Help with in room response (1 x Dayton 18" DIY) - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 21 Old 04-20-2019, 12:01 PM - Thread Starter
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Help with in room response (1 x Dayton 18" DIY)

I have a dayton ref HO18 and removed all eq methods before taking a measurement - can anyone suggest why the response would suddenly drop at around 30hz and then level out (ish) until 15hz where my HPF kicks in? I have mostly had a dip at 30hz before due to the room, but it seems weird why it wouldn't go back up after. the room is approx 1500 cubic feet sealed.

If its just the frequency drop of the driver, i just dont understand why it wouldn't continue dropping rather than a sudden drop and then flatten again, it just seems odd.


Thanks in advance
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post #2 of 21 Old 04-21-2019, 01:39 PM
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I hope someone can help you out on this. I have the same dip. Do you have cement or tile floors by chance? What type of enclosure is the sub in?
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post #3 of 21 Old 04-21-2019, 01:58 PM
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Room gain can start to level off the dip in response, especially in a smaller space. For testing to see if there is a dip caused by filters or some other part of your sub, take a near field measurement close to the sub at a low volume. Too much volume can easily clip the mic. Remember volume does not change the response curve of a sub That should give you a better understanding of the response of the sub vs the response of the sub + room.

Edit: If the posted response looks like the near field response, that indicates the lull is caused by your subwoofer as a system.

If the near field response is much flatter, it is probably the position of the sub in the room. A subwoofer crawl would be in order or consider a second sub.

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post #4 of 21 Old 04-21-2019, 07:17 PM - Thread Starter
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Quote:
Originally Posted by Kameron King View Post
I hope someone can help you out on this. I have the same dip. Do you have cement or tile floors by chance? What type of enclosure is the sub in?
it is an approx 85L Sealed Cabinet with 1000w amp - Carpeted Cement floor

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Originally Posted by Red Five View Post
Room gain can start to level off the dip in response, especially in a smaller space. For testing to see if there is a dip caused by filters or some other part of your sub, take a near field measurement close to the sub at a low volume. Too much volume can easily clip the mic. Remember volume does not change the response curve of a sub That should give you a better understanding of the response of the sub vs the response of the sub + room.

Edit: If the posted response looks like the near field response, that indicates the lull is caused by your subwoofer as a system.

If the near field response is much flatter, it is probably the position of the sub in the room. A subwoofer crawl would be in order or consider a second sub.

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Thanks for the reply, do you recommend reducing the volume then to check the true response of the sub? I can take a nearfield measurement once everyone goes out, Sub crawl is kinda outta the question as it about 130 lbs and i have a back problem. Positioning options are rather limited too unfortunately.

I will post the nearfield graph once i get a free house. thanks again
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post #5 of 21 Old 04-21-2019, 07:50 PM
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It's been a long time since I played around with REW. If I recall there are directions for setting the level on the UMIK mic. Instead of follow directions for the MLP you would put the mic close to the sub and then adjust so it comes in close to 75db. It will not take much power if it is a ft or less off the cone. There will be roll off with a sealed enclosure, but that looks a little steep and sudden at 30Hz.

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post #6 of 21 Old 04-21-2019, 07:57 PM - Thread Starter
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Quote:
Originally Posted by Red Five View Post
It's been a long time since I played around with REW. If I recall there are directions for setting the level on the UMIK mic. Instead of follow directions for the MLP you would put the mic close to the sub and then adjust so it comes in close to 75db. It will not take much power if it is a ft or less off the cone. There will be roll off with a sealed enclosure, but that looks a little steep and sudden at 30Hz.

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Ok, now I get you, setting the levels Im all good with, so Ill do a nearfield measurement and post whats happening, thanks
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post #7 of 21 Old 04-21-2019, 08:41 PM
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Originally Posted by gentlemaniac View Post
Thanks for the reply, do you recommend reducing the volume then to check the true response of the sub? I can take a nearfield measurement once everyone goes out, Sub crawl is kinda outta the question as it about 130 lbs and i have a back problem. Positioning options are rather limited too unfortunately.
fwiw, if you are able to get the sub moved to your listening position, you might be able to do the sub crawl with the mic, with a long enough usb cord... at least get a general idea of where it might work, or even just to verify that the problem could be caused by room location.
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post #8 of 21 Old 04-22-2019, 02:51 AM - Thread Starter
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Originally Posted by osv1 View Post
fwiw, if you are able to get the sub moved to your listening position, you might be able to do the sub crawl with the mic, with a long enough usb cord... at least get a general idea of where it might work, or even just to verify that the problem could be caused by room location.
Really cant be moving this thing around unless absolutely necessary, I will be in agony for about a week if I do. I could always measure the resposne at various places within the room though to see how it changes? Could be an idea.
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post #9 of 21 Old 04-22-2019, 03:02 PM - Thread Starter
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an additional question regarding the same problem when Im using the EQ option in REW is that when I try to create the filters for my miniDSP 2x4, is that it doesn't apply any boost what so ever to the lower frequencies and just cuts down the higher freq's (above 30) even though the target line runs between them. Does anybody have an idea why it may do that?
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post #10 of 21 Old 04-23-2019, 06:43 AM - Thread Starter
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So took several response measurements today with the mic in the same position but changing the phase,

The first image is the best response I received with the mic directly under the Sub (I took about 6 different measurements though)

The second image is a collaboration of measurements taken at MLP with different phases, all showing the 30 hz lull that im experiencing.

These measurements were taken with no EQ whatsoever
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post #11 of 21 Old 04-24-2019, 09:03 AM - Thread Starter
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OK, so looks like the answer to this query is that my room hates my Main Listening Position. I took measurements at various places in the room (as loaded below) and you guessed it, the response changes and is actually better on the couch on the far side of the room.

The worst thing is, moving my sub 2 feet made no difference at all, and moving my sofa forward would've also made no difference so im between a rock and a hard place. Going to have to EQ like mad until I can add another sub
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post #12 of 21 Old 04-24-2019, 09:33 AM
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Is there a boundary such as a wall that you can try firing the driver side into and then get the sub close to that boundary? Changing the direction in which the sub is pointed sometimes helps. It can go well or it can do the exact opposite. It might be worth a shot since your locations are limited.

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post #13 of 21 Old 04-24-2019, 10:28 AM - Thread Starter
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Its a down firing sub, but i suppose i could remove the feet and lay it on its back so to speak and see how that goes. Only problem is my 2 year old would probably try using it to climb on and damage the driver
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post #14 of 21 Old 04-24-2019, 04:29 PM
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Toddler, cone visibility, back pain, I think we are in some kind of club Since it is down firing turning it has a low probability of success. Is it the 460HO? The UMs drop in price frequently, not so sure about the 460s. Picking up a second one appears to be the best option.

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post #15 of 21 Old 04-25-2019, 06:03 AM - Thread Starter
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Quote:
Originally Posted by Red Five View Post
Toddler, cone visibility, back pain, I think we are in some kind of club Since it is down firing turning it has a low probability of success. Is it the 460HO? The UMs drop in price frequently, not so sure about the 460s. Picking up a second one appears to be the best option.

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Don't suppose you are in the awful room response and stuck with only one sub club too huh?

Yes its a Dayton 460HO
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post #16 of 21 Old 04-25-2019, 06:19 AM
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I have one sub, but the response seems pretty good so I am fortunate. I do not have a mic for measuring right now, I am trusting my ears and YPAO. Have you gone for a read through this guide - https://www.avsforum.com/forum/113-s...eferences.html ?

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post #17 of 21 Old 04-26-2019, 07:27 AM - Thread Starter
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Thanks for the link, I've had a quick browse but not an in depth read, but it looks interesting.

To update, I have tried the sub facing most feasible directions, even toddler hazardous ones and nothing improves it, so my options are;

Add another sub (Difficult to get clearance from WAF - But maybe could do custom nearfield hidden box with 2 x 12's in it) - How would 2 Dayton Ref 12" Subs do with 1000w RMS @ 4 ohm
Change to a Ported Cabinet (to boost lower frequencies)
Relocate sub woofer (Also quite awkward as not many other spaces in room - but may be a possibility)
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post #18 of 21 Old 04-26-2019, 09:40 AM
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Concerning the ported design, when you have a sub with a null throwing more output from that spot works very much like multiplying by zero, so probably not the best path. Have you seen the JBLs that keep going on sale? If you can find a way to load a few near field it is a compelling option and cheap too or even forget near field and pickup a box that holds four. Roughly 3 = one UM18. Part of me is tempted to eventually build a riser sub up firing beneath the couch

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post #19 of 21 Old 04-26-2019, 12:31 PM
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That "W" shape in the first posted response curve screams phase issue to me. If switching 180 degrees doesn't work, try adjusting delay in your DSP. Start with 1 m/s of delay for each foot away the sub is from the listening position (8 ft. = 8 m/s) to get you in the ballpark, and work up and down from there.

A second sub will improve everything dramatically.

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post #20 of 21 Old 04-26-2019, 05:16 PM - Thread Starter
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That "W" shape in the first posted response curve screams phase issue to me. If switching 180 degrees doesn't work, try adjusting delay in your DSP. Start with 1 m/s of delay for each foot away the sub is from the listening position (8 ft. = 8 m/s) to get you in the ballpark, and work up and down from there.

A second sub will improve everything dramatically.
Thanks for the tip, My crossover is at 80 hz so obviously this doesn't prove for great integration between sub and speakers, but that measurement is with no EQ applied at all. I don't recall it being there with Audyssey on but I shall have a re-measure once everything is re-calibrated.
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post #21 of 21 Old 04-26-2019, 10:25 PM
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I would also EQ 33-70 Hz down to match the response below 33 Hz. Once flat, you can crank it a little.

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