Meaning of 90W + 90W

[Hyperian]

I'm researching on what receiver I should buy for a set of JBL loft i'm getting.

for example, For this sony receiver, it says
6ohms, 20-20kHz, 2ch driven:90 W + 90 W / (0.09%)

Why does it say that instead of just 180W? i'm guessing it means it has less than 180W?

Also, If it says 4ohm/8ohm switching. is it the same thing as a receiver that supports 4ohm/6ohm/8ohm?

 

[alkemyst]

It has to do with a receiver's power at a rated distortion driving a certain frequency range.

While that receiver can push 145W for a single channel (that receiver has 7 of them), if all channels are driven together you will not really see 145W x 7.

The 90W + 90W is a rating for the full frequency range (20Hz-20KHz) with only 0.09% THD, this value is given because historically typically people will listen to music in stereo. Today many are listening to 3 or 5 channel stereo (plus subs).

AFAIK, the 4/8ohm switching is just the range it can handle. At a 4ohm load you may see more power for the same freq range/THD and at an 8ohm load you may see less than what the 6ohm ratings show.

 

[gus6464]

Also note that if a receiver has a 4/8 ohm switch more than likely it will only handle the fronts in 4ohm. The rest of the speakers will have to be 8 ohm or higher.

 

[Hyperian]

Interesting info.

I checked the speakers that I have, and the max watt input to the floor standing speakers is 250watts, while the rear ones are 125watts.

Do I have to drive them at 250 and 125watts to get the best sound experience?

I am having a problem finding any receivers that goes that high (maybe i haven't been searching for the very expensive ones) but i am seeing 80Watts to 100watts, rarely 110. (i am looking at machines from $200 to $500).

Am I missing something?

 

[exar333]

Interesting info.

I checked the speakers that I have, and the max watt input to the floor standing speakers is 250watts, while the rear ones are 125watts.

Do I have to drive them at 250 and 125watts to get the best sound experience?

I am having a problem finding any receivers that goes that high (maybe i haven't been searching for the very expensive ones) but i am seeing 80Watts to 100watts, rarely 110. (i am looking at machines from $200 to $500).

Am I missing something?

You don't need the max power to drive the speaker. I looked-up your JBLs and they are pretty efficienct speakers (91db sensitivity). If you go here, you can calculate how 'loud' the sound will be from speakers by plugging-in your efficiency (91db), power (90W), speakers (2) and listening distance. At 3M, you are at about 104bd, which is VERY loud. http://www.sengpielaudio.com/calculator-efficiency.htm

Really, more CLEAN amp power will ensure the sound stays clear and distortion-free up to a very loud volume. You only need a lot of watts if you have a very inefficient speaker (which you don't have).

Also, keep in mind that the rated power will not be what you can get real-world from this receiver. Unless you are getting a very expensive receiver, you can usually expect about 1/2 or 2/3 of the rated power when running all channels. The two channels at 90w should be relatively accurate, assuming you are running only those two channels.

Lastly, if you really want to have a lot of power go to your fronts, you need a dedicated amp. If your receiver has 'pre-out' connections, you would connect those via RCA or XLR (balanced) directly to a powered amp. The amp would then connect to the speaker. Otherwise, finding a receiver that outputs more than 150w to any channel is pretty rare, and it's usually more cost-effective to use amps vs. a VERY high powered receiver. You can mix and match too. Say you want your fronts to be max powered, and leave the surrounds to power from the receiver. You need a receiver with this inputs/outputs though.

Hope that helps.

 

[alkemyst]

Most speakers rated at X watts peak would die if they even got a clean signal that high.

 

[exar333]

Most speakers rated at X watts peak would die if they even got a clean signal that high.

Very true.

I would also add that surround speakers rarely get used as much as the fronts (music, etc) so they generally use FAR less watts, even with the sound blaring.

Generally, if you have mixed music/movieHT use, I suggest the following:

-Left/Right (provide the most, cleanest power; amp is helpful here)
-Center (don't skimp on the center; voice-match with L/R if possible)
-Surrounds (receiver will generally provide plenty of power for these)

 

[alkemyst]

Very true.

I would also add that surround speakers rarely get used as much as the fronts (music, etc) so they generally use FAR less watts, even with the sound blaring.

Generally, if you have mixed music/movieHT use, I suggest the following:

-Left/Right (provide the most, cleanest power; amp is helpful here)
-Center (don't skimp on the center; voice-match with L/R if possible)
-Surrounds (receiver will generally provide plenty of power for these)

For most people.

Some are driving all the players at full throttle. It needs a big room.

Too many here are putting subs that could bring their whole house down for just a small room and then adding another.

 

[Number1]

This receiver does not support 4 ohm speakers. This "4 Ohm/8 Ohm Switching : Yes (6 ohm)" quote is confusing

http://store.sony.ca/5.2channel-4k-...-All-Receivers-Speakers-and-Stereo-Components

Having owned Sony, Denon and Onkyo receivers I have found that my Denon unit with Audyssey sound calibration sounded best.

 

[Hyperian]

Thanks for all the replies. I am having great fun researching and learning about speaker and receiver setups.

The room I have is around 20 feet by 20 feet that opens into a stairwell and kitchen.

my center is the JBL loft 20.

So i am guessing a 90Watt or 80Watt receiver would be fine for my needs?

What subwoofer spec should look for that matches the speakers I have?

 

[exar333]

Thanks for all the replies. I am having great fun researching and learning about speaker and receiver setups.

The room I have is around 20 feet by 20 feet that opens into a stairwell and kitchen.

my center is the JBL loft 20.

So i am guessing a 90Watt or 80Watt receiver would be fine for my needs?

What subwoofer spec should look for that matches the speakers I have?[/QUOTE]

A good quality 80-90W/ch receiver should be fine unless you plan to really crank-up the volume. I would suggest giving it a try, maxing the volume to what you would expect to use (plus a bit extra) and making sure it sounds good.

For the sub, you can really chose based on what you want/need. There are a lot of good subs in the 200-400w range that are solid, if you really want booming base, then you will probably need to go a bit higher in power.

Check out some of the DIY 'flatpack' subs. You can get amazing bang for the buck on those, and just take a few minutes to put together. It can be pretty fun actually.

 

[Hyperian]

Thanks for all the replies. I am having great fun researching and learning about speaker and receiver setups.

The room I have is around 20 feet by 20 feet that opens into a stairwell and kitchen.

my center is the JBL loft 20.

So i am guessing a 90Watt or 80Watt receiver would be fine for my needs?

What subwoofer spec should look for that matches the speakers I have?[/QUOTE]

A good quality 80-90W/ch receiver should be fine unless you plan to really crank-up the volume. I would suggest giving it a try, maxing the volume to what you would expect to use (plus a bit extra) and making sure it sounds good.

For the sub, you can really chose based on what you want/need. There are a lot of good subs in the 200-400w range that are solid, if you really want booming base, then you will probably need to go a bit higher in power.

Check out some of the DIY 'flatpack' subs. You can get amazing bang for the buck on those, and just take a few minutes to put together. It can be pretty fun actually.

maybe i should just buy this? it looks like for the wattage it is a good deal

 

[exar333]

maybe i should just buy this? it looks like for the wattage it is a good deal

You could definitely do a lot worse than that sub, looks decent. I like to recommend the BIC for a 'great' sub under $200.00.

Amazon has it for ~$180 and comes with a 5-year warranty. Its probably a good step-up from the woot one you linked, and only $50 more.

BIC America F12 12-Inch 475-Watt Front Firing Powered Subwoofer

Edit: The Mirage Omni S8 is also a good option, if you can find on-sale.

 

[Hyperian]

You could definitely do a lot worse than that sub, looks decent. I like to recommend the BIC for a 'great' sub under $200.00.

Amazon has it for ~$180 and comes with a 5-year warranty. Its probably a good step-up from the woot one you linked, and only $50 more.

BIC America F12 12-Inch 475-Watt Front Firing Powered Subwoofer

Edit: The Mirage Omni S8 is also a good option, if you can find on-sale.

Ah, I see, but doesn't the PS SUB 225W have higher RMS wattage than the BIC america F12 with 150Watts?

 

[Hyperian]

came back to post as the result of everyone's help. I kept reading reviews of subs and I end up buying the Dayton sub seeing as it was on sale for $119 after shipping!

 

[gus6464]

Also you are most likely to damage a speaker by under-powering it than over-powering.

 

[Number1]

Also you are most likely to damage a speaker by under-powering it than over-powering.

How so?

 

[gus6464]

How so?

When you have to crank the volume all the way up to get decent output out of a speaker it will eventually cause the amp to clip. The clipping causes a ton of distortion which in turn will burn the speaker. Tweeters are the most sensitive to this in most common crossover networks.

When you overpower a speaker odds are you won't crank the volume high at all to get loud output.

Clipping happens a lot with low impedance, low sensitivity speakers. I have pushed as much as 500W to a speaker that was supposedly only rated for 100W max and nothing happened. I used to own a pair of Epos ELS-3 speakers and those suckers were power hungry. They were tiny but they sure as hell made amps work hard. They became a totally different beast when you gave them a ton of power.

 

[Hyperian]

I'll try to buy a receiver that matches the speakers i have. I am thinking something like the Sony STR-DH540.

 

[sm625]

I am having a problem finding any receivers that goes that high (maybe i haven't been searching for the very expensive ones) but i am seeing 80Watts to 100watts, rarely 110. (i am looking at machines from $200 to $500).

Am I missing something?

If you want to go beyond about 100 watts then you need a completely different circuit design. It will require a lot of additional expensive components. And the efficiency of the higher power circuit will be less than the efficiency of a circuit designed for 10-100W. So you will end up also wasting a lot more energy when listening at "normal" power levels in the 20-40 watt range.

 

[Howard]

When you have to crank the volume all the way up to get decent output out of a speaker it will eventually cause the amp to clip. The clipping causes a ton of distortion which in turn will burn the speaker. Tweeters are the most sensitive to this in most common crossover networks.

When you overpower a speaker odds are you won't crank the volume high at all to get loud output.

Clipping happens a lot with low impedance, low sensitivity speakers. I have pushed as much as 500W to a speaker that was supposedly only rated for 100W max and nothing happened. I used to own a pair of Epos ELS-3 speakers and those suckers were power hungry. They were tiny but they sure as hell made amps work hard. They became a totally different beast when you gave them a ton of power.

http://sound.westhost.com/tweeters.htm