# Audyssey with BFD - input levels?



## ToBeFrank (Feb 27, 2010)

I'm curious how you guys using the BFD with Audyssey set the sub trim (input level) for the BFD? My plan is to get a flat response with the BFD first. I'll set the sub trim per the BFD guide. However, when I then run Audyssey, it will change the sub trim, which changes the input level to the BFD. Is the solution to use the volume nob on the sub such that when Audyssey runs it ends up with the same sub trim as I configured for the BFD? That seems like not an easy thing to do.


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## corock (Sep 7, 2009)

What you're trying to do with the BFD is cut or boost individual frequencies so that they are all equal or flat. Don't worry about the trim level because that just changes what spl your frequency response is measured at. Audyssey will then change the trim so that the sub spl is equal to your mains, blending the two.


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## ToBeFrank (Feb 27, 2010)

corock said:


> Don't worry about the trim level because that just changes what spl your frequency response is measured at.


Not according to the BFD guide. I need to set the sub trim level on the receiver so the BFD doesn't clip and also to achieve the most dynamic range.



> Auyssey will then change to trim so that the sub spl is equal to your mains, blending the two.


Exactly, it will change the receiver's sub trim from what I had set for the BFD. This is the problem I'm asking about. How do I get around it? It seems to me the only way is to use the volume knob on the sub, but I thought I'd ask the guys here that are using both the BFD and Audyssey how they do it.


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## corock (Sep 7, 2009)

ToBeFrank said:


> Is the solution to use the volume nob on the sub such that when Audyssey runs it ends up with the same sub trim as I configured for the BFD? That seems like not an easy thing to do.


You want your gain on the sub to be at a reasonable level so that the adjustments Audyssey makes falls within its capabilities. As an example...if you have a powerful sub and you have the gain set at 3 o'clock on the dial then Audyssey is going to try to trim the out of it so it doesn't overpower the mains. But, AV receivers will have limits like -12 to +6. So with the gain on the sub amp that high Audyssey will bottom out the trim at -12 even though it should probably be lower. 

You may have to experiment with the gain, after you've created a flat response with the BFD, so that its in a position that Audyssey can set the trim within that -12 to +6 range. I think most guys have the their sub gain between 9 and 12 o'clock.


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## corock (Sep 7, 2009)

Your taking your frequency response measurements at 75db. You can acheive that spl, no matter what the trim level is, by adjusting the volume on your receiver. You won't clip a BFD at 75db.

One of Audyssey's jobs is to set the sub trim level, so you can't prevent it. However, you can manually adjust the trim after Audyssey has made that adjustment.


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## ToBeFrank (Feb 27, 2010)

I mean no offense by this, but I don't think you're understanding the issue. Anyway, I think the solution is in my original question... set the sub volume knob such that Audyssey makes as little as possible change to the sub trim (BFD input level) as possible.


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## corock (Sep 7, 2009)

No offense taken, I've been exactly where you are. I'm probably not as good at explanations as some of the guys here, I'm just trying to help out until bruce or wayne chime in. (Bruce Wayne, there's something ironic about that). 

Anyways, the point I'm trying to make, and somebody can correct me if I'm wrong, is the trim level isn't a big deal before all your adjustments are made with the BFD. The input to the BFD is ultimately controlled by the volume on your receiver. The role of the trim level is to balance or blend your speakers with each other. That needs to be done after you've set your curve with the BFD because the filters you put in with the BFD change the output of your sub, thus the trim needs to be adjusted.


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## Wayne A. Pflughaupt (Apr 13, 2006)

ToBeFrank said:


> I'll set the sub trim per the BFD guide.


 Not the best idea. Everything I see on the pro audio / recording forums tells me that it’s better to leave some headroom, rather than maxing out the input levels. There is only 1/10 volt difference between the point where the red clip LED lights up and actual clipping sets in. It’s best to leave some headroom – set the levels to register something like -10 dB. You never know when you might drop in some DVD that has higher bass output than your "reference" disc. 




> Exactly, it will change the receiver's sub trim from what I had set for the BFD.


Are you saying that once Audssey sets the sub level, you can’t go in and manually change it? Not that it matters a lot; if you’re registering any kind of decent signal on the meters, you’re fine.

Regards,
Wayne


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## corock (Sep 7, 2009)

Hey Frank, I figured out we are talking about the same thing, just going about it two different ways. 

You see, when you adjust frequency levels with the BFD you are changing the output of your sub. Now you have bring that output back to a level that match your main speakers. 

Your idea is to do that by adjusting the gain on your sub's amp. If you get it right Audyssey will see the outputs matchs and won't change the trim level. That's a lot of trial and error and re-running Audyssey. 

I'm suggesting if you leave the sub gain alone Audyssey will automatically match the sub and main speaker levels by adjusting the trim levels. No guess work, no re-running Audyssey over and over. 

Changing the trim level after you've set the BFD filters is not a bad thing. It doesn't negatively affect the curve you've created with the BFD.

So, you can do it either way. If you still feel that the trim level has to be exactly the same as before you made adjustments to the filters then the path your on will work with some extra work, just don't go extreme with that sub gain.


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## ToBeFrank (Feb 27, 2010)

Wayne A. Pflughaupt said:


> Not the best idea. Everything I see on the pro audio / recording forums tells me that it’s better to leave some headroom, rather than maxing out the input levels. There is only 1/10 volt difference between the point where the red clip LED lights up and actual clipping sets in. It’s best to leave some headroom – set the levels to register something like -10 dB. You never know when you might drop in some DVD that has higher bass output than your "reference" disc.


Yes, I was planning to leave some headroom. How much, I don't know yet.



> Are you saying that once Audssey sets the sub level, you can’t go in and manually change it?


Yes, I can, but then that affects Audyssey. I want it to be configured for reference.



> Not that it matters a lot; if you’re registering any kind of decent signal on the meters, you’re fine.


Right, but setting the input level lower than necessary affects resolution. Whether that makes an audible difference or not, I don't know.


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## hjones4841 (Jan 21, 2009)

ToBeFrank said:


> I'm curious how you guys using the BFD with Audyssey set the sub trim (input level) for the BFD? My plan is to get a flat response with the BFD first. I'll set the sub trim per the BFD guide. However, when I then run Audyssey, it will change the sub trim, which changes the input level to the BFD. Is the solution to use the volume nob on the sub such that when Audyssey runs it ends up with the same sub trim as I configured for the BFD? That seems like not an easy thing to do.


I had far better results with running Audyssey first, then using the BFD to smooth out the sub. I tried it both ways and ended up with some rather strange looking curves if I ran Audyssey last. Not sure what was going on, but by far the flattest response was BFD last.

The way I set the BFD was to run the system to almost the max on a LFE heavy blu ray, then set the AVR's sub channel level so that the BFD LEDs barely got into the red, regardless of where Audyssey set it. You can then set the sub amp's level control if needed to match the other channels.


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## gperkins_1973 (Aug 25, 2008)

Me too! Defo Audyssey first and BFD last. I had to same problem.

cheers

Graham


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## ToBeFrank (Feb 27, 2010)

I've read of people having success both ways. I only need a couple filters to get rid of a couple modes so I'm going to try the BFD first. If that doesn't work I'll try it the other way.


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## trevorst (Apr 6, 2010)

I just picked up a new Onkyo receiver last week and have ran the Audessey setup several times. Although I am very happy with the results for imaging and surround aspects, the bass does not come close to what I had with my BFD setup. So yesterday I decided to put the BFD back in the signal chain.
Wow have things changed since I setup the BFD with my Harmon Kardon about 10 years ago. The room wizard looks fantastic. 

Those that are running Audessey did you find that it did very much to the bass in taming those boomy peaks ???

Also are there any good house curve files available ??? That aspect was just being discussed when I last worked on the BFD.


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## ToBeFrank (Feb 27, 2010)

trevorst said:


> Those that are running Audessey did you find that it did very much to the bass in taming those boomy peaks ???


Yes, I was a able to kill modes that Audyssey didn't touch. Not completely of course, but a massive improvement.



> Also are there any good house curve files available ??? That aspect was just being discussed when I last worked on the BFD.


I don't use a house curve. I let Audyssey set up it's curve dynamically based on level (Dynamic EQ). It's really the only reason I'm using Audyssey.


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## trevorst (Apr 6, 2010)

ToBeFrank said:


> Yes, I was a able to kill modes that Audyssey didn't touch. Not completely of course, but a massive improvement.
> 
> 
> 
> I don't use a house curve. I let Audyssey set up it's curve dynamically based on level (Dynamic EQ). It's really the only reason I'm using Audyssey.


Thanks...
I set mine up yesterday and got the same results you describe. My room has some issues at certain freq that cause terrible vibrations and Audessey didn't touch them. I was able to tame them way down with the BFD, also noticed the Audessey curve.


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