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Message started by Valiant on 11/09/07 at 14:34:07

Title: Mr Valiant's Half Imperial
Post by Valiant on 11/09/07 at 14:34:07

Greetings guy's, I'm going to keep this message brief, as I
tried to send a message earlier that seems have got lost in cyberspace :(.

With the sheets of board left over from mine and Jake's metric Imperial, I've
started building a 'half Imperial' for my son, who is currently studying music
and plays guitar and bass guitar.

So, I'll call it quits for now. Disappointed that my original post appears to have gone
nowhere, but I'll post more details and pics if all is well.

Hi to you all, :)

Gazza (Valiant).

Title: Re: Mr Valiant's Half Imperial
Post by Valiant on 11/18/07 at 14:13:10

Here's a pic of the speaker box... I've set it up so as I can change the front
panel to try a variety of drivers. Initial set up will be 4, 8" woofers I've
had lying around for  a little while now.
Gaz

Title: Re: Mr Valiant's Half Imperial
Post by Valiant on 11/20/07 at 22:40:06

Dad popped over on Monday and with a couple of hours work,
here's the result... :)

Title: Re: Mr Valiant's Half Imperial
Post by Valiant on 11/20/07 at 23:04:15

I haven't yet painted the outside of the cabinet and finished all the trimmings,
but there are only a few more hours work left to do. Fired her up of course and had
a quick listen, not too loud ;). The Half Imperial still goes deep, plenty of
twenty hertz stuff vibrating various items on the patio, even more at thirty hertz.
Musically, she has a good spread across the audio range. It would be interesting
to do a few tests in that department. Vocals are clear, and even cymbals are
quite audible, though I feel the SPL is dropping off around 8000Htz or so.

But enough of the tech talk for now. My only dissapointment is that I didn't build
a stereo pair. Sizewise alone, they are a more civilised version of the 'Full Imperial',
and still deliver (though at a more reduced SPL). As they are, they will be
suitable for my son's guitar, or for that matter any stage application. I'm looking forward
to trying different drivers. The current 8's are garden variety cheapies, better
ones are on the cards. At a pinch, I may be able to squeeze in 4 x 10"s, possibly
2 x 12"s. We shall see ;D.

Until then, here's another pic, with a certain item to give it some scale.

Cheers,

Gaz

Title: Re: Mr Valiant's Half Imperial
Post by Young_SC on 11/20/07 at 23:54:45

Hi Gaz,

That's a good looking speaker.  

You've got more guts than me, I haven't got the experience to build stuff from theory.  I rely on tried and tested plans to copy.

When it comes to finishing the rest of the cabinet, consider keeping it a light colour.  There is a nice contrast with the black front and horn mouth against the lighter colour of the outer cabinet.

Simon

Title: Re: Mr Valiant's Half Imperial
Post by Chris K on 11/21/07 at 18:18:26

VERY COOL!
Explain please how it is half?
All heights different in the pic with the beer bottle. And it seems much narrower. Mouth is not square but what are the mouth dimensions? Or is it indeed all the same just cut in half down the front view?

Title: Re: Mr Valiant's Half Imperial
Post by 60_and_up on 11/22/07 at 01:55:06

mines smaller  ;D


http://video.tinypic.com/player.php?v=3zjjomv

Title: Re: Mr Valiant's Half Imperial
Post by Valiant on 11/22/07 at 03:20:28

Hey 60, I checked out your totally cool clip a while back and I'm still laughing  ;D ;D ;D
I've just shown it to the family and they reckon it's totally cool too! From the looks it's about 1:4 or 1:5 scale? I'm tempted to do the same, maybe a 1:10 scale and fit a AM/FM radio in there, just for fun. Maybe we can have a competition to see who can build the smallest, functional,to scale Imperial ;)

Hey Chris, allowing for the fact that I was using 18mm chip instead of the preferred 3/4" ply, I cut the speaker chamber braces to size, and used a ratio of 18.5/19 x 'Decware Plan' to give the appropiate horn dimensions.

This gives me a speaker 7/8" shorter and 3/8" shallower than the plan. The width of the box is a whisker less than half the true Imperial.

A single jarrah wood brace secures the rear of the horn, and is a nice touch too. Eventually I would like to use a fine piece of jarrah ply for the 'speaker panel'. This is one item that will get extra reinforcement in the shape of some angle iron braces. The speaker panel is all holes and can only benefit with some extra stiffness.

I agree Simon that a lighter colour on the outside of the box would be a good contrast to the dark interior, but I'll probably finish the outside with the black hammer finish, if only to match my existing speakers and in keeping with a common theme.

Looking forward to seeing your SO. Looking good.

For those who have forgot, here is a pic of my original Imperials...

Title: Re: Mr Valiant's Half Imperial
Post by Valiant on 11/24/07 at 09:59:51

STOP PRESS: I just want to make it totally clear that my half Imperial is
in no way comparable to the full Imperial. Playing some tunes through
the 1/2 Imp which sound great, in no way compare with the IMPERIAL which
shook every item in my house, and the neighbours too.

The half Imperial as built with the 4, 8 inch woofers offers good extended
midrange and nice bass, but I'm not kidding myself, and don't you either.

Still, an exellent speaker none the less. More pics and details to follow...

Cheers

Gaz
:)

Title: Re: Mr Valiant's Half Imperial
Post by Gexter on 11/24/07 at 20:09:17

Hey buddy!
I wonder if the FS was lower it would play lower. It would be interesting to try a single 12 with a Fs lower than 30.
John in C.R. did some sims with a half IMP as a sub it was looking favorable. A low Fs full range 12 always interested me in a half Imp.



Title: Re: Mr Valiant's Half Imperial
Post by Valiant on 11/25/07 at 00:39:52

Hiya Guy,
Guess what I have sitting in the shed? An old 12 inch sub that Jake passed
onto me a few years back. With the replaceable front panel, I'm going to
enjoy this Imperial to the max.  8-)

Gaz.

Title: Re: Mr Valiant's Half Imperial
Post by Valiant on 12/10/07 at 13:44:35

And for now, here is the finished product. :D
Oh, I picked up a sheet of Jarrah veneer that is big enough to cut a
panel for the 4 x 8's and (this is what lights my candle), a front panel
for 1 full sized Imperial., plus a few lengths of 2x3 Jarrah for the back
braces. In other words, the full sized Imperials are a goer, though it maybe
sometime before I start cutting wood.

I'm considering the following, a 15inch woofer, sandwiched by 4, 8 or 10 inch
drivers. Hmmm ;) Like I said in an earlier post, I'll check out various drivers
in the half Imperial and see what delivers.

"Dank's" article 'Interesting twist for an Imperial' gives us some idea
as to what can be achieved (definately worth another read). The Decware Imperial
concept of using mismatched 15" drivers in the cabinet may find its nirvana in the
not only mismatched, but mis-sized driver scenario.

Of course, the immeadiate queary from wife and friends is...'where are you
going to put them?' Ahhh, leave the fine print till later huh. You guys know what I mean.      

Title: Re: Mr Valiant's Half Imperial
Post by Valiant on 12/10/07 at 13:55:42

One more pic, just because I think it is cool. The array speaker on the
left is my own design, 6 x 5" drivers and 4 x 1" Vifa tweeters. The stereo
set up is as you see, with one of my arrays doing the right channel, with the balance
slightly favouring the right. The Half Imperial and array are hooked up via a
2 way active crossover (~3500Htz), the array woofers are not hooked up, the tweeters
supplying the +3500Htz signal. Sounds okay. The little array holds it's own on the
right.

Cheers,

Gaz.

Title: Re: Mr Valiant's Half Imperial
Post by Valiant on 12/18/07 at 13:14:36

Oh okay, here is one more pic of my woofer.
Actually it is my daughter's woofer which I seem
to have adopted. Not a bad lookin dog for a
chihuahau, at least that is what my daughter
was told when her boyfriend bought him.

Title: Re: Mr Valiant's Half Imperial
Post by 60_and_up on 12/19/07 at 02:43:15

looks fun :D


Title: Re: Mr Valiant's Half Imperial
Post by Young_SC on 12/19/07 at 07:49:09

You're leaps and bounds ahead of me.  I haven't done that much more than what I've photographed.

Too busy at work which is leaving me tired and unmotivated to go out to the garage.

Let me know what excuses you came up with regarding placement of the horns :)

Title: Re: Mr Valiant's Half Imperial
Post by Valiant on 12/19/07 at 12:26:59

It's all good Simon. Building the half Imperial was a cinch compared to the
                       IMPERIAL.
It's just so darn big, not the sort of thing us amateurs can slap together
in couple of hours, or do a little bit and then put the item back in the
drawer till next week. It took me months to complete two Imperials,
mainly because I would have to organise a spare pair of hands for the
heavy bits.

Where am I going to put the horn? Hey buddy, notice it's still on the patio
(with the woofers  :D)

Cheers

Gaz

Title: Re: Mr Valiant's Half Imperial
Post by Henry on 07/03/10 at 07:56:31

Now that I have seen your work, it can be done with the expectant
results. Obviously, I'm not expecting any smaller scale designImps to
to knock stuff off shelves in the neighbor's house next door, but should
sound beautiful and full non-the-less ;)

By the way, did you document your effort , so it can be refurred to help
someone else scale their Imperial design down :-[

Title: Re: Mr Valiant's Half Imperial
Post by Valiant on 07/09/10 at 14:59:53

Hi Henry,
If you want some more data about the Half Imperial, I will gladly send the numbers. As I am always quick to point out, the Half Imperial (and the full Imperials for that matter), where built on the cheap, I can only imagine just how they would sound using premium materials. Just wondering if I'm in breach of rules if I 'publish' the measurements ??? which after all are not exactly 'half', but certain elements are Steve's design. i.e. buy Steve's plans and what comes off the saw is yours  :)
Gaz

Title: Re: Mr Valiant's Half Imperial
Post by Henry on 07/14/10 at 21:21:22

Your modifications of Steve's plans for your half scale Imps design are a helpful reference. I'm sure he wouldn't mind....But will ask first before moving forward on my request for help in this area ;)

Title: Re: Mr Valiant's Half Imperial
Post by Valiant on 07/15/10 at 04:31:26

It would be helpful if you purchased Steve's plans. The various angles, shape and size of the horn (but ~1/2 width) are identical to the Full Imperial. My major detour being the use of 18mm particle board, the heavy stuff used for flooring. I think I've got the 18mm/19mm original ply conversion sorted. This is where I can be of some help. Just need to run a tape measure to give you overall h x w x d type stuff.
Gaz

Title: Re: Mr Valiant's Half Imperial
Post by Henry on 07/15/10 at 20:55:14

That'll work....I get the plans and then we can go from there, Thanks!

Title: Re: Mr Valiant's Half Imperial
Post by Valiant on 07/18/10 at 12:56:02

I'll get the tape maeasure ready!

Title: Re: Mr Valiant's Half Imperial
Post by Henry on 08/02/10 at 11:26:25

Got the plans. Been comparing the inner baffle section of the '59-'63
plan to Decware's modified version....The modified version has a
more open inner chamber I noticed.

Title: Re: Mr Valiant's Half Imperial
Post by Valiant on 08/11/10 at 11:47:09

Hiya Henry,
I'll get back to you shortly. Firstly though, what grade (thickness) wood are you planning on using. That is the major concern when figuring out height and depth issues. As you see, the Imperial plans are for 3/4" (19mm) ply.
Gaz

Title: Re: Mr Valiant's Half Imperial
Post by Henry on 08/12/10 at 01:28:35

I'm staying with the 3/4"(19mm) plans :)

Title: Re: Mr Valiant's Half Imperial
Post by Valiant on 08/14/10 at 04:24:52

Then thats easy. For height and depth, you cut the wood as per Steve's plans. The width is the only modifier, which in my case, is a whisker less than half. (Can get exact measurement). I guess the only other factors which might alter tonality and response is the amount and type of filler you put in the speaker chamber - of which I used very little. One thing I never got around to doing was stiffening the front face of the speaker baffle. I figure that may help sound even better = less extraneous vibrations imparted to the drivers.
As a starter, measure out (even using newspaper) a fullsize template of the front face of the 1/2 Imperial approx 6ft tall x 1.5ft wide to give you a good idea of what to expect. Will it fit in your room, ht, back seat of your vehicle  ;D

Title: Re: Mr Valiant's Half Imperial
Post by Henry on 08/14/10 at 08:21:47

Definately, not the backseat of a vehicle....Except a motorhome!
Bedroom is out of the question. A large recreation room will work
as a sound space.
Did you scale down the inside baffle chamber, or did it become part
of the upper chamber space where the throat begins?

Title: Re: Mr Valiant's Half Imperial
Post by Valiant on 08/16/10 at 14:48:37

The baffle chamber size and shape are exact to the plans, other than the width of course. The baffle chamber, being one of the trickiest components, may well be one of the first pieces to build.
By the way, what do you reckon of the full sized Imperial plans? When I finally got my head around what I was seeing, I was amazed. I printed out the plans on A3 paper, in colour. Made things much clearer. Errr, my smilies don't seem to be working?

Title: Re: Mr Valiant's Half Imperial
Post by Henry on 08/18/10 at 01:28:10

I gave up using smilies for a while.
Anyway, I blew up portions of the plans to see what the
various messurements were and figuring the gap width of
the inner chamber vent.....I think it's one inch it looks like.

Title: Re: Mr Valiant's Half Imperial
Post by Valiant on 09/01/10 at 02:37:56

Correct! The next one is two inch, then shortly after that, it gets bloody big! If you where to build the 'half' Imperial, what driver/s where you intending to - err - drive.

Title: Re: Mr Valiant's Half Imperial
Post by Henry on 09/01/10 at 10:25:07

12" Electrovoice Wolverine(s) Co-Axial(s).
I have a pair of 8" Wolverine Co-Axials That
may sound impressive in such a cabinet design.

Title: Re: Mr Valiant's Half Imperial
Post by Valiant on 09/08/10 at 14:26:45

The 12" Electrovoice Wolverine speakers should be great, in which case you may end up building an Imperial about 2 foot wide.
Or, you could build two 1/2 Imperials with an 8" + 12" in each cabinet!
You've got me thinking! I've got a pair of twelves (or is it tens) still in the boxes, hmmm, maybe I could try 2 x 8" +  12" + the Vifa tweeter. As I described in my build, the baffle plate (what the speakers are fixed to), is removable and interchangeable.
If you are concerned about using different sized speakers in the same Imperial, don't be. Check out some of the earlier posts, you'll see some wildly differing differing drivers in the same box.
The design of the Imperial almost makes this mandatory and of course, the original texts where based around this delta.
Me thinks I might be buying a piece of board next week, time I had another play.
Gaz

Title: Re: Mr Valiant's Half Imperial
Post by JimP on 10/27/10 at 21:58:03

Hi Guys,

I have built 2 half-Imperials and use them for live music.  I simply cut the plans in half, taking into account the thickness of the material I used (3/4").  I have used the speakers separately as 2 mains on either side of our stage, or as one speaker(both halves placed next to each other).  When used as one, they basically act like one full size Imperial, which was my intention (I have a second full size imperial also).  As individuals, the half-imperials sound good but don't have the low bass power of the full.  I loaded all my speakers with 15" Dayton Pro speakers and use a horn for the upper ranges.

Just an FYI if it helps you out.  Good luck and enjoy your imperials, whichever configuration you build!

Jim P

Title: Re: Mr Valiant's Half Imperial
Post by Henry on 10/28/10 at 04:19:06

Thank you for the encouragement JimP :)

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