Anyone tried stacked Stages for Center Channel

babydoc · Jul 2, 2010

I was intrigued by a recent thread on CC's for the larger MLs, Odyssey, Summits, CLX's. I am currently using a single stage between my CLX's. Would be interested if anyone has gone that route to get a larger suface area more in line with that the two front channels.

JayJayHache · Jul 3, 2010

...am also very interested to learn of peoples experiences.

Getting an amp to drive them would require wiring them up in a sensible fashion and ideally require an even number of Stages - 4 units can be wired to give an identical load impedance as 1 Stage - but with 4 times the power handling

JayJayHache

zaphod · Jul 4, 2010

i'd split the feed before the amp and use two amps.

JayJayHache · Jul 5, 2010

zaphod said:
i'd split the feed before the amp and use two amps.

Why? (Unless the amp is underpowered...)

JonFo · Jul 5, 2010

I'd do the following:

Get a DBX-4800 speaker processor, feed the center channel input to it, then configure a 5-way split of the source signal and route each to its own output chain, where delays (to compensate for positional variances), EQ (to 'shade' the outer tweeters) and gain (again, to shade the outer units) can be applied.

Feed each of the five output signals to the inputs of a Sunfire TGA-5200 multichannel amp, then drive each of the Stages off one of those channels.

Using a measurement setup, fine tune delays and eq to get the stack to coalesce and have ideal line-source projection.

With no mods required, this should be fairly doable by anyone willing to tune the speaker processor processor using measurements.

This will give you a 5' linesource with 1,000w of power.

The one thing I'm not 100% sold on are the lobbing characteristics that twin stacks of mid-bass drivers would yield. But that's another topic.

robertawillisjr · Jul 5, 2010

What about Audyssey? Just a thought as I have no experience in this area.

zaphod · Jul 5, 2010

JayJayHache said:
Why? (Unless the amp is underpowered...)

to address the concerns in the posts before mine about the amp handling the load...

JayJayHache · Jul 7, 2010

JonFo said:
I'd do the following:

Get a DBX-4800 speaker processor.....

Jonfo can I please ask: why the need to process the signal for the drivers this way? If you look at an ML prodigy for example the entire enormous column is driven identically - so why process the signal heading to a virtual column which is faking a tall column?

Hope you don't mind me asking but I know you're a Guru in this area and would appreciate the insight...

gordonmenninger · Jul 7, 2010

JonFo said:
I'd do the following:

Get a DBX-4800 speaker processor, feed the center channel input to it, then configure a 5-way split of the source signal and route each to its own output chain, where delays (to compensate for positional variances), EQ (to 'shade' the outer tweeters) and gain (again, to shade the outer units) can be applied.

Feed each of the five output signals to the inputs of a Sunfire TGA-5200 multichannel amp, then drive each of the Stages off one of those channels.

Using a measurement setup, fine tune delays and eq to get the stack to coalesce and have ideal line-source projection.

With no mods required, this should be fairly doable by anyone willing to tune the speaker processor processor using measurements.

This will give you a 5' linesource with 1,000w of power.

The one thing I'm not 100% sold on are the lobbing characteristics that twin stacks of mid-bass drivers would yield. But that's another topic.

Jon, are you aware that the DBX unit cost over $4,000? That seems a bit pricey considering the price of the Stage... Nice idea, but just sayin...

JMAUSGP · Jul 7, 2010

JonFo,

What about the chances of doing this with three Stages instead of 5? With just 3 would there be any less tweaking since the speakers are closer together?

robertawillisjr · Jul 8, 2010

gordonmenninger said:
Jon, are you aware that the DBX unit cost over $4,000? That seems a bit pricey considering the price of the Stage... Nice idea, but just sayin...

Yeah, but you would want to do it right. There may be less expensive options but you need something to equalize the speakers as far as interaction and the time domain issue. Jon has it right.

JayJayHache · Jul 9, 2010

robertawillisjr said:
...you need something to equalize the speakers as far as interaction and the time domain issue

So if you have a column made up of Stages driven identically wouldn't the entire column move identically? Just like a single large column speaker?

Can anybody tell me why a column of Stage speakers need time alignment whereas a single column speaker in exactly the same place doesn't ?

I'm not sure where the problem is coming from BUT i'm also fairly sure that using multiple centre speakers is problematic unless done 'right' -

robertawillisjr · Jul 9, 2010

JayJayHache said:
So if you have a column made up of Stages driven identically wouldn't the entire column move identically? Just like a single large column speaker?

Can anybody tell me why a column of Stage speakers need time alignment whereas a single column speaker in exactly the same place doesn't ?

I'm not sure where the problem is coming from BUT i'm also fairly sure that using multiple centre speakers is problematic unless done 'right' -

Well tall single column speakers are designed to put all of the sound at a location at the same time (don't ask me how). When you stack the Stages you have to do the design and implementation yourself. Also although the Stages are the same make, they are different speakers and have some variations. So (INMHO) an optimal installation will need some equalization to integrate all of these slightly different speakers into one speaker.

Now, you can just stack the speakers and connect them to an amplifier (keeping the impedance problem in mind) and listen carefully. If you are satisfied (and don't blow the amp), then fine. I am not trying to be sarcastic or anything. I am just mindful that the proof is always in the listening.

JRace · Jul 9, 2010

JayJayHache said:
So if you have a column made up of Stages driven identically wouldn't the entire column move identically? Just like a single large column speaker?

Can anybody tell me why a column of Stage speakers need time alignment whereas a single column speaker in exactly the same place doesn't ?

I'm not sure where the problem is coming from BUT i'm also fairly sure that using multiple centre speakers is problematic unless done 'right' -

A line-array (identical stacked drivers) will have a comlicated crossover that will alter the signal arriving at each driver. It is much more complicated than just stacking the drivers and powering them.

JRace · Jul 9, 2010

robertawillisjr said:
Now, you can just stack the speakers and connect them to an amplifier (keeping the impedance problem in mind) and listen carefully. If you are satisfied (and don't blow the amp), then fine. I am not trying to be sarcastic or anything. I am just mindful that the proof is always in the listening.

Not to be a jack-ass or anything...but would you know what to listen for?
In other words, how would you know it is working right or wrong?

When it comes to this audio game, you sometimes have no idea just how wrong it is until you hear it done right.

JayJayHache · Jul 10, 2010

JRace said:
Not to be a jack-ass or anything...but would you know what to listen for?

That's a good question - I'd answer it like this:

I know that a small single CC sounds 'Wrong' as it's not mating properly with large ML Fronts - sound panning from Left to right suffers through the centre and gets that 'Small speaker' sound. High frequencies suffer especially with the 'vertical' column of sound being too short - noticeable if you enjoy listening sitting and standing.

I'd consider the stack to sound 'Right' as long as it mated perfectly with the other 2 fronts - and allowed me to enjoy the music 100% seamlessly when sitting or standing

The easiest test would be to have a stereo pair set up for testing - with the Left speaker the normal Front-Left ML speaker (in my case a prodigy) - and the Right the new 'Stack' of ML Centres - if we got that sounding like a matched pair then we have a winner!

JayJayHache · Jul 10, 2010

JRace said:
A line-array (identical stacked drivers) will have a comlicated crossover that will alter the signal arriving at each driver. It is much more complicated than just stacking the drivers and powering them.

Not to be pedantic or anything as I'm 100% genuinely interested in this and appreciate your insight - however ML's own flagships (Statements E2 / E2x) use a column of identical drivers without altering the signals for each.

Something is missing in my (our?) understanding of this phenominon - if we were trying to focus the sound from a stack of speakers then you are 100% correct (ie if the column was curved to that each CC pointed at the listeners ear level - but that's not what i'm investigating...

If you are trying to build a true vertical column then altering the timing to each driver seems wrong to me...

robertawillisjr · Jul 10, 2010

JayJayHache said:
Not to be pedantic or anything as I'm 100% genuinely interested in this and appreciate your insight - however ML's own flagships (Statements E2 / E2x) use a column of identical drivers without altering the signals for each.

If you are trying to build a true vertical column then altering the timing to each driver seems wrong to me...

I just looked at the Statement manual and brochure. I can't say whether you are correct or not. The column of drivers are the bass modules not mid and high range. Which may or may not make a difference.

Keep in mind that your speakers are not identical, they are the same model.

Well the easy thing is to just do it and see if the setup sounds "wrong". I've tried similar experiments and it took some doing to get the sound "right".

Try it and let us know what you think.

JonFo · Jul 11, 2010

JayJayHache said:
Jonfo can I please ask: why the need to process the signal for the drivers this way? If you look at an ML prodigy for example the entire enormous column is driven identically - so why process the signal heading to a virtual column which is faking a tall column?

Hope you don't mind me asking but I know you're a Guru in this area and would appreciate the insight...

For more detail on the ‘why’ and a good bit of ‘how’, please read this white paper on line array theory and design. It’s written in a very accessible manner by an expert in the field.

Line array white paper: http://www.audioroundtable.com/misc/nflawp.pdf

If you look at Table I in the doc, you see several references to power tapering as a means of mitigating some of the side effects of stacked discrete circular drivers (the 5 tweeters of the 5 stages in the case).

One challenge a stack of Stages presents is the tweeter to tweeter separation is large relative to the frequencies it covers, so one strategy might be to roll-off (or even disconnect) the tweeters on the outer 4 units, leaving only one point-source tweeter from the middle unit.

The other, as I noted earlier is lobbing from the widely separated mid-bass units. But then, the lobbing is inherent in that design anyway.

JonFo · Jul 11, 2010

gordonmenninger said:
Jon, are you aware that the DBX unit cost over $4,000? That seems a bit pricey considering the price of the Stage... Nice idea, but just sayin...

Quite aware, I own one

I guess one could use a DriveRack 260 instead, as it supports a 1x5 setup. Used ones are ~$500.

But don't think for a minute that one can solve the 'high performance center' problem for much under $6K to $7K.

Anyone tried stacked Stages for Center Channel

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