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Old 20th January 2013, 03:40 PM   #31
Pnotus is offline Pnotus  Sweden
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Hello Owen!

Oops! My mistake - of course itīs the TG9 I'm refering to.
It's very possible that the earlier breakups give the impression of more and better extended treble.
I haven't measured anything yet. As of now I'm 1500 kms away from home and will be for a while.

My impressions are very subjective so they may not be for everyone. Deal breaker for me was that everything through the TG9 sounded more alive and really, in lack of better words for a 3,5", more dynamic. But i have had problems with polyprops before and understans that this may be personal taste more than quality preference.

Regarding your use of the TC9. I'm sure you are right on spot with these and their measurements, I mean absolutely no disregard for your knowledge or choice.
Knowing that english is not native to me I realis(z?)e that my posts can come off as a bit plump.

/Pontus
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Old 20th January 2013, 07:29 PM   #32
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Thanx Owen, I've seen your thread and it was partly the inspiration for this project. The only drawback for me is that I can't/won't be using a digital crossover or eQ, everything has to be done passively through the crossover. My in-wall rack is completely full so there's no option to add anything. Speaker wiring is in wall as well with two pairs per side on either side of the screen. One set reserved for the top end, the other for passive bass bins that already are in place. If you have any insights on doing this all passively, I'm all ears.

After back and forth with Scott, and reviewing the performance of the TC6, my mindset is now a central line of 16 TC6s flanked on either side by 12 TC9s for a driver total 40 drive units per speaker. With this close spacing, I think I can cross as low as 800hz or 1.6khz second order. To combat HF losses above 10khz from comb filtering in the tweeter line, I'm wondering if a 1st order on the midwoofers and 2nd order on the tweeters isn't the better way to go, slightly tilting the response upwards.
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Old 20th January 2013, 07:30 PM   #33
ScottG is offline ScottG  United States
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Quote:
Originally Posted by mayhem13 View Post
Honestly Scott, I don't need extension below 100hz, but nor do I want to sacrifice midbass 'slam' in the 100-150hz range either. I'll have to sim the TC9s a bit more and see what comes out.

Now I assume that combing from the tweeter array will exist above 8khz, but I'm guessing its effects won't be audible from my listening distance?
You won't really get "slam", or even "punch" for that matter, from any low mass domestic line array. (..well, not without serious "boost" anyway.) BUT, with a crossover around 150 Hz you get that from the "sub".

At a 14 foot distance with a multiplicity of reflections from walls and furnishings - I think it's *highly unlikely* that combing will be audible. Even if it is, I think it's even less likely that it would be objectionable.
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Old 20th January 2013, 07:59 PM   #34
ScottG is offline ScottG  United States
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Quote:
Originally Posted by mayhem13 View Post
..my mindset is now a central line of 16 TC6s flanked on either side by 12 TC9s for a driver total 40 drive units per speaker. With this close spacing, I think I can cross as low as 800hz or 1.6khz second order.

To combat HF losses above 10khz from comb filtering in the tweeter line..

-a "flanking" arrangement is a bad idea UNLESS it's a ".5" baffle-step loss addition at a much lower freq.. (300 Hz crossover or lower for the low-pass on the .5 array.) (..I've tried this myself - the higher in freq. the weirder the combing and dispersion pattern, and the further away you have to get from the speakers to get any sort of integration window. Further away than 14 feet in my experience.)


Actually combing with small drivers doesn't work out as a pressure loss per se, rather very narrow band losses followed by narrow band gains - sort of a spiky/hashy behavior. As it get's higher in freq. the hash becomes less "narrow" which could leave you with a minor "dip", but with the Vifa 2" drivers I don't think it will be significant enough to need any correction.

What you will get however, is a lot of acoustic and diffraction gain at the lower end of the driver's response with the more drivers you use. Basically it "tilts" the freq. response downward as freq.s rise. Here is an example with somewhat different 2" drivers (..and note that the raw top-end response of these drivers is naturally "hashy" to begin with):

Parts Express: Project Showcase

What this means is that if the driver is naturally 86 db at the top of its range, AFTER it's been corrected passively it's still going to be 86 db unless there is voltage gain from a reduction in impedance (..and an amp that responds accordingly). In the design above the author just used a graphic equalizer to actively boost the top end.
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Last edited by ScottG; 20th January 2013 at 08:22 PM.
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Old 20th January 2013, 08:06 PM   #35
opc is offline opc  Canada
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Quote:
Originally Posted by Pnotus View Post
Hello Owen!

Oops! My mistake - of course itīs the TG9 I'm refering to.
It's very possible that the earlier breakups give the impression of more and better extended treble.
I haven't measured anything yet. As of now I'm 1500 kms away from home and will be for a while.

My impressions are very subjective so they may not be for everyone. Deal breaker for me was that everything through the TG9 sounded more alive and really, in lack of better words for a 3,5", more dynamic. But i have had problems with polyprops before and understans that this may be personal taste more than quality preference.

Regarding your use of the TC9. I'm sure you are right on spot with these and their measurements, I mean absolutely no disregard for your knowledge or choice.
Knowing that english is not native to me I realis(z?)e that my posts can come off as a bit plump.

/Pontus
Hi Pontus,

Not at all... I actually re-read my post and it was me who came off a little edgy

Certainly, the cone breakup could give an impression of more HF output, and possibly even more detail, but I personally would opt for the softer and more controlled breakup of the paper cone.

Again, the sonic preference is always going to come down to taste, and personal preference. We're certainly allowed to differ in our opinions when it comes to personal preference

Quote:
Originally Posted by mayhem13 View Post
After back and forth with Scott, and reviewing the performance of the TC6, my mindset is now a central line of 16 TC6s flanked on either side by 12 TC9s for a driver total 40 drive units per speaker. With this close spacing, I think I can cross as low as 800hz or 1.6khz second order. To combat HF losses above 10khz from comb filtering in the tweeter line, I'm wondering if a 1st order on the midwoofers and 2nd order on the tweeters isn't the better way to go, slightly tilting the response upwards.
mayhem13:

Just out of curiosity, why not do away with the TC9 drivers all together and just stick with a single line of the TC6?

Since you're using a sub to fill in the low end, there isn't really a need for anything larger than the TC6, and you'll get a cleaner HF response with none of the headaches of trying to implement a passive filter between two arrays.

If you make the line sufficiently long, you'll get a naturally boosted bottom end that will easily make it down to 125-150Hz even with just the TC6.

I can promise you it will sound better using a single full-range driver than trying to cross over between two arrays.

If you needed the LF extension, and were planning to run without a sub then the little 2" Vifa drivers would not be sufficient, but I think you'll find that with a sub, they will be more than enough all on their own.

How high is your ceiling?

Cheers,
Owen
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Old 20th January 2013, 10:48 PM   #36
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Ceiling is 8ft, bass bin enclosures are 24" tall......figuring a 48" line would be ideal with equal distance from the floor and ceiling to the tops and bottoms of the lines.

Funny....been wondering why just not use the TC 6's alone either. I can get my bass bins up to 240hz cleanly and a third order low pass.
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Old 20th January 2013, 11:04 PM   #37
opc is offline opc  Canada
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Quote:
Originally Posted by mayhem13 View Post
Ceiling is 8ft, bass bin enclosures are 24" tall......figuring a 48" line would be ideal with equal distance from the floor and ceiling to the tops and bottoms of the lines.

Funny....been wondering why just not use the TC 6's alone either. I can get my bass bins up to 240hz cleanly and a third order low pass.
If that's the case, I'd certainly go with just the TC6 drivers in a single line. Having that much flexibility with your subs means you'll definitely be able to integrate the two cleanly.

As for line length, I would make them taller if anything, but I'd be curious to hear Scott's input on this. I'm guessing a taller line with roughly 80" of actual drivers would be pretty much perfect for 8' ceilings. With a line that length you'll be loading the room in an ideal manner, and you'll have enough natural LF boost to help compensate for baffle step. More drivers also means less work from each driver which will improve distortion and increase efficiency. Based on my experience with the TC9 drivers, I'd be willing to bet a line like that would require little or no EQ as long as you get the baffle width right, and cross over to a sub somewhere between 100 and 200Hz.

The only downside I can see is that the driver already has a bit of an inherent tilt downwards from LF to HF. This might mean the end result will need a little bit of boost in the top end, or if you're using passive crossovers, you'll need to attenuate the lower midband.

Cheers,
Owen
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Old 20th January 2013, 11:54 PM   #38
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I actually need to mount these on top of the sub/bins......inboard is prevented by the projection screen and outboard too close to the side walls. I could certainly increase the line length, but 60" would be max. My thinking would be the line biased towards one boundary over the other created problems in the vertical dispersion.....and some unintended bounce.

As for baffle width...it can be as wide as 12" if needed to combat baffle step losses.
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Old 21st January 2013, 04:02 AM   #39
ScottG is offline ScottG  United States
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Quote:
Originally Posted by mayhem13 View Post

Funny....been wondering why just not use the TC 6's alone either. I can get my bass bins up to 240hz cleanly and a third order low pass.
If you make the line long enough, why not?

It also depends on the length to the near boundaries - i.e. floor and ceiling (..page 9 of the Line Array paper).
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Last edited by ScottG; 21st January 2013 at 04:09 AM.
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Old 21st January 2013, 10:38 AM   #40
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ScottG and others,

The symmetrical (or flanking) style line array (a tweeter line with a line of mids on each side of the tweets) has been used to advantage for several line array speakers manufactured by McIntosh Labs. Robert E. Green (see his regonaudio site) did a review of their XRT28 a few years ago in 'The Absolute Sound' and later wrote a supplemental paper on the in-room advantages of the flanking style array as you can see at:

How to Tell How a Speaker Sounds in a Room: (Supplement to REG's review of the McIntosh XRT28s)

You can think of the XRT28 array as elemental MTMs placed horizontal and stacked to create the flanking (or symmetrical) line array. If you can achieve close spacing, you can essentially direct the nulls that you get with a horizontal MTM so that side wall reflections are minimized as pointed out by Green. Thus you get the reduction in floor and ceiling reflections that you normally observe with a line array plus another degree of freedom to minimize sidewall bounce.

McIntosh has taken this concept to a new level in their current XRT2K model which you can see on the McIntosh web site. Follow the support tab to select 'speakers' and enter XRT2K to download the brochure for this model. That is a mind blowing line array configuration!

All that being said about the possible advantages of a symmetrical array, I expect that a single line array of wide range drivers supported with woofers to cover the low bass and into the lower midrange may suffice for the original poster.

Jim

Last edited by Jim Griffin; 21st January 2013 at 10:49 AM. Reason: correction
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