Cedar Creek Cinema

**Sonnie** · **07-31-09, 09:40 AM**

My build threads are in my sig links... those are the only links I have. Very very time consuming to say the least, but rewarding too.

**Andysu** · **08-06-09, 10:25 AM**

Quote:

Sonnie wrote:

My build threads are in my sig links... those are the only links I have. Very very time consuming to say the least, but rewarding too.

So it is and I wouldn’t have even guessed that.

I like the look of it and the teeth rattling well I get that each time I travel on Bournemouth buses lots of low end bass vibrating all for a £3.00 all day ticket.

**Wayne A. Pflughaupt** · **08-07-09, 02:35 PM**

Just curious, Sonnie, how does the "EQ all the subs as one" thing work as far as linear response (or a reasonable facsimile thereof) at the various seats?

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We are extremely pleased with everything, despite running into several hurdles along the way and it taking what seems like forever to get it all done.

Ultimately, it paid off with what we really wanted after we teased ourselves with the first HT room we built. I am not sure we could do anything any different or make any changes that could make us any happier with the end result. It sounds awesome and meets or exceeds our every expectation.

What's all this "we" business? Does Angie actually come out to this one with you?

Regards,
Wayne

**brucek** · **08-07-09, 03:30 PM**

Quote:

how does the "EQ all the subs as one" thing work

I've wondered this myself.

Scenario:

Sub #1 has an +8dB peak @50Hz at the listening position.
Sub #2 has an +8dB peak @50Hz at the listening position.
Total peak at listening position @50Hz is +16dB.
Sonnie applies a single -16dB cut and all is well.

Would it have been better to apply a more reasonable -8db cut @50 Hz to both subs?

brucek

**SteveCallas** · **08-08-09, 01:26 AM**

If sub 1 and sub 2 both have an 8db peak around 50hz, assuming no cancellations between them, the summed response would be an 8db peak around 50hz, not 16db.

**Wayne A. Pflughaupt** · **08-08-09, 01:55 AM**

Yeah, that's what I was thinking, too. All things being equal, the second sub merely increases gain, across the board.

Where's Sonnie?

Regards,
Wayne

**brucek** · **08-08-09, 08:39 AM**

Quote:

If sub 1 and sub 2 both have an 8db peak around 50hz, assuming no cancellations between them, the summed response would be an 8db peak around 50hz, not 16db

So, at the listening position, if sub #1 has a peak of +8dB @50Hz and sub #2 has a dip of -8dB @50Hz, is there not a cancellation?

Do acoustic signals not cancel and reinforce?

Is signal reinforcement not how we enjoy extra headroom by adding a second sub, allowing the volume of each to be reduced?

brucek

**Sonnie** · **08-08-09, 12:38 PM**

Sorry guys... Angie and I were on a road trip yesterday to pick up yet another set of speakers.

Wayne... the "we" stuff is mostly pointing to the design and finish of the room, however, Angie has spent more time in this room since it was built than she did all total in the other room. Still yet... "we" might as well be me and my imaginary friend.

I have tried the equalization for all the seats and I do not care for it. I do not know if it is psychological because I can see the huge differences in the measured responses or if I really notice a difference, but I do not like it.

I can equalize for the main listening position only... running three Audyssey measurements from that seat and from that seat it looks good. The other seats really do not look or sound any better or worse than they do when I use averaging and measure multiple seating locations... BUT at least I get one position, the main one, looking and sounding good.

As far as the eq'ing all subs as one... I do not know the technical aspects of it, but I do know it works regardless of the location of the subs. I also know that any time I have tried (and I have tried many times) to equalize two subs independently, that while the individual responses have looked very good, once they are combined, the overall response looks awful. It has never... and I emphatically repeat "NEVER!" worked when I have tried to equalize subs independently for an overall smooth combined response. Quite frankly, I do not recall anyone ever succeeding at doing so... and it does not make sense that it can be done either.

Quote:

brucek wrote:

So, at the listening position, if sub #1 has a peak of +8dB @50Hz and sub #2 has a dip of -8dB @50Hz, is there not a cancellation?

Do acoustic signals not cancel and reinforce?

Is signal reinforcement not how we enjoy extra headroom by adding a second sub, allowing the volume of each to be reduced?

brucek

In this situation you are measuring the independent responses to see the peak and dip. I believe if you measured them together that your response would be flat at 50Hz and there would be any need of eq'ing. However, trying to equalize them independently, you will apply two unnecessary filters.

**SteveCallas** · **08-08-09, 04:06 PM**

Quote:

brucek wrote:

So, at the listening position, if sub #1 has a peak of +8dB @50Hz and sub #2 has a dip of -8dB @50Hz, is there not a cancellation?

Do acoustic signals not cancel and reinforce?

Is signal reinforcement not how we enjoy extra headroom by adding a second sub, allowing the volume of each to be reduced?

Yes, they cancel and reinforce each other. Regarding reinforcement, the most that can be gained by doubling displacement is 6db, and that's if everything is perfect. If both subs have roughly the same FR - even if that means a 35db peak around 50hz - the combined FR will stay the same (assuming no new room effects from the position of the second sub), it will just be increased 0-6db across the entire range.

If one sub is +8db at 50hz and the other -8db at 50hz, then yes, assuming no new room effects from placement of the second sub, they would cancel each other out and you would be flat at 50hz. The magnitude of the "flat" FR at 50hz would still be 0-6db higher though.

**brucek** · **08-08-09, 04:45 PM**

Quote:

the combined FR will stay the same (assuming no new room effects from the position of the second sub), it will just be increased 0-6db across the entire range.

Not that this is my field, but is there a confusion here between absolute and relative levels.

As an example, if I introduce two +8dB filters at 50Hz into an equalizer, the result will be absolute +16dB at 50Hz.

That's a doubling of the single +8dB level, which is relative +6dB higher (20 log 16/8).

brucek

**SteveCallas** · **08-09-09, 12:13 AM**

The EQ will boost the input signal by 8db twice - that's different than taking two subs with the same FR and playing them at the same time.

**brucek** · **08-09-09, 11:09 AM**

Quote:

that's different than taking two subs with the same FR and playing them at the same time.

Yeah, that's true. See below.

Quote:

If sub 1 and sub 2 both have an 8db peak around 50hz, assuming no cancellations between them, the summed response would be an 8db peak around 50hz, not 16db.

I got thinking about this, and I must say I was thinking about filters when I said +8dBSPL + 8dBSPL =16dBSPL. That's not correct - my bad. When we add sound pressure you must use the logarithmic calculation. The total sound pressure level is not the algebraic sum of sound pressure levels. It would be as follows:

If I have two signals in a room playing at +75 dBSPL, then the resultant SPL level is +81.02 dBSPL (pressure result is double = +6.02dB higher).
Math is 20 log [10^(SPL1/20) + 10^(SPL2/20)].

And, if I have two signal peaks @50Hz in a room of +8 dBSPL, then the resultant peaks SPL level is +14.02 dBSPL (result is double = +6.02dB higher).
Math is the same 20 log [10^(SPL1/20) + 10^(SPL2/20)].

So both increase by 6dB.

brucek

**Wayne A. Pflughaupt** · **08-09-09, 05:47 PM**

Quote:

Sonnie wrote:

Sorry guys... Angie and I were on a road trip yesterday to pick up yet another set of speakers.

What?? More speakers?? Well, if I recall - from where you are, it’s a “road trip” to anywhere!

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As far as the eq'ing all subs as one... I do not know the technical aspects of it, but I do know it works regardless of the location of the subs. I also know that any time I have tried (and I have tried many times) to equalize two subs independently, that while the individual responses have looked very good, once they are combined, the overall response looks awful. It has never... and I emphatically repeat "NEVER!" worked when I have tried to equalize subs independently for an overall smooth combined response. Quite frankly, I do not recall anyone ever succeeding at doing so... and it does not make sense that it can be done either.

Understood, you EQ’d all the subs as one, presumably from the sweet spot. What I’m trying to find out is, does that technique also gets decent response at the other seats as well?

Regards,
Wayne

**rcarlton** · **08-09-09, 06:12 PM**

Sonnie,
Just read this thread. Sweet looking HT. Wow.

If I ever get to Alabama I need to stop by.

**brucek** · **08-09-09, 06:25 PM**

Quote:

Sweet looking HT. Wow.

Yeah, I'm still shaking my head in awe about those F1 Audio 18 towers with the port tuning in the stage..... I would have liked to see more detail in the "Rise of the Eighteens" thread. It seemed to go from concept to finished in a few posts without detail pics......

brucek

**Wayne A. Pflughaupt** · **08-09-09, 07:15 PM**

Quote:

brucek wrote:

Quote:

how does the "EQ all the subs as one" thing work

I've wondered this myself.

Scenario:

Sub #1 has an +8dB peak @50Hz at the listening position.
Sub #2 has an +8dB peak @50Hz at the listening position.
Total peak at listening position @50Hz is +16dB.
Sonnie applies a single -16dB cut and all is well.

Would it have been better to apply a more reasonable -8db cut @50 Hz to both subs?

Quote:

brucek wrote:

And, if I have two signal peaks @50Hz in a room of +8 dBSPL, then the resultant peaks SPL level is +14.02 dBSPL (result is double = +6.02dB higher).
Math is the same 20 log [10^(SPL1/20) + 10^(SPL2/20)].

Nothing like a "real live" experiment; maybe this will help clear things up. My DIY sub has two drivers, each powered by an independent amplifier channel. So, I can run both drivers together, or only one at a time. Does this meet the “all things being equal” requirement?

Ideal to the discussion, I have a honkin’ peak at ~42 Hz.

Here’s a graph I took today. The blue trace is both drivers running (no EQ). The red trace is one driver only. As you can see, the only thing that changes running both is overall gain. I suppose you could say the peak is “worse,” but its relation to the rest of the curve is the same.

Name: one vs. two subs.jpg
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Regards,
Wayne

**brucek** · **08-09-09, 08:13 PM**

Guess you're right - I'm not thinkin' today...........

Sorry for the hi-jack Sonnie...

**Wayne A. Pflughaupt** · **08-12-09, 09:19 PM**

So - how 'bout it, Sonnie?

Quote:

Wayne A. Pflughaupt wrote:

Quote:

As far as the eq'ing all subs as one... I do not know the technical aspects of it, but I do know it works regardless of the location of the subs. I also know that any time I have tried (and I have tried many times) to equalize two subs independently, that while the individual responses have looked very good, once they are combined, the overall response looks awful. It has never... and I emphatically repeat "NEVER!" worked when I have tried to equalize subs independently for an overall smooth combined response. Quite frankly, I do not recall anyone ever succeeding at doing so... and it does not make sense that it can be done either.

Understood, you EQ’d all the subs as one, presumably from the sweet spot. What I’m trying to find out is, does that technique also gets decent response at the other seats as well?

Regards,
Wayne

**Sonnie** · **08-13-09, 10:00 AM**

Quote:

brucek wrote:

Yeah, I'm still shaking my head in awe about those F1 Audio 18 towers with the port tuning in the stage..... I would have liked to see more detail in the "Rise of the Eighteens" thread. It seemed to go from concept to finished in a few posts without detail pics......

brucek

Well... sorry about that. You know how it can be sometimes when you have fifty-eleven things going on at one time. I did include pics of most of the framing though. I wish I had remembered to take more.

Quote:

Wayne A. Pflughaupt wrote:

Quote:

Understood, you EQ’d all the subs as one, presumably from the sweet spot. What I’m trying to find out is, does that technique also gets decent response at the other seats as well?

So - how 'bout it, Sonnie?

I know I answered this somewhere, just cannot figure out where, musta been in another thread. Anyway... the response from others seats is no better and no worse when equalizing from the main listening position than it is when equalizing from all positions. The only difference being that when you equalize from the main listening position, at least that one position is pretty much spot on... however, when you equalize from all positions, none are spot on. This may not work in every situation, but something tells me that it will probably be the case in most situations and it is what I would be recommending if I were writing the manufacturer manuals. They can say and write what they want, the the proof is in the measurements. Maybe sometime when I have extra hours available I will redo the entire comparison and save all the measurements. I probably have them saved, but I have so many, I am not sure I can decipher what is what.

Ahhh... and yes... more speakers. I swapped out my ML Spires for ML Prodigy's... I like the sound of the old style ML's better than I do the new style.

**Sonnie** · **08-20-09, 12:36 PM**

New pics...

**tonyvdb** · **08-20-09, 12:45 PM**

Sonnie, You never cease to amaze me. That is just the nicest theater setup I have seen

Now if only I had the money to get mine to look even half that good. My wife wants me to do something with it but it all takes so much cash to get it there.

**Sonnie** · **08-20-09, 12:52 PM**

Thanks Tony!

You know it's only money...

**SQCherokee** · **08-21-09, 11:06 PM**

are all those power indicators alittle distracting up front?

**Sonnie** · **08-22-09, 12:33 AM**

I don't even notice them. My eyes are always on the screen.

No one else has complained either, not that they would.

**Wayne A. Pflughaupt** · **08-22-09, 08:13 AM**

Quote:

Sonnie wrote:

Quote:

Wayne A. Pflughaupt wrote:

Understood, you EQ’d all the subs as one, presumably from the sweet spot. What I’m trying to find out is, does that technique also gets decent response at the other seats as well?

I know I answered this somewhere, just cannot figure out where, musta been in another thread. Anyway... the response from others seats is no better and no worse when equalizing from the main listening position than it is when equalizing from all positions. The only difference being that when you equalize from the main listening position, at least that one position is pretty much spot on...

So if I understand correctly, you’ve found that equalizing multiple subs as one from the sweet spot ends up being the same as equalizing a single sub from the sweet spot: You get the best response at the sweet spot but not necessarily at the other seats. I’d say that supports your “Just equalize them all as one” theory.

Another question, if you don’t mind: Some say that adding additional subs “evens out” response. Others say adding additional subs degrades response. Don’t recall if they meant at the sweet spot or for all the other seats as well, but which have you found to be the case?

Regards,
Wayne

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