Comb Filtering?

[warnock]

Hey was just wondering if anyone could tell me if I placed x2 speakers side by side without them being perfectly arrayed is this the cause of comb filtering?

 

If so would it sound really bad etc.

 

Cheers

[mervaka]

that's exactly the sort of thing that causes comb filtering. it generally doesn't sound very nice..

[johndenim]

Depends on the box and dispersion.

 

What are we talking about here?

Any more info?

Or is this theoretical?

[Simon Lewis]

What do you mean or understand by "perfectly arrayed"? Boxes which have good pattern control but which are not physically placed correctly may well exhibit comb filtering. Boxes which exhibit poor pattern control or are not designed for arraying will tend to exhibit comb filtering when 'close' to each other whatever the placement.

 

There's some useful reading here...

 

Simon

[warnock]

Depends on the box and dispersion.

 

What are we talking about here?

Any more info?

Or is this theoretical?

 

logic xp15 - 90 x 60

[timtheenchanteruk]

yes, it sounds terrible, depending on where you are listening from to a greater or lesser extent.

 

I go to a few large holiday sites (with the kids) and some of the caberet bands, in the larger venues just use their normal kit, with an extra pair of tops plonked in there, sometimes not even a match to the originals and it sounds nasty. although TBH there has only been 2 bands in the lat 3 years of going to these sites that have had a nice sounding system, most seem to be too middish

[Matt Riley]

I was teaching a training session for some newbies the other day, and one of them raised the question why comb filtering didn't audibly happen on L-R systems? Neither me nor my acoustics graduate colleague could give a definitive answer - we suggested that it may be due to the actual relative lack of overlap in coverage patterns, the distance between boxes and the role of psychoacoustics. But I was wondering whether anyone else had the definitive answer?

[Shez]

I was teaching a training session for some newbies the other day, and one of them raised the question why comb filtering didn't audibly happen on L-R systems?

 

Where the coverage patterns overlap, it does happen. If you walk from one side of the room to the other, you should be able to hear it. For the definative explanation on interaction between speakers, have a look at Bob McCarthy's excellent "Sound systems: design and optimization". You'll wish you never asked!

[MattF]

Surely another big factor is that (generally) when listening to a stereo system from somewhere between the L and R stack, each ear is hearing a different source, and the effects and opportunity for cancellation will be greatly reduced.

[Rob_Beech]

I agree with what others are saying.

 

However just to go slightly OT I I may, with regard to bands in holiday parks. Sadly it's not as easy as it looks.

 

An example, last night I was working with Dr and the Medics, a regular client down in Devon. Now I've seen a copy of the contract with the details on it and it turns out its a venue that I've done before, once with them and a couple of times with various other acts. Now it's a wide room, it's not a big stage, it's maybe only 12m from the stage front to the back wall, but its nearly 3 times as wide, with the stage off centre to this (ie, it's twice as far to the right hand wall as the left). Very awkward to cover, especially when you have to keep sightlines, it's not a big stage and there's only 1 double and 1 half of a double of 13A sockets.

So, a system to suit, arrayable boxes for coverage and multiple subs positioned correctly for even coverage.

 

On arrival to the venue we were told the band were in another venue a mile up the road and there had been a ###### up on the contract. Not a problem, apart from it was a completely different shape.

 

Now this is difficult enough for a band that hires a PA from a PA company that can send out lots of different styles, types and arrangements of PA. A band who tour their own PA simply can't have something for everything.

 

 

Alot of Holiday Park type bands might be doing this for under £500. That's what you'd expect to see a PA alone in for at a medium level. There may be 4 or 5 of them, possibly more. There can often be £100 in a fuel bill on a gig like that, so that doesn't leave much per man to make a living from so sadly being able to rent storage for 3 or 4 different types of PA to suit different shapes of venue isn't possible, let alone when you run into issues like incorrect details on a contract. Plus alot of these bands can't afford an engineer, they'd all love one but sadly agencies have been so competitive that they've driven the price down so much that it's impossible for bands to afford an engineer and often impossible for them to afford what we as rental companies and engineers class as a good PA. There IS a definite element of not knowing how to get the most out of your system, but they're primarily musicians.