What does it mean if a speaker is "inefficient"

[Johnny Canuck]

someone told me my Polk RTI 12's are "inefficient". What does it mean?

I bought these things before i started reading these forums unfortunately. paid a pretty penny for them. Constantly trying to get the bass out of them I read about on the Polk website forums. The guys in the forum discribe them as "beasts" and "bad boys"etc....rave about them and say you hardly need a sub with them. Well i have just about thrown all credibility out the window with those posters on that site because today i set the speaker settings on my Denon 3805 to sub "off" and heard very little to no bass whatsoever on these "beasts". Even with a NAD power amp on the lows only.

so is this because they are "inefficient"? more like "insufficient"

if I set the fronts to small, am i wasting my time with a power amp on the lows? Am i still getting power from my amp for low bass or mid bass? How should i be wiring this thing? When i put the jumpers back on and run the NAD full range on fronts, i find them too bright. maybe it's because my room is only 12 x 12 with lots of window and hard wood floors?

man, i feel like I got ripped off.

 

[Privateer]

They reccomend 50-500 w/channel and the Efficiency is at 90dB which is good. What is the power rating on your amp?

 

[Johnny Canuck]

the NAD 2200 is 100W with 6db of headroom so from what I was told, that's equal to 400W approx...wattage doubles for every 3db of headroom...

 

[Buckeyefan 1]

Right, for every 3db, you need twice the power for the same volume. Klipsch speakers are very efficient, usually over 94db. Polks are inneficient at 89db. Electrostats are the worst, and need huge amps to drive them. Inneficiency isn't a bad thing, because better drivers with larger magnets and voice coils always need more power. I'm sure someone can explain it better than that, but that's it in a nutshell.

 

[mtrycrafts]

someone told me my Polk RTI 12's are "inefficient". What does it mean?

I bought these things before i started reading these forums unfortunately. paid a pretty penny for them. Constantly trying to get the bass out of them I read about on the Polk website forums. The guys in the forum discribe them as "beasts" and "bad boys"etc....rave about them and say you hardly need a sub with them. Well i have just about thrown all credibility out the window with those posters on that site because today i set the speaker settings on my Denon 3805 to sub "off" and heard very little to no bass whatsoever on these "beasts". Even with a NAD power amp on the lows only.

so is this because they are "inefficient"? more like "insufficient"

if I set the fronts to small, am i wasting my time with a power amp on the lows? Am i still getting power from my amp for low bass or mid bass? How should i be wiring this thing? When i put the jumpers back on and run the NAD full range on fronts, i find them too bright. maybe it's because my room is only 12 x 12 with lots of window and hard wood floors?

man, i feel like I got ripped off.

Sensitivity relates to the amount of SPL you get at 1 m with 2.83V at the speaker terminals. The louder it is, the less amp power it needs to drive it.

Now, if your Polk is set to small, no wonder you don't get bass from it, the signal cuts off at 80Hz, or so. Try it on large. But even then, it depends on th espeakers ability to go low in frequency and loud.

 

[Johnny Canuck]

No martycrafts..i had my sub turned off so the Denon automatically set the fronts to large.

I wanted to know if I will get any benefit of this amp on my lows if I set the fronts to small? I seem to recall reading an article recently on Audioholics that even if your speakers are big towers, you should ALWAYS set them to small. So in reality, the NAD is useless just on my lows you are saying? Just consuming electricity and looking pretty in my rack????

 

[Buckeyefan 1]

No martycrafts..i had my sub turned off so the Denon automatically set the fronts to large.

I wanted to know if I will get any benefit of this amp on my lows if I set the fronts to small? I seem to recall reading an article recently on Audioholics that even if your speakers are big towers, you should ALWAYS set them to small. So in reality, the NAD is useless just on my lows you are saying? Just consuming electricity and looking pretty in my rack????

JC,

Went down and experimented with my Polks just now. I got pretty awesome bass from them with these settings and only using the 3805. Put in a good cd with punchy, as well as deep bass. Set the receiver to "stereo". Turn the bass to +6 and keep the treble at 0 (or lower since you have a bright room). T Tone should be at "manual" and tone defeat "off". Crossover at 40hz and Sub set to "off" as well as fronts set to "large". That should cancel out the crossover anyhow, but just to be safe. Now set your parametric eq for your front rights at +6 for 63hz, +6 for 125hz, and +3 for 250. You can also adjust the level of the fronts up to +12 since these RTi's take so much to get moving. I have mine set on +5.5. Those little 7" subs should be moving like a bat out of hell now. I was able to turn up the system to -5 without any noticable distortion. Assuming you can still use the Denon as a preamp, use your NAD to power your 7" woofers, not the highs. You ARE wasting your money with these speakers if they are set to "small", especially when playing music. Dialing in a system is one of the most difficult things to do. Are your towers placed in corners? In a 12x12 room, I would think the high's would be so bright, you couldn't turn up the system loud enough to even hear your 7" woofers. You may have to dial down the mids and highs until the bass evens things out. It sounds like you just haven't realized the potential of your towers yet!

 

[Johnny Canuck]

Went down and experimented with my Polks just now. I got pretty awesome bass from them with these settings and only using the 3805. Put in a good cd with punchy, as well as deep bass. Set the receiver to "stereo". Turn the bass to +6 and keep the treble at 0 (or lower since you have a bright room). T Tone should be at "manual" and tone defeat "off". Crossover at 40hz and Sub set to "off" as well as fronts set to "large". That should cancel out the crossover anyhow, but just to be safe. Now set your parametric eq for your front rights at +6 for 63hz, +6 for 125hz, and +3 for 250. You can also adjust the level of the fronts up to +12 since these RTi's take so much to get moving. I have mine set on +5.5. Those little 7" subs should be moving like a bat out of hell now. I was able to turn up the system to -5 without any noticable distortion. Assuming you can still use the Denon as a preamp, use your NAD to power your 7" woofers, not the highs. You ARE wasting your money with these speakers if they are set to "small", especially when playing music. Dialing in a system is one of the most difficult things to do. Are your towers placed in corners? In a 12x12 room, I would think the high's would be so bright, you couldn't turn up the system loud enough to even hear your 7" woofers. You may have to dial down the mids and highs until the bass evens things out. It sounds like you just haven't realized the potential of your towers yet!

 

[Johnny Canuck]

Sorry buckeye...screwed up that last post...i accidently cut and pasted your post!!

I will try that but i have a question or two....

"T Tone to manual" do you mean "room eq"? i usually have that OFF, sounds the best..

I have tried experimenting with the tone. SQ is nowhere as clear with the tone defeat off to me....

you say to have the front Large? i did before with the weak Polk sub, but now with this PSB 6i, (a great sub i haven't taken back yet as my Hsu STF3 will arrive next week) the system sounds better with the fronts on small,


BTW, with the fronts on small, i still feel a little movement on the woofers..

will go play with your recommendations!! Thanks buckeye!!

here is my set up in a 12x 12 room: the left one in the corner, sub next to it to the right, the TV, then the right one on the other side of the TV...6 feet from my listening position. my couch is up against a wall facing the fronts, rear speakers, Polk RTI6's are to my side about 3 feet away from my head...

JC

 

[Buckeyefan 1]

JC,

You are absolutely right...

"T Tone to manual" do you mean "room eq"? i usually have that OFF, sounds the best..

I have tried experimenting with the tone. SQ is nowhere as clear with the tone defeat off to me...."

The sound won't be as good, but I just wanted to show you your towers can produce the bass they were meant to produce. You're towers are a lot better than mine, and I've been very pleased so far even though I'm missing a midrange. I've just compensated with the parametric eq.

There's a thread towards the bottom of the main forum page on peoples' setups (actual photos). You'll have to post yours. I'll get mine on sometime too. Hopefully more of the active guys will post their systems they've taken so long to build up. There's only a few down there now that I've said "wow" to.

 

[Johnny Canuck]

I have spent too much on my home theatre system to afford a digital camera

I have an old pair of Technics speakers with a 12" driver on the front and another in the back, a passive radiator. i had these for 10 years before I bought these Polks. i have gone through 3 receivers/amps over the years, from the first one being a Technics power amp, then graduating to a Pro Logic receiver. these speakers used to shake the house. without a subwoofer. i tried them on the Denon 3805 and they were also weak in the bass. I am wondering if new digital receivers, with all the bass management, 5.1, etc, are lacking in the bass department no matter what speakers you have. It's like you HAVE to use a sub. i may pull them out storage and see what this NAD sounds like on them just for fun. Unfortunately this NAD is just a straight power amp, no controls, no gain..would still have to run it through the receiver..

Thanks..i am going to get to your recommendations later on...

 

[mtrycrafts]

So in reality, the NAD is useless just on my lows you are saying? Just consuming electricity and looking pretty in my rack????

If th espeaker is set to small then the low driver's response would depend on the speaker's crossover frequency, where does it cross to the low frequency driver. Remember though that the crossover has a cut off slope so it will go down below the crossover but at the slope rate, 6dB, 12dB, 18dB slope.

So, it may be doing nothing, yes.

 

[Johnny Canuck]

sorry mtycrafts. That post sounded like Japanese to me.

the internal crossover on my RTI 12's is 120hz I think. is that what you are referring to?

so why do my drivers vibrate a little even when set to small and crossover at 80hz?

however i do notice a big change when I have the fronts set to Large and i switch from "LFE" to "LFE + Main".

maybe when i move to a bigger place I will run the NAD on full range on the fronts...i think the brightness issue is because the room is so small....

I just did a test actually. Went up to my NAD and hit the power button...turned it off, bass considerably went down. Turned it on, bass came back on the fronts. Not a heck of a lot, but some nevertheless. Receiver is on "Small" crossover at 80hz..

 

[Johnny Canuck]

Buckeye...you are the man!!

did what you suggested, and I heard what these Polks can really do!! Not quite as good a sound as a sub, set to small, but yes, the woofers were moving big time and i only had it at -20!! Too loud in my place if I go any louder!! And the SQ is not as good as the Tone defeat ON but at least i heard bass out of those things for the first time!! And they are shaking my place.

Put on Disco Inferno by 50 cent and it sounded great. (No i am not a rap fan but i needed to test deep bass). You just made my day.

Thanks again.

 

[mtrycrafts]

sorry mtycrafts. That post sounded like Japanese to me.

the internal crossover on my RTI 12's is 120hz I think. is that what you are referring to?

so why do my drivers vibrate a little even when set to small and crossover at 80hz?

however i do notice a big change when I have the fronts set to Large and i switch from "LFE" to "LFE + Main".

maybe when i move to a bigger place I will run the NAD on full range on the fronts...i think the brightness issue is because the room is so small....

I just did a test actually. Went up to my NAD and hit the power button...turned it off, bass considerably went down. Turned it on, bass came back on the fronts. Not a heck of a lot, but some nevertheless. Receiver is on "Small" crossover at 80hz..

Yes, the speakers internal crossover at 120 will send those to the low driver down to the point where that "small" speaker setting cuts off the speaker.
However, that is not a brick wall cut off filter at 80Hz, it has a slope as I stated, so you will get some cone movement below that, even if you cannot hear it.

 

[annunaki]

They reccomend 50-500 w/channel and the Efficiency is at 90dB which is good. What is the power rating on your amp?

Mtrycrafts is correct Sensitivity is measured in db/meter.

Efficency is usually not given. Sensitivity is the measure of how well the speaker translates 1 watt (2.83 volts at 8 ohms, 2.45 volts at 6 ohms, 2 volts at 4 ohms) of input power into output power (using all the drivers and enclosure) at 1 meter.
Efficency is how well a speaker (actual driver) can convert electrical energy into mechanical energy. The less amount of electrical energy wasted in heat the more efficent the speaker is. Most speakers (actual drivers not including enclosures ect.) are only about 1-2% efficent (at least from the info I have seen) in doing this.

 

[Francious70]

From what I've seen, speakers usually arn't even 1% efficient.

http://www.adireaudio.com/Files/TechPapers/DualVoiceCoilDrivers.pdf

Scroll to page 3.

Paul

 

[mtrycrafts]

Mtrycrafts is correct Sensitivity is measured in db/meter.

Efficency is usually not given. Sensitivity is the measure of how well the speaker translates 1 watt (2.83 volts at 8 ohms, 2.45 volts at 6 ohms, 2 volts at 4 ohms) of input power into output power (using all the drivers and enclosure) at 1 meter.
Efficency is how well a speaker (actual driver) can convert electrical energy into mechanical energy. The less amount of electrical energy wasted in heat the more efficent the speaker is. Most speakers (actual drivers not including enclosures ect.) are only about 1-2% efficent (at least from the info I have seen) in doing this.

Another issue all should keep in mind. Speaker efficiency, how well it converts electrical power to acoustic power is not very useful to the end user. On the other hand, sensitivity is, which speaker needs more or less power for a given spl.

 

[annunaki]

Quite true Mtrycrafts. I was simply pointing out that the two terms should not be used interchangably.

 

[annunaki]

From what I've seen, speakers usually arn't even 1% efficient.

http://www.adireaudio.com/Files/TechPapers/DualVoiceCoilDrivers.pdf

Scroll to page 3.

Paul

There are some, but yes there are not a lot that exceed 1%.