REW and Acoustic Crossovers

[Stycker]

Is there a way to have REW calculate potential frequency and slope curves to achieve desired target level. I used the Jazzi chart to import house curves into REW. I ended up with 5500 Hz BU2 on the left tweeter and 4000 Hz LR4 on the right tweeter. The target was a 3500 Hz HP LR4 electrial crossover. I used a lot of trial and error to come up with those numbers. Both sides match acoustically. Is there a faster way to achieve the end goal of finding the proper frequency and slope?

[Cathul]

Yes there is, at least to some degree...
Tune the tweeters flat to the target curve one octave below the desired crossover without setting any crossover in the EQ overview window (Target type in "Target Settings" set to none) and with your full housecurve set in the preferences.
When the tweeter follows that curve (be careful with your volume while measuring and set a crossover roughly at 1.5x fs of the tweeter) you can easily set a LR 24db crossover and it will follow the desired slope perfectly.
Other than that REW is not able to propose a "best" crossover setting for you.

[Stycker]

Ok Thanks. i've used REW in the past, but not to this extent. Using asymmetrical frequencies and slopes has been a game changer. It just took such a long time. I had to guess where to start the cutoff and also guess what I thought the slope looked like. In between guessing I had to remeasure with the Mic each time I made a new guess. Eventually I made the proper choices. With 10 speakers it took a very long time. At least I know the tune is good now, maybe I can stop tinkering so much.

[Jdunk54nl]

Other than that REW is not able to propose a "best" crossover setting for you.

It can.

Measure your tweeter without any EQ and the lowest safe crossover you can do (note this is not a tweeter in my example).

Click the EQ tab at the top.



Have your target loaded in settings and you should have something like this (whatever your blue line target/house curve is is what you will use, this is a home speaker so I wanted a different target than my car)



Click EQ filters at the top and scroll to the bottom to where you see crossovers. Choose your type and order and frequency in there. These are the electrical settings you will put into your DSP to match the acoustical desired target. (note: This has the acoustic response at too steep of a slope and would need more work, this wasn't my final tune, but was what I had time for that day)





The Bright red is what REW predicts and the dark red is the original (sorry about the close colors)




This is just what REW predicts the results will be by using the above crossovers and EQ filters.



Then you would measure and see if it is right and make minor adjustments. Usually minor adjustments are needed.

And this was my post EQ measurement after doing just that: It needed some minor work after this. Some of the filters combine to work better than REW predicted and others are slightly worse than REW predicted.

[Stycker]

Thank you. Thats great news. After I type in the crossover information in REW Eq filters, do I go directly to the car for a mic measurement for confirmation. If correct then do Eq in Filter Tasks only after crossover information is finalized?

[Jdunk54nl]

Thank you. Thats great news. After I type in the crossover information in REW Eq filters, do I go directly to the car for a mic measurement for confirmation. If correct then do Eq in Filter Tasks only after crossover information is finalized?

After you get the stuff in REW figured out and put into your dsp, you can either confirm the crossover is right (it is usually really close) and also put in the EQ filters right then, or re-measure. That part is up to you. I normally just put everything in at once to save time. Then adjust after that.

[Stycker]

This will be a big time saver. I assume I'll have to add a second filter at the same time for a midrange?

[Cathul]

It can.

Measure your tweeter without any EQ and the lowest safe crossover you can do (note this is not a tweeter in my example).

Click the EQ tab at the top.

Oh ok, you're talking about the manual way to do that, not the automatic way which REW cannot do unlike the EQ bands by pressing "Match response to target".
And btw. you should EQ before you set the crossovers in that window. If you ever press "Match response..." or "Optimise gains" or any of these features after you've set the crossovers there, you'll totally mess up your predicted EQ.

[Cathul]

Thank you. Thats great news. After I type in the crossover information in REW Eq filters, do I go directly to the car for a mic measurement for confirmation. If correct then do Eq in Filter Tasks only after crossover information is finalized?

If you do that don't ever reset the crossovers in the filter window of REW.
This will mess up you predicted EQ.
In this case you don't have to set any crossover settings in REW at all except for the target curve (choose Speaker driver and set LR24 alignments at the desired frequencies), set level of target curve to your measured curve and match response.

[Stycker]

Thank you guys. I'm really getting a handle on this. Still learning after all these years. There is a wealth of knowledge to be found here