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Lilmike's Cinema F-20 - Page 4

post #91 of 1589
4/26/11 at 2:36pm
Thread Starter 
The Behringer A500 is decent, but leaves a little bit on the table power-wise, and won't do a 4-ohm load bridged. A small pro-amp like the little Crown, Peavey, or Marathon might be a decent option too.
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post #92 of 1589
4/26/11 at 2:44pm
Quote:
Originally Posted by lilmike View Post

The Behringer A500 is decent, but leaves a little bit on the table power-wise, and won't do a 4-ohm load bridged. A small pro-amp like the little Crown, Peavey, or Marathon might be a decent option too.


The crown 202 http://www.crownaudio.com/amp_htm/xls.htm seems to fit the bill, although it wouldnt be bridged either. Do you just pick a channel and have the AVR send it the LFE signal as usual?
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post #93 of 1589
4/26/11 at 3:20pm
Thread Starter 
That does not look bad at all. Might be hard to find brand new though - I think that model has been superseded by the XLS 1000. The new one has some nice features, but they sort of missed the boat on the DSP crossover functions.

Yup, wiring it up is simple as that. Adjust gains properly and you're good to go.
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post #94 of 1589
4/26/11 at 10:13pm
Thread Starter 
Updated the Cutlist in Post 1 to match the instructions I'm working on.
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post #95 of 1589
4/26/11 at 10:23pm
Quote:
Originally Posted by lilmike View Post
Updated the Cutlist in Post 1 to match the instructions I'm working on.
Both side panels can be cut from 1 sheet of Baltic. Can the rest of it be cut from 1 other sheet?

The Anarchy was cut from 1 sheet of 1/2" and packed up it weighed 36lbs. That didn't take the full sheet though, but a good chunk of it. Average shipping was between $18 - $28.

This bigger one.......shipped in two boxes?????? Maybe $200 max to your door?


I should shut up.
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post #96 of 1589
4/26/11 at 11:52pm
Quote:
Originally Posted by Erich H View Post
Both side panels can be cut from 1 sheet of Baltic. Can the rest of it be cut from 1 other sheet?

The Anarchy was cut from 1 sheet of 1/2" and packed up it weighed 36lbs. That didn't take the full sheet though, but a good chunk of it. Average shipping was between $18 - $28.

This bigger one.......shipped in two boxes?????? Maybe $200 max to your door?


I should shut up.
Don't shutup!!!!

Lots of people would love a sub that can be shipped to them ready for assembly.
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post #97 of 1589
4/26/11 at 11:59pm
Thread Starter 
Quote:
Originally Posted by Erich H View Post
Both side panels can be cut from 1 sheet of Baltic. Can the rest of it be cut from 1 other sheet?

The Anarchy was cut from 1 sheet of 1/2" and packed up it weighed 36lbs. That didn't take the full sheet though, but a good chunk of it. Average shipping was between $18 - $28.

This bigger one.......shipped in two boxes?????? Maybe $200 max to your door?


I should shut up.
Nope - it is ~2 2/3 60X60 sheets. 22 3/4" X 60 left as scrap from the last sheet
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post #98 of 1589
4/27/11 at 12:21pm
Is there anything else i will need to run in the signal path? necessary EQ or DSP or whatever? I am unfamiliar with in-line stuff like that but will get something and learn...
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post #99 of 1589
4/27/11 at 1:34pm
LM,

Sorry to go back to this, but those steps you outlined for me in post 23, would either a 3 or 5 ohm resistor work? I have some little Vishays in 3 and 5 but no 4 ohms ones lying around.

The 3 would be closest to the re of my sub(s) which is 2.7 (AV15-H).

Thanks again.

James
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post #100 of 1589
4/27/11 at 6:52pm
Thread Starter 
Quote:
Originally Posted by exojam View Post

LM,

Sorry to go back to this, but those steps you outlined for me in post 23, would either a 3 or 5 ohm resistor work? I have some little Vishays in 3 and 5 but no 4 ohms ones lying around.

The 3 would be closest to the re of my sub(s) which is 2.7 (AV15-H).

Thanks again.

James

I don't worry that much. I use 2.00 volts into 4 ohms for a 4-ohm nominal speaker and 2.83 volts into 8 ohms for an 8-ohm nominal speaker.

I also use at least 10W power resistors. Not sure if the Vishay's you're referring to are 10W. The pic is a 120W 4-ohm power resistor like I use, and I've warmed it up pretty well.
LL
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post #101 of 1589
4/27/11 at 8:13pm
LM,

Thanks for the information. Both the 3 and 5 ohm ones are 25W.

James
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post #102 of 1589
4/27/11 at 9:34pm
Thread Starter 
Quote:
Originally Posted by exojam View Post

LM,

Thanks for the information. Both the 3 and 5 ohm ones are 25W.

James

Hmmm. Wire in the 3 ohm, set your voltage to 2.00, then try the 5 in its place, see if there is any variation. If the amp voltage behaves, you might be OK. Picking up a pair of 8 Ohm 20 W resistors at Radio Shack next time you drive by will have you set for 4, 8, and 16 ohm drivers, they're $2.50 each.
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post #103 of 1589
4/28/11 at 4:21am
Thanks again LM.

James
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post #104 of 1589
4/28/11 at 4:49am
How does this compare to the THT?
If a more powerful driver was installed, would this produce below 20hz? What specs in the driver are desireable in this design to produce sub 20hz?

Thanks!
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post #105 of 1589
4/28/11 at 11:51am
lilmike, do you recommend screws to hold the boards in place while the PL dries, or is it ok to use 18 gauge brads?
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post #106 of 1589
4/28/11 at 6:18pm
Thread Starter 
Quote:
Originally Posted by Maxjr View Post

lilmike, do you recommend screws to hold the boards in place while the PL dries, or is it ok to use 18 gauge brads?

With 3/4" material, I use screws. I leave them in place. A little bondo on the screw heads, then sand and paint....

18 gauge brads might work, but 1 1/4" is probably too short, I'd suggest 1 3/4" minimum. I've not tried brads in horn construction with 3/4" material, but have used them successfully for years when building conventional cabinets out of MDF and ply.
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post #107 of 1589
4/28/11 at 6:28pm
Thread Starter 
Quote:
Originally Posted by Hawkson View Post

How does this compare to the THT?
If a more powerful driver was installed, would this produce below 20hz? What specs in the driver are desireable in this design to produce sub 20hz?

Thanks!

Both are offset-driver horns. The THT is big, the F-20 is bigger still, but is a different shape, which may fit some rooms better. While the THT is a touch smaller, the F-20 plays a touch lower. Both get plenty loud. The F-20 is fairly flat without a corner, the THT needs to be placed in a corner for the flattest response. The MFW driver works in both, as do more expensive drivers. In both cases, a more powerful driver will not lengthen the horn, which is what is needed to make the horn play lower. Horn length is what sets the low corner.

The wavelength of 15 Hz is about 23 meters, 20 Hz is about 17 meters. Admittedly - we're using quarter-wavelength designs here, but still - you would need 1.25 meters of additional horn length (which equates to about 2X the cabinet volume) to get to 15 Hz, as well as a driver that works to 15 Hz.

The 12-step program (Assembly instructions.... ) has been added to Post 1.
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post #108 of 1589
4/29/11 at 5:40am
Say lilmike, I know you said you use the neutrik speakon connectors, so hopefully you can shed some light on the installation of the connector into the sub box itself.

I'm using the 2-pole version and have measured the plastic cylinder of the connector body that fits into the sub cabinet with a caliper and get close to 59/64inches (0.9219inches).

So, I'm considering a forstner bit of 15/16inches (0.9375inches) to drill the hole througth the sub cabinet and use some kind of glue/caulk in the hole/on the inside cabinet to seal the speakon connector airtight.

Any recommendations from users who have done this before would be appreciated.
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post #109 of 1589
4/29/11 at 7:51am
Thread Starter 
Quote:
Originally Posted by BruceD View Post

Say lilmike, I know you said you use the neutrik speakon connectors, so hopefully you can shed some light on the installation of the connector into the sub box itself.

I'm using the 2-pole version and have measured the plastic cylinder of the connector body that fits into the sub cabinet with a caliper and get close to 59/64inches (0.9219inches).

So, I'm considering a forstner bit of 15/16inches (0.9375inches) to drill the hole througth the sub cabinet and use some kind of glue/caulk in the hole/on the inside cabinet to seal the speakon connector airtight.

Any recommendations from users who have done this before would be appreciated.

I use a 15/16" Forstner bit, works great.

A little bit of PE speaker caulk or duct seal under the flange and around the barrel has worked as a sealant so far. The F-20 has a speakon through the access cover, and it sealed up fine using this method.
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post #110 of 1589
4/29/11 at 6:43pm
I've been thinking about the access cover a bit lately and have been wondering if there is a secure way of making it flush mounted with the rest of the side panel? This will give users the flexibility to lie the cab on its side on either of it's largest panels without having the access panel in the way. It will also add a bit to aesthetics. However, the speaker terminal will also most likely be mounted on the access panel, so maybe the point is moot? What do you guys think?

On my anarchy build, I skipped the access cover all together and ran the speaker wires straight out through the mouth of the horn. This made a simpler build and skipped me having to buy and mount terminals. However, this being a front loaded horn (instead of a tapped horn), I don't have that option anymore.
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post #111 of 1589
4/29/11 at 7:11pm
Thread Starter 
I made it like this:


I used the cutout for the access panel to fill the hole, and added a flange inside to fasten it to.

Sorry if the instructions are not clear enough on this, guess I could have added pictures.
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post #112 of 1589
4/29/11 at 7:33pm
Thread Starter 
Quote:
Originally Posted by Maxjr View Post

I've been thinking about the access cover a bit lately and have been wondering if there is a secure way of making it flush mounted with the rest of the side panel? This will give users the flexibility to lie the cab on its side on either of it's largest panels without having the access panel in the way. It will also add a bit to aesthetics. However, the speaker terminal will also most likely be mounted on the access panel, so maybe the point is moot? What do you guys think?

On my anarchy build, I skipped the access cover all together and ran the speaker wires straight out through the mouth of the horn. This made a simpler build and skipped me having to buy and mount terminals. However, this being a front loaded horn (instead of a tapped horn), I don't have that option anymore.

Lots of options.

Drill a hole in the bottom of the chamber, wire it out the mouth.
Drill a small hole in the chamber where it is needed, run the wire through, and put the input wherever you want.

I'm lazy. That's the only reason it is where it is...
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post #113 of 1589
4/29/11 at 7:49pm
That's exactly what I was thinking about! Looks great. Thank you for the picture! It's worth a thousand words. I think I may go with your suggestion and drill a hole through the chamber and run the wire out of the mouth. What do you recommend to use to patch around the speaker wire in the hole area?

Also, this question may not be the best posed here, but I just thought of it and haven't read the answer in any other horn thread. What is the life expectancy of the driver in a horn? Is it expected to be less or significantly less than the same driver in a sealed or ported enclosure? I'm just thinking out loud here and wondering how the effects of the horn loading affect the driver's life.
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post #114 of 1589
4/30/11 at 5:04am
Quote:
Originally Posted by lilmike View Post

You're welcome.

As it looks currently, I'll have 4 designs in my Cinema series, each with a variation or two. I have models and ideas for folds for a large tapped horn with a single 15" driver, and an F3 below 20 Hz, but I don't have a dimensioned fold yet, nor do I have a driver to work with.

Here's the remainder of the Cinema Series (as I see things now):

Cinema F-20 (this thread) with a stretched variant that's in the works. The stretched one (F-24) will play a little lower, but might need a more capable driver.

Cinema T-6 (coming very soon - fold is done, plans are done, multiple suitable drivers in hand, my initial beta was a fail, but the current refold's beta results are great) Tapped horn with an 8" or 10" driver, cabinet is 6 cubic feet, F3 of ~28 Hz, single 4X8 sheet of 1/2" plywood. Widths will vary based on the driver used, 11.75" internally is about the limit for an unbraced cabinet, no point in going wider, the aspect ratio of the throat (width/depth) gets too large IMO.

Cinema T-12 (coming soon, model is done, fold is sketched, scaled plans are started, drivers are in hand and need a proper home) Tapped horn, 12 cubic feet, F3 of 20 Hz, 10" or 12" drivers, two sheets of ply. Widths will also be varied on this one, and it might get a stretch, all of this depends on the results of the beta build.

Cinema T-16 (a little further out, model is done, fold is sketched, but I currently have no suitable drivers to test with, though I am working on that too...)
Tapped Horn, 16 cubic feet, F3 ~17 Hz, 15" drivers, less than 3 4X8 sheets of ply. As with the T-12, widths will be varied on this one, and it might also get a stretch, this all depends on the results.

My design goals for these?
Capable of at least 115 dB in a groundplane setting within 1/2 octave of F3.
No more than a 6 dB drop from 2 octaves above F3 to F3.

Can you comment on what will happen with your T-12/T-16/F20s etc when placed in a corner? Will the attainable flat frequency drop?
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post #115 of 1589
4/30/11 at 5:14am
Also, whats the sound quality difference between a Tapped horn and a FLH?
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post #116 of 1589
4/30/11 at 6:17am
Heeey Mikey lookin good!

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post #117 of 1589
4/30/11 at 6:24am
Quote:
Originally Posted by Maxjr View Post

What is the life expectancy of the driver in a horn? Is it expected to be less or significantly less than the same driver in a sealed or ported enclosure? I'm just thinking out loud here and wondering how the effects of the horn loading affect the driver's life.

I openned up 1973 Klipsch La Scala and 1978 Klipschorns and the drivers were immaculate and still sound great. No foam surrounds here though.
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post #118 of 1589
4/30/11 at 9:41am
Thread Starter 
Quote:
Originally Posted by Hawkson View Post

Can you comment on what will happen with your T-12/T-16/F20s etc when placed in a corner? Will the attainable flat frequency drop?

I feel like a broken record....
"Horn length sets the corner.

Placement and boundary loading might give you a Hz or two, but that is it. Horn length is the variable that drives the bus here.

Lower requires a longer horn. To go from 20 Hz to 10 Hz means doubling the length of the horn. That's the easy part. The hard part is finding a driver that can handle the added demands. There are not any single-driver solutions that I'm aware of."
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post #119 of 1589
4/30/11 at 9:50am
Thread Starter 
Quote:
Originally Posted by Hawkson View Post

Also, whats the sound quality difference between a Tapped horn and a FLH?

There is a difference. Some prefer tapped, some prefer front- or back-loaded horns.

For subs - which IMO, is all tapped horns as I currently design them are really good for, the sound of a PROPER driver in a PROPER tapped horn is hard to beat, when you weigh the remainder of the compromises. I've listened to both, but I am no golden ear. I listen to music and movies, not cables, op-amps, and capacitors...I've been known to play MP3s.....and vinyl is what my rain gear is made of....

I like a capable system, which requires a capable sub, I like my dynamics. I do listen at 100 dB or more on occasion.... Horns (tapped or otherwise) deliver the dynamics when I get them right.

I'm willing to sacrifice bandwidth to DC and go through the effort of a complex cabinet design and build to get the dynamics I desire in the rest of the bass spectrum out of fewer drivers and fewer watts of amplification.
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post #120 of 1589
4/30/11 at 10:34am
Thread Starter 
Quote:
Originally Posted by psgcdn View Post

I openned up 1973 Klipsch La Scala and 1978 Klipschorns and the drivers were immaculate and still sound great. No foam surrounds here though.

I opened up an old Karlson K15 cabinet I found when I bought my place a few years back. The Altec Biflex driver was still in fine shape. While not exactly a horn, it is a sort of bandpass, and loads both sides of the cone. That cabinet was older than I am, and judging by the stories, it had seen some use over the years.

Only driver I've killed in a horn thus far was a thermal failure, and was clearly a result of operator error....that pic is posted over in one of the Anarchy threads.

I've not torn a cone or ripped a surround yet. I've pushed the drivers fairly hard too. I'm not exactly setting out to kill drivers, but I do want to know where the limits are. Things typically sound bad or smell bad before they break, so I tend to turn it down before the bad stuff happens.
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