Adire's new 8"

[Hank]

Jon, what do you think about it for the RD-50's dipole? Wide BL curve, 12mm Xmax one-way...

Also, small sub driver for home/auto.

[Hank]

Well, that certainly created a groundswell of excitement :Z :Z :Z

oke:Alright, how 'bout 32Hz Fs, 6.5 Qms, .42 Qes, .40 Qts, 36L Vas, .45L Vd? $79?:yesnod:

[TacoD]

Impressive specs, but how does it sound ...

[ThomasW]

Well it's pricey and doesn't have a top end that can compared to the now much less expensive HiVi M8a.

And IMO using 8" drivers for subs or even pure woofers is asking to trouble if one wants even reasonably high output

[JonMarsh]

Well, that certainly created a groundswell of excitement :Z :Z :Z

oke:Alright, how 'bout 32Hz Fs, 6.5 Qms, .42 Qes, .40 Qts, 36L Vas, .45L Vd? $79?:yesnod:

Alas, some of us worker droids don't get to check the forum very often while we're traveling our butts off....


Seriously, pretty good Xmax and BL linearity, upper end would probably be OK crossing over to a RD50 or Rd75. The roll off above 100 Hz suggests a higher Le than the published spec, but who knows? Wish it were a cast basket, not stamped- the bigger panels for a stamped version might be a problem for woofer noise in a dipole. Last, I wonder how the lower mid response bump in a diople will look.

Considering the point they make about being a "standard" 8" driver, not oversize (like most of my favorite 8" are- anywhere from 8-1/2" to 9", the big surround means the actual cone Sd is a bit smallish for an 8".



Still, the ultimate test is how it sounds....

Only other thing potenitally problematic is the somewhat low sensitivity - wouldn't be a problem with an active crossover version, but for a 4 ohm driver, it's a bit on the low side, especially with a pasive crossover incorporating some EQ. Hmmmm..... could be just the thing to "klone" some of the speakers from Genesis and others using long throw 8's as "subs", like 2 or 4 per cabinet.

I'm also curious to see the Dayton 8" coming out the end of this month, that Mark K has tested a prototype of.


~Jon

[Dennis H]

I don't really see the point of an uber-Xmax 8". Usually, you would use an 8", rather than a 10" or a 12", because you want to cross it high. But crossing high precludes big Xmax if you want to keep IM (doppler) distortion low.

IM distortion % = 0.91 * (max 1-way excursion in mm) * (max freq in kilohertz)

So, if you cross at 500 Hz, max excursion = about 2 mm if you want to keep IM distortion under 1%.

[JonMarsh]

I don't really see the point of an uber-Xmax 8". Usually, you would use an 8", rather than a 10" or a 12", because you want to cross it high. But crossing high precludes big Xmax if you want to keep IM (doppler) distortion low.

IM distortion % = 0.91 * (max 1-way excursion in mm) * (max freq in kilohertz)

So, if you cross at 500 Hz, max excursion = about 2 mm if you want to keep IM distortion under 1%.

What you're pointing out is something often forgotten in the quest to make any kind of two way system- for example, something like the Seas 7" two ways, with Excel woofer, crossed over about 2 kHz+. The quoted relationship would pretty much shoot down such a system, hmmm? Can you point us in the direction of the source material or paper from which the relationship was derived?

Maybe we're more tolerant of 1% IM because we're so used to hearing it in many systems, and the order of distortion from the speaker, compared with a negative feedback system with 1%, is less musically damaging. But certainly it must take away from a sense of ease or clarity. But this may also help my 8" two way, becase it only runs up to ~1.2 kHz on the woofer, instead of double that for most two way systems.

OTOH, taking for example, the Arvo project, there's no doubt that there's an ease and clarity in the mids and presence region which the ported box two way using the same 8" can't match- this could be more of it than I realize. In the Arvo's the 8's aren't seeing much excursion, because there's two, and I only run them down to ~225 Hz, unlike the Orion which takes them to a 100 Hz crossover... I wonder if that helps, too?


~Jon

[Hank]

Only other thing potenitally problematic is the somewhat low sensitivity

Actually, that's the one thing that jumped out at me, rather than SD, etc.
And I forgot about the Dayton coming out next month. Will it be stamped or cast?

[Dennis H]

Ironically, the formula came about from a discussion of this very driver on the Mad board back when it was a gleam in Dan's eye. John K brought up the IM distortion bit and presented a long, confusing formula that I'd never be able to remember. I wrestled with the algebra, cancelled out all the unnecessary stuff and got it down to that simple one. After a bit a prodding, John K admitted my simple one gave the same result as his complicated one.

Well shucks, I shoulda known. SL has already been there, done that, made a buck selling the t-shirts. He comes up with the same thing except for the units.

In his example, (sideband amplitude)/(original high tone amplitude) is 0.09 (9%) for a 5mm driver and a 2kHz tone.

http://www.linkwitzlab.com/frontiers.htm#J

http://www.linkwitzlab.com/images/graphics/doppler1.gif

[Dennis H]

About the clarity of the mids, I think that may be a lot of the story. Dennis Murphy commented about the mid clarity being one of the biggest improvements when he turned his MBOW1 2-way, with a 5" woofer, into a 3-way by crossing in a 10" at 350 Hz.

[JonMarsh]

Ironically, the formula came about from a discussion of this very driver on the Mad board back when it was a gleam in Dan's eye. John K brought up the IM distortion bit and presented a long, confusing formula that I'd never be able to remember. I wrestled with the algebra, cancelled out all the unnecessary stuff and got it down to that simple one. After a bit a prodding, John K admitted my simple one gave the same result as his complicated one.

Well shucks, I shoulda known. SL has already been there, done that, made a buck selling the t-shirts. He comes up with the same thing except for the units.

In his example, (sideband amplitude)/(original high tone amplitude) is 0.09 (9%) for a 5mm driver and a 2kHz tone.

http://www.linkwitzlab.com/frontiers.htm#J

http://www.linkwitzlab.com/images/graphics/doppler1.gif

Thanks, Dennis. I travel so much on business this last year, I often miss some of these discussions; I think I vaguely remember something referring to the discussion, but didn't see the original!

~Jon

[JonMarsh]

Actually, that's the one thing that jumped out at me, rather than SD, etc.
And I forgot about the Dayton coming out next month. Will it be stamped or cast?

The new Dayton is a cast frame driver....

[Brian Bunge]

Ummm...where can I find info on this Dayton?

Howdy Hank!

[BrianJD]

Ummm...where can I find info on this Dayton?

Howdy Hank!

Brian, They havnt been released yet but Mark K has been doing testing on the 5", 8", & 10" prototypes. I think theres a 6 & 7" also? The 8" is here...

http://206.13.113.199/ncdiyaudio/mark/8%20inch%20woofer%20test%20group/8%20inch%20woofer%20test.htm

87db, cast frame, aluminum cone, aluminum phase plug, faraday rings , shielded.



Jon & Thomas, I was wondering if you have ever tested the Peerless XLS 8" (205SWR39XLS) $63. I think its exclusive to Solen. It might be one to consider, but then again you guys like those metal cones. It looks like the Dayton will be the most cost effective :T and it does have some nice features.



Size VC Type db W Z Re Le Ce Fs Vas Qms Qes Qts Xmax

21cm 39mm Paper 90 150 8 5.9 .56 16 29 53 4.1 .40 .36 ±10

[JonMarsh]

For big woofer applications, I've preferred the bigger XLS, if I was going to go Peerless- but these days I like the TC2+ even better.

My favorite peerless driver is the 6-1/2" HDS version without the phase plug. It's a very nice midwoofer with good Xmax; still prefer to cross it lowish, but the well behaved cone makes the crossover easy to do.

I've never really been looking for an 8" woofer that much myself... most of them are only good for "woofer duties" (below 400 Hz) because the majority get into some kind of cone problem around 700-800 Hz. Witness the Dayton, even. Exceptions are the Seas W22, and to a lesser extent, the HiVi M8a.

It will be interesting to see how this new Dayton line stacks up. The basket on the pictured model looks a lot like some HiVi models; wonder whos making those for PE?


~Jon

[Hank]

87db, cast frame, aluminum cone, aluminum phase plug, faraday rings , shielded.

Hi Brian! I know you won't be able to resist those ALUMINUM cones. BTW, any prospects?

Jon, I just looked at those test graphs - did you look at 'em? I think the Dayton is FINE. I believe we may have a candidate for the line array. Hmm...wonder what the dipole performance would be like...
I don't think I want to by any Vifa P-21's :E

[JonMarsh]

Yeah, I'd hold off on the P21's at this point.....

The weird thing is, I could swear I saw drivers on the Swanspeaker site about three months ago that looked just like these new Dayton's- black aluminum cones, bullet phase plug, cast frames, but that series couldn't be found last time I looked, and now all the drivers are off the Swan Speaker site.

For the line array, the Dayton's could really be the ticket crossed over about 500-600 Hz. Don't know how the efficiency would work out- if it was an active setup, no sweat, of course. If I went active, I'd probably do a simple buffer amp for the high pass; or maybe use a subractive circuit to get the high pass response. BTW, I'm sitting on quite a few NOS BUF-03. It would be a good part in that application- I'm using some for the LF equalizer for the Arvo's, which will use a passive T-bridge filter for the LF EQ. (with a tip of the hat and nod to SL). I'm pondering what the issues may be with the lower mid dipole hump- where to deal with that. I get around it in the Arvo's by my choice of crossover points and crossover shaping.

BTW, you wouldn't believe how clean the SS9800 and M8a combo in MTM sound above 200 Hz in dipole... the RD's will have their work cut out for them to compete.

I just need some time off.... looks like I'll be in Singapore over Thanksgiving.

[Hank]

looks like I'll be in Singapore over Thanksgiving

Uh-oh, looks like your corporate abuse continues. Anyway, the Dayton lookes very interesting indeed. Maybe next year some dipole line arrays will materialize around here.