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Discussion Starter #1
My old Velo ULD 15a is being fixed (again) and while waiting for a new VMPS Larger to replace it, I have been listening to music (not movies) for the first time with just my main speakers and it sounds damn good- BETTER than with the Velo.


Why? Dunno. Perhaps I've never been able to match the crossover between my sub and speakers properly.


Or, I have B&W 801 mkIII's and recently bi-amped with Crown K2 on the woofers (12") and Krell KAV-250a. Thats a very powerful amp on reasonably sized drivers.


I'm going to do freq. curve tonight but the sq subjectively is tight(er), extended and clean(er) sounding at 95db or so.


Makes me believe that matching mains and a sub is more critical than I thought. My speakers are probably fine to 20Hz or so so its really sub-20Hz that needs reinforcing for occassional music and movies. The Velodyne was probably just a redundancy for the most part- and worse- imparted multiple x-overs, distortion etc . on the music.


When I considered a new sub(s) I pre-concluded (thats not a real word) that only a really deep sub ought to be considered and this recent experience tells me I may be correct.


YMMV
 

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If I had speakers truly good to 20hz, I'd listen to music without my sub as well...


Heck at that point, even HT would only be marginally increased by adding a sub as long as you can get the LFE to the mains.
 

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I plan on crossing my mains over around 40Hz. I've been researching subs in the 15" and 18" range since they'll essentially be running between 15Hz-40Hz. Currently, it appears that the goals I have set well best be achieved via the DIY route. I prefer a sealed enclosure, and the top two "off-the-shelf" contenders I have penciled in are ACI (Maestro), and Velodyne (DD15/DD18). I'm not sure if a pair of Maestros will be sufficient, and the wife has already vetoed either pair of the Velos (6k-8k). I'm going to try and exercise patience to see what drivers are rolled out over the next 90 days.


Rumor has it that Bosso is working on something; with him in the design loop the product has to be good!


Now where is that Bosso anyhow???


Regards,


Larry
 

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While what you say is very true, its probably because you crossed your speakers way too high into the subwoofer. My N805's are good to 40hz in my room, so my subwoofer comes in below them at 35hz (the minimum setting on my subwoofer). The music sounds great without the sub, but better with the sub on pieces that emphasize the lower octave. Movies are much better with the sub.
 

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The B&W web site specs on the MK3's show their effective range to 32 Hz. I only say that because my RF-7's have the same rating. I too was subwooferless for a time and ran my mains as large. Music was very good. Movies were alltogether another story. The 15 to 32 Hz range I was missing was substantial. You can't pump enough power through your mains to have a significant response in the range that a good subwoofer dwells. When you get your sub back and callibrated, try a movie with a good bass track (they're are so many nowadays) with your sub on and mains set to small, then switch the sub off and run the mains as large and you'll see whart I mean. Carl
 

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Quote:
Originally Posted by 04FLHRCI
I plan on crossing my mains over around 40Hz. I've been researching subs in the 15" and 18" range since they'll essentially be running between 15Hz-40Hz. Currently, it appears that the goals I have set well best be achieved via the DIY route. I prefer a sealed enclosure, and the top two "off-the-shelf" contenders I have penciled in are ACI (Maestro), and Velodyne (DD15/DD18). I'm not sure if a pair of Maestros will be sufficient, and the wife has already vetoed either pair of the Velos (6k-8k). I'm going to try and exercise patience to see what drivers are rolled out over the next 90 days.


Rumor has it that Bosso is working on something; with him in the design loop the product has to be good!


Now where is that Bosso anyhow???


Regards,


Larry
A good rule of thumb is that your mains should be able to reproduce an octave below their crossover setting. A higher crossover like 80Hz also helps eliminate some bass cancellation issues from multiple sources. Play around with the crossover and see the point that works best for you. Don't be afraid to try 60 or 80.
 

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Quote:
Originally Posted by cecaa850
A good rule of thumb is that your mains should be able to reproduce an octave below their crossover setting. A higher crossover like 80Hz also helps eliminate some bass cancellation issues from multiple sources. Play around with the crossover and see the point that works best for you. Don't be afraid to try 60 or 80.
Hmm, yes; I've heard of this. My mains will have dual 10s per channel, and should reach down into the lower 30s, maybe upper 20s. Perhaps 60Hz may be a good starting point. I do plan on playing around with it a lot. I just thought that if my mains were up to the task that having a larger sub for HT use would work well.
 

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Ritter,


I was surprised to find out that my mains were not falling off much at 20 Hz either, and when properly placed they sound great (this caveat included because current setup is a compromise with spouse) up to a relatively high volume. They are a pair of Definitive BP30s. Remember, everything is personal taste. I still like to listen to my old Polk SDAs though sometimes I think it's nostalgia.


If you can crossover properly to the sub at 40 to 45 Hz, and actually higher in some cases, your mains and it's amp will not be working nearly as hard because they will no longer be asked to come as close to full extention (or in fact come to full extention) when lower frequencies are required at high Db. Additionally, if the speaker without sub is required to produce a loud 30 hz wave and at the same time it is required to produce a loud 400 or 700 Hz wave it is less able to faithfully produce both requests without at least some distortion simply due to the physics of speaker construction.


I too think your problem is the crossover.


I also think it's interesting that so much emphasis is placed upon flattening the frequency response of audio in general. I think it's a good starting point, but you should listen to something that sounds good to you. It's possibly for a room to have dips, that when (supposedly) compensated to correction sound worse. I assume (I know I shouldn't assume) that the correction is either causing a resonance or perhaps distortion in the driver itself.


Good luck,

Bill
 

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Discussion Starter #9
Yes. Experimentation.


I have a Krell pre/pro with copious EQ options- I got the system pretty flat +-3db but the sound was more veiled than "unflat" without the EQ. I prefer it unflat and unveiled. But thats me.


I also tried the many Krell x-over options (and with/wothout BFD para eq) when running the sub and but FOR MUSIC- no sub sounds best IMO. Sometime less is more.


That also said, the Velo is +10 yrs old and has seen its day. I'll retry with the VMPS when it arrives.


For now I'll run a sweep and see what freqs I'm missing but it still say it sounds great.
 

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Quote:
Originally Posted by cecaa850
A good rule of thumb is that your mains should be able to reproduce an octave below their crossover setting. A higher crossover like 80Hz also helps eliminate some bass cancellation issues from multiple sources. Play around with the crossover and see the point that works best for you. Don't be afraid to try 60 or 80.
While I see many talking about this supposed guideline, it tends to not bear out well in the real world. The presumptions this recommendation is based on are incorrect for many/the majority of systems. In many cases you will get good results crossing over fairly near to the natural roll off of your speakers. Again, this depends a bit on your room and the crossover options in your pre-pro.


There is no requirement for the mains to be flat an octave lower than the crossover point. The only requirement is that the combination of the sub(s) and main speakers results in a reasonably flat integration without over-driving the mains under most listening conditions.
 

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Discussion Starter #11
Just measured my speakers/room without a sub:

I'm pretty flat then +2db at 25Hz then down 12db at 20Hz, so somewhere south of 25Hz I lose it but am pretty good until then. Thats sitting in/close to a null as best I can tell.


I do have an annoying suckout at 50 Hz that I'd like to do something about - I know- a new house (and room) . Thats the plan for 2006. Purpose build a music (primary)/theatre (secondary) room.


When we do that I'll be doing IB but the VMPS will bridge the 8-12 mos. or so to build.

Anyone want a 12 month option on a VMPS Larger? Actually I may use the drivers so check that offer.
 

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Yes I agree that there is a misconception about needing speakers that extend an octave below the crossover.


I think it is mostly based in the misunderstanding of what happens at the crossover. Many people think that if you set a crossover of 80 Hz the mains speakers start to roll off "at" 80 Hz and therefore need to have strong extension past that point in order to not have a frequency dip. In fact, the speakers and the sub both start rolling off "before" the crossover so they are each producing half the sound at the crossover with therefore should result in a flat and seamless transition. If you look at that situation you will see that your main speakers are already rolled off quite a bit at the crossover point and therefore do not have to extend an octave below the crossover.


Attached is a horribly crude drawing of what the crossover frequncy region will look like.
Yes, I know it is not to scale. I graphed it out in Visio in about 30 seconds.

 

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Perhaps, but I still think it is important to set the crossover a decent amount higher than the -3db point. When the lower end -3db point is reached, doesn't this usually mean the speaker is very close to riding the edge of its limits? A FR dropoff line is limited by excursion, enclosure size, and what else? When playing the frequencies at or below the -3db point, doesn't the distortion start to grow tremendously? Now I don't know what, if any, truth there is to one octave above the -3db point, but a decent amount above it to ensure as little distortion as possible makes sense to me.
 

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Discussion Starter #15
So if I have a significant drop off somewhere between 20 and 25hz- where should I crossover- 40hz?


The prob with the Velo is that it has a fixed x-over internally (80hz I think) so I use the one in the pre/pro- now I have two x-overs in the chain. Add in the BFD and you can begin to see the reason for the signal degradation.


I think the VMPS only comes with a fixed high pass filter so I can use the x-over in the pre/pro and elimanate at least one item in the chain. Less is more in audio, no?
 

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Quote:
Originally Posted by ritter
So if I have a significant drop off somewhere between 20 and 25hz- where should I crossover- 40hz?


The prob with the Velo is that it has a fixed x-over internally (80hz I think) so I use the one in the pre/pro- now I have two x-overs in the chain. Add in the BFD and you can begin to see the reason for the signal degradation.


I think the VMPS only comes with a fixed high pass filter so I can use the x-over in the pre/pro and elimanate at least one item in the chain. Less is more in audio, no?




The low pass filter in the subwoofer is not a "crossover". It is just a low pass filter.


In my system, I have large three way R & L mains (set to large), and I use this additional subwoofer low pass filter to increase the filtering of bass above 80hz that comes from the subwoofer. You can hear the difference, and you can see the signal improvement with a True RTA sweep.
 
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