Speaker problems

[Drillmn300]

I have 2 wires each going to speaker A, B,C & D speakers C & D work great and I have a short in the wire on speaker B. When I hook up speaker A I get nothing and the same for B and I have put them on separate amps as I have 3 of them and get nothing out of them. I have checked the wiring on the back of the speakers and nothing is crossed on any of them. I ran a continuity check on all of them leaving the amps and speaker B showed continuity but it does not connect to speaker A anywhere.

Everything worked when I used it Thursday evening but only half the house when I turned it all on Friday night, I have switched out the mixer, tried all the rca plugs on each amp and even tried an extra amp I had laying around just for giggles. They were nice enough to tape the wires all the way across the ceiling so I can't just pull one and replace it so I will have to pull them all or send someone up in the ceiling area.

I am not that great with working on these and have exhausted myself on ideas, any help would be appreciated.

thanks

[Popeye]

Are you sure speakers a and b are good? You said you have a short in speaker b. Did you fix this?

[wepauls]

AN old timer toll me test speakers use a volt battery to test them

just a thort

[Drillmn300]

I think they are blown so I just ordered new ones for $2,000.00 they are about 10 years old so time to upgrade anyway. I am thinking the short is because they are fried as I do play music very loud as I want people to know they went out. I have a feeling whoever turned them on for the radio on Friday didn't lower the volume from the Sorority party the night before and blew them both.

anyway thanks

[wepauls]

IS that for the hold center as two kits of 10 or more speakers each , or just two speakers

[Ted]

The resistance should be within 10% of the rated ohms stated on the speakers. Set the meter to low range ohms and test right across the speaker terminals. Most are 8 or 16 ohm speakers.
Some systems series some speakers to keep the impediance the same. In other words, you could have 16 ohm speakers for mid range. Each has a 2 conductor.
If the subs are 8, they can be put in series to equal 16 ohms. These too could have a 2 conductor going to each, but at the amp, one wire from each is tied together. 4 subs in this setup still have 2 outputs.
So if one speaker in the series was bad, neither would work.

[Drillmn300]

Thanks Ted that answers one of my questions as now I know how to read them at the speaker, Wepauls that is for 4 speakers and we use 8 so will replace these for now and probably upgrade the other 4 later this summer so they all match. I have a huge party this weekend so just ordered enough to get me by and back on track with sound.
I get everything from a guy I have been purchasing industrial electronics off of for a long time so it cost a little more but the sound is unbelievable.

[Drillmn300]

They must have been blown as I put new ones in today and all is back to normal, the new ones really sound impressive.

[toon30s]

Drill, my dad had a similar problem a while back. He had a speaker blow and took out one chanel of one of his amps. Glad you got your problem fixed.

Ditto to Ted, thanks for the explanation on reading ohms on speakers!!

[SoCalTom]

Speakers and amps are finicky things. Speaker impedance should be matched to the amp. If an amplifier is rated at 8 ohms, and I have four 8 ohm speakers, I'll wire them in a series-parallel circuit. Two speakers are wired in series, then the other two are wired the same. then the two cables from each pair are wired in parallel. This will present an 8 ohm load to the amp.

Here is an example of a series-parallel circuit.....



Personally, in a large venue, such as a bowling center, I'll use self-powered speakers. (The amp is built into the speaker cabinet.) Then, those speaker systems can be driven from the line output of the mixer. Each speaker's volume control can be set for enough loudness to cover that particular zone. Also, at line level, each speaker system will be wired in-phase, making for complete coverage without dead spots.

[JACKO]

SoCalTom, Thanks for showing that diagram, that is actually how we did our last speaker upgrade. I have seen more power speakers lately, and have been interested in them. That really "SOUNDS" like the way to go!

[SoCalTom]

Jacko - what's really great about self-powered speaker systems is that speakers can be located anywhere in the center, including the bar. You can set the lane speakers at "blasting," while speakers in other zones (like the bar) can be set to lower levels. Another thing is that each speaker system can be turned off without upsetting the balance load to the amplifiers.

BTW: There is a difference between impedance and resistance, although both are measured in ohms. An 8 ohm speaker's resistance can measure anywhere between 7 and 10 ohms. This is due to the voice coil of the speaker. To accurately measure the impedance of a system, an impedance bridge is required. An ohm meter will measure continuity only.

Another BTW: Using self-powered speaker systems, a distribution amp should be used. This would make certain that each speaker system receives a constant signal level through long cable runs. Getting technical, the velocity factor of the cable should be taken into consideration. The velocity factor is the resistance and impedance of the cable. Since electron flow is slower than light speed through a cable, the cable imparts a resistance to electron flow. The longer the cable, the more resistance. This, in effect, imparts an impedance mis-match. In essence, high frequencies will sound muddy. At audio frequencies, an impedance of near zero is recommended. The higher impedance of a cable will, in effect, reduce the higher audio frequencies. Basically, a low impedance balanced microphone cable should be used for long (up to 1,000 feet) cable runs. Since low impedance microphone cable is shielded (and the shields are run to a common earth ground), hum and noise is virtually eliminated.

[SoCalTom]

One more thing, since it's too late to edit, between a mixer and self-powered speakers, a compressor (of sorts) should be considered. Behringer makes excellent low cost compressors; however, the best of the business is an "Optimod" from Bob Orban. That guy is a genius when it comes to audio. In fact, the guy holds several patents for his designs. (He's to audio what Steve Jobs was to Apple; and Bill Gates to Microsoft.)

An Optimod for a desktop computer is possibly the best you can get, for keeping audio levels constant and sounding excellent. Unfortunately, his equipment is priced out of bowling center systems; as the computer card (and associated software) sells for slightly under $10,000. (His stereo Optimods for radio and TV stations run in the $25,000 to $40,000 price range.)

Basically, a compressor in the audio chain keep the mixer's signal from overloading the amplifiers in the system; and prevents the amp from blowing out speakers from extremely loud passages and transients.