Axiom Home Page Forums General Discussion Home Theater BFD & 600s All Set Up

Much thanks goes to Doug, Peter,Adam, and Lee for spending over 5 hours here today on calibrating and adjusting the BFD and the twin 600s. There is a VERY noticeable differance with having the two subs, and also with the BFD in the system., as the graph below shows. Blue is without the BFD and pink is with the BFD added, in my opinion, the BFD was worth the extra investement and time. Had it not been for above people, I would have been here for weeks getting it set up on my own.

WOW! That is a pretty nice final graph.

Wow... that's mighty nice for "in room" response.

Did you tell them where MarkSJohnson lived ?

Yeah man that looks really good.I wish I could hear those bad boys .

Only wished Mark was close enoguh to get the kind of help I did, I'm very lucky to have such kind offers of assistance.

Thanks again for having us over, Dennis, it was a lot of fun!

I've never heard a system sound so effortless at such high volumes - I played the 2nd movement of Beethoven's 7th symphony after we'd done a basic speaker and sub level calibration, and was amazed. There's simply no dynamic restraints! For those of you familiar with the piece, it starts off fairly quiet and builds to a nice fortissimo, and during the quiet passages it was probably around 85db or so. I'm used to hearing a little strain from anything I turn up that loud, but the fortissimos were as effortless as the pianissimos. Impressive! Although, it becomes very apparent (or should I say, painful) which cds were mastered hot at those levels. Stick on a bright cd and you're left wincing at every cymbal crash or "s" sound from the singer. Stick on a good cd, and man, what a treat!

After we'd spent a good couple hours measuring room response and calibrating the BFD, the system was really something else. The subs took the most time to calibrate and really get a smooth response, but once that was done, the sound was just awesome. Smooth, clean, in your face and right in your chest. From Darla (Finding Nemo) to depth charges (U-571) to rockets (Incredibles) to music from Beethoven to A Perfect Circle and everything in between - this system is MIGHTY impressive. I don't think I could listen at the levels Dennis usually listens to for long, but I could understand the temptation to when it sounds so effortless.

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...I played the 2nd movement of Beethoven's 7th symphony...

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Hey! That's on my mix cd that Tharkun will likely receive tomorrow!

Yup - when I looked at the track listing on your mix, I noticed it and smiled. I think that's my favorite movement out of all of Beethoven's symphonies. Maybe even all his work, period.

The kiddo is down for the night and my wife has gone to bed (and the dishes are even washed!), so I can now concentrate on an official report of the latest visit to Haxiom Theater.

The main event today was calibrating the subs and tweaking their in-room response with the Behringer Feedback Destroyer. Doug (dougmcbride), having the most experience calibrating subs, manned the command post and directed the calibration efforts. My brother Adam (AdamP88) and I manned the Denon 2900 and Parasound C2 remotes. I also did the button-pushing on the BFD. Lee (koiman) lent his ears and brain to assist in calibration decisions. Lee brought his wife (whom he referred to as "his navigator"), who valiantly tolerated the high levels of geekery oozing from the rest of us who were engrossed in the calibration process. When they arrived, she saw the SPL meter on the tripod and said "I know what THAT thing is! That means there's going to be loud noises."

After we took the initial readings (the blue line in the graph above), Doug broke out an online tutorial for configuring the BFD as a bass response "smoother-outer". All of us were expecting it to be a bitch and a half to set it up, but it actually went quite smoothly. It helped that the tutorial was pretty good and that I'm really great with buttons.

The great thing about the BFD is that it allows you to precisely specify which frequency you want to correct, and the bandwidth to the left and right of that frequency point you want to be affected. We ended up using 6 of the available 12 frequency filters. The results speak for themselves.

Prior to calibrating, we watched the U-571 depth charge scene. Doug noted that it sounded a bit anemic. Post-calibration, that same scene produced the chest reverberating sensation Doug was looking for. Most impressive!

I would highly recommend a BFD to anyone as a cost-effective (only $108) way of dialing in sub room response. You could easily spend more than that amount on room treatment and bass traps and not come close to the results we achieved withthe BFD.

Of course, it always helps to start with great equipment.

Peter, excellent results with the 600s and BFD. Unless I've lost it in some post I've missed(been doing tax returns; finished!!),there hasn't been any discussion of how the 600s were located for the blue line readings or whether alternate locations were tested before the BFD did its thing. One of the interesting papers on the Harman site tested a bunch of alternate locations for single or multiple subs.

Ah, what an oversight! The subs are co-located along the wall to the right of the main seat in a way that does not take advantage of corner loading. We actually did not play with placement at all. Adding that variable to tha mix would have been too much for one day.

I don't mean to speak for Dennis, but I get the impression that he decided, for whatever reasons, that where they are is where he wants them to be. Today's task was to get them sounding as good as possible in that position. Going by the final curve, it appears they succeeded.

I'd say you're right. After all, he did go to the trouble of building them a nice oaken home.

Lookin good Dennis. Time to relax and enjoy now that you're done messin with the system for a while.

Having to deal with the floor plan I now have, along with the addition of the raised platform and theater seating, the location of two 600s was very limited. Prior to ordering the second 600, I had tried placing the 600 in two other locations, and found no significant increase in bass response. Once the decision was made for a second 600, that rather determined the placement of the twins and I gambled on using the BFD to solve any room issues.

The system is in my opinion about the best I can make it with the existing fllor plan and use of the areas. I still have a few issues to resolve like cabling for the subs need to be concealed in the walls. The cables/wires for the equipment rack needs to be organized and secured. As all seen yesterday, replacement of the component video cable for the Denon 2900 is going to be ordered today. The Halo C2 has BNC connections, and currently the BNC to RCA adapters are not working, becasue of the amount of base, they vibrate just enough to break up the video. So replacing them with RAC to BNC component cables.

Once again, I thank all that have vistied and helped me with the tweaking and set up, Axiom for great support, and this forum, the combined knowledge of this forum is the best one could find.

With your wisdom as usual Jack, you have it right. The placement of the twins really only had one location, unless I wanted to start moving walls. lol

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With your wisdom as usual Jack, you have it right. The placement of the twins really only had one location, unless I wanted to start moving walls. lol

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With your skills, it wouldn't surprise me one bit if you did.

Dennis, Doug, Peter, & Adam,
At last a face behind the names, what a great experience to be involved with such a great group of guys. I sure learned a lot just watching and listening. Even thou I have a BFD and had set it up over 2 years ago it still was a great rush. After all was said and done Dennis you have a fantastic system, and I am sure you are the envy of many. Also Rita wanted to say thank you for the interesting afternoon and the ability to hear after we left. Oh by the way Dennis thanks for the battery jump, I was so intrested and excited to get to Dennis house that I left my Head lights on in my car for 5 Hrs. and when i got ready to leave you guessed it
Thanks Again,
Lee

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unless I wanted to start moving walls. lol

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Well Dennis, moving walls around your place shouldn't be too much of an issue. Seems like a little turn of the wrist ought to move just about anything you damn well feel like moving.



Have the neighbors complained yet?

Not moving walls, I needed to remove 22' of the origanl 35' back wall of the house for access to the solarium and spa, that was enough. lol

Nah, no problems with neighbors, all the sound goes out the back and front, only issue is when neighbors are at the door, they need to wait for CD tracks to change to get me to answer the door. Which is good, as usually they have some project they want help with. Like will you build me a CD cabinet like one of yours, and they have a budget of $50.

Well that's mighty nice of you Dennis, er, uh...I mean NEIGHBOR!

If I ever make a trip out your way, you'll definately be getting a visit from me. Providing you do not mind of course. That is one tremendous system you have there Dennis!

As things were being set up yesterday, Doug mentioned that once things were dialed in, I should not move or change things, so I figured that means I don't have to finish the marble flloors, the fireplace, cabinets, and I would need to have the same body mass well using the system. So told all that were here I would call in advance of playing music or movies so they all could arrive here in time.

Sorry for chiming in late - it's taken me all morning and half the afternoon to catch up missing one day of work (Dennis - you were right, per usual, on that topic).

Yesterday was really a lot of fun and I believe we verified that having multiple enthusiasts together for an exercise like this is much more productive - as well as just a lot of fun being around folks with the same passion and who can speak the same lingo. Almost like a HT barn-raising in a way.

Dennis, thanks for being such a gracious host since we took over your living room for most of the day, and thanks Peter, Adam and Lee for the additional brain power, subjective opinions, and extra fingers to run all the equipment. We had a real assembly line going there for a few hours. I think all in all, we captured five or six calibration runs as we were tweaking Dennis's room - when doing my own by myself I can usually only get in about two in the same amount of time.

I'd also like to note what a great spouse Lee has. Rita sat through this whole ordeal with aplomb, tolerating the room full of male HT geeks only like most patient women can. I told my wife about it and she just smiled and said I'd never get her into one of these sessions without running out of the room screaming after an hour or less.

We were all happy with the result we got after the five hours or so we spent on it. I wanted to keep tweaking a bit more, but the beasts wanted to get to the meat - demoing Dennis's system in its calibrated state. Thanks to all for the kind comments - it is a pretty good looking room now, but we still had some issues at the crossover point from the M80's to the EP600s which can be seen at the tail end of the graph. We played a little bit with phase around that point, and a little bit with the BFD, but at this point most were getting a little glassy-eyed. Gives us something to work on for a future calibration session. Personally I think working on the phase issue would allow us to flatten that part of the curve a little bit, but as everyone commented, the system sounds excellent, and from my perspective, much better than when we started.

From a BFD perspective (I had never even seen one except in pictures before arriving at Dennis's house), it really turned out to be a simple experience after we played with it for one or two interations. I had read many, many horror stories about folks having trouble using the unit, but it always boiled down to them making it more complex than it needed to be, using too many filters, etc. We all kept each other honest in making this simple, and the BFD is a very precise instrument, letting us nip and tuck in a very methodical way. I was personally impressed by how little the filters interacted with each other, which is what leads to nightmares when trying to EQ.

Cheers,

Doug

Tharkun,

Excellent work by everyone. I'm impressed, and if I can ever get away from this laptop and Axiom demands (ha, ha), I'll take you up on your kind invitation and head out to the West coast to hear your installation.

The pink curve with BFD certainly looks great, and the comments by the experienced listeners present seem to back it up.

Regards,

Just an update, its been four days of listening to the system after the BFD set up. After four months of working on getting the system together, I'm happy to say its finished, the addition of the second 600 and BFD has provided all of the base I was seeking. The twin 600s was worth the expense and time, there is more than just a subtle increase.

So until someone with a more critical ear than myself can offer an improvemnt in the sound quality, I quit for now, other than Doug still wanting to return and tweak some with the BFD to improve the drop off, I'm going back to other house projects.

I did order a Sony ES DVP-NC555ES for a back up unit, as it seems the Denon 2900 is in need of going in for service, its refusing to read some DVDs, and I don't care to have the system down for weeks. Will use the Sony for every day playing of CDs and will extend playing time since its a five disk unit.

Once again, thanks for all of the help and support over the last several months, it has made this system a top end one, and way more than what I had in the origal thoughts..

Just updated the web page with the only picture taken well doing the BFD set up. From the left its Peter, Doug, and Adam.

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Peter, Doug, and Adam

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Dumb, Dumber, and.......

well, you get the picture..

thank you very much, i will be here all week!!

bigjohn

You call a shot where it looks like I'm picking my nose coming out well??

I think he meant to type the word "while" not "well".



WhatFurrer

I wasn't going to say anything about the picture ...

Good thing you had kids before sitting that close to the two EP600's.

Hi everyone!

Been lurking for a long time.....great forum.

I have a question for all you BFD tuners here. First let me give you some corrected SPL numbers:

Rat Shack meter, C-weighted, slow response:

18hz @ 68db
20hz @ 71.5db
23hz @ 80.5db
26hz @ 87db
29hz @ 95db
32hz @ 98db
36hz @ 102.5db
39hz @ 102.5db
42hz @ 100db
45hz @ 98db
51hz @ 97.5db
57hz @ 102.5db
63hz @ 98db
72hz @ 95.5db
78hz @ 92.5db
84hz @ 93.5db
90hz @ 98.5db
102hz @ 87db
114hz @ 84.5db
126hz @ 90.5
132hz @ 89.5db
138hz @ 89.5db

Sub is a psb subsonic 3, 12" driver w/180w amp.

X-over on sub is dialed to it's 150hz max.

Receiver's X-over is at 80hz(12db/octave high pass, 24db/octave low pass).

I currently have a BFD running bypassed, and am wondering if I should even use it, and if so, what should I focus on?

Thanks for any opinions!

No, you shouldn't use it. I'll give you an address you can ship it to... I'll just take care of that for you.

Good one Ken, you beat me and a few others to it I think.

Why I oughtta.....!

Whatch it, or I'll get Ajax on you!!

I had some time to kill, so here's a chart of your response:



Here's the Excel spreadsheet file, as well.

May I assume that your target reference db was 95? If so, then I'd start your tweaking with 3 filter points:

One at 40Hz, with a bandwidth of 1/4 octave, and a cut of 6dB
One at 57Hz, with a bandwidth of 1/8 cotave, and a cut of 8dB
One at 80dB, with a bandwidth of 1/8 octave, and a boost of 3dB

These are very rough estimates, but they should result in a flatter response.

Wow! Looks like the spreadsheet I did! Thanks pmbuko, I am going to try those filters out. Actually, I set the meter to read 74db at 23hz(uncorrected), but the 95db level will work. The sub really drops below 30hz like a rock.....surprised me.

Lovely graph.
Time to kill?
You know i have these groceries that have been on my list for about a week along with a garden to clean out...

What can I say, I'm over 1000 miles away from my chores...

**think Proclaimers**

NOW I WOULD WALK 500 MILES, AND I WOULD WALK 500 MORE.
JUST TO BE THE MAN WHO WALKED 1000 MILES, TO FALL DOWN AT YOUR DOOR!



hey, i got plenty of stuff for you to do, and i am only about 240 miles away...

bigjohn

I like NOFX's lyrical response to the Proclaimers in "Whatever Didi Wants":

I wouldn't walk 500 miles when I could fly coach but almost anything
I wouldn't swim across the Nile cause I could get amoebic dysentery

'Cause if there's anything you want
I'll probably get it
you tell me what you need
I'll try not to forget it
you need someone to blame
I'll say I said it
Whatever Didi wants
She's gonna get it

I wouldn't climb the highest mountain could get a blister, but almost anything
I wouldn't throw coins in a fountain I might be needing to make a phone call

It doesn't seem like you're a million miles away, no... but maybe one or two
That doesn't mean, I never loved you. Me love you long time... when you're on top of me

Now that's my idea of a punk love song.

Bren R.

Okay...

I set up the three filters as suggested pmbuku!

A quick listen showed promise, but I won't be able to take measurements for a few days.

I'll post the results when I do.

Ed - In addition to what Peter suggested, Add a boost of 6 dB at 28 Hz, bandwidth 1/3rd octave ... just be careful not to overdrive your sub....

I had the identical sub in the 90's ... and with EQ, you can get to about 25 Hz with that EQ ... and it has decent protecion circuitry...

Thanks Craig! I'll add that and let you know what happens.

What is your opinion of my sub and how it compares to these present day subs, such as the axioms, Hsu's, Onix, etc.?

Ed- It would be about comparable to a Hsu STF-2 ... and is a pretty decent unit.

Okay Craig and Peter, here's some CORRECTED numbers with the filters you guys suggested.....

18HZ @ 63DB
20Hz @ 67.5db
23Hz @ 78.5db
26Hz @ 87db
29Hz @ 92db
32Hz @ 93db
36Hz @ 92.5db
39hz @ 91.5db
42hz @ 90db
45hz @ 89.5db
51hz @ 88.8db
57hz @ 88.5db
63hz @ 88.5db
72hz @ 91.5db
78hz @ 92.5db
84hz @ 76.5db
90hz @ 89db
102hz @ 87db
114hz @ 76.5db
126hz @ 79.5db
160hz @ 80db

Filters are as you guys posted:

40hz, 1/4 octave, -6db
57hz, 1/8 octave, -8db
80hz, 1/8 octave, +3db
28hz, 1/3 octave, +6db
Looks like a spike in the 70hz-80hz range, then a big dip after 80hz.

This is running all speakers. I did raise the sub level a few decibals after filtering.

Overall pretty good, I'd say!

Alright...all you guys plotting your subwoofer response has the geek in me really itching to plot my own. Though I have no way of fixing it once I see how whacked it is.

Ed- You are now getting +/- 3 dB from 26 to 80 Hz from a ten year old design ... In other words, you did GREAT ! ... The small suck out at 84 Hz. is nothing to fret about... just enjoy !

I will definitely enjoy the fruits of my labor! Actually, you(Craig), Peter and Dennis deserve the credit.......all I did was input the filters you guys suggested.

Thank you!!

Does this mean you WON'T be selling my BFD back to me?

Maybe.....for twice the price!!;)

Good to hear the BFD worked out for you, in my opinion the BFD is one of the best investment for sub improvement.

From the movie fat chance. Nice try, Sherlock! . At least it's nice to know that if I ever try one again, I've got someone I can get to come over and help me set it up.

The best part about setting it up was posting the numbers here, and having the "experts" do all the thinking for me!!

Very nice work, everyone. Here's the obligatory graph :



Flipping your phase switch should help with that suckout at crossover...

It took some time (and about 8 filters) but I finally got the SVS PC-Ultra and BFD working together. Here are my results...

Given that my cutoff is 80Hz, I haven't concerned myself with the graph in the 80-150 Hz range.

Glad to be of service, and as I mentioned in my PM to you, I was amazed I was able guesstimate the filters accurately. If only I could find someone to pay me for this sort of luck.

Think there is a bit more to it than just luck Peter.

THAT is a heckuva graph !

Good Job Peter,
I guess when it's time to re calibrate my SVS pB2/Plus you better come over and help.. After all Antioch isen't any further to come than Tracy.. Ha Ha
Lee

The area below 20 Hz was a surprise to me. I haven't plugged any ports, so I expected a drop off at 20 Hz or so. The sub is sitting in the corner of a small room...perhaps that makes a difference. Anyway, I feel I used too many filters...but I am not sure it matters.

Dude, if it's that flat (and ok, for all you anti-graph people out there, sounds good), I don't think you did a darn thing wrong...

Just how many filters did you use? Regardless, if they resulted in a graph that flat from 16Hz (and probably lower!) to 80Hz, I don't think I would change a thing! Amazing in-room response.

You deserve a cold beer.

It took eight filters to get the results you see in the graph. I'm real happy with it...in addition to a flat response, the things sounds real good.

Jeez....I'm gonna have to upgrade my sub soon!

I will probably tweak the filters as well as play with the phase(0/180) and see how much flatter I can get.

I won't be getting much sub-25hz info though.

Rather impressive what a $100 toy can do.