[ZooDog]

Hi all,

I've got a few pictures of my room located in my gallery: http://www.audiocircle.com/index.php?action=gallery;area=browse;album=276

The speakers are normally pulled out a few feet further from the wall.  These pics were taken right before my superbowl party so I had them pushed back so that everyone could see the screen.

Frankly, the system sounds pretty damn good as is, and there aren't any specific woes that I have, but I'm sure it could be better.  I'm wondering if there is anything that jumps out that should be treated.  The room dimensions are approximately 20 x 15 x 10.

Please let me know if there is any other information that would be helpful.

Thanks,

Tim

[Ethan Winer]

Tim,

> I'm wondering if there is anything that jumps out that should be treated. <

I see a bunch of stuff to comment on.

First, your listening position is very close to the wall behind you, and that's where the inevitable low frequency peaks and nulls are worst.

Most of your photos are close-ups of "gear" so I can't tell whether the loudspeakers fire down the long or short dimension. They should definitely face the long way into the room, again to get you farther from the rear wall.

As for treatment, I see none. All rooms need substantial bass trapping, and putting absorption at the first reflection points is equally important.

I hope this helps.

--Ethan

[ZooDog]

Thanks for the reply, Ethan.  

I should have mentioned in my first post that I am using a Velodyne   DD-15 sub to cover the bass <80Hz.  I don't know if you are familiar with the Velodyne DD subs, but they have built in EQ that allows one to essentially achieve flat bass response at the listening position.  So the low bass isn't a problem.

The speakers fire across the short dimension of the room, and this is the only way that I can have them set up.  

I will look into doing something with the first reflection points.  Do you think that some diffusors behind the listening position would be beneficial?

[ctviggen]

Well, one benefit to trapping bass is that it limits ringing.  If you were to look at a 3-d waterfall plot (my term -- I think it actually goes by another term), you could see that in an untreated room individual frequencies will have longer sustain.  What this means in practical terms is that a drum beat will last longer than it should.  Fast drum beats could even "overwrite" each other.  A flat frequency response does nothing to help with ringing.  As all of my realtraps are on stands, I'm going to post "before" and "after" waterfall plot.  However, I need to get rid of 60Hz leaking into the measurement, as the waterfall plot is totally messed up by having a huge peak at 60Hz that never goes away.  

Actually, your room looks great but is acoustically very hard to treat.  There are so many openings and there aren't many spots to place anything.

[Ethan Winer]

Tim,

> Velodyne DD subs, but they have built in EQ that allows one to essentially achieve flat bass response at the listening position. <

That's what you think!

As Bob explained, even if you use EQ to reduce the skewed response all rooms have, there's still the problem of modal ringing. But EQ is never a complete solution anyway. Yes, it can help to reduce modal peaks, but it does nothing for the deep nulls which are at least as damaging if not more so.

> Do you think that some diffusors behind the listening position would be beneficial? <

Probably not. Diffusors can be useful when they're far away from you, but the wall behind you is too close for diffusion. Absorption is a better choice there, especially if it's effective to low frequencies.

--Ethan

[Red Dragon Audio]

Hi Ethan,

At what point would diffusion be more useful?  10ft from the listening position? Is there some magical point or just a basic guideline to follow?

I saw a really cool mosaic piece of artwork the other day that was made with small boxes with painted leaves on them.  They were arranged in a geometric pattern on the wall and looked like a great way to integrated diffusion into a room while decorating it at the same time.

[Ethan Winer]

Ryan,

> At what point would diffusion be more useful?  10ft from the listening position? <

Yeah, somewhere around 10 feet, maybe even 8 feet. But understand that most rooms need absorption much more than they need diffusion. I think of diffusion as icing on the cake, and only if needed, which is not always. The point of diffusion is to break up flutter echoes and scatter early reflections but without damping the room. So if you have a thick wall to wall carpet and a lot of plush furniture, and the room already borders on being too dead, diffusion could be useful.

--Ethan

[ctviggen]

Hey Ethan,

I've been thinking about combining your traps with some diffusion.  If I could fit a diffusive structure (see: http://www.customaudiodesigns.co.uk/diffusers/diffract.htm) behind your traps, would there be any benefit to that?  A detriment would be that waves going behind the diffusive structure wouldn't be absorbed.  But waves that go through the trap to the diffusive structure would not only be diffused but I would think the aborption might also be improved.

[8thnerve]

Hey Ethan,

I've been thinking about combining your traps with some diffusion.  If I could fit a diffusive structure (see: http://www.customaudiodesigns.co.uk/diffusers/diffract.htm) behind your traps, would there be any benefit to that?  A detriment would be that waves going behind the diffusive structure wouldn't be absorbed.  But waves that go through the trap to the diffusive structure would not only be diffused but I would think the aborption might also be improved.

I'll let Ethan correct me if I am wrong as they are his products, but from what I understand the Real Traps have a non-absorptive front layer, so anything you put behind it will not have much effect, especially a diffusor which is expecting a direct wave.  If you use a diffusor, you should put it where a direct sound wave will hit it so that it can then scatter that energy effectively.

[Ethan Winer]

Bob,

> If I could fit a diffusive structure ... behind your traps <

As Nathan said, that won't do anything useful if it's behind the trap. Diffusion is mainly a mid/high frequency treatment, and none of that will get through our traps.

Also, bass traps work best in the room corners, and diffusion works best at key places flat on the walls. How large is your room? Generally speaking, the smaller the room, the more it needs absorption instead of diffusion.

--Ethan

[ZooDog]

I'm resurrecting this thread because I've sold some gear and I have a little money to invest in room treatments.

Ethan - I'm definiely interested in your Mondo traps for bass trapping.  How many would I need and where would you suggest I place them?

[Ethan Winer]

Tim,

> I'm resurrecting this thread because I've sold some gear and I have a little money to invest in room treatments. <

Thanks. Gotta keep your priorities straight! Room treatment first, then gear.

> I'm definiely interested in your Mondo traps for bass trapping.  How many would I need and where would you suggest I place them? <

You said earlier that your room is approximately 20 x 15 x 10. So you'll need at least four, and you can go up from there. I have 36 traps in my 25 by 16 by 11 living room home theater, but you don't need that many to get great results!

I always feel guilty telling people how much money they should spend. But that's really what it comes down to: How much you're comfortable spending, versus the kind of results you want. And for many people, it's not the cost but how many they can sneak past their wives.

--Ethan

[ZooDog]

Thanks for the reply, Ethan.

My budget right now is about $1,500, and I could add more in 3-6 months.  I forgot to mention that I do have some 2" Auralex foam at the first reflection points which seems to have cleaned things up a bit, but it was cheap and I could remove it if you think that one of your products would perform significantly better.  I remeasured my room and it is closer to 20x17x10, but I have floor to ceiling protrusions centered along the long wall that are about 8' long x 2' deep.

[Ethan Winer]

Tim,

> I do have some 2" Auralex foam at the first reflection points ... I could remove it if you think that one of your products would perform significantly better. <

No, not significantly better. A MicroTrap is about equal to three-inch thick good foam (not lousy foam like Foam by Mail sells). It's very common for people to already have foam when they come to us. So as long as it's high quality foam you can use that for first reflections, and get "real" bass traps to handle the manly job of solving bass problems.

> I remeasured my room and it is closer to 20x17x10 <

That doesn't change the basic recommendations. When you're ready to proceed, lets move this to email or you can call me on the phone.

Thanks.

--Ethan