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Looking for help ensuring speakers are these suitable for these amps.
This thread has 18 replies. Displaying posts 1 through 15.
Post 1 made on Sunday January 17, 2021 at 16:24
james_aa
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Background :

I want to ensure the technical specs of a speaker, distributed audio amp and AVR are all suitable for each other.

We are looking at using the new Sonance IS8 Invisable speakers.

Sonance IS8 : [Link: sonance.com] (please note there are a few speakers on that page so please only refer to the IS8 column)

The distributed audio zones will be powered by a Savant SIPA125 amp : [Link: store.savant.com]

A 5.1 surround sound zone (a dual purpose living / TV area) is proposed to a Denon AVR X2700 with the same speakers. (the sub will be a dedicated sub and sub amp) : [Link: denon.com]

The speakers state :

Power Handling (RMS) 160W @ 6 ohms

The Savant Amp states :

125WPC at 8 Ohm (although ive been told the Savant amp is a digital amp so there’s no power change when using a 6-ohm speaker. 4, 6 or 8 Ohms will still be 125W)

The Denon AVR states :

Power Output (6 ohm, 1 kHz, 1% 1ch Drive) - 150 W
 
Power Output (6 ohm, 1 kHz, 0.7% 2ch Drive) - 125 W


Question : 

- Are the above amplifiers a good fit to use these IS8 speakers ?

- Is 14 AWG speaker cable suitable to run between these amps and the IS8 speakers. The max cable runs a c. 50 yards.


 
Post 2 made on Monday January 18, 2021 at 08:09
highfigh
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On January 17, 2021 at 16:24, james_aa said...
Power Handling (RMS) 160W @ 6 ohms

The Savant Amp states :

125WPC at 8 Ohm (although ive been told the Savant amp is a digital amp so there’s no power change when using a 6-ohm speaker. 4, 6 or 8 Ohms will still be 125W)

Uh, wut? There are very few ways the output will remain constant with varying impedance and the fact that 'it's a digital amp' isn't inherently one of them. One way is by using output transformers (like a tube amp or a McIntosh) and I really can't think of any others.

The Denon AVR states :

Power Output (6 ohm, 1 kHz, 1% 1ch Drive) - 150 W
 
Power Output (6 ohm, 1 kHz, 0.7% 2ch Drive) - 125 W

Question : 

- Are the above amplifiers a good fit to use these IS8 speakers ?

- Is 14 AWG speaker cable suitable to run between these amps and the IS8 speakers. The max cable runs a c. 50 yards.


 

If you're going 50 yards to some of the speakers, you should be using a 70V amplifier. Screw stereo, send the full signal and make it reliable.

The output power @6 Ohms is immaterial when the speakers are so far away. Your problem will be with nearby lightning strikes, critters chewing the wires and water intrusion.
My mechanic told me, "I couldn't repair your brakes, so I made your horn louder."
Post 3 made on Monday January 18, 2021 at 08:35
iimig
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My professional opinion is that this type of matchup would work, and meet most people’s expectations. However SPL is going to be limited. The efficiency of these speakers is really low at 84db 1w/1m. This is about as inefficient as a speaker comes.

The number one concern with a system like this would be preventing the user from operating the system near maximum levels. Anytime I see a speaker with more power handling than the amps, I get concerned because the opportunity for distortion exists. When the amplifier is outputting maximum current (which may not be enough to satisfy the user based on the low efficiency of the speaker) the wave form can start to distort and go square. When this happens, it damages the voice coil of the speaker. It’s actually safer to have more power at the amp than less. In fact Harman group put out a white paper a while ago that recommended 2x the power handling for most applications and 4x the speaker power handling for amplifier power in a high performance application. Residential systems rarely meet this recommendation but it’s a good design consideration.

Would I do what you are proposing? Yes if the client is looking for a background music quality system. But if it is to be high performance I would be re-thinking it.
The less I say, the smarter I will appear
Post 4 made on Monday January 18, 2021 at 08:50
buzz
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50 yards of #14 is about 0.8 Ohms. To some extent this will protect the amplifier -- and absorb some of your power.
Post 5 made on Monday January 18, 2021 at 13:32
Brad Humphrey
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On January 18, 2021 at 08:09, highfigh said...
Uh, wut? There are very few ways the output will remain constant with varying impedance and the fact that 'it's a digital amp' isn't inherently one of them. One way is by using output transformers (like a tube amp or a McIntosh) and I really can't think of any others.

???
Do you not understand how a digital amp works? The power supply is usually some form of PWM (Pulse Width Modulation) and so to is the output. It varies the power output based on the length of the 'on' times vs. the 'off' times in the modulation.

So running an 8ohm speaker, you can get say 100 watts by the 'on' time being at 100% duty on the modulation. And running a 2ohm speaker, you also get 100 watts because it is running at 25% duty on the modulation.
It is how it limits the power output to operate within safe parameters.

The above is overly simplified but should get the picture.
Post 6 made on Monday January 18, 2021 at 13:56
highfigh
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On January 18, 2021 at 13:32, Brad Humphrey said...
???
Do you not understand how a digital amp works? The power supply is usually some form of PWM (Pulse Width Modulation) and so to is the output. It varies the power output based on the length of the 'on' times vs. the 'off' times in the modulation.

So running an 8ohm speaker, you can get say 100 watts by the 'on' time being at 100% duty on the modulation. And running a 2ohm speaker, you also get 100 watts because it is running at 25% duty on the modulation.
It is how it limits the power output to operate within safe parameters.

The above is overly simplified but should get the picture.

But you even mentioned 'safe parameters' and it's important for the manufacturers to avoid telling users that any impedance is fine. The output section still has limits, so if the amp starts to struggle, power will be reduced.

I wasn't thinking in terms of hitting the lowest power output and using PWM- I was looking at it more like we do with other amplifiers, where the power should increase as the impedance drops.
My mechanic told me, "I couldn't repair your brakes, so I made your horn louder."
Post 7 made on Monday January 18, 2021 at 18:32
buzz
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Analog or digital, a power amplifier is a constant voltage device. Output current rises as load impedance lowers — up to the current limit of the output stage. If the output voltage varied with speaker impedance the output would be horribly distorted because speaker impedance varies with frequency.
Post 8 made on Tuesday January 19, 2021 at 07:37
highfigh
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On January 18, 2021 at 18:32, buzz said...
Analog or digital, a power amplifier is a constant voltage device. Output current rises as load impedance lowers — up to the current limit of the output stage. If the output voltage varied with speaker impedance the output would be horribly distorted because speaker impedance varies with frequency.

I wrote about 'output power', not voltage.
My mechanic told me, "I couldn't repair your brakes, so I made your horn louder."
Post 9 made on Tuesday January 19, 2021 at 09:02
Fred Harding
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What does the manufacturer say?
On the West Coast of Wisconsin
Post 10 made on Tuesday January 19, 2021 at 12:18
buzz
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[Link: savantapac.com]

Maybe I missed something here. I did not see any mention of an audio limiter or compressor function.

There is a statement: "NOTE: Compatible with 8 ohm or 4 ohm speakers."
Post 11 made on Tuesday January 19, 2021 at 12:58
buzz
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On January 19, 2021 at 07:37, highfigh said...
I wrote about 'output power', not voltage.

An audio amplifier is a voltage gain device. The output voltage is a multiple of the input voltage, regardless of input frequency. Power 'P' delivered to the load is P=V˛/R where 'V' is the instantaneous amplifier output voltage and 'R' is the magnitude of the speaker impedance (which varies with frequency). A Volume control sets the gain of the system.

Regardless of speaker impedance the amplifier output stage is rated at a certain current.

Over the operating range of the amplifier all input frequencies at a given level will result in the same output voltage from the amplifier (commonly called "flat" response). The output current at a given frequency depends on the magnitude of the speaker impedance at that frequency. For a typical dynamic loudspeaker system the magnitude of impedance varies wildly by frequency.

---

I'm not sure if I like this analogy, but here goes:

The accelerator of a motor vehicle adjusts power delivered to the wheels. One would use a different setting on level, up hill, or down hill roads in order to maintain a constant speed.

In our audio power amplifier, delivering 100W to a bass driver would probably be satisfying, depending on efficiency and acoustics. In most situations, delivering 100W into a tweeter driver at high frequencies would result in tweeter destruction and potential glass shattering.
Post 12 made on Wednesday January 20, 2021 at 10:26
highfigh
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On January 19, 2021 at 12:58, buzz said...
An audio amplifier is a voltage gain device. The output voltage is a multiple of the input voltage, regardless of input frequency. Power 'P' delivered to the load is P=V˛/R where 'V' is the instantaneous amplifier output voltage and 'R' is the magnitude of the speaker impedance (which varies with frequency). A Volume control sets the gain of the system.

Regardless of speaker impedance the amplifier output stage is rated at a certain current.

Over the operating range of the amplifier all input frequencies at a given level will result in the same output voltage from the amplifier (commonly called "flat" response). The output current at a given frequency depends on the magnitude of the speaker impedance at that frequency. For a typical dynamic loudspeaker system the magnitude of impedance varies wildly by frequency.

---

I'm not sure if I like this analogy, but here goes:

The accelerator of a motor vehicle adjusts power delivered to the wheels. One would use a different setting on level, up hill, or down hill roads in order to maintain a constant speed.

In our audio power amplifier, delivering 100W to a bass driver would probably be satisfying, depending on efficiency and acoustics. In most situations, delivering 100W into a tweeter driver at high frequencies would result in tweeter destruction and potential glass shattering.

Thanks for man-splaining. Really.

WRT 100W into a tweeter, you forgot to mention all of the dogs that would be yelping, in misery.
My mechanic told me, "I couldn't repair your brakes, so I made your horn louder."
Post 13 made on Wednesday January 20, 2021 at 12:43
tomciara
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On January 19, 2021 at 09:02, Fred Harding said...
What does the manufacturer say?

He was de-platformed like so many.
There is no truth anymore. Only assertions. The internet world has no interest in truth, only vindication for preconceived assumptions.
Post 14 made on Wednesday January 20, 2021 at 15:51
Archibald "Harry" Tuttle
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Call Ken at Sonance tech support and tell him your idea and see what he says, he will steer you in the right direction.

We did the legacy IS4 Invisible series for a surround room last year and used a Sonance DSP 8-130 amp for power.

Looks like those IS8s have different guts than the IS4 models.

Call Ken!
I came into this game for the action, the excitement. Go anywhere, travel light, get in, get out, wherever there's AV trouble, a man alone.
Post 15 made on Wednesday January 20, 2021 at 21:51
Ernie Gilman
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On January 19, 2021 at 12:58, buzz said...
An audio amplifier is a voltage gain device. The output voltage is a multiple of the input voltage, regardless of input frequency UNLESS THE LOAD DRAWS SO MUCH CURRENT THAT THE AMPLIFIER'S VOLTAGE DROP UNDER SUCH MOMENTARY OVERLOADS. Power 'P' delivered to the load is P=V˛/R where 'V' is the instantaneous amplifier output voltage and 'R' is the magnitude of the speaker impedance (which varies with frequency). A Volume control sets the gain of the system. THIS IS TOO ESOTERIC TO CONSIDER, BUT IT'S TRUE: ACTUALLY, ANY SUCH SYSTEM IS COMPOSED OF GAIN BLOCKS OF FIXED GAIN, AND THE VOLUME CONTROL(S) ATTENUATE(S) THE OUTPUT(S) OF INDIVIDUAL SECTIONS.

Regardless of speaker impedance the amplifier output stage is rated at a certain MAXIMUM current.

Over the operating range of the amplifier all input frequencies at a given level will result in the same output voltage from the amplifier (commonly called "flat" response) UP TO THE POINT OF OVERLOAD. The output current at a given frequency depends on the magnitude of the speaker impedance at that frequency AND THE AMPLIFIER'S ABILITY TO SUPPLY THE CURRENT DEMANDED BY THE LOAD. For a typical dynamic loudspeaker system the magnitude of impedance varies wildly by frequency.


I'm not sure if I like this analogy, but here goes:

The accelerator of a motor vehicle adjusts power delivered to the wheels. One would use a different setting on level, up hill, or down hill roads in order to maintain a constant speed.

okay....
In our audio power amplifier, delivering 100W to a bass driver would probably be satisfying, depending on efficiency and acoustics. In most situations, delivering 100W into a tweeter driver at high frequencies would result in tweeter destruction and potential glass shattering.

Well, yeah, but it's normal that the amount of power sound decreases by about 6 dB per octave. (That could be way wrong, but the idea holds.) Since it's normal for sounds to have lower power levels at high frequencies, if you feed the same power level to a tweeter, yeah, you'll have big problems.
So...
A flat amplifier would deliver much less power to a tweeter than to a woofer because there's much less high frequency power than bass in an audio signal.

Now I'm wondering what point you're trying to make....
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
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