BFD results.

Discussion in 'Home Theater Projects' started by Ronnie Ferrell, Nov 6, 2003.

  1. Ronnie Ferrell

    Ronnie Ferrell Second Unit

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    First I want to personally thank Anthony Gomez for his wonderful PEQ program. It has helped me out a ton! For me it was a "must have" for setting up my BFD.

    Man what a difference the BFD made in the sound of my room. We have added more furniture to the room and after moving my sub back in after giving it some clothes, I figured I would start from scratch again with my BFD. Spent about 2 hours tonight and came up with this using 5 filters. I am shooting for a house curve and not a flat response. This is measured from 10-100Hz. The vertical lines mark every 10Hz. The graphs are with RS Db Meter corrections applied.

    BEFORE BFD:
    [c][​IMG][/c]

    Simulated filters using PEQ:
    [c][​IMG][/c]

    After applying BFD filters:
    [c][​IMG][/c]

    Notice how close PEQ came to real world results! Not bad! FYI: Each filter was tweaked individually. I did not just set all of them at once. You have to tweak one at a time and remeasure the results. I did no less than 10 full sweeps and plots using the test tons I made and burnt to a CD.

    I have two bad holes at 70 and 90 but it is my room. If I move my meter a foot it will shoot up and flatten out at these dips.

    My room is a "room from hell" shape wise and this is the best it has EVER sounded. I am very pleased with it...... (at least for now [​IMG] )

    FYI: This is using a 122L sealed tempest sub so not much there below 20Hz.


    Ronnie
     
  2. Allen Ross

    Allen Ross Supporting Actor

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    nice, i should try the actual software instead of just tweaking to personal tastes
     
  3. Keith M.

    Keith M. Second Unit

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    where can one get a copy of this PEQ software?

    I plan on purchasing the BFD this week...
     
  4. Ronnie Ferrell

    Ronnie Ferrell Second Unit

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  5. Saurav

    Saurav Cinematographer

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    I have separate stereo and HT systems. Right now, I have L&R of the stereo going through my own summing circuit which goes to one (L) input on my plate amp, and the receiver's LFE out goes to the other (R) input on my plate amp. It seems funky to read about it, but it works fine, because at any given time only one of my systems is being used.

    Could this be made to work with the BFD? I looked through some websites, and it seems like the L and R 'engines' can be set independently. So if I kept my current summing circuit, I could just insert the BFD in front of the plate amp, and set things up for both movies and music. Is that correct, or am I missing something here?

    Thanks,
    Saurav
     
  6. Ronnie Ferrell

    Ronnie Ferrell Second Unit

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    Saurav,

    You are correct. For any given stereo filter, you can set both the left and right channels together with the same values, or you can set each independently of each other with different values.

    I heard of people using a BFD to tame 2 subs, both with different sets for each filters at the same time. You scenario would just be the opposite of that. Both are doable. Also the BFD has 10 banks of presets. So you have 20 mono banks (2 channels x 10) of 12 filter sets to play with! You can play with different sets of curves and listen how each one sounds by flipping between the presets.

    (Boy, I hope that makes sense!)


    Ronnie
     
  7. Saurav

    Saurav Cinematographer

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    I read about the presets, but if I could set up L and R separately, I could eentually settle on a single preset which would work for both HT and music. Though I see the advantage of different presets, I could have separate settings for LPs vs. CDs. Hmm.... now this is starting to get interesting [​IMG]

    The device itself has just one set of inputs and outputs, right? I mean, it might have different connector options, but there's no input selection - correct?
     
  8. Ronnie Ferrell

    Ronnie Ferrell Second Unit

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    Correct again. No input selection, only different input types. There is no RCA inputs or outputs. You have to use 1/4" mono phono plug to RCA adapters. Remember this is a piece of PRO gear.

    They don't lable the channels L/R it is labled Input 1, Output 1 and Input 2, Output 2.


    Ronnie
     
  9. Saurav

    Saurav Cinematographer

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  10. Wayne A. Pflughaupt

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    Saurav,

    That’s a pretty novel idea, using separate sends to the sub for music and movies. I’m surprised more people haven’t thought of it.

    You’re on the right track. Since you only have one sub, both BFD channels would be set identically. However, if you are using different crossover settings for each send, you could compensate for any response differences between the two.

    Also, many people like higher levels of bass for movies vs. music; the two channels could be set up for that, too.

    Regards,
    Wayne A. Pflughaupt
     
  11. Saurav

    Saurav Cinematographer

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  12. Wayne A. Pflughaupt

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    The BFD only has bandpass filters. With a little creativity you can set a filter to mimic a shelving filter for the purpose of creating a house curve (I can show you how to do that when the time comes), but it won’t be nearly steep enough to act as a crossover.

    Regards,
    Wayne A. Pflughaupt
     
  13. Jeffrey Stanton

    Jeffrey Stanton Stunt Coordinator

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    Howdy Folks:

    Could someone please explain to me how I get my sub's numbers INTO Anthony Gomez's spreadsheet? Do I have to import some files from someplace (where?) or can I just enter my frequencies? (Where?)

    http://www.pvconsultants.com/audio/eq/peq.htm

    Thanks,

    Jeff S.
     
  14. Ronnie Ferrell

    Ronnie Ferrell Second Unit

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    [​IMG]

    You click the "Measured Response" tab at the bottom of the workbook. Enter you measurments in the raw db column, select "RS calibation" from the drop down menu IF you used the RS db meter. and then go back to the BFD tab and see your graph.


    Ronnie
     
  15. Jones_Rush

    Jones_Rush Stunt Coordinator

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    Anthony Gomez,
    I wish I knew about your software in the past, it really would have helped me quite a bit.

    Anyway, since the BFD can only correct the frequency response mainly for one sweet spot in the room, I don't understand why you are not going all the way, and use a room corrction device. If you'll ebay your BFD, you could buy everything needed for room correction, and still have money left in your pocket (assuming you have a spare computer, at least a Celeron 400mhz).

    Bass frequency response in my room before room correction (I think it is even worse than yours):
    [​IMG]

    After:
    [​IMG]

    There was a big thread about it several days ago, which also shows the waterfall graphs.

    You can use room correction only for the bass frequencies, so it will give you a sweet spot which is more or less in the same size as using BFD, but the correction will much better, both for the frequency doamin, and time domain (which is not addressed at all, with the BFD).

    Btw,
    You don't have to shoot for a flat curve, like I did here, you can experiment with any curve you wish, which will be tailored using the same accuracy as the flat one above is.
     
  16. Wayne A. Pflughaupt

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    Jones, you’re saying this correction setup you’re using (save the computer) is only $120 or so?
     
  17. Jones_Rush

    Jones_Rush Stunt Coordinator

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    Yes Wayne, that's about all it takes. Pretty absurd, I know. Kind of like the ultimate DIY tweak. LoL.

    To be more specific, the entire list of devices one needs, except for a cheap computer, is this:

    1) 32bit Sound Card - I bought the M-Audio Revolution 7.1 sound card ($80 USD), which has an amazing DAC. Michael Barnes of nOrh used it in the last audio show, driving a high end setup.

    2) Measurement Microphone - I bought the ECM8000. Amzing deal for $40.

    3) Microphone Pre-amp with Phantom Power Suply - You can use just a Phantom Power supply, and use the Sound Card mic-in, but I recommend against it, if you want to get the best quality (The sound card's mic-in is usually bad with all cards, regardless of their cost). Anyway, I bought the Behringer UB802 ($50), which does everything, and has superb accuracy (I checked it in-loop with the sound card, and the results were extremely good).

    4) Radio Shack SPL meter - Recommended but not a must.

    5) Voltmeter with a low ACV scale - Recommended but not a must.


    To sum it all, if you have nothing from this list at all (but most people have at least one product from this list), it is going to cost you ~$200 USD. Now, to put things in perspective, for ~$200 USD, you are able to do full scale room correction. It's about 1/10 of the price of a dedicated device (true, I don't take in the price of the computer, but I assume most of you have a cheap one you can use). And also, consider the fact that if you don't like the results (even though I believe you will), still, you can return the products you purchased back for a refund, and even if you don't, most of these products might be useful at times, for any audiophile, no matter what he does.

    This is a CLASSIC DIY tweak. I believe that if some of you will decide to try it, and report good results like I do (and many, many other people I know do), BFD days will be over, and trust me, they shoud be over.

    True, using this tweak means you need to insert a full blown computer in loop in your audio system, but I think it's really about time, and well worth the trouble. If you like the result you will get, you could then buy quiet fans for it, so its noise won't be too obtrusive in the room, or you can put it insside a hush-box, or put it in a different room, and use a radio based remote. There are really many ways to make computer noise a non-issue, so don't let it put you off.

    Edit,
    Regarding the UB802 mixer, I found the measurements I did: (take notice that the results you see, are limited by the sound card's line-in. While they are still very good, the DAC performance of the card is better than what is shown in the graphs, it's just that the line-in input becomes a bottelneck at a certain point, which is more than enough for what we need for recording the test tones though), one last thing, only one channel of the sound card is being measured, and this is the reason that the left and right channels seems to be asymmetric :

    This is with the sound card in-loop (without the UB802):
    Here

    This is with the UB802 connected inside the loop of the sound card:
    Here

    You can see that the UB802 is very transparent, and also don't forget that the only task we need it to do, is transfer Sine Waves. In that case, the UB802 becomes an overkill, but I like overkills, it surely better than having doubts.
     
  18. Saurav

    Saurav Cinematographer

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    More questions:

    * What's the real difference between the 1100 and the 1124? 20-bit vs. 24-bit processing, right. How much of an audible difference does that make for bass?

    * Can the two channels be summed into a single output? That way I can send my LFE straight to one input of the plate amp (I don't really care about EQ for films), and use the BFD for L+R for music, with a single output going to the other input of the plate amp. If not, I'll keep my summing circuit. But it's in a pretty big box for the teeny amount of work that it does, and getting rid of it would be nice.
     
  19. Allen Ross

    Allen Ross Supporting Actor

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    I don't think you can find a 1100, unless you search Ebay, also i want to say the 1100 has only 10 filters where the 1124 has 12 filters, not sure though
     
  20. Saurav

    Saurav Cinematographer

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    Yup, it was on eBay that I saw it, and that's when I noticed that there were two different model numbers both being referred to as the BFD.
     

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