My first REW graph, do I need BFD

[henry1234]

Just done my first graphs of my room with my tiny M&K KX10.

I don't need it to go low or loud as I have children & neighbours. I just want a smooth response so I hear a nice sound.

From my ears I was aware of a peak, it sounded fun for a little while in the new room but obviously not fun enough as I am now on this forum at 1:30am.

I have to sit against the back wall, hence the 50-70hz peaks.

Can a BFD help smooth out this graph, I have a chance to pick one up cheap tomorrow?

The sub is literally just above minimium volume setting on the dial.

[brucek]

You're being unkind to yourself by using such an exaggerated vertical scale.

Normally we use 45dB-105dB as the standard. This allows for a 75dB target measuring level with a +/- 30dB swing.

It's also best to measure the sub with the mains disconnected to determine the peaks caused by the sub alone. Once the sub is equalized, then the mains are added to get the best transition at the crossover.

Anyway, for sure the peak you have can be smoothed with a BFD very easily. You might also try moving your sub around a bit if possible to get the best response possible before equalizing....

brucek

[henry1234]

thanks,

I've changed the scales.

This was with only the sub connected, direct to the soundcard.

It normally connectes to my Lexicon DC-2 with crossover set to 120hz with M&K K17's as front speakers.

[brucek]

Yeah, you have a peak between 50-60Hz that could be easily eliminated. It's useful to look at your sub response 'in-situation' with the receiver and the crossover you normally use to see how it looks. An equalizer would connect between the sub out of the DC-2 and the sub amp, and is fairly easy to set up. You already know how to use REW.

brucek

[Wayne A. Pflughaupt]

Henry,

What kind of sub is this? Is it a budget model with a small driver? Judging from the fact that it rolls out fairly hard below 50 Hz, a relatively high frequency, that would be my guess.

If that’s the case, you’ll want to be very careful using the BFD, because equalizing a sub ends up placing additional demands on it. So you really need a subwoofer with headroom to spare.

Don’t mean to put down your equipment – just don’t want to see you damage it! The little 8” M&K sub I have for my computer speakers complained loudly with the low notes after I put a BFD on it!

That said, if your normal operation is at lower volumes, as you indicated, you should be all right.

Regards,
Wayne

[henry1234]

yes it is a small relatively small budget model:

http://www.progressive-av.com/produc..._specsheet.pdf

levels will always be low so I hope it's worth getting the BFD.

[Wayne A. Pflughaupt]

If your crossover point was the usual 80-90 Hz, I’d say you look pretty good and you don’t need a BFD. However, since you’re dividing at 120 Hz, the BFD could smooth out that raggedness between ~75-120 Hz. If you don’t try to boost the bottom end (below 50 Hz), and limit adjustments elsewhere to maybe no more than +/- 6 dB, you should be fine. If you overdo it, you’ll know because the sub will make all kinds of rude noises.

As an aside, I notice the spec sheet you linked said the KX extends to 35 Hz. M&K seems to exaggerate their low freq specs – my 8-incher was supposed to be good to 25 Hz; didn’t even get close.

Regards,
Wayne