Question for audiophiles on speaker/amp hookup

[Argentina94]

I own a 5.1 receiver. While I'd love a 7.1 and would solve my issue the way it should be, I can't get one just now.

Anyway, mine is a Technics Digital-Ready receiver with an SH-AC500D Decoder. I currently use an actual 5.1 speaker setup with two towers for fronts (150 watts), a Center (150 watts) and two old bookshelfs for surrounds (40 watts).

I just bought on sale a pair of small 2-way bookshelfs which read 5-100 watts power handling. All my speakers are 8 ohms.

I was wondering if I can connect these new bookshelfs along with the bookshelfs I already have to have a pseudo-7.1 setup. I know it's not ideal but I do like how the extra set of speakers give a more enveloping sound quality.

My question relates to the amplifier and if I run any risks of damaging any of my components.

Thanks.

 

[Neo Ash]

Linking the speakers and running them in what is know as a parallel configuration will alter the ohm load the amp has to push.

This type of configuration is used in pro-audio. But in that situation the amps are designed with that in mind. Therefore those amps have variable ohm settings.

 

[Argentina94]

Linking the speakers and running them in what is know as a parallel configuration will alter the ohm load the amp has to push.

This type of configuration is used in pro-audio. But in that situation the amps are designed with that in mind. Therefore those amps have variable ohm settings.

My amp states 8-16 ohms for surround. The rest state only 8 ohms.

In other words: bad idea?

 

[Neo Ash]

My amp states 8-16 ohms for surround. The rest state only 8 ohms.

In other words: bad idea?

If your current speakers are 8 ohm and the new ones are 8 ohm, they should run safely. The amp should be set to 16 ohm.

 

[Neo Ash]

Now, on the subject of 7.1. To be honest it doesn't wow me that much. 5.1 is still the standard for surround and will be for a while to come. 7.1 will not make 5.1 disappear over night like Dolby Pro Logic did.

 

[smokehouse]

Sorry for the shit drawing. If you want to wire two 8-Ohm speakers together for 16-Ohms combined at the amp, follow the Series diagram. DO NOT wire them parallel as it would come in a 4-Ohm and likely burn up your amp (or make it run hot as hell)…

Remember, this is ONLY if the speakers you want to run are ALL 8-Ohm.

 

[Argentina94]

Sorry for the shit drawing. If you want to wire two 8-Ohm speakers together for 16-Ohms combined at the amp, follow the Series diagram. DO NOT wire them parallel as it would come in a 4-Ohm and likely burn up your amp (or make it run hot as hell)…

Remember, this is ONLY if the speakers you want to run are ALL 8-Ohm.

Yes, they are 8 ohm.

Basically, I want to wire two sets of surround speakers on my 5.1 setup.

So you suggest the positive on one speaker and negative on the other go into the amp then I wire the remaining open inputs to each other (negative on one speaker to positive on the other speaker)?

Do I run any risk on the amp if it states 8 ohms on the speaker output of the receiver and not 16?

 

[smokehouse]

Yes, if your amp is NOT rated for 16-ohm, don’t wire it that way. No, it won’t burn up an amp like taking the Ohm level lover than rated but it will under power your speakers. If your amp is only putting out 40w@8-Ohm, 16 would be even less.

This is not exact science but the following is what will happen:

Original rating:

40w@8-Ohm

Take that down to 4-Ohm and you’d see this:

80w@4-Ohm

Take your resistance to 16-Ohm and it would look like this:

20w@16-Ohm

Higher resistance = less power (again, those #’s aren’t gospel, I just used them to make a point).

Sounds like lower resistance is good huh? Not if your amp isn’t rated for it. It will overheat and often to the point where it will burn up the amp.

If your amp is rated for 8-16 Ohm then you are in the clear. I had an older JVC amp that was like that…







BTW...7.1 is not all it's cracked up to be. First off, there are no 7.1 encoded discs. Hell, the only format that isn't 5.1 is DTS ES, it is the only discrete 6.1 format that comes encoded that way, not even Dolby Digital EX boasts that (rear center is matrix, not discrete)...

Now the new formats coming out can support many channels…

 

[smokehouse]

So you suggest the positive on one speaker and negative on the other go into the amp then I wire the remaining open inputs to each other (negative on one speaker to positive on the other speaker)?

I know it sounds confusing but that's the way to wife 2 8-Ohm speakers to get 16-Ohm. Follow the power coming from the amp, it leaves the positive terminal and goes to the pos terminal of speaker 1. It then goes through the speaker and leaves the neg terminal of speaker 1.

(Still following me?)

Normally you'd take the line to the neg on the amp...8-Ohm. But, you take that power and pump it into the Pos terminal of speaker 2. It goes through the speaker and out the neg terminal. Now take it back to the amp, 8+8=16-Ohm.

The other way (parallel) you'd have two 8-Ohm speakesr wired directly to the amp. Following mathematics for a Parallel circuit, 1/8 + 1/8 (first speaker + second speaker) = 2/8. Take the reciprocal of that 8/2 = 4...you'd have 4-Ohm.


Here’s the way it would look on paper, R1 is speaker 1 and R2 is speaker 2. In a circuit, a speakers is “seen” electronically as nothing more than a resistor. (again, shitty drawing but the red "squiggly" things are supposed to be the symbol for a resistor).

 

[Argentina94]

Ok, I fully understand (really, I do!)

Now, both speakers are rated 8 ohms and I was misinformed earlier, it's the fronts that allow 8-16 ohms but the surrounds are strictly 8.

Now, the receiver outputs 100w x 5. One of the bookshelfs I use for surround has a max rating of 60w and the other is 50w.

Since the total is only 110w, would that help offset the fact that at 16 ohms the amp is only sending half the power to the speakers?

And no, I've never had an interest in a 7.1 speaker and don't really need the extra surround for my curent setup, but I just wanted to try out putting one surround a little in front of me with another a little behind me.

Do you suggest another way of me placing the surrounds? I realize it won't make much of a difference since the same signal is being sent to both speakers. Both sound very nice on a bookshelf system and while one is 3-way, the other is 2-way.

 

[smokehouse]

I’ll address that in a few steps.

Concerning the 100w amp and 60w speakers thing, that’s rarely a problem. It’s far easier to burn up a speaker with too little power or distorted power than it is to burn one up with too much, most home amplifiers simply don’t make that kind of juice (now car amps…that’s a different story). The power output of your amp is not a constant 100w, I’d be willing to say that you probably rarely use you amp at more than 50% rated power.

Think of it this way, most TV’s have tiny speakers and a small internal amp (7-10w…some “deluxe” TV’s might go up to 15w). Think of how loud you can turn a TV up and that’s with only 7-10w.



On the other topic, you can try hooking them up in pairs but it will probably half your amp’s output. While not a big deal on paper, it will throw them completely out of balance with your front 3 speakers in terms of SPL. To have your system functioning normally I try to keep all of my speakers (including the sub) within 1dB of each other.

That will be really hard to do if you half your power to the rears. Adding another speaker will give you 1-2dB gain but, half-ing the power will ding you 3-4dB. You will notice the difference in volume loss. That’s why the “8-16 Ohm” rating is important. If they were rated for that, the manufacturer is stating that at these Ohm levels, this amp will stay within the normally power ratings. If not, it will cause power loss.


Sorry for the long winded response…