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Old 27th January 2011, 04:15 PM   #141
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Join Date: Jul 2007
Location: Ottawa
It was a terrific weekend - glad I made it there this time! Thanks to everyone who contributed in any way. There was more stuff available than I had time to properly listen to. What I learned, foremost, is that my ears aren't that educated. Listening to better gear than I have was an excellent opportunity to improve on that.

I thought all the subs were impressive considering the volume of the room. Liked the FLH the best, with the TH a close second. The two smaller boxes didn't do as well, but I didn't identify the issue as distortion the way some other people did.

Really liked Pierre's speakers - first time I've heard ribbons. Swapping amps on them was entertaining. The Ariels, RBRs, and Dave's black boxes were all great too. Seeing the measurement process and hearing people talk about it was valuable.

I would have liked to spend more time listening to the headphones and hp amps. Since they are small and easy to move I can hope they are back at the next meet... hint, hint.

The CDs I brought:
John Martyn - Solid Air (Saturday only, all others Sunday)
Amazon.com: Solid Air: John Martyn: Music

Julia Fordham - Porcelain
Amazon.com: Porcelain: Julia Fordham: Music

John Martyn - One World
Amazon.com: One World (Dlx): John Martyn: Music

Colin James - Bad Habits
http://www.amazon.com/Bad-Habits-Col...6148445&sr=1-4

Al di Meola - The Grande Passion
Amazon.com: The Grande Passion: Al Di Meola World Sinfonia, Al Di Meola: Music

Thanks again to all who showed up.

bearberry
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Old 27th January 2011, 04:16 PM   #142
opc is offline opc  Canada
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Hi John (multisync),

I'm pretty sure I have a pair of 55-0-55 toroidal transformers at 500VA each, but I need to double check that they're still around.

If I can dig them up, then you're welcome to them.

I'll let you know this evening.

Cheers,
Owen
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Old 27th January 2011, 05:23 PM   #143
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christmas may come sooner for me!!!!!!!!!!!!!
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Old 27th January 2011, 11:46 PM   #144
opc is offline opc  Canada
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Hi John,

I've got good news! I just went through my transformer bin, and I think I have just what you're looking for:

ATC Frost 122.5 VCT @ 5.9A for 725VA

I've attached a picture for reference.

I've got a pair of them, and they're yours if you come and get them. Do you need one or both? Send me a PM and we can figure out the details.

Cheers,
Owen
Attached Images
File Type: jpg IMG_5855.JPG (318.8 KB, 126 views)
File Type: jpg IMG_5856.JPG (267.3 KB, 122 views)
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Old 28th January 2011, 01:58 AM   #145
Mark Kravchenko --- www.kravchenko-audio.com
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I vote for the glass of wine with the iphone and the soldering station. You can keep that nasty black keyboard.

I have lots of transformers!
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Old 28th January 2011, 06:06 PM   #146
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Before getting to the comparison, I wanted to mention the “set-up” a little bit, because I’m not sure that some of those details have received as much coverage as they deserve. I have read enough to know that although subs might just look like big boxes, there are actually many ways to design a sub enclosure – you have to juggle your trade-offs, since you are balancing enclosure size, driver features/parameters, amplifier power requirements, etc. Given all these variables, comparing 4 different sub designs sounds like a recipe for one of those “apples-to-oranges” comparisons.

I was really looking forward to this comparison, however, because some clever DIY’ers tried to make this into an “apples-to-apples” comparison. I think that Mark did something remarkable i.e. he built 4 different designs using basically the same driver complement (2 x CSS SDX 7, I believe) – so no sub had a better driver than another sub. Then with Adam’s 12-channel amp & prep work, it was possible to easily switch between subs while playing at a consistent output level – so although these designs are not equally efficient, judging was not skewed by efficiency or amplifier sound qualities. I give credit to all those responsible, because I wouldn’t have expected to see these 4 different sub designs compared on such a level playing field. The space was a smallish community hall, but certainly bigger than the average listening room, and the subs were gathered in one corner location (reinforcement).

I made the following notes during the classical selection (organ; orchestra; Saint Saens?) that was played once through on each sub: The front-loaded horn (#1) definitely had the most rumble, and handled the bass the best. The tapped horn (#2) did not go as low or “rumbly” as the front-loaded horn; it seemed a bit boomy at first, but as the piece went on, it seemed to be fairly musical, and almost as deep as the front-loaded horn…so it was pretty good, but just not as good. The unhorn (#3) did surprisingly well for its size; it didn’t match the other two i.e. not the best. The front-driver, rear ported sub (#4) was not as good…it couldn’t play as well, and I thought it was “muddier”. (End of notes.) Having said that, it should be mentioned that the port on #4 may have been too close to the surface behind it, because after it was moved slightly forward during one of our two rounds of comparisons, it sounded better.

I was looking forward to 1 or 2 more rounds of comparisons, using other music, but unfortunately, that didn’t really pan out. I heard a bit of the CD I’d brought for the purpose of testing other bass-handling qualities – Thunder, by S.M.V. (track 2) – I think it was played on #1, but I didn’t make any notes. I would suggest that we really didn’t manage a proper critical comparison after the first round, so the second round sort of fizzled away. Overall, I think that the consensus (verified with my son & his teenaged ears) was that #1 and #2 impressed the most.

- Ron
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Old 28th January 2011, 06:13 PM   #147
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Follow-up to my last post:
I should have re-read the earlier posts before I drafted mine...Mark's # 122 covered the prep info better than mine did. However, in his post, he was (surprisingly) modest about what he did.

- Ron
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Old 28th January 2011, 06:27 PM   #148
Mark Kravchenko --- www.kravchenko-audio.com
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Just the facts sir.....

If a designer waxes eloquently on the merits of his work while the audience is quite the silence becomes deafening!
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Old 30th January 2011, 04:25 PM   #149
Mark Kravchenko --- www.kravchenko-audio.com
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Ron I never thanked you for your comments on what you heard.

Your perceptions are both critical and fair. Just as I like em!

Mark
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Old 31st January 2011, 01:57 AM   #150
DDF is offline DDF  Canada
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Hi folks, here are the promised loudspeaker measurements. Sorry it took so long to get these posted, I was traveling all week (its nice to be home!).

Marks "Anna" ported sub:
Picasa Web Albums - Dave - DIY Audio Ott...
Picasa Web Albums - Dave - DIY Audio Ott...

Mark's "Horn" Sub Near Field
Picasa Web Albums - Dave - DIY Audio Ott...

Mark's "UnHorn" Sub Near Field:
Picasa Web Albums - Dave - DIY Audio Ott...

Mark's "Tapped Horn" Sub Near Field
Picasa Web Albums - Dave - DIY Audio Ott...

Estimate of Rick's Quatro Sub Near Field. Rick, I added the passive radiators to the driver assuming they were all ~ the same diameter.
Picasa Web Albums - Dave - DIY Audio Ott...

Adam's Line Source center channel (Adam, were these CSS EL70s?)
Picasa Web Albums - Dave - DIY Audio Ott...

Adam's EV driver (Adam, sorry, can't recall the part number on this)
Picasa Web Albums - Dave - DIY Audio Ott...

Pierre's PHL 1340 midrange-woofers and Aurum Cantus G2 ribbons in ported MTM tower configuration. Crossover design by André Perreault @ e-Speakers:
Picasa Web Albums - Dave - DIY Audio Ott...

Rick's RBR Recession Buster Reference (http://www.clearwaveloudspeaker.com/RBR/infoRBR.html)
Picasa Web Albums - Dave - DIY Audio Ott...

Owen's Ariel. Owen, sorry but the file was corrupted. The response looked very similar to this one, captured from Lynn Olson's web site, except I don't recall the tweeter level raising back up above 7 kHz:
Picasa Web Albums - Dave - DIY Audio Ott...

Dave's ScanUsher:
Picasa Web Albums - Dave - DIY Audio Ott...

Dayton ND-105-4 Frequency Response. For this one, I modeled the effect of the high tech vodka cabinet, so what's shown is "infinite baffle". John, it has a pretty big dip at 3 to 5 kHz. I see a number of designs where the crossover purposely puts this in, to make it more relaxed on music, but it would detract from voice intelligibility.
Picasa Web Albums - Dave - DIY Audio Ott...

And finally, the Dayton ND105-4 #1 TS parameters:
0.134 "RMSE-free Ohms"
71.212 "Fs Hz"
3.951 "Re Ohms[dc]"
31.492 "Res Ohms"
4.748 "Qms "
0.596 "Qes "
0.529 "Qts "
0.488 "L1 mH"
0.535 "L2 mH"
1.489 "R2 Ohms"
0.127 "RMSE-load Ohms"
0.004 "Rub-index "

Be happy to send the raw measurement files to anyone (PM me here).

I'll be posting my loudspeaker design presentation in a few days (or using Mark's terminology, my "Un-Presentation" )

Dave

Last edited by DDF; 31st January 2011 at 02:23 AM.
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