Any Thoughts on a 250 Hz long decay and how much more room treatment

[IWC Doppel]

Hi all,

I am starting to experiment with some more room treatment, just to lose a little more reverb and perhaps get nearer to 300ms, I am about to re EQ the subs, but the sound is currently pretty balanced, here are is my responses for the centre channel. I wonder that the 250 Hz spike is about and if its a problem, the room has no bass traps and some but not many GIK panels, I will add some fabric covered boards towards the back of the room fro light reflection and high frequency absorbtion, any thoughts ?

The main room modes are 34 and 68 Hz

 

[DanDan]

Best to measure L, R, L+R. If you post the .mdat here people can investigate it properly using zooming and other focus tools. That ring looks very very narrow. I wonder is it on both speakers?

 

[IWC Doppel]

I did a few measurements again here is the L+R, sorry stupidly I misread so didn't take the L, R. Ive added the centre. This is the central mike position. I will redo the bass EQ as I have changed bass Amos and not recalibrated. I did spend some time aligning and level matching the three subs so the bass was as good across a 2m wide seating area. All the EQ is though PEQ's using the Acurus, I have 4 PEQ's per channel including the three subs

Looks like the 250 Hz ring is more centre channel, this time not so bad, perhaps a slightly different mike position

 

[DanDan]

I am a bit lost in the complexity of the rig and how measurements are gotten so I will stick to first principles.
I would measure without Eqs engaged. I would leave the microphone in a central representative location.
Measure each speaker separately, and also the combinations. View LF up to say 1000Hz only. Use appropriate smoothing or none.

Again, the ring looks very narrow and visually doesn't seem any worse than several others in the mid. Also it seems very unlkely that the same ring will remain outstanding when several speakers are playing. And.... we have two ears.

 

[IWC Doppel]

Thanks for the input, if we ignore the 250 Hz peak what would the advice be on additional room treatment ?

 

[DanDan]

You need Bass Traps!

 

[Raul]

Check if it is a noise, read with no signal.
I appear to be constant

 

[IWC Doppel]

I have done a little more to dampen the high frequencies at the back of the room and will be experimenting with bass traps, these ar the RT20's for C, L+R,SL,SR. you can see the surrounds have less decay in the 200-300 Hz region. I am still trying to uncover the 250 Hz spike, I thought I had found it when I noticed that my naim amp cases have a ring, this 'ring' can be damped as there is a plastic tab by the fan exit to do this. But it's still there. I couldn't read the noise with no signal. I chose a bright red for the Sl and SR so it'd easier to see. I wonder if adding some damping behind the screen might be worthwhile, I have about 2-3" of space. At the moment there is hanging black fabric behind the screen

 

[IWC Doppel]

I've also EQ's the subs a little more, the average and individual seating positions over a 2m wide span, quite happy with this considering how difficult it's been ! My Xovers are 50/60 Hz

 

[IWC Doppel]

Definitely just the centre, I am also wondering if there might be a reason that my SL and SR have a different profile to the L, R I have adjusted down some 2 db below the L,R settings using pick noise and then adjusted by experimentation and ear. My LR are something like 2-3 db stronger to 1k Hz and 3-4db lighter 2k-20Khz. I know they are different speaker but they are consistent with these differeneces. I have averaged L,R and SL,SR

The L,R's are at the from which has a lot of velvet and material near, the back has much less fabric around. At the moment its sounding very good indeed, not sure this graph is making me feel very good though !

 

[IWC Doppel]

You need Bass Traps!

Without using large intrusive structures any suggestions where I might hide or do a nothing worthwhile for the bass like behind the screen (only 2" of room) or under the sofa the corner cupboard is full of films ?

Adding the rear velvet covered wooden panels has made some worthwhile audible differences not easy to see in the measurements a little more decay in the higher frequencies which has improved clarity and intelligibility, but I want to avoid too much additional panelling and I know bass need depth, I liked to the looks of the targeted GIK bass traps for 30 Hz and 70 Hz, but the 30 Hz is some 12" deep