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Thread: In-line high-pass filter

  1. #1
    Senior Member MikeBrewster77's Avatar
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    In-line high-pass filter

    Greetings,

    Does anyone have any experience using an in-line high-pass filter for their main speakers when coupled with a sub? I have a decent sub with solid response to 120hz, and am about to purchase a set of JBL L46's (this system is in a small room, so larger speakers would likely overpower the space.) If I recall correctly the L46's start to bottom out around 70hz, and I'd like to free them up a bit so they're not struggling with the lower frequencies. I'm thinking of a high-pass filter with a cross-over of 100hz. Given what I'm working with, an active cross-over & multiple amps is not really the route I want to go, and as a bit of a stereo purist (unlike the A/V receivers out there) my current amp doesn't offer the ability to control cross-over. The sub has a variable filter, so my thought was use a high-filter pass to cut the mains at 100hz, and set the sub accordingly.

    Any suggestions? I guess I could alter the stock cross-over in the L46's, but again, that's a path I'd prefer not to go down.

    I've seen a lot of "in-line" passes for car audio, but nothing for home systems. Any advice would be greatly appreciated! Also, are there any potential negative side-effects from this arrangement?

    Thank you in advance.

    P.S., If anyone is aware of a stereo integrated amp that does have subwoofer crossover control, I'd be interested in hearing about that as well.

    Best,
    - Mike

  2. #2
    Senior Member Fred Sanford's Avatar
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    I'm using Harrison F-Mods in a similar way, as a passive line-level low-pass for a sub I'm using under some L110s. At only ~$30/pr from Crutchfield, it was easy to justify testing them out. For your purposes, I'd think they would work just fine.

    I have my L46s high-passed at 100Hz as well, but with an Adcom A/V preamp and an HK processor. Works well, and gives me a little more confidence since the power amp I'm using with them is only 60WPC.

    http://www.crutchfield.com/p_0699000...ml?search=fmod

    je

  3. #3
    Senior Member MikeBrewster77's Avatar
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    Thanks Fred - glad I'm not the only one out there with this "crazy" idea, and good to hear that it's working out well for you! I'll check them out.

    Update - I did check them out, and while I can see where (with the RCA jack input/output confguration) they'd work well with a sub configuration as a low-pass solution, not sure how I'd use these as a high-pass in line with standard speaker wire. Any thoughts? Is anyone aware of anything on the market that would take actual amp's speaker output and achieve the same effect. Again, I'm trying to avoid bi-amping anything with this particular set up.

    Fred, I looked at some H/K processors (specifically the 2.0) that have a cutoff of 100hz, but is that two way - i.e., does it cut at 100hz down to the sub and 100hz+ to the mains?

    Thanks again for your help/ Mike

    Quote Originally Posted by Fred Sanford View Post
    I'm using Harrison F-Mods in a similar way, as a passive line-level low-pass for a sub I'm using under some L110s. At only ~$30/pr from Crutchfield, it was easy to justify testing them out. For your purposes, I'd think they would work just fine.

    I have my L46s high-passed at 100Hz as well, but with an Adcom A/V preamp and an HK processor. Works well, and gives me a little more confidence since the power amp I'm using with them is only 60WPC.

    http://www.crutchfield.com/p_0699000...ml?search=fmod

    je

  4. #4
    Senior Member Fred Sanford's Avatar
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    Quote Originally Posted by MikeBrewster77 View Post
    Thanks Fred - glad I'm not the only one out there with this "crazy" idea, and good to hear that it's working out well for you! I'll check them out.

    Update - I did check them out, and while I can see where (with the RCA jack input/output confguration) they'd work well with a sub configuration as a low-pass solution, not sure how I'd use these as a high-pass in line with standard speaker wire. Any thoughts? Is anyone aware of anything on the market that would take actual amp's speaker output and achieve the same effect. Again, I'm trying to avoid bi-amping anything with this particular set up.

    Fred, I looked at some H/K processors (specifically the 2.0) that have a cutoff of 100hz, but is that two way - i.e., does it cut at 100hz down to the sub and 100hz+ to the mains?

    Thanks again for your help/ Mike
    I should have mentioned that I use them before a power amp, then feeding a passive sub. This particular product is line-level, I wasn't sure what your setup was or what your potential options could be (pre-out/power amp in, etc.). Yes, there are passive high-pass options for speaker level, but (as mentioned) line level has the added benefit of reducing the working load of your mains amplifier. Check out Crutchfield and Parts Express for what is out on the market...not that they're the only or the best places to buy, but they'll let you wander around and usually have decent descriptions. In fact, you can employ the Crutchfield customer service folks, they're not bad at all - an auto-based trick may be perfect for this application.

    What's your current system? If it's a receiver or integrated amp, does it have a pre/power patch option?

    Yes, generally if a processor has a sub out with low-pass filter, it will have (at least a menu option for) high-pass filter as well. You'll often see these in the manual as "speaker type small/large" and "bass management sub/main/both" or similar wording.

    je

    Edit: by the way, you have an active sub... so you are already bi-amping. Does your sub have ins AND outs? Do they have a high-pass in line? What's that model #?

  5. #5
    Senior Member MikeBrewster77's Avatar
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    Hi Fred:

    I truly appreciate your response.

    I'm running a Yamaha RX-797 receiver with a line-level RCA sub output to a Mirage active subwoofer. I use the line level output to the sub rather than using it in a passive arrangement because I presumed a passive set-up would rob the receiver of power (it’s rated at 100 X 2 @ 8 Ohms.) I have the sub crossed at around 70hz right now, but am trying to get a clean cross over and also relieve my bookshelves from reproducing more low-end bass than they need to (sorry for ending my sentence with a preposition, but it seemed a bit too complicated to re-architect it to be grammatically correct...)

    I never conceptualized it the way you described it, but you’re right in that I am bi-amping the system by using the receiver in conjunction with the sub’s amp. The receiver does have pre/power patch capabilities.

    In short, what I’m trying to accomplish is a passive (speaker-level) cross over to the mains, and I can pretty much deal with the sub accordingly using the built in cross over or the RCA in-line low pass option you shared earlier. Essentially, what I’m trying to avoid in my current state – as unrefined as it may sound – is having more than one amp in my rack to deal with this.

    I’d definitely appreciate your advice.

    Best,
    - Mike

  6. #6
    Senior Member Fred Sanford's Avatar
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    Quote Originally Posted by MikeBrewster77 View Post
    Hi Fred:

    I truly appreciate your response.

    I'm running a Yamaha RX-797 receiver with a line-level RCA sub output to a Mirage active subwoofer. I use the line level output to the sub rather than using it in a passive arrangement because I presumed a passive set-up would rob the receiver of power (it’s rated at 100 X 2 @ 8 Ohms.) I have the sub crossed at around 70hz right now, but am trying to get a clean cross over and also relieve my bookshelves from reproducing more low-end bass than they need to (sorry for ending my sentence with a preposition, but it seemed a bit too complicated to re-architect it to be grammatically correct...)

    I never conceptualized it the way you described it, but you’re right in that I am bi-amping the system by using the receiver in conjunction with the sub’s amp. The receiver does have pre/power patch capabilities.

    In short, what I’m trying to accomplish is a passive (speaker-level) cross over to the mains, and I can pretty much deal with the sub accordingly using the built in cross over or the RCA in-line low pass option you shared earlier. Essentially, what I’m trying to avoid in my current state – as unrefined as it may sound – is having more than one amp in my rack to deal with this.

    I’d definitely appreciate your advice.

    Best,
    - Mike
    If I'm following correctly, you'll need to determine whether your Yamaha has pre-out/power-in patch capability, and you'd use two RCA y-jacks (double male, single female) to go out the pre-out, feed the sub amp from the female RCAs, and plug the y-jacks back in through the two high-pass FMODs so the Yamaha amp is relieved of reproducing the low freqs.

    je

  7. #7
    Senior Member grumpy's Avatar
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    This isn't as hard as all that... if F-mods are used, just put them in the "coupler"
    main-in/pre-out loop.

    Sub line-out is separate.

    http://www.crutchfield.com/App/Produ...2RX797&g=10420

    (zoom in on rear panel)

  8. #8
    Senior Member Fred Sanford's Avatar
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    Quote Originally Posted by grumpy View Post
    This isn't as hard as all that... if F-mods are used, just put them in the "coupler"
    main-in/pre-out loop.

    Sub line-out is separate.

    http://www.crutchfield.com/App/Produ...2RX797&g=10420

    (zoom in on rear panel)
    I wasn't sure if the RX series had a dedicated sub out, I knew the RX-V's did. If it has a sub out, wouldn't it have bass management that could be set up to remove the bass freqs from the main amps, eliminating the need for FMODS?

    je

  9. #9
    Senior Member MikeBrewster77's Avatar
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    Fred and Grumpy thank you both for your advice.

    After reading your suggestions, it made me realize just how much I had overcomplicated what is a really a very easy setup.

    Thanks again!
    - Mike

  10. #10
    Senior Member MikeBrewster77's Avatar
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    One would think, but there is no cross over control or other bass management options on the receiver. From what I've heard in talking to some folks in the audio world, for some reason pure stereo receivers simply don't have this feature, unlike A/V receivers which almost universally do these days.

    Nonetheless, the sub does have a cross over control so I can simply use that to manage how it performs. My main concern was eliminating the redundancy of bass reproduction in the mains, so using the F-mods in loop seems like the easiest way to go.

    Quote Originally Posted by Fred Sanford View Post
    I wasn't sure if the RX series had a dedicated sub out, I knew the RX-V's did. If it has a sub out, wouldn't it have bass management that could be set up to remove the bass freqs from the main amps, eliminating the need for FMODS?

    je

  11. #11
    Senior Member Fred Sanford's Avatar
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    Quote Originally Posted by MikeBrewster77 View Post
    One would think, but there is no cross over control or other bass management options on the receiver. From what I've heard in talking to some folks in the audio world, for some reason pure stereo receivers simply don't have this feature, unlike A/V receivers which almost universally do these days.

    Nonetheless, the sub does have a cross over control so I can simply use that to manage how it performs. My main concern was eliminating the redundancy of bass reproduction in the mains, so using the F-mods in loop seems like the easiest way to go.
    Sounds right, then...

    je

  12. #12
    Senior Member MikeBrewster77's Avatar
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    Unless, of course, I can convince myself that I need one of these:

    http://www.outlawaudio.com/products/rr2150.html

    To my knowledge and based upon my research, the only stereo receiver that has integrated bass management controls. For the price point, it got some pretty good reviews too.

    http://www.stereophile.com/integratedamps/306outlaw/

    Hmmmmmm..............

    Quote Originally Posted by Fred Sanford View Post
    Sounds right, then...

    je

  13. #13
    Senior Member Fred Sanford's Avatar
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    Quote Originally Posted by MikeBrewster77 View Post
    Unless, of course, I can convince myself that I need one of these:

    http://www.outlawaudio.com/products/rr2150.html

    To my knowledge and based upon my research, the only stereo receiver that has integrated bass management controls. For the price point, it got some pretty good reviews too.

    http://www.stereophile.com/integratedamps/306outlaw/

    Hmmmmmm..............
    Hmmm...$30 invisible toys that get installed and forgotten and you can't really hear them, or $700 new toy that's visible and purty and shiny and you get to touch and hear it all the time...hmmmmmm...that's a tough one, you should ask somebody else!

    Are you the guy that bought Yank's L46s? I also considered plugging the ports on them when using them with a high-pass filter & sub, but never heard any corroborating "go for it" kind of advice from others here. I figured it might tighten things up a bit, and maybe protect them somewhat (I use them in a theater environment) from peaks (such as dropping a needle on a record?).

    je

  14. #14
    Senior Member MikeBrewster77's Avatar
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    I know - tough call, right? Hmmm - something tangible, fun, and unique, or a couple of hidden filters... This would generally be a no brainer if it weren't for the @#$%&!+ economy scaring the bejeesus out of me these days.

    I am the lucky guy who snagged Yank's L46s. That being said, I guess I'm not so scared of the economy that I've gone into hunker down in the bomb shelter, full out preservation financial mode yet; truth be told, I don't even have a bomb shelter - that would be weird, and I bet they have crappy acoustics.

    I've read varying opinions on plugging the ports (not necessarily specific to the L46, but on other models) some of which are good, some indifferent, but none particularly negative. It's something I may try once I get everything balanced to see what the sound impact is. Not particularly worried about peaks (the cueing lever on your turntable is your friend ) but you make a good point, and accidents do unfortunately happen.

    - Mike

    Quote Originally Posted by Fred Sanford View Post
    Hmmm...$30 invisible toys that get installed and forgotten and you can't really hear them, or $700 new toy that's visible and purty and shiny and you get to touch and hear it all the time...hmmmmmm...that's a tough one, you should ask somebody else!

    Are you the guy that bought Yank's L46s? I also considered plugging the ports on them when using them with a high-pass filter & sub, but never heard any corroborating "go for it" kind of advice from others here. I figured it might tighten things up a bit, and maybe protect them somewhat (I use them in a theater environment) from peaks (such as dropping a needle on a record?).

    je

  15. #15
    Senior Member Fred Sanford's Avatar
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    Quote Originally Posted by MikeBrewster77 View Post
    I know - tough call, right? Hmmm - something tangible, fun, and unique, or a couple of hidden filters... This would generally be a no brainer if it weren't for the @#$%&!+ economy scaring the bejeesus out of me these days.

    I am the lucky guy who snagged Yank's L46s. That being said, I guess I'm not so scared of the economy that I've gone into hunker down in the bomb shelter, full out preservation financial mode yet; truth be told, I don't even have a bomb shelter - that would be weird, and I bet they have crappy acoustics.

    I've read varying opinions on plugging the ports (not necessarily specific to the L46, but on other models) some of which are good, some indifferent, but none particularly negative. It's something I may try once I get everything balanced to see what the sound impact is. Not particularly worried about peaks (the cueing lever on your turntable is your friend ) but you make a good point, and accidents do unfortunately happen.

    - Mike
    Right - we don't have to get off on that tangent here, but it is somewhat apropos. There's no known bass hump that we're trying to knock down in the L46 (as opposed to the L100 where plugging the port actually brings response closer to flat). I also don't assume that the foam-edged L46 woof is happier overall in a closed box - my initial question was whether plugging the port may help by limiting excursion in this situation, which is likely one not considered by the design engineers (high-pass filter in place, a sub picking up the slack). Also, modern movie soundtracks are probably potentially more dynamic and punishing than music of the L46's time period.

    je

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