# BFD L & R engine as presets?



## russ.will (May 10, 2006)

Some people use Hifi integrateds to power their front L&R speakers, feeding them from their AV receivers pre outs. They do this to keep their CD/LP chain free from AV impurity.

The question is - If you have a sub without separate high and low level crossovers, can you feed the Left Engine the LFE channel, whilst feading the Right Engine a hifi pre-out signal. This would allow the hifi boys a suedo dual crossover arrangement as they could tailor filters to roll the sub in at say 30Hz because they're running their speakers full range. It would give you effectively two presets on the BFD - one for AV and one for Hifi.

Is this clear? Am I missing something really obvious?

Russell


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## brucek (Apr 11, 2006)

> Some people use Hifi integrateds to power their front L&R speakers, feeding them from their AV receivers pre outs. They do this to keep their CD/LP chain free from AV impurity


I'm afraid I don't know what this means. Could you explain?

I don't really understand the question, but if you're wondering if the BFD's two channels are completely discrete, the answer is yes.. 

brucek


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## russ.will (May 10, 2006)

Sorry I'll clarify.

Some people (the mate I'm asking this on behalf of) have high quality 2 channel hifi. To maintain the quality of their stereo playback AND have 5.1 surround they power their center, surround left & surround right speakers from the AV amp, but take the front left & right output from the pre outs of their AV amp and feed it into a spare input on their stereo amp - treating it as a power amp for the purposes of AV.

The friend in question is looking into a BK Monolith DF sub (see Ilkka's test), but the problem is that it has high & low level inputs, high & low level gain controls, but only one crossover control. To save faffing around with the crossover control (and because he should be EQing anyway with a sub this size) I was wondering if the BFD as well as being used in the normal AV way, could use the spare engine to take a full range signal from the pre out of the stereo amp and then set up a set of filters on the spare engine. He'd then have an AV preset on one channel and another preset on the other channel.

Hope that's clearer, but your answer answers my question anyway.

Many Thanks

Russell


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## brucek (Apr 11, 2006)

> could use the spare engine to take a full range signal from the pre out of the stereo amp


But wouldn't the signal that was split from the two channel system be stereo (two channel). How would you feed this to a single channel of a BFD without a combiner?

Or am I still not with it? I assume the term "stereo amp" means integrated amp.

brucek


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## russ.will (May 10, 2006)

This is the sort of questioning I want to know. Stereo integrated amp, or stereo pre/pro, it makes no difference.

What would be the problems with combining the stereo signal from a hifi pre-amp into a single mono input ie, the reverse of a single phono to two phono splitter? I hadn't thought of this problem, or even if it is a problem.

Russell


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## brucek (Apr 11, 2006)

> What would be the problems with combining the stereo signal from a hifi pre-amp into a single mono input ie, the reverse of a single phono to two phono splitter?


Splitting a line level signal with a simple Y-splitter cable adapter is completely different from the reverse situation of combining two outputs into one mono signal.

If you used a Y-splitter cable adapter in reverse you would essentially be shorting the two outputs of the pre-amp together - a real no-no.....

The only way to properly do this would be to purchase a combiner specifically designed to carry out this task. You can build your own from passive components, but it's not really desirable. An active device is required for proper isolation of the channels.

brucek


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## eddthompson (Aug 19, 2006)

or just get another bfd :laugh: 

or a deq2496, which im planning on experimenting with for my mains.


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## russ.will (May 10, 2006)

brucek said:


> Splitting a line level signal with a simple Y-splitter cable adapter is completely different from the reverse situation of combining two outputs into one mono signal.
> 
> If you used a Y-splitter cable adapter in reverse you would essentially be shorting the two outputs of the pre-amp together - a real no-no.....
> 
> ...


:T 

Russell


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