Argh. What X-over to set my sub to? (my receiver sucks)

Discussion in 'Speakers & Subwoofers' started by MichaelDDD, Oct 2, 2003.

  1. MichaelDDD

    MichaelDDD Supporting Actor

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    I just got an email from Kenwood tech support. My VR-409 receiver has a FIXED 100Hz @ 24db/oct lowpass filter on the sub out. Nice slope, sucky frequency.

    This poses a filter-stacking dilemma. What do I set the crossover on my PB2+ at? IIRC, it's slope is 12db/oct which is not that steep.

    IIRC, a 24db filter + a 12db filter = a 36db filter which is 180 degrees out of phase. Am I right or just confused?

    Also, if the reciever sends a 100Hz lowpass, and I set the sub to 80Hz, what does that do for me/against me?

    I have my CV sub lowpass set at 80Hz and thought it sounded decent. But I'm stepping up in the world and want to ensure I'm good to go.

    Man, as time goes by and I learn a little more, I realize all the things my reciever is missing. The least of which is not an adjusable lowpass filter! Or at least a range of choices, i.e. 70, 80, 90, 100Hz. That would be nice.
     
  2. John Garcia

    John Garcia Executive Producer

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    Nothing wrong with a 100Hz x-over, though a lower one might work better depending on your setup. Your sub is not at issue here, since it should have no issue playing slightly above 100Hz. I would be more concerned about my other speakers and how this x-over point allows them to blend with the sub.

     
  3. MichaelDDD

    MichaelDDD Supporting Actor

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    Heh, there's no such thing as "too much sub." [​IMG] [​IMG] That's what gain controls are for; matching equipment.

    I'm a bass head so I'm happy with my purchase.

    The receiver will be upgraded in the future. Right now, I'm focusing on the speaker aspect of my rig. I'm just getting into "real" HT. I've been dealing w/B&M equipment for the 10+ years I've been into HT total due to money considerations.

    I remember reading words to the effect that if you take a signal crossed over at say 100Hz, then cross it over again at a lower frequency, you create a "shelf" which is not typically desireable, but can be blended in somehow.

    Thanks for your input though, John. [​IMG]
     
  4. ColinM

    ColinM Cinematographer

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    My HK AVR110 has the 100hz x-over, too. I happen to EQ the sub, so any blend issues are handled thay way.

    I will occasionally disconnect the EQ and then play with the sub's x-over, sometimes bringing it down to 70 or 80 (on the dial), and I like the effect.

    But I always go back to the EQ.

    Which brings up this - what's worse - the EQ in the chain or the 2nd crossover?
     
  5. Edward J M

    Edward J M Cinematographer

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    Your Kenwood BM circuit has a 12 dB/octave high pass filter, and a 24 dB/octave low pass filter.

    The high pass filter starts ramping down any surround channel set to small on a 12 dB/octave rate. So if you have a 100 Hz xo, at 50 Hz the surround speakers will be 12 dB down compared to the 100 Hz level. That's not counting the natural roll-off of the surround speaker itself.

    The low pass filter will start ramping down the subwoofer on a 24 dB/octave rate above 100 Hz. The filter slope for the low pass filter is much steeper because you really don't want the sub playing much information over 100 Hz because it can be too easily localized.

    So just set the filter switch to Disable on the PB2 and let the Kenwood BM circuit handle the rest and you'll be fine. While I prefer an 80 Hz xo, there is nothing wrong with a 100 Hz xo, particularly if your surround speakers are on the smaller side and are only rated down to 70-80 Hz for extension.

    Regards,

    Ed
     
  6. Keith M.

    Keith M. Second Unit

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    You can also use an inline low pass filter to essentially bring the receivers x-over lower than 100. This would help blend your front stage with the lfe better...
     
  7. MichaelDDD

    MichaelDDD Supporting Actor

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    Thanks Ed & Keith.

    100Hz is very high. I can easily pinpoint the location of the sub anywhere in the room.

    Shoot...I may wind up purchasing a new receiver...well, not really..don't have the cash for that too.

    Damn, this is getting expensive, FAST. [​IMG]




    My old CV sub doesn't have the ability to disable the X-over..so I just set it at 80Hz and forgot about it.

    I guess I will have to give your suggestion of disabling the PS2+s internal X-over a shot.

    I have a pretty decent stereo rig in my truck. I have my lowpass set at 70Hz/24db/oct, so I'm used to hearing or NOT hearing where the bass is coming from.

    I will have to try it out though, obviously.

    No one has explained the harm of stacking the two filters though. Someone care to educate the ignorant?
     
  8. John Garcia

    John Garcia Executive Producer

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    Localizing the sub can also be an effect of room placement. The best calibration still will not make up for the wrong placement. You may have to play around with it to find a spot that gives you what you are looking for.

     
  9. MichaelDDD

    MichaelDDD Supporting Actor

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    Thanks for the explanation, John.

    So, do you think even w/the 100Hz/24db-oct Xover point, I could still have a great sounding setup? Assuming I get good mains, of course!

    Right now, planning on either an Ascend CBM-170/370 combo or an Axiom M22ti/VP100 combo.

    I just wish there were some more reviews on the CBM170 out there...and of course the magical CM370s.
     
  10. John Garcia

    John Garcia Executive Producer

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    My old receiver had a fixed 100Hz x-over (Marantz SR6200). I had my reservations at first, but once it was setup and running, it sounded great. Now, my 8300 has a fixed 80Hz XO (THX std) and I can't really tell too much of a difference, though I am also using a new sub - HSU VTF2 with the xub's x-over bypassed.

     
  11. MichaelDDD

    MichaelDDD Supporting Actor

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    Yeah, combining the reviews I've read with my price range has narrowed it down pretty much to the M22s vs. CBM-170s...with possibly the ELT Rockets thrown in...that's more of a wildcard though.

    I've read that the M22s have a bright (not harsh), forward presence to them. I like that in my sound. I'm not much for the "classical music only with no treble to it background sound." Heh, I know what that means...though I doubt anyone else can follow my screwy thinking. [​IMG]

    I like "in your face" sound.

    Thanks for the help, John. [​IMG] It's good to hear that you had positive results with the same settings.
     
  12. John Garcia

    John Garcia Executive Producer

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    "Forward" is how I would describe the Axioms, but not in a bad way. They seem bright, brighter than my Monitor 5s were, but they are very detailed and are great for music. Vocals really shined.
     
  13. Lew Crippen

    Lew Crippen Executive Producer

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    You could try setting your speakers to ‘large’, so that the sub only produced the LFE channel.

    Of course this depend s on your speakers—certainly it would not be a good idea with the Ascend 170s or the ELTs.
     
  14. BenSC

    BenSC Stunt Coordinator

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    Where do you guys find out where the X-over is? My Sony STRDE675 (which hopefully will be replaced soon) appears to have a statix X-Over too. There is a "Bass frequency setting" that I thought was used as a frequency to redirect signals, but its really crazy, only going down to like 120 and going up to 500 or something like that.
     
  15. ColinM

    ColinM Cinematographer

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    Ben - That's your "corner" frequency for the bass tone control...pretty sure, anyway.
     
  16. Greg-ST

    Greg-ST Stunt Coordinator

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    I've got a Kenwood B&M receiver too (a bit newer than the 409.. it's actually the 615). Only thing it's really lacking is a sub pre-out which is a shame, but can still be worked around. Kenwood doesn't state the crossover in the manuals for some odd reason. I'm figuring it's probably a 100Hz crossover as well, but I'm not completely sure.
     
  17. MichaelDDD

    MichaelDDD Supporting Actor

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    Greg-ST, here's a link to Kenwood's Technical Support customer service.

    I have emailed them twice in the past week and got back an answer within 48 hours.

    You're right; my VR-409's manual doesn't list the X-over freq either. 100Hz is HIGH for a sub.

    What's odd is that the Kenwood is good receiver for it's price point...I wonder whey they cheaped out on the sub xover? At least they could've made it user-selectable with like three freqs or something. 70/80/90 Hz would've been perfect.
     
  18. John Garcia

    John Garcia Executive Producer

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    Usually you won't see 70-80-90, because there is almost no difference between them. You will see something more like 80-100-120 or user selectable.
     
  19. MichaelDDD

    MichaelDDD Supporting Actor

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  20. John Garcia

    John Garcia Executive Producer

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    Check around. I can almost guarantee, not only will you not find a receiver with a selectable 70Hz x-over, you will find it difficult to locate a significant number of manufacturers who even give you a selectable x-over, especially in the $400 and under price range. I consider my receiver to be pretty decent, and it does not give me a choice. I have large or small, small being THX fixed at 80Hz.

    Sony offers the most flexible I've seen - user selectable per channel. H/K is next with it's "triple x-over", which allows 60-80-100-120 (I believe), depending on settings.

    8" and 10" drivers are less accurate at reproducing midrange - trying to do too many things at once. Small drivers that focus on a smaller range do a better job at what they are trying to do. Let the big drivers do what they are supposed to do - bass.

    I've been into car audio just as long, and home audio for about 10+ yrs.

    70Hz vs 80Hz in a typical sized room is not that much different, probably barely audible, but in a car, there can be a big difference. Two very different environments though.
     

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