Driving inefficient speakers (82.5db, 4 Ohms) on AVR.

[flexy123]

I have a Marantz SR5013 and two rather "ineffecient" Nubert speakers 82.5db/1m@ 4Ohms. (nuBoxx B-40)

For the AVR it says in the specs it can drive 185W for 2x speakers at 4Ohms, and of course less the more speakers are connected.

Now, I don't have any issues with this setup currently, yet I learned (and am still learning) a lot recently, and I understand these are inefficient speakers. Could this be a "problem" in the future when I build a 5.1 setup and assuming I would like to drive "crazy volumes" (as the Marantz wouldn't be able to deliver reference levels this way), and using calculators I would need a 800W Monster to drive these speakers at reference. (The good thing is, I will likely never listen that loud).

The other issue might be driving the AVR too hard, heat etc....

NOW: I will get a sub tomorrow and I plan to crossover the mains, 60-80hz. (Will need to see, will likely go with 70hz xo).

Do I understand this right that this means I will be taking most of the load off the AVR and that this would do away with such concerns?
Does this mean that with a sub, the mains can now be driven "louder", as now there will be more power reserves for the mids/highs?

Thanks!!

 

[LoFiAudiophile]

Assuming you’re happy with the speakers and the AVR, you can always add an amplifier downstream of the AVR to drive the speakers. You can choose a stereo or a mono amp per speaker if you want to get fancy. Something like a Fosi V3 can easily drive these speakers and is relatively cheap for state of the art performance.

 

[flexy123]

Yes I am currently good with the Marantz. I had previously heard that these Fosi Amps are allegedly only good for near field, but they must have talked about some other models. This one looks spectacular, in particular for the price!

 

[pogo]

I plan to crossover the mains, 60-80hz

That doesn't really make things any better, see also here: Link
The lowest EPDR values are above the crossover frequencies.
Take a look at the new MA series from JBL.
These low EPDR values are not a problem for class-D stages (see also new JBL AVRs, Fosi, ...).

 

[antcollinet]

Yes I am currently good with the Marantz. I had previously heard that these Fosi Amps are allegedly only good for near field, but they must have talked about some other models. This one looks spectacular, in particular for the price!

Second what @LoFiAudiophile says. Your AVR is fine as long as you can get the volume you need. If at any point you feel you need more oomph, or want to take load off the AVR, then you have a good set of pre-outs which not all AVRs posess. Connect 2 or more Fosi V3 Monos to these, and you will be golden.

On the other. hand, bear in mind 3dB is a doubling in power. If your speakers are genuinely only 82.5dB, then going to speakers with 85.5dB will be the same as doubling the power of the amp. Speakers with 89dB sensitivity would be the same as 4 times the power.

 

[DVDdoug]

I had previously heard that these Fosi Amps are allegedly only good for near field,

The amp doesn't know anything about near-field or far-field.

assuming I would like to drive "crazy volumes"

More efficient speakers are probably part of the solution. Pro speakers used live and in studios tend to be efficient (especially PA speakers) AND driven with plenty of power.

and using calculators I would need a 800W Monster to drive these speakers at reference.

What's the power rating on your speakers.

 

[LSPhil]

I think you're exaggerating with those 800W.

800W->29 dB+82.5=111.5 dB

Gentlemen, that's really too much

 

[antcollinet]

I think you're exaggerating with those 800W.

800W->29 dB+82.5=111.5 dB

Gentlemen, that's really too much

That is at 1m. And peak power

Make that 3m then allow 15dB for musical dynamics, and you are down at about 85dB

 

[mhardy6647]

On the other. hand, bear in mind 3dB is a doubling in power. If your speakers are genuinely only 82.5dB, then going to speakers with 85.5dB will be the same as doubling the power of the amp. Speakers with 89dB sensitivity would be the same as 4 times the power.

Funny that, eh?
I am deeply baffled (no loudspeaker pun intended) by why any designer feels the need to specify an enclosure alignment, drivers, and XO components that result in loudspeakers of such low sensitivity. The corollary poor electrical efficiency of most low sensitivity loudspeakers seems particularly tone deaf in the current world. (no puns intended by way of tone deaf nor current, either).

 

[LSPhil]

111.5-9.5=102dB Only one Speaker. I better get out of this room. the quietest passage is 87 dB and max 102 dB. I think I'm leaving

 

[antcollinet]

111.5-9.5=102dB Only one Speaker. I better get out of this room. the quietest passage is 87 dB and max 102 dB. I think I'm leaving

Well we could argue about what musical dynamics look like.

For me your transient peaks (eg drum hits during a loud section) are going to be at 102dB. Your loud sections of music are probaby down 10dB from there, and your average SPL for a song is probably down a futher 5 to 10 dB. So average is 82 to 87dB.

That is loud but not outrageous.

 

[flexy123]

What's the power rating on your speakers.

160/220W

(Practically I don't have any issues with levels, I don't even remotely listen at a volume that the AVR/speakers could produce, maybe 30% of it. And this with the speakers being "very inefficient"

 

[LSPhil]

These speakers have low sensitivity primarily because it's technically challenging to achieve deep low-frequency response with high efficiency. To increase volume, it's advisable to incorporate a subwoofer into the system, while ensuring that the satellite speakers are not restricted by a high-pass filter. In enclosed spaces, both the surface area in the bass region and the excursion of the drivers are crucial factors for performance.

 

[pogo]

I don't have any issues with levels

Really? Have you ever heard the B-40s on a potent amplifier?
Which impedance setting did you choose on the Marantz?

 

[LoFiAudiophile]

Really? Have you ever heard the B-40s on a potent amplifier?
Which impedance setting did you choose on the Marantz?

If the amplifier isn’t clipping, the power rating doesn’t matter for any competently designed amplifier. Louder music always sounds “better” subjectively, but it’s just loudness doing the magic. If one doesn’t want to listen louder, it’s a moot point.

Impedance selectors just change the clipping/shutdown point of the amplifier, they don’t change the sound quality in any meaningful way.

 

[pogo]

Impedance selectors just change the clipping/shutdown point of the amplifier

This is not the whole truth. Here a similar case: Link

 

[AwesomeSauce2015]

To address your original post:
If your amp delivers the volume you want, then you are good. Adding a subwoofer crossover will help a little bit in terms of reducing the load on the main speakers, and shifting it to the subwoofer, which will provide a sonic benefit (in theory). However, those are really inefficient speakers, and so I will move on to your question about "Reference Levels"
"Reference Level" in cinemas and large studios will be somewhere around 85db @ -20dbFS. That means, peaks up to 105db at the listening position on the mains, and 115db on the subwoofer channel (the sub is calibrated 10db higher, iirc).
In a typical domestic room, 85db is perceived as much louder than in one of those large studios or cinemas. This is an acoustic effect, so speakers / amps are not the cause or solution. The solution is that in domestic settings, we calibrate 6db lower than the "reference level". This means 99db peaks at the listening position and 79db @ -20dbFS.
This also has the added benefit of reducing our amplifier and speaker needs significantly.

The main issue in your situation is that since your speakers are so inefficient, it is unrealistic to drive them to any of these reference levels. Even if they could handle 800w, the issue with driving normal, domestic speakers with that much power is one of heat and thermal / mechanical compression. Simply put, the tweeter, crossover, and woofer can't handle that much power, and probably can't handle much over 200w either. This is why the home theater crowd likes horn speakers, and other more efficient speaker designs so much, it's not just that they are easier to drive loud, but that they are designed to be driven loud, and the relevant components can take the power without overheating and degrading the sound.

So: Will those speakers be an issue if you expand to a 5.1 setup? Maybe. It depends on your room, and your listening goals. Personally, I wouldn't build a home theater around these speakers since I design to be able to hit 105db peaks from the main speakers (Big rooms, and friends who like to "show off" their systems). If you expect to ever want to go full "homer simpson", I would look into getting more powerful speakers from someone like JBL's HDI or Studio 6xx line, Klipsch's RP series or RF-7, or the Martin Logan XT series. You could also get an external amplifier, but in my opinion, once you have 100w, you already are capable of pushing pretty much any "home audio" speaker pretty hard, so with those speakers I would say an external amp probably won't help a lot if you need more dynamics.

 

[pogo]

For the AVR it says in the specs it can drive 185W for 2x speakers at 4Ohms

Where did you get that from?
I only see a clean spec at 8ohms.
At 6ohms the spec is only at 1kHz (not full-range!) and with higher distortion.
I can only advise you to listen to the Nubis on an adequate amplifier so that the full potential is revealed.

 

[LoFiAudiophile]

This is not the whole truth. Here a similar case: Link

Quoting from the link:

> With current AV receivers, you can change the impedance of the connected speakers using a key combination described in the operating instructions. If you select 4 ohms here, the amplifier limits the available power to prevent overloads.

This is exactly what the impedence selector does on practically any Amp. Selecting 4Ohm enables current limiters to prevent overload. It doesn’t give you more power or quality, just a slight chance of not overheating the amp when driving it at max power for extended period of time. You don’t have to take my word for it, it’s described in the manual of the Amps.