Tri-way question.

[Dunerider5 10+ year member]

I have rainbow slc 265's, and I want a single 12" sub, but Im poor... is a 2-channel amp in tri-way going to be the best way to power a sub and my speakers? Some *** I work with is swearing that the sub will be drawing power from the speakers'.

Are there any cons to tri-way?

Basically I was planning on getting a KAC-7252 which should send 170x2@4 to my speakers and 500@2 to an 8 ohm sub correct?

Anyone have a better idea for a similar price?

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[Prowler573 5,000+ posts]

The sub you plan on using is an 8 Ohm driver? If I may ask....why that particular sub?

A better plan, IMO, would be to get yourself a budget-minded 4 channel and use 2 channels to drive your fronts and bridge the other 2 channels to drive your sub.

 

[Dunerider5 10+ year member]

Well I read on these forums somewhere that the sub needs to be 8 ohms, so the amp sees 2 ohms per channel. Ill find out about that later though, no sub yet.

I can't get any help here?

 

[Dunerider5 10+ year member]

It HAS to be 8 ohms (DVC 4 or SVC 8 works) unless you have a bad *** amp. If it's less than 8 the amp will see less than 2 ohms stereo.
Just look at the sub - (Assuming it's 8 ohms) if it's running in tri mode you're just running the sub from the bridged channels - since each channel effectively sees half the load that's the same thing as running in 4 ohms stereo. When you add to that the other two speakers already running in 4 ohms stereo - the result is your amp is seeing 2 ohms stereo.

If you drop that sub to 4 ohms that means your amp is already running at 2 ohms stereo and when you factor in the other 2 speakers you get a 1.33 ohm load on each channel.

Right or wrong?

 

[acold7dusta 10+ year member]

just buy a 4 channel and bridge the rears

 

[Bake 10+ year member]

If you are running an amp that is stable to two ohms stereo/four ohms mono, in what is usually called mixed mono, you can run the stereo channels at two ohms but you need to keep the sub channel at four ohms. I haven't seen you mention it but you do know you will need passive crossovers to set this up, correct?

 

[Dunerider5 10+ year member]

Yes I know that. What I wanted to know was wether or not having the sub on the same amp will affect the sound of my components, thats basically it.

Is there any reason I shouldn't use a tri-way crossover?

I wish I could get some real help here.

 

[Bake 10+ year member]

No, it is not going to affect the sound of your components. No reason not to use passive crossovers. I only asked to be sure that you were aware it would be necessary to use them in a mixed mono application. I told you that you could run the stereo channels down to two ohms and that the sub channel would need to be no lower than four ohms. Seems that I answered the question that you asked. What is this real help that you are seeking?

 

[Dunerider5 10+ year member]

No, it is not going to affect the sound of your components. No reason not to use passive crossovers.

That is what I wanted to know. Why is everyone on and off these forums telling me to get a 4 channel? Wtf?

Ive done some searching and Im surprised at how little discussion there is about tri-way... seems like a great deal to me.

 

[Bake 10+ year member]

Most are accustomed to using the built in crossovers on four channels. Running two channels in stereo and bridging the other two for a sub. It makes for a very simple install. In the "days gone by" running systems with mixed mono configurations was very common. There weren't a lot of amps with built in crossovers back then. It also made for some very impressive systems using a single amp. I have seen amps such as the old Rockford punch amps sitting all alone and powering some bad a$$ systems. Another reason guys used these setups was because competitions had classes based on power levels used in the car. That is why the old school competition level amps like Rockford and PPI were so severally under rated.

 

[thch 10+ year member]

depending on the frequencies and power in question, you might find that the inductor+capacitor costs, probably around $30 up to $50, may be a bit high. even then, the passive filter will be minimal. also, there is no easy way to turn up the volume of the subwoofer seperatly, so you are basically hoping the speakers just sound equally loud in the setup.

further, due to the commonly inductive load of the speaker, and the probably resonance of the midrange, you may find results are better with a pre-amplifier filter.

also, the passive lowpass has a high series resistance, which increases Qtc (sealed boxes) and reduces damping in ported as well. generally undesirable.

a 4 channel amp is also great for expanding systems. if, at some later time you decided to buy a dedicated sub amp, you would have a 4channel amp to work with -- the ability to amp 4 speakers in the car (front-rear or biamping). the 4 channel amp also doubles as a powerful 2 channel amp for components. it really is a nice thing to keep around!

tri way isn't discussed because no one uses it. it requires a passive filter at relatively low frequencies, which means large components and high costs, which can only be offset by making the crudest crossover possible. level matching is also not a feature, and the woofer needs to be 8ohm or higher.

 

[thch 10+ year member]

Right or wrong?

the explaination given -- that each channels sees 8/2 ohm (sub) in parallel with 4 ohm (component set), for an effective 2ohm load, is somewhat correct. at least if you don't use a passive filter.

the only real "gotcha" comes from the line of reasoning that components are a similar setup -- a 4ohm mid and a 4ohm tweeter in parallel. but this gives a 4ohm load because of the filter. since you are adding a filter on the components and the sub, there should be no frequencies where the impedance is less then 2ohm, assuming a 4ohm woofer and 2-4ohm speakers were used.

 

[n2audio 5,000+ posts]

Are there any cons to tri-way?
Basically I was planning on getting a KAC-7252 which should send 170x2@4 to my speakers and 500@2 to an 8 ohm sub correct?

Sounds like your power expectations are way off.

That amp is 170x2 at 2, 250x2 at 2 (or 500w bridged).

500w is the most power you can safely get out of it, no matter what wiring method you use.

Tri-mode is basically running the amp at 2 ohms stereo - 4 ohms per channel from the small speakers, and 4 ohms (each channel will see half the 8 ohms) per channel from the sub.

The speakers get 1/2 the power, and the sub gets the other half. So 125 per spkr and 250 to the sub.

That means you'll have to run the amp full range with a pair of high pass passive crossovers for the speakers, and a low pass passive for the sub.

As it seems you've heard more than once...In the price range of the Kenwood amp you can get a decent 4 ch and make this a whole lot easier.

something like http://www.onlinecarstereo.com/CarAudio/ProductDetail.aspx?ProductID=12788 would do a great job IMO

here's another good one --

http://www.onlinecarstereo.com/CarAudio/ProductDetail.aspx?ProductID=12979