Equipment Between Speakers

[Sir Terrence]

I'm calling you out on this one. Quit talking out of a book and do the experiment. It's easy enough to try. Betcha' hear more than "mostly bass frequencies " and you won't have to measure them to find out.

I have done it with a RTA, and there was nothing happening back there except bass and some midbass frequencies. Most speakers(once again except Planars and ribbons) are not omni-directional at all frequencies, and this is widely known information(except maybe to you).

You were making an assumption I was talking out of a book and not out of experience. This kinda makes your "calling me out" seem kind of foolish.

Your response is exactly what happens when you don't have the "book" or its knowledge.

 

[Sir Terrence]

I did this last night after reading this thread just to see for myself. And since I'm working on some DIY dipoles I've been curious to hear just what's going on behind a forward firing/flat front baffle speaker. I have JBL L100t3s that stand about two and a half feet from the front wall with a floor to ceiling absorption panel directly behind each speaker. There are also numerous panels out in the room plus superchunk corner absorbers. Any high or mid frequencies I heard were severely muffled....almost like if you disconnected the tweeter and were just listening to the mid and woofer. Any chance when you hear highs behind your speakers you're just getting reflections from your room?

Your last statement is correct!

 

[Sir Terrence]

And I'll disagree with that statement - unless you are talking about directly interacting with the front wall.

I am talking about DIRECTLY interacting with the wall.

I use 2 acoustic absorption panels (mid to upper frequencies) on the wall between my speakers - they absolutely DO make a difference and it's readily apparent to anyone who listens with/without. First-person observation, not text-book explanation although I'm sure the text-book explains this if you look beyond 'direct' effect and consider the whole room which in my opinion you have to do - it's a system.

Those two panels between your speakers are absorbing mid high frequency reflections coming from other surfaces towards them. Unless your speakers are omni-directional at all frequencies, they are not mean't to absorb what is coming from the speaker at those frequencies.

 

[RickeyM]

Let me clarify a couple of points. First, no you aren't likely to hear any "highs" directly from a speaker listening behind the speaker. Unless it's omni-polar, di-polar or bi-polar that is. What you will hear a lot of lows and mids. Just how much of the mids you hear directly from the speaker is somewhat affected by the speaker's baffle width. Please forgive me if anyone assumed I was talking about full range sound because I didn't specify a particular frequency range.

Any chance when you hear highs behind your speakers you're just getting reflections from your room?

Did the experiment again with a pair of Rat-shack Pro-x88av's playing into an absorber panel spaced about 18" away. Again, no highs, just lows and mids.

I have done it with a RTA, and there was nothing happening back there except bass and some mid bass frequencies.

So you're test and my test agree, no? So let me qualify the statement in my post. If you have monopole speakers that allow a fair degree of their mids to be heard behind them, allowing this sound to reflect off of an untreated wall will color the sound.

Most speakers (once again except Planars and ribbons) are not omni-directional at all frequencies, and this is widely known information(except maybe to you).

You were making an assumption I was talking out of a book and not out of experience. This kinda makes your "calling me out" seem kind of foolish.

Your response is exactly what happens when you don't have the "book" or its knowledge.

Well ya got me there. It was foolish of me to assume that you were talking out of a book instead of from experience. Just like it's foolish of you to assume what knowledge I have.

 

[RickeyM]

Those two panels between your speakers are absorbing mid & high frequency reflections coming from other surfaces towards them. Unless your speakers are omni-directional at all frequencies, they are not mean't to absorb what is coming from the speaker at those frequencies.

Um, how exactly do you stop those panels from absorbing "what is comming from the speaker at those frequencies"? You know, the mid & hi frequencies you already said can't come from the speaker :scratch2:

 

[Sir Terrence]

Um, how exactly do you stop those panels from absorbing "what is comming from the speaker at those frequencies"? You know, the mid & hi frequencies you already said can't come from the speaker :scratch2:

When a speakers fires into a room, it creates reflections as the sound bounces off the sidewalls, rear walls, and ceiling. That is what the panels are absorbing.

What I stated is "coming DIRECTLY" from the speakers.

 

[Sir Terrence]

So you're test and my test agree, no? So let me qualify the statement in my post. If you have monopole speakers that allow a fair degree of their mids to be heard behind them, allowing this sound to reflect off of an untreated wall will color the sound.

No argument here.

Well ya got me there. It was foolish of me to assume that you were talking out of a book instead of from experience. Just like it's foolish of you to assume what knowledge I have.

I didn't assume that you had any knowledge. I just noticed what knowledge was missing in your post. The devil is in the detail, which makes the detail so important.

 

[RickeyM]

When a speakers fires into a room, it creates reflections as the sound bounces off the sidewalls, rear walls, and ceiling. That is what the panels are absorbing.

What I stated is "coming DIRECTLY" from the speakers.

So how do you account for the people who've stated that their sound improved by pulling the speakers away from the front wall. Shouldn't it make them sound worse by putting them closer to those reflecting points on the side walls, ceiling and rear wall.
BTW, just how much sound gets reflected from the side walls & ceiling back to the front of the room? Sound reflected off the rear wall I get, but even that is affected by the time delay generated by the trip from the speakers-to the wall-back to the front wall and (unless absorbed or diffused) back to the listeners ears. Mono-pole speakers of course.

 

[RickeyM]

Originally Posted by RickeyM

So you're test and my test agree, no? So let me qualify the statement in my post. If you have monopole speakers that allow a fair degree of their mids to be heard behind them, allowing this sound to reflect off of an untreated wall will color the sound.

No argument here. QUOTE]

So you're agreeing with me but you still say I'm wrong :headscrat

 

[Sir Terrence]

So how do you account for the people who've stated that their sound improved by pulling the speakers away from the front wall. Shouldn't it make them sound worse by putting them closer to those reflecting points on the side walls, ceiling and rear wall.

By moving a speaker away from the front wall, bass frequencies are not reinforced as efficiently as they would if they were very close to the front wall. Keep in mind, the corners have the loudest resonances in rooms. The further you move them away from there, the less efficient those resonances are stimulated.

BTW, just how much sound gets reflected from the side walls & ceiling back to the front of the room? Sound reflected off the rear wall I get, but even that is affected by the time delay generated by the trip from the speakers-to the wall-back to the front wall and (unless absorbed or diffused) back to the listeners ears. Mono-pole speakers of course.

The first reflections are usually from the floor right in front of the speakers. The engages the ceiling as those reflections bounce around until they become inaudible. Based on the dispersion pattern of the speakers, axial, tangential and oblique reflections also occur.

It is impossible to know how much sound is reflected to the sides, ceiling or back of the room until you actually sit speakers in the room, and measure them.

 

[Sir Terrence]

Originally Posted by RickeyM

So you're test and my test agree, no? So let me qualify the statement in my post. If you have monopole speakers that allow a fair degree of their mids to be heard behind them, allowing this sound to reflect off of an untreated wall will color the sound.

No argument here.

So you're agreeing with me but you still say I'm wrong :headscrat

Read the underlined words again. It is only a monopolar speaker that allows a fair degree(which is relative) of the mids to be heard around them is the key to that sentence. Since most monopolar speakers favor their forward radiation pattern from 15-20db over the rear ward one at middle and high frequencies, it is not likely you will find a monopolar speaker with any significant audible (also relative) output radiating backwards.

I agree with your qualifier, but not your original statement without it.

 

[RickeyM]

So how do you account for the people who've stated that their sound improved by pulling the speakers away from the front wall. Shouldn't it make them sound worse by putting them closer to those reflecting points on the side walls, ceiling and rear wall.

By moving a speaker away from the front wall, bass frequencies are not reinforced as efficiently as they would if they were very close to the front wall. Keep in mind, the corners have the loudest resonances in rooms. The further you move them away from there, the less efficient those resonances are stimulated.

That doesn't answer the question. The sound improvements noted are much more than a reduction of boundary reinforced bass.

I use 2 acoustic absorption panels (mid to upper frequencies) on the wall between my speakers - they absolutely DO make a difference and it's readily apparent to anyone who listens with/without. First-person observation, not text-book explanation although I'm sure the text-book explains this if you look beyond 'direct' effect and consider the whole room which in my opinion you have to do - it's a system.

Those two panels between your speakers are absorbing mid high frequency reflections coming from other surfaces towards them. Unless your speakers are omni-directional at all frequencies, they are not mean't to absorb what is coming from the speaker at those frequencies.

The first reflections are usually from the floor right in front of the speakers. The engages the ceiling as those reflections bounce around until they become inaudible. Based on the dispersion pattern of the speakers, axial, tangential and oblique reflections also occur.

Let's see, those panels Billfort uses are absorbing sound that has bounced around until it's become inaudible? To be fair, in Billforts case, the panels may be "behind" the speakers relative to the listeners position, much of them is actually in front of the plane of the front of the speakers.
Then again, every room and setup is different right?

 

[Sir Terrence]

That doesn't answer the question. The sound improvements noted are much more than a reduction of boundary reinforced bass.

He asked me a specific question in this case, and I gave him a specific answer.

How do you know the improvement are more than a reduction of boudary reinforced bass? You would be very surprised how much a reduction in bass frequencies really helps the overall frequency response of the speakers in the room...hello bass traps!

Let's see, those panels Billfort uses are absorbing sound that has bounced around until it's become inaudible? To be fair, in Billforts case, the panels may be "behind" the speakers relative to the listeners position, much of them is actually in front of the plane of the front of the speakers.
Then again, every room and setup is different right?

Different setup, same goals. His goal is to reduce the amount of middle and high frequency information (bouncing) within the room. That can be achieved with panels behind the speakers, or panels on the side and rear walls as well.

 

[RickeyM]

He asked me a specific question in this case, and I gave him a specific answer.

That was me that asked a question and you still haven't answered it.

How do you know the improvement are more than a reduction of boundary reinforced bass? You would be very surprised how much a reduction in bass frequencies really helps the overall frequency response of the speakers in the room...hello bass traps!

Come on now, we both know the job of bass traps is to smooth out problematic peaks of a speaker's response in a given room not simply "a reduction in bass frequencies" as you put it.

We get that you did an RTA measurement behind some speakers and found that most (but not all) of what registered was low frequencies. Given the number of variables possible between speakers used and rooms, you gotta know that other combinations aren't going to measure the same.

After all, it was you who stated that the panels Billfort is using "are absorbing mid high frequency reflections coming from other surfaces toward them" when a quick look at the pic of his speakers, their placement and the placement of his absorber panels says differently. It's obvious that the first
"mid high frequencies" hitting those panels are coming right off the speakers.

 

[klama2006]

Yea, speakers are weird. They can all be placed in a optimum position, and I've found it"s usually not where they look the best.


The solution is to mark the best sounding spot , and allow for there removal back towards the wall, Just push them back against the wall for the rest of the family, and pull them into proper position when you got the place to yourself.

 

[Peter Walker]

Yea, speakers are weird. They can all be placed in a optimum position, and I've found it"s usually not where they look the best.


The solution is to mark the best sounding spot , and allow for there removal back towards the wall, Just push them back against the wall for the rest of the family, and pull them into proper position when you got the place to yourself.

Sadly my speakers didn't come with a forklift ! ! ! :yes::yes::sigh::yes::tears:

 

[Sir Terrence]

That was me that asked a question and you still haven't answered it.

The answer is there, and I am sorry you can't see it.

Come on now, we both know the job of bass traps is to smooth out problematic peaks of a speaker's response in a given room not simply "a reduction in bass frequencies" as you put it.

When you smoothen out a peak, you ARE reducing the amount of bass energy in the room. Where does the output of the peak go once it is smoothened out? It is absorbed by the bass trap. Since bass traps do not operate like a parametric EQ, it will also absorb the energy that is around the peak as well.

We get that you did an RTA measurement behind some speakers and found that most (but not all) of what registered was low frequencies. Given the number of variables possible between speakers used and rooms, you gotta know that other combinations aren't going to measure the same.

I already stated that Ribbons and electrostatic planars have a figure 8 dispersion pattern, and do not become more directional as frequencies increase like monopolar speakers do.

After all, it was you who stated that the panels Billfort is using "are absorbing mid high frequency reflections coming from other surfaces toward them" when a quick look at the pic of his speakers, their placement and the placement of his absorber panels says differently. It's obvious that the first
"mid high frequencies" hitting those panels are coming right off the speakers.

Oh really, did you measure this, or are you just guessing and making assumptions? The driver on his speakers radiates in a 90x40 degree pattern. Even with the inward tilt of the baffle, the width of that baffle combined with a 90 degree horizontal dispersion pattern of the driver itself, would not lend to much midrange or high frequency information leaking around the cabinet and interacting with the front wall. His speaker is a monopolar speakers, and as such it output just like any other monopolar speaker becomes more directional as the frequencies increase.

 

[Jon_Logan]

um.... ....while it's true that dipole speakers have a figure 8 pattern at some (lower) frequencies, it is untrue that dipole, or bipole do not become more directional as the frequency increases.

 

[RickeyM]

Quote:
Originally Posted by RickeyM
"That was me that asked a question and you still haven't answered it."

The answer is there, and I am sorry you can't see it.

Quote:
Originally Posted by RickeyM
"Come on now, we both know the job of bass traps is to smooth out problematic peaks of a speaker's response in a given room not simply "a reduction in bass frequencies" as you put it."


When you smoothen out a peak, you ARE reducing the amount of bass energy in the room. Where does the output of the peak go once it is smoothened out? It is absorbed by the bass trap. Since bass traps do not operate like a parametric EQ, it will also absorb the energy that is around the peak as well.



I already stated that Ribbons and electrostatic planars have a figure 8 dispersion pattern, and do not become more directional as frequencies increase like monopolar speakers do.

Quote:
Originally Posted by RickeyM
"After all, it was you who stated that the panels Billfort is using "are absorbing mid high frequency reflections coming from other surfaces toward them" when a quick look at the pic of his speakers, their placement and the placement of his absorber panels says differently. It's obvious that the first
"mid high frequencies" hitting those panels are coming right off the speakers."


Oh really, did you measure this, or are you just guessing and making assumptions? The driver on his speakers radiates in a 90x40 degree pattern. Even with the inward tilt of the baffle, the width of that baffle combined with a 90 degree horizontal dispersion pattern of the driver itself, would not lend to much midrange or high frequency information leaking around the cabinet and interacting with the front wall. His speaker is a monopolar speakers, and as such it output just like any other monopolar speaker becomes more directional as the frequencies increase.

SirT you're doing such a good job of not answereing questions that i'm not going to bother with asking any more of them. Oh, you've typed a lot of words that on first glance seem like answers, but they really aren't. I think I'll go do something productive like tinkering with the placement of some panels on my front wall. Behind the speakers :thmbsp:

 

[RickeyM]

Back to our regularly scheduled programming...

Getting back to the original point of this post...

What I'm asking about in this post is if having a minimal amount of gear next to the speaker sides is OK or not, or if striving for absolutely NOTHING between speakers is the goal.

I don't think there is a definite "APPLIES TO ALL CASES" rule here. Speaker sizes and types vary, as do speaker distances (to wall, to the other speaker), angles and such. As you said "I still have to live in, and move around in, this new room." so you still have to balance "ideal" with "practical".