Finally Have BFD First Measurement

[11B2P]

Hello,

Sorry about the thread title. It should read Finally have BFD and made my first measurement.

Ok I made a measurement of my PB12-Plus and have attached the graph.

Where to start? What do you guys think? Any advice?

Does the dip at 45 look too bad for the BDF to take care of?

Thanks for your help.

-Bill

[brucek]

Does the dip at 45 look too bad for the BDF to take care of?

You reduce the humps first.

Are your mains on? You should measure the subwoofer by itself.

What's your crossover set at?

brucek

[11B2P]

Only the sub is on, mains are off.

My Onkyo TX-DS787 pre/pro does not tell me where my crossover is set at.

I do have all speakers set to small.

Work on the humps first, right.

Thanks brucek!

[11B2P]

I checked my owners manual and found that if speakers are set to small then frequencies lower than 80Hz are output to the sub.

So 80Hz is the crossover setting.

-Bill

[brucek]

So you'll be trying for something like the pic below as a target.

Once achieved, then you can set the overall level of the sub to suit against the level of your mains.

You can also throw a small amount of gain at the dip left over to see if it responds at all to gain. Sometimes it does and sometimes not. If not, don't waste your time (and headroom) - leave it.

Never add more than 5dB gain......




brucek

[11B2P]

Thanks brucek!

I will report back and let you know how things are going.

I appreciate the help.

-Bill M.

[11B2P]

Ok, I made some corrections with the BFD.

The dip at 45 Hz is here to stay. At least until I can get room treatments.

I am having a of a time with the hump at 63Hz.

No matter how much I cut the hump at 63Hz stays. In fact it went up a little.

Here are my filter settings so far:

Freq Setting+Fine BW Gain
20 20+0 12 -5
25 25+0 10 -6
32 32+0 7 -7
40 40-8 8 -5
50 50-8 10 +5 (all the higher I am planning on going with the gain)
63 63-2 12 -20

Any ideas? Have I got the bandwidth messed up? Should I be using fewer filters?

Thanks for the help.

-Bill

[brucek]

No matter how much I cut the hump at 63Hz stays. In fact it went up a little

Looks good up to 50hz. I can't imagine why the 63hz filter won't cut. The 50Hz filter will have a small influence on it from its 10/60 BW setting, but the 63hz filter of -20dB is huge. I can only think you don't actually have it set to PA or perhaps (and lots have made this mistake) you've set it to .63 rather than 63 . This would mean 630Hz rtaher than 63hz...........

brucek

[11B2P]

Hi brucek,

All good points.

I will recheck my filter settings. It is very possible I made some mistake.

I have another question, is it possible to skip a filter and set the next one? I am wondering if I can save a filter for later use or do I have to use them in sequence.

i.e. I set filter 4, skip filter 5, set filter 6.

Thanks again.

-Bill

[brucek]

I am wondering if I can save a filter for later use or do I have to use them in sequence.

Any order or out of order is fine. Simply turn an unwanted filter to OF to eliminate it.

[Wayne A. Pflughaupt]

The dip at 45 Hz is here to stay. At least until I can get room treatments.

I don’t see any filter set to address 45 hz in the list you gave. Or maybe you did not include it because it wasn't working? It would be unusual for a depression that wide not to be “equalizable” (is that a word? ). For example, this is brucek’s “before” graph, and he told us the notch at 28 Hz would not respond to EQ. Notice how narrow it is:

I am having a of a time with the hump at 63Hz. No matter how much I cut the hump at 63Hz stays. In fact it went up a little.

That’s typically caused by the mains overwhelming the sub. I know you said you turned them off, but above 63 Hz this last graph looks just like the first one you posted, that had them running.

Regards,
Wayne

[11B2P]

brucek and Wayne!

Wow guys thank you for the help!

I really appreciate two heavy hitters such as yourselves giving me a hand.

brucek you called it .63 was selected for the frequency. I guess that is what I get for trying to set filters at midnight after a long day at work.

Wayne I never had the mains running for any of my measurements; just the PB12-Plus. I turn off my amp before making any measurements on the sub. I am running this in a dedicated room 13 feet wide by 17 feet long with 8 foot ceilings. Maybe I have the sub up too loud for my room size? I started my 16Hz measurement right at 75db on the RS SPL meter.

I also noticed quite the difference in db (about 8 lower on average) when I measured a 16Hz tune on the Plus. I decided to not use 16Hz tune because I would have to boost a lot from 16Hz to 31.5Hz. (I always thought too much gain was bad for the amp.)

I tried addressing the dip at 45Hz. (I am calling it 45 Hz but correcting at 46).

My filter settings for the dip are: 50 50-8 10 +5 (all the higher I am planning on going with the gain)

Am I figuring this wrong? I am such a rookie that it is always my first suspicion.

Thank you again guys, I truly appreciate your valuable assistance.

-Bill M.

[brucek]

Am I figuring this wrong?

No, everything seems good. As you say, +5dB gain is indeed the limit. If there's a dip, so be it..

Once you finish you should post a new graph....

So have you considered using Room EQ Wizard software?

brucek

[Wayne A. Pflughaupt]

I tried addressing the dip at 45Hz. (I am calling it 45 Hz but correcting at 46). My filter settings for the dip are: 50 50-8 10 +5 (all the higher I am planning on going with the gain)

I haven’t actually used a BFD yet, but if I’m not mistaken the “50 – 8” adjustment should mean the filter is set at 42 Hz, right?

Nevertheless, you boosted 5 dB and it’s showing on the graph, so it looks like it is responding. I’d go ahead and boost it some more – at the right frequency - and see what happens. The PB12 has a built-in limiter, so you can’t overdrive it.

What gain setting have you been running the sub at? (i.e., 9:00, 12:00 etc.)

I also noticed quite the difference in db (about 8 lower on average) when I measured a 16Hz tune on the Plus. I decided to not use 16Hz tune because I would have to boost a lot from 16Hz to 31.5Hz. (I always thought too much gain was bad for the amp.)

So you’re saying that in 16 Hz tune everything below 31.5 Hz “sags?”

Again, the amp has a limiter, so I’d give it a shot. You can always dial it back if it isn’t working well.

As far as the 63 Hz situation, I’ve never seen it be anything but the mains being on, so my next guess is that particular filter isn’t actually activated. Check and see. There’s no way I can think of why a peak should not respond to a cut.

Regards,
Wayne

[Sonnie]

50 - 8 = 46 Wierd math if you ask me. Actually though, it is 50hz - 8/60 of an octave = 46hz.




I agree on the peak at 63hz... something's not right about that. You are measuring a tone at 63hz... assuming you are using 1/6 octave sinewaves, but you have adjusted 62hz (63 - 2)... not that it would make that big of a difference since you are using a 12/60 bandwidth and a 20db cut. That ought to suck it off the map...

[brucek]

He already found the fault a couple posts up when he admitted:

.63 was selected for the frequency. I guess that is what I get for trying to set filters at midnight after a long day at work.

He had 630 Hz selected instead of 63 hz......we've all made that mistake..

brucek

[11B2P]

Ok here are my second corrections. (See PB12Plus20Hz2ndcorrection.gif)

I did the best I could with the dip at 45Hz.

I used 2 filters one at 45Hz (40+10/60) BW4/60 Pos 5 gain
and the other at 48Hz (50-4/60) BW4/60 Pos 5 gain

If I cut the small hump at 56 Hz will I be chasing my tail or will it really make a difference?

Sorry about screwing up the .63 filter, guys.

Using Room EQ would require me to go buy more gear. (WAF problem there.)
I have considered it but probably will not use it.

-Bill

PS:
Wayne, I also attached the first measurement run at 16Hz tune. (Please see PB12Plus16HzTune.gif) Current gain setting on the sub is 10:00.

[brucek]

Yep, really good job Bill. You may have to increase the overall level of your subwoofer amp a bit, but it will handle it.

The next thing you're suppose to do now of course is a measurement with your mains turned on and plot the same response to check for crossover interaction. Sometimes around the crossover you'll get a hump that is the interaction at that frequency between the sub and mains. You can filter it down a bit if possible.

All this is so easy with REW of course. We know you have a computer, so there are only a few cables to buy to get it going. Of course, you have to drag your computer out to the equipment, and sometimes that doesn't work out so well with the rest of the family.

brucek

[Wayne A. Pflughaupt]

brucek wrote:

He already found the fault a couple posts up when he admitted:

.63 was selected for the frequency. I guess that is what I get for trying to set filters at midnight after a long day at work.

He had 630 Hz selected instead of 63 hz......we've all made that mistake..

Maybe it would behoove some of us to actually get and use a BFD so we would have known what he was talking about, instead of making fools of ourselves telling him to make sure his filter is on...

Actually, I just acquired one from Sonnie, so I’m going to take my own advice and read up on that BFD Guide.

11B2P wrote:

PS:
Wayne, I also attached the first measurement run at 16Hz tune. (Please see PB12Plus16HzTune.gif)

Wow, that’s quite a sag! I guess it goes with the old subwoofer rule that increased extension usually comes at the expense of output.

Current gain setting on the sub is 10:00.

Is that your after EQ setting? I guess what I’m trying to figure out is what you were running it at before, vs. what you’re running it at after EQ.

Regards,
Wayne

[11B2P]

Hi Wayne,

The sub amp gain setting is before BFD settings. I am planning on upping the gain to rebalance with my other speakers.

But tonite, I watch a movie!

Tomorrow I will re-eq with the mains running like brucek suggests. (I would have never thought of that.)

Thanks again guys!

I would not have been able to do this without the BDF guide and your kind assistance.

-Bill M.