Official Rythmik Audio Subwoofer thread - Page 3

I am going to get port caps to help customers build their vented enclosures. The cap I have found is like the following.





The outer diameter is 5-1/8" (130mm). In the past, I have used aeroports and found them to be difficult to install. The above caps is very easy to install. All one needs is 3 steps recess. The first step is 6mm (1/4"). One can use a 1/4" MDF for that. The second and third step can be done by two MDFs, from which we use as double thickness front baffle. There is plenty area we can apply glue and make sure there is no air leak between cap and enclosure without using any screw. The same cap will also be used as inside flared cap.

As with most flared port caps, these caps need special tube, which has a 1/8" wall and 3' 4" in length. To use with our vented enclosure plan, we will cut them into 17-3/5" length. If any of you can think of any project that may use full 3' 4" length, please let me know so I can get a few of them in that length. I only have 4 days to make decision though. Let me know as soon as possible.

If I were to do a bipole sub, with the drivers facing opposite directions, how close should they be to each other? A few inches? Almost touching? Can the be a couple feet apart?

Thanx,

Actually he's basically done what HSU and SVS does for their ported subs... Max extension or Max output... appears that is what his bass extension controls do (and more), however it doesn't seem many owners are actually taking advantage of this tune-ablility. And since there are no ports to be opened or plugged, Brian could have actually put this option on a remote.


Thanks for the kind words, however I'm not always so level-headed... I've had my share of blow-ups and foot-in-mouth episodes. It usually comes from spending too much time on a single forum and losing perspective... which eventually happens to everyone at some point. If I can see it happening to someone else, I try to say something and then walk away from it...

I grew up back when Kaneohe was really "country" with boardwalks in town and the barber shop had saloon doors and the old Pali road was the only way through the Koolau range and on windy days we couldn't get the car (a Ford Anglia) through the pass to get to townside... today its all different (freeways and tunnels).

Sounds like you live out in the pineapple plantations, stuck between mountain ranges. I've lived in many places since my youth and still haven't found anywhere with the beautiful weather like the Islands... with the wild places like the Islands... and with the beautiful ease of the people like the Islands... yes, it's all paradise.

Received my F15 yesterday, watched The Hurt Locker, It was amazing.. Better than SVS PB12-NSD I borrowed from a friend.

Only thing worries me is Audyssey reports subwoofer distance closer than actual. Any one faced this problem ? I manually changed the distance info, but not sure its the right way to go.

I just got my D15SE, but haven't run Audyssey yet. However, Audyssey reports my Velodyne twice as far away (22 ft, vs 11 ft). I might be wrong, but I think this is Audyssey's way of adjusting the phase.

Yes, it is not the physical distance that is being measured but rather the distance in time... phase.

I received my D15SE yesterday.

It is a great looking sub and was packaged very well.

I was getting some buzzing due to a ground loop, but a cheater plug took care of that - it is dead quiet now.

I hooked it up, ran Audyssey (sureshpc - Audyssey place my sub closer, by 6 ft, as well) and listened to some music and watched the latest transformer movie (only recent action movie I have not seen). The sound is very different than what I am used to. My last sub - a 1997 Velodyne VA-1012 was very in-your-face. I knew exactly were it was and I didn't use it for music because it sounds mushy to me. I crossed my fronts (Polk Lsi15s and a CSi40) at 70 Hz even though they can go down lower and listened to music. At first, it was strange because I didn't "hear" the subwoofer, but I know the lower frequencies were there.

I had the same feeling watching the movie. At times I felt like I wasn't getting the same punch, but then the pictures would start to rattle, which didn't happen before. I think this is all good, and is a part of experiencing clean bass.

I have a setup question, however. I understand that when watching a movie than the subwoofer can get information from two sources - the LFE channel and the frequencies stripped off the other speakers - anything below 70 Hz in my case. So what is the frequency range of the LFE channel and where should the LFE LPF be set?

Edit: Any suggestions for a good starting point for the cross-overs for the front speakers (my matching LsiC speaker arrives today)?

LFE channel has a specified cut-off at 120Hz in the standard but in practice it appears very little above 80Hz is ever in the channel... the conventional wisdom says set it to the 120Hz max anyway.

Rythmiks are very articulate and sound tight with music, however movies often have lots of mid-bass effects that you can sense, if that portion of the range is boosted high enough that is... this is not characteristic of a flat response though. You need to first determine the best location for your sub to insure you're not experiencing a null in the mid-bass region, as nulls cannot be compensated for by EQ... even Audyssey can't give you what's missing in a null. So I suggest you try various locations for the sub and evaluate each from your listening position... REW is great for this but you can also just listen to a sweep (10Hz-160Hz) looped to listen for nulls. Once you've eliminated the deepest most serious nulls you can run Audyssey to take care of the peaks, phasing and levels. To exaggerate the mid-bass effects in movies I suggest you experiment with various combinations of the bass extension filter controls (freq and damping). Right now you probably have it set to 14Hz and Hi damping, which for most rooms and set-ups is best for music, however you might find you enjoy movie effects more with less damping and possibly even upping the freq controls... you'll have to experiment a little to find what tickles your fancy.

Always select your cross-over according to where the whole range from an octave above and to an octave below the cross-over sounds smoothest and overall blends best with your mains as heard from the listening position... this will be room specific and speaker placement dependant, it would be a mistake to just blindly go with what works for someone else.

monomer,

Thanks for the response. Unfortunately, I don't have a lot of placement options without a very long rca cable run. Also, the easiest place for the sub has some drawbacks - back against a wall, one side is half-way covered by a wall and the other side faces a speaker and a chair is two feet in front of the sub. I know that down-firing vs side firing isn't suppose to matter much, but it seems like I might loose a lot of sound with the current placement. That said, Audyssey reduced the output by 11.5 dB.

Here is a my current layout in case you would like to comment: Home Theater

Boundaries cause reflections that are so complex it's hard to speculate further than just some generalizations about their effects on a sub's FR performance, so much so that trial-n-error is really the only way to decide on an optimal placement for the sub with respect to a given listening position(s). Sub placement can easily make or break how well a sub will sound in a particular room and set-up. Basically, this is the routine I'd recommend... Run Audyssey to set the levels, then turn off the EQing done by Audyssey or set it to manual and adjust to flat. Next, play a looped sweep 10Hz-160Hz (with the sub running solo) and listen from your favored listening spot(s) and only pay attention to the nulls (you can employ an SPL meter to give you a quantitative visual for verification or simply trusting in your ears can also work well)... Audyssey will attenuate the peaks for you later so don't worry about them at this point. Try this again and again at different sub locations (as many as your layout or the wife will reasonably allow... usually that's only 3 or 4 posibilities for most of us married guys). Then select the position that has the fewest and least serious nulls... under no circumstances should you allow a complete null to exist, you must find a better position for the sub otherwise you will always find it lacking and forever be disappointed... but you cannot blame the sub because its caused merely from poor placement. Remember another alternative is to rearrange the furniture to obtain a different listening position(s)... the nulls will change as this works just like moving the sub. Finally once you've found the spot with the least offensive nulls, THEN run Audyssey again (with all speakers running of course) for phasing and EQing (attenuation of the peaks) and after that it will be sounding the best from your listening position(s) that it can, given your situation. NOW if you want more mid-bass kick for movie effects you can try adjusting the bass extension filter controls to obtain your desired mid-bass boost for the movies.

I do have a SPL meter and I'll check Zune for a sweep pattern (is there another source to download from?).

How careful do I need to be? The Rythmik site talks about a 1/3 duty cycle during break-in.

You will be calibrating at approximately at 75dB or there 'bouts... how hard will that push the sub will depend upon the size and characteristics of your room. I will suggest that if you don't have the sub's gain past 11 o'clock and your AVR ends up at between -5dB and +5dB after Audyssey you should be alright... but really you should probably check with Brian on this first and see what he says. There are a number of places to get free sweeps and tone generators from... I don't really have the time right now to find and post the links but if you do a web search you shouldn't have any problem finding them (I personally haven't used sweeps in a couple of years since I use REW to evaluate FR and more). Later tonight if you haven't been able to locate any sweeps I'll do the leg work and get you a link or two.

Same with my F15, Audyssey reports mine about a foot closer than actual.

I understand that. Sometimes there are devices in the signal chain which introduce delay (like EQ1, Antimode) or some processing going on which does the same thing. As such, if anything the distance could be further than actual.

But closer than actual? This means the signal is reaching faster (which seems impossible). Indeed I asked this in the Audyssey thread and the replies all indicated that distances closer than actual are an anomaly.

Anyway, in the end I manually set the distance to actual (which is what was recommended in the thread).

I found a couple of sweeps and will run them over the weekend. I assume one show play them without the other speakers, which would mean playing them in stereo with the right and left speaker disconnected?

Yes, I believe that is best. My reasoning is that in your search for a best sub position you are evaluating the nulls within the freq range of the sweep and you don't want to confound your results with phasing issues at the cross-over with the mains... since the sub will be moved around this changes phasing and you have no idea what your final cross-over (range) will be. Its best to just hear the sub across its intended range of freqs and evaluate its position based upon the nulls you (don't) hear within that range. THEN later, after you've found that best position for the sub (in relation to your listening position(s)), Audyssey can determine the correct phasing (remember to leave the sub's phase at 0 the whole time) and then you can evaluated various cross-overs freqs by more trial-n-error using the sweep but this time with all the speakers and cross-overs in effect. If you've never done this sort of thing before be prepared for an eye-opener (or should that be an ear-opener?)... you'll be surprised at just how much the volume will change over that freq range, and in some cases you may actually hear the sound completely fade out and disappear then slowly return again (a complete null) as the sweep goes through the frequencies. I did this for the first time about 9 years ago and ever since then have been a big believer in careful sub/listener placements and employing acoustical room treatments... of course Audyssey (and the like) have made the job lots easier. Good luck this weekend! have fun!

I've owned both subs and given your priorities (detail and musicality) I would say yes-A Rhythmik will be a step up from a MFW-15.

Eric

I had this combination last year (pair of D15se) and it was easily one of the best speaker-sub combos I've owned. Audyssey was able to integrate the two pairs flawlessly so they sounded like one full range system.

Eric

You can place them a few inches apart. I recommend against puting them feet apart.

"Closer than actual" means it will add delay to the signal to compensate for the shorter travel time for shorter distance. That is most likely with very large front speaker such that their phase shift at the xover point is almost zero. Sometimes software does make mistakes. So basic understanding of phase alignment and delay/distance adjustment is very helpful.

Most people intuitively think LFE is an independent channel. It is not technically. The best case to explain this is the ending credit sound tracks of Fast and Furious 2. It is so good that I bought a CD sound track and completely disappointed. It simply does not have enough amount of clean bass energy recorded on the CD. It completely makes sense from dynamic range point of view. In CD, there is only 16bit resolution. If that entire resolution is occupied by the slow moving bass signal, there wouldn't be room left for other music signals. Since hearing sensitivity is very low at low bass, that can take away significant dynamic range. So LFE comes into play. Signals below a particular frequency (for instance 120hz) are filtered and put in a single LFE channel. During playback, LFE is actually boosted by 12db (or full 2 bits). In other words, one can imagine the original sound recording is recorded in at least 18bits. Filter out say 120hz and below and the remaining should not exceed 16bit resolution and can be recorded in 16bits for front left and right. The LFE is then reduce by 12db (or reduced by 2 bits) so that it can also be recorded in 16bits. The advantage is when the signal is reconstructed, we want to get the 18bit resolution back with a clear bass reproduction. But literally it is same principle as xover design. it shows the LFE channel should be added back to their original channels. Unfortunately, it is impossible to encode which signal is from which channel in LFE. So most 5.1 decoding method add LFE to both front left and right channels. Then do the filtering again for subwoofer channel output. In order to avoid extra signal leaking from left channel to right and vice versa after decoding, the movie company should keep their "encoding" xover point for LFE as low as possible, such as 80hz. On the other hand the decoding LFE filtering does not make sense at all. The only possible explanation is as a way to prevent digital noise (because LFE has a very low sampling rate) or other artifacts from entering front channels. In short, one should think of 5.1 or 7.1 as an encoding/decoding method, not as formats directly mapped to 6 or 8 physical channels.

Even though the above is based on music signals, it applies to movies too. Special effects such as explosion and gun shot have high frequency components that need to go to front and rear channels. So put LFE back to their original channel to get a full spectrum special effect is very important. As a result, AVR should first add the LFE signal back to front channels and then do a xover (or bass management) to provide one single SUB output.

Brian -

You're one crazy-smart guy...I'm glad I was pointed to Rythmik so I could order my F12. Can't wait to hear what everyone's been raving about.

Brian,

So what are the chances of an 8" servo sub actually happening? I saw in this thread you basically ruled out any real need in designing a 10."

A "Rythmik F8" is the imaginary subwoofer that my PC music setup is waiting for - a small sealed servo sub that can accurately reproduce the rapid double bass in my music. A guy can dream right...

Some rubber surrounds (for instance, DS1200, and older DS12 and DS15) can develop white powder after some time. DS1500 can too, but less frequent. Please do not use solvent-based cleaning solution, such as alcohol to clean it. That would make it worse. The correct way to clean it is use cleaner designed specific for rubbers or tires. Yes, tires. Tires are made from rubber. Please use a small piece of paper towel damped with moderate amount of cleaning liquid and carefully apply it to surround only so that it does not get onto the enclosure part or the metal cone part. Tire cleaner is a bit oily.

I love the look of the D15SE although, if they were available in something like black stained oak it would work out better for me. I want to use them as end tables with a fabricated flat surface of some sort, on top. HG black isn't the end of the world, they certainly look great. My bigger concern is how these things dig for home theater. Visceral impact is a must. I'm always leery of sealed subs for HT only. The dimensions are perfect for end tables! My room is in a sealed basement. I had an SVS PB2+ for years. Subless at the moment. I'd like to hear some comments from D15SE owners on how well this sub performs in low extension. Thanks.

1) shipping delay:
I have to apologize for the customers whose sub delivery got delayed this week. I was trying to finish a few tasks so that my suppliers can get them done before their upcoming 2 weeks break starting Feb 7th. If I missed the deadline, the whole shipment will be delay by at least 2 weeks and more likely 3 weeks.

2) availability
In terms of enclosure availability, I am basically out of enclosures and drivers to build F12 subwoofers. Both of them will be available in 6 weeks. Also I am out of black oak F15 enclosures. Black matte F15's are available.

3) custom veneer option
If anyone would like to get custom wood veneer, it is possible to strip off existing veneer of F12 and F15 and put on custom wood veneer. I have a guy in Austin (Hank is his first name) that can do custom wood veneer. Currently we have F12 and F15 enclosure available for that. The final cost with custom wood veneer is about $150 more expensive (varied by wood selection) than a standard veneer enclosure. That brings it to the same ballpark as "SE" finish.

4) price adjustment
F12SE and F15SE will be priced $150 more than their regular veneer counterpart to better reflect their true cost. So F12SE will be $949 starting with new shipment next month and F15SE is already priced as $1049.

I have same question...it would be great to hear from some D15SE owner's who use it for HT more.

Dave

I found the following sweep in wav format: 20, 25, 31.5, 40, 50, 63, 80, 100, 125 Hz.

I ripped them with Zune and downloaded to my Zune HD. When I first ran them, I had a significant drop at 50 Hz, but them I realized that I had my Polk Lsi15's running. I unplugged those and the drop mostly went away. So I went in the receiver's setup (Onkyo 807) and upped the cross-over to 80 Hz (although the LSi's do a good job of mid-bass). Unfortunately, that didn't keep the Lsi's from playing lower that 80Hz - it seemed to raise the HPF, but not to 80Hz. I'll play some more today, but right now I am low at 20Hz and pretty flat from 25 Hz up to around 60Hz.

I just got my D15SE, but am still setting it up so it is too early to comment. I will say that it is a good looking sub, was packaged very well such that it arrived without a scratch.

Yeah, it's too bad the smallest is 12" (which I have and love in my HT/5.1 music zone).

I think a F10SE would find itself in many living room 2.1 systems (I'd buy one today, heck I'd pre-order one today if Brian said "sure, I'll start the design today"),

and a F8 in veneer would be the MOST popular sub for office 2.1 systems (I'd buy one of these today too).