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Discussion Starter · #1 ·
I've installed a new Kenwood KDC-X704...basically I am trying to understand how to best set this up (in addition to what just sounds best by ear), by better understanding how (if) the unit "knows" what frequencies go to tweeters, etc. see below...

Rectangle Font Screenshot Parallel Number

How does the unit know what goes to a tweeter? there is only 2 channels (L and R) Front or L and R Rear Or Subwoofer (L and R). In my system I am driving fronts through a JL 500/5 through an a/d/s 346is passive crossover system...this I understand" because we are actuallly filtering and splitting the signals frequencies at the a/d/s crossover ...but how will the Kenwood settings effect this? Can I just get rid of the a/d/s crossover? (pretty sure not)...Sorry..my ignorance on how the Kenwood h/u is key here...I want to send all the signals to the passive crossover and let it separate them...no? I have a feeling that if I'm double crossing the signals that the slope is additive? so I would have a narrower selection of freqs?
Appreciate any tutalage on this!
Thanks
Tony
 

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I've installed a new Kenwood KDC-X704...basically I am trying to understand how to best set this up (in addition to what just sounds best by ear), by better understanding how (if) the unit "knows" what frequencies go to tweeters, etc. see below...

View attachment 317516
How does the unit know what goes to a tweeter? there is only 2 channels (L and R) Front or L and R Rear Or Subwoofer (L and R). In my system I am driving fronts through a JL 500/5 through an a/d/s 346is passive crossover system...this I understand" because we are actuallly filtering and splitting the signals frequencies at the a/d/s crossover ...but how will the Kenwood settings effect this? Can I just get rid of the a/d/s crossover? (pretty sure not)...Sorry..my ignorance on how the Kenwood h/u is key here...I want to send all the signals to the passive crossover and let it separate them...no? I have a feeling that if I'm double crossing the signals that the slope is additive? so I would have a narrower selection of freqs?
Appreciate any tutalage on this!
Thanks
Tony
It appears that there are only high pass xovers for front and rear, so you would set those at 80 hz (or your preference) for your midbass speakers, because the passive xovers likely only low pass the mids and high pass the tweets. You would be sending an 80 hz and up signal to the passive xovers. The combination of head unit xover and passive xover would band pass your mids and have no effect on the tweets.
 

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In a passive setup those settings are to just to adjust the level of the frequencies that go to the tweeter. You need to set (assuming you know) the crossover frequency of the passive filter for it to work the way intended.

If that particular headunit supports 3-way crossover you could have a 2-way active front stage straight from the unit, just need to have separate wiring for midwoofers and tweeters.

For reference here is a graph of the tweeter adjustment in a Kenwood passive configuration:

Rectangle Slope Font Parallel Plot

There is more interesting info in graph form here, if interested: https://www.drive2.ru/b/495434717869375938/
 

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Discussion Starter · #6 ·
How does the head unit know what is going to the tweeter? That is what puzzles me. I have a front left and front right preamp....going to my amp...two channels..every frequency that I want to hear on those two channels...then off my amp - same two channels get split at the crossover..(at this point they are directed tweeter vs woofer but not until then).
 

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How does the head unit know what is going to the tweeter? That is what puzzles me. I have a front left and front right preamp....going to my amp...two channels..every frequency that I want to hear on those two channels...then off my amp - same two channels get split at the crossover..(at this point they are directed tweeter vs woofer but not until then).
You tell it where the tweeter crossover point is and with that information it can attenuate the the range above that point. You can see it in the graph.

If you set the crossover of the tweeter to 2.5kHz and set the gain of the left tweeter to -3, it will attenuate everything above 2.5kHz by 3dB(or so) on the left output. It doesn't "know" anything here, it just does what you tell it to do.
 

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Seems to me that what ckirocz28 suggested (and how I would run them in your situation) would be:

Connect the high-passed Front RCA outputs in "Tweeter" mode to two amp channels, and the tweeters directly to the amp. Now the tweeters are protected and are only playing the high frequency range you select. To be on the safe side, you might also want to put a capacitor before the tweeters for extra protection, at a frequency below the high-pass you select in the HU.

The Rear high-passed RCAs to two more amp channels, with the midwoofers connected to these outputs, but place the a/d/s crossover between the amp and speaker, with the speaker wire from the amp to the woofer input, and the woofer output of the crossover to the midwoofers. This would provide a low-passed signal to the midwoofers, while the HU provides the high-pass, resulting in a band-passed signal to the midwoofers.

Sub output to sub amp, pretty straightforward.

Once you're set up this way you can tweak the crossover settings to get the drivers to blend together. I don't know what the a/d/s low-pass frequency is, but guessing it's 2,500Hz, in which case I would start the tweeter crossover also at 2.5KHz. The midwoofer low-pass would be the only crossover point that you can't adjust, but you should be able to get it to blend pretty well with one of the tweeter high-pass settings.

Being set up like this will still allow you to adjust individual driver levels and time alignment.

Like JetBadger said, the HU doesn't "know" or "care" what it's connected to, it merely outputs the signals at the parameters you select. You could technically connect the outputs of the "Tweeter" setting to a subwoofer, and it wouldn't make a difference to the HU - no reason to actually do that, just mentioning it to demonstrate that the HU "knows" nothing about what happens to the signals after it outputs them.

Good luck!
 

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I think his point is that there is no option to choose the tweeter crossover point within the headunit. Even though it says that it has those options for tweeter crossovers. So how do you use it.
Maybe im wrong
 

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The manual is confusing, for sure. It seems to me that if you select "speaker size" for any driver, it automatically sets the frequency and slope, both of which are not specified. I'm guessing that if you set them all to "None", you can then set the crossovers manually as seen in the pic of the manual in the first post, but I could be wrong. It says that "none" means "not connected", which potentially suggests you'd get no output from this setting, but it doesn't make sense that you could both set the size (with its corresponding automatic crossover) and also use the crossovers independently. It seems like the speaker size settings are ballpark settings, while the manual crossovers give more control. There are only tweeter three size choices, but nine choices in the manual crossover section.

To suss out what the HU is doing, I'd probably connect a single midwoofer (safer than using a tweeter) without the a/d/s, and see what the output on each setting in the HU actually does, before attempting a final connection.

Font Parallel Number Screenshot Rectangle
 

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Part of the confusion is that the way it's presented almost suggests that there are crossovers for Tweeters, Front, Rear, AND Subwoofer simultaneously. There are only 3 pairs of RCA outputs, so to me it looks like it gives two main choices: if you are using passives in the front and rear of the car, you can set a low-frequency high-pass for each set; if you are using front separates, you would set the Front RCA outputs to Tweeter, use the Rear outputs for the midwoofers, with no provision for actual rear speakers.

I had a JVC unit that could do a 3-way, seems very similar to what your Kenwood can do. JVC and Kenwood are the same company and many models seem to be identical internally, decent chance that the much more clear JVC manual will apply to the KDC-X704. The pricier and larger JVC w/touchscreen seems to have a few more options, but it appears the concepts are the same. After looking at this manual, it looks like when you select a speaker size, it does automatically set a crossover, but you do retain the option to go into the Crossover section and adjust that pre-set crossover, so it looks like my previous post about this point is probably incorrect.

Link to JVC manual
 

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Discussion Starter · #12 ·
Thanks - you have distilled what I am confused about! I will check out the JVC literature...thanks again!
 

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That is called a shelf filter. You set the frequency of the "shelf" then you choose the level.
This is for passive crossovers only.
No attenuation is given under the frequency you select.
It is not a crossover. Well....you could use it as a low pass xover for the midbass if you were to run them on the front channels.
You could select 2.5khz and attenuate the channel by I think 10db. That would lower 2.5 and above on the midbass by 10db. Kinda like a low pass xover with a slope of 0.
 

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That is called a shelf filter. You set the frequency of the "shelf" then you choose the level.
This is for passive crossovers only.
No attenuation is given under the frequency you select.
It is not a crossover. Well....you could use it as a low pass xover for the midbass if you were to run them on the front channels.
You could select 2.5khz and attenuate the channel by I think 10db. That would lower 2.5 and above on the midbass by 10db. Kinda like a low pass xover with a slope of 0.
This. That head unit is not one of the Kenwood models with 3-way active crossovers, it is intended for a traditional passive component set and adds a tiny bit more flexibility with the extra shelf filter.
 

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Thanks for chiming in on this, guys. I've never heard of an arrangement like this - so what the manual states as being a tweeter crossover is in fact NOT a crossover? This seems like he actually would need to use the a/d/s crossover for both mids and tweets, with only a high pass on the low-end for blending with a sub. And no time alignment or individual speaker level controls. Kinda explains why there are choices for slopes on every crossover except the tweeter "crossover". Weird. The manual clearly uses the word crossover in regards to the tweeter; borderline false advertising?
 

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Pretty lame move by Kenwood. Seems like a recipe for blown drivers.

raudi1 - apologies, please disregard what I posted earlier. When I bought my old JVC, one of the main points was having an actual (albeit not external DSP flexibility level) 3-way active setup. Looks like your HU does NOT have the true 3-way capability I thought it had, and you will need to use the passive a/d/s crossovers for both mids and tweeters. It would seem that since the a/d/s has bi-wire capability, you could still connect the tweeters as front, mids as rear, and should still be able to do time alignment and have control over the individual driver output levels via the HU. Sort of a semi-active setup, with two sets of speaker wires feeding each crossover, each from its own amp channel.

HU Front RCA, set as Front high-pass (I would use the maximum 250Hz setting) --> amp channels 1 & 2 --> tweeter sides of crossover inputs --> tweeters
HU Rear RCA high-pass (you will have to determine best frequency via ears/measurements) --> amp channels 3 & 4 --> woofer sides of crossover inputs --> woofers
 

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Discussion Starter · #19 ·
Continuing this discussion...and thinking if there is still a way to get rid of the passive crossovers. My current system is Kenwood KDC-x704 to JL 500/5. Front preamps currently to front amp section to a/d/s 345is to midbass and tweeters. Rear preamps to rear amp section to a/d/s a5im coax (tweeters on these are shot and need to be replaced). Subwoofer preamp to sw amp section to a/d/s/ 310rs 10" subwoofer. Thanks for any ideas...
 

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Some Kenwood decks have a 3-way crossover mode where you then use the rear outputs for tweeters and have all the crossover settings from the unit. Looks like yours doesn't have that functionality. You could use something like an adjustable analogue crossover on amp inputs, but I don't see any benefit from that. There are many ways of getting rid of the passive crossovers, but why do you want to do that in the first place?
 
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