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Official Rythmik Audio Subwoofer thread - Page 441

post #13201 of 15160
Got my UMIK-1, took my first set measurements. I had some issues with calibrating the SPL but I think the measurments are still valid.

Right sub on, EQ off


Left sub on, EQ off


Both subs on, EQ off


Both subs on, EQ on



Results were fairly similar to what the REW simulator gave. Seems like I have a dip around 40hz. So now I have justification to add a third FV15HP biggrin.gif
post #13202 of 15160
Couple tips. Start you measurement at minimum of 5hz.

When showing a graph make sure the y axis is in 5db increments. It will help see what the results are smile.gif

Also set horizontal axis from 5hz to 300hz

With that said it looks like you are very flat to 10hz and below which is fantastic!!
post #13203 of 15160
I like the extension you're getting. Very nice.

The original readings made with our two FV15HPs, have an Anti-Mode 8033S II in the subwoofer chain (after Audyssey) and there's a noticeable drop in the graph, starting at 20Hz. Yours doesn't start until after 10Hz. According to your graph, with the Anti-Mode out of the chain, hopefully I'll see a major drop in measured response extension to where the sub is expected to perform, down to 12Hz before experiencing drop off.
post #13204 of 15160
Quote:
Originally Posted by ahmedreda View Post

Seems like I have a dip around 40hz. So now I have justification to add a third FV15HP biggrin.gif
Do you have a room dimension that is roughly 14 feet, give or take 6 inches?
post #13205 of 15160
It is about 12-12.5 feet. The dip is around 45hz.
Quote:
Originally Posted by sdurani View Post

Do you have a room dimension that is roughly 14 feet, give or take 6 inches?
post #13206 of 15160
Quote:
Originally Posted by ahmedreda View Post

It is about 12-12.5 feet. The dip is around 45hz.
Can you move one of your subs to the midpoint of that dimension and re-measure?
post #13207 of 15160
I checked the specs for the antimode. It mentions that the frequency range is 5-250Hz but the correction range is 16 - 250 Hz. Do you think it was affecting the frequencies at 16 and below?
Quote:
Originally Posted by BeeMan458 View Post

I like the extension you're getting. Very nice.

The original readings made with our two FV15HPs, have an Anti-Mode 8033S II in the subwoofer chain (after Audyssey) and there's a noticeable drop in the graph, starting at 20Hz. Yours doesn't start until after 10Hz. According to your graph, with the Anti-Mode out of the chain, hopefully I'll see a major drop in measured response extension to where the sub is expected to perform, down to 12Hz before experiencing drop off.
post #13208 of 15160
Not easily! smile.gif Part of the reason I am going with a third sub is that I am so limited with my placement options.
Quote:
Originally Posted by sdurani View Post

Can you move one of your subs to the midpoint of that dimension and re-measure?
post #13209 of 15160
Quote:
Originally Posted by Brian Fineberg View Post

Couple tips. Start you measurement at minimum of 5hz.

When showing a graph make sure the y axis is in 5db increments. It will help see what the results are smile.gif

Also set horizontal axis from 5hz to 300hz

With that said it looks like you are very flat to 10hz and below which is fantastic!!

The Umik-1 has no calibration data below 20hz so not sure how valuable/accurate any data below 20hz would be.
post #13210 of 15160
Quote:
Originally Posted by ahmedreda View Post

I checked the specs for the antimode. It mentions that the frequency range is 5-250Hz but the correction range is 16 - 250 Hz. Do you think it was affecting the frequencies at 16 and below?

Probably not. It probably wouldn't bump those subsonic frequencies.
post #13211 of 15160
The calibration files I used was from cross spectrum. They provide calibration data down to 5Hz. Per Herb, the data should be within 0.5db down to 10Hz and within 2db from 10-5Hz.
Quote:
Originally Posted by aboroth00 View Post

The Umik-1 has no calibration data below 20hz so not sure how valuable/accurate any data below 20hz would be.
post #13212 of 15160
Quote:
Originally Posted by ahmedreda View Post

Not easily! smile.gif Part of the reason I am going with a third sub is that I am so limited with my placement options.
Oh well, good luck with the third sub.
post #13213 of 15160
Quote:
Originally Posted by ahmedreda View Post

The calibration files I used was from cross spectrum. They provide calibration data down to 5Hz. Per Herb, the data should be within 0.5db down to 10Hz and within 2db from 10-5Hz.

Got it. Cross spectrum provides better cal files than Minidsp.
post #13214 of 15160
Quote:
Originally Posted by ahmedreda View Post

Not easily! smile.gif Part of the reason I am going with a third sub is that I am so limited with my placement options.

I've been under the impression it's best to keep the number of subs even, using 2 or 4 vs. 3 if you're trying to spread them out instead of stacking.
post #13215 of 15160
Quote:
Originally Posted by ahmedreda View Post

Not easily! smile.gif Part of the reason I am going with a third sub is that I am so limited with my placement options.

I like your thinking. 1 sub for each possible location. Then you don't have to mess with trial and measure.
post #13216 of 15160
I think I can get away with one sub in the front and one in the back but the front will loose it symmetry. Adding a third sub in the back will be about 3-4 feet away from my seating area so it should balance well with the two subs in the front which are 11 feet away. I should also benefit from the extra tactile feedback from nearfield placement.
Quote:
Originally Posted by Ozzie Isaac View Post

I like your thinking. 1 sub for each possible location. Then you don't have to mess with trial and measure.
post #13217 of 15160
Quote:
Originally Posted by aboroth00 View Post

I've been under the impression it's best to keep the number of subs even, using 2 or 4 vs. 3 if you're trying to spread them out instead of stacking.
3 subs can work fine, using a couple of different placement techniques. You can place all three in null locations to smoothen out the response. Or you can start with one sub and carefully add the other two at different locations to see if the response improves (trial & error).

http://mehlau.net/audio/multisub_geddes/
post #13218 of 15160
Here's a question I've been wondering about. Feel free to give your two cents worth, everybody. Would adding a pair of lesser-performing subs (I have a pair of HSU HRSW10's from the 90's sitting in their shipping cartons) to a pair of Rythmiks, say in the back of the room, bring down the overall quality of the bass reproduction in a system to their level? Logic suggests yes, but I've never heard the results. Has anyone else?
post #13219 of 15160
Ahmedreda,
I believe we have similar subs position being both upfront by main LR. I have about a -3db dip at 33hz with both sub on and Auddessey on (not bad). I am planning to leave the left one up front 5.5' into the 14' room width and move the right one currently about 4' in from right wall to the right back corner (room length is about 19') and do another measurement to see If I have even a better response than a decent one I am currently have. Per Bill and other experts, having two upfront is the worst it can get and they all recommend spread them as far as possible with one in front and one in back. With that being said, I am still trying to improve the response with two subs upfront where they are just to experiment with the Rythmik peq feature (a feature most sub doesn't have) which I think you should try also. I would turn the peq on and play with the gain, frequency, bandwidth settings to get rid of the 3db dip at 33hz and not sure if I would want to apply the peq after or before Auddessey calibration. My thinking is I am trying to apply Rythmik peq to flatten each sub as best as I can individually before running Auddessey which makes it easier for Auddessey to flatten them further together. Does that sound right? Or should I use the post Auddessey calibration measurement of each sub and apply peq individually to flatten the response then using REW to measure both subs? Which way I should proceed? Peq first then Audessey or Auddessey first then peq? I will try both when I am home and have time which is hard to find with three little kids. Thanks.
post #13220 of 15160
Quote:
Originally Posted by ahmedreda View Post

I checked the specs for the antimode. It mentions that the frequency range is 5-250Hz but the correction range is 16 - 250 Hz. Do you think it was affecting the frequencies at 16 and below?

Yes. I'm at 17.5Hz at +/-6dB using Anti-Mode 8033S II and Audyssey XT.



It's a sweet graph but as you can see, the graph doesn't show anything close to the extension you have. In a few days when I get these seasonal allergies under control, I'll give the system a proper measurement using XT32 and no Anti-Mode.

-
Edited by BeeMan458 - 1/14/14 at 11:33pm
post #13221 of 15160
Quote:
Originally Posted by sdurani View Post

3 subs can work fine, using a couple of different placement techniques. You can place all three in null locations to smoothen out the response. Or you can start with one sub and carefully add the other two at different locations to see if the response improves (trial & error).

http://mehlau.net/audio/multisub_geddes/

I don't doubt three subs can work, but with most positioning, the assymmetric placement may not prove best or particularly advantageous. Very valid points about placing the subs in three nulls but its unlikely those three placements would be aesthetically pleasing tongue.gif.
post #13222 of 15160
Quote:
Originally Posted by BeeMan458 View Post

Yes. I'm at 17.5Hz at +/-6dB using Anti-Mode 8033S II and Audyssey XT.



It's a sweet graph but as you can see, the graph doesn't show anything close to the extension you have. In a few days when I get these seasonal allergies under control, I'll give the system a proper measurement using XT32 and no Anti-Mode.

-

Does your mic have a calibration below 20hz? Some don't and the response would just drop off below 20hz even if you have output there. As far as the graph goes, can't tell if there are dips or peaks with the 1/6th smoothing. Looks killer there isn't too many artifacts hidden by the smoothing. Got a waterfall as well?
post #13223 of 15160
Quote:
Originally Posted by aboroth00 View Post

Does your mic have a calibration below 20hz? Some don't and the response would just drop off below 20hz even if you have output there. As far as the graph goes, can't tell if there are dips or peaks with the 1/6th smoothing. Looks killer there isn't too many artifacts hidden by the smoothing. Got a waterfall as well?

I'm not going worry too much until I have a chance to measure the room with XT32 and no Anti-Mode. If need be, I'll purchase a replacement measuring microphone that's certified to the lower octave.

Waterfall: No smoothing:

-
Edited by BeeMan458 - 1/15/14 at 12:06am
post #13224 of 15160
Quote:
Originally Posted by Rythmik View Post

We have a Java scripts helping customers to do the integration (in case customers do not have bass management) : www.rythmikaudio.com/subtuner2.html. The script gives you recommended crossover and phase adjustment based on your driver diameter in your front speakers and whether it is sealed for vented (transmission line is treated same as vented sub). When the script was written, it didn't consider planar speakers, but it is not hard to work around it. Sealed front speakers have 2nd order roll-off, vented front speakers have 4th order roll-off and planar front speakers have 3 order roll-off. So you can try sealed front speaker configuration sealed front speakers first (use 10 diameter) and try vented from speakers. The phase adjustment you need should be somewhere between these two recommended settings. In actual listening test, you can start with the recommended setting and gradually change 1 clock position up or down at a time. When you get the correct alignment, the energy around the crossover point should sound more firmed up.
If you set the crossover knob also at 50hz, then you can true 50hz/24db roll-off. If you move the knob to 32hz, then between 32hz and 50hz and it is still technically 12db. The customers shouldn't be too concerned about the exact corner frequency. Phase alignment is what we need to be concerned with.

Thanks for the detailed answer. Please allow me to continue to probe, for my benefit and hopefully others reading...

Having full range speakers which play flat to 32hz, I am using the Rythmik for true sub bass only. Therefore, I assume I want to set the Rythmik sub XO to 32 or lower. This gives me 12db per roll off with a slight bump at 50hz, but otherwise flat to 20hz (which is thy limit to my SPL meter). If I adjust the phase from 0 to about 90, I definitely get MORE bass at 50. I get too much, wth about a 5 db peak. My assumption is that I do not want this peak, thus I do not want to "firm up" the energy further at the XO. Is my assumption correct, or is there something other tha flat frequency which I should pursue?

For example, at higher frequencies, multiple drivers could measure flat but smear the image. Is this a risk at 50 hz? Should I be concerned both with frequency and timing in the low bass? Is this part of what I am adjusting with the phase knob? If so, do I want to firm it up, and if too high, equalize it back out with the PEQ?
post #13225 of 15160
Yes in my measurement, the two subs the front had almost identical response so no real benefits as far as smoothing goes. Did you try measuring with the EQ off? In my case there is a huge dip without the EQ and it is fairly corrected with the EQ on. I could be wrong but that tells me that a good amount of the amp power is wasted in that correction and that the dip will likely be there at higher volumes. I don't have experience with the rythmik PEQ but there was a discussion about it a while back. May be rcohen or Brian can chime in?
Quote:
Originally Posted by Cowboys View Post

Ahmedreda,
I believe we have similar subs position being both upfront by main LR. I have about a -3db dip at 33hz with both sub on and Auddessey on (not bad). I am planning to leave the left one up front 5.5' into the 14' room width and move the right one currently about 4' in from right wall to the right back corner (room length is about 19') and do another measurement to see If I have even a better response than a decent one I am currently have. Per Bill and other experts, having two upfront is the worst it can get and they all recommend spread them as far as possible with one in front and one in back. With that being said, I am still trying to improve the response with two subs upfront where they are just to experiment with the Rythmik peq feature (a feature most sub doesn't have) which I think you should try also. I would turn the peq on and play with the gain, frequency, bandwidth settings to get rid of the 3db dip at 33hz and not sure if I would want to apply the peq after or before Auddessey calibration. My thinking is I am trying to apply Rythmik peq to flatten each sub as best as I can individually before running Auddessey which makes it easier for Auddessey to flatten them further together. Does that sound right? Or should I use the post Auddessey calibration measurement of each sub and apply peq individually to flatten the response then using REW to measure both subs? Which way I should proceed? Peq first then Audessey or Auddessey first then peq? I will try both when I am home and have time which is hard to find with three little kids. Thanks.
post #13226 of 15160
Quote:
Originally Posted by BDP24 View Post

Here's a question I've been wondering about. Feel free to give your two cents worth, everybody. Would adding a pair of lesser-performing subs (I have a pair of HSU HRSW10's from the 90's sitting in their shipping cartons) to a pair of Rythmiks, say in the back of the room, bring down the overall quality of the bass reproduction in a system to their level? Logic suggests yes, but I've never heard the results. Has anyone else?

I would not go so far as to say they would bring down the quality but they certainly could. Matching gain/phase response over frequency could be a real challenge. The few times I have tried to integrate dissimilar subs was very painful, enough so that I will always use the same if at all possible. If I pick up another pair of subs it will be two more F12's to match my main subs even though I could actually fit F15's in the back of the room. Sort of.
post #13227 of 15160
Quote:
Originally Posted by aboroth00 View Post

Very valid points about placing the subs in three nulls but its unlikely those three placements would be aesthetically pleasing tongue.gif.
Didn't realize you were talking about aesthetics when you said "keep the number of subs even, using 2 or 4 vs. 3".
post #13228 of 15160
Quote:
Originally Posted by ahmedreda View Post

Yes in my measurement, the two subs the front had almost identical response so no real benefits as far as smoothing goes. Did you try measuring with the EQ off? In my case there is a huge dip without the EQ and it is fairly corrected with the EQ on. I could be wrong but that tells me that a good amount of the amp power is wasted in that correction and that the dip will likely be there at higher volumes. I don't have experience with the rythmik PEQ but there was a discussion about it a while back. May be rcohen or Brian can chime in?
I sure did measure each sub and both subs with Auddessey off and on. With Aud off, I also get a big dip at 50 for my left sub, and another big dip about 80 on my right sub but measuring both subs together with aud off helps ALOT flatten those dips out but not completely, hint the reason I am always now recommending at least 2 subs. Turn aud on and it helps a bit with each sub measured separately but when measuring both subs with aud on, it almost completely got rid of the two dips at 50 and 80 but now I got a -3db dip about 33hz. This is why I asked earlier if it is better trying to use Rythmik peq to somewhat get rid of the dips before or after Auddessey calibration. Brian, if you read this, please chime in and suggest or I guest I can try both to see it for myself.
post #13229 of 15160
Quote:
Originally Posted by Cowboys View Post

This is why I asked earlier if it is better trying to use Rythmik peq to somewhat get rid of the dips before or after Auddessey calibration.

After. I played with this point as I was dialing in the new subs with XT and Anti-Mode 8033S II. With the PEQ on, it killed the response. When I turned the PEQ off, everything was normal again.

Another point, do one PED at a time. The furthest from the MLP first. I found that if I PEQ'd the dip on the sub furthest from the MLP, I got the best result but if I did both, the dip stayed. Over the last year, I've learned that peaks and nulls are symbiotic and feed off each other so the counter is to change the settings on the dominant subwoofer and make PEQ changes asymmetrical as opposed to simultaneously equal.
post #13230 of 15160
Ahmedreda,
I know you want to add a third sub to flatten your response and don't want to just move one of your two subs to the back due to symmetry look up front. I cannot add a third sub (wife would just kill me as she thinks an sb12 is too much in our 8000ft^3 living room and I already have two FV15hps in my dedicated 2700ft^3 room). I agree with you that one sub upfront does not look right (at least to us) but here is what I am planning to do with my set up and hopefully getting a better response than both subs up front: move my right sub to the right back corner just right behind my seating area which is about 4' from MLP, move my left sub toward the middle of the room upfront and have my center speaker above it (I am having a small stand that only siting on the two short component racks directly to left and right of the sub so that the center is not sitting directly on the sub and it is raised to my ear level). This way, I still pertain the symmetry look upfront and again I hope for a better response. Perhaps you can also try?
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