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Opinions plz: bridge vs bi-amp again. But how big should I go?

Old 05-09-2011, 06:42 PM
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Opinions plz: bridge vs bi-amp again. But how big should I go?

Hi everybody.

I picked up a Zapco AG650 (50x4 + 375x1 bridged) a while ago to start a build in my Mazdaspeed 6. I'm having trouble deciding how to configure the system though. I plan on running my 10" Boston G3 2ohm (DVC) off the sub channels bridged since they are 1 ohm stable, but 50x4 just doesn't seem right in the cabin. I have narrowed my component selection down to Morel Hybrids, Rainbow Germaniums, Macrom M1's or if I can find some Focal KRX2's Utopias or Hertz 165's used they'll fit my budget and taste too. I definitely want a bigger front sound stage and lighter rear fill so I'm looking at an extra amp to balance it out. (I've found an AG150, AG200, and an AG350 to match my 650 but can't decide which way to go.)

So my question here isn't about the sound quality difference of bi-amping. I just want a little input and suggestions on my second amp selection. I could bridge the remaining channels on my 650 for the front and run the rears off either the 150 or the 200. OR I could run the rears off the 650 and bi-amp the front with the remaining 2 channels and any of the 3 amps I'm looking at. I don't have room for any more amps so I won't suggest bridging for the woofers and adding an extra amp or a bigger 4 channel to put power to the tweets and rears.

Do you think if I get the 150 for tweeter duty (35x2 ish) the mids will starve with 50W? Is 50x2 too much for the tweeter if I only put 50 or 100 to the mid? I thought I read that the tweeter/mid ratio should be 3:1 or 4:1. Or should I just take the short cut of bridging the 650 up front (170+ through passive x-overs) and use the 150 for the rear. (This is most cost effective and the simplest solution.)

I appreciate the input.
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Old 05-09-2011, 08:25 PM
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I'd say it's all depending on whether u wanna run active or passive. I've always wanted to try an active system. It would really open up your tuning options. It sounds like it's gonna be a top notch system! Keep us updated on your choice.
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Old 05-09-2011, 10:59 PM
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I would play around to see what you like best.. personally I'd probably bi-amp them.. you get more control over crossover points and although you are comparing 170 x 2 watts vs 50 x 4 watts you should consider that the effective power of a bi-amped setup is up to double the actual power... (In other words a bi-amped 50 x 4 is comparable to 200 x 2)

Given the amp will pull less power, be more efficient, along with having lower distortion figures its basically a no-brainer...

Last edited by Haunz; 05-10-2011 at 02:36 AM.
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Old 05-09-2011, 11:40 PM
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Hmmm.... I get that the amp doesn't have to work as hard because it doesn't have to reproduce the full range. I never would've guessed it would double the power though. Or does that extra power increase come from changing from the 4 ohm loaded passive x-over to speakers that might be rated at 3ohm and 8ohm or 2x2ohm or however they get split up? If that's the kind of power boost you feel bi-amping gives, I think I'd be perfectly happy with 50 on the mids and 35 on the tweets. Well the tweets might be a little too hot at that ratio.
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Old 05-09-2011, 11:45 PM
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Oh yeah- do I really need a crossover before the amp or are the crossover settings on the amp good enough to go active? If I get a passive x-over that is bi-wirable/bi-ampable does it really restrict that much? I guess I do have more questions than I thought.
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Old 05-10-2011, 12:16 AM
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You can get passives that are bi-ampable but so long as the amplifier has suitable active crossovers you don't need to use passives... there are multiple advantages to using active crossovers and from a SQ standpoint they are by far the best way to go... The only caveat is that if you don't set it up properly you are a lot more likley to cook a driver then you are with a passive set...


In terms of the effective power of a bi-amp setup... consider with a non bi-amped setup the 'highs' are superimposed on the 'lows'... so if you have a low note at 100 Hz comming out of the amp at 20V RMS and a high note comming out at 2Khz and 15V RMS you need a dynamic range of 35V to reproduce a clean signal... with a bi-amp setup which separates those frequencies you would only need 20V of range for the low note and 15V for the high note...

A more detailed explination can be found at Elliot Sound Productions web site under the bi-amp section...
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Old 05-10-2011, 10:13 AM
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Alright. So what's going to give the best power balance? 50 tweet, 50 mid? 35 tweet, 50 mid? Or 50 tweet, 100 mid- and find 1.5" more amp space in my trunk? Is 150W bi-amped an overkill? Some say go big or go home, leave some headroom etc, and I like it loud once in a while, but really? The equivalent of 300W to a 2 way component (x2) just sounds a bit stupid.

I just realized that my AG650 built in x-over has a x10 function so it's good up to 5500Hz high pass while the other 2 channel AG's only go up to 270 Hz. Guess I'll be putting 50W to each tweeter regardless cause I'm too cheap to get an external x-over.

Back to the balance of it all... do I go big on the mids with 100x2 or turn the tweeter channel gain way down and go 50x6 (tweets, mids, rear) or 50x4 up front and 35x2 in the rear fill?

Last edited by trent.g; 05-10-2011 at 01:00 PM.
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Old 05-10-2011, 12:24 PM
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150 ea. doesn't seen that overkill. Especially with the caliber of equipment you're running. To get the full potential out of your equipment it looks like it will need some power. Power equals clarity. Running high end components off 85 per pair seems underkill if anything. We've run over 200 RMS to a set of components before. It's not uncommon practice. Your amp will run cleaner and cooler if it's not being pushed to it's max, possibly into distortion if you really wanna turn it up one day.
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Old 05-10-2011, 03:10 PM
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Use your AG650 for your Front Tweeters, Rear Fill and Subwoofer....then pickup a matching 100w x 2 (or bigger) for your front mids and call it a day. Too much power is never bad...within reason.

When making purchases for the 4-way active system I just abbandonned for the time being, I decided to go with an Audison LRx5.1k 5 channel to power 60w x 2 for Front Tweeters, 170w x 2 for Front dome midrange and the 750w x 1 channel for the sub. I then picked up an LRx2.9 for my (4) Hertz ML1600 midbass to run 450w x 2 @ 2ohms (2 in each front door, effectively 225w per driver).

The one thing I can count on, if I ever decide to finish this off and install it, will be that I will never have to worry about clipping amps and dirty power.....lol.....as I think I took care of the headroom factor and then some.

Is 150w or 200w x 2 overkill for a 2-way passive front stage ? ......I don't know. Is 450w x 2 overkill for Front Midbass only ?
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Old 05-10-2011, 03:30 PM
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Thank-you. After some additional reading and your input here, I'm leaning toward the AG350 for front mid duty to keep a better balance between it and the tweeter power ratios. It helps that the 650 has the high pass filter capabilities for the tweeter range and I don't think I'd benefit much with external x-overs since the zapcos are all built with linkwitz-riley x-overs already. Never thought I'd do something as complicated as a fully active system when I started planning this. Now to try and make a little extra money to support my expensive habits...
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