Klipsch SUB-12 Subwoofer (1 Viewer)

[Robert_J]

You need to start at 40hz and pull down that peak. Can you attach the original Excel file to a post? I'll tweak the simulated EQ and see what I can come up with.

 

[BraveHeart123]

Here are the SPL values in the attached sheet. Pls see if u can achieve the house curve along with the flat response.[ATTACHMENT=177]FR_withoutBFD.xls (1,613k. xls file)[/ATTACHMENT]

 

[Robert_J]

[ATTACHMENT=179]FR_withoutBFD.xls (1,602k. xls file)[/ATTACHMENT]
Plus or minus 3db down to 28hz. Your sub's subsonic filter is the limiting factor in the low frequency response.
For some reason, filter 9 on the macro wouldn't update. I skipped it.

 

[BraveHeart123]

I tried to make it as flat as possible down to 30 hz. Check the image below;

In the chart above, 3rd and 4th filters have 8db and -8db gain setting, respectively. Does it mean the wider bandwidths of both frequencies (31 hz and 34.8 hz) affect eachother and the net effect on the amplifier won't be much??? I just need to know how much 8 db gain at 31 Hz would tax the amplifier considering the bandwidth and -8db gain at 34.8 hz.
That's another setting for house curve;

......Your sub's subsonic filter is the limiting factor in the low frequency response.

My sub goes down to 24 hz. Do u mean that the sub-sonic filter is faulty or mal-performing??

 

[Robert_J]

Does it mean the wider bandwidths of both frequencies (31 hz and 34.8 hz) affect eachother and the net effect on the amplifier won't be much???

Yes, they affect each other but there is still a strain being placed on the amp by boosting the lows 6db. You have to double the power for a 3db gain. The Klispch sub doesn't have much headroom to play with. If you listen low, it's not a big deal. Crank it and you risk burning up the amp and/or destroying the driver.
I'm thinking that valley at 66hz is a room induced null. Have you tried to measure the room in a different location to see if it changes? If it is room induced, you can boost it by 100db with minimal impact to the valley. The room is sucking the life out of that spot.
I like your flat response much better then the house curve.

 

[BraveHeart123]

I think I found the problem. When I ran YPAO on RX-V3900, I forgot to reset the PEQ settings on avr for the sub after it. I normally check the PEQ option on avr during auto calibration but only keep the settings for the mains/center/surround and reset any parametric equalization for the sub. I think that 66 hz dip is added by the avr for which I need to boost so much.
To what levels do u calilbrate your mains/center/surrounds as opposed to the sub? I am calibrating the mains at 70 db and sub around 73db before applying BFD filters. I have avia also but dont use it.
UPDATE: I just checked my avr was using built-in PEQ for sub, which had a one actave wide (-1.5 db) filter centered at arnd 62 hz. Though I disabled the filter, do u think this could possibly be the culprit??

 

[Robert_J]

I calibrate my my system using MCACC only after I get a flat response on my sub. Otherwise, it is a waste of time. And yes, my sub runs 3db hotter than the MCACC automatically sets it to.
Yes, that could be the culprit.

 

[BraveHeart123]

I've read on other threads that most of the people don't use more than 7 filters at the max, whereas I end up exhausting all the 12 filters. Although I am also normally done with 6-7 filters, but I use all of them in order to make the response as smooth as possible like a line.
I need to know is it really necessary for the response to be like a smooth straight line just like the PEQ charts (Flat and House Curve) I posted earlier?
Also, even with such smooth looking settings when I measure the response again after applying BFD filters, the response is never close to what PEQ spreadsheet predicts. Shall I keep it simple by just removing specific peaks and valleys and forget about making the response smooth and use up all the filters???
Coz I think wats happening is too many filters close together either cause further dips or boost peaks coz of overlapping bandwidths and +/- gains at adjecent frequencies.

 

[Robert_J]

when I measure the response again after applying BFD filters, the response is never close to what PEQ spreadsheet predicts

That's odd because when I measured after setting up my BFD, it was dead on. Make sure you use a fresh spreadsheet with no filters applied.
I've never noticed that most people only use 6 or 7 filters. That's all I need but that's all I needed to get a simulated and real-world response that I wanted.

 

[BraveHeart123]

Make sure you use a fresh spreadsheet with no filters applied.

Obviously I use fresh sheet coz if i dont; it will be like applying calibration filters twice for each frequency. Anyway I applied my logic, removed all the dips and spikes in the raw SPL but did not make them smooth. And the result is non less than ballistic. Even the low end extension is pronounced and smooth. See the before and after calibration graphs;
Before Calibration

After Calibration

 

[Robert_J]

And the result is non less than ballistic. Even the low end extension is pronounced and smooth.

That's great. I know it takes time especially learning something new via a forum like this. I'm glad things worked out. Since using the BFD to flatten my sub's in-room response, I have been a proponent of using a sub EQ.

 

[BraveHeart123]

Thanx loads Robert for your help. It's a great forum for learning especially for people like me sitting thousands of miles away. Coming from car audio background, I was totally in oblivion about how an HT should sound. They both are poles apart. Car audio is nowhere close to what a properly tuned HT has to offer.
Anyway thanx again n I hope I learn mre stuff from this forum and people like u.

 

[Mike Frezon]

Excellent thread, gentlemen. It has been fun to watch this discussion develop. Although I don't pretend to know a small fraction of what was said or what it means.

I think I need to go to Robert_J boot camp!

Faisal: I'm glad you got the help you needed here. You've already gotten a taste of the great membership we've got here (through your discussion with Robert_J). I hope you'll hang around and kick the tires on the place and see what else the HTF has to offer.

I can tell you right now that this observation of yours:

Coming from car audio background, I was totally in oblivion about how an HT should sound. They both are poles apart. Car audio is nowhere close to what a properly tuned HT has to offer.

is something I hope a lot of our new members will read. We get a lot of car audio people who gravitate here and not understand the distinctions between car audio and HT. Thanks!

 

[BraveHeart123]

Hi Robert ... Problem...I think my sub has developed some problem in it. Yesterday I eq'd it using BFD as below;

As u can see the SPL is between 85 db to 91 db from 25 to 100 hz. But last night I popped in Avia to level the sub, it showed 68 db at my reference volume, which is way too attenuated. It should've read 85+. Then I bypassed BFD, connected the sub directly with avr, and checked the sub level with internal test tone for sub; again RS SPL meter read around 70. I swapped different cables but to no avail.
I am also using Seagate FreeAgent Theater+1080P HD Media Player for playing mkv files. When I played specific test tones for sub calibration from it, the SPL came back to what it was plotted in the chart above.
I played different movies in DVD player, they all have attenuated LFE response. Now these are all my test movies. What could be the problem here??? Why is internal test tone on AVR for the sub reading so low?? It wasn't so a couple of days ago .... even movies from DVD player had no problem. I hope my AVR hasn't developed problem in sub pre out.
Worried more than confused..... Need help.

 

[Robert_J]

Do you have BFD set to 4v (I think) input level? Have you upped the output of the LFE at the receiver? Have you upped the output of the BFD?
Your test tones were recorded at 0db and Dolby Digital/DTS is -10db so that accounts for it being 10db below your Avia settings. Just boost it up a little to make even with the rest of the speakers. Flattening the response is not intended to set the appropriate level.

 

[Robert_J]

I think I need to go to Robert_J boot camp! biggrin.gif

You have been here almost as long as me and definitely been more active. If you search the archives, this is covered many times in the old DIY section. The BFD is still highly popular but things are progressing to a box called the "mini-DSP". It is a parametric EQ along with a subsonic filter and can even do a shelf EQ if needed. I'm waiting on the early adopters to get the bugs out.

We get a lot of car audio people who gravitate here and not understand the distinctions between car audio and HT.

In the last year I've gotten back into car audio. I've been helping a local kid with his car projects and he helped me be one of the first 5 people in the world replace a head unit in a Lexus ES-350. He's big into competitions and says that my car sounds as good as the defending USACI sound quality winner, just not as loud. I used the same principals going into that install. I may even plot my in-car sub response.

 

[BraveHeart123]

The buttions on BFD rear panel are set to -10 dBV position .
Never lowered LFE level on AVR. It is set at 0 dB.

Have you upped the output of the BFD?

Did u mean keeping the button on BFD back panel to +4 dBV position?? I dont know how to rasie the ouput on BFD apart from increasing the gain on filters to increase output.

Your test tones were recorded at 0db and Dolby Digital/DTS is -10db so that accounts for it being 10db below your Avia settings.

Which test tones are we talking about? Is it the ones I created using NCH software for subwoofer calibration OR the built-in test tones on the receiver OR the ones on Avia??
What is happening is when I level match my mains/center/surround and subwoofer with AVR built-in test tones at my reference main volume (-10 dB), I set them to 70 dB and 73 dB respectively.
But when I check on Avia, it is 80 dB and 78 dB for speakers and sub respectively. which tones to use??? AVIA or AVR tones?? Now I'm confused.

 

[Robert_J]

I checked and my BFD is set for +4 as well.
I could have sworn there was an overall gain control on the BFD but I was wrong. It's been years since I set it up but I need to get back into the game since I am recommending it as well as switching out my subs pretty soon.
The test tones created by NCH. You don't care what SPL those are. I chose 85 db on my meter since that masked outside noise and gave me a wide margin to work with.

which tones to use??? AVIA or AVR tones?? Now I'm confused.

Yes, it can get confusing. Other than the difference in overall volume, are the different speakers level matched? After doing the receiver setup using YPAO, check it with Avia. Are the levels correct? It sounds like the sub is a little quiet and that happens when I run MCACC. I just boost it 3db at the receiver. Other than that, the -10db or whatever is showing on the receiver makes no difference. It's an arbitrary number. If you can reset it to match Avia, then it should be reference level. I can't reset mine. In fact, since my receiver is behind me, I never know what the volume is displaying.

 

[BraveHeart123]

OK lemme rephrase the problem......The overall smooth output from sub is gone and it is crude now. The subtleness I talked about before i.e. the low end persistent growl at low volumes is no more, that room filling subtle low end bass is missing now.
It was room filling low end subtle growl that I could get at -10 dBV button position on BFD rear panel.
It was very much there when I thanked u thinking that was it and was done with sub calibration, but the following morning it was all gone.
One thing I must mention here that I was using Chord Crimson Plus (8 meter) sub cable from BFD out to sub LFE in. This cable was lying on the floor n was unpleasing to eyes. So I tucked it in wall ducts, bending along the door frame and found it to be 3 feet short to the sub. So I added a cheap female-to-female RCA adapter to join it with another sub cable from a different company.
Do you think this could be the problem for this whole mess up??? Also, -10 dbV OR +4 dBV......which one to use on BFD???

 

[Robert_J]

Yes, it could be the cable. If you broke the shielding and created a short there are all kinds of problems. I would say that sub cables are cheap but I don't know about over there. Even if you can get RG-6 or RG-59 coaxial cable, that will work. In fact, it works great as a sub cable.
Does YPAO add EQ to the sub or just set the level? If it adds EQ, can you manually remove it and just leave the level setting? Or use Avia to set the sub level.