I'd like to know if I can safely bridge this amplifier into two channels and run passive before I drop cash on a DSP.

No, a 2 ohm speaker is 2 ohm with or without the passive crossover.

 

Ok thanks for the advice. Looks like I'll have to use the amplifier crossovers until I get the DSP.

I'll continue to read up on active vs passive, but the idea I'm getting is that is just not worth it unless you know better. And I don't.

However, my goal is to have a nice sounding system that doesn't wear my ears out. I'm guessing a DSP is the only real way to achieve that?

 

The good news is that it's unlikely you would be able to use the extra power by bridging the amp. 100w should be plenty for each side. That leaves you with a couple extra amp channels for something else if you decide to add on, or you can reuse the amp for when/if you decide to go active further down the line.

 

Going active is a whole different experience, get the dsp, a umik-1 and a 5 channel amp then get back to us for tuning help. And most amplifiers delivers maximum power at 2 ohms so your set there


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Doubt full you have to bridge the amp.
And in reality if it is 2-ohm speakers, than a 4-ohm amp will be putting more power into them anyhow.

 

Thanks for all the tips fellas. I had just posted a multi-quote reply and and didn't post! Something about being sent to a moderator? I don't remember using any foul language...

Anyway, sounds like I'll be fine running the amplifier crossovers until I want to shell out on the DSP. Which I'll probably do sooner rather than later.

 

As a note most 4 channel amps will not safely run at 2 ohm bridged (unless the amp is rated to handle 2 ohm bridged, in which case it is usually 1 ohm stereo). If using a 2 ohm speaker / or speaker load then it is best to run in stereo.

 

I know thanks to the comments here, that my amp can't bridge to 2 Ω. But for interest's sake...

The above statement hurts my tiny brain. First you mention it's generally not safe to run 2Ω bridged, but the last thing you say is it's best to run a 2Ω load in stereo, which is exactly what I would be doing by bridging four channels to two?

Thanks for the clarification.

 

See the focal speakers manual for bi-amping, so you get level control for the tweeter aswell.

 

Can I hit the thanks button twice?! I had forgotten all about that. Good call.

I would have figured that out eventually I guess - still waiting for the speakers to turn up in the mail.

 

So you can bi amp? That's a cool set to start with.
Sure the dsp is nice but start slow, just bi-amping and playing with gains and crossover settings (if there are some) will already give you good results, probably great.
Enjoy a bit and then when you feel you need more, next steps read all threads on rew and tuning with a umik etc and then install the 6x8.
Going too fast can be deceiving, train your ears first, step by step.
Well my 2cts

 

That's great advice Elgrosso, thanks. I'm not sure if it's bi-amping in the way you expect though. The passive crossover has bi amp capabilities, I don't know exactly what that does (apart from the obvious; I can use four channels) but MikeS reckons you can set levels independently.

What I do know is the crossover has adjustable slopes, so that's a good start?

I've started reading up on REW and measuring speaker response curves. Looks like fun times ahead!

 

Unless I've missed something, since you'll be bi-amping, once you get the DSP, you can ditch the passives.

 

This was the plan. There's probably quite a lot of tuning I can do without the DSP to get started. There seems to be a lot of support around here for active - looking forward to finding out why.

For tweeter level on the fly you can use fader control. Also if your deck has time alignment you can use that for all 4 speakers individually. You should get decent sound even without dsp. Which headunit do you have currently? Even most cheap alpine/pioneers have network mode allowing active set up.

This is currently the biggest concern. Wish I had done more research; I spent $900 on a POS Chinese Android head unit (RoadNav S160) that's probably worse sound feature wise than a cheap Pioneer.

It has weak output (I measured 0.26v max) on the RCA's. No sound features you mentioned, except fader.

Now my head is spinning trying to figure out how to boost this s**t signal. Strong DSP? Line driver? Alternatively, how do I hack USB Audio support into Android 4.4.4?!

Or if you choose to delay using a DSP, then just get an active cross over for now. The only difference is that there is no TA and EQ.

If I wanted to ditch the passives now, I could use the built-in crossovers on the amplifier. Are there any major disadvantages to this?

 

For tweeter level on the fly you can use fader control. Also if your deck has time alignment you can use that for all 4 speakers individually. You should get decent sound even without dsp. Which headunit do you have currently? Even most cheap alpine/pioneers have network mode allowing active set up.

 

Or if you choose to delay using a DSP, then just get an active cross over for now. The only difference is that there is no TA and EQ.

If it is 2 people in the ute, then one will not be getting a TA experience anyhow.

This approach makes the most sense if one can find a used active crossover for a decent price (compared to a DSP), which seems possible with most people now using DSPs.
(Obviously I have an active cross over... )

 

Sorry, I just realized that you don't need a DSP to ditch the passives, as the Focal FPX 4.400SQ has built-in 40Hz -5000Hz crossovers (very nice!! As a noob, I'm not used to this...), which I'd think should do the trick.

 

...As for disadvantages, I suppose there's always a chance you could blow the tweeters if they should inadvertently see a too-low (Hz) signal. If I'm not mistaken, some folks install capacitors on their tweeters to prevent this.

If there are other disadvantages, I'm blissfully unaware of them (as a total noob).

 

The disadvantage would be that your amp does not have bandpass capabilities. You can set a HPF on the tweeters, and either a HPF or LPF for the mids, but not both.

 

Thanks!

I feel like such a noob... :blush:

 

Selectable Crossovers: The amp features high-quality crossovers that can be configured as Low-pass, High-pass, or Full Range. There are independent crossover controls for the front and rear channels:

Channels 1&2: The crossover for channels 1+2 has a variable cutoff frequency from 40Hz to 5000Hz, with a slope of 12dB per octave. There are separate rotary controls for low-pass and high-pass operations. The frequency multiplier switch (F-MULT) activates a 10x multiplier for the setting value of the cutoff frequency. (With the switch at 1x, the frequency range is 40-500Hz; with the switch at 10x, the range is 400-5000Hz.)

Channels 3&4: The crossover for channels 3+4 has a variable cutoff frequency from 40Hz to 5000Hz, with a slope of 12dB per octave. The frequency multiplier lets you switch between a range of 40-500Hz (1x) and 400-5000Hz (10x).

Excerpt from: https://www.crutchfield.com/S-eCqGfNJBKom/p_091FPX4400/Focal-FPX-4-400-SQ.html

 

OP,it's either get a DSP and utilize all 4 channels,stay passive with them Focals and only use half the amps power or put them Focals on the Classifieds here,get some descent coin for them,4ohm passive up and bridge that thing!

 

Goldilocks = just right?

I think what JH1973 means by "half power" is that, at 2 ohms you can only use two of the four (un-bridged) channels (do I remember correctly that your Focals are 2 ohms?).

 

Not sure. Either that, or it means bi-amping will run tweeters on a full channel, wasting most of it. I'm still not sure exactly how bi-amping works, so this could be the case.

The crossovers have seperate channel inputs for the tweeters and the woofers. Does bi-amping to passive crossovers use all the available power or is it basically like running active where they are independent channels?

 

Another option you have is to run the tweeters off channels 1 and 2.Set the HP filter and turn on the x10 switch.Then use channels 3 and 4 with a LP filter and also the x10 switch.I wouldn't Blair it that way though cause you'll be sending very low frequencies to them midwoofers.

I find it strange that that amp has two different dials on channels 1 and 2 but yet no BP capability? I would think both sets of channels would have the same dials.Are you guys sure this amp is not BP capable?I'm too lazy to research it.

 

I find it strange that that amp has two different dials on channels 1 and 2 but yet no BP capability? I would think both sets of channels would have the same dials.Are you guys sure this amp is not BP capable?I'm too lazy to research it.

Yes, it does seem strange. But no, there doesn't appear to be any way to select a BP mode (just HP/FULL/LP).

Perhaps OP should contact Focal or Crutchfield to be absolutely sure (but my money would be on no BP).

 

Thanks for all the help guys, much appreciated. I had a quick look into contacting Focal, but their website directs you to their dealer network or resellers. I may try that but I'm wary of information from dealers. I don't expect them to know every detail about 1000's of products. However I do expect them to just make s**t up. :laugh:

The best way I guess, is to get my hands on a mic, set a narrow band and test with some audio analysis tools.

I'll be sure to leave a review - but I'd take my review with a huge grain of salt! I'm clearly no expert..

 

Ok,so let me get this straight.A $1300 2ohm set of Focal drivers is no good because it's 2ohms? Why would they make them then?And why would they make them in a component set with passive Xovers for the sole purpose of a SQ front stage?

OP,you're going to get answers from people here that will just confuse you because you're new at this and vulnerable.In time you'll learn that a lot of opinions about SQ and driver,amplifier brands are all subjective.You'll also learn that there is NO perfect and you CAN'T always make the most optimal decision.Those Focals you bought look like a fine set of drivers and that amp looks dam nice.As it sits right now you've got a great looking combo.Don't sell it and go with something else.Just install it and enjoy it until you're ready to go deeper.

 

Not saying that at all.
Just saying for my tastes I would stick with 4-ohm.

I think the OP has two basic choices.
1) shove them in like the system.
2) figure out what he wants from the system and start over.

I took approach #1 based upon his saying the $900 was wasted on the HU, and the the focal were in demand.

But I can take approach #2:
Those are quality bits of kit - so shove them in place. The crossovers are designed to not require an active amp.
Since it is a ute, and more often than not one has a passenger - do not even consider the need for a DSP to make it ideal for the driver. Save that $ for fuel and race meetings.

 

I hope they are worth it too. Thanks for all the suggestions. I'll more than likely drop the DSP in there because I can't leave well enough alone and I like to complicate things - just like most on this forum I suspect.

I'm actually considering installing the DSP but not hooking it up. Saves me from having to tear the ute apart twice. Also it will be good to learn the ropes with the relative safety of the passive crossovers (they have some slope/level switches), before diving into full active. That will also give me a baseline for gauging the effect of the DSP later on.

 

I had the same problem with my Focals. I wanted to run active with a DSP and a 5 channel amp. Once I realized the speakers were 2 ohms I had to rethink my plan. What I ended up doing was using the 5 channel for my tweeters, rears and sub. Then I found an Arc Audio KS 300.2 on Craigslist to run the mids at 2 ohms.


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