Amplifiers and "difficult" speakers

K

kosmik

Audiophyte
#1
When amplifiers are being discussed, quite common their ability to drive low-impedance or difficult speakers pops up.
Is there a way to tell that a given amplifier or AVR can or cannot drive given speakers "properly"?

Take my example: I have Focal Aria 948 on front, Focal Aria 900 CC center, Focal Chorus 706 as surrounds, no sub. I use AVR NAD 758 v3. I listen to music at around -30...-15 db depending on recording, movies and games are about -25...-20 db.

Aria 948 impedance drops to less than 3 ohms and in reviews it's considered to be a "difficult load" for amplifiers.

But can I tell somehow if my NAD is totally fine OR I need to add e.g. external power amplifier for fronts? Especially since I don't use sub.
 
K

kosmik

Audiophyte
#3
Yes, it's not powerful. But how to tell if it's enough or not? My speakers are quite sensitive, and from viewpoint of power it seems ok: -20db means that output power is couple of watts, right?

But my main concern is this "difficult to drive" thing which I can't parse from e.g. S&V charts.
 
lovinthehd

lovinthehd

Audioholic Overlord
Ratings
4,328 17 37
#4
Yes, it's not powerful. But how to tell if it's enough or not? My speakers are quite sensitive, and from viewpoint of power it seems ok: -20db means that output power is couple of watts, right?

But my main concern is this "difficult to drive" thing which I can't parse from e.g. S&V charts.
I added to my other post without seeing yours. Do you hear anything amiss? That's a great indicator. Sensitive speakers help, as would not being very far from your speakers. You can play with an spl calculator like this to get an idea of what you're using.
 
K

kosmik

Audiophyte
#6
I don't think I go higher than 80db SPL at my listning position when listening to music. But it's difficult to say if something is amiss: I don't think there was a difference from my old Onkyo TX818 AVR (I replaced just for Dirac).
 
BoredSysAdmin

BoredSysAdmin

Audioholic Overlord
Ratings
5,496 20 33
#7
In car terms: Onkyo TX818 would be like a pickup truck and your current NAD is like a luxury roadster.
Now, if you need to move one person from point to point b with speed limit of 30mph, which car would get there first? You understand my analogy?
Now if you ever need to really blast these speakers crazy loud, but I'd expect 818 would be louder, but honestly with about 80dbl ( or 30mph in my example ),your using only a tiny bit of power anyhow.
 
K

kosmik

Audiophyte
#8
BoredSysAdmin,

So, basically, what you're saying is that if AVR/amp is asked to produce just a few watts of power, then the impedance/phase curve of loudspeaker doesn't matter, so ANY AVR will sound exactly the same in my setup?
 
L

Leemix

Audioholic
Ratings
33
#9
If you have the opportunity to try a good external amp out you really should, to hear for yourself.


Sent from my iPad using Tapatalk
 
K

kosmik

Audiophyte
#10
If you have the opportunity to try a good external amp out you really should, to hear for yourself.
What is considered to be a "good external amp"? Say, a power amp from NAD, NAD 275BEE, is it good? Or it has to be at least Parasound A21 as I've been recommented once?
 
L

Leemix

Audioholic
Ratings
33
#11
What is considered to be a "good external amp"? Say, a power amp from NAD, NAD 275BEE, is it good? Or it has to be at least Parasound A21 as I've been recommented once?
I dont know how the nad 275bee is so cant really say but the parasound a21 would be good to try, i have the a31 and im very happy with it.


Sent from my iPad using Tapatalk
 
BoredSysAdmin

BoredSysAdmin

Audioholic Overlord
Ratings
5,496 20 33
#12
BoredSysAdmin,

So, basically, what you're saying is that if AVR/amp is asked to produce just a few watts of power, then the impedance/phase curve of loudspeaker doesn't matter, so ANY AVR will sound exactly the same in my setup?
Basically yes. You speakers will determine over 95% of sound quality, not electronics. All correctly designed amps, working within their limits (especially below) would sound the same
Not going to deny - some difficult speakers then expected to play at loud levels DO need a more powerful amp and keep in mind these power demands are exponential by physics; You would need approx 6x the power to play 2x louder.
 
P

PENG

Audioholic Overlord
Ratings
4,727 7 1
#13
BoredSysAdmin,

So, basically, what you're saying is that if AVR/amp is asked to produce just a few watts of power, then the impedance/phase curve of loudspeaker doesn't matter, so ANY AVR will sound exactly the same in my setup?
Depends on how you define "a few". A lot of people listen to 75 dB average, 95 to 100 dB peak sitting no further than 8-9 ft, that would translate to an amp driving 8 ohm speakers with around 90 dB spl/2.83V/1M cruising at or below 1 watt average, 115-130 watts peak, no external amp needed in those cases. In your case, 80 dB average is quite high.

Have you tried the calculator @lovinthehd linked in post#4? That really is a prerequisite for this kind of questions.

Regardless, the 948 sensitivity is 92.5 so you should enter 88, or (89 at the most) into that calculator in order to allow for the expected lower impedance. Assuming you sit further than 10 ft, if you do listen to 80 dB spl average then I think external amp(s) will help for sure.
 
lovinthehd

lovinthehd

Audioholic Overlord
Ratings
4,328 17 37
#14
What is considered to be a "good external amp"? Say, a power amp from NAD, NAD 275BEE, is it good? Or it has to be at least Parasound A21 as I've been recommented once?
There are plenty of good amps aside from those brands. Keep in mind it takes a doubling of power to gain a mere 3dB spl advantage. For the prices of those amps you could have a multich amp for all your speakers, something like the Monolith 5 for example.
 
mtrycrafts

mtrycrafts

Audioholic Slumlord
Ratings
1,881 5 3
#15
...

Aria 948 impedance drops to less than 3 ohms and in reviews it's considered to be a "difficult load" for amplifiers.....
Then my question would be what frequency or band where it hits 3 Ohms. I would think above 1 kHz, the power requirement for the same spl is much lower than say 200 Hz and lower. So you do not need much power to drive at 3 Ohms. Unless, the speaker has a crazy phase curve.
 
BoredSysAdmin

BoredSysAdmin

Audioholic Overlord
Ratings
5,496 20 33
#16
Then my question would be what frequency or band where it hits 3 Ohms. I would think above 1 kHz, the power requirement for the same spl is much lower than say 200 Hz and lower. So you do not need much power to drive at 3 Ohms. Unless, the speaker has a crazy phase curve.


NAD 758 v3 isn't really rated for 4 ohm FTC measurements, but it is rated for 4 ohm IHF dynamic power at 243W. So I think OP is just fine with existing avr.
https://nadelectronics.com/wp-content/uploads/2017/06/NAD-T758-V3-Data-Sheet.pdf
 
Last edited:
mtrycrafts

mtrycrafts

Audioholic Slumlord
Ratings
1,881 5 3
#17
It depend if you listen music and films in stereo or the crap they call 5.1 ( home theater ). If you listen only in stereo than a pair of edifier s2000pro is top rated, and the speakers have an included amplifier and all the needed inputs. I only listen everything in stereo and everything is fine and everyone I know had problems when they tried to install and listen 5.1 home cinema systems . Even in real big cinema theater, everything is in STEREO only, but they lied since the seventees with lies like , 3d, surround, Quadrophenia, etc. It is just that sometime they start for a while a speaker somewhere with a special effect, usually vibrating bass bursts. They cannot implement any of these ' standard' because it don't work . In films studio, everything is mixed with one image and 2 channels sound. They should stop trying to kill the market with ' surround ' and instead produce and record nice music and films in stereo with the old 16 bits sound. Sound technicians are now unable to process audio files because each and all digital sound recorders works with incompatible standards. Also since 1980, they introduced computers in music production and only a small proportion of musicians succeeded in creating some interesting songs like gary numan and nine inch nails.
Why don't you tell us how you really feel about 5.1;)
 
B

Beave

Full Audioholic
Ratings
189 1
#18
The "power cube" measurements shown in amplifier reviews in The Audio Critic are a good example of what such a measurement would look like, ie, measuring when an amp clips into different impedances (capacitive, inductive, and purely resistive).
 
B

Beave

Full Audioholic
Ratings
189 1
#19
It depend if you listen music and films in stereo or the crap they call 5.1 ( home theater ). If you listen only in stereo than a pair of edifier s2000pro is top rated, and the speakers have an included amplifier and all the needed inputs. I only listen everything in stereo and everything is fine and everyone I know had problems when they tried to install and listen 5.1 home cinema systems . Even in real big cinema theater, everything is in STEREO only, but they lied since the seventees with lies like , 3d, surround, Quadrophenia, etc. It is just that sometime they start for a while a speaker somewhere with a special effect, usually vibrating bass bursts. They cannot implement any of these ' standard' because it don't work . In films studio, everything is mixed with one image and 2 channels sound. They should stop trying to kill the market with ' surround ' and instead produce and record nice music and films in stereo with the old 16 bits sound. Sound technicians are now unable to process audio files because each and all digital sound recorders works with incompatible standards. Also since 1980, they introduced computers in music production and only a small proportion of musicians succeeded in creating some interesting songs like gary numan and nine inch nails.
lol wut?
 
K

kosmik

Audiophyte
#20
Yes, PowerCube measurements (and The Audio Critic) makes total sense. But since few amps are actually reviewed from this perspective, what should be the strategy: take recording dynamic range and try to extrapolate measurements of amp you have, buy a THX-certified amp (because at least they require ability to do 105db SPL) or just go with Parasouns A21?
 

newsletter
  • RBHsound.com
  • BlueJeansCable.com
  • SVS Sound Subwoofers
  • Experience the Martin Logan Montis