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Old 7th November 2017, 08:59 PM   #21
umut1001 is offline umut1001  Europe
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Sorry it is measured with my asus notebooks microphone not with a measuring microphone yet(will buy asap).Looking forward to TV.Not pointing up to ceiling.It is parallel to ground
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Old 7th November 2017, 09:12 PM   #22
DonVK is offline DonVK  Canada
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It's probably an electret mic, limited to voice band, so pointing up (mic surface parallel to ground) is the right way, preferable the screen can fold nearly out of the way (flatish).

For this kind of measurement, you don't need a lab grade mic. You're only looking for LF room nulls / modes and your laptop is a very small compared to their wavelength. It will work.

Last edited by DonVK; 7th November 2017 at 09:14 PM. Reason: parallel
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Old 7th November 2017, 10:31 PM   #23
bentoronto is offline bentoronto  Canada
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subwoofer position
Quote:
Originally Posted by umut1001 View Post
I have just checked Room simulation tool.I also simulated with 2 subwoofers but it seems it does not help much...


It seems ultra flat response drivers not necessary right?Maybe bad response drivers are better and corrected by room Room makes everything bad
Web is full of room mode calculators. I'm sure they would be helpful if you had a concrete room with no furniture in it. My experience too.

Some truth to what you say about speakers and rooms. Recently got pilloried in another thread when I said the key feature of a crossover is that you can fiddle with it once your "perfect" speaker is placed in your imperfect room. Of course, that requires that you are bi-amped and DSP'ed, because that's the only way to have much control over your listening experience.

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Old 7th November 2017, 10:48 PM   #24
chris661 is offline chris661  United Kingdom
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Originally Posted by bentoronto View Post
Very nice of you to want to educate me more on the frequency compass. I wish I could educate you more on (1) hearing perception and (2) the content of recordings. A good place for you to start is the recent thread about how low do you need to go.
Ben, you're quite welcome.

I do believe most of us here can, in fact, tell when there's a 40dB hole in the middle of the LF region, and I'd be more than happy to point to an exceptionally large number of recordings that would suffer from having a frequency response like the one shown.

AC/DC's Back In Black, for instance, has a lot of the kick at 70Hz (-35dB), but the 41Hz content averages a couple of dB higher than the 1kHz content (-48dB and -51dB respectively). Figures quoted are from Audacity's spectrum analyser.

That's not a track that's got a reputation for being bass-heavy. It isn't dubstep or synthesised. It's good ol' rock 'n' roll.

If you like, I can make a quick loop-through recording of a few tracks with and without the 40dB hole in the LF, so we can do some ABX testing and find out just how many of the members on our forum can tell the difference.


The other day, I was doing a gig with a live rock band. 2x electric guitars, drums, bass, keys, and 4x vocals. According to the RTA on the mixing desk, we were putting out plenty of bass down to 50Hz.
Again, losing 40dB of output in that region would be more than noticeable. It'd be outright objectionable.


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Old 7th November 2017, 11:05 PM   #25
bentoronto is offline bentoronto  Canada
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and I'd be more than happy to point to an exceptionally large number of recordings that would suffer from having a frequency response like the one shown.
Deceitful to quote me out of context. In that same post said "No, I wasn't advocating a 70 Hz cut-off (or for umut101, living with a hole that departed from the 5dB plus or minus band of 40-60)"

Bad of you to make DIYaudio a place for "scoring points" instead of helping others.

DonVK - I posted a chart comparing my MacBook mic with my calibrated mic. Pretty reasonable to use the laptop mic over most of the range. For the OP's problem, the measurements are relative from one location or test run to another; so it just doesn't matter what the absolute accuracy might be.

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Old 8th November 2017, 09:01 AM   #26
chris661 is offline chris661  United Kingdom
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Originally Posted by bentoronto View Post
Data! Great. You're now on the high road to better sound. Fair to say that for many recordings, you'd hardly notice the loss, even if folks on this forum would be aghast at the below-50 hole.
Quote:
Originally Posted by bentoronto View Post
Deceitful to quote me out of context. In that same post said "No, I wasn't advocating a 70 Hz cut-off (or for umut101, living with a hole that departed from the 5dB plus or minus band of 40-60)"

Bad of you to make DIYaudio a place for "scoring points" instead of helping others.

B.
I can see why JAG got frustrated.
No problem, though.

The whole reason for this thread is that the OP did notice the big hole in the frequency response. Read your first quote again.
Also note that the hole in the response starts at 70Hz and is back up again at 35Hz. In between, it drops to 40dB below the rest of the range.

You just seem to be contradicting yourself. I'm not out to score points. I'm here to make sure we're not spreading misinformation. When I see it, I'll call it out, and this is one of those cases.

Chris
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Old 8th November 2017, 05:00 PM   #27
DonVK is offline DonVK  Canada
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@umut, I went back to post #1 and looked at the photo. Are your front speakers some kind of TL or MTL to extend the bass?

With a FR hole as large as you have, it might be from out of phase overlap between the front and the sub. This would cause cancelling over a wide range, depending on how they overlapped, and their relative phases, and how you do the cross over between them.

Also when you measure again, you should use at least 1/12 octave smoothing. The room nulls will usually be sharp dips, not a wide hole unless you have several close together.

Last edited by DonVK; 8th November 2017 at 05:00 PM. Reason: typo
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Old 8th November 2017, 07:25 PM   #28
umut1001 is offline umut1001  Europe
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Hi.I am not working the QWTL 5 inch FR speakers which under the 4 inch sealed FRs.I liked and prefer 4 inch ones on top of them(they are working as sealed in about 5 liters of birch plywood boxes) and sounding better to me.They are working together with big 100 liters of cube subwoofer on the left.Sound is very impressive and nice to listen to me but some bass frequencies decrease a lot when i sit down.Yes i will also make some more tests with 1/12 octave smoothing too.I fighted with wife when making measurement tests yesterday,the subwoofer amp was at max volume and i did not know it(500w class d).An earthquake happened and all the house shaked a bit with test.However today is my birthday and we are in a peace now with wife maybe another tests will be again in a few days
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Old 8th November 2017, 07:37 PM   #29
scottjoplin is offline scottjoplin  Wales
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Another alternative would be to have the sub very close to you.......under the sofa...not an uncommon position, it should deal with all room modes
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Old 8th November 2017, 09:27 PM   #30
DonVK is offline DonVK  Canada
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@umut, you can also do your tests at moderate levels (70-80db) , no need to stress the house and occupants.
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