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moray james

University Classic/Dean Horn profile need driver choice help

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" can you please explain how you are going to make bass with such a short horn length?"

 

It won't have any more bass than a LaScala, it needs a subwoofer. Size similar to a Peavey FH1.

 

"The rear chamber of the top driver also needs to be same volume as the triangular chamber of the bottom one."

 

The area between the ramps will connect the back volumes of both drivers.

The 12PE32 is 120mm deep behind the mounting plane (front mounted). The mounting board is 18mm, so the magnet is 102mm deep. If the inner driver is mounted behind its mounting board that is another 18mm, so we are down to 84mm. I was thinking of making the passage 75.5mm (like the stock LaScala), so the magnet sticks into the cone of the other driver by 8.5mm, plenty of room for cone travel.

The mounting hole is 281mm, and the width of the passage is about 75.5mm, so the area at the effective throat is about 212cm (the design calls for 231cm, close enough).

Going either direction from the throat about 32cm (the middle of the 90° bend), and then moving forward 55cm to the mouth gives us a total length of about 82cm (the design calls for 84cm).

With the cabinet about H610mm x D610mm x W760mm the mouth is a bit bigger than required (better a bit big than a bit too small).

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from an old SB

Avg series Avg parall

60.25 60.25 Fs

6.11 1.525 Re

18.55 7.565 BL

0.195 0.295 Qes

3.4 5.3 Qms

0.245 0.245 Cms

250 250 Vas (L)

0.26 Lvc (mH)

0.17 0.17 Rm

 Is that from this article?

post-5045-0-93960000-1428876721_thumb.jp

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That 0.26 mH voice coil inductance may be the lowest I have ever seen. Is it possible that it represents the two voice coils connected in parallel, and not in series as indicated in the article?

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E.G.Beck, love his expose of Globull Warming.

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Haven't had time to do any justice to this thread but wanted to raise a couple thoughts.  In a way, this is a sort of drive-by (tax week and I'm still working on them!) because I can't take time to find all the supporting links.  

Basically, if you pound the web about c15w's, sooner or later you hit Greg Monfort's (among others) post about the earlier ones (green & gold) being different than the later ones (black, like WMcD's auction link).  Seems Nico is one known owner of one of each, but he probably lives farther than it pays me to ship a woofer tester even If he'd help us.  Maybe cart before horse on that, so on to a second point.  

The anecdotal reports just don't "seem" (IMO, and mine only) to track the sort of sims we're getting.  The horn is the horn and I've not checked Edgar's or X's models at all, I just remember what I got when I modeled it (with Mr. Janni's < known bad per Dennis > data).  I mean, the horn is the horn and we can all get close to modeling the horn in our 1-D worlds--we should all be "in the hunt" with respect to the reports.    

Just seems like it's not--the sims vs. the anecdotal reports.  And I agree about the Le, esp in series.  If someone who owns c15w's and is following this thread is game, maybe there's a way we can get some more data and I'll do what I can to get it done.  What we're seeing in most of the sims is 65/70Hz horns.  I think the consensus (?) is that it's a 50-ish Hz quarter-space horn.  

Check (was it?) D-man or (??) Q-man or (both/neither?) that did the Deans.  Somebody else -- Armando as I recall, had a bottom with some EV stuff on top arranged highboy (?)  My impression is that there is "some bass".  It'd be great to hear from them if they're around.  

So if the horn is the horn and the results aren't tracking, I'm thinking we're not modeling the c15w right which means we need more numbers.  

Parenthetically, the throat geometry, angle-cuts and all, may in-fact Be part of what makes these things what they are.  Pretty-much nothing parallel until the 4" sections (mysteriously-absent a reflector).  

< X -- if you're out-there, can you readily/easily change the first corner 90 expansion to having a reflector in it for any of your previous sims just to have a comparison?  If it's unwieldy, skip it. >

I searched "period literature" and exhausted my own stuff hunting for response curves for the Classic or Dean and struck-out.  There's oodles of curves for the models After these, but I'm batting .000.  

This is the best I can do, but I trust Steve and Bruce more than I trust WT3 data (at least _my_ personal WT3):
http://www.audioasylum.com/forums/hug/messages/4519.html

 

There's probably also something to be said for another 15 years of suspension-stiffening since then--after their first 30 or 45 :)

Soooo, say I swag my Sd at 13.5" diameter & I trust Mr. Janni's Cms, Fs, Qe and Qm (and yeah, Le is my own arbitrary value).  Out of my keester, I say 15 ohms is what I get when connected on "10-20 ohms" which needs 3.87 V into it from the generator to get a watt so that's the Eg deal. 

 

This is what I get from a fresh/quick hack (gray/background is masked resonances like Edgar's shallower chamber, black is 30" chamber length honking like gangbusters).  For those who aren't hornresp users, those resonances are pretty strongly overpredicted as given by the preponderance of sawdust.  I'll grant that the moving beeswax seems spooky-light for something with two coils (and apparently two spiders), but it's what it is.  

Could be I'm all-wet, but I think it's the difference between caring a fig about this horn and not.  I think Mr. Cohen knew some stuff and I'm still trying to catch-up.  There have just been so many reports about liking this horn that it seems worth some investigation.  Aw crap, I just helped that dude's auction and sealed my own fate at Never having any of these woofers, didn't I? 

Wow, what a ramble.  Well, almost anything is more fun than finishing my taxes.  Thanks for the space and the time. 

post-53574-0-93160000-1429007376_thumb.j

Edited by grindstone

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Grindstone,

Thanks for the comments and questions. I think that this horn has 50Hz output and plenty of it - it's just 10dB down from the max level and for something that can hit 130dB peak 120dB is still no shame. I actually like this horn and think more people should like it for what it can do to reach the upper bass and mids to integrate with a mid horn. Given that the path length is what it is and Hornresp and Akabak have similar predictions I would have to say I trust the sims as accurate. Until someone provides measurements, I just can't see how this box has a corner frequency anywhere close to 50Hz. The boxes (especially FLH and TH's) I have modeled - the corner frequency is very close to measured - within less than 5Hz. It's really the physics of the 1/4-wave length. No corner reflector or compound oblique angle walls near the throat is going to change that. It may affect ultimate SPL or flatness but not extension. I could easily put a corner reflector but my experience tells me it is a negligible effect given we are looking for deeper bass.

X

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...  And I agree about the Le, esp in series.  If someone who owns c15w's and is following this thread is game, maybe there's a way we can get some more data and I'll do what I can to get it done.  ...  Soooo, say I swag my Sd at 13.5" diameter & I trust Mr. Janni's Cms, Fs, Qe and Qm (and yeah, Le is my own arbitrary value).  Out of my keester, I say 15 ohms is what I get when connected on "10-20 ohms" which needs 3.87 V into it from the generator to get a watt so that's the Eg deal. 

 

 

FWIW; I used the values from the Speaker Builder article above, assumed that the 0.26 mH was for a parallel connection (0.52 mH per VC, which is right in line with other horn woofers that I've encountered), and modeled the C-15W in both series and parallel configurations. Eg has been adjusted in each case for 1W into the series/parallel Re, as appropriate. My results aren't exactly the same as grindstone's because the models are slightly different. But the low frequency performance still shows it to be a 55-60 Hz horn, regardless of which woofer is installed. That's right in line with what we knew all along -- the horn contour and length determine the low frequency cutoff, not the driver.

post-20593-0-04200000-1429019632_thumb.p

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Edgar,

That looks great.  Can you point me to which plan you used for the dimensions in the model?

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Edgar,

That looks great.  Can you point me to which plan you used for the dimensions in the model?

 

See post #22.

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You guys are way more technical than I am so forgive me if this makes no sense; the slot through which the woofer fires in the Classic is much bigger than  in the La Scala or Khorn.

Does this make them suitable to play lower when you boost the lower frequencies like I do with the miniDSP ?

 

It acts like a closed sub that way, I know , and such has very low output. But the bass I'm getting using a bit EQ from 50Hz downwards is defenately  better [as in lower], than I experienced with the Khorns using the same EQ. Defenately lower than around the 50Hz cutoff that the Classic is supposed to have.

 

Again, don't know if this makes any sense but it's all I can think of when comparing the bass ouput of the Classic versus the Khorns.

 

It's a shame I am not familiar yet with using measuring equipment like you guys are; I could swap the K33-e woofers from my Khorns for the C15-W 's in the Classic to measure if it would be a good match.

post-33317-0-75480000-1429342243_thumb.j

Edited by nico boom

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Nico,

First of all, let me say that your build /mods of the Classic look fantastic. The deeper bass has more to do with the length. The aperture or throat in front of the driver affects the HF extension in combination with the size of the front chamber and rear chamber.

Get a mic. Even a cheap one is better than nothing. If all fails, use the built in mic on your laptop.

This one is only $16 and fits your phone.

http://www.parts-express.com/dayton-audio-imm-6-calibrated-measurement-microphone-for-iphone-ipad-tablet-and-android--390-810

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:unsure: Well... I have to admit that I do have a Umike from miniDSP and REW 5.0 installed on my laptop.... but stopped using it after some unsuccesfull attempts to understand it all.

 

The shop at which I bought the mike has planned a instuction-evening for people like me; I am waiting for that to happen.

At the moment we are very bussy with selling our house and looking for another , so there's not much time to fiddle around with the audio-stuff right now.

 

If I make progress in either of these situations " I'll be back"....

 

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Run multiple simulations for various woofers. Most of new woofers don't even come close to University C15W (ehhh my friend some time ago was selling perfect pair of those) nor in FR and especially not for.impulse response. From oldies EVM15L and JBL130 seems decent (but may require back chamber volume corrections).

 

Only one current woofer so far looks promising for me and it's Peavey 1508-8 HE BWX, not as good as C15W but I have not found anything better (especially for impulse response).

Black - Peavey, Gray/Red - C15W

 

post-30216-0-09880000-1436465248_thumb.p

 

post-30216-0-97640000-1436465265_thumb.p

 

Peavey T&S

  • Revc (ohms) 5.32
  • Sd (Square Meters) 0.084
  • BL (T/M) 16.04
  • Fo (Hz) 51.2
  • Vas (liters) 182.4
  • Cms (uM/N) 182.0
  • Mms (gm) 52.90
  • Qms 10.60
  • Qes 0.352
  • Qts 0.341
  • Le (mH) 0.34
  • SPL (1W 1m) 100.3
  • No (%) 6.70%
  • Vd (cu. in. / ml) 19.5 / 319
  • Pmax (Watts pgm.) 1000
  • Disp (cu. in. / ml) 197/ 3229
  • Xmax (mm) 1.9

University C15W  T&S I have used for simulation

  • Sd=856,30
  • Re=5,52
  • Fs=58
  • Vas=232,12
  • Qes=0,23
  • Qms=3,4
  • Le=0,26
  • Xmax=2,4

When I assumed that horn flare rate is 50Hz (not sure if it's true) and calculated Vb and throat for C15W values where almost same as actual University Classic values so Vb=80l and Fhc is great for C15W because it's  545Hz.

For Peavey Vb is 96l and Fhc=300Hz

Edited by Bacek

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Bacek: that's great to see your post, would you also post the T/S numbers for both the Peavey and also most importantly your measured spec for the University driver? That way we can more easily see what drivers will be good candidates for this cabinet. I would like to think that one of the big manufacturers builds a driver which is close to the University in T/S values. Best regards Moray James.

Edited by moray james

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Bacek, try to model Monacor SP-38/300PA

 

Impedance (Z) 8 Ω

Resonant frequency (fs) 48 Hz

Music power 600 WMAX

Power rating (P) 300 WRMS SPL (1 W/m) 99 dB

Suspension compl. (Cms) 0.21 mm/N

Moving mass (Mms) 78 g

Mech. Q factor (Qms) 5.68

Electr. Q factor (Qes) 0.24

Total Q factor (Qts) 0.23

Equivalent volume (Vas) 213 l

DC resistance (Re) 5.9 Ω

Force factor (BxL) 22.0 Tm

Voice coil induct. (Le) 1.2 mH

Linear excursion (XMAX) ±4 mm 

Eff. cone area (Sd) 855 cm2

 

So we get Vb=60l and Fhm=417 Hz. Not bad.

 

Black: Monacor

Gray/Red: Peavey 

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post-60882-0-91680000-1436511761_thumb.j

Edited by Mariusz_

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Monacor looks similar to Peavey, however Fhc=415 is much higher than Peavey. I even like top end of Monacor better. Vb for Monacor is 60 liters. Definitely easier to buy in Europe than Peavey. Slightly better impulse has Peavey.

 

 

But I guess build quality and price is still on Peavey side.

Edited by Bacek

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University Classic with, if I understood correctly C15W and  K-55 squeaker

 

 

 

Measurement of University Dean done by some Russian guys. Looks solid till 500-600Hz.

 

His comment (translated) was:

 

I have never heard such a hurricane feeding bass at the same time for its depth .... The result exceeded all expectations.

 

post-30216-0-87680000-1436530896_thumb.j

 

whole thread is:

 

http://forum.vegalab.ru/showthread.php?t=28445&page=1

Edited by Bacek

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