How to wire speakers properley to an amp

[James_Huxter]

I am pretty new at wiring speakers properly, I am trying to wire 10, 20 watt 8 ohm speakers to a 30 watt amplifier.
speakers: http/w.mawebcenters.com/midwestspeaker/ecommerce/speco-sp-502a-5-1-4-2-way-in-wall-ceiling-speaker.html
amp: cant find a link for it online but i have this:
SHOW Solid State Public Address Amplifier
OUTPUT max: 30 watts
speaker inputs: COM 4 8 16
line: 25v or 70v

I was just wondering if anyone could help me out in trying to explain to me how to wire it properly so i don't blow anything

 

[photonboy]

What exactly is the problem?

The speaker wires are labelled clearly to show which position (+ or -) to use.

1) s that 30W max per output or the TOTAL max?

2) And, do you actually have ten speaker connections?

3) I'm not sure what the "COM 4 8 16" means though and I'm no expert. Is that for OHM? If so, set to 8OHM.

*You really should have a manual for the amp.

 

[ssddx]

if you have ten 20w speakers then you need a 200w @8ohm amp if you expect to play them all at once. a 30w per channel with ten channels amp would work but not a 30w total.

here is how to set up a PA system. https/www.youtube.com/watch?v=MmHvvf8UKfs

 

[americanaudiophile]

To do what you want to correctly you will need to get one of these for each speaker:
http/www.lashenelectronics.com/p-551-bogen-t72510-25v-or-70v-10-watt-speaker-line-matching-transformer.aspx
That will allow you to connect all the speakers with a single two conductor run of speaker wire which can go from the amp to the closest speaker and then from that one to the next closest and so on.
Since you have a total of 30 watts and 10 speakers you would select the 2.5 watt connection on the transformer so that all the speakers will get equal power. Connect to the 25v or 75v connections.
If you want to use the regular speaker taps rather than the 25 or 75v outputs then you will have to connect three speakers in parallel (+ to +, - to -) and then connect each trio in series (+ to -, - to +). Connect the last speaker in series. Connect to the com and 16 ohms connections.

 

[tomc53]

To do what you want to correctly you will need to get one of these for each speaker:
http/www.lashenelectronics.com/p-551-bogen-t72510-25v-or-70v-10-watt-speaker-line-matching-transformer.aspx
That will allow you to connect all the speakers with a single two conductor run of speaker wire which can go from the amp to the closest speaker and then from that one to the next closest and so on.
Since you have a total of 30 watts and 10 speakers you would select the 2.5 watt connection on the transformer so that all the speakers will get equal power. Connect to the 25v or 75v connections.
If you want to use the regular speaker taps rather than the 25 or 75v outputs then you will have to connect three speakers in parallel (+ to +, - to -) and then connect each trio in series (+ to -, - to +). Connect the last speaker in series. Connect to the com and 16 ohms connections.

Almost right -- if you use transformers, they must match either 70v or 25v (25v is almost unheard of these days).
Alternatively, you could use 5 transformers and put two speakers on each one. Use the 5watt tap and the 4ohm output to to speakers in parallel (all + together, all minus together)

For transformers you can use smaller wire between the amp and the transformers - #22 or #24, even CAT5 if you have it lying around. If the transformers are less than 10 feet from the speaker, you can use the same wire, if not you should go to at least #16.

If you wire without transformers as americanaudiophile suggests, the load on the amp would be fine, but you would be blasted out by the single speaker and barely hear the other nine.
If you want to not use transformers, you could hook them paralleled in 5 sets of two in series - kind of like this
. . . . . ________________
. . . . /. . . |. . .|. . .|. . .|. . .|
+ . ./. . .+|. . .|. . .|. . .|. . .|.+
__/. . . . .S. . S. . S. . S. . S
__ . . . . . |. . .|. . .|. . .|. . .|
. . \. . . . .S. . S. . S. . S. . S -
- . . \. . . . |. . .|. . .|. . .|. . .|
. . . . \___|__|___|__|___|

keep all + terminals toward the top and you should be ok. this is a 3.2 ohm load so use the 4 ohm terminals. It a little low, but within range for this type of amp.

I know this is a little hard to actually do in place, but draw it out on a map of the room, and you'll do fine.
If you are less than 20 feet between speakers, you can use #16 wire. if longer, you should use #14.

You could also mix transformer and direct but the calculations get intense. It is only worth it if you have a large area to cover, and probably more than you need.

 

[tomc53]

What exactly is the problem?

The speaker wires are labelled clearly to show which position (+ or -) to use.

1) s that 30W max per output or the TOTAL max?

2) And, do you actually have ten speaker connections?

3) I'm not sure what the "COM 4 8 16" means though and I'm no expert. Is that for OHM? If so, set to 8OHM.

*You really should have a manual for the amp.

Not to squelch your enthusiasm, but if you don't understand the question, you may want to either ask for mor details, or do some research yourself before commenting. I know you are trying to help, so FYI:

1. PA amps usually have only one output, so the total would be 30W. There are some specialty amps with 2, 4 or more outpus, used for 'zoning'.
2. techically 5 connections, sharing a single common return (sometimes called neutral or ground). In most cases you would only use one connection, and split it up as below.
3. "COM 4 8 16 25v 70v" are the connections giving output impedance options for the amp, and for a single speaker you would match to the impedance of the speaker, which could be 4, 8 or 16. Some speakers come with a transofrmer pre-mounted for 25 or 70v.
For multiple speakers, you need to do a little math --
For series connected ( +_s__s__s_- ) you just add the impedances. (8+8+8=24).
For parallel, if they are all the same, just divide (3-16s in parallel would be 16/3=5.3)
If you read my other reply, 2 in series would be 8+8=16, and 5 pairs in parallel would be 16/5=3.2.
The line outputs are rated on voltage and expecting transformers to get to speaker level.
In that case you pick the taps on the transformer to match the speaker and line tps so that the total does not exceed the max allowed. Tou can even use different taps, for speakers which need to be louder, like a high ceiling, or softer, like in a bathroom.
And finally, you can mix the low voltage and hgh voltage outputs on the amp, but that can get pretty complex.

 

[tomc53]

if you have ten 20w speakers then you need a 200w @8ohm amp if you expect to play them all at once. a 30w per channel with ten channels amp would work but not a 30w total.

here is how to set up a PA system. https/www.youtube.com/watch?v=MmHvvf8UKfs

Whoa - wrong assumptions and calculations.
Twenty watts would be maximum that each speaker would handle. There is no rule that says you must push them to that limit. You always want to actually USE less power than the speakers can take, and that the amp can deliver, otherwise you will get distortion at best, or at worst equipment failure. In practice a couple of watts can be pretty load, expecially for background music or announcements, where a little distortion is acceptable.

Check out my other comments to get more calculations for multiple speakers.

For example a typical speaker may have an efficiency rating of 90dB at 1watt, 1Meter (about 3 feet). As watts go up, it gets louder (10db for 10X power), and farther away, it gets softer (-10db for 10X distance). So for 32 feet (10M) from the speaker, you would need 10 watts for 90dB, 100W for 100dB. 100dB will do permanent hearing damage, and is only needed in a rock concert, not for background music. In fact, 50dB is probably too loud for background music, and 70dB is plenty for announements. With this speaker, at 32 feet, you would only need 1/10 watt for 70db.

Information is power, and experience is still the best teacher.

tom...