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If One Speaker is Playing @ 90 dB...
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Blue Shadow
Waiting for Vintage Gear from this century
+3dB for the additional speaker (both playing 90db)
+3dB again for the second pair. (all playing 90dB as the original one speaker)
A doubling of the speakers playing the same volume as the original speaker(s) will add 3dB for the same distance.
Math gets harder at 3 pair, not as much increase.
+3dB again for the second pair. (all playing 90dB as the original one speaker)
A doubling of the speakers playing the same volume as the original speaker(s) will add 3dB for the same distance.
Math gets harder at 3 pair, not as much increase.
Thanks for the quick responses.
I thought it would have been more than just 3 dB - at least it sure sounds like it should be more than that to me: 3 dB change is usually not that easy to hear but if I turn the balance all the way to one side or the other (cutting one speaker out) - that difference in loudness is very noticeable to me.
Anyway it blows a theory I had been working on out of the water...:sigh:
I thought it would have been more than just 3 dB - at least it sure sounds like it should be more than that to me: 3 dB change is usually not that easy to hear but if I turn the balance all the way to one side or the other (cutting one speaker out) - that difference in loudness is very noticeable to me.
Anyway it blows a theory I had been working on out of the water...:sigh:
Assuming the amp is how many watts? And all speakers are being driven by equal power? How far is the distance to the LPos?
Hypothetically:
At 100 watts / 3 meters, two speaker SPL is 103.5 dB
4 matched speakers at the same power & distance gives an SPL of 106.5 dB
6 matched speakers gives 108.27 dB
*Real values may vary and and SPL meter might be useful in calibration.
Here's the scientific reference page I used;
http://www.sengpielaudio.com/calculator-efficiency.htm
The previous values posted (93, 96, 99) are also correct. Assuming the default 1 watt @ 1 meter.
Hypothetically:
At 100 watts / 3 meters, two speaker SPL is 103.5 dB
4 matched speakers at the same power & distance gives an SPL of 106.5 dB
6 matched speakers gives 108.27 dB
*Real values may vary and and SPL meter might be useful in calibration.
Here's the scientific reference page I used;
http://www.sengpielaudio.com/calculator-efficiency.htm
The previous values posted (93, 96, 99) are also correct. Assuming the default 1 watt @ 1 meter.
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SaSi
Seriously Illogical
I'd say that 3dB is pretty much audible in any term. It's about doubling the acoustic output and that's something pretty significant. Something like doubling the amplifier power from 60WRMS to 120WRMS.
I wonder what exactly are you experimenting with and the exact conditions.
Assuming that all 6 loudspeakers you are using are identical (what model?) and since 1-3W is certainly not in the range of compression and loss of linearity, 2W sent to one of these loudspeakers should be equivalent to 1W sent to two of them (each). And 4W sent to one of them should provide similar output with 1W sent to 3 of them (each).
Now, to be able to do this correctly, you need 3 identical power amplifiers, right? If you are feeding the loudspeakers from the same amplifier, then you are sharing the output and hence the estimations will be off.
I wonder what exactly are you experimenting with and the exact conditions.
Assuming that all 6 loudspeakers you are using are identical (what model?) and since 1-3W is certainly not in the range of compression and loss of linearity, 2W sent to one of these loudspeakers should be equivalent to 1W sent to two of them (each). And 4W sent to one of them should provide similar output with 1W sent to 3 of them (each).
Now, to be able to do this correctly, you need 3 identical power amplifiers, right? If you are feeding the loudspeakers from the same amplifier, then you are sharing the output and hence the estimations will be off.
Billy Dio
Well-Known Member
Look at this link: http://www.colomar.com/Shavano/spl.html It has a graph for single speakers, but clearly illustrates how a speaker's SPL is so crucial to how easily it can get "loud". For example, I think this is fairly extreme contrast right here. 1024 watt amp powering an 86 db SPL speaker will be 116 db, whereas a 16 watt amp powering a 104 db SPL speaker will also yield the exact same 116 db. Pretty trippy if you think about it. Although the graph only shows down to 86 db, you can easily see the pattern in the graph to deduce db at say 83 db SPL and so on. This is also explains how some 30-50 wpc smaller amplifiers with a ton of dynamic range can sound just as loud as units with 2-3 times the wattage, as long as the mids, highs are really high SPL (which most are) coupled to a lower RMS wattage but again HIGH SPL woofer can rattle the plates out of the cupboards 4 rooms away.
Also, another thing to consider is I believe most vintage amps series the load if you connect additional speakers via A+B+C switches on unit. So a 60 wpc @ 8ohm will effectively become 30 wpc @ 16 ohm with A+B, then that 30 wpc is evenly distributed between your extra speaker per channel. But following the graph and using the 3db+ for adding it, you realize that extra 30 w isn't really missed. Although I will say the speakers won't be as "full" sounding at the same gain. Obviously, if your amp can do 4 ohm in parallel, yo'll get more wattage plus the 3db, but you'll also get more heat.
EDIT: Made correction with the 116 db
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whoaru99
Epic Member
While it's true about 3dB being a doubling of power, e.g. 60W to 120w, that change isn't much difference in perceived volume. It takes an increase of 10dB to be perceived as ~twice as loud.
But, to your other point, it's a good one. Are the extra speakers receiving all the same power, or is the power divided among all the speakers?
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A bit off topic but related...while I've seen some receivers that put the connections in series when the B terminals are activated, I've not found this to be the norm. And the receivers with which I'm familiar which offer three sets of terminals allow only two sets to be active simultaneously. Of course, there will may be receivers/amps which do allow for three active pairs....I've just not seen one that I can remember.
Billy Dio
Well-Known Member
I think it boils down to whether the amp is actually listed as 4 ohm stable or not as that'll dictate whether the amp is even capable of paralleling the load. Most vintage amps I've come across usually allow for either 4 ohm (or 8 ohm) with only A or B, or 8 ohm A + B, as 4 ohm parallel A + B = 2 ohm loads.
Also, I only listed the A+B in the A, B, C, scenario.
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whoaru99
Epic Member
FWIW, several of the Yamaha M-series have A, B, and C speaker. All can be used simultaneously.
I believe A+B and A+C are parallel, but B+C are series. So, if all three are selected, A is in parallel with series of B & C.
From my M-80 and M-40s, for example, impedance ratings are -
A or B or C: 4 ohms min
A+B or A+C: 8 ohm min
B+C: 2 ohms min
A+B+C: A = 8 ohms min, B & C = 4 ohms min.
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Rob41
Don't stop believin'
Now try that again, only this time set your speakers right up against each other, and stand as far back as you can while someone else rotates the balance knob back and fourth.
In your original test you heard a 3db swing rotating your balance knob, but you also heard a distinct shift in the location of the sound making the overall impression of volume seem greater than it actually was.
That's been my observation too. The only one's I've seen that series the A and B terminals when both are selected are earlier solid state units. When selecting four or eight ohm terminals on earlier units some of the early solid state units would put a four ohm resister is series with the four ohm terminals. Better tube units had different taps on the output transformers for four or eight ohms.
I cannot explain it but the difference in SPL between 1 wpc (x3) into 3 pairs of speakers is totally different than the same 3 wpc into a single pair.
Not only that, bass extension is also far superior than what is to be had by a single pair of speakers - no matter how much the volume is increased.
I realize the math doesn't support any of this but I can't explain it.
Three amplifiers are used in this system and all speakers are 8 ohm. The rear pair are Polk RTiA9 (90 dBw); fronts are Polk RTiA7 (89dBw) and Snell J7 (89dBw). Amps are MC 2125 (x2) fronts; MC 2155 rears. All power meters calibrated.
The Gains of the amplifier for the rears are set so that the sound is balanced to the fronts. In fairness - the gain of the right rear speaker is set higher than the left rear so if the front amps register 1.2 watts, the right rear might be at 1.75 or so; the left rear would be 0.5 watt to compensate of the difference in distance between L & R to listening spot.
Are there any sonic advantages to be had by speakers not "having to work as hard" at a given volume by employing multiples than trying to get the same SPL from a single pair? :scratch2:
Not only that, bass extension is also far superior than what is to be had by a single pair of speakers - no matter how much the volume is increased.
I realize the math doesn't support any of this but I can't explain it.
Three amplifiers are used in this system and all speakers are 8 ohm. The rear pair are Polk RTiA9 (90 dBw); fronts are Polk RTiA7 (89dBw) and Snell J7 (89dBw). Amps are MC 2125 (x2) fronts; MC 2155 rears. All power meters calibrated.
The Gains of the amplifier for the rears are set so that the sound is balanced to the fronts. In fairness - the gain of the right rear speaker is set higher than the left rear so if the front amps register 1.2 watts, the right rear might be at 1.75 or so; the left rear would be 0.5 watt to compensate of the difference in distance between L & R to listening spot.
Are there any sonic advantages to be had by speakers not "having to work as hard" at a given volume by employing multiples than trying to get the same SPL from a single pair? :scratch2:
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I realize they're not 100% but they should provide at least some indication of relative output - no?