May 12, 2021
Dear folks: I bought a Yamaha receiver RX-V685 with a pair of Niles OS 7.3 outdoor speakers. The speakers burnt out (may be they have less output power than the receiver???), and the seller is suggesting I "upgrade" to a pair of paradigm stylus 470 (with additional money). Does anybody know what should be the speakers requirements for the Yamaha receiver?

I found in the net that the Niles OS 7.3 has a
8 (Ohms)
Power Handling
100 (Watts)
The paradigm specs requires:

15 - 110 watts
80 watts

The Yamaha receiver has these specs:

Rated Output Power (1kHz, 2ch driven)
105 W (8 ohms, 0.9% THD)
Rated Output Power (20Hz-20kHz, 2ch driven)
90 W (8 ohms, 0.06% THD)
Maximum Effective Output Power (1kHz, 1ch driven) (JEITA)
150 W (8 ohms, 10% THD)
Dynamic Power / Ch (Front L/R, 8/6/4/2 ohms)
125 / 165 / 190 / 235 W

What specs should I request for outdoors speakers´ that should be able to handle the receiver output power?

Many thanks.

Art Welter

Jan 11, 2011
A 4-8 ohm speaker conservatively rated for around 100-200 watts should be able "to handle the receiver output power", if you don't clip the crap out of it. Severe clipping (distortion) can double the average power output, burning voice coils. That said, looking at power handling alone is like looking at the fuel tank of a car- it does not tell you how far or fast it can go.

Speaker sensitivity can vary from around 80dB SPL one watt one meter to over 100 dB 1w 1m.
The (larger) 100dB sensitive speaker could put out as much sound level with just one watt as the 80dB sensitive speaker would using 100 watts. The 80dB sensitive speaker would "max out" at only 100dB, while the 100dB speaker could produce 120dB, sounding about four times as loud, or sounding as loud at 10 meters distant as the 80dB speaker sounds at just one meter.

This will give you more information:

Good luck!
May 12, 2021
Can you give me an advice with this? The speakers are in a 200 sqm garden. I have been offered by the dealer a new pair of Niels and paradigm as follows:
CROSSOVERTwo 3rd-order electro-acoustic at 2.3 kHz
HIGH FREQUENCY DRIVERTwo 25-mm (1 in) PTD™ domes
MID/BASS FREQUENCY DRIVERDual voice-coil, 190-mm (7-1/2 in) ICP™ cone, die-cast chassis
SENSITIVITY ROOM / ANECHOIC93 dB /90 (dB) For 2.83V pink noise
FREQUENCY RESPONSE 30° OFF-AXIS±2 dB from 75 Hz - 15 kHz65Hz - 21kHz +/-3dB
SUITABLE AMPLIFIER POWER RANGE15 - 110 watts Mono; 15 - 55 watts / channel Stereo Input
MAXIMUM INPUT POWER80 watts Mono; 40 watts / channel Stereo Input
IMPEDANCECompatible with 4 ohms Mono; 8 ohms / channel Stereo Input8 (Ohms)

Art Welter

Jan 11, 2011
To expand on Caleb Dueck's reply to your duplicate thread, neither of the speakers offered to you will be sufficient for "loud" (110dB peak) music at more than a few meters.

An 8 ohm consumer speaker rated for 100 watts (28.3volts into 8 ohms) may be burned with as little as 3.125 watts (5 volts into 8 ohms), as I found with one of my 8 ohm Tannoy PBM 6.5 near field monitors.
The Tannoy PBM 6.5 speakers have similar sensitivity and power specifications to the Niles OS 7.3 speakers you burnt already and the Stylus 470 (even less rated power) that you are considering.

So how can a “100 watt” speaker that I used for over 20 years powered with a 200 watt amplifier be blown by 3 watts?

The difference between peak and average power, and the way speakers and amplifiers are rated provide most of the explanation.

Consumer speakers like the above that don’t specify how the power rating is done may be rated for peak power using a source with similar crest factor as music.

More professional speaker power ratings like the AES2-1984 use average, or RMS (Root Mean Squared) power with a 6dB crest factor for testing. A speaker with a 100 watt nominal AES rating should sustain 400 watt peaks for two hours.

The peak to average power ratio, or crest factor in dB is the difference between the RMS value and the peak amplitude of the signal.

Some heavily compressed music (like Metallica’s “Death Magnetic” album..) may have as little as 6dB crest factor, the same as used to test professional speakers.

A 6 dB crest factor is power ratio of 4. An amplifier producing 100 watt peaks (no clipping) with a 6 dB crest factor would average 25 watts, 100/4 =25.

With a crest factor to 12dB, typical of pink noise or less compressed music, the power ratio is x16, 100/16 = 6.25 watts average.

Dropping to the 15 dB crest factor of “normal” music, a speaker could be rated for 100 (peak) watts while sustaining just 3.125 watts on average.

One side of a Hafler DH-200 amp ([email protected]) driving my Tannoy PBM 6.5 speaker had a little DC voltage on one channel that slowly grew from a small fraction of a volt to 5 volts over the course of 20 years.

5 volts into 8 ohms impedance is 3.125 watts, the “100watt 8ohm” speaker should have handled it, but as the woofer’s DC resistance was near 4 ohms, power delivered was double, 6 watts was enough to cause the voice coil to burn, as the DC held the voice coil in a fixed position, allowing no air cooling as the speaker sat powered, but idle.

Then there is the issue of “power compression”, but you can look that up easily..



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