My Servo 15 response.

[JIT]

Finally got round to charting my Servo 15's response.

[bob1]

That dip at 40hz is HUGE or did you want it like that?

[JIT]

I know, this is with the Servo placed in the front left corner of my room behind and to the left of my front left speaker. When i get a chance i'll move it more towards the centre between my fronts and see what readings i get there.

I'm not using any EQ on the sub and have the crossover on my receiver set at 80Hz.

[Supra]

What did you use to get your measurements, I have Avia and the sub sweep is just to fast for me to get accurate measurements.

I know from the spl readings that I have a few dips, but charting them would seem a nightmare at the moment.

I have downloaded some test tones but these are in mp3 format. I have aslo mislaid these and can't remember where I aquired them from.

Even with the dips it sounds and FEELS excellent.

[JIT]

Look here - http://www.snapbug.ws/bfd.htm

There are links for tones and the Excel chart plus information on how to do everything.

[Supra]

Thanks JIT, more experimentation for me.

I will post my chart once I have carried it out.

[JIT]

It will be interesting to see what your dual Servos produce.

[Supra]

Here we go, quick test done with kids running in and out. Amp set to -21db to get spl to read 75db on first signal, if that is understandable.

I have tried to attach an image here

[Supra]

I know the dips are all over the show, but it still does feel good with movies.

A few more tweeks and a BFd should sort it out, hopefully.

The subs are in a open plan living area, can't be bothered to work ou the volume, it does measure 28ft x 32ft roughly.

Both subs are located between the front two speakers.

And It was a quick test, i didn't unplug the main speakers, just done the test with all speakers. I just scanned the instructions from the site you pointed me towards JIT.

The graph is with the adjustments made for the SPL.

[Ettepet]

Keep in mind that it is always better to reduce peaks by moving the sub than trying to do it all through a BFD. "Room-boom" isn't just increased SPL of a certain frequency range, it is also distortion. The echo's causing the increased SPL arive later in time.

[Nimby]

Supra

Is it just concidence that you have a big trough at 80Hz?

Are you crossing over just there?

Try making phase adjustments and retest

Nimby

[Supra]

Spot on Nimby, I have moved the subs aprt by 17ft and the graph pattern is pretty much the same.

I have plotted a graph for one sub and the pattern is the same, for both dips and picks in each case.

Will try phase adjustments, x over at 40 and set my mains to large. keep the others small.

Am also moving the subs back in between the fronts as the pattern doesn't really change.

how the hell do some people fet such staright lines. By the way the only phase adjustment i can do is on the amp, i do not have an x30.

[stevegreen]

JIT, I did a similar exercise a while back with my Rel Q200 and posted my charts. I was told by a certain member that the dip i had at 40hz was robbing me of a lot of 'punch', 'slam' whatever you like to refer to it as.

It may be worth having a look to see what you can do about yours as that is quite a hole you have there. Mine was relatively easily fixed by changig the amps settings to set the main speakers to small. I also moved the sub into the corner.

HTH

[Supra]

Changed crossover to 60, it has helped, the dip is not as pronounced, but is still there. It gets slihghly worse as it reaches 100.

I will say I have pitched ceiling in the part of the room the subs are situated, could this be causing it.

It is all wooden flooring and wooden blinds, I suppose some form of room trestment, rug etc, will probabaly be better.

sorry to jump onto your thread JIT.

[Gordon @ Convergent AV]

When you say you moved them a further 17ft apart do you mean equidistant to each other as before. IE if you were to place a sub in the mid point between the two at the first locations and the second locations would this central ghost sub be in same spot?

The dip at 80Hz looks too big to just be a phase error due to xover. I think there is more than that happening.

G