Help with crossover usage!!!
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New member Username: CarletonPost Number: 7 Registered: Jun-05 | Maybe I should have posted this in the head unit board, but I think it applies more here. I have Alpine SPR-17LS component speakers in my doors and dash, with Alpine SPR-69LP speakers on the rear deck. Those are combined with my Sony CDX-F7715X head unit. What I don't understand is how the crossovers on the component speakers are supposed to work. The head unit has settings for hpf and lpf that I have set to 125hz right now, they can also be set to 78hz or off. I think that I want them both to be the same right? But how do these interact with the external crossovers for the components. When I installed them, I didn't see any way to adjust the frequency of their filtering. Do I just leave them? I don't really want to take the door panels off again to do anything, but if I need to I will. The thing is that with lots of bass I get some of that bass buzz up front from the component woofers. I'm not sure if thats because they are underpowered (I am getting an amp this week), or if they are getting frequencies that are too low for them to handle. In addition, I plan to get an amplifier soon. How am I supposed to set up its crossovers? Thanks for all your patience and help. |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 8184 Registered: Dec-03 | set the amplifier XO to HPF, 125Hz. that blocks low bass from the components. the component crossovers just split frequencies between the tweeter and midrange drivers. |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 8185 Registered: Dec-03 | if you want bass, you need a sub.. don't try to get bass from components or door speakers. |
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New member Username: CarletonPost Number: 8 Registered: Jun-05 | I'm not really trying to get any bass, its just songs with more bass will still send the bass frequencies. Is the buzzing from the lack of power? or the limits of the speaker's range? Also, the crossovers split the frequencies, but I thought they were adjustable. Are they not? Should I set the hpf and lpf of my headunit to the same as the amp's? And what exactly does the lpf do? Thanks for the help. |
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Bronze Member Username: Dr_sharpUSA Post Number: 67 Registered: Jun-05 | if you use both xovers then you'll get an output that is the sum of the two filters. Meaning if they are both 12dB/octave you'll end up with a filter that is 24dB/octave |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 8196 Registered: Dec-03 | no he won't. just use one crossover, be it on the amp or the head unit.. and set the other to a setting outside the range of the one you're using so they don't interfere with one another. example is if you set the amp XO to HPF, 125Hz, 12dB slope, then set the head unit to something below 125Hz, and it won't have any effect on the final outcome. this is one reason I liked the older products that didn't do everything in one unit. you didn't get so much redundancy to confuse people. |
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Bronze Member Username: Dr_sharpUSA Post Number: 71 Registered: Jun-05 | uh.. yes it will. I just had that problem with my setup. My sub preamp was xed at 120hz from the HU (by default) and with the xover from the amp it cut it off too fast (slope was too big) so i had to use my rear preamps so that only my amp's filter was used. it doesn't matter whether you filtering the input or the output when you add filters the slopes add together. |
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Bronze Member Username: Dr_sharpUSA Post Number: 72 Registered: Jun-05 | if you're talking about components though the LPF from the HU won't affect the woofers HPF or the tweeters LPF. |
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Bronze Member Username: Dr_sharpUSA Post Number: 73 Registered: Jun-05 | simply because there is no frequency overlap. |
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Bronze Member Username: Dr_sharpUSA Post Number: 74 Registered: Jun-05 | "example is if you set the amp XO to HPF, 125Hz, 12dB slope, then set the head unit to something below 125Hz, and it won't have any effect on the final outcome." this is not true. if you set the HU filter at say 120Hz you will have a 12dB/octave slope until 120Hz at which a 24dB/octave slope will begin. |
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New member Username: CarletonPost Number: 10 Registered: Jun-05 | Alright, now I am thoroughly confused. Here's my situation... I have external crossovers that are part of my component set. I have them mounted to the door. I didn't see any way to adjust their filter frequency, and I'm not sure what you mean by slope. I got these for better sound quality, but I don't think I set them up right. I also have settings for hpf and lpf on my headunit. I'm not sure how I'm supposed to use these. It seems from your statements that I should use one or the other. I assume they affect all output, to both my front and rear speakers. The thing is, I'm not sure what the difference between them is. I would think you need only one filter to divide the frequencies... If someone could explain exactly how I'm supposed to use those, that would be awesome. In addition to that, I am planning on getting an amp (I don't have one yet). So it seems like I should just use the amp's hpf or lpf. Thanks for bearing with me guys.. your help is greatly appreciated. Unfortunately, I think you'll have to explain things to me as if I have no idea about any of this... |
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Bronze Member Username: Dr_sharpUSA Post Number: 75 Registered: Jun-05 | ok... the external crossovers that came with your speakers are made specifically to give the woofer and the tweeter the desired range of frequencies. So that crossover has a HPF for the tweeters probably around 3k-5kHz so that nothing lower goes to the tweeters... and a LPF for the woofers probably around the same frequency but prevents HIGH frequencies from going to the woofers. The HPF on you HU is to prevent LOW frequencies from going to your full-range speakers (or component set) and is usually set around 80-125Hz as stated before. THIS WON'T AFFECT the external xover that came with your speakers as one blocks low and the other blocks high. OK.. still with me? So far, nothing has overlapped as glass was saying. When I said the filters would add together I was talking about using a filter on your HU AND a filter on your AMP at the same time... but the external xovers that you speak of will not have any affect on these b/c they are for totally different frequencies (3K-5KHz) as opposed to the 80-125Hz on the HU and amp. let me know if any of that doesn't make sense. |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 8211 Registered: Dec-03 | dude, the slopes are not combined. your amp probably has a fixed slope of 18 or 24dB/octave, and that was the roll off you got. The head unit's slope and XO points are all digitally handled, not done using caps and chokes.. there isn't going to be any phase shift etc, and you're not going to get any interaction between the two if you set up the system properly. Ed, just do what I sugested initially before dude tried to overcomplicate things. use the head unit, or use teh amplifier for crossovers.. don't use both. once you choose which one you want to use, set them as suggested earlier. you're all done. period. should work fine |
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Silver Member Username: HellbenderLos Angeles, California USA Post Number: 123 Registered: Apr-05 | I would side with Glasswolf on this one. Just use one crossover and whichever one is easier or whichever that you prefer. |
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Bronze Member Username: CarletonPost Number: 11 Registered: Jun-05 | Thanks a lot guys, that really helped. I think I have a handle on it now, so when the amp comes, I'll know how to set it up. Again, thanks for the help. |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 8230 Registered: Dec-03 | if you want more info on slopes and XO settings, take a gander at www.bcae1.com lots of good info on crossovers and basics there good refrence site |
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Bronze Member Username: Dr_sharpUSA Post Number: 77 Registered: Jun-05 | "the slopes are not combined" yes they are. quit spreading bs and take a second to learn. Using a HU crossover (lets say LP) you will get something like -12dB/octave (40dB/decade) as you increase frequency. This is the input to the amp ALREADY FILTERED. Now, using a LPF on the amp set at the same frequency will further decrease the output by ANOTHER 12dB/octave. I realize that one is digital and one is analog.. that doesn't change the fact that the amps filter will still do its job. Why is that so hard to understand? You insist that I am wrong but you offer nothing but doubt... "dude YOU probably fucked up"... please correct me if I am mistaken and quit wasting my time by telling me i'm wrong with no explanation. |
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Silver Member Username: Riebread77Post Number: 297 Registered: Jun-05 | dude is correct...you can combine them...2 in-line crossovers 12 db/oct set at 100 hz will COMBINE to be 24 db/oct slope at 100 hz...however, it may not be ideal as you may see a phase shift...but if you can work out the phasing, more crossovers give you better control over frequencies that aren't supposed to be there (ex: a 4" coaxial...def does not want to see 40 hz and would do better with a little steeper slope than 18 or 24 db/oct) |
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Silver Member Username: Riebread77Post Number: 298 Registered: Jun-05 | you won't have a phase shift as long as it equals 24 db/oct...for every 6 db/oct after than until 48 db/oct, it is a 90 degree phase shift...that usually can be corrected on decent amps. |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 8250 Registered: Dec-03 | you won't have any phase shift period, because there isn't any with a digital process when everything is set prior to the DAC stage. As for combining the slopes, it's again NOT GOING TO HAPPEN because both crossovers shouldn't be set to THE SAME FREQUENCIES now instead of taking a moment to learn, try taking one to read. I stated that way back in this thread. and Ryan, more isn't better. you don't use two crossovers to increase the slope. you use one higher order filter instead. less crossover to send the signal through means less loss and lower end result distortion. don't overcomplicate things. it comes back to bite you in the rear. |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 8257 Registered: Dec-03 | wow I was in a bad mood this morning.. sorry about that. dentist appointment.. wasn't looking forward to it. heh |
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Silver Member Username: Riebread77Post Number: 308 Registered: Jun-05 | I your looking for extreme sound quality extra crossovers aren't a bad idea. It's obvious the slopes won't be the same frequency...signal loss is very minute for one extra crossover(especially if you only use 1.5' signal cables to connect them...but they will combine and change the signal strength...just making a point that the headunit's crossover will still affect the signal as well as the amps when you insisted it didn't |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 8275 Registered: Dec-03 | if one crossover is set beyond the range of the other crossover, you'll be at virtually 0dB by the time you get any effect from the second crossover. moot point. why use two 2nd order crossovers to get the same effect as a single 3rd order crossover though? it's pointless. especially when we have digital crossovers now with variable Q. They work much like having a parametric EQ in the digital realm. Much less loss and interference that way. |
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Bronze Member Username: Dr_sharpUSA Post Number: 78 Registered: Jun-05 | very true... but that still depends on the order of the filter. Example: a HPF @ 24dB/octave will reduce the signal so quickly that any filter more than an octave lower won't affect the audible sound. If, however, your talking about first order filters (6dB/octave) that are within an octave of eachother you will see some affects. Bode plots would be very handy here. but i have no software to show  |
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Bronze Member Username: Dr_sharpUSA Post Number: 79 Registered: Jun-05 | also, Glass I think you meant two 2nd order crossovers make a single 4TH order crossover. And you do that to have more control near the limits of the drivers frequency response. You can slowly decrease the signal as you approach the frequency you're after and then use the second filter to virtually cut the signal at the desired frequency. |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 8308 Registered: Dec-03 | yes fourth, thank you. I was looking at the diagram in my head, and not thinking about the actual order.. lol |
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Silver Member Username: Riebread77Post Number: 313 Registered: Jun-05 | agreed except for the part where only one octave will be effected by audible sound...take your speakers...set your hp x-over to 90hz w/ sub sonic filter off and w/ 24 db/oct...listen...then switch on the subsonic filter...2 octaves away...you will still hear a difference...thats why a second crossover could still be useful for much smaller speakers |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 8330 Registered: Dec-03 | you shouldn't be able to hear anything at 20Hz on a 6.5" midrange.. they naturally roll off above that point already.. but nice example theoretically speaking anyway |
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Bronze Member Username: Gpz1100Post Number: 33 Registered: Jul-05 | Good discussion on filters in the last few posts. Just want to clarify something. If you have 2 (two) 2nd order 100 Hz LP Filters cascaded (output from Filter 1 is the input for filter 2), would the final output not be attenuated at -24 dB/oct @ 100 Hz with no phase shift? Now, lets say you're using the LPF of your HU. Lets say it's also at 100 Hz with a -12 dB/oct roll off. On the amp you're using similar settings (LPF @ 100 Hz, -12 Db/oct). I realize both of these are doing the filtering in the digital domain (which should not affect phase), and that each filter may work slightly different, but wouldn't the final output be remotely close to a -24 dB slope? From the previous posts, this would not seem to be the case. Why? What would the final output be [close to]? |
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Silver Member Username: Riebread77Post Number: 378 Registered: Jun-05 | 1.) agreed...24 db/oct = 360 degrees = right back where you started = no phase shift 2.) The HU crossover does not affect phase shift because there isn't any with a digital process when everything is set prior to the DAC stage...so if you amp was set at 12 db/oct...you would see a 180 degree phase shift, not 360 degrees. |
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Bronze Member Username: Gpz1100Post Number: 35 Registered: Jul-05 | If the input to the amp has 0 deg shift, and the amp also works in the digital domain (or does it?), why the 180 deg shift (as compared to the original signal). What about the final output attentuation? |
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Bronze Member Username: Gpz1100Post Number: 37 Registered: Jul-05 | If this topic has already been discussed in depth in the past, can someone provide a link..? |
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Bronze Member Username: Gpz1100Post Number: 44 Registered: Jul-05 | Bump... glass we going to get your 2 cents on this? |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 8766 Registered: Dec-03 | depends on the amplifier entirely. geenrally, amplifiers don't handle EQing in a digitized format, pre-DAC. They handle that conventionally. Otherwise, the DACs would all be built into teh amplifiers, and we'd use TOSlink interconnects for a pure digital signal from headunit to amplifeir.. wouldn't that be dreamy. mainly I was just ignoring this thread.. it's getting really long and sorta started to turn into bickering over semantics. I didn't want that dragged out so I just let it go |
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Silver Member Username: Riebread77Post Number: 404 Registered: Jun-05 | Kicker SX amplifiers i believe have DSP and internal EQ...along with the ability to control EVERYTHING from your driver seat with a dash control...expensive amps. |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 8786 Registered: Dec-03 | they're class D. it's easier to manipulate the signal after sampling before it's reconstructed at the finels. class AB amps don't really have that luxury though, which is why I said it depends on the amplifier. |
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Silver Member Username: Riebread77Post Number: 413 Registered: Jun-05 | wow even the 700.4 and their smaller amps are class d?...didn't know that...good piece of info to know. |
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Gold Member Username: GlasswolfWisteria, Lane USA Post Number: 8796 Registered: Dec-03 | huh? I never said anything of the sort. most multi-channel amplifiers are class AB. If the class AB amplifiers have a DSP, they're running the signal through an ADC then back through a DAC again.. or they're class T amplifiers, which are like full range class D. if they are class AB, the DSP would probably just lose resolution of the signal.. I never liked going back and forth from analog to digital and back more times than absolutely needed. Every time you have to re-sample, and re-compile.. you lose signal resolution.. like compressing and recompressing an MP3 to WAV and back. |
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