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-   -   A new FR product from Decware (http://www.diyaudio.com/forums/full-range/189818-new-fr-product-decware.html)

DaveCan 28th May 2011 11:45 AM

A new FR product from Decware
 
Well, Steve's at it again with a interesting take on a new small horn.

Seems like a large driver chamber is used to compress or filter the sound waves through a port hole before they proceed on down the horn path (At least from what has been shown). :cool:

Decware's Single Driver Horn

Scottmoose 28th May 2011 02:33 PM

It's a pretty little box to be sure. However, there's nothing new about this 'new DNA horn flare.' It's just a BVR, albeit with the driver chamber tapped into the horn a few inches from the throat. No big deal there, I've done a few designs like that myself over the past few years. There's also a lot of waffle, particularly in the 'audio paper' linked to from that page.

As an aside -I wonder if he's asked Ed Schilling whether he minds Steve using pictures of his Hornshoope Horn on the Decware site, and speaking of it in disparaging terms in order to help sell Steve's new product.

italynstylion 28th May 2011 02:50 PM

I call BS on usable response down to 20hz. I'm sure it will make noise down at 20hz but it wont be loud and it certainly wont be good.

DaveCan 28th May 2011 03:33 PM

I probably should have titled: "A new FR product from Decware" instead, sorry about that.. Mods can change it to that or something else if they want, as I can't anymore and it would make more sense for sure.. Nope, in case anyone wonders? I'm not affiliated with Decware other than owning an amp of theirs, but enjoy keeping up on Steve's new ideas and/or products..

An interesting driver right at that 5'' sweet spot perhaps? Didn't notice that one before as I mostly disregard the lower sens drivers when I'm looking at stuff..

Scottmoose 28th May 2011 03:44 PM

I'm sorry guys, but the more I read through that page, and what Decware are pleased to call the 'audio paper' attached to it, the more irritated I get. That material is deliberately contrived to fool the reader, mixing truth with half-truths & outright misinformation, all carefully presented to give the impression that new and advanced technology is being introduced. All hail the great Decware, who are here to save us silly little mortals from our folly!

OK, if that's the way they want to play it, if the moderators will indulge me, I shall spend a few posts here specifically pulling it apart, because frankly, I think somebody should.

Let's take the main page, linked to above (as of this date), and here too: initially. Decware's Single Driver Horn

The first thing we ought to note is the use of the term 'horn.' Decware are employing it in the same sense as I, and others do, i.e. a horn is a pipe that expands toward the terminus. It may be impedance matched down to it's cutoff frequency (which is determined by the length and the taper of the horn / tube), or it may not. Fair enough. We know where we stand. The presentation as if reducing a horn terminus is something unusual is a trifle over the top, but we'll let that one go, albeit with warning bells starting to sound.

Next up: flat frequency response.

Quote:

DNA's have flat frequency response - it's not tipped up or rolled off.
Right. Well, first thing to point out is that the Decware graph is 1/3 octave smoothed (unknown gating), so it looks even flatter than TB's own published plot (which isn't half bad, albeit already somewhat smoothed). More to the point, I can't see a combined response plot on that page. I can see the driver & terminus response plots, but not a combined one. Why not? Well, they might have forgotten. Or, they may be avoiding it because the combined response will inevitably look somewhat rougher than the driver & terminus outputs taken individually. Draw your own conclusions.

Scottmoose 28th May 2011 04:09 PM

Continuing from my previous post, let's take a gander at this 'Audio Paper.' Audiophile Home Theater This is where things start to get rather more interesting.

The first thing that strikes is that Decware are very concerned about the use of the term 'full-range' in relation to (particularly small) horns. In fact, this is repeatedly raised, in a critical sense, & it is stated that 'extended range' would be a better term.

No argument here; that's exactly what they are. However, the manner in which it is presented implies only Decware have appreciated this fact. In reality, this is linguistic semantics, as the term is typically applied to the 'full range' drive units employed in most small back-horns (which are really wideband / extended range units; a well known & rather obvious fact appreciated by the vast majority of people) rather than the cabinets themselves. Which begs the additional question -how many of these small horns Decware castigate for not being ~flat to 20Hz actually were designed to be, let alone claimed to be, in the first place? Not all that many.

What next? Well we next see remarks on 'standard horn theory' -true, to an extent, but presented in such a way as to give the impression that other people do not know what they are doing, as it is implied that they are unaware of the limitations of said approach.

In the process, we see remarks about the 'speed' of a [back] horn. Interesting. Because group delay in a bass horn is in fact typically rather poor compared to simpler boxes owing to the length of the flare path. The audibility of this or lack thereof depends on just how long the horn is, and the upper corner frequency (Fhm) of the design. Additional remarks about the efficiency of a back-horn in the same paragraph are accurate, but only insofar as they apply to the functional bandwidth of the horn. A back-horn, like any other back-load, is only useful / useable over a very restricted bandwidth. 250Hz - 300Hz is about as high as it is practical to run them before issues with separate sources & group delay result in undesireable coloration of the lower midband.

DaveCan 28th May 2011 04:10 PM

SM, no sorry's, worries needed etc, have at it :cool:.. Many here including myself are not as tech savvy with all that goes into cab design and math calculations etc.. It must sound pretty good though I would assume?, as he does have an open house for a DecFest each year for all that can attend to hear his products.. :cool: PS. Thanks to the Mods for the title change:), I should have written it that way in the first place.

Scottmoose 28th May 2011 04:22 PM

Fair enough. ;)

It might do -I haven't checked the design yet, so I won't offer any views on it yet. A lot of Steve's products do sound pretty decent to the best of my knowledge. It's the way they're often presented that really gets my back up.

Continuing from my last.

The paper proceeds to discuss the Lowther America Medallion horn (unspecified variation).

Quote:

This design also has a significant amount of dead air space down the back and in the bottom of the cabinet. Care must be taken to ensure these areas do not contain air or you'll have resonance issues to deal with. Best to fill them with sand.
Thanks Decware. How nice of you to provide construction advice on the Lowther Medallion horn in a paper advertising / trying to sell one of your own products. It would never have occured to anyone else, I'm sure, to fill a void with some form of mass-loading or absorbant material. It's also in really good taste, to discuss the product of a rival manufacturer in your own marketing literature.

Quote:

This enclosure is typical in that there is no dedicated air space behind the driver, only the horn flare itself.
Quite. It's a chamberless horn. Their point is?

Quote:

In this model the "throat" of the horn is not even clearly defined...
What on Earth is a 'clearly defined' horn throat? It either has one, or it doesn't. In the case of the Medallion, the throat is the sealed end of the horn directly above the drive unit. In the words of Clarkson, the hamster & Captain Slow, 'how hard can it be?'

Quote:

...we will hope that the magnet of the driver completely fills the round hole in the inner panel so that it becomes completely air tight otherwise the problems leaking air at this location would create are too numerous to list.
What patronising drivel is this? 'We will hope' indeed. Essentially, what they are saying is that 'we hope Lowther America build their cabinets well.' Another nice, tasteful thing to put in your own advertising literature. When it comes to DIYers of course, the build quality entirely depends on the individual, and applies to any cabinet, not just this one.

Bob Brines 28th May 2011 04:50 PM

+1 on the BS of 20Hz. What is presented is the terminus output hits F3 at ~20Hz and that the driver is ruler flat(!) 100-15kHz, implying that the SPEAKER has a bandwidth of 20-15kHz. However, as anyone who has ever combined the driver and terminus output knows, the combined trace --i.e. the real output -- will reach F3 somewhere between the two and have twice the slope.

Bob

Scottmoose 28th May 2011 05:08 PM

Oh +2 on that. Beautifully calculated to pull the wool over people's eyes though isn't it?

Continuing re this 'Audio Paper,' we've reached the Frugel-Horn (alas, Decware haven't bothered to spell the name correctly). I could be accused of bias here, so I'll state a few things up front.

-I was not heavily involved in the Mk1 Frugel-horn (which is the one referenced here), other than offering some views, and running some MathCAD simulations in Martin King's worksheets.

-I frankly was never over-enthusiastic about the Mk1 FH. For example, I always felt it was tuned too low / was too long for its size. The new FH3 is IMO a better balance of compromises -it is certainly not without its flaws, but I think the tradeoffs are better managed this time around.

-There are flaws in the text of the FH page. Those pages are due for a re-write. Time is the problem.

Now those are out of the way, back to the Decware paper.

Quote:

Another popular horn speaker, same size as the one above, using a 4 inch driver is calling itself a "full range" corner horn aka Frugal Horn.
Well, he's got us in the old linguistic sematics trap on that one, although it's disengenuous since the text on the FH site went on to discuss LF cut-off frequencies. Decware are using the term for 20Hz - 20KHz bandwidth, which is probably the most accurate use of the phrase, however, they are then deliberately using that to present those who have employed the term in a looser sense (for e.g. 'full-range driver') in a negative light.

Quote:

This design has a significant air space behind the driver and a clearly defined throat, albeit rather large, with the mouth of the horn exiting the rear of the enclosure.
Yes. The 'air-space' is generally known to designers as a low-pass filter chamber, although to read Decware's comments, one would think we hadn't a clue what it was ourselves. The throat area of the Mk1 Frugel-Horn as depicted in the Decware paper has a cross sectional area of 26.04cm^2, or 0.4x the Sd of the drive unit, i.e. rather [too] small, not 'rather large.'

Quote:

Again, they want you to put it in the corner of the room to re-enforce the bass, and since it's a horn and you put it in the corner, they call it a corner horn, which it is not.
The Frugel-Horn was designed to be placed in corners & uses the reflection boundary conditions to increase the effective terminus size & lower the frequency at which the horn is impedance matched down to. Perhaps Decware will be kind enough to explain why that is not a reasonable definition of a corner horn.

Quote:

With enclosure gain and room gain in some cases you can expect to have response down to 50 or 60Hz
Quite. That's because most of them are intended to have response down to around that frequency. What Decware's point is, other than that they are not designed to provide gain to 20Hz, I'm not quite sure. Note I am not defending such cabinets, or advocating them, or expressing personal preference. I am simply pointing out a fact Decware are deliberately ignoring.


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