Tri-Amping : Equivalent power query. BS or not too much BS

Moondog55

Moondog55

diyAudio Member
Joined 2007
It's a genuine query as I've got my set-up now and I've been told that when Bi-amping / Tri-Amping you get a synergy that gives apparent power that seems as if you have a much more powerful single amplifier.
Back story there; as way back when I was drooling over the monster Rotel RB 1090 and the sales person was telling me to Bi-Amp and use two much smaller Rotel RB 1070's which would actually have more "Music Power" and said sales man was saying double the actual music power of the 1090 and at a much more affordable price

So my current Tr-amp set-up is 380W into 4R + 150w into 8R plus 150w into 8R
Which is a bit crazy as I'll probably normally use about 15 to 30 watts when listening at a reasonable level
I suppose 680 watts per channel RMS is a tiny bit of overkill but if comparing it to a single amplifier do I really have the equal of a thousand watts per channel??

For those interested
Cambridge Audio Azure [ rebuilt]
Behringer DCX
Jaycar Playmaster / BASS
Rotel RB1070 / Mid-bass
Kenwood L-07M / Mid/tweeter

Into
BASS
Cerwin Vega Vega124
Midbass
Vifa P26
Midrange / Tweeter
Vifa P13 / Vifa D-27
Midrange/Tweeter
 
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Read it but I'm still not sure that what I asked is answered in that article.
Is it really "Twice" the power or does Tri-amping change the equation?
 
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Hi,
I thought the 'actual VS effective power' section to be self explanatory ( figure 2).

But maybe i didn't understood your question?

The increased headroom or 'higher effective power' come from the separation of both signals in figure 2: with 4v peak/peak for full range, once you separate the 100hz from the 1000hz you now have 2v peak peak ( your headroom doubled for each ways= the 'apparent' power) for each ways.

Bi, Tri, quattro, whatever the number of ways will see same things happening for each. Of course with a tweeter you won't gain this much as you are supposed to not hear harmonics higher than 20khz ( or you shoot for dc to light bandwidth which isn't realistical). That said you'll still have some benefits ( imd reduction mainly) even with the high way.

But i prefer to call this headroom gain rather than 'doubling power' which i found misleading as the conditions 'seen' by each ways are differents from a full range signal and passive filter loudspeakers.
 
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Ahh OK The light just went on.
I think my thoughts were stuck on the notion that I'd be getting a 6dB effective gain with Tri-amping.
I know I need a better subwoofer or a bigger amp on the bottom end as the sub is a full 6dB lower in efficiency than the Vifa drivers
 
Power requirements are additive for complex signals. So if one tone requires 12 watts, another tone requires 8 watts, and a third tone requires 5 watts, then the amplifier will have to supply 25 watts to reproduce the signal.

With tri-amping, you could use a 12 watt amplifier, an 8 watt amplifier, and a 5 watt amplifier to reproduce the signal.

This is in theory. With modern compressed recordings it's rarely necessary to require the full power. But there's always that one track where it comes into play.

One thing is for sure. You can really reduce distortion with bi-amping or tri-amping. Plus there's zero loss from passive crossovers (this can add up to a lot of power). I've seen a couple boomboxes that used biamping. If el cheapo uses it, then there must be some real return from using bi-amping.
 
Far worse than that. Reproducing 12, 8 and 5 watt tones at different frequencies simultaneously (without clipping) requires a 72.6 watt amplifier to produce 25 watts of average power. All 3 voltage peaks of 13.85, 11.31, and 8.94 volts WILL align periodically.
 
wg_ski said:
Far worse than that. Reproducing 12, 8 and 5 watt tones at different frequencies simultaneously (without clipping) requires a 72.6 watt amplifier to produce 25 watts of average power. All 3 voltage peaks of 13.85, 11.31, and 8.94 volts WILL align periodically.
Click to expand...


Why yes, you're correct.

You have to calculate for peak power when designing sound reinforcement.
 
I went from 20W per channel with passive XO to 20W, 6.5W, and 6.5W in my active system, because I don't have additional power in the LF practically speaking I am not really aware of a significant jump in maximum achievable Spls, what I do notice is a pretty big bump in sound quality at high levels until the bass amps start to clip

Don't be fooled by the low powers, I can achieve about 114dBspl at the listening position before I run out of headroom. (I think this is about 2dB greater than before, but not exactly sure.)

Tri-amping for me was more about the possible increase in sound quality which has been born out over the past 3 - 4 years.

Plans are afoot for more power in the bass as the mids and tweets are more than 10dB more efficient than the woofers. (target about 65W, and probably not SE. Or new drivers for class A2 in the existing amps, good for about 3 - 4dB with the existing transformers and output tube and supply)
 
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