4ohm speakers and a 8ohm reciever.

[Powripper]

One of my roomies recently wanted to hook up a 6.1 or 7.1 system for the tv downstairs, now she got a sony 6.1 reciever (pretty cheap) but the build quality seems decent. Now it is rated at 100 watts per channel at 8 ohms, it doesnt seem to have listed a minimum impedance, nor does it have any type of impedance selector on tha back (which I have heard are usless anyways)
only problem is that it seems the speakers she got are all 4 ohms and the fronts are quite large and require alot of power. will this reciver be ok? and is there any possible way of adding an amp to the reciver?
I'm not sure of the best way to go about this so any advice would be very helpfull.

 

[Flerbizky]

One of my roomies recently wanted to hook up a 6.1 or 7.1 system for the tv downstairs, now she got a sony 6.1 reciever (pretty cheap) but the build quality seems decent. Now it is rated at 100 watts per channel at 8 ohms, it doesnt seem to have listed a minimum impedance, nor does it have any type of impedance selector on tha back (which I have heard are usless anyways)
only problem is that it seems the speakers she got are all 4 ohms and the fronts are quite large and require alot of power. will this reciver be ok? and is there any possible way of adding an amp to the reciver?
I'm not sure of the best way to go about this so any advice would be very helpfull.

Unless you plan on really pushing it a lot, you should be fine..

Sonys amps tend to be a little in the weak area though. I have an older STR-DA50ES which used to be number 2 from the top, receiver wise, and my front speakers are also quite large and quite hungry - I added a seperate Poweramp (NAD 2200PE) to get the fronts moving.. Truth said, my Fronts ARE in the silly league with power requirements, they drop down to 3.2 Ohms way down where it's really tough on the amp..

I'd give it a go - Most amps these days will shut themselves off before they die...


[Edit:] Though I already answered - Most Sonys has Pre-Outs for all channels - Adding a sep. P.Amp for the fronts would require nothing but a set of RCA cables and a P.Amp - I highly recommend an old NAD ;-)

 

[Solid Lifters]

One of my roomies recently wanted to hook up a 6.1 or 7.1 system for the tv downstairs, now she got a sony 6.1 reciever (pretty cheap) but the build quality seems decent. Now it is rated at 100 watts per channel at 8 ohms, it doesnt seem to have listed a minimum impedance, nor does it have any type of impedance selector on tha back (which I have heard are usless anyways)
only problem is that it seems the speakers she got are all 4 ohms and the fronts are quite large and require alot of power. will this reciver be ok? and is there any possible way of adding an amp to the reciver?
I'm not sure of the best way to go about this so any advice would be very helpfull.

Don't worry, the amp is 4ohm stable.

However, remember, ohm is a resistance rating, and the lower the number, the less resistance. Less resistance means more power will be delivered than normal. So, 100 watts of amp power will be 140 or 160 watts. That's continuous power, not peak. Peak, depending on the dynamic ability of the amp, will be higher than that. Can the 4ohm speaker handle the peak power the amp will provide it? That's what you need to watch out for.

 

[Flerbizky]

Don't worry, the amp is 4ohm stable.

However, remember, ohm is a resistance rating, and the lower the number, the less resistance. Less resistance means more power will be delivered than normal. So, 100 watts of amp power will be 140 or 160 watts. That's continuous power, not peak. Peak, depending on the dynamic ability of the amp, will be higher than that. Can the 4ohm speaker handle the peak power the amp will provide it? That's what you need to watch out for.

You still need to watch out for the amp as well as the Power Supply might not be able to handle the extra current draw...

 

[Powripper]

Unless you plan on really pushing it a lot, you should be fine..

Sonys amps tend to be a little in the weak area though. I have an older STR-DA50ES which used to be number 2 from the top, receiver wise, and my front speakers are also quite large and quite hungry - I added a seperate Poweramp (NAD 2200PE) to get the fronts moving.. Truth said, my Fronts ARE in the silly league with power requirements, they drop down to 3.2 Ohms way down where it's really tough on the amp..

I'd give it a go - Most amps these days will shut themselves off before they die...


[Edit:] Though I already answered - Most Sonys has Pre-Outs for all channels - Adding a sep. P.Amp for the fronts would require nothing but a set of RCA cables and a P.Amp - I highly recommend an old NAD ;-)

Thanks for the responce!
yeah, I think a seperate amp might be good, these are pretty big speakers and are brand new from her friend (not sute of the brand cause its missing the front grills)

You still need to watch out for the amp as well as the Power Supply might not be able to handle the extra current draw...

Yeah, would rigging up some sort of fan help? like to keep the amp cool?

Don't worry, the amp is 4ohm stable.

However, remember, ohm is a resistance rating, and the lower the number, the less resistance. Less resistance means more power will be delivered than normal. So, 100 watts of amp power will be 140 or 160 watts. That's continuous power, not peak. Peak, depending on the dynamic ability of the amp, will be higher than that. Can the 4ohm speaker handle the peak power the amp will provide it? That's what you need to watch out for.

Yeah, I figured that, these are pretty big tower speakers, 120 watts rms and somthing like 220 max each. 2x 8" and 1x 1 inch silk dome tweeter. so that should be ok?

 

[Solid Lifters]

Yeah, I figured that, these are pretty big tower speakers, 120 watts rms and somthing like 220 max each. 2x 8" and 1x 1 inch silk dome tweeter. so that should be ok?

120 rms is the continuous power rating, remember in 4ohms. The 220 is the peak watts. Your speakers are just fine. Like I said, all Sony home stereos are 4ohm stable. They've been that way since the early '70s. I have a '71 Sony stereo that's 4ohm stable. No need to worry.

However, using 4ohm speaker might overwork the amplifier a bit. Remember, less ohms = less resistance. Less resistance means more power. More power means the amp is working harder to deliver that extra power. So, keeps those vents clear and clean, and don't use too much volume for both the amp and speakers sake.

 

[Powripper]

120 rms is the continuous power rating, remember in 4ohms. The 220 is the peak watts. Your speakers are just fine. Like I said, all Sony home stereos are 4ohm stable. They've been that way since the early '70s. I have a '71 Sony stereo that's 4ohm stable. No need to worry.

However, using 4ohm speaker might overwork the amplifier a bit. Remember, less ohms = less resistance. Less resistance means more power. More power means the amp is working harder to deliver that extra power. So, keeps those vents clear and clean, and don't use too much volume for both the amp and speakers sake.

Well thanks for the feedback guys, I really appreciate it, now this may be a noobish question but does it mean anything that there are two hookups on the back? and does this change how I can power it?

 

[Solid Lifters]

OK, it looks like they add two sets of speaker posts for bi-amplification, perhaps. I wont know why for certain until you look inside to see what exactly is all hooked up and where. With two 8" speakers, it could be a that situation. Depending on how the two 8" speakers are connected, if to each other with series or parallel wiring, it could change the ohm rating of the speaker. Check to see if there's another ohm rating for the speaker. What kind of speakers are these?

Looks good. Just try it and see. Once you run it, switch the negative (black) speaker cable with the positive (red) speaker post, and the other cable vice versa, to test the phase cancellation. Sometimes, things get screwed up internally and sometimes with 12db crossovers, the most popular kind, speaker builders don't run the tweeter half out of phase like they should, so switching the speaker cables around might improve the sound.

Try connecting the speaker wire to either post, but not at the same time, and see how the speaker sounds. Start off will little power and work your way up. Using both speaker posts at the same time from the same amp channel could drop the ohm impedance to 2ohms, and that's not good for the amp.

EDIT: Looking at the pic, I see there's still metal connected to both speaker posts connecting them together? If so, use the bottom speaker terminals only. If the metal as been severed and are not connected, you'll either need to connect them, or run a separate amplifier for each post. Bi-amplification is a costly adventure and really an unnecessary one, I feel. I'm not into it.

 

[Flerbizky]

Well thanks for the feedback guys, I really appreciate it, now this may be a noobish question but does it mean anything that there are two hookups on the back? and does this change how I can power it?

That's for bi-wiring or Bi-amping - 100% sure...

You can wither choose to use one amp and wire to sets of cables, one set for the tweeter and one set for the amp. This can be done from the same speaker output on the amp.. According to "people in the know", this supposedly clears up the top since the cable transporting the signal doesn't get influenced by the heavier pulses of the bass signal.. That's Bi-wiring..

Bi-Amping - Here you can eg. use a smaller better sounding Class A for the top which requires less Oomph and a bigger Class D (or T or whatever) for the lower part which requires aforementioned Oomph.. - This is, of course, a much more expensive solution, but makes more sense to me...

In both cases : Remember to remove the brass connections between the terminals if you try it.

Hope that clears it a little...