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Official Rythmik Audio Subwoofer thread - Page 9

post #241 of 15160
Quote:
Originally Posted by Rythmik View Post

The implementation of my Denon is closer than the Figure 3-3. The so-called optional 120hz LFE filtering is there. The LFE+main is there (ie, the LFE is duplicated via front left/right and sub to create a more spacious bass, haha). If we set the front speakers small, just stick a HPF right at the output of front speakers, instead of swapping between Figure 3-2 and 3-3. For any software/firmware/hardware designer, there is no point of devising two completely different schemes and switch between them (not to mention, it will introduce different latency and hard to compensate them so that all channels arrives at the same time). These flows are actually implemented in digital domain. In Figure 3-2, subwoofer is mandatory. Therefore this scheme is closer to systems with subwoofer built in such as Bose

[EDIT:] My denon can xover as low as 40hz. I wonder who would use that (or should I say who would design that) as he may lose the signal from 40hz to 120hz? That is almost two octaves !!

You're right, a bass management architecture that mixes the LFE into the L and R channels, then crosses over the whole LR+LFE pair from the L/R to the sub will not lose any of the LFE, regardless which frequency is chosen. The virtue of such a scheme is that frequencies that are sent to the sub are directly limited by the LP part of the crossover, which makes life easier for the sub designer. The problem is that you now have a potentially significant part of the LFE in the LR, which now must be able to handle the additional 10dB of headroom in that channel. If you set the crossover to 40Hz, for example, your mains would have to handle that +10dB from 40-120Hz. That could be a challenge.

On the other hand, if you follow the scheme in the diagrams I included, you see that the whole LFE goes to the sub, which presumably and historically is designed precisely to handle the extra headroom requirements. Unfortunately for you, the subwoofer designer, it also requires you to have frequency response up to 120Hz, if nothing is to be lost from the LFE channel.

It should be relatively easy to find out which of these is running in any given AVR using a source sending a sweep to the LFE only. Doesn't the Avia test disc have this?
post #242 of 15160
My Sony AVR allows me to set the LFE gain to +10 or 0 dB so I can compensate the dynamic range issue. (I haven't looked at other receivers to see if they can also do that.) But, does that mean everything is OK, or that if I set 0 dB the LFE output would be too low? For now I have it left on "auto" (whatever that means to Sony). Based on my measurements (test tones and SPL meter) and listening, my system sounds OK, implying the AVR is handling the bass (regular and LFE) OK for music and movies in my situation (main L/R and subs in parallel so the AVR essentially sees a pair of very full range L/R speakers and no sub). I agree the mains must still handle all the low frequency content, a potential issue.

Good posts, thanks! - Don
post #243 of 15160
I just ordered my D15SE and I can't wait till they're back in stock and shipped. I was notified my Ascend Audio that they should be receiving their shipment late March. Proud to be part of the Rythmik family after a lot of research into many different subs.
post #244 of 15160
Quote:
Originally Posted by DonH50 View Post

My Sony AVR allows me to set the LFE gain to +10 or 0 dB so I can compensate the dynamic range issue. (I haven't looked at other receivers to see if they can also do that.) But, does that mean everything is OK, or that if I set 0 dB the LFE output would be too low? For now I have it left on "auto" (whatever that means to Sony). Based on my measurements (test tones and SPL meter) and listening, my system sounds OK, implying the AVR is handling the bass (regular and LFE) OK for music and movies in my situation (main L/R and subs in parallel so the AVR essentially sees a pair of very full range L/R speakers and no sub). I agree the mains must still handle all the low frequency content, a potential issue.

Good posts, thanks! - Don

Ugh - you stumbled upon a huge can of worms. You'll have to check the AVR threads and see if your Sony handles the LFE +10dB boost correctly. There were some (many/few) that did not correctly apply the required 10dB boost and even if you manually applied it (assuming your AVR had that function), it then resulted in the sub being 10dB "hot" for other than LFE sources.
post #245 of 15160
Yeah, been there, done that... I think it is actually working OK now, though I haven't been able to measure it yet with a video test DVD, because I am running the sub as part of the mains (so far as the AVR knows) instead of using the sub output from the AVR. At least my initial trials with a couple of CDs and a movie seem OK.

I am learning a lot about LFE in the process, not a bad thing. Hopefully.

In the meantime, I am going to go down after supper, watch the snow, and listen to the system for a while
post #246 of 15160
Quote:
Originally Posted by fyzziks View Post

You're right, a bass management architecture that mixes the LFE into the L and R channels, then crosses over the whole LR+LFE pair from the L/R to the sub will not lose any of the LFE, regardless which frequency is chosen. The virtue of such a scheme is that frequencies that are sent to the sub are directly limited by the LP part of the crossover, which makes life easier for the sub designer. The problem is that you now have a potentially significant part of the LFE in the LR, which now must be able to handle the additional 10dB of headroom in that channel. If you set the crossover to 40Hz, for example, your mains would have to handle that +10dB from 40-120Hz. That could be a challenge.

On the other hand, if you follow the scheme in the diagrams I included, you see that the whole LFE goes to the sub, which presumably and historically is designed precisely to handle the extra headroom requirements. Unfortunately for you, the subwoofer designer, it also requires you to have frequency response up to 120Hz, if nothing is to be lost from the LFE channel.

It should be relatively easy to find out which of these is running in any given AVR using a source sending a sweep to the LFE only. Doesn't the Avia test disc have this?

In this debate is it being assumed that there is full content between 80-120Hz? The LFE has a brick wall at 120Hz (no content at 121) and the engg designed a smooth roll off from 80Hz to 120Hz which means there is not that much useful info there anyway and thus the THX recommended 80Hz for LFE.
post #247 of 15160
Quote:
Originally Posted by Zmaximus View Post

In this debate is it being assumed that there is full content between 80-120Hz? The LFE has a brick wall at 120Hz (no content at 121) and the engg designed a smooth roll off from 80Hz to 120Hz which means there is not that much useful info there anyway and thus the THX recommended 80Hz for LFE.

so basically if this is confirmed that means its ok to xover at 80hz regardless of the dd scheme for bass management.
post #248 of 15160
Normally, I will have photo of new products professionally done. But I bet some are very eager to see the photos. So I decide to provide some that are done by me, an amateur.



From left to right, F15, E15, and F12. E15 is as narrow as we can get. To keep as much internal space, I keep the height same as F15 and depth 1" shorter. The tall and narrow front baffle further makes it look not as large.



Here is the driver DS1510. It weighs 30lbs net.




Here is the amp. U571 is not included. The 18000uF/63v caps are from Panasonic and I purchased in US and air ship to my supplier. They cannot find anything as volume efficient as these Panies.


post #249 of 15160
Quote:
Originally Posted by porksoda View Post

so basically if this is confirmed that means its ok to xover at 80hz regardless of the dd scheme for bass management.

Yes since your LPF at 80 is going to match the smooth roll off anyway...
post #250 of 15160
Quote:
Originally Posted by porksoda View Post

so basically if this is confirmed that means its ok to xover at 80hz regardless of the dd scheme for bass management.

Here are couple of articles I found in archives to shed some light on the discussions...

http://www.hometheaterhifi.com/techn...equencies.html

http://www.hometheaterhifi.com/techn...und-sound.html
post #251 of 15160
Brian

Picts look great! any sepcs on the d1510/

Thanks
post #252 of 15160
Wow Brian... those are sweet! I noticed that my F-15 shipped yesterday... is that one in the picture mine?
post #253 of 15160
Quote:
Originally Posted by Zmaximus View Post

Yes since your LPF at 80 is going to match the smooth roll off anyway...

Quote:
Originally Posted by Zmaximus View Post

Here are couple of articles I found in archives to shed some light on the discussions...

http://www.hometheaterhifi.com/techn...equencies.html

http://www.hometheaterhifi.com/techn...und-sound.html

thanks... i usually xover at 70 or 80hz myself so this is a good re-assurance. I find with my "full range" towers if i use them as large i seem to get a bit of boomyness out of them and the highs and mids kinda get lost so i prefer to use them as small.. i have not done a rew in my room and various equipment but i will soon.
post #254 of 15160
Quote:
Originally Posted by Rythmik View Post

Normally, I will have photo of new products professionally done. But I bet some are very eager to see the photos. So I decide to provide some that are done by me, an amateur.

looks good. which amp is that.. is that the new peq2 amp?

I will soon take my pics and post them
post #255 of 15160
Can someone tell me where these units are built/assembled?

And why did they leave the first "h" out of Rhythmic?
post #256 of 15160
Brian:

You recommend to turn OFF the subwoofer when is not in use or may be left ON all the time, say for up to a week or more time?. I ask this because with the new A370PEQ2 amplifier was removed the auto-on funtion.
post #257 of 15160
The units are assembled in central Texas. Rythmik is a brand name, kind of like Krispy Kreme, Toys R Us, etc.
post #258 of 15160
Quote:
Originally Posted by AcuraCL View Post

And why did they leave the first "h" out of Rhythmic?

Why do some brands spell extreme like "Xtreme"...
post #259 of 15160
Quote:
Originally Posted by porksoda View Post

looks good. which amp is that.. is that the new peq2 amp?

I will soon take my pics and post them

Guess its H600PEQ, the one that uses those Pannies
post #260 of 15160
Quote:
Originally Posted by Zmaximus View Post

In this debate is it being assumed that there is full content between 80-120Hz? The LFE has a brick wall at 120Hz (no content at 121) and the engg designed a smooth roll off from 80Hz to 120Hz which means there is not that much useful info there anyway and thus the THX recommended 80Hz for LFE.

OK, first of all, you're right that 80 Hz should be basically fine, since most of the content in the LFE is below 80 Hz. But there are a few more points you may want to consider.

1. The THX 80 Hz value is predicated on old data. A guy with handle "filmmixer" who of course, mixes films in Hollywood for a living, I think said that recently (in the last few years) more and more content was being added in the 80-120Hz region, mainly sparingly, but for dramatic effect.

2. When you add an 80 Hz LP filter to an already filtered roll off, you get a much greater loss at any given frequency since you are cascading filters, and so are changing the sound mixer's (and the director's) intent in that band, e.g. if both you and the engineer are using a 24 dB/octave filter, then at 80 Hz what you hear is -6 dB instead of -3, and at 120 Hz you are down 24 dB instead of 12, etc. Different sound.

3. This is not technical, but social - one of the founding fathers of THX, Tom Holman, is also a principal at Audyssey, and he and Chris Kyriakakis seem to know each other well. ChrisK has very strongly advocated letting the full 120Hz through, which I don't think he would say if Tom had convinced him that THX had it right all along. I think the opposite may be true. Of course, this is all conjecture and maybe irrelevant.

So I think the bottom line is 80Hz LPF is probably OK, but if it doesn't cost too much, or you are a stickler for getting as much of the director's artistic intent as possible, then you may want to try putting the full LFE through.
post #261 of 15160
Quote:
Originally Posted by fyzziks View Post

OK, first of all, you're right that 80 Hz should be basically fine, since most of the content in the LFE is below 80 Hz. But there are a few more points you may want to consider.

1. The THX 80 Hz value is predicated on old data. A guy with handle "filmmixer" who of course, mixes films in Hollywood for a living, I think said that recently (in the last few years) more and more content was being added in the 80-120Hz region, mainly sparingly, but for dramatic effect.

2. When you add an 80 Hz LP filter to an already filtered roll off, you get a much greater loss at any given frequency since you are cascading filters, and so are changing the sound mixer's (and the director's) intent in that band, e.g. if both you and the engineer are using a 24 dB/octave filter, then at 80 Hz what you hear is -6 dB instead of -3, and at 120 Hz you are down 24 dB instead of 12, etc. Different sound.

3. This is not technical, but social - one of the founding fathers of THX, Tom Holman, is also a principal at Audyssey, and he and Chris Kyriakakis seem to know each other well. ChrisK has very strongly advocated letting the full 120Hz through, which I don't think he would say if Tom had convinced him that THX had it right all along. I think the opposite may be true. Of course, this is all conjecture and maybe irrelevant.

So I think the bottom line is 80Hz LPF is probably OK, but if it doesn't cost too much, or you are a stickler for getting as much of the director's artistic intent as possible, then you may want to try putting the full LFE through.

I am not sure what you intended to imply in point 2? LPF at 80Hz does not do anything to 80Hz! The 12/24db would reduce it by that much at 160Hz but there is no content there... The roll off is between 80-120Hz and still exists to date in all iterations...there is no full signal from 80-120 in all my readings, the roll off is not down to zero but more than enough to make that sector functionally not relevant...in addition you are adding a directional event to your sound field (sub would be localizable at that freq)on top of taxing it in a segment where pay off is minimal unless the satellites are very miserable (-3db over 100db). The front three should have information on the the segment 80-120 to compensate fairly well for any perceived loss in that area.
post #262 of 15160
Any chances of a E12 version, that like the E15, is a slightly small (narrower) version of the F12/F15?
post #263 of 15160
Filters aren't perfect, at least real ones... Filters are (typically) specified at the -3 dB point, so the -3 dB point of an 80 Hz LPF is 80 Hz. If you cascade two of them, then at 80 Hz it is -6 dB, with more roll-off up to that point and of course faster roll-off after. This is not true for all filters, particularly various equiripple types (elliptical, Chebyshev, etc.), but hopefully you get the idea.
post #264 of 15160
Quote:
Originally Posted by Rythmik View Post

Normally, I will have photo of new products professionally done. But I bet some are very eager to see the photos. So I decide to provide some that are done by me, an amateur.



From left to right, F15, E15, and F12. E15 is as narrow as we can get. To keep as much internal space, I keep the height same as F15 and depth 1" shorter. The tall and narrow front baffle further makes it look not as large.



Here is the driver DS1510. It weighs 30lbs net.




Here is the amp. U571 is not included. The 18000uF/63v caps are from Panasonic and I purchased in US and air ship to my supplier. They cannot find anything as volume efficient as these Panies.



Excellent Brian. Those are very nice. I love the look of the black 15" drivers!
post #265 of 15160
Quote:
Originally Posted by alphaiii View Post

Any chances of a E12 version, that like the E15, is a slightly small (narrower) version of the F12/F15?

I would like to know the demand. It is possible to do that. All I have to do is to swap the GR12-4 driver's voice coil and put in on DS1200 cone/motor. Please note that the parameter of current DS1200 has been like that for 7 years now. I found it to be almost right at the sweet splot, providing more output around 30-50hz than other drivers. If I do go with E12, the output below 20hz should be the same, but the output between 30-50hz can drop by 1-2db depending on BL value.
post #266 of 15160
Quote:
Originally Posted by Zmaximus View Post

Guess its H600PEQ, the one that uses those Pannies

Yes. That is the H600PEQ.

BTW, I will put out some spec on DS1510 driver this weekend.

For those who eagerly want to order E15 with H600 option, please wait till next Monday when I catch up a bit. I know everyone is eager. But .....
post #267 of 15160
Quote:
Originally Posted by castaƱo View Post

Brian:

You recommend to turn OFF the subwoofer when is not in use or may be left ON all the time, say for up to a week or more time?. I ask this because with the new A370PEQ2 amplifier was removed the auto-on funtion.

Yes. I would recommend them to be on. The ON state only consume 8W without signal. It is really low. Put an auto-on feature can save only 2W. BTW, I recommend everyone to get a "kill-a-watt" meter. It is really useful.
post #268 of 15160
So....which of the Rythmik subs are the most musical?
post #269 of 15160
Quote:
Originally Posted by Rythmik View Post

I would like to know the demand. It is possible to do that. All I have to do is to swap the GR12-4 driver's voice coil and put in on DS1200 cone/motor.

I would be interested in an E12, would be more interest in a D12!!!!
post #270 of 15160
anyone here compare the f12 or f15 with a seaton or empire?
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