Question on Resistance.

mc_bob

mc_bob

mc_bob

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Ok it's a Q for my friend.

He has an amp which is rated 12-16 Ohms for 4 speakers and 6-16 Ohms for 2 speakers.

Will it be harmful to run 4 speakers which are 8 Ohms each?

Thankies.
 
It is possible it would cause damage to the amplifier and/or speakers themselves. Really it depends how loud you have the amp. If it was on suitably quiet, then it may be fine as it would still be within it's power rating. As you turn them up, the smaller load will try to take more current and thus power, in doing this you may overheat the amplifier and as it struggles, the clipping it is likely to produce could damage the speakers too. Best not to risk it imo.
 
'tis possible to overheat the speaker coil with an underpowered amp.
so I guess it depends if he's likely to rag it or not.

if it's a cheap amp, it's also likely to overheat

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(edit)
darn, beaten to the post :)
.
 
LOL. He now asks if you can make the resistance higher lol! By adding a resistor or something lol.

Thanks
 
It'll just be quieter :p


I'd guess he wants to drive four speakers in a 2 x front / 2 x rear setup ?

but he might be better off just driving the 2 front ones off the Amp, and the rears off his head unit (the rears are only for infill anyway)

.
 
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Possible solution:

Put 2 8ohm in series per channel to give 16ohm load on each channel, so you power the 4 speakers without overloading it. This is just assuming it's a stereo amp which for some reason you need to run 4 speakers from (multi room?) as naturally the 2 speakers in series on each channel will produce identical output. This works theoretically, but i'm not certain it's ok with crossovers etc :confused: . Should be though :)
 
Ok thankies.

There is one more question !

What about, from the amp going into another power amp. He wonders if he can drive his Subwoofer off it?
Will the resistance matter?

If it does, can he connect the power amp in series to the first set of speakers? As it isnt draining any (I think) energy.

thanks
 
Not sure I undersatnd that fully. You can't run another power amp from the output of the first power amp, its input will be severly overloaded. If however you have a preamp and wish to run 2 poweramps from it's output, that should be ok. If these poweramps are actually integrated amps (ie with volume controls and input selectors), you may be able to use a tape/monitor out from the main amp into the subwoofer power amp. Of course you'll only use one of the channels on the amp to power the sub, unless you use it bridged. I may be way off with what your proposing, if I am, mabye a diagram would help (just in paint or something) :)
 
Ok lol, Ill bodge a piccy up.

setupyu6.jpg


He can just use one of the Subs, but he does have two. I think itll be better with just one, but is there any way of sorting it out?

If it is plugged into the tape out socket, will the volume control affect it?

thanks
 
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It's an active sub? I'm not sure on the tape out, but it probably doesn't actually. Can the sub accept speaker level inputs as well as line? If it could you can try that. Is this the same setup btw, with 2 speakers on each side?
 
It's not relevant on passives. To add the subs, you'll need another amplifier, or you could fit a plate amp in the sub(s) to make it active. You can pick up stereo integrated amps cheaply from an auction site, but for subs your probably looking at the higher power output ones, which will cost more. Are the subs really essential though? How big is the room, what speakers are the fronts? Are you still using 2 sets on each channel? Your freind is trying to set up a very unorthodox system with all these speakers, a good pair of floorstanders at the front seem the best option really.
 
He doesnt want to change his Amp currently, nor the speakers.
He was just wondering as he has the subs left over from a set-up before.

So can he wire them up to the first output aswell as the speakers? If they are active will it affect the speakers?

Thanks
 
If they are passive I don't think they can be added as is. I expect they are 8 or possibly 4 (if car type subs) ohms? This means in parallel, the resistance on any channel would drop to under 8 or 4 ohms and the amp won't be able to handle it (this is still the setup with 2x8ohm speakers in series each side giving 2x16ohm loads?). In series, the added resistance of the sub makes the resistance on the channel(s) over 16ohm and increases the risk of damaging oscillation. Either of these methods are fundementaly flawed, but could work; however in either case you'll have the problem of the sub level being fixed and thus no control over the bass level. Generally a sub will need more power than the main speakers, so the bass output added by the sub would likely go unnoticed. So, you must make the sub(s) active if you wish to add them, otherwise I wouldn't try to :)
 
Yup lol. He was planning to hook them up to another amp.
Where would he wire them to? We're both confused lol.

Thankies.
 
If it's a Denon PMA-320 HiFi Amplifier
then I think it has two sets of speaker outputs ?
(look for 8 speaker sockets on the back)

so you could just connect the sub to the switched set.
(then try it without the sub, as it may sound worse with one)

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If you want to use the other amp to drive a sub, then connect the tape out from one amp to the aux input of the other
(as suggested already)

you may have problems getting it balanced though.
 
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