So now, combing isnt a problem in an array?

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chrisb

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Joined 2002
amt said:
So was the equalization used in the 2005 article revealed? Ive got a pile of the NSBs and if a "decent" fullrange array can be built with them, Id like to do so. That 25hz response has me really intrigued.

Although I would expect larger drivers to provide higher quality bass performance, I already have the NSBs with a whopping $50 investment

amt
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The July 2006 AXP article on Roger's improved system probably more closely approximates the current commercial product. Using an entirely different driver ( unspecified OEM Vifa ) with, one would hope, substantially improved performance over the Pioneers , it of course required changes to EQ.

There's quite a bit of technical information and graphs published in the article, although the resolution could be better. The EQ graph shows a pair of fairly benign slopes, hinged slightly above the system resonance of 155Hz. "Compensation up to 20dB is used" although "equalization below 30HZ is reduced to prevent excessive infrasonic power from being delivered to the system"

He uses a MacIntosh MQ107, and gives detailed description of the settings and cap values used to tailor the response.


Scott: the article also mentions that the speakers are about 3" from the back wall, so boundary reinforcement definitely contributes to the in-room response. Hell, at only 7.5" wide, why not build them right into the stud cavities, and remove the baffle step variable altogether?
 
J

Jim Griffin

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Joined 2003
While we've got this line array thread going, I'd love to hear from Jim or someone else who's lived with a large LA speaker system about placement issues. Their unique dispersion pattern is what makes me wonder. I'd be using them in a living room situation and because of their large size I'd need to have them no more than three feet from the front wall (to the baffle). Two feet would be even better. Could I get away with this with a large array like the Alexandrite?
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My everyday listener line arrays use a sealed box for the woofers. I have them spaced 18-24" from the front wall. The sound is very nice in this small 12' x 15' downstairs listening room. Likely, a vented set of arrays might need another foot or so but I think you will be OK in your situation. Several of the Selah arrays can be produced with either sealed or vented bass alignment.

Jim
 
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chrisb

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Joined 2002
Chris8sirhC said:
As far as the equilization of the top end goes. In the far field, wouldnt that cause a rising frequency response if you eq it flat in the near field?
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If my limited understanding of Jim Griffin's white paper on N(ear) F(ield) LA 's is correct, the target listening area is well inside of the "critical" distance boundary - and with a full height (8ft) line, that boundary could well be outside the room.

His approach is quite different in several important respects from that of RR, most particularly in terms of multi-way drivers, and power tapering.
 
tomtt

tomtt

Member
Joined 2002
amt said:
So was the equalization used in the 2005 article revealed? Ive got a pile of the NSBs and if a "decent" fullrange array can be built with them, Id like to do so. That 25hz response has me really intrigued.

Although I would expect larger drivers to provide higher quality bass performance, I already have the NSBs with a whopping $50 investment

amt
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good at part layout ID?

a clue-



http://www.ids25.com/ids_equalizer.htm
 
J

Jim Griffin

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Joined 2003
IDS25 Equalizer

You can waste time trying to clone the The IDS25 equalizer but I suspect that any general equalizer will work for this function. Now it would be nice to have a 31 band EQ to be able to tweak more than just for the tweeter and woofer roll offs. EQ are available new and used for not much money. A Behringer DEQ2496 at $300 new would be the bomb for this case.
 
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Peter M.

Member
Joined 2005
SY said:


Only if you define "a driver's dispersion" as being the dispersion one would get if the driver were separated from the other elements. The array dispersion is a different matter, more relevant, and I'm trying to understand that better.

As you might guess, I have a selfish reason for my interest in understanding this...
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SY, I think it will function as one unit. If you look at ESL`s, often they have foam strips attached across the width. Does this cause comb filtering?

http://www.us.martinlogan.com/display_speaker/summit.html


Regards,
Peter
 
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Jim Griffin

Member
Joined 2003
I believe the speakers in the IDS-25 were designed by Vifa and are sold by Peerless as: Type Number: TG9FD-10-04.
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Dave,

Not the TG9FD-10-04 but the 8 ohms version which is the TG9FD-10-08 on the end. the IDS25 is an 8 ohms speaker which has 5 series wired drivers in 5 paralleled groups. Do that with the 04 version and you would get 4 ohms overall impedance. Do it with the 08 version and you get 8 ohms impedance.

If you had read this thread and previous , you would have seen my post #66 back on August 31st with the correct information and references to the Tymphany site for pdf. The IDS25 write-up doesn't talk to a shielded version but Vifa also offered an SD version instead of the FD version.

Jim
 
D

dfklink

Member
Joined 2006
Jim,

You're right of course, 8 ohms drivers are used. However, according to the Tymphany web site the 8 ohm version is discontinued. Ref:
http://www.tymphany.com/resource_library_archives.php?br=vf

In his aX article Roger does state "[the speaker] has an external steel cover, which reduces stray magnetic fields...} so I would guess he did use the "S" version, TG9FSD10-08. Also, Mat in posting #87 above confirms this.
Sorry I somehow missed your posting #66 above - this is a rather long thread (but a good one).

I attended the Rocky Mountain Audio Fest a couple weekends ago, all three days in fact (OK, so I need to get a life), and returned to listen to the IDS-25's each day. I was very impressed. I'm 63 and have some Tinnitus, and those small hotel rooms are not optimum listening environments, but no combing effects bothered me. The only other speaker I heard at the show that I would rather have was the MBL 101E's, but I sure can't afford $45,000 for a pair, and who can DIY those!

Thanks Jim, I (we) very much appreciate your insights.

Dave
 
J

Jim Griffin

Member
Joined 2003
DIY Version of IDS25

Dave,

I've been in contact with a gentleman in your area who plans to build a DIY version of the IDS25. He will be using Hi Vi B3S drivers (about $10 each retail) and likely a Behringer DEQ2496 equalizer. Should be a nice project for him.

All of the Vifa TG drivers are on the endangered list or at least in the discontinued obsolete bin. Tymphany scrubbed the offerings between the Vifa, Peerless, and Scan Speak lines when they took over. Only the Scan Speak drivers are all Danish made at this point with many of the other models produced in China. I suspect that you if you are an OEM you can order a batch of several hundred drivers of your choice from Tymphany.

Jim
 
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