is - the amp is rated at 50 watts at 8 ohms - but isn't my load 16 ohms the way I have it set-up? It sounds OK at low volumes but even half-way cranked up, it distorts badly. 1) will this damage the speakers? 2) will it damage the amp?
Thanks - I know this is more of a professional sound reinforcement question.
 

Silver Member
Username: Thx_3417

Bournemouth, Dorset United Kingdom

Post Number: 196
Registered: May-05
Eric

That's ok welcome

Hallo there.

EV is a good PA make

Yes it will indeed damage the amplifier with excessive use in the way you described, look for an amplifier that as around 300watts for each channel and rated at 8 ohms, and if you would like to have less distortion then an electronic active X-over unit two-way as you are running LF low frequency and HF high frequency compression driver.

With an active X-over the low frequencies will be free from high frequencies and the high frequencies will be free from low frequencies, thus less distortion greater dynamic range.

2 stereo amplifiers will be needed for "active X-over" applications one for each channel.

So in the mean time don't push the volume above the level where it is cursing distortion.

Easter egg extras
http://www.dod.com/crossovers/sr835.htm

http://www-personal.engin.umich.edu/~jglettle/section/rapture/activexover.html

http://www.dancetech.com/aa_dt_new/pa/PA.cfm

http://sound.westhost.com/project09.htm

http://www.in70mm.com/newsletter/1997/51/thx/life_with_thx_1.htm
If you turn off the "THX Monitor", the device which also contains the THX crossover device, you lose ALL sound, and you will quickly be notified of BIG problems with your show! With the advent of the new digital processes -- all of which can deliver a "knockout punch" to your speakers if you let them! -- we have had much more trouble with speakers than we did a few years ago.
The most common problem is a damaged high-frequency driver. If this happens to the center channel, you can lose all intelligibility of dialogue and may have to shut down to replace it. (Virtually all dialogue comes through the center channel.) The most notorious recent event like this happened next door at the Chinese Theatre (thank God!), during the invitational premiere of Schwarzenegger's "Eraser". A loud sound of some sort, in the middle of the film, burned out the high frequency driver of the center channel. Dialogue was totally muffled, being heard only through the low frequency (below 500 Hz) components of the center channel.
Needless to say, within seconds, dozens (or so it seemed) of Warner Brothers executives were in the projection room, and...well, it's not a situation you'd ever want to be in! Usually, failure isn't so catastrophic that we must shut down, and we can replace the problem driver during an intermission (if time permits), or the following morning.

http://www.thx.com/news/20050316B.html

http://www.shorefirerecording.com/images/6290Amp.JPG

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http://images.google.co.uk/imgres?imgurl=http://www.lansingheritage.org/images/j bl/specs/pro-speakers/thumbs/urei-81x_small.jpg&imgrefurl=http://www.lansingheri tage.org/html/jbl/specs/pro-speakers/pro-speakers.htm&h=184&w=140&sz=7&tbnid=6iS AkTO12_wJ:&tbnh=96&tbnw=73&hl=en&start=2&prev=/images%3Fq%3Djbl%2Burei%2B%2B%26h l%3Den%26lr%3D%26sa%3DN

http://images.google.co.uk/imgres?imgurl=http://www.lansingheritage.org/images/j bl/specs/pro-speakers/thumbs/urei-81x_small.jpg&imgrefurl=http://www.lansingheri tage.org/html/jbl/specs/pro-speakers/pro-speakers.htm&h=184&w=140&sz=7&tbnid=6iS AkTO12_wJ:&tbnh=96&tbnw=73&hl=en&start=2&prev=/images%3Fq%3Djbl%2Burei%2B%2B%26h l%3Den%26lr%3D%26sa%3DN


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