Using BFD when amp has no "dedicated" sub out

[kumimajava]

I've been considering adding a BFD to my system - but I don't know whether I can make it work with my amp (Marantz PM7200). The amp has no "dedicated" sub-output (so I have to use high-level connects to the sub), but it does have a pre-amp loop.

could i just route the signal from my "pre-out" to the BFD, and then from the BFD back to the "pre-in" on my amp? would this adversely affect the sound-quality of my main (satellite) speakers?

If i understand correctly, I could use the BFD to cut/boost certain frequencies only - and leave the "upper end" untouched. Is this so?

thanks in advance.

[russ.will]

It depends on whether the pre-out/power amp inputs have to have jumpers between them during normal stereo operation. If they do, then the best bet would be to to get a single RCA Phono to Double RCA Phono adaptor to split the pre-amp output.

If there are no jumpers, then just use the pre-amp outputs.

I would do whatever it takes to avoid passing the signal through the BFD as whilst it's sampling rates are good enough for bass reproduction, they're not much cop for the higher frequencies that are reproduced by your main speakers. I feel the analogue>digital>analogue conversion could posiibly result in an unacceptable loss of transparency, that just isn't noticable in the bass.

The best bet would be to use an active crossover. Nimby is a wealth of expertise on this subject and if you do a forum search using those two words, there's a couple of threads discussing their use in detail. The good news is Behringher make one (CX2310) and at the last count it costs about £70 which is very cheap.

Russell

[kumimajava]

Thanks Russ!

The problem is this: firstly, yes the pre-out/in do have jumpers. Secondly, when I adjust the volume knob on the amp, the Pre signal strength is NOT altered. So I can't just "split" the signal & send part of it to the sub - because then the volu me of the sub would not change when I adjust speaker volume.

Could this be a solution (admittedly clumsy): set some constant "volume" on the amp, route the pre-out to the active-crossover (e.g. the CX2310), then feed the "high" output from the back to the main amp, and the "low" output to the BFD for sub-management. Then just "control the volume" via the gain setting on the x-over.

... seems like a lot of fuss. I suppose I should just switch amps & get one with a dedicated sub-out - but I just like the MP7200 too much.


Thanks again.

[russ.will]

Can you post a decent piccy of the back of the amp?

I can't help thinking that if the signal level from the pre-out is not affected by the volume control, then it's not a pre-out, but a processor loop, in which case, it's back to the high level input method.

Unfortunatley, the only EQ device I know of that can EQ the high level input method, is the Velodyne SMS-1 @ £400.

Russell

[kumimajava]

Indeed, you are correct - it does actually say "Processor" above the In/Out connectors. You can tell i'm not an expert at this... I assumed that processor/pre-amp outputs would be the same... but obviously not.

i attached a pic of the connections part of the amp (from the back), just in case.

... but the £400 for hi-level eq - for now - sounds quite scary. might just be easier getting a different amp. sigh.

Thanks, as always

[russ.will]

Oh, well! That's high level only then.

Russell