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(4) Sealed 21": Funk Audio UH-21v1


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#121 Infrasonic

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Posted 25 April 2017 - 11:34 PM

I still, reluctantly, use Photobucket.

 

It has a very annoying interface full of countless features bullshit but.... I'll tell ya, everything still works. Even all my old MySpace memes from 10yrs ago.

 

 

And it's free.



#122 chrapladm

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Posted 26 April 2017 - 01:32 AM

Same here Scott. I have always used Photobucket. I dont have a million memes but have used it since my Myspace account also. AND ya that dates me to 13 years when I first joined Myspace. :)


"Music is not in the notes, but in the silence between."


#123 phillip

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Posted 26 April 2017 - 10:58 PM

imgur is the best :D



#124 Harbottle

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Posted 15 May 2017 - 03:20 AM

Post edited due to lack of relevance.  :(

 

Amazing build SME.



#125 SME

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Posted 17 May 2017 - 10:16 AM

Sorry for the lack of update.  I'm knee deep in developing the next gen tools for speaker and room EQ.  These tools will allow me to take full advantage of my custom DSP solution including the ability to do sophisticated crossovers in which each mains channel gets rendered to each of the subs differently.  This is taking longer than I expected, for various reasons, but I'm getting close.  I'm real eager to get this done so I can hear these subs at closer to their full potential.

 

My preliminary work suggests I'll be able to get a very tight, near zero decay response across all 7 seats of my sectional from 20-70 Hz or so using the front subs alone.  I'm very happy about that.  I hope that by steering more sound into the middle of the room, I get a higher ratio of sound to room shake, at least for frequencies above 30 Hz or so.  The reduction of decay time may also help.

 

I am surprised by how uneven my response is in the octave between 9-18 Hz.  Seat-to-seat variation is quite high for some frequencies in that octave if I use identical EQ for the two subs down there.  Being that I don't have nearly as much headroom to work with down there as I do above, I have to make some compromises.

 

I also noticed a significant narrow dip at around 11 Hz with both subs in all locations measured.  I now suspect this dip is caused by my ceiling resonating and transmitting (leaking) sound through it.  The evidence?  A sine wave of around 105 dB at the seats at around that frequency makes my hanging dining room lamp hop on its chain and start swinging.  I'm a bit concerned about what more SPL will do there if sustained, so I think I will leave the notch there or even deepen it on purpose.  Indeed, one key to minimizing house shaking may be to find and notch out the worst offending resonances that often leak too much sound to be worth "fighting for" in the first place.

 

Above 70-80 Hz, the subs in-room get a lot messier.  I'm still working on the bits of tools I need to EQ higher than that, particularly being that the crossovers are important.  I think I'm going to still want the near-field MBMs.  The near-field locations seem best for these troublesome frequencies.

 

I need to post pictures of all this stuff.  I apologize for being so lame about pictures, but they will come once I get through this current work.  Then I need to seriously start watching some movies.  :)



#126 Infrasonic

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Posted 17 May 2017 - 06:21 PM

In room treatments are optimal for "fixing" issues from 50-200hz in most rooms.

 

SBIR is usually the reason that region is "messy" in a lot of rooms.

 

Imho, nearfield MBM's are not a "fix".

 

Wow. I used a lot of quotes. :P



#127 andy497

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Posted 19 May 2017 - 08:32 PM

SME, are you DSPing with IIR or FIR?  I was imagining lin. phase crossovers if you're doing complicated mains/subs blending, but at the low frequency end like that you're talking huge numbers of taps and possible major pre-ringing.

 

I'm now very curious what you mean by each crossing mains to each sub differently.  Can you elaborate?

 

Sorry for the lack of update.  I'm knee deep in developing the next gen tools for speaker and room EQ.  These tools will allow me to take full advantage of my custom DSP solution including the ability to do sophisticated crossovers in which each mains channel gets rendered to each of the subs differently.  This is taking longer than I expected, for various reasons, but I'm getting close.  I'm real eager to get this done so I can hear these subs at closer to their full potential.

...



#128 SME

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Posted 20 May 2017 - 10:27 PM

SME, are you DSPing with IIR or FIR?  I was imagining lin. phase crossovers if you're doing complicated mains/subs blending, but at the low frequency end like that you're talking huge numbers of taps and possible major pre-ringing.

 

I'm now very curious what you mean by each crossing mains to each sub differently.  Can you elaborate?

 

I'm using both IIR and FIR but mostly FIR now.  FIR filters are just so much easier to work with if one has the DSP capability and horsepower.  The filters are mostly minimum phase right now, but I am finding use for some excess phase delay in a few places.  The pre-ringing is very minor in those examples.  And anyway, I don't have a "video delay" capability, so I can't tolerate much extra latency anyway.

 

Linear phase crossovers are kind of a fantasy when it comes to mains/sub blending in small rooms.  My room response suffers from substantial acoustic problems right in the range of frequencies that the typical main/sub XO (e.g. 60-120 Hz) falls in.  I'd bet it's not just my room that does this but almost *every* small listening room.  A lot probably has to do with ceiling heights tending to fall in the 7-10 foot range.

 

In any case, this fact makes crossover between mains and subs a total crap-shoot.  The best tool most people have to optimize this blend is adjusting the sub delay.  However, even if the sub impulse response is perfectly time aligned to the other mains, the blend is often very poor.  Better results are often achieved by "optimizing" the delay to achieve the smoothest response with one channel, but this frequently involves compromising smooth response of the other mains channels, to the particular detriment of 2 channel music.  Finally, this kind of optimization rarely takes into consideration multiple listening locations.

 

I aim to do much better.  What I mean by crossing each main to the subs separately is the the signals that go to each of the subs are different depending on which mains channel the sound came from.  For example, if I play a sound in the left mains channel, the subs will see different signals than if I play the same sound in the right mains channel or the center or one of the surrounds.  I may even go a step further and process bass for the left+right phantom center differently, but that's a ways into the future.



#129 andy497

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Posted 23 May 2017 - 06:50 PM

I'm using both IIR and FIR but mostly FIR now.  FIR filters are just so much easier to work with if one has the DSP capability and horsepower.  The filters are mostly minimum phase right now, but I am finding use for some excess phase delay in a few places.  The pre-ringing is very minor in those examples.  And anyway, I don't have a "video delay" capability, so I can't tolerate much extra latency anyway.

...

 

Cool.  Re: horsepower, yeah I found that was the easy part.  I have an aging intel i7 for the HTPC, and I found that 64k taps x 7 channels took a few % of cpu.  No big deal.  The much bigger pain is the video delay, or lack thereof.  I went down to 16k taps and am doing everything I can to speed up the audio chain and slow down the video one, but it's still never enough.  Jriver, which I love/hate but mostly hate, handles movies fine, but I find I watch a lot more youtube in practice.  Adding to that, shrinking buffers too much gives me popping and crackles, and I hate that even more than bad lipsync.  First world problems...



#130 SME

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Posted Yesterday, 10:14 AM

Cool.  Re: horsepower, yeah I found that was the easy part.  I have an aging intel i7 for the HTPC, and I found that 64k taps x 7 channels took a few % of cpu.  No big deal.  The much bigger pain is the video delay, or lack thereof.  I went down to 16k taps and am doing everything I can to speed up the audio chain and slow down the video one, but it's still never enough.  Jriver, which I love/hate but mostly hate, handles movies fine, but I find I watch a lot more youtube in practice.  Adding to that, shrinking buffers too much gives me popping and crackles, and I hate that even more than bad lipsync.  First world problems...

 

Well, I managed to overload a single core i5 (the original Neleham) 2.4 GHz DSP in the past few days using something like 24 FIRs with 165887 taps each.  That's in addition to several other processing elements, so the FIRs alone may not be to blame.  I had to bump my block size up from 256 to 1024 to get it to run stable.  :(  With three periods, that's 64 ms latency out of the gate.  Thankfully, my Denon AVR supports a max distance of 60 feet, and it looks like it actually does buffer and delay the video.  That helps *a lot*.  I'll still probably try to reduce the size of the filters, but I kind of wanted to see what I could get away with.



#131 SME

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Posted Yesterday, 10:32 AM

Sorry for not updating, but I've been super busy working on my next gen software tool and then using it to create an optimized DSP config.

 

Unfortunately, the new software tool proved to be cumbersome in its first iteration.  The plotting library I used proved to be slow and buggy, so I will have to re-write a lot of the code.  However, I was very eager to get *something* in place to improve my sub responses, so I muddled through with what I had.

 

The second part took a while.  Having a lot more capability at my finger-tips, I wanted to experiment to see what I could achieve.  Needless to say, the deep bass cleaned up beautifully.  I fixed the tendency of the bass to concentrate on one side of the room and achieved very even coverage between 20-40 Hz, and for all practical purposes, the decay is essentially instantaneous.  Wall shaking seems to be considerably improved.  I think the ULF is better too, but I had to sacrifice more headroom for it than I'd like to admit.

 

The mid-bass is where things proved to be painful.  The region from about 70-120 Hz is where I spent most of my effort, and I'm not at all satisfied with the result.  Pretty much everything sucks there.  My mains, subs and MBMs all struggle to cover that range well due to their placements and the properties of the room.  The MBMs cover it better than the other sources, but they still need a lot of boost to get there, and the seat-to-seat variation is still uneven.  I will soon revisit it to improve on it.  I think it has the potential to be lot better.  However, I'm thinking I'm going to want the 4 independent MBMs for the sofa as opposed to 2 MBMs behind and two up front stacked between the subs and the mains.  I'll probably also want more bass traps in the right places.

 

Anyway, I'll try to very soon get the pictures fixed and post some nice measurements to show what I've been up to.



#132 SME

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Posted Yesterday, 10:57 AM

Oh yeah, I forgot to mention that I watched Star Wars: The Force Awakens with BEQ and flat response to 5 Hz, with bass played back more or less at reference.  That proved to be an excellent work-out for the system.  The amp got pushed to near its limit repeatedly but never clipped to my knowledge.  The subs never made any untoward sounds.  In fact, the sound remained subjectively very clean, even with violent levels of ULF going on.

 

I also did some testing with the famous "How to Train Your Dragon" crash scene.  With my current EQ config, I can't go beyond "-9 dB" or so without seeing "the orange (clip) lights" on the amp.  I didn't go much beyond there at all, but I didn't hear any unpleasant sounds when this was going on.  I think the amp lights up orange a bit before it actually clips when its getting a lot of ULF, but I don't know.

 

One thing I can't readily explain is that I seem to prefer these calibrated a few dB hotter than the old subs for the subjective quantity of bass.  Is it because their distortion is so low?  I don't know, but I do know that these sound and feel incredibly clean and powerful once they get above the masking thresholds.  Indeed, I'm surprised to be experiencing what I would describes as slam sensations rooted at deep bass frequencies.  I've generally thought of slam as being a 50 Hz+ sort of thing, but these seem to deliver the feeling a lot lower.  It also feels like a lot more tactile sensation comes from the air instead of the furniture.






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