# Adjusting levels on a BFD



## gperkins_1973 (Aug 25, 2008)

Hi there,

I am curious to find out if there is a way of adjusting the input levels (gain) on a BFD like the gain on an amplifier. When I connect my BFD in the chain my levels overall drop quite a bit and I have to increase my sub trim level up to get back to 80db for my sub (my preference).

I have it switched on the +4 setting but have tried switching from the -10 to the +4 and there is no audible difference at all.

So I am wondering if everyone has this problem when they put their BFD in the chain.

cheers

Graham


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

> I am curious to find out if there is a way of adjusting the input levels (gain) on a BFD like the gain on an amplifier.


Some equalizers have gain adjustments, but not the BFD. The input level has to be set externally, from the receiver's sub output.




> I connect my BFD in the chain my levels overall drop quite a bit


Since the BFD has no on-board level adjustments, that means the BFD is a unity gain device, meaning that what comes in is what goes out. However, any EQ filters employed will affect the output levels. Employing primarily gain-cut filters reduce the output signal.

It's typical to have to re-adjust the sub after EQ. That's because in many cases, there's a peak in the room. That peak is what you had previously based your sub level on (since it was the loudest thing you hear). Once you eliminate the peak, you perceive (rightly so) that the sub isn't as loud as it was. So you have to turn it up to compensate.

Regards,
Wayne


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## tonyvdb (Sep 5, 2007)

Are you going straight form the receivers unbalanced rca sub out tho the BFD? You may need to be using a Samson s-convert to properly convert the signal to a balanced output. even though the BFD has a switch to select -10db and +4db your signal may still be to low but this setting should be on the -10db setting and you must use the 1/4" input with TS connectors.


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## gperkins_1973 (Aug 25, 2008)

tony,

Yes I am. I will probably get one at the end of this week when I get paid and give it a go to see if it makes a difference. I have increased the sub trim level to get 80db with the radioshack.

I have from memory added 7 filters with most cutting around 7-9db with just one which has a boost of 8db. I will have a play with it tomorrow to see if I can do less cuts.

cheers

Graham


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## tonyvdb (Sep 5, 2007)

what are you running the level at on the receivers sub out setting?


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## gperkins_1973 (Aug 25, 2008)

Tony

-1db on the sub trim level. Gain on the EP4000 is on max.

These are the filters I applied:

Frequency BFD Gain Bandwidth
(REW) filters
24.50 25-2 -8 18
28.90 32-8 -5 6
33.20 32+4 8 7
42.00 40+4 -3 10
51.95 50+3 -7 11
70.65 63+9 -8 6
100 100 -9 7
176 160+8 -21 15

The reason for the last one is because there was a peak at about 175hz which I was concerned about.

cheers

Graham


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## tonyvdb (Sep 5, 2007)

ok but what about the receivers output? dont you have a level adjustment on that as well? (should be in the receivers user menu)


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## gperkins_1973 (Aug 25, 2008)

Tony,

Here's my graphs. 

Blue is sub only after Audyssey and no BFD

Pink is sub only after Audyssey and with BFD

Orange is Sub and speakers with Audyssey and BFD.

cheers

Graham


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## gperkins_1973 (Aug 25, 2008)

tony,

Not sure about that. Where would I look. I have never had to do that before.

cheers

Graham


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## tonyvdb (Sep 5, 2007)

What receiver are you using? it should be under the speaker level adjustments.

The BFD sure does a nice job of smoothing out the response, Looks good.


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## gperkins_1973 (Aug 25, 2008)

Tony
I have an onkyo 876

cheers

graham
_Posted via Mobile Device_


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## tonyvdb (Sep 5, 2007)

Ok the 876 menu is the same as my 805, go into the setup menu and under speaker level adjustments there is a setting for the sub you may want to raise that up from where it is. That will help allot.


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## gperkins_1973 (Aug 25, 2008)

tony

thats the sub trim level. I have that set on -1db which gives an spl reading of 80db on the radioshack. That is 5db hot at the mo. 

Perhaps Im too much of a basshead.

Graham
_Posted via Mobile Device_


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## tonyvdb (Sep 5, 2007)

Yes I understand but if you turn that up to about +6 and then turn the EP4000 amp down your levels will be the same you will just be sending a stronger signal to the BFD and thats what you want.


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## gperkins_1973 (Aug 25, 2008)

Ah I see what you saying now. I was told by behringer to have the ep4000 gain on max as it sends the full output of the amp to the subs and to trim the sub level on the onkyo. 

You can see how people get confused.

Graham
_Posted via Mobile Device_


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## tonyvdb (Sep 5, 2007)

Sigh, Behringer is giving wrong info. Obviously to high an input signal can clip the input but in your case I bet your not even close as the Onkyo at +12db (its highest setting is only outputting 1.0volts and the EP4000 wants 1.5v so I would think adding some gain to the signal coming in would be less noisy and give you allot more output. I dont ever recomend having the levels on an amp wide open, too much noise that way. What are the level indicators showing on the BFD when you have it the way you do?


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## gperkins_1973 (Aug 25, 2008)

say watchimg something like transformers 2 on volume -20 on the onkyo on the bass scenes I would probably see 3-4 green lights but mainly 3 on heavy bass scenees. Playing bassotronics I love you on the low low stuff I would see 4-5 on volume -25db but that is 11hz stuff.

graham
_Posted via Mobile Device_


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## tonyvdb (Sep 5, 2007)

You can get away with a bit more gain on the input signal to the BFD thats for sure. try about +4 and see what that gives you. back the gains on the EP to about 3/4 and go from there.


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## gperkins_1973 (Aug 25, 2008)

ok mate will do.
_Posted via Mobile Device_


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## Nuance (Nov 2, 2008)

Don't turn the subwoofer trim on the Onkyo up too high, else you might be sending a clipped signal all the way though to the speakers and subs. 

gperkins_1973,

Did you follow the BFD setup guide and find the clip level of the input signal from your receiver first? I have the Onkyo 805 and I used War Of The Worlds and Flight Of The Phoenix to find the clip levels of my receiver. To do this I put the BFD in bypass mode and turned the receiver volume as high as I'd ever listen (0.0), then adjusted the subwoofer level through the receiver until the red clips lights no longer came on steadily, with the orange lights staying solid during the loudest, deepest passages. Oh, don't do this with your subs and speakers on.  In my situation I ended up with the Onkyo's subwoofer level at -2. Once I finished EQing using the BFD, I level matched the subs to my mains by using the subwoofer gains (do NOT touch the subwoofer level on the subwoofer). 

The idea is to find the clip level of your input device, then back the subwoofer level off to just below that. This way you'll be sending the strongest signal to the BFD, but without said signal ever clipping. Once you apply your EQ filters those red clip lights should never come on again. And only after you've set the input level should you start the EQ process.


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