HPF and LPF at same freq in a passive crossover?

[Tbonem3]

I was passive with the crossover point at 4.3khz I believe. Went active, but I'm having to set the LPF on my 6.5s at like 2khz to get the same sound as when I was passive. They're off axis and the beaming is way too much if I set the LPF at 4khz, even in the 3s.

So, on a passive crossover, is the tweet HPF'd at 4khz (or so) and the mid LPF'd much lower (around 2-2.5k)? Or are both HPF and LPF'd at 4khz (in this example)?

I understand the slopes can be made less steep if there's no or little underlap or less steep if large underlap.

The slope, as far as I know, was 24db/oct on the passive crossovers and I'm limited to 18, but 18 is still relatively steep.

Thanks for your insight,

Tyler

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[fly_marlin]

I was passive with the crossover point at 4.3khz I believe. Went active, but I'm having to set the LPF on my 6.5s at like 2khz to get the same sound as when I was passive. They're off axis and the beaming is way too much if I set the LPF at 4khz, even in the 3s.
So, on a passive crossover, is the tweet HPF'd at 4khz (or so) and the mid LPF'd much lower (around 2-2.5k)? Or are both HPF and LPF'd at 4khz (in this example)?

I understand the slopes can be made less steep if there's no or little underlap or less steep if large underlap.

The slope, as far as I know, was 24db/oct on the passive crossovers and I'm limited to 18, but 18 is still relatively steep.

Thanks for your insight,

Tyler

First, are you sure you were at 4.3khz passive? Frequencies and slopes depend on the passive x-over, they're not all the same. They're usually tailored to that specific mid/tweet combo. Are you talking about the harsh sound? It's coming only from the mid and tweeters are fine? You should really lean on what the passive x-over point was as a point of reference, otherwise, just tailor it to what sounds best to you. You want to use the EQ to alleviate the harshness as well.

 

[wew lad 5,000+ posts]

keep in mind you're likely giving those tweeters much more power than you were without the passive crossover, they will begin to sound harsh quicker due to this. Modifying the crossover frequency isn't really uncommon, i had to do it with a set of tweeters run active too.

have you tried reversing the polarity of the tweeters? sometimes it's necessary due to yadda yadda.. someone more technical can explain it if they want - basically try it and see if you like it.

 

[Tbonem3]

Totally get what you guys are saying. But my question is really...

If my passive crossover had an advertised crossover fq of 4.3 (or 4.5 whatever) with a 24db/oct slope, does that mean that they HPF'd the tweets @ 4.2k 24db/oct and LPF'd the mids at 4.2 as well, same 24db/oct slope?

This may be the case, I just would expect a lot of overlap in that scenario. I know I can tone down the tweets' gain (it's already a fraction of the mids' gain) and EQ down the overlap (don't think I should have to). I'm more curious if speaker makers simply advertise the crossover of the tweets (HPF) and the LPF for the mids is unknown (and lower, like 3k) or if both the HPF and the LFP are at 4.2k.

 

[wew lad 5,000+ posts]

the LPF for the mids can be anything, there are times where manufacturers may even cut out a frequency range with the crossover if it sounds better that way. The only way to know what the crossover is doing is to understand its circuit or have the company who made it tell you.

 

[fly_marlin]

Totally get what you guys are saying. But my question is really...
If my passive crossover had an advertised crossover fq of 4.3 (or 4.5 whatever) with a 24db/oct slope, does that mean that they HPF'd the tweets @ 4.2k 24db/oct and LPF'd the mids at 4.2 as well, same 24db/oct slope?

This may be the case, I just would expect a lot of overlap in that scenario. I know I can tone down the tweets' gain (it's already a fraction of the mids' gain) and EQ down the overlap (don't think I should have to). I'm more curious if speaker makers simply advertise the crossover of the tweets (HPF) and the LPF for the mids is unknown (and lower, like 3k) or if both the HPF and the LFP are at 4.2k.

You should call CDT and ask. I don't believe they'd cross anything over at the same frequency.

 

[TaylorFade 10+ year member]

Passives are usually just a "split". So if it says, 4.3khz, then both drivers are crossed there. The way most are designed is both drivers are -6dB down at the crossover point so that you don't have a peak at the crossover (Linkwitz-Riley or "LR"). As opposed to a Butterworth alignment where they sum at the crossover.



Passives, the large majority of the time, are 2nd order filters (-12dB). It would need to be a large and expensive passive to be -24dB. I have a very large and expensive one that is -18dB.

How do you know you're beaming? Are you losing information?

 

[Jepalan]

Just like TylorFade said, most passives use -12db or even -6db slopes. The midbass to tweeter cross point will be electrically matched (so, essentially same freq for HPF & LPF with consideration for filter type).

OP - if you are hearing a difference active with the crossover points matched, it is probably a level matching issue, not a x-over frequency issue unless you have some really weird acoustic null or peak going on.

What do you mean you have "beaming issues"? Beaming means you would be losing high frequencies from the midbass when off-axis. It doesn't make sense that you would LPF the midbass lower to treat beaming because you would lose even more HF energy.

 

[Tbonem3]

Mybad, I had the wrong understanding of beaming (to be fair, I was guessing). My mids sound too strong in the higher frequencies (the tweets are off) and I'm finding that I have to drop the LPF to 2.5khz for it to sound good. That's a lot of underlap and I was curious if the passive crossover had similar points.

Thanks for all of your guys' help. I'm finding that the numbers matter less than how it sounds.

 

[Jepalan]

Put the crossover freq for the mids back to match the tweets and try dropping the level (amp gain) going to the mids until they blend better.

How did you set your amp gains for the active mid & tweet channels?

 

[Tbonem3]

Put the crossover freq for the mids back to match the tweets and try dropping the level (amp gain) going to the mids until they blend better.
How did you set your amp gains for the active mid & tweet channels?

#1 , I hate to do that because I love heavy bass guitar and drums and I want the woofer loud/strong from 70hz->2k or whatever. I'm thinking I can leave them loud and then EQ down 2khz - 4khz. I will try your suggestion, however, as tuning is never finished right? //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

#2 . I have 4v preouts. I set gains on all channels to min on the amps. Raised the volume at the HU to 23 (I was told 23 on the Kenwood x794 is about as high as you'd want to go (35 is max) and that has been the loudest I've wanted to go). I found I needed to raise woofers' channels about a quarter up from minimum, but I barely raised the tweets' at all. I raised my rear 6.5s almost a quarter as well, but they're on 50x2 compared to the front woofers' 75wx2 so they're naturally lower which is what I want for rear fill (I do like rear fill). I LPF the rear at 1khz both to keep it from pulling the sound stage too far back and to pronounce my favorite frequency range for my music (hardcore punk).

Thank you

Tyler

 

[wew lad 5,000+ posts]

i wouldnt cross the rear that low... seems kinda pointless and just a waste. your music will be pulled to the back based on volume not frequency (in this case, because you have plenty of front stage). cross over the rear speakers where they sound happy, and use the gain to make it so you don't hear the backs at all unless you turn around and listen for it.

I agree with you about the heavy bass guitar and drums, even low vocals i want to feel. adjusting your crossover to 2khz though, won't really change your low end response, unless we're talking about high active levels where you want a small BPF to reduce distortion for just plain loud. You may not want to go all the way up to 4khz, maybe 3khz is fine. it really is about what sounds the best for you, if it sounds better at 2khz that might be necessary BUT i would attempt to follow others advice and use the gain to match it better

did you try changing your tweeter polarity yet? there is a reason why i asked before

 

[Tbonem3]

Ok thanks. Ya, I switched polarity on the tweets, but they sounded like ***, no life at all. Maybe I needed to gain them up some? Not sure.

I guess I can just cross the tweets and mids at conventional frequencies and EQ it all to sound how I want it to. I do have 16 bands to play with lol. I just felt that the higher frquencies were too much, the sound too nasaly, out of the mids (tweets off), when what I wanted was pounding bass. I'll just keep playing around. Appreciate all of the ideas and help.

 

[Jepalan]

Is this what you are running?

DEH-80PRS

Memphis 16-MC2004 50x4---->1.1" CDT HD-1 & 6.5" CDT CL-6E (rears)

Memphis 16-MCA3004 75x4--->6.5" CDT HD-6CF (front) & Clarion 10"

Are you running the 80PRS in network or standard mode?

How are you connecting the 80PRS front/rear/sub (or Hi/Mid/Low) channels to the amps?

Why not wire all this up so you can take advantage of the 8-PRS auto-tune and time alignment?

Are you willing to ditch the rears?

 

[Tbonem3]

Network, low level input. highs to 2 channels (50wx2) Mids, with y-splitters, 2 channels (50wx2) for the rear and 2 channels (75wx2) for the fronts. Lows to 10" sub.

I'll try the auto eq later - I wanted to see what I could do on my own since this is my first time going active. I also would need to disconnect the rears for both auto eq and t/a. From what I've read of the 80prs's auto tune, it's not the best for my type of music - seems to lower bass and focus on vocals/highs. i'll get there, just trying to do it and learn myself.