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Dave A

Super MWM

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On 6/19/2018 at 11:30 AM, jwc said:

Building Big horns is fun.   They sound awesome and to some....look awesome.  

 

I've built my share of them and one principle that sticks in my mind is...... is it worth the increase in physical space to gain say 15-20Hz.    Also more folds can introduce more FR anomalies.  Also the lack of horn expansion vertical can introduce another issues.   

 

To get a bass horn (not sub) to perform  in the 30's without being 1/4 space or 1/8 space......is always big.  Cool as heck to build.   The design posted here is just shy of 60 inches deep with a 67 inch width mouth.  Don't know the height.  If you are gonna use a sub anyway..........my suggestion would be a big straight axis.  Imagine a horn that big but you get to look down the barrel of a 15 staring at you and you can eliminate folds and most of the lack of area expansion in one direction (I would do dual 15's).

 

Either way.....build something that big....we will certainly watch the progress.  You'll have our attention.  If you can get a strong response less that 35Hz and play out to 400Hz with good polars and without big dips.......you have achieved something not commonly done.

 

jc

 

 

We won't know until DaveA can get actual measurements in his shop. Any peaks and dips that occur from the compromises made in NOT expanding the verticals (flat top and bottom, just like the Jubilee and Roy's ported subs), or worrying about annulling via the "right sized" compression chamber, were COMPROMISES to maintain horn LENGTH (approx. 9 feet) at all cost. Increasing the height to use expensive Baltic Birch lumber more efficiently, gave us an improvement. Isn't this height increase exactly what Roy has done with the 1502 and 1802 Theater Subs?? Any peaks and dips can be easily PEQ'd with the Xilica Dave is so fond of and wants to master. But that is another story for another time and beyond the scope of this text.

 

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5 hours ago, dtel said:

I know this thread is not about these subs but it also something people who are building a Super MWM need to be considering, finishes, they are actually harder to clean on the inside than these subs.

I don't object to the direction of this thread at all, and I don't think Dave does either, since it's all related to LOWERING frequencies from VARIATIONS of Bass Horns with Baltic Birch Lumber usage and finish. Now if some smarta$$ started talking about Super Tweeters here, then it would be improper and impolite to do so and we should object. Otherwise, it's all good!

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I didn't think you would mind since a few posts are surely not going to stop this thread, plus people building the SMWM need to think about finishes for easy cleaning later. Dust never seems to slow down or stop.

Thank You, actually that picture of him painting got me thinking about it.

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12 hours ago, ClaudeJ1 said:

Xilica Dave is so fond of and wants to master

YES so fond of all these new fangled things. It will be OK once I get through it all at least once. First is the struggle with foreign logic and then one day it all clicks and off you go. It is quite frankly beginning to sound really nice and I know it is not where it should be yet.

 

  I think threads that ramble at times are informative and or amusing so have at it. I elected to use the brown Duratex precisely for cleaning. Every once in a while a vacuum and brush nozzle is all it will ever get and what dirt is there does not show up like it does on black. PLUS if I let it all get dirty and never clean it the appearance will still be uniform. 

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6 hours ago, dtel said:

Thank You, actually that picture of him painting got me thinking about it

I think this is known as cosmic retribution. You are one of the people that started me down this path so it is only right that I have done something of value to you in return. Have I told you how filthy those speakers looked in the pictures yet?

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13 hours ago, ClaudeJ1 said:

We won't know until DaveA can get actual measurements in his shop. Any peaks and dips that occur from the compromises made in NOT expanding the verticals (flat top and bottom, just like the Jubilee and Roy's ported subs), or worrying about annulling via the "right sized" compression chamber, were COMPROMISES to maintain horn LENGTH (approx. 9 feet) at all cost. Increasing the height to use expensive Baltic Birch lumber more efficiently, gave us an improvement. Isn't this height increase exactly what Roy has done with the 1502 and 1802 Theater Subs?? Any peaks and dips can be easily PEQ'd with the Xilica Dave is so fond of and wants to master. But that is another story for another time and beyond the scope of this text.

 

Im talking about dips after 100Hz.  I doubt that would matter with 1802 or "subs". 

 

It matters for basshorns...or LF.  Yes the jube has a substantial dip....making the horn longer....could make that dip worse.

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18 hours ago, jwc said:

Im talking about dips after 100Hz.  I doubt that would matter with 1802 or "subs". 

 

It matters for basshorns...or LF.  Yes the jube has a substantial dip....making the horn longer....could make that dip worse.

Higher frequency dips can be PEQ'd with less Intermodulation Distortion than lower frequency rolloffs, especially below horn cutoff. A those longer lengths, directivity becomes a bigger issue, which PEQ can't fix, but crossing lower to a midrange driver that can do 300 Hz. is better than trying to cross at 500 from that big bad horn.

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3 hours ago, Dave A said:

First is the struggle with foreign logic and then one day it all clicks and off you go.

 

Like Hewlett-Packard's RPN.  Takes a minute to get used to, and thereafter it's difficult to use a "regular" calculator 'cause it's so cumbersome.  (RPN for those unfamiliar.)

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4 hours ago, Dave A said:

I think this is known as cosmic retribution. You are one of the people that started me down this path so it is only right that I have done something of value to you in return. Have I told you how filthy those speakers looked in the pictures yet?

Well, thank you, no you haven't told me lately but that's OK. It's not as bad as it looks but still if anyone is here and wants to help. :lol:

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5 hours ago, Dave A said:

I think threads that ramble at times are informative and or amusing so have at it.

 

We're just keeping it alive 'til you get back with your data.

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2 minutes ago, glens said:
5 hours ago, Dave A said:

I think threads that ramble at times are informative and or amusing so have at it.

 

We're just keeping it alive 'til you get back with your data.

I figured it would just resume when needed.

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But then he'd have to hunt for it.  This way it falls ready to hand.

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16 hours ago, glens said:

 

Like Hewlett-Packard's RPN.  Takes a minute to get used to, and thereafter it's difficult to use a "regular" calculator 'cause it's so cumbersome.  (RPN for those unfamiliar.)

I got used to RPN with an HP-45, the original "electronic slide rule" back in college. I can't use a calculator with an = key on it very well. RPN is far superior in every way. I still have my HP41 CV with all the modules, since on of my best friends worked for HP and got me 70% off. So I got a $1,000 worth of Calculator stuff for $300 back in 1983, about the time I got a Sony CD player (the only one available then). Still have the calculator, but now I downloaded one just like it for free for my iPhone. 

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I very highly recommend Free42 in case that's not what you got.  There's a downloadable PDF manual that'll take several days to peruse.  Still got the original 42S in perfect working order.  Those double-shot keycaps look as good as new and still have all their tactile glory.  Also among others have a 48S that I picked up new from HP for $25 when they unloaded their remaining stock saved for warranty after it was discontinued.  Doubt they had many warranty claims on the calculators made through the '90s.  Don't know about for Apple, but the 48 (S and G) is also available for computers / devices.  HP released the ROMs for them for just such purpose, though if you had a 48 you could send your own ROM out the serial port.  But the 48s aren't RPN, they're RPL and you can program them at 3 levels for increased operational speed if you know ahead of time what kind of objects are on the stack so it doesn't have to check them first and direct the work to the proper routines.  Or if you can and want to program the bare metal.

 

One nice thing about the 48s is programs / variables are stored in a directory structure.  If what you want is in the working directory that's what'll get used.  If not and there's one of the same name in a higher-level directory, that's the one it'll use.  Different objects in different directories gan have the same name, unlike with the "equivalent" (ahem) TI calculators, where a name can only be used once globally.

 

A posting about the X Window System program "x48" on HP's dial-up mirror of comp.sys.handhelds (or the other group, can't think of it) was what introduced me to Linux! 

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Glens: Thanks for the recommendation. I downloaded the Windows version. I don't need the power of that calculator and I don't want to learn a new one. The HP-41 has more of the things I use all the time, namely Polar/Rectangular conversions right on the buttons. The hardware version I have still works, and has the Real Estate modules I've used plus, I have a 12C in hardware and in virtual form on my iPhone. I'm sure it's everything you say it is, but not necessary for my routines. 

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The menu for conversions is Shift 5 "Convert".  Only one more button press unless yours are unshifted.  If you get a few minutes, give it a whirl.  I guess it's mostly 41-compatible.  The thing about the real hardware is it's as pocketable as a smartphone.

 

And seeing both the x and y stacks is hard to downgrade from.

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19 hours ago, glens said:

...was what introduced me to Linux!  

 

Everyone starts somewhere. I was working for a guvmint contractor in '92, and they used Silicon Graphics workstations, which ran a flavir of unix called Irix. The owner badmouthed linux all the time. There weren't enough wotkstation for all the employees, but they did have PCs. One of the new programmers made a floppy boot disk into a slackware partition and wrote all his code in his own office. When he needed to compile and test he would move it to the SG server. The boss was never the wiser and the programer was way more productive.

 

Bruce

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That would've been a couple years prior to my cherry getting popped, but even when I started (opting for Slackware) one had to be pretty savvy or get that way to use it.  Not like today...  Trying to use Microsoft Windows is now like trying to use a calculator with an "=" key :)

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Probably more accurate to move it closer to the date you started, late '93 into '94. Sheesh... long ago and far away...

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On 5/25/2019 at 6:55 PM, Marvel said:

Probably more accurate to move it closer to the date you started, late '93 into '94. Sheesh... long ago and far away...

You guys are just a couple of "kids." But since my grandmother, who was born the same year as PWK, outlived him by 6 years, I'm hoping I got some of those genes!!!

 

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