# bfd output voltage



## exojam (Oct 28, 2006)

I was wondering if someone can assist me in a question I have. I have just placed a Crown XTi-1000 in my system for the subwoofer. According to the manual it needs 1.4 volts for "full rated power". I do have a BFD DSP100 in line before the amplifier. I have found the below information concerning the input voltage on the BFD. My question is, can anyone tell me if the output voltage from the BFD is either a constant 1.26 or 4.9? I am using a Denon 3803 to run everything. I cannot find the output of the sub preout in the Denon manual. I am just trying to match what the Crown is looking for. Thanks. 

BFD:
The -10dBv setting allows a maximum input level of +2dBV, which is ~1.26vRMS. The +4dBu setting allows a maximum input level of +16dBu, which is ~4.9vRMS. 

Crown manual:
Sensitivity (volts RMS) for full rated power at 4 ohms==1.4v


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## brucek (Apr 11, 2006)

> My question is, can anyone tell me if the output voltage from the BFD is either a constant 1.26 or 4.9?


The output tracks the input level of the BFD when no filters are applied. The maximum output is the same spec as the input spec that you show in your post. The operating range depends on the switch position. The largest output on the -10dBV position will be ~1.26 voltsRMS.

The Denon will likely output a typical +2dBV. This wouldn't be enough to clip the input of the subs amp, but would be close enough to be a good match.

Choose the -10dBV position in the BFD and you're good.

brucek


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## exojam (Oct 28, 2006)

Bruce,

Thanks for the reply. That is what I have it at now (-10). I just wanted to verify I would be OK.


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## eyekode (Jan 19, 2008)

Have you tried to use the parametric EQ in your XTI? I was thinking about going this route and skipping the BFD...


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## imbeaujp (Oct 20, 2007)

eyekode said:


> Have you tried to use the parametric EQ in your XTI? I was thinking about going this route and skipping the BFD...


Yeh, why using the BFD when there is a built in EQ in the crown ?


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## exojam (Oct 28, 2006)

I am no longer using the BFD with the Crown. It seems to me, even though I have not been able to measure the output from the sub out on Denon, that the Crown is getting enough input. I have not starting using the eq in the Crown at this time. I have just not had time to mess around it with yet. I hope to be able to soon though. The reason why I had been using the BFD to the Crown was an attempt to get a close to the 1.4v it needs to run a full output.


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## eyekode (Jan 19, 2008)

When you get around to it let us know how it turns out! Right now I am considering the crown as an alternative to the BFD + EP2500/1500 (I don't really need that much power and Crown has an excellent rep).


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## exojam (Oct 28, 2006)

Eyekode,

You can check out this link over the Crown forum where this is talk about EQ with the XTi. I hope this is allowed to be posted. You may need to create an account (free) over there to read it but it is a good place to start. You will need to download the System Architecture program to use the EQ but it is easy and pretty cool to mess round with.

http://www.crownaudio.com/forums/index.php?showtopic=1976


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## imbeaujp (Oct 20, 2007)

Wow, it seems to be a verry powerfull option !!!


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## eyekode (Jan 19, 2008)

exojam said:


> Eyekode,
> 
> You can check out this link over the Crown forum where this is talk about EQ with the XTi. I hope this is allowed to be posted. You may need to create an account (free) over there to read it but it is a good place to start. You will need to download the System Architecture program to use the EQ but it is easy and pretty cool to mess round with.
> 
> http://www.crownaudio.com/forums/index.php?showtopic=1976


Thanks! This is actually the thread that got me interested in the XTI line. The only issue I see on paper is that you cannot set the low shelf filter lower then 20Hz... but you cannot do that on the BFD either right?

I was just hoping to hear from someone that has actually tried to do this with an HT sub. The Crown forum is mostly populated by pro-sound guys who could care less about < 20Hz. Actually I don't really care about flat response below 20Hz either, just want to protect my driver. Would have been slick to be able to do it with one box.


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## exojam (Oct 28, 2006)

Please excuse my ignorance but I am not really familiar with the term “low shelf filter” (even tough it is probably known to everyone else). If by that you mean is 20 Hz the lowest you can set any filter on, either lowering or raising the db, than I believe you a correct in that, that is the lowest the BFD can do also.


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## eyekode (Jan 19, 2008)

exojam said:


> Please excuse my ignorance but I am not really familiar with the term “low shelf filter” (even tough it is probably known to everyone else). If by that you mean is 20 Hz the lowest you can set any filter on, either lowering or raising the db, than I believe you a correct in that, that is the lowest the BFD can do also.


A shelf filter is a filter with a frequency response that has a "step" shaped response: http://en.wikipedia.org/wiki/Filter_design

This could be useful for protecting a ported subwoofer if the frequency could be set low enough.

I thought the Crown XTI series amps had these for low-pass/high-pass. 
But reading the manual I don't see it now...


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

Here’s what a shelving filter “looks” like. IMO, they are not suitable for driver protection. Stick with a high pass filter.







​



> Thanks! This is actually the thread that got me interested in the XTI line. The only issue I see on paper is that you cannot set the low shelf filter lower then 20Hz... but you cannot do that on the BFD either right?


The BFD has no shelving function.


Regards,
Wayne


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## exojam (Oct 28, 2006)

Interesting, thanks for the picture. I am sure I have seen the term before but had no idea what one was.


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