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Author Topic: BillFitzmaurice DIY15" alleged to compete with Lab Sub????  (Read 49800 times)

Michael_Elliston¶

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With the increased sensitivity up high..
« Reply #10 on: November 02, 2004, 03:24:39 am »

I definatley would say that Bill never intended it to be a 'labhorn killer' , and i dont beleive it is.

What i think it is-is ,effective use of a 12" for guitar,bands etc.

Even if there was a labsub killer-it wouldnt 'kill' by much-only by using more expensive drivers! -It cant since the labhorn is an optimal design -alot of people dont realise this! Laughing

Cheers!
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Mark Seaton

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Re: BillFitzmaurice DIY15" alleged to compete with Lab Sub????
« Reply #11 on: November 02, 2004, 05:08:29 pm »

blades976 wrote on Sat, 30 October 2004 21:39

I hope someone can put the two side by side and give a fair and objective comparison some day.    



One of the guys who first built and measured the LAB sub sent Bill F. the proper response.  I was suspicious of the relatively low output from the single box, but I only could recall the response of multiple units, so I didn't object.  As before, these are drastically different animals.  Consider that the recession in the response around 40Hz is the first thing to pull up when placed near a boundary or another box.  Also it should be noted that Bill's graphs are plotted using a minimal 1/3rd Octave point of measurement, so most any significant peaks or dips are largely smoothed over.  The "Tuba 36" shown is an estimated prediction.  There is still no doubt that anyone with 2 LABs together will significantly out woof most competition.

Tuba 30 graphs

Cheers,
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Mark Seaton
Seaton Sound, Inc.
"Make no little plans; they have no magic to stir men's blood..." - Daniel H. Burnham

Peter Morris

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Re: BillFitzmaurice DIY15" alleged to compete with Lab Sub????
« Reply #12 on: November 03, 2004, 01:37:43 am »

Hi Mark,

FWIW I have played around with modelling the LAB design and variations thereof, and for a block of 6 I have trouble finding anything that will go any better. (that’s assuming the programs and assumptions I made were OK)

However in small numbers I think there are other designs would be more effective compromise.

Not to criticize Toms design in terms of performance but I always thought that the LAB sub as a DIY project was too complicated, and being optimised for a block of 4 to 6 was not what most DIYer’s needed. They need good performance with 1 or 2 boxes.  In addition having gone to all that trouble it would have been better to use a driver that could take a little more abuse, more forgiving suspension and a large voice-coil etc.

Which brings me to my next point – what about…… the LAB / Tom doing a 40 hz horn which is simpler in design and construction.

Something with about 7-8 ft of horn length, (ie 1/ 4 wave length of 40hz), usable to 200hz, and optimised to work in small numbers similar in concept to the Tuba or Punisher, but will truck pack and fit though a doorway.

When I analyse such designs in half space what I find is that you should be able to achieve an average of about 3-4 dB more in the 40 to 60 hz region and up to 10dB(!?) at 42hz than the LAB for a small number of boxes.

Sooooo what about it ????

Peter
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Michael_Elliston¶

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Re: BillFitzmaurice DIY15" alleged to compete with Lab Sub????
« Reply #13 on: November 03, 2004, 02:11:44 am »

Hi Peter
Thats Easy!

40hz-200hz
Simple Construction
Would have to be 12" for enough output.
Tcsounds Driver?


Im really keen on a high excursion driver with moderate-high power handling.

I have several designs from 2226-Tempest-lab12 ideas,
Cheers!index.php/fa/668/0/
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Mark Seaton

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Re: BillFitzmaurice DIY15" alleged to compete with Lab Sub????
« Reply #14 on: November 03, 2004, 09:30:32 am »

Peter wrote on Wed, 03 November 2004 00:37

Hi Mark,

FWIW I have played around with modelling the LAB design and variations thereof, and for a block of 6 I have trouble finding anything that will go any better. (that’s assuming the programs and assumptions I made were OK)

However in small numbers I think there are other designs would be more effective compromise.


Indeed, it appears even the BassTech7 only gets a little lower comparatively.  The one factor few of the modeling programs include is directivity.  That is the easiest way to get beyond the performance of multiple LABs.  Our upcoming bDeap-R looks to do very close to the sub 40Hz output of 4 LABs, where the directivity as seen in the bDeap-32 give even a pair equal or better performance than 4 LABs above 40Hz.  The response is certainly a lot smoother.  I will plan to post some measurements I have on our forum.

Quote:


Not to criticize Toms design in terms of performance but I always thought that the LAB sub as a DIY project was too complicated, and being optimised for a block of 4 to 6 was not what most DIYer’s needed. They need good performance with 1 or 2 boxes.  In addition having gone to all that trouble it would have been better to use a driver that could take a little more abuse, more forgiving suspension and a large voice-coil etc.


When the LAB sub project originated here, everyone was hyped up to build something with huge performance.  Of course most are used to hearing marketing specs, not real performance numbers.  "Enough" is often much less than one would think, or at least quite different.  The ability to "take more abuse" generally comes down to over designing, and more cost.  Make a LAB12 with only 7mm of Xmax and you would see people hearing the distortion onset much sooner and less probability of failures.  Who want's that?  Raising the low corner could help quite a bit with the excursion issue, and then we would probably start seeing more thermal failures as well as over-excursion from those not using a proper high pass.  Pick your poison.  So far as difficulty of construction, I personally see that a fair trade so far as price of entry for a FREE design. Rolling Eyes

Quote:


Which brings me to my next point – what about…… the LAB / Tom doing a 40 hz horn which is simpler in design and construction.

Something with about 7-8 ft of horn length, (ie 1/ 4 wave length of 40hz), usable to 200hz, and optimised to work in small numbers similar in concept to the Tuba or Punisher, but will truck pack and fit though a doorway.

When I analyse such designs in half space what I find is that you should be able to achieve an average of about 3-4 dB more in the 40 to 60 hz region and up to 10dB(!?) at 42hz than the LAB for a small number of boxes.

Sooooo what about it ????



Our bDeap design was intended to operate more optimally in smaller numbers through the use of boundaries or another adjacent box.  I would suspect Tom to first design a larger ABP type design targeting much higher output rather than the compact package.  Tom's real interest in the project was in keeping the design closer in line with modern design practices.  I think that was achieved and it is very clear that the LAB sub project has allerted and converted many people who previously would not have thought a bass horn was the preferred method of reproduction.  There are plenty here who are capable of designing a 40Hz bass horn of impressive performance.  It takes time, modeling, and some careful consideration.

What I suspect you will find is that we quickly approach scales of economy where manufacturers will be able to supply production products which will be similar in cost to rolling your own while offering a more known quantity.  I have heard of a few manufacturers looking to the LAB sub as a point of reference in performance, and I suspect we will see some interesting products in the near future.

In direct opposition to Bill F's beliefs, I feel our most intelligent path to better sound quality while keeping our average levels in check is to reach even lower.  High level output at 25Hz will radically change the pallate with which we and the artists have to work from.  Having actually done this outdoors on a smaller scale I am quite certain it is just a matter of time.  Response to below 40Hz is what most people find impressive in the pro-sound world.  There is justification for products offering hugely optimized performance over this range, as well as some reaching nearly the octave lower.

Cheers,
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Mark Seaton
Seaton Sound, Inc.
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Re: BillFitzmaurice DIY15" alleged to compete with Lab Sub????
« Reply #15 on: November 03, 2004, 06:31:53 pm »

I am working on a very compact horn subwoofer, which I am calling the "Crusher" horn, for the HL-10 woofer that should be good down to at least 55 Hz for a single box. I am trying to see how small of a mouth I can get away with, so that you have lots of little, easy to transport modules that can fit together for a huge, powerful bass stack, with the most output for the mouth area. My goal is to provide something I have heard mentioned on here a few times, where people wished there were a good horn subwoofer that was smaller and easier to transport, and that they would rather cart around 4 smaller subwoofers than two big LABs. Also, I am making sure it is relatively easy to build, with simple miter joints and easy-to-use openings into the rear chamber for access to the woofer. Small size is more important to me here than super low extension, though I won't settle for anything that won't reach 55 Hz. I expect to work more on it next week. If you're willing to wait a while, you should be rewarded. The goal is a sub that you can use anywhere from one per side (55Hz low frequency cutoff, -5dB) to 16 per side, and transport easily. I've already figured out how to fit over eight feet (97" in all) of horn behind my 15"x27" horn mouth (area: 405in^2) which makes up the entire front of the enclosure, which will be 34" deep. Unfortunately there won't be any handles but the box should be fairly small, and there will be casters on the rear so you just tip it up and roll it away. I'm making it a good deal smaller than the Punisher Horn, which uses a 12" Ciare woofer, so it will be even more attractive to people who might be considering the Punisher Horn. One limitation, however, is that the HL10 only handles 300w RMS instead of the Ciare 12.00SW's 1000w. The Punisher reportedly handled 1700w well. I might not have the chance for a while to build and test an actual Crusher horn unless someone is willing to buy and experiement with a HL-10 and report back to me how well the horn matches the simulation. The enclosure should be very relatively compact and easy to construct, especially with the lack of complex miter joints or routed holes and with the simplicity of the mounting of the access panel covers, so time and money invested should be very small.

One thing I need to know is what people want here. I have some concept drawings that are fairly advanced and about ready to go into Hornresp (the excellent program responsible for relative newbies like me breaking into the once-exclusive land of bass horn design). One thing I want to know is this: The current targeted bass cutoff is 55 Hz for a single box in half space. Would you have me try to go lower at the expense of sensitivity? Also, I'll have to see what Hornresp has to say, but the 97" horn of the Crusher is 1/4th the wavelength of 36 Hz. If the use of four or six of these boxes can get you down to 36 Hz, then that would be quite a thing to experience. However, it's been a while since I read up on horns, and I don't remember how mouth size affects the bass cutoff frequency. Guess I should do reading.

And if this turns out well, I intend to design the Super Crusher, designed around the LAB12, or perhaps the Adire DPL12 driver.
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John Chiara

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Re: BillFitzmaurice DIY15" alleged to compete with Lab Sub????
« Reply #16 on: November 03, 2004, 10:14:54 pm »

[quote title=Mark Seaton wrote on Wed, 03 November 2004 14:30][quote title=Peter wrote on Wed, 03 November 2004 00:37]Hi Mark,

 Our upcoming bDeap-R looks to do very close to the sub 40Hz output of 4 LABs, where the directivity as seen in the bDeap-32 give even a pair equal or better performance than 4 LABs above 40Hz.  The response is certainly a lot smoother.  I will plan to post some measurements I have on our forum.

Can you tell us a little more about this now?

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Michael_Elliston¶

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little lab 1 in 1pi
« Reply #17 on: November 04, 2004, 04:05:44 am »

Hi
BHFProfessional

Basically what your gona do(?),Is use a small driver with high Vd,on a CVbin like horn of longer length,punisher style folding.

Series of your statements and my comment.

Quote:

designed around the LAB12, or perhaps the Adire DPL12 driver.


Neither the Lab12 nor DPL12 are especially low distortion drivers,infact one could say they are just 'home theatre' quality.

Quote:

Would you have me try to go lower at the expense of sensitivity?

No. Imagine 600w RMS with music,inputted into the HL10.

Quote:

I'm making it a good deal smaller than the Punisher Horn, which uses a 12" Ciare woofer

How do you expect to make it alot smaller-when the path lengths should be relatively similar,with almost identical mouth areas.

The only difference is that the HL10 will require a longer path length..

Quote:

One limitation, however, is that the HL10 only handles 300w RMS instead of the Ciare 12.00SW's 1000w

1) Power ratings need to be of the same type eg 8hrs bandwidth limited pink noise for example

2)Power compression of either driver is NOT listed. For all we know,the Ciare could have 7db of power compression at 1kw.

-The actual difference in output wont be that great if linearity is about equal
Audible perhaps,but other factors will have more effect.

Quote:

The Punisher reportedly handled 1700w well

music signal,not sinewave for 15minutes

Quote:

(55Hz low frequency cutoff, -5dB)

That would probably be quite sufficient for most people.
1. Note that a box of this higher type F3,should have high bass also possible-its much more useful if it can effectively cover ALL the kick range up to 400hz perhaps.

2. Note that with a sealed rear chamber front loaded horn,the F3 appears to be where the Horn Flare rate cutoff has HIGH excursion ie unusable at high input-subsonic filter required,so the actual horn 'tune' is higher. Hornresp will show this effectively.

Note also that adding more boxes ie doubling mouth area-results in HIGHER FLATTER bass,not lower bass.(simulation)

Cheers!
Mike.e
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Re: BillFitzmaurice DIY15" alleged to compete with Lab Sub????
« Reply #18 on: November 04, 2004, 08:30:02 am »

Higher Flatter bass - you mean less-extended, less-deep bass? Or higher-level bass in terms of how far you can push things before they start blowing up? Or, perhaps you mean flatter bass, higher up in the horn's frequency range.

Also, as far as dimensions as compared to the punisher, I think my design has less internal wasted space, and the folding does not include any turns greater than 120 degrees, unlike the first 180 degree bend of the Punisher horn. Its mouth is only 15" wide compared to the Punisher's 18.5" wide mouth, and 27" high compared to the Punisher's 23.2" high mouth. The entire front of my enclosure is horn mouth, to make up for its smaller overall frontal size. The depth of my Crusher horn is 2" more than the Punisher. After the first turn of the horn, the Crusher looks a lot like a smaller Punisher, but a lot of horns start looking alike after that point anyway. The Crusher does not fire upwards into the horn throat as you can see in these plans (  http://www.speakerstore.nl/constructions/speakerstore/Punish er/punisher_bouwtekening.jpg), but downwards. Then the first section of horn follows that sort of slanted thingy up to where it can connect with the section that runs along the top. But a picture is wirth a thousand words, so I hope to be able to provide some sketches of my design here soon.
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Walt de Jong

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Re: BillFitzmaurice DIY15" alleged to compete with Lab Sub????
« Reply #19 on: November 04, 2004, 09:01:02 am »

Hello,

If you look at the construction of Ciare 12.00SW and Eminence HL10A I don not see a obvious reason why the Eminence would suffer less powercompression. The ciare has a very big magnet, a magnet gap hole and holes in the spider to make sure the generated heat can escape, therefore reducing powercompression. Also a 100mm coil has some advantage above the 63mm coil of the HL10A...

I would like to see a Hornresp or AJ sheet and graphs of your horn. I also played with the HL10A when I was looking for a driver for Punisher but the Caire 12.00SW always seemed to get louder en deeper in a same size cabinet. Well don't remember that exactly so let me see your results to compare.

Best regards,

Walt
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