I wish I could give you a solid method for all but it doesn't work that easy. When drivers get that close only real testing can make you hear what the differences really are.
It would not surprise me if the BMS can beat the 18Sound and RCF in SPL, but at what cost? If you have to invest 80$ more for the driver and an extra 750$ for an amp to deliver the extra dB's the price/SPL ratio gets a little odd. If you have the budget to spend, go for it... If you don't think twice...
Xmax is just another parameter like BL, moving mass, top plate thickness & voice coil height are others. They are all related and not one can be excluded. But still, all these parameters don't tell the whole story like temperature in relation to power and Re, system damping (I mean when a driver is mounted in a cab) and dynamic pwr comp values. Yes they can provide some idea about SPL but they sure wont tell you which one is preferred by the ear.
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Maybe -
Can you give me some guidance on what allowance you think is reasonable for the saw cuts.
Would you be cutting the mitres with the saw bench?
Also I take it that you are happy with a simple glued and screwed box and you are not rebating the sides?
This is one of the problems with providing a cut sheet, different people have different ideas, skills, and techniques for construction.
It would be very easy for instance to generate some DXF files to allow the sides to be rebated with a CNC Router.
That would probably be my choice!
Thanks for all the positive comments from everyone, I am very busy at the moment and it looks like that might be the case for at least another couple of months. However I am very happy to continue to develop these designs within the forum.
The current design is based on the inputs of many forum members and as such I am not really in a position to claim ownership of any part of it. I,m enjoying bringing all the different knowlege skills together.
m R g S r when you are ready to build let us know and we can start a new thread and get all the relevant information together in one place!
Martin, great job so far. I might finalise on one of the 18Sound drivers, given that my brother is meeting with the country dealer in two days at an Audio/Video exhibition at Mumbai.
Do you think that your design can be given a further boost by adding the "KEYSTONE" exit concept advocated by Art Welter (weltersys)? Thanks.
Looking through the Keystone thread the fundamental difference is the horn exits at a different angle to the driver. Art's design is based on extensive practical testing. The TH18 design is as yet untested - unless sombody else knows different! The performance is as yet not proven, apart from the extensive sims, and the basis of the layout on the SS15.
To take advantage of the keystone the exit would have to be out of what now is the base of the speaker. The keystone could then be cut into the panel. The shape would need to be developed by practical testing.
It would look similar to the sketch in this post.
http://www.diyaudio.com/forums/subwoofers/170771-single-sheet-th-challenge-75.html#post2511462
To take advantage of the keystone the exit would have to be out of what now is the base of the speaker. The keystone could then be cut into the panel. The shape would need to be developed by practical testing.
It would look similar to the sketch in this post.
http://www.diyaudio.com/forums/subwoofers/170771-single-sheet-th-challenge-75.html#post2511462
Thanks Martin. True, the TH18 is as yet untested. I could build a cab and report what I can hear. Need some guidelines for the K-slot. Not currently possessing any standard test equipment would not help the community move forward. This serious disadvantage not withstanding, I can proceed with building and testing by ear.
Moving the opening to the panel opposite the driver would do 2 things to the design: The horn path length would effectively be shorter and the way the cabs are oriented and stacked would not be desirable in typical PA venues/setups. So how do we deal with these issues?
Moving the opening to the panel opposite the driver would do 2 things to the design: The horn path length would effectively be shorter and the way the cabs are oriented and stacked would not be desirable in typical PA venues/setups. So how do we deal with these issues?
Hi. Would it be possible to try out the th18 design with a 15inch driver? I have a couple of 18 Sound 15NLW9400 that I got for trying in my t48, then SS15 and now you have me interested in the th18!
Any advantages/disadvantages to installing this driver (maybe on an adapter plate to allow 18s at a later date?)
Any advantages/disadvantages to installing this driver (maybe on an adapter plate to allow 18s at a later date?)
Basically that is not possible with this folding scheme.
Getting the tapers linear and smooth with the SS15 folding scheme is 'tricky' to say the least. Im just thankful that using parametric CAD I was able to adjust the box dimensions, rebuild the model and see the unfolded horn shape instantly. I then tweeked the angles and dimensions to optimise.
Within the confines of the CAD model I like to work to a accuracy of 0.1mm (so that you dont have to!)
The horn length can be increased by making the box taller. Any adjustment in the depth of the cabinet has a direct effect on the entire layout.
Either way I,m not really in a position to set out the cabinet again at the moment. After completing a 3 month contract I,ve been offered another 2 months of work that is keeping me far to busy.
Basically if you want to use the Keystone, best use the Keystone folding scheme.
Regards
Martin
The distance from the baffle board to the inside of the base is about 300mm minimum. The distance from the bafflle board to the internal divider is 68mm minimum You could probably rework the baffle if you have tools that would fit within these dimensions and you like a challenge.
My old B&D drill would fit for instance.If you have a 18" driver in mind for a replacement then you could make an adaptor plate. If you use 18mm timber the dip at 120hz might be a bit deeper.
The dip at 120hz is also effected by the inductance of the driver. As the actual inductance is probably bigger at this frequency than the quoted inductance of the driver the frequency response is probably smoother than the sim.
Check out this UK made driver - the Fane 18-15000 - it has a high Le value.
I dont think most of us have an amp big enough to drive this to its limits.
90V for Xmax - without adding in the compression factor
Attachments
Martin, I don't want to spoil your fun but maybe you should check this post about Fane and their strange tolerances in engineering.Check out this UK made driver - the Fane 18-15000 - it has a high Le value. I dont think most of us have an amp big enough to drive this to its limits. 90V for Xmax - without adding in the compression factor
never heard the end of that "story"
i have had 2 fane 15" studio 15L ,they were actualy quite good for semi pro stuf(talking 30 jrs back)
compared it with an rcf 15L 541 and it came close.
I own 2 Fane XB 15"
I gigged them for 10 years at 1200W each, before toasting them at my own birthday party
They have been reconed since, and are still in use. I also have 4 Fane 10" M Drivers, and 4 off 1" MD 2050 compression drivers.
My Brother has 4 of the older Colossus 15" 400W drivers. I have no complaints about Fane drivers.
Fane have been in business for 50 years and have had various ups and downs during that time. Currently they are closely associated with Precision Devices and in my opinion that puts them In a good position when developing new performance drivers
I gigged them for 10 years at 1200W each, before toasting them at my own birthday party
They have been reconed since, and are still in use. I also have 4 Fane 10" M Drivers, and 4 off 1" MD 2050 compression drivers.
My Brother has 4 of the older Colossus 15" 400W drivers. I have no complaints about Fane drivers.
Fane have been in business for 50 years and have had various ups and downs during that time. Currently they are closely associated with Precision Devices and in my opinion that puts them In a good position when developing new performance drivers
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Good idea
The distance from the baffle board to the inside of the base is about 300mm minimum. The distance from the bafflle board to the internal divider is 68mm minimum You could probably rework the baffle if you have tools that would fit within these dimensions and you like a challenge.
Or something like this http://headstartool.com/proimages/Screwdriver/D439-04210.jpg
Opposed to what thickness of timber? I thought 18mm was recommended.
Which B&C driver are you considering? Or did you mean BMS? According to what Djim pointed out a few pages back, I would narrow it down to the 18 Sound and RCF drivers, due to their superior motor/moving mass ratio. I'm thinking of ordering one of each (to test both) since both suppliers offer a 30 day money back guarantee.
m R g S r: what cabs have you heard or have experience with? Just curious what you'll be comparing these TH18's to
No individual cabinets really...but I'd say some of the best PA sound systems at various clubs throughout NYC. So I probably won't be happy with whatever I build, but ohh well.
I go out a lot and am always equally interested in the girls at the clubs as i am in the audio setups lol but to name a few
Phazon
Funktion One
GSA
alpha by Dynacord
SBS
and i was referring to the b&c 18tbx1000....
parts express says june 24th they are expecting more RCF drivers. I probably wouldn't have the cabinets completed by that date anyway, so maybe i'll just go ahead and order those...
I go out a lot and am always equally interested in the girls at the clubs as i am in the audio setups lol but to name a few
Phazon
Funktion One
GSA
alpha by Dynacord
SBS
and i was referring to the b&c 18tbx1000....
parts express says june 24th they are expecting more RCF drivers. I probably wouldn't have the cabinets completed by that date anyway, so maybe i'll just go ahead and order those...