High passed, something wrong, or really that hard to drive?

JimAckley
JimAckley Posts: 1,138
edited March 2011 in Speakers
In the middle of my free time today, I decided I would swap from my LSi25s to my LSi7s on my main HT. Just for kicks, I hooked one of each to my 2-channel system, and was kind of surprised at what I saw.

Is the LSi25's HF section highpassed because of the 10" woofer integrated into the side? Or do you think something is wrong? Or is the LSi7 really insanely much easier to drive than the LSi25? I figured I'd get at least half the excursion per cone as I do from the 7s, but it's as if the 25s weren't even hooked up.

On a side note, despite having the subwoofer from the 25 hooked up and set to its highest crossover point, the midbass is slightly punchier in the 7s. The mids seem a little hotter in the 25 than in the 7, which I suppose I can attribute to the extra midrange/midbass driver.

Back to the topic at hand:

My first guess is that the HK doesn't have enough oomph to drive the LSi25s, but I didn't expect it to be that bad. In fact, I remember my Kenwood VR-9070 got those midrange/midbass drivers moving a noticeable amount when I was using it as my receiver. I'll try my Pio on full range, and try my kenwood for kicks, but it'll have to be later tonight, since I have to go to work in a few minutes. My second guess is that it's at least partly due to crossover design, but I'm no electrical engineer, so I'm not sure.

I included a video so you can see what I'm talking about. Again, for clarification, these are being driven by my HK 3480, no equalization whatsoever. The LSi25 is hooked up to my left channel and my LSi7 is hooked up to the right channel, balance set to equal, like always.

http://www.youtube.com/watch?v=vBibMeFozDM
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Post edited by JimAckley on
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Comments

  • rooftop59
    rooftop59 Posts: 7,952
    edited February 2011
    Well others will know better, but I know that according to the stereophile bench test the 7s are really more like 6 ohm speakers that dip into 4 ohms, while the 9s and on up are true 4 ohm speakers that dip below 2 ohms at certain points. I drive my 7s which a similarly powered hk and think they sound great, and have purposely never tried the 9s because I know I can't afford the power.
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  • JimAckley
    JimAckley Posts: 1,138
    edited February 2011
    I'm guessing their impedance is dipping low and the amplifier is limiting its current so it won't cook then... So much for using the HK and LSi25s as a 2-ch system!
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  • JimAckley
    JimAckley Posts: 1,138
    edited March 2011
    Just giving an update, I put them both in my bedroom and am currently using the HK to power them. It sounds decent, but I can definitely feel it struggling. Once my volume passes -19dB I can hear it starting to limit itself, whereas the LSi7 would make it to -12dB and the speaker would reach its limitations, but I feel that would again be remedied by a crossover. I used to have a Rane external but sold it years back. What I would give to have it for these tests...

    In a bit I'm going go flip the Kenwood 9070 in and see how that goes. At least it let's me use a crossover so I don't have to attempt to drive them full-range.
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  • Face
    Face Posts: 14,340
    edited March 2011
    JimAckley wrote: »
    I'm guessing their impedance is dipping low and the amplifier is limiting its current so it won't cook then... So much for using the HK and LSi25s as a 2-ch system!
    IIRC, the 25's dip down to 3ohms. If you attempt to listen loud enough, you'll destroy your tweeters and possible some crossover components.
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  • JimAckley
    JimAckley Posts: 1,138
    edited March 2011
    Yesterday I took it into distortion once (occurs around -13dB on my HK), only for a brief second, just to find the limit and haven't gone anywhere close to it since, primarily keeping it at -30dB since that's more than enough to fill my room. None of my tweeters are blown, and I'm going to redo those darned crossovers in the next couple months anyway.

    The funny thing about when I get it to -19dB is that it sounds like the bass is limiting itself, but there's no clipping. It's not really much of an issue since I'll never be playing it that loud anyway.
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  • Face
    Face Posts: 14,340
    edited March 2011
    The longer you wait on buying an amp, the longer you're risking damage to those speakers. Think of it this way, when you destroy a pair of tweeters, it'll be like adding $100+ to the price of the amp.
    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
  • JimAckley
    JimAckley Posts: 1,138
    edited March 2011
    I'm only using them in my 2-ch long enough to see how my 7s sound in my HT. This is by no means a permanent thing. And As long as I don't crank it, I should be okay, correct?
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  • BeefJerky
    BeefJerky Posts: 1,319
    edited March 2011
    When it sounds "like the bass is limiting itself," you are overdriving the amplifier. It may not sound like clipping to you, but the amplifier is being driven into clipping. As others said, you are seriously risking damage to the speakers.
  • aboroth00
    aboroth00 Posts: 1,103
    edited March 2011
    Did you level match the speakers using a SPL meter? Seeing it or perceiving to play louder is very different than actual SPL levels.

    Clipping the amplifier into the bass driver is not good but it's certainly not as bad as clipping the tweeter. Clipping the bass gives you a hint before you start to clip the tweeter as to turn it down.

    As for dipping below 2 ohms or even to 2 ohms, I REALLY doubt it. If it dips to 2 ohms, most amplifiers would crap themselves and turn off or fry. Seeing you have a HK receiver running this at moderate levels, the speakers definitely do not dip to 2 ohms. So don't go looking for a 2 ohm stable amplifier; those are hard to come by for cheap.
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  • JimAckley
    JimAckley Posts: 1,138
    edited March 2011
    Just a fun little FYI:

    When you've had these big LSi25s as your fronts in your HT for four years, and you swap them out to little LSi7s on stands, it looks really goofy haha.
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  • JimAckley
    JimAckley Posts: 1,138
    edited March 2011
    Just a few minutes ago, I switched out the HK for my Kenwood VR-9070, and must say the change is QUITE noticable. The quality of sound was increased so much by using the crossover. This thing is also quite a bit heavier than the HK. I realize that's in part because it's a 7-channel receiver, but the midbass is quite a bit punchier than it was with the HK. Highs don't seem to be any different. If anything, a hair brighter than the HK, but we're not talking levels of brightness like RTis powered by Yamahas.

    I've used that Kenwood on the LSi25s almost the whole time I've had them (exceptions being when I still had my Crown XS900, and when we were remodeling our house and I had the X1's components upstairs), and I just remembered why. It can handle them. It doesn't make them generate the SPL levels that would be enjoyable from a high powered amplifier, but it doesn't choke down and it doesn't distort. The only downfall is the display on the unit is failing, and it doesn't have an OSD. But all you have to do is hit it on the top like The Fonz and it comes back on :biggrin:
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  • cnh
    cnh Posts: 13,284
    edited March 2011
    I'm not surprised the HK can't handle the towers. I like mine fine with the LSI-7s but I've recently added a mere 100 watt/channel power amp to the HK and the LSI-7s sound even better with the HK as a pre?

    I do find it a little hard to believe that a 500 dollar 6.1 Kenwood AVR has more power in 2 channel than an HK?

    Which HK do you have the 33xx or the 34xx series. I have the 3490?

    I also own an ancient Kenwood Dolby pro-logic AVR that weighs quite a bit more than the 9070? It's only a 4 channel, the L/R are a TRUE 130 watts/channel. The rears a mere 20 watts? But the power draw on the back is 5 AMPS or 600 watts. The old-timer can also run 4 ohm loads without much of a sweat. It's basically a two channel amp with a smaller 2 rear channel section for Pro-logic rears. I've never been able to get the volume knob past 50 percent without sending everyone out of the room. lol

    cnh
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  • JimAckley
    JimAckley Posts: 1,138
    edited March 2011
    7.1 sir :tongue: 9070 is a 7 channel unit.

    I think the difference maker is the fact that I now have a crossover in use. The amplifier is freed up from everything < 80Hz and can focus on what the speakers are designed for in the first place.

    My HK is the 3480. Should be about 150w @ 4ohms, right? The HK got louder than the Kenwood, but went into distortion after moderate volumes. The Kenwood delivered a lot more oomph and punch in the midbass, and never seems to go into distortion, but it can only generate moderate volumes. Nothing of a movie-theater caliber. I dunno... I'm not a pro at this stuff, but when I switched to the Kenwood and turned the Inception soundtrack back on, I could feel the midbass hitting me right in the chest at the end of "528491". I hadn't felt anything like that from my HK.

    I'll hook the Kenwood's pre-outs to the HK's amplifier-ins later and see how that goes. That should tell me pretty quick which amplifier does a better job driving them cleanly.

    P.S. - now you've got me wanting to try my old-school NEC 4-ch receiver. I used to run subwoofers with it. It's 2 2-channels, just like yours.
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  • BeefJerky
    BeefJerky Posts: 1,319
    edited March 2011
    And, speaking of which, your video showing the LSi7's driver moving more than the LSi15 means nothing. The LSi7's driver you are focusing on has to handle all the bass frequencies, whereas the LSi15's driver doesn't since they are redirected to the 10" woofer. So, of course the LSi7's mid/bass driver will be moving more than the LSi15's.
  • JimAckley
    JimAckley Posts: 1,138
    edited March 2011
    The LSi25 has its own powered woofer, completely independant from the HF circuit.

    If you're thinking of the LSi15, it has an 8" woofer.

    However, we're talking about the 25 here.
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  • aboroth00
    aboroth00 Posts: 1,103
    edited March 2011
    JimAckley wrote: »
    The LSi25 has its own powered woofer, completely independant from the HF circuit.

    If you're thinking of the LSi15, it has an 8" woofer.

    However, we're talking about the 25 here.

    I don't quite understand what's being accomplished here. If the speakers are run full range, yes most of the bass is being redirected to the bass driver in the Lsi25. The driver on the 7 is handling all the frequencies and must exert more effort to deal the same amount of volume.

    If you really want to know whether the speakers are hard to drive, just look at the impedance curves of each respective speaker. As for looking at how much the speaker moves, it's certainly not scientific, just fun to do.

    Try watching the WOTW pod emergence scene, that'll make your speakers move.
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  • BeefJerky
    BeefJerky Posts: 1,319
    edited March 2011
    JimAckley wrote: »
    The LSi25 has its own powered woofer, completely independant from the HF circuit.

    If you're thinking of the LSi15, it has an 8" woofer.

    However, we're talking about the 25 here.
    You are correct, my bad. However, what I said is still applicable. The mid drivers in the LSi25 have a high pass filter at 80hz, so the lower bass frequencies won't get sent to those drivers. The LSi7's don't have a low-pass filter on the mid/bass driver, so those frequencies make it to the driver. That is what makes the LSi7's driver move so much more in the video you took.

    I've also been thinking about the "bass sounds like it's limiting itself" thing on the LSi25's, that really is weird. I don't see how your receiver's power would even have anything to do with this since those frequencies are being driven by the internal amplifier. Or, are you talking more about the mid-bass frequencies that would be driven by the two mid/bass drivers?

    Either way, as others have said, the LSi9/15/25 all use two mid/bass drivers, so that would make it harder for your amp to drive. Apparently the speaker system also ends up with a lower impedance due to the two drivers. This would put more strain on the current capability of your amplifier, which could explain the issue as well.

    I know you mentioned doing a test with the HK fed from the Kenwood's high passed output. I'd also be interested in how the Kenwood handled the LSi25's with the crossover turned off and driving them full range.
  • TNRabbit
    TNRabbit Posts: 2,168
    edited March 2011
    BeefJerky wrote: »
    When it sounds "like the bass is limiting itself," you are overdriving the amplifier. It may not sound like clipping to you, but the amplifier is being driven into clipping. As others said, you are seriously risking damage to the speakers.

    Sounds like compression to me...a clear indicator of over-driving an amp.
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  • Face
    Face Posts: 14,340
    edited March 2011
    I feel like a broken record, but you need an amp.
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  • JimAckley
    JimAckley Posts: 1,138
    edited March 2011
    I just bought new receiver, and the gas prices are gonna limit my expansion if they keep going up. I feel like a broken record, but this whole thing is just a temporary setup while I do some testing on my HT. If this were a permanent thing, I'd be looking into some separates, but considering this isn't a permanent thing, and I don't have money to spare right now, I'm not getting an amp.. I was just curious by the differences in the way the two speakers performed. I'm not trying to get advice on a new system. Just sharing some things I've noticed, and getting some questions answered.

    In regards to the HK, the weird thing about it, is that the bass is being supplied to the LSi25s via line-level cables, not even through the speaker lines, and it's being compressed. My apologies for neglecting to mention that earlier.

    The real reason for the drivers not having the excursion of the LSi7 is the 500uf capacitor in the LF circuit, so I was right in one of my first guesses that it was a high-pass thing. The LSi25s aren't super hard to drive if you're okay with moderate volumes being the highest you can achieve clearly. You do absolutely need an amplifier for higher volumes though.

    Consider this case closed.
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  • JimAckley
    JimAckley Posts: 1,138
    edited March 2011
    Just for closure sake as well as my never ending curiosity, I finally did the test.

    For the test, I used my Signal Cable interconnects and ran from the Kenwood's pre-outs into the HK's amplifier-ins. I initially left the crossover active at 80Hz, and first ran the Kenwood alone, then flipped the right channel to the HK, then both to the HK. I then repeated these just a moment ago with the Kenwood set to fullrange. What I discovered was interesting...

    At first I was thinking "Wow, is my Kenwood really beating the HK?" And at first, that answer was a yes. Then it became, yes, as long as the crossover is active. Without the crossover in place, the Kenwood's amplifier will trip itself at -12dB, whereas the HK can play right on through to +3dB. Remember how I was telling you about bass limiting itself, distortion, etc earlier? That was a big thank you to the HKs preamplifier section. There was ZERO compression, and ZERO distortion when using the Kenwood as a pre. So it wasn't the amplifier dealing me fits all along.

    Something notable though: just like my assessments of the individual units earlier in the thread, the HK unit has a little less midbass thump. You can barely tell, the difference, but it's enough to be perceivable. I haven't measured it with any equipment yet, and intend to get around to that at some point.

    For you number crunchers out there, there are no published ratings for the Kenwood at 4Ω. However, it's rated for either 100w or 110w at 8Ω, but I can't remember specifically which it is. The HK is rated for 120w @ 8Ω, 150 at 4Ω.

    My final assessment: There's no question that an amplifier capable of a stable 250-300w RMS @ 4Ω would be beneficial, but not absolutely necessary to produce enjoyable volumes from this speaker set.
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  • JimAckley
    JimAckley Posts: 1,138
    edited March 2011
    On another thought, maybe the HK's amplifier was distorting when I ran it earlier. The fact that it never did when the pre was swapped is what has me convinced it was the pre. You pros who've dealt with this stuff, tell me if I'm wrong.
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  • aboroth00
    aboroth00 Posts: 1,103
    edited March 2011
    You HAVE to do spl tests with a SPL meter. You cannot compare to volume levels on two different receivers and assume they put on the same SPL.

    The volume knob is a relative meter. +3 is not necessarily the same as +3 on any other receiver. All it tells you is that at +13 relative to +3 is that it's driving twice the power with twice the volume.
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  • JimAckley
    JimAckley Posts: 1,138
    edited March 2011
    aboroth00 wrote: »
    You HAVE to do spl tests with a SPL meter. You cannot compare to volume levels on two different receivers and assume they put on the same SPL.

    The volume knob is a relative meter. +3 is not necessarily the same as +3 on any other receiver. All it tells you is that at +13 relative to +3 is that it's driving twice the power with twice the volume.

    Okay, what would you like me to meter? I can't seem to figure out what angles I didn't cover here.
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  • aboroth00
    aboroth00 Posts: 1,103
    edited March 2011
    You're trying to compare how well each amplifier performs and how loud each speaker gets before clipping.

    You need to measure how loud each speaker is on each amplifier with a SPL meter. The volume read out on the receivers tell you nothinga bout how loud it gets. So you need to measure each amplifier's respective loudness when you start hearing clipping.

    If you did not use a SPL meter in the original tests, then you've concluded nothing.
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  • JimAckley
    JimAckley Posts: 1,138
    edited March 2011
    Because once I switched preamps, I didn't get to distortion before it would just simply hurt my ears. I'm not testing beyond that for you. In full range, the Kenwood simply goes into protection before it gets to clip. The HK rides it out to full volume. When crossed, they can make it to the same point. The volume between the two is not any different. At least nothing that was perceivable while I was running a channel from each unit at the same time. I'll meter it tomorrow though.
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  • jjk_reef00
    jjk_reef00 Posts: 23
    edited March 2011
    Great information here. I've always been a fan of high power amps. It will interesting to see what your reading show.
  • thesurfer
    thesurfer Posts: 574
    edited March 2011
    JimAckley wrote: »
    Because once I switched preamps, I didn't get to distortion before it would just simply hurt my ears. I'm not testing beyond that for you. In full range, the Kenwood simply goes into protection before it gets to clip. The HK rides it out to full volume. When crossed, they can make it to the same point. The volume between the two is not any different. At least nothing that was perceivable while I was running a channel from each unit at the same time. I'll meter it tomorrow though.
    H/K is a better unit than kenwood,,, all the way around,,, Kenwood was always a entry level reciever maker,, at least when i got one, years ago,
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  • stewbaca
    stewbaca Posts: 10
    edited March 2011
    My HK took three rounds to get one that functions properly sonicaly, the video processing was awful....sound is primo though for an all in one..AVR745
  • thesurfer
    thesurfer Posts: 574
    edited March 2011
    stewbaca wrote: »
    My HK took three rounds to get one that functions properly sonicaly, the video processing was awful....sound is primo though for an all in one..AVR745
    Like anything though,you want the Full show, ya gotta pay the big dough,,
    Not an Audiophile, just a dude who loves music, and decent gear to hear it with.