Does it matter if the ohm load is different on individual channels of a 4 channel amp

jeffandpamsmith

I have an old Sound Craftsman Pro Power 10. 4 channel workhorse. 200watts per channel @ 8 ohm, 400 @ 4 ohms, and I read somewhere on this forum is can handle lower ohm loads.

My question is: if I run 2 of the channels at a lower ohm load (2.66-3...just for discussion), will it help the amp in general to run the other 2 channels at a higher ohm load, or are all 4 individual when it comes to overloading (ie my choice for the other 2 channels are 4 ohms for a parallel hookup or 16 ohms for series)?

TECHNOKID

Jeff, the higher impedance are usually easier on the amplifier and this is good especially when the amp is aging. On other forum you have been asking questions on paralell and series connections. Paralell is usually a threath to amps as it lowers the overall impedance (I fixed many amps with blowned outputs that were caused by such arrangement). Series arrangement are not as much of a threath but will lower the overall output of each speakers. Series/paralell combination is good as you can manage to balance the average impedance to what it is supposed to be however, you have to realize that there also you will loose some power at each outputs (series = voltage drop while paralell = current drop and P = ExI). Your best bet is to keep each O/P balanced at the same impedance and play with some series/paralell arrangement if you need more speakers than the actual amount of O/P available. I would suggest using maybe 8 ohms impedance setting since 4 ohms while providing greater O/P power will also generate more heat at the amp since it is working harder.

Cheers and good luck!
TK

AudioGenics

you could use speaker line transformers to match the loads.

TECHNOKID

jvc wrote: »

you could use speaker line transformers to match the loads.

definitely another option however, the more components means greater lost. The use of Matching Xfo is normally with paging PAs, rarely seen them use in home. If the bimpedance balancing is feasable using the series/paralell arrangement it should be the easiest and most effective way to go about it. Jeff, are the speakers ceiling mounted?

Cheers!
TK

jeffandpamsmith

for only $150 more I would have 4 speakers/channel, at 8 ohms, in series/ parallel to present each channel with 8 ohms to power 4 speakers with 200 watts. for what I want, I would think this would be plenty of power and the extra speakers would fill the area better and not have to be as loud to do so...is that right?

TECHNOKID

jeffandpamsmith wrote: »

for only $150 more I would have 4 speakers/channel, at 8 ohms, in series/ parallel to present each channel with 8 ohms to power 4 speakers with 200 watts. for what I want, I would think this would be plenty of power and the extra speakers would fill the area better and not have to be as loud to do so...is that right?

In order to properly reply to your statement, it would be nice to know exactly what you are trying to achieve but a quick answer is yes. The more speakers that are spread in a room, the less power required to achieve the desired ambiance and therefore less stress on the equipment overall. However, you want to consider the rating of the speakers accordingly to match the power of the amp.

Cheers!
TK

jeffandpamsmith

http://www.ticcorp.com/omni_speaker_gs3.htm

This is the link for the outdoor speakers. Not that efficient, but well made, used at Disney, Busch Gardens etc. and all I want is quality sound at nice ambiance volumes not party volumes. Covering a fairly big, open, waterfront back yard with no obstructions of note to block sound. As far as covering the area with enough sound: 6 speakers would be plenty (2.7 ohms), 2 cranked up just a bit may even do it (4 ohm), but 8 would give 8 ohms load (series-parallel mix). and the amp has 200 watts/channel so I think it would be planty of clean quality volume for what I want. This would cost more speaker wise, but I'm guessing 8 speakers would give better bass and sound in general in this situation since more drivers would be vibrating...is that sort of right (as opposed to 4 speakers with more watts turned up higher, still easy for the amp but less speaker comes moving to produce sound).

The 2 indoor channels are the Polk Monitor 5's, from the other post - I don't know the ohms. I remember at buying (decades ago) being told 6 ohms, the Polk site from this forum says 8, and my speakers don't say "5B" or anything. I know for sure the other 2 channels have the power to run them in series @ 12 or 16 ohms if that protects the amp, but it would be very hard to match the impedence load of the outdoor set. They would be coming off 2 different preamps BTW, so would have sep. volume controls.
Can I test speaker ohms with Radio Shack meter? I have an old one, and would have to have them tell me how to set it. Will that answer the Polk 5 impedance question?

Maybe I should just buy 4 Omni speakers for now, try them, and if they dont cover the area sound wise, try mixing the combos of 2,3 or 4 speakers just using a single channel to see how the amp handles the load, then but another 2 or 4 speakers depending on my findings. I really think 6 total would be perfect for the yard, 8 total overkill, but for only $150 more it may be the safest bet...hey, maybe I'll only need 4 total after all!

McLoki

With a good amplifier no - it does not matter that the impedance of each speaker match. if you are are using a less than stellar design though (like many AVR's) I would not risk it. (or call the manufacturer and ask)