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For modelling open baffle:  MathCad v Excel
For modelling open baffle:  MathCad v Excel
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Old 28th September 2006, 11:33 PM   #11
ScottG is offline ScottG  United States
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Quote:
Originally posted by MJK
MathCad vs. The Edge

The Edge models drivers on a wide variety of baffle shapes and predicts the influence of the baffle on the SPL response. It does both open and closed box baffles. It does not include T/S modeling of the driver so the drivers fs and 12 dB/octave roll-off will not be included in the plots. The interface is very good and the run times are extremely quick (I am envious). It is a great tool and I use it often to sanity check my own results.

MathCad is not as slick an interface but all you really need to do is enter numbers and let it calculate. It runs longer than the Edge and will not do anything other than rectangular baffles at this time. But it does include the driver's T/S low frequency performance and some ideal crossover behavior (think active crossovers) between multiple drives on the same baffle. The MathCad OB worksheets also include reflections from the room's floor and rear wall. If one assumes that the sound radiating to the side is minimal, then these reflections can be though of as the early reflections from the room. This is an incremental step beyond a free space solution, but I think it is in the right direction.

An Excellent unbiased "review" Martin! I'd also add that:

The Edge's strengths are usually related to a passband between say 80 Hz and ***up***. Here (as Martin has indicated), driver TS parameters can play a large part in sp-loss*. Typically though significant variations abound near the driver's fs. IF the driver's fs is a half octave or more below 80 Hz, (a 60 Hz value or less), and still within the operating passband (rather than well below it like perhaps a value less than 20 Hz), then the Edge just won't give anything close to an accurate representation at these lower freq.s, BUT from 80 Hz up the model should still be pretty good. The caveat here is a driver with a VERY high Qts (above 1) with an fs near 60 Hz or higher.

SO...

As long as you have a driver with:
1. an fs below 80 Hz, and
2. a qts below 1.

(or, have a highpass filter on the driver an octave or more above fs)

..THEN the Edge is pretty good (and is superior for freq.s above about 550 Hz), with the following 3 exceptions:

1. There is still the potenitial for "floor bounce" (which typically occurs around 200-500 Hz), and Martin's newer sheet's I believe address this in the model, and the Edge does not.

2. Lower in freq. you also have the effect of coupling the driver's lower freq. response to another boundry - the floor, IF the baffle is touching or very near the floor (i.e. not lifted off of the floor by any appreciable amount). Any gain here will not be reflected in the spl's represented by the Edge. (..and again I think Martin's newer models address this.)

3. Any other room effects will not be included in the Edges model. This includes room gain and freq. alteration due to room modes. I'm possitive Martin's newer model addresses room gain, but I'm not sure about modal deviations and loudspeaker placement in the room.. Martin?

This should highlight that you can still get a lot of value out of the Edge in many designs. And there is one other area that the Edge can also add significant value:

Sub designs with low fs (near 20 Hz) and low qts (below about .35) - a'la Linkwitz dipole subs. Here the Edge should give a good model (excepting issues #2 and #3 above), AND gives circuit compensation (eq) all within its "slick" gui interface.



*Note: a highpass filtered response an octave or more above the driver's fs will also likely reduce significant alterations in spl due to a high Qts.
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Old 29th September 2006, 12:17 AM   #12
MJK is offline MJK  United States
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ScottG,

Thanks for the feedback and comments.

Quote:
1. There is still the potenitial for "floor bounce" (which typically occurs around 200-500 Hz), and Martin's newer sheet's I believe address this in the model, and the Edge does not.
That is correct.

Quote:
2. Lower in freq. you also have the effect of coupling the driver's lower freq. response to another boundry - the floor, IF the baffle is touching or very near the floor (i.e. not lifted off of the floor by any appreciable amount). Any gain here will not be reflected in the spl's represented by the Edge. (..and again I think Martin's newer models address this.)
That is also correct.

Quote:
3. Any other room effects will not be included in the Edges model. This includes room gain and freq. alteration due to room modes. I'm possitive Martin's newer model addresses room gain, but I'm not sure about modal deviations and loudspeaker placement in the room.. Martin?
The model includes floor interaction/gain and rear wall reflection. I am not sure that this can be classifed as room gain. But you can move the baffle away from the wall into simulated free space but still maintaining the floor interaction. I am not sure that this is a complete characterization of room placement. Basically these OB worksheets, and all of the others, are intended to calculate the SPL response in front of the speaker baffle and the closer to on axis the more accurate the results. As you move away from the axis, say between 45 and 80 degrees, the accuracy is sacrificed somewhat.

In my opinion, the other nice feature of the OB worksheets is the ability to simulate a two way system using one or two woofers crossing over (active is assumed) to a full range or midrange driver with a variety of filter slopes and boosts applied to both drivers. This allows for the design of a complete open baffle system if you assume that any tweeter or super tweeter will radiate into 2 pi space in front of the baffle. Two pdf copies of the worksheets used to design the original and upgraded Lowther OB system are linked from that page on my site as examples of this design capability.

But getting back to the EDGE, I agree it is a very valuable piece of software and I use it frequently when I want to only study baffle geometry effects. When I step up to non rectangular baffles in my MathCad worksheets it wiill be invaluable in helping me check my equations and provide a sanity check for my intermediate results.

I am still working on OB and other dipole models, additional improvements and additional worksheets will come out as I progress and learn more.

Hope that helps,
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Old 29th September 2006, 03:01 AM   #13
rick57 is offline rick57
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Thanks all, I see attractions in each.

I just picked up MathCad 13 for $50; (when my 45> 845 amp is built) I’ll get the worksheets and The Edge.

Much preferring to design it myself (with good tools) . . if this was available 2-3 years ago, I wouldn’t have bought the Phoenix

(Whenever I asked a question at the Yahoo Group for Dipoles, if I got a response, it was invariably “why don’t do you the Orion”

DIY Dipole Software Design – the world gets better every year!

Cheers
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Old 29th September 2006, 06:15 PM   #14
ScottG is offline ScottG  United States
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Quote:
Originally posted by rick57


(Whenever I asked a question at the Yahoo Group for Dipoles, if I got a response, it was invariably “why don’t do you the Orion”


The Orion is certainly an excellent design (particularly for its size), but it does have numerous limitations that any given user/owner might not want to make a compromise for to accomidate it. Plus there isn't the satisfaction of actually creating your own loudspeaker.

The Edge you can start playing with now - its freeware:

http://www.tolvan.com/edge/

also check out his latest piece of freeware:

http://www.tolvan.com/xdir/

I absolutely love Tolvan's gui interface - its easy to work with and pleasing to the eye (..though of course thats just my subjective opinion).
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Old 1st October 2006, 11:33 AM   #15
rick57 is offline rick57
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Hi Scott

I’m * very curious when you say

> The Orion is certainly an excellent design (particularly for its size), but it does have numerous limitations that any given user/owner might not want to make a compromise for to accomidate it.

everyrthing is a compromise, but what Orion limitations or compromises are you thinking of, that might be overcome by a diy design (with either the Edge or MJK’s) eg ~ the ability:

With higher efficiency drivers to use a lower power or tube amp?
Or with similar watts to get higher max SPLs?
Avoid so many opamps?

other?

Rick
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Old 1st October 2006, 11:39 PM   #16
ScottG is offline ScottG  United States
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Quote:
Originally posted by rick57
Hi Scott

I’m * very curious when you say

> The Orion is certainly an excellent design (particularly for its size), but it does have numerous limitations that any given user/owner might not want to make a compromise for to accomidate it.

everyrthing is a compromise, but what Orion limitations or compromises are you thinking of, that might be overcome by a diy design (with either the Edge or MJK’s) eg ~ the ability:

With higher efficiency drivers to use a lower power or tube amp?
Or with similar watts to get higher max SPLs?
Avoid so many opamps?

other?

Rick
Hmm.. where to begin..

First the caveat - again it IS an excellent design, but..

(in the "negative" for perspective..):

1. No Horn High Eff. Loudspeaker enthusiast would ever trade the positive qualities of a *good* horn design for the Orion. In this respect then its a matter of extreme dynamics, physical/visceral sensation, a subjective sense of "speed", and *very* low non-linear distortion for a given input level. (..and note that I'm not particularly a Horn Loudspeaker enthusiast - I recognize both possitive AND negative attributes, and so far could not reconcile with those negative attributes.)

2. No Low mass driver enthusiast would ever trade the positive qualities of a good low mass (for a given sd) driver loudspeaker for the Orion. Delicacy, Nuance, Texture, and a subjective sense of speed COUPLED with "ease" - are all qualities that abound with such a design and the Orion will not have this quality (..at least from the upper midrange - up). Perhaps a more "holistic" description of such a speaker would be "Organic" and a speaker that "breathes". Oddly, damping factor plays a LARGE roll here with overall quality - IF the pairing amplifier has a low output impeadance for most of the operating passband then such speakers do NOT sound their best - often becomming "thin" "flat" "dimensionless" "2d"..etc.. Again, any true enthusiast here would be using an amplifier with a fairly high output impeadance and would of course suffer from some "bloat"/gain at driver resonance to obtain the best qualities of a low mass driver over *most* of the operating passband.

3. Its *likely* that no flea power amp enthusiast would trade the sound quality of "minimalism" for the "complexity" of the Orion. It isn't so much a matter of solid-state vs. tubes here, but rather parts count and component count. MOST of these enthusiasts realize that the greater the parts count, some how the worse the sound.. AND that the lesser the parts count, the more obvious each part counts towards that component's audible character. Here you have 3 "problemes" with the Orion:

A. the active crossover - it may be in the correct "order" (i.e. "ahead" of the amplifier), but its *full* of parts;

B. the requirement for multiple amps and the complexity associated with altered tonal behaviour with DIFFERENT amps in different "locations" (..i.e. perhaps a massive solid state amp for the bass and something else for the mids, and perhaps something else as well for the treble - may require a LOT of experimentation to get "right" tonally from an "integrated" perspective); and of course,

C. the requirement for at least one amp to not BE a "flea" amp (..i.e. the bass amp which will require plenty of "head-room").

.........................

Well then, thats just a few reasons beyond DIY'ing your own design why you might not be able to accept the Orion.
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Old 2nd October 2006, 01:26 AM   #17
johninCR is offline johninCR  United States
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In addition, to Scott's analysis is a complaint I've heard directly from Orion owners (also a more objective vs subjective item), is that they are fairly limited in bass dynamics as would be expected from only a pair of 10s per side in OB with such a small front/rear wave distance differential.
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Old 2nd October 2006, 01:42 PM   #18
rick57 is offline rick57
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Hi Scott


> No Horn High Eff. Loudspeaker enthusiast would ever

99/ 100 probably. But FWIW an Exemplar owner now prefers the Orion.


Low mass driver
Hmm, in a two way active, maybe a Low mass driver with amp in a low damping factor ratio, could give breathing etc above about say 250 hz; then a amp in a low damping factor ratio below that nice tight bass


BTW, Linkwitz insists that the Orion and its predecessor use the same amps in all frequency bands.

But my $64k question; could a diy design (with either the Edge or MJK’s) for open baffle ~ with decent drivers of course ~ give the smooth response of a (heavily XOd) Orion??

GTG (SHMBO)

Cheers
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Old 2nd October 2006, 07:50 PM   #19
ScottG is offline ScottG  United States
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Quote:
Originally posted by rick57
Hi Scott


> No Horn High Eff. Loudspeaker enthusiast would ever

99/ 100 probably. But FWIW an Exemplar owner now prefers the Orion.


Low mass driver
Hmm, in a two way active, maybe a Low mass driver with amp in a low damping factor ratio, could give breathing etc above about say 250 hz; then a amp in a low damping factor ratio below that nice tight bass


BTW, Linkwitz insists that the Orion and its predecessor use the same amps in all frequency bands.

But my $64k question; could a diy design (with either the Edge or MJK’s) for open baffle ~ with decent drivers of course ~ give the smooth response of a (heavily XOd) Orion??

GTG (SHMBO)

Cheers
The Exemplar (if I'm thinking of the correct loudspeaker) does not have what I'd consider the same physical sensation as the type of horn high eff. loudspeaker I was referring to. I think this is directly related to using the midbass 15 inch driver over such a wide bandwidth. Chances are such a driver just won't have the "force" neccesary in the midrange. (..also, comparitivly speaking, the Exemplar is a VERY small speaker trying to do almost full range duty - and there lies compromise.) I'd also guess that the owner that "switched" from the Exemplar to the Orion was never *totally* satisfied with the Exemplar, and likely went through several loudspeakers before currently "stopping" at the Orion. I'd also bet that there are some aspects of the Orion that the owner thinks, (perhaps only subconciously), are still lacking. In otherwords this is not what I'd call a true "enthusiast".. Instead think of Magnetar as a horn/High Eff. *true* "enthusiast".


The problem with the premis of different driver types and dampening is the passband for each. Remember that the midrange effectivly extends to about 80 Hz - NOT 250 Hz. As a result there could well be discontinuity with a lot of recordings if it doesn't extend down to 80 Hz for "similar" mass drivers. (..as a general rule - think of doubling mass for a given sd for each octave lower in freq. Of course this puts a "strain" on drivers around 2 kHz and 200 Hz to meet this general rule.)

SL uses the LM3886 - (a very good op-amp) for all drivers I believe. However dampening factor is very high with this amp and as a result its better for use with higer mass lower eff. drivers (all else equal) - and that's what the Orion uses. I could be wrong, but I'd bet he uses more than one LM3886 for the dipole woofers.

I don't think either MJK's mathcad sheets or the Edge *alone* will get you where you want to be for a FULL system design. IMO you'll also need measurement AND crossover modeling for a true full range loudspeaker (..or something like the DEQX crossover).

Another aspect is size - SL has the Orion "pinned" down to a very small form factor for a full range design. It would be EXTREMELY difficult to have a similar design without signifiant flaws that approached the Orion at the Orion's dimensions and had the benefits of those other types of designs I've mentioned previously. (..and of course the real limiting factor is bass extension vs. size - chances are to get a simlar size and extension would probably mean designing something very similar to the Orion). On the other hand IF you want those other attributes and are willing to deal with a larger loudspeaker (probably MUCH larger) - then sure, it is *possible* that you could make something better than the Orion.
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Old 4th October 2006, 03:02 PM   #20
rick57 is offline rick57
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Hi Scott

> I don't think either MJK's mathcad sheets or the Edge *alone* will get you where you want to be for a FULL system design. IMO you'll also need measurement AND crossover modeling for a true full range loudspeaker (..or something like the DEQX crossover).

I agree with a 90% of that – but can’t afford a DEQX.
Your thoughts on how a Behringer DCX 2496 http://www.duffroomcorrection.com/wi...inger_DCX_2496 (which can handle instructions from SoundEasy www.interdomain.net.au/~bodzio/ ) would fare?

> SL has the Orion "pinned" down to a very small form factor for a full range design.
Yes, I can just very recently afford to go bigger

> On the other hand IF you want those other attributes and are willing to deal with a larger loudspeaker (probably MUCH larger) - then sure, it is *possible* that you could make something better than the Orion.

I was intending to aesthetically cheat, by doing the baffles (or all bar the part that mounts the drivers) in eg Perspex.

Cheers

Richard
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