My first front and rear horn loaded fullrange design: help needed from The Wise. - diyAudio
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Old 28th June 2007, 01:16 AM   #1
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Cool My first front and rear horn loaded fullrange design: help needed from The Wise.

Here I go at last!

Why bother with another project? Don't I have enough with so many unfinished projects already?
The answered is that I expect great things from this one: a front/rear horn loaded FR has a certain "magic" that is hard to resist.
If you don't want a big enclosure, don't read further...

It all began with the Autograph enclosure...a corner speaker. But I wanted a full frequency speaker that didn't need a corner to sound good, as not all rooms can accept those monsters.

After the 2:3 reduced Autograph replica (with AN super10 driver) defeated easilly my former Tannoy Definition 500 (I sold them), I began, with scottmoose's and AndrewT's invaluable help to develop the design that now occupies us.

The rear Autograph horn evolved to a very long horn, with a center block composed by 3 vertical foldings which then divide into two lateral blocks that flank the center block and which progresses front-back-front on the horizontal plane, to end on a big mouth " á la Kleinhorn" , but, as I said, divided in two.
The front horn is a reduced replica of Autograph's front horn.

I made a quick and dirthy version, halas, with a no-brand 3.5" midrange (not a true fulrange), that nevertheless sounds very good. HF lacks extension, midrange is beautifull, bass is wide and has surprising extension for such a little driver...bass is not very defined though, maybe because of the driver itself, maybe because of the long horn...I should buy a good 3.5" FR, but prefer to go straight to the developed version with a bigger one.
As you may know, soundstage is Wide and deep and instruments are very well placed and discrete.


[IMG]Click the image to open in full size.[/IMG]

I know it looks horrible (an uncompleted) , but believe me it sounds good.

The view from above should look like this:

[IMG]Click the image to open in full size.[/IMG]

This one explains how the wave goes (concentrate and you'll succeed ) . The enclosure front is 90cm *90cm.

[IMG]Click the image to open in full size.[/IMG]

Well, here I must seek help from The Wise to tune and fine-tune the enclosures to a decent frequency response, as I can't predict the behaviour of this enclosure with different FR drivers. As this enclosures can easilly be expanded to receive bigger drivers or even better a given enclosure could receive a bigger driver than it was intended, making a little mod and using a front horn suitable for its size
I am thinking a good 6.5 incher could do well. Or a 10incher on an 8" enclosure.

I am drawing detailed diagrams with autoCAD, which should be readable and modifiable by experts like you...
The only problem is that I don't know how to share these autoCAD files on a easy way.
Using autoCAD should allow for easy expansion and modification of the model, at your will, as it will facilitate the modeling for frequency response prediction.

We can discuss the pros and cons of this idea. Believe me, it is very easy to build!

Bare in mind that this was just a "first shot" model designed with pencil and paper only, as The Good Lord led me understand

I hope you like and feel inclined to cooperate.
These could be your last speakers

Bye,
M

Ooops ! I forgot the lateral view which should look like this

[IMG]Click the image to open in full size.[/IMG]
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Old 28th June 2007, 05:01 PM   #2
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More thoughts. Based on my experience.


1) as I said many times before, the climbing frequency response of most FR is well matched to the frequency enhancement patern of a front and rear horn enclosure, so, with a little tweaking of the box we can avoid any corrective circuit and end with a respectable curve with only one driver.

2) having horns for mid and low should sound better than only having horn for low or for mid. The horn acts as an acoustic amplifier, this enhances the driver's sensitivity, and makes feel the music as if you were using a magnifying lens; the music "jumps" to you, with great dynamic contrasts. This is lost for the part of the spectrum not using a horn, which could cause lack of coherence.

3) If you have a preferred 3.5"-4.5" FR you could use this enclosure but the driver will be too low. As I said, the enclosure can be easilly modded to make almost any combination, including putting the driver higher. This will lenghten the rear horn a bit.

4) There is enough room to make a bigger "compression chamber" if one feels the need for it, based on, I hope, future simulations.

Can anyone recommend an easy way to share the autoCAD files for you to analize the project?
Will google-documents be good?

Thanks
M
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Old 28th June 2007, 05:52 PM   #3
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>>> My first front and rear horn loaded fullrange design…

For your first front and rear horn, why did you decide upon such a simple design?

Actually, its probably a good idea to combine both front and rear loading. But I would look for a more elegant way to do it. I am curious to see how your project shapes up.
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Old 28th June 2007, 06:42 PM   #4
britbug is offline britbug  United States
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Hi,
MJKs website suggest an ability to simulate this might be coming at a later date. I certainly hope so, as I really find this a very alluring idea too.
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Old 29th June 2007, 04:01 AM   #5
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Hi Godzilla,

Quote:
Actually, its probably a good idea to combine both front and rear loading. But I would look for a more elegant way to do it.
By elegant do you mean good looking?

I only want real fullrange extension without a SW.
From what I'm hearing today (I swaped DACs) it is totally doable.

Hi Britbug ,

Quote:
MJKs website suggest an ability to simulate this might be coming at a later date. I certainly hope so, as I really find this a very alluring idea too.
Sorry, MJK?

Edit: OK, I got it

I will succeed at the end, trust me. I hope some of The Wise come around and help a little to shorten the "time to marketing"

I really find building square boxes too boring
(people seem to like building square boxes, strange, isn't it?)


Anyway, this enclosure can be made of 6mm MDF for the 3.5-4.5incher, as there is plenty of space to put reinforcements. I used spare plywood (9mm) from other projects for the side panel, with external reinforcement: very cheap.

I also consider, given the size of, say, an 8" version, to build blocks that could be assembled/disassembled with bolts.

Did you notice that bass and midrange/HF have a "coaxial" patern of emision? I chose a 90º angle for the bass horn mouth to match the front horn's firing angle

When you walk around the room you always have at least two "half-mouths" facing you: the soundstage never disapears and the "sweetspot" is not a spot but big area.
Ample soundstage + depth of image + great voices + dynamics= opera (sorry)


Glad that you replied, guys.
Cheers,
M
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Old 3rd July 2007, 03:28 AM   #6
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Hi again,

Quote:
MJKs website suggest an ability to simulate this might be coming at a later date.
In fact I only want to simulate the rear horn response, because I fear having TOO MUCH BASS. The behavior of the front horn is familiar to me. I also want to simulate how much midbass is enhanced.

I think that different driver sizes will need perhaps different rear horn design.
I think a good start will be a 6.5" driver and its corresponding enclosure. Smaller drivers' resonance is higher and that would make a dirty midbass response, I guess
For example, I hear that some midbass notes "shout" at me with my little driver and low bass notes are clean.

Have you heard a piano through a front/rear horn loaded FR??? (Kleinhorn-like, that is)
Response (attack) is fast; maybe a little delayed in my long horn, but that increases the sens of recording hall volume
As the mouth of the rear horn is big, the apparent sound source for bass frequencies of large bass instruments is also large. That, added to the natural bass harmonics and room reverberations, makes a lovely experience.

Silly me, I discovered that it was much easier to share diagrams than I thought. If anyone wants the original autoCAD files just send an email.

[IMG]Click the image to open in full size.[/IMG]

This is the center block; left is front. Follow the labyrinth and you will see that it "ends" on the left inferior corner, which in reality ends with two windows that feed each one the lateral foldings blocks, that are shown on the next diagram...

[IMG]Click the image to open in full size.[/IMG]

As my skills with CAD are minimal, I did not draw the width of the wood used.
You will have to consider it, of course, if you'd like to play with the boxes.

If you want to use a driver of 6.5", just multiply each dimension by 6.5/4 (the present enclosure accepts 3.5"-4.5" drivers). Dimensions can be modified as your imagination allows.

Edit: oops! The diagrams are too small! I will change them tomorrow. Sorry.
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Old 3rd July 2007, 04:06 AM   #7
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I forgot to mention that tomorrow I will make a diagram of the "unfolded" rear horn, which will help to simulate better.
Maybe I should try to simulate it myself...
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Old 3rd July 2007, 04:39 AM   #8
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"For example, I hear that some midbass notes "shout" at me with my little driver and low bass notes are clean."

Max, I certainly will not put myself in the wise group, but I have learned a few things about prototyping in the last couple of years. I wish you well on your project. It looks interesting. To comment on your quote above, have you fully braced and secured the cabinet, making it as solid as you would on a final build? Without doing that, you will never know whether a "shout" or honk, etc., is in the design or something with the cabinet itself.

Doug
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Old 3rd July 2007, 04:47 AM   #9
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Hi Doug

Thanks for your comment. Yes, I think I have put enough reinforcement. The first lateral folding run parallel walls so it is easy to use spare cut wood to glue it and make a stiff enclosure.

I re-read some of Scottmoose's comments on my other thread... My Second Tannoy Autograph enclosures

...and I think I will increase a lot the compression chamber of this enclosure to avoid midbass contamination. (I think he has not shown here because he knows I did not make my homework = studying the theory ).

Cheers,
M
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Old 4th July 2007, 02:45 AM   #10
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I deleted my previous images because they were too small.
These should be good.

[IMG]Click the image to open in full size.[/IMG]

Central block. Remember, these are good for little FR, like 3.5" to 4.5". You can "expand" or mod the enclosure as you wish.

[IMG]Click the image to open in full size.[/IMG]

Lateral panels that flank the central block. First folding goes from front to rear and second one the oposite way.

[IMG]Click the image to open in full size.[/IMG]

A view from the ceiling should look like this. I tried to mark potential compression chamber area. I also marked other front horn size for bigger drivers

[IMG]Click the image to open in full size.[/IMG]

Frontal aspect.

This is only a concept, but you get the idea...
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