Why is slope never discussed wrt subwoofer integration
- Thread starter tomlinmgt
- Start date
enginedr
Super Member
I do understand that . I enjoy your threads very much they are most informative . The topic of subwoofer integration caught my attention.
My room is 12 x 18 with a 6 foot opening to the dining area .
my system is against the long wall . I sit against the opposite wall . head is 8" from wall. My system is using Ohm Walsh 2000 main speakers siting on top of 2 - REL Q201E subs . The speakers are 34" from the front wall treated
with a 2 -24x48" acoustic absorber panels . The left wall is 6 ' from the speaker. The right speaker fires into the dining area . I use my DSPeaker as
my DSP as well as DAC . I have it in the tape loop of a CI audio passive pre
the pre has 2 sets of RCAs out one set to the subs the other to the amps .
The DSP is set to correct from 500 hz and down . Both the mains and subs
are being corrected in that FR range . I have not heard a system sound as balanced as my own . I would like to thought . I have a vinyl rig and recently
changed the cartridge and noticed the difference . I feel the 40 bit chips in the DSPeaker are pretty transparent . I Live in Manhattan and have many a
high end dealer to audition gear with . But as you preach the rooms just
Suck. I want to be impressed . So if you are in NYC you are welcome to give
a listen . Thank you for your great input to this forum .
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Rob41
Don't stop believin'
This is what has been bugging me after just building my speakers. I have used my MiniDSP and made adjustments to where I'm pleased with the results. But, I'm vaguely aware that there can be phase issues and I don't know how to go about determining if I actually have issues.
The crossover frequency and slope are both integral parts of a filter. If you want to keep the same frequency, but with a different slope, then what you need is a different filter.
I think that purely passive filters in the subwoofer range would have such huge (and expensive, and inefficient) components that that's why you don't see them much. But there are DIY analog active filters that aren't hugely expensive, and you can design them to get a multitude of slopes.
http://sound.westhost.com/articles/active-filters.htm
A mic, computer, and Holm Impulse (free) and you can measure (and see on a graph) the phase relationships.
http://www.holmacoustics.com/holmimpulse.php
If your mains need a sub, they aren't very good mains. If you need to roll off the low end of your mains, you probably didn't need a sub to begin with, other than maybe to rattle your windows or bother your neighbors. EQ's are cheap and effective.
By your comment, you have not had a lot of experience with a good crossover and a distributed bass solution. EQ's add noise and don't have the adjustments needed for good sub integration. And yes my Magnapans only need the subs for slam on certain types of music - when they are needed they are there! FWIW
Regards,
Jim
You might want to check out the new I Tech HD Crown amps, as they have just about everything built in the amp that I think anyone would want to have. Just go to the specs and look in the advance mode settings.
Edit: What I am getting at is you don't really need the Active Crossover anymore as the new amps have those operations and more built right into them. And since your looking for just sub integration you can still use your AC for your upper ranges for amps that you prefer and just use amps with these features for the sub.
http://rdn.harmanpro.com/product_do...0811-1_I-Tech_HD_operation-08-13_original.pdf
Edit: What I am getting at is you don't really need the Active Crossover anymore as the new amps have those operations and more built right into them. And since your looking for just sub integration you can still use your AC for your upper ranges for amps that you prefer and just use amps with these features for the sub.
http://rdn.harmanpro.com/product_do...0811-1_I-Tech_HD_operation-08-13_original.pdf
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edwyun
Super Member
I think the issue is wanting an analog active crossover, and not a digital one - whether in a separate unit or integrated into a power amp.
For me, what is the point of vinyl, reel to reel, or cassette tape if it will go through an ADC and a DAC in a digital active crossover/power amp? Seems to me it defeats the purpose.
Like I said, the digital ones are getting better, but I still prefer discrete analog.
Rob41
Don't stop believin'
Thanks for the link Jeffery. I downloaded and installed. Tomorrow I'll give it a go. :thmbsp:
edwyun
Super Member
I don't lose sleep over it but there is a reason why the 24dB/Oct Linkwitz-Riley is the generally the standard these days. 360 phase response, summed signal giving a flat response (no amplitude change) etc.
I suppose a 6dB/Oct would work too but most drivers can't perform that well at their extremes.
And remember, all this theory about crossovers assumes perfect response from the drivers at the crossover points. That is not the case usually.
Rob41
Don't stop believin'
Thanks for the information. Ya know, I feel like I'm living that expression of knowing enough to be dangerous. I've never built a physical crossover yet I have amazing abilities with just a keystroke. Maybe not the ideal way to approach this but still it's opened up a whole new world of possibilities that has already payed off for me.
It has inputs for both analog or digital. The OP's sources are all digital last I knew. But anyway I just thought it might be something to consider.
edwyun
Super Member
yeah, those software-based systems let you model and test. So you could easily narrow down what you really need.
edwyun
Super Member
Agreed. I learned something new too. Didn't know those types of amps existed. :thmbsp:
Bob Orme
Active Member
I didn't mean to thread jack your post, but you posed a question about a subwoofer slope without specifying what speaker woofer roll-off you are trying to match. Since then, you implied every "flagship" JBL, Infinity and Polk speaker made is inferior. They all need a sub. Rob41 went even further and stated that no one makes a stereo speaker that can't benefit with the addition of a subwoofer. That sounds like a line from a big box stereo salesman. These are the best speakers you can buy, but buying this other stuff will make them even better because they will be louder!No.
I can assure you I (and many others) have been down the path you suggest with mains that are indeed very good (in my case, several flagship full range designs from the vintage era and in a room with extensive acoustic treatments) and that does not guarantee flat and accurate low frequency response because room acoustics and the way they adversely affect LF reproduction simply won't allow it. And at one time I thought an EQ was the cure and actually considered it as critical a piece to have in the rig as the source component itself. Experience, experimentation, and knowledge have taken me beyond that highly compromised and flawed methodology and if you'd consider the basic science that dictates all of this you'll understand why.
Yes, at one time I thought my EQ assisted JBL, Infinity, Polk, etc. full range designs with an EQ made some pretty awesome sounding bass...but then I embraced the science, took the proper approach and realized how much I'd been missing and, frankly, screwing it all up. This could be a game changer for you, too...if you're willing to let go of your methods and beliefs. This is the other side, the next level, the place you get to and say "holy ****...I've been doing it all wrong".
Have a look at this link and you'll start to understand the concepts at play here.
http://www.audiokarma.org/forums/showthread.php?t=291904
I've worked in rock concert sound production and I'm very aware of the acoustical physics involved in filling a venue much larger than the average living room or man cave. Pink noise generation with EQ would result in a flat sound curve from multiple speaker stacks in the venue. Low audio frequency reproduction is all about moving air. Increasing the production of low (often subsonic) audio frequencies with the addition of subwoofer(s) is not necessary in most home stereo systems, unless you want to rattle the windows or piss off your neighbors. I don't think pointing that out makes me a jackass...nor would it make anyone else who might agree with me to be a jackass.
tomlinmgt
Lunatic Member
Actually, I wasn't looking for advice or information for a particular problem I have...I was asking a general question that addresses a broad range of scenarios, but all dealing with the integration of a LF support system with main speakers and how slope, in particular, influences the quality of that integration.
I made no such implication about their quality. I did suggest that regardless of their performance capabilities, room acoustic issues will compromise their ability to fully reach those capabilities, particularly in the low frequency regions.
So long as that loudspeaker is suffering from the acoustic issues that can and do exist in practically every domestic living space...with the exception of unusually large rooms...that statement is pretty accurate, except I maintain that one subwoofer is typically not sufficient to overcome said acoustic issues.
If the suggestion is that one sub will improve the situation and louder is better then yes, that does sound like a sales pitch from a big box store. If it were someone who actually understood the science they would be suggesting several subwoofers....which Rob did when he specified "distributed bass"....and not with the intention of achieving "louder" but instead "better".
Large room/outdoor acoustics and small room/domestic living space acoustics are two entirely different animals and can not be dealt with the same way.
You're missing the point and if you understood the physics behind what is occurring in the small room acoustics scenario you'd better understand what is happening and what has been suggested as an effective and productive way to deal with it. Did you read the link on "distributed bass" I provided you? It has absolutely nothing to do with "rattling windows and pissing off neighbors". It has everything to do with achieving a balanced low frequency response at the listening position by using a supplemental low frequency reproduction system that strategically locates several subwoofers in the room so the inherent room acoustic issues that prevent the balanced reproduction of the low frequencies from the main speakers are overcome. In addition, because several drivers are sharing the workload of just a few distortion can be reduced significantly if not eliminated entirely. And this is not with regard to distortion at high SPL only, but at all volume levels (beneath the level where any one of the LF drivers begins to demonstrate break up).
No, at this point it doesn't and I didn't call you a jack ass (though I can see where my wording could've been better oriented to avoid any confusion) as the post you're referencing wasn't directed at you specifically but rather anyone who maintains that all one needs for balanced low frequency reproduction is a set of full range speakers and an EQ after having been presented with the science that clearly demonstrates that belief system to be tragically flawed.
I'm going to give you the benefit of the doubt and assume you haven't looked into the science behind small room acoustic physics. I have nothing to sell, no self-serving agenda to advance, or desire to make you or anyone else look like a jack ass. I'm only trying to help and here's some info that illustrates the theories from which I base my comments.
- Michael
https://www.youtube.com/watch?v=g3aHwTkMfBc
http://www.gikacoustics.com/video_bass-traps/
https://www.youtube.com/watch?v=xECtAruK0fM
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Rob41
Don't stop believin'
Hopefully this thread shifts back to the topic that was raised rather than weather subs/distributed bass is needed. Those that aren't open to the science of acoustics in their home listening space simply will not change. Okay, enjoy what you have.
Sorry if I played a part in side tracking your thread Michael. Your topic of slope as it applies to sub woofer integration is very interesting and an awful lot can be learned from this discussion.
Sorry if I played a part in side tracking your thread Michael. Your topic of slope as it applies to sub woofer integration is very interesting and an awful lot can be learned from this discussion.
HTWillie
Super Member
For cheap-ish analog active crossovers you might consider something by audiocontrol. They're more known for their car audio products, but they've made hifi gear since the 1970's. Anyhow, find a pdf online of the Phase Coupled Activator.
The bass enhancement aspect of the device may or may not be to your liking (I have fun with it), but in the same chassis they include a 2-way active crossover and subsonic filter, the frequencies of which are "programmed" by inserting different resistor networks in the socket on the board. And you can build your own for whatever frequency you wish.
Now the interesting thing is the slopes. I own or have owned about a dozen audiocontrol products and all their crossovers are either 18dB/octave using a six resistor network, or 24dB/octave using an eight resistor network.
I can do the math and guess that if audiocontrol ever wanted to do an active 12dB/octave crossover, they would do it with a four resistor network, and a 6dB/octave slope with only two resistors.
Luckily I'm content my audiocontrol gear as-is. And I'm too cowardly to experiment on my own gear. Yet the hacker side of me thinks if I wanted different slopes, it'd be simple to just build resistor networks and leave out a few select resistors. But which ones? (they're all the same value, for any given crossover frequency) And for each resistor left out, do I short that connection for zero resistance or leave it open for infinite R?
I've seen textbook examples of active crossover networks, and if I studied topology, the feasibility and details of this hack might be obvious. But I haven't. I'm lazy like that. Maybe somebody else has.
Anyhow, look at audiocontrol's Phase Coupled Activator, or even one of their car audio crossovers if it's just for test-bench, playing around with it and learning. I think it would be a great platform to goof around with and try things out.
The bass enhancement aspect of the device may or may not be to your liking (I have fun with it), but in the same chassis they include a 2-way active crossover and subsonic filter, the frequencies of which are "programmed" by inserting different resistor networks in the socket on the board. And you can build your own for whatever frequency you wish.
Now the interesting thing is the slopes. I own or have owned about a dozen audiocontrol products and all their crossovers are either 18dB/octave using a six resistor network, or 24dB/octave using an eight resistor network.
I can do the math and guess that if audiocontrol ever wanted to do an active 12dB/octave crossover, they would do it with a four resistor network, and a 6dB/octave slope with only two resistors.
Luckily I'm content my audiocontrol gear as-is. And I'm too cowardly to experiment on my own gear. Yet the hacker side of me thinks if I wanted different slopes, it'd be simple to just build resistor networks and leave out a few select resistors. But which ones? (they're all the same value, for any given crossover frequency) And for each resistor left out, do I short that connection for zero resistance or leave it open for infinite R?
I've seen textbook examples of active crossover networks, and if I studied topology, the feasibility and details of this hack might be obvious. But I haven't. I'm lazy like that. Maybe somebody else has.
Anyhow, look at audiocontrol's Phase Coupled Activator, or even one of their car audio crossovers if it's just for test-bench, playing around with it and learning. I think it would be a great platform to goof around with and try things out.
