# Setting input levels on BFD



## veger69 (Mar 6, 2012)

Hey guys I'm trying to calibrate the input level on the BFD so it does not clip. I am doing this at reference level on my Denon 2809. So far I have had to put the BFD input on the +4dBu setting and also set the EXT IN SW Level on my Denon 2809 to 0dB (normal setting +5dB). I am still getting red Clip signals on the BFD during scenes like the Alien emerging in War of The Worlds. I think I can cut additional level in the "manual speaker levels settings" but this seems pretty drastic. With everything else I have read setting the output to +4dBu fixes the problem. At this point I'm going to have to raise my volume on my sub a great deal to match the output levels I had before. 

I was wondering if any Denon 2809 owners here run the BFD and if so is there another setting to lower the LFE output level? Should I lower it manually in the Speaker level settings? 

Thanks for any help


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## fitzwaddle (Aug 25, 2010)

I had a similar issue, although different receiver. My setup is Pioneer 1120K -> BFD -> QSC power amp -> THT passive subs. I ended up basically setting the gain on the power amp full up, then re-running MCACC to auto-set the sub out trim level. Worked for me, I could hit all the formerly problem scenes / demos (THX "Amazing Life" was the one that was the reliable test case for me) without clipping afterwards.


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## veger69 (Mar 6, 2012)

Quote from Brucek BFD Review
"MY TAKE: Correct, but the -10dBV sensitivity setting would always be used for home - line level equipment. This will ensure the system is receiving the spec'd "nominal" level. The spec indicates max input and output levels of +2dBV at the -10dBV sensitivity setting. This is quite accurate from my bench tests. +2dBV translates to 1.26vRMS; the yellow LED comes on at 1.2vpk and the red LED comes on at 1.5vpk and clipping occurs at 1.6vpk. Use the -10dBV setting. The +4dBu setting will result in nominal voltage swings far too low for the ADC system to respond properly."

Has anything changed since this review? I was only able to get the input levels not to clip or only occasionally flash red by setting the BFD to +4dBu and cutting LFE signal in my Receiver by -15dB. Then I had to give up setting the level at reference (0) on the Denon and lowered the volume to -3dB so in total a cut of -18db. 

I'm a little worried about the last statement above and why I have had to cut the input so much. I used U571, SUPER8, and War of the Worlds as reference and while U571 was not even hitting yellow SUPER8 and WOTW was still occasionally flashing Red for a second at the highest levels. 

If there is any additional info I can provide about my setup just let me know.


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## veger69 (Mar 6, 2012)

fitzwaddle said:


> I had a similar issue, although different receiver. My setup is Pioneer 1120K -> BFD -> QSC power amp -> THT passive subs. I ended up basically setting the gain on the power amp full up, then re-running MCACC to auto-set the sub out trim level. Worked for me, I could hit all the formerly problem scenes / demos (THX "Amazing Life" was the one that was the reliable test case for me) without clipping afterwards.


So by Gain you are referring to the sub volume control and if I understand correctly you then ran an Audyssey type program to set the sub trim levels in your Pioneer? 

When I calibrated my system with audyssey I adjusted my Sub gain until Audyssey set the SUB level at -1dB I believe the Audyssey guide recommends +-3dB. I’ll have to play with it some more tonight.


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## fitzwaddle (Aug 25, 2010)

veger69 said:


> So by Gain you are referring to the sub volume control and if I understand correctly you then ran an Audyssey type program to set the sub trim levels in your Pioneer?
> 
> When I calibrated my system with audyssey I adjusted my Sub gain until Audyssey set the SUB level at -1dB I believe the Audyssey guide recommends +-3dB. I’ll have to play with it some more tonight.


Since my subs are unpowered, the gain control is on the power amp driving them - but yes, for a powered sub it would be the sub volume control. And correct re: MCACC (Pioneer's calibration thing) being similar to Audyssey.

I wouldn't worry too much about the +/-3dB recommendation - as long as you're not ending up with something wacky like -20dB for sub trim, you should be fine.


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## veger69 (Mar 6, 2012)

The last thing that is bothering me is I calibrated my system with Audyssey witch should have set my volume levels to around 75dB at reference level (0 on the volume dial) but when taking mesurements with REW with the receiver set to 0 the overall volume is much higher to me it looks like 90dB, see graph link below.

http://www.hometheatershack.com/forums/bfd-electronic-equalization-devices/58456-midi-communication.html#post525507

I'm not sure why this would be but it may explain why I'm having problems trying to set the BFD input levels with my receiver set at 0. It could be I'm 15dB hotter than it should be.


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## fitzwaddle (Aug 25, 2010)

Did you take a measurement with an SPL meter, and then calibrate REW's level (using its SPL meter tool) with the level that the SPL (Radio Shack, Galaxy, etc.) meter showed?


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## veger69 (Mar 6, 2012)

Originally I had calibrated to 75dB connecting directly to my subwoofer. By setting the REW sweep levels and measuring with the galaxy until I hit 75db the running the SPL calibrate and entering the reading. 

The graphs linked were created after an Audyssey calibration. I then connected REW through the AUX input on my receiver. I set my receiver to 0 volume (reference) and then calibrated the REW SPL by entering in the value my spl was reading I believe it had increased to around 80-85 dB. Then proceeded with my measurements.


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

veger69 said:


> “...Use the -10dBV setting. The +4dBu setting will result in nominal voltage swings far too low for the ADC system to respond properly."
> 
> Has anything changed since this review?


Only that brucek was under the impression that low input levels would suck the bit rate of BFD’s 24-bit converters down to something substantially less than that. However, a converter’s bit rate is not defined by signal level. I also expect that another reason why he recommended the -10 dB setting was because he hadn’t heard of a receiver with a hot enough output signal to drive the BFD to clipping in +4 mode! I doubt he'd be alone with that one... 




veger69 said:


> I'm not sure why this would be but it may explain why I'm having problems trying to set the BFD input levels with my receiver set at 0. It could be I'm 15dB hotter than it should be.


Reference level and BFD levels don’t really have much to do with each other. I’d set the BFD levels for the maximum volume level you’ll ever use.

Regards, 
Wayne


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## veger69 (Mar 6, 2012)

Wayne A. Pflughaupt said:


> Only that brucek was under the impression that low input levels would suck the bit rate of BFD’s 24-bit converters down to something substantially less than that. However, a converter’s bit rate is not defined by signal level. I also expect that another reason why he recommended the -10 dB setting was because he hadn’t heard of a receiver with a hot enough output signal to drive the BFD to clipping in +4 mode! I doubt he'd be alone with that one...
> 
> 
> Reference level and BFD levels don’t really have much to do with each other. I’d set the BFD levels for the maximum volume level you’ll ever use.
> ...


Reference level is the loudest I would ever listen to my system thats why I used it not because its reference level. I'm offten at -5 or -3dB on the volume so I can get a few dB there. 

Wayne in your opionion then you don't see a problem with having to cut the LFE levels by -15 to 18dB on my Receiver? It will be a little hard to do since I don't have any one place I can cut that much but between the channel level settings and the LFE boost setting I should be able to do it.


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

No, I can’t see any harm in reducing your receiver’s sub output as needed. The only potential issue I can see would be if your sub is an “auto on” model that needs an input signal to trigger it on.

Something else just occurred to me: Do you have a lot of boosted filters set for your BFD?

Regards, 
Wayne


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## veger69 (Mar 6, 2012)

Wayne A. Pflughaupt said:


> No, I can’t see any harm in reducing your receiver’s sub output as needed. The only potential issue I can see would be if your sub is an “auto on” model that needs an input signal to trigger it on.
> 
> Something else just occurred to me: Do you have a lot of boosted filters set for your BFD?
> 
> ...


I don't have the actual filter here at work but it looks almost identical to the one linked above with my graphs


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## fitzwaddle (Aug 25, 2010)

veger69 said:


> I don't have the actual filter here at work but it looks almost identical to the one linked above with my graphs


So one +5 at 69.80


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## veger69 (Mar 6, 2012)

I will have to check at lunch the final filter I uploaded had 4 but it should be similar.


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

The BFD’s meters reflect the input signal + filter gain, so I was thinking that if you had a lot of boosted filters, or perhaps a single one with a severe boost, that would help account for the high meter readings. But it looks like the one boosted filter you do have is substantially offset by the -11 dB filter.

So – never mind. 










Regards, 
Wayne


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## veger69 (Mar 6, 2012)

Here is the final filters. The +6 filter and -11 filter is the same so I think you reply above still holds


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## fitzwaddle (Aug 25, 2010)

+6 at 70.65 and -7 at 72.35 seems odd


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## veger69 (Mar 6, 2012)

The original was done with 1/6 octave smoothing and REW came up with 5 filters. I tweaked it and removed 2 of the filters. 

For the last one I believe I removed the 1/6 smoothing and just let REW determine the filters it came up with 4 which was close to what I wanted so I just left it. I was not ready to connect the BFD at the time. I’ll take a look at it again. I think I’m going to recalibrate my REW levels to 75dB through the receiver and re-measure anyway. Should be able to dedicated a good chunk of time this weekend.

Thanks for all the help


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## veger69 (Mar 6, 2012)

after reading this post http://www.hometheatershack.com/forums/bfd-electronic-equalization-devices/14338-consensus-bfd-audyssey-house-curve.html#post126791

I think I understand the question Wayne asked in my other post
"That said, since you’ve mentioned using both Audyssey and the BFD, I’m kinda lost at this point as to what exactly is going on..."

To tell you the truth Wayne I'm not totally sure  
I was not aware of what exactly dynamic EQ did now that I know it is basically implementing its own House curve I may still try to tame any peaks or nulls that Audyssey does not address. I have a feeling though that if they are there it is probably due to Audyssey using 8 different locations for its EQ while my measurement is only at the main listening position. 

Is it possible to address Phase frequency issues with REW and a BFD? or would I be better off investing in something like the Anti-Mode 8033Cinema Precision subwoofer EQ?


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## marty1 (Jun 29, 2010)

Sorry just to confirm, have we confirmed that we can use the +4dbu studio setting for home use?

I have the same problem as in order to prevent my bfd from clipping I have to have the receivers subs trim at its lowest setting, -10db, in order to be able to watch loud action scenes at -10db on the recievers master volume (let alone reference level!).

I compensate by turning my power amps volume dials up to max but even then the bass is pretty lifeless.

I need to be able to turn my receivers trim up a lot more to get some decent bass.

So it seems that if it is okay, then the only way I can see is to use the studio setting.

Does anyones bfd cut the sound to the subs when the clipping occurs?

Regards

Marty


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

It’s no problem using the +4 setting. That’s what the switch is for, to shift the BFD’s operating range to accommodate low or high signal levels. +4 does increase the BFD’s noise floor substantially, but that’s not an issue with a subwoofer application.

Regards, 
Wayne


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## marty1 (Jun 29, 2010)

Wayne A. Pflughaupt said:


> It’s no problem using the +4 setting. That’s what the switch is for, to shift the BFD’s operating range to accommodate low or high signal levels. +4 does increase the BFD’s noise floor substantially, but that’s not an issue with a subwoofer application.
> 
> Regards,
> Wayne


Thanks Wayne :T

Just waiting to see if someone has the sound cut out when bfd clips?

Sorry to hijack the thread

Regards


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

In 10 or so years and several Forums helping people with the BFD, can’t say I’ve ever heard of that one. Fortunately, it’s a problem with an easy fix... 

Regards, 
Wayne


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## marty1 (Jun 29, 2010)

I must have a faulty one then :rolleyesno:

I did buy it preowned, I have only applied 2 large cuts to the measurement, both -36db at 30hz and 60hz and the sound does not sound even at all, even though it measures pretty flat.

Although the bass is a little heavier, I find the sound through the antimode much more punchy and smooth.

The bfd requires me to turn the trim on the receiver and the volume on the EP4000 pro amp up to max to get any descent bass volume so I'm guessing that is not right :rolleyesno:


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

marty1 said:


> The bfd requires me to turn the trim on the receiver and the volume on the EP4000 pro amp up to max to get any descent bass volume so I'm guessing that is not right :rolleyesno:


That’s because of the massive cuts you’ve applied. With two 36 dB cuts, the signal going out of the BFD is virtually nothing compared to what came in. So you’re having to make up for the lost gain elsewhere.

Regards, 
Wayne


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## marty1 (Jun 29, 2010)

Thanks Wayne, I'm moving my question to another thread as I've hijacked enough.

Apologies to the op 

Regards
Marty


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