Help calibrating uls-15 dual drive

[sethhobrin]

Hey Pete, wondering if you and/or other could offer some advise.

I am running the ULS-15 dual drive. I just upgraded my reciever to the Onkyo 5507 prepro which has 2 subwoofer outs and the audyssey calibration calibrates them both independantly.

What is your thoughts on running one of the 2 subs at 180 phase out of step with the other sub? I seem to get much more base in my room that way.

Or should I just be setting them both to 0 and letting Audyssey do its thing for both subs?

Sorry for lack of pics but it is an open concept first floor to living room, dining, room, family room, kitchen. no cathedral ceilings.

1 sub is in front left corner. the other sub is in the middle of the side wall to an adjoining room pointing in to the same room. I am not able to relocate the subs.

[Pete_Hsu]

Hi Seth,

When your two subs are separated, running them both at 0 degrees (or both at 180 degrees) seems to result in the two subs being out of phase with each other. So by all means set one sub to 180 degrees, and then run the Audyssey calibration. Most likely Audyssey will look at the overall subwoofer response, and attempt to set the subwoofers in phase with the main speakers.

Thanks

Sincerely,

[JerryMeeker]

I recently installed the ULS-15 dual-drive as well, and am not sure I agree with this response. I spent over a week experimenting with placement, crossover settings, and Audyssey room correction. Here are several recommendations that helped me achieve an almost perfect integration in my listening area:

1. Make sure the two ULS-15's are EXACTLY the same distance from the primary listening area. Why? Because Audyssey has only one subwoofer equalization channel, so there is only one possible delay (distance) setting. If your subs are not equidistant, then the sound from one sub reaches your ears before the other, causing all sorts of issues. This restriction can be difficult to achieve, but is very important.

2. Before running Audyssey, make sure you set the level on each sub independently, using a SPL meter. This ensures that Audyssey "hears" the same level from each sub during the calibration. See my posting in the tuning folder for additional guidelines on Audyssey.

3. If you have been using a bass equalization system, get rid of it--it only screws up the Audyssey correction. I had been using a Velodyne SMS-1, and it's now in a box in the closet, and my results are much better. This tip may not apply to you.

4. And finally, make sure you measure the exact physical distance between the sub (taken at the center of the driver) to the primary listening area (at ear level). After running Audyssey, check the calculated distance. If the calculated distance is greater than the actual distance, make no change. However, in some cases, the calculated distance is slightly less than the actual distance. In this case, Audyssey recommends manually adjusting the distance setting for the sub so that it matches the actual distance. For some reason, my calculated distance was approximately one foot smaller than the actual distance.

If you follow these guidelines, you should not perceive that one of the ULS-15's is louder than the other (since you have level-set them), so keeping the phase switches the same would be recommended. Just my opinion. Feedback would be welcome.

BTW, the ULS-15 dual-drive sounds great in my system!


EDIT: Sorry, after re-reading your post, I see that your Audyssey calibrates two subs independently. The recommendation for equidistant placement may not apply to you.

[Pete_Hsu]

To me it would seem that one would want to get as flat a response as possible before running Audyssey. So that is why I feel it is important to have the subs in phase with each other before using any auto-eq. In general I agree that it is ideal to have the two subs equidistant from the main listening position, but I'm not sure this will be possible in seth's case due to the placement restrictions.

[JerryMeeker]

I agree with you completely, Pete. However, the instructions for determining the proper setting of the phase switch are somewhat vague. There are two statements:

- The bass in the crossover region may be smoother...."

- The position that gives a fuller bass...is the correct one."

What are the methods by which we can determine "smoother" and "fuller"? I believe we have agreed on the process to set the gain control on each subwoofer separately to achieve matched output volumes. What are other tests that can be performed? Are you suggesting measuring the output levels at multiple frequencies using the test CD and an SPL, switching the phase switch for each measurement? Perhaps a more specific recommendation would be useful for those of us looking for the sweet spot.

As always, your feedback is valued.

[Bill Mitchell]

Jerry, I think Pete's first response was specific to Seth's comment that he perceived more bass when the two subs had the phase switch in opposite positions, and not intended as a general recommendation.

I do find your list fairly complete. For a single sub, the low investment technique is to use the warble tone on the Hsu test disk at the crossover and see which phase gives the highest volume, relative to the mains. I would think that, for dual subs, one could do this in two steps. First, with the two subs together and the mains disconnected, see whether the volume is higher with the switches set identically or inverted to each other. Second, with the two subs now more or less in phase at the crossover, combine them with the mains and see whether keeping the switches in one position or inverting both together yields the better result.

As you noticed, with Seth's Onkyo having independent sub trims, one would want to evaluate the subs' phase settings only after letting Audyssey calculate the distances.

If one has a Radio Shack SPL meter, some cables, and a computer sound card that accepts line level inputs, one can perform a broader evaluation using software like Room EQ Wizard to graph the frequency response and see which combination of phase switches gives the flatter overall response before Audyssey, then run Audyssey equalization. This is certainly a less time consuming approach than exhaustively trying every combination of phase switches, running Audyssey setup, and measuring the result to see which the Onkyo handles better with its independent sub equalization.

[Pete_Hsu]

That is correct Bill.

Basically, with two subwoofers, setting phase is a two step process: Step 1: Set each subwoofer in phase with each other. Start with one subwoofer on, play a 50Hz test tone, and then turn the second subwoofer on. If the two subs are in phase, then the output should increase. Step 2: Set the subwoofers in phase with the main speakers. Invert the phase on both subwoofers to see if that results in a flatter frequency response near the crossover frequency. One can either do this manually using an SPL meter and test tone CD, or use an Auto-EQ.

Jerry, I have to commend you on all the great work you did to set up your system, well done :)

Sincerely,

[hjones4841]

To me it would seem that one would want to get as flat a response as possible before running Audyssey.

Pete, when I set mine up I tried flattening the response using a BFD before running Audyssey and got some rather strange looking REW plots. For me, running Audyssey first, then smoothing with the BFD produced the best results. Others have found best results the other way around.

That said, finding the best place first for the subs in the room before running Audyssey is certainly what to do to reduce the "work" Audyssey has to do to make corrections.

Perhaps this is a place to recommend REW, a free download from hometheathershack.com, for setting up subs. It certainly eliminates a lot of guesswork. All the instructions for using it are over at the 'shack's website.

[JerryMeeker]

Thanks for the kind words, Pete. All this discussion regarding the proper setting of the phase switch made me do some research and then re-check my phase settings. I found an interesting recommendation from Robert Harley, a well-known audio expert.

After running the phase test, I discovered that the proper phase setting on my ULS-15's is 180 degrees, not zero degrees! After making this change and re-running Audyssey, I'm still trying to figure out whether I hear any difference. :confused:

If you are interested in the method, here is the excerpt from

THE PERFECTVISION GUIDE TO SURROUND SOUND SPEAKER SYSTEMS, “How to Position and Set Up a Subwoofer”, by Robert Harley:
But there’s a much more precise way of setting the phase control that guarantees perfect phase alignment between the subwoofer and main speakers. First, reverse the connections on your main loudspeakers so that the black speaker wire goes to the speaker’s red terminal, and the red speaker wire goes to the speaker’s black terminal. Do this with both speakers. Now, from a test CD that includes pure test tones, select the track whose frequency is the same as the subwoofer’s crossover frequency. Sit in the listening position and have a friend rotate the subwoofer’s phase control until you hear the least amount of bass. The subwoofer’s phase control is now set perfectly. Return your speaker connections to their previous(correct) positions: red to red, black to black.

Here’s what’s happening when you follow this procedure. By reversing the polarity of the main speakers, you’re putting them out of phase with the subwoofer. When you play a test signal whose frequency is the same as the subwoofer’s crossover point, both the sub and the main speakers will be reproducing that frequency. You’ll hear minimum bass when the waves from the main speakers and subwoofers are maximally out of phase. That is, when the main speaker’s cone is moving in, the subwoofer’s cone is moving out. The two out-of-phase waves cancel each other, producing very little bass. Now, when you return your loudspeakers to their proper connection (putting them back
in-phase with the subwoofer), they will be maximally in-phase with the subwoofer. This is the most accurate method of setting a subwoofer’s phase control. Unless you move the subwoofer or main speakers, you need to perform this exercise only once.

I used the Hsu test CD, track 15 (63 Hz), because my crossover is set to 60 Hz. Using an SPL meter, the bass when the phase was set to zero degrees was significantly louder than when set to 180 degrees, which suggests that 180 degrees is the right setting in my situation.

What do you think?

[cacihome]

That in the end, what matters is what you like...

[Pete_Hsu]

Hi Harry,

Pete, when I set mine up I tried flattening the response using a BFD before running Audyssey and got some rather strange looking REW plots. For me, running Audyssey first, then smoothing with the BFD produced the best results. Others have found best results the other way around.

That said, finding the best place first for the subs in the room before running Audyssey is certainly what to do to reduce the "work" Audyssey has to do to make corrections.

Perhaps this is a place to recommend REW, a free download from hometheathershack.com, for setting up subs. It certainly eliminates a lot of guesswork. All the instructions for using it are over at the 'shack's website.

What I meant is that one should try to achieve as flat a response as possible before using any form of EQ. So that is why placement and phase becomes so important, especially with multiple subwoofers.

Sincerely,

[Pete_Hsu]

Hi Jerry,

Thanks for the kind words, Pete. All this discussion regarding the proper setting of the phase switch made me do some research and then re-check my phase settings. I found an interesting recommendation from Robert Harley, a well-known audio expert.

After running the phase test, I discovered that the proper phase setting on my ULS-15's is 180 degrees, not zero degrees! After making this change and re-running Audyssey, I'm still trying to figure out whether I hear any difference. :confused:

If you are interested in the method, here is the excerpt from

THE PERFECTVISION GUIDE TO SURROUND SOUND SPEAKER SYSTEMS, “How to Position and Set Up a Subwoofer”, by Robert Harley:
But there’s a much more precise way of setting the phase control that guarantees perfect phase alignment between the subwoofer and main speakers. First, reverse the connections on your main loudspeakers so that the black speaker wire goes to the speaker’s red terminal, and the red speaker wire goes to the speaker’s black terminal. Do this with both speakers. Now, from a test CD that includes pure test tones, select the track whose frequency is the same as the subwoofer’s crossover frequency. Sit in the listening position and have a friend rotate the subwoofer’s phase control until you hear the least amount of bass. The subwoofer’s phase control is now set perfectly. Return your speaker connections to their previous(correct) positions: red to red, black to black.

Here’s what’s happening when you follow this procedure. By reversing the polarity of the main speakers, you’re putting them out of phase with the subwoofer. When you play a test signal whose frequency is the same as the subwoofer’s crossover point, both the sub and the main speakers will be reproducing that frequency. You’ll hear minimum bass when the waves from the main speakers and subwoofers are maximally out of phase. That is, when the main speaker’s cone is moving in, the subwoofer’s cone is moving out. The two out-of-phase waves cancel each other, producing very little bass. Now, when you return your loudspeakers to their proper connection (putting them back
in-phase with the subwoofer), they will be maximally in-phase with the subwoofer. This is the most accurate method of setting a subwoofer’s phase control. Unless you move the subwoofer or main speakers, you need to perform this exercise only once.

I used the Hsu test CD, track 15 (63 Hz), because my crossover is set to 60 Hz. Using an SPL meter, the bass when the phase was set to zero degrees was significantly louder than when set to 180 degrees, which suggests that 180 degrees is the right setting in my situation.

What do you think?


What he is saying is fine. He is first wiring the main speakers with inverted polarity, then setting the subwoofer phase switch so that subwoofer is out of phase with the mains, and then wiring the main speakers with proper non-inverted polarity again.

An alternate (and perhaps easier) way to do this is to wire the main speakers with proper non-inverted polarity, and then simply experiment by inverting the subwoofer's phase switch to see if subwoofer output increases or decreases near the crossover frequency.

Sincerely,

[JerryMeeker]

Pete,
First of all, I want to thank you for your feedback, and your patience with my experimentation with the sub phase setting. I hope others are benefitting from this discussion as well.

OK, based on your last recommendation, I experimented with leaving the main speakers properly wired, toggling the phase switches on the ULS-15’s, and measuring the output levels with my SPL meter. I would like to share the results and then ask one last time for your guidance.

Prior to running the tests, I turned all Audyssey room correction off, including Dynamic EQ and Dynamic Volume. The two subs are level-matched (not gain-matched). The left sub is in a room corner, 6” from both the back and the side walls. The right sub is 6” from the back wall, but 4’ from the side wall (my primary listening spot is off to the left of room center, approximately 1/3 of the room width). Both subs are exactly the same distance from the primary listening spot (14’2”). Recall in previous conversations that Audyssey requires the subs to be equidistant.

The main left and right speakers are set to “small”, with the crossover at 60Hz. These are tower speakers with two 6 ½ bass drivers rated flat to 40Hz (+/- 3db). For the test, I am using the Hsu CD, track 15 (63Hz). Here are the test results:

Test 1: Left sub on, right sub off.

- Phase at 0, SPL measures 78db.
- Phase at 180, SPL measures 83db (best).

Test 2: Left sub off, right sub on:

- Phase at 0, SPL measures 78db (best).
- Phase at 180, SPL measures 77db.

Test 3: Both subs on:

- Left sub phase at 0, right sub phase at 0, SPL measures 79db.
- Left sub phase at 0, right sub phase at 180, SPL measures 76db.
- Left sub phase at 180, right sub phase at 180, SPL measures 83db (tie for best).
- Left sub phase at 180, right sub phase at 0, SPL measures 83db (tie for best).

The results seem to suggest that the last two settings, which yielded SPL measurements of 83, are probably the better settings. Questions for you: why would I be getting the same readings with the right sub set at 0 or 180? Given that both setting product the same results, which of the two settings would you recommend? I am sticking with both subs set for 180 right now, which is the result a came up with several days ago. Can one sub be at 180 and one sub at 0?

By the way, since I changed the subs to 180, the clarity of the dialog coming from the center channel is noticeably better—more open, less tubby. I’m very pleased with this result.

Regards--Jerry

[Pete_Hsu]

Hi Jerry,

Thanks for sharing those measurements. Is the SPL meter kept at the listening position, ear level, at a fixed location (with C weighting and "Slow" settings)? Could you describe in more detail what procedure was used to level match each subwoofer? Also, if you have time, it would be great if you could you post the SPL with each of those phase combinations @ 20/25/31.5/40/50/63/80Hz. Looking at the whole deep bass and mid-bass response will be very helpful in understanding what is happening. With just one test frequency, it is difficult to know exactly what is best. That said, it looks like the subwoofer in the front left corner is the one that is contributing by far the most towards total sound pressure level at 63Hz, and that is why you see little to no increase when turning on the second subwoofer. Clearly it seems best to have the front left subwoofer set to phase 180.

Sincerely,

[JerryMeeker]

I tried both "level setting" and "gain setting". By level setting, I mean placing the SPL at the primary listening point and playing the test tone from the AVR that is used to set speaker levels. I set the gain control on each sub separately to produce the same levels on the SPL.

You described the procedure to gain set the subs in a previous thread, which I have tried as well. In my case, the gain settings on the two subs are approximately the same regardless of which procedure I use, so I am assuming it doesn't play that important a role.

Back to the measurements I provided earlier in this thread--I subsequently performed several listening tests with familiar music sources with good bass. I immediately noticed a better, more defined bass response with the Left 180, Right 0 setting.

I then re-ran Audyssey and, for the first time, Audyssey calculated the sub's distance correctly (previous calculated distances were approximately 1 foot off). So, this leads me to believe the phase setting is now correct. I am very pleased with the sound! :D

[Pete_Hsu]

Good deal Jerry! I agree that, based on the measurements above and based on your own listening impressions, left at 180 and right at 0 seems to be the best combination.

It is unclear to me what exactly what frequency (or frequencies) is being sent from the receiver, so for level matching I usually just use the test tone CD.

I wouldn't sweat the details too much now, because I think you have arrived at a great result :)

Sincerely,