Joe's "I'm never happy"-question-laden-DIY-speaker-thread. (1 Viewer)

[Joe Hsu]

So, now that the sub's back in working form, and hopefully will stay in such, I had a few nagging questions that I wanted to ask the good people of HTF:

A.) w/o an SPL meter, should I be able to hear audible differences in the sub's output while changing the phase? (PE 250W plate amp). I have a new layout down here, so I wanted to test that out. If so, foobar (mp3 player/app) can generate test tones really easily...what frequency shoudl the test tone be?

B.) Line arrays...I'm really loving the looks of some LAs I've seen, from the recent DIY event to the Stryke LA. What are the general aural differences between an LA and normal speaker? I'm currently running Studio 40s if you want to reference it to something. I've heard that they're less "direct", in that you can't pinpoint the source, unlike a normal point-source speaker like mine.
I'm considering selling my studio 40s in the future (I've only had them a few months, heh), and building speakers...if I go with LAs, say with the TangBand W3-871S, is there a minimum of drivers per speaker that I should use? I've seen them using 9, 13...and I love teh look of that G3 ribbon, but w/o hearing it, it's hard to justify $300 EACH on a blind buy, so I'd probably stick with a traditional tweeter. On an LA, is the speaker harder to drive? What's the frequency response like, and whatnot?

Thanks all for indulging me...my concerns with DIY have ramped up considerably in the last few months since I found out that one of my sister's friend's dad has a full-blown woodshop in his garage, and would be willing to let me use it/help me out...so I have all the tools and assistance I'd need, I'm just missing information and designs. I've been interested in another pair of bookshelves since I don't know if I'll be moving in the near future or not (it's possible), so that's one reason why an LA might not work...I thought the Criterion speakers looked impressive.

Alright, shutting up, I realize that this is a huge post, sorry

 

[Geno]

Joe, - buy a SPL meter - especially if you are calibrating your sub. Our ears can barely hear 20Hz but subs nowadays can go much lower. plus its easier on your ears too.

 

[ThomasW]

Line sources in general have a wider/deeper but slightly less focused soundfield.

Line sources also have much less distortion than point sources. This is fundamentally due to the work load being divided up between so many drivers.

IMO many LA noobies are over impressed with the performance of LA's using low buck drivers. This amazement is a primarily function of the different soundstage and low distortion, not necessarily 'better/more accurate' reproduction.

A LA made with a ton of cheap drivers isn't necessarily 'better' than a point source system made with higher quality drivers. As is always true one gets what one pays for......

A number of people are writing rave reviews on some of the more popular DIY arrays. An source (who will remain nameless) told me that it's pretty obvious that there are significant design flaws with some the designs he's heard and that people simply aren't hearing, can't hear, or are choosing to ignore these problems.... So caveat emptor!

A couple of other facts. To work best LA's need a pretty good sized room, otherwise they're just huge headphones. The taller the array the better. The 'best' arrays are literally floor to ceiling in height.... Finally properly integrating a line array of point source dynamic drivers with a line array = planar/ribbon/leaf tweeters is very, very difficult.

 

[Joe Hsu]

huh, thanks for the plethora of knowledge, Thomas.

Anybody else have something to say?

 

[Brett DiMichele]

Thomas,

Would that Source be Greg M. by any chance?????

Just guessing...

Of course an LA built with affordable drivers won't have as
stellar results as one built with much more costly, better
drivers. But who can afford 24 Seas Excels or something
along those lines? This is about Affordable solutions and
a Line Sourse using the best speakers no cost barred would
just be WAY too pricey for most of us.

I think a LA with modest drivers will perform much better
than your typical DIY Point Sources with "modest" drivers..

And some charecteristics of cheaper drivers can be ironed
out in the XO design but of course nothing can circumvent
physics and just plain good designs.

 

[Pete Mazz]

A.) w/o an SPL meter, should I be able to hear audible differences in the sub's output while changing the phase? (PE 250W plate amp). I have a new layout down here, so I wanted to test that out. If so, foobar (mp3 player/app) can generate test tones really easily...what frequency shoudl the test tone be?

Run the test tone at the xover freq of the sub and mains. Change polarity and listen for highest SPL.

For a quick guide to LA theory, read Jim Griffin's
White Paper on the subject.

Pete

 

[Dave Milne]

w/o an SPL meter, should I be able to hear audible differences in the sub's output while changing the phase? (PE 250W plate amp).

As Pete said, play a tone at the crossover frequency. However, if you are unlucky, it may turn out that your sub is roughly 90 degrees out of phase with your mains at this frequency. In that case you may not hear (or even be able to measure) a difference in amplitude when you change polarity. If this happens, you may want to experiement with other sub positions... or try some test tones above and below the crossover frequency to see which polarity gives you the best average amplitude...

 

[ThomasW]

I think a LA with modest drivers will perform much better
than your typical DIY Point Sources with "modest" drivers..

A LA made with 'modest' drivers would cost quite a bit more than a point source with fairly high quality drivers.

There are some really nice $40 woofers available, the Hi-Vi M8n comes to mind. A LA using 8 drivers/side would be $640 just for the woofers. A MTM with the same woofers would be $160.

I've yet to hear a $25 woofer that's high frequency performance is good enough to reach some of the planar tweeters that are being used in current crop of DIY LA's. These planar tweeters are advertized as being able to operate as low as 2K. That IMO is asking for trouble.

What's really funny is that the low end Maggies (MMG's or MG-1.6's) can be purchased for less than the cost of the cost of raw drivers for some of these DIY LA's. And Maggies IMO are a world class speaker..

 

[Dave Milne]

And Maggies IMO are a world class speaker..

Agreed. But, then, I had a hard time hitting 110dB peaks with the Maggies I've played with...

 

[Brett DiMichele]

Thomas,

Ohh well.. I will form my own opinion once my own LA's are
done (John Janowitz's design using the SA071's and RTW2's).


My ears will be the final judge I guess.

 

[Chuck Bogie]

I've got a case of NSBs, and I'm in the process of cutting holes in the baffles. I'm going to run the NSBs full range at first, and add a line of planar tweets next year (but I may bolt in a single tweet to tide me over). The NSBs are, of course, a compromise, at

 

[Joe Hsu]

Interesting...well, if I were to upgrade, the speaker pair would get about a budget of 800-1000, I imagine. But my other concern with LAs, is what would my surrounds be like?

I guess that first things first, I redo my sub enclosure, and hopefully that'll satiate my need for "new and better" for at least a week or so

 

[ThomasW]

Don't get me wrong. I'm certainly not generically putting down LA's. I have a tri-amped 36" wide by 93" tall planar magnetic/ESL/Leaf LA as my current mains. And I've built and used LA's for several decades.

BTW,Jim Griffin's LA white paper is required reading for all those considering the design and construction of a LA

 

[Joe Hsu]

Yeah, it's quite an extensive read, I'll have to print it out sometime...reminds me of engin class

 

[Brett DiMichele]

Read it... Jim posted it before.. Good read.

I am not designing anything.. I leave that up to the guys
who know what they are doing I am building from plans.

My whole point is that I know an affordable LA is not going
to compete with one that is running the best money can buy.
But still, it's going to be more than I need.