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MesajScris: Mar Noi 22, 2005 10:06 am 
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@James: Have you actually seen inside one of those Noize Control boxes? - the only info I can find on them shows a grille in the horn, so cannot tell what is happening in the throat. I also note that their info does not include response and polar plots....


The top / mid flares on the NCA Tmt were designed for 50 x 40 to allow the tight stacking of the trapezoidal boxes. Having FAFFED about with bits of wood and " the right hand width " distance to get the right dispersion when using F1 res stuff I can`t see why they went trapezoid in the first place !

I could take a foto for you of the TMT mid flare but I can`t give you the dimensions . It uses a small throat is all I can tell you at the mo`..! Raey is pretty elusive when it comes to design stuff ( rightly so if your selling the boxes ! but I can get some info out of him). It uses the rcf l10/750yk ( or a fane version which I`ll find out).

Plots and response charts are on the way but some new drivers are being tested at the mo ( neo ones to lighten the boxes for flying) so not sure which ones they`ll paste up.

And to stick my two pennies worth in.....

The f1 folded horn on the re4 / res 5 have phase bungs and the res 2 doesn`t. Just a point that the res 2 uses a 15" on a short fold with the driver reversed to keep the vc cool... A practical easy to build box which IMO is the route I`d be taking..? Only gripe I have with them is the x-over to the 218 always sounds "confused"? ( best description I can think of ..it`s not wrong , jusst not totaly right?). The all in one mid / high moulding is another winner in design but I should imagine the tooling costs are horriffic ....

So I`d go for something similiar to the res2 for the bass and try to combine that with a 50 x 40 flared mid/ top section to keep it simple and arrayable?

I`m no cad wizzard tho` so I`ll just grumble from the edges !

.p.

edit...The Fane 10" is a crescendo 10m


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 Subiectul mesajului:
MesajScris: Mar Noi 22, 2005 3:35 pm 
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phil, how much can noise control source the 18 sound 6nd410 for? i have been eyeing up the spec and as graeme points out, it is a right little beastie! sensitivity is far more useful than the p-audio (sorry nexus!), although i'm still keen on using the sn series 12s as they are so damn cheap. yes, the 12b is more powerful than the mb, it will have to work very hard to keep up with the high mid section whatever, so you are probably right about modelling more for this driver.

this choice of drivers will push the price up again, using a timber hf horn will drop it a bit. we haven't discussed budget much, obviously the discussion is complicated by the multiple currencies and suppliers/importers involved. bearing in mind this cab is designed to be used with at least 2 per stack we may well have to make a few compromises in order to make it affordable. does anyone have a maximum in mind? i would like to aim for around £300 per cab on the drivers, and i don't think we'll get that much for much less.

reverse loading the 12s for voice coil cooling is a very good idea, i shall have a jiggle round on my sketches and see if i can make that fit in a logical way. heat sinking the 6"/8" will be good for mega power handling and ludicrous output plus increased driver longevity, could be worth the (significant) hassle, especially to keep those fancy neo magnets cool!

james.


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MesajScris: Mar Noi 22, 2005 4:05 pm 
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james, ind.st scrie:
sensitivity is far more useful than the p-audio (sorry nexus!)


Absolutely no problem.

I was designing my owh wide dispersion box and I was modeling the B&C 8PE21 atrough I am distribuitor for Selenium & P-audio.

I just could not find a equivalent driver from p-audio or Selenium.

I think 300 Pounds / 500Euro / 600$ for the drivers/box would be ok

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MesajScris: Mar Noi 22, 2005 4:53 pm 
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i've just had a thought, sd for a reverse mounted driver may be smaller than for forwards because of suspension and motor assembly. this could have a significant effect on modelling, does anyone know one way or the other?

james.


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 Subiectul mesajului:
MesajScris: Mar Noi 22, 2005 5:11 pm 
james, ind.st scrie:
phil, how much can noise control source the 18 sound 6nd410 for?


We can get `em to you for £54+vat +del. Now if this driver is used in the final specs I`m sure we can sort out a deal on multiples...? I`ll wait and see.

Citat:
using a timber hf horn will drop it a bit.


Are you sure..? getting a tight hf horn outta wood would be a bit tricky and there`s loads of plastic / aluminium horns out there for not a lot?

Citat:
reverse loading the 12s for voice coil cooling is a very good idea
yep! that`s how the the NCA WMD gets away with a very small rear chamber and doesn`t overheat the vc in such a big horn!

Citat:
heat sinking the 6"/8" will be good for mega power handling and ludicrous output plus increased driver longevity, could be worth the (significant) hassle, especially to keep those fancy neo magnets cool!


Funny that! Raey`s working on heat sinks for the 18sound 10`s and 12`s!
In the long run you should have something that`s simple for any cad machine shop to make with the minimum bit change-overs?

Have you seen the heat sink device on the PI2 cab ...look on PSW for the bass shootout thread..lots of arguing between the designer and Tom Danley but the heatsink is a cunning idea ? and his temp reading for a lab12 under high loadings is interesting!

james.[/quote]


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 Subiectul mesajului:
MesajScris: Mar Noi 22, 2005 5:13 pm 
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Guess who didn`t log in! :roll:

.p.


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 Subiectul mesajului:
MesajScris: Mar Noi 22, 2005 5:26 pm 
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using a timber hf horn will drop it a bit.


Ah, but if we make a timber_mg horn instead out of fibreglass we get cheapness, any shape we want, less absorbtion of HF etc etc. Martin has had some good initial results with Oblate Spheroid HF horns. They have very good polars so should be good for arraying. Should be able to make them to any dispersion we want.


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 Subiectul mesajului:
MesajScris: Mar Noi 22, 2005 6:17 pm 
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that's a nice working price phil, cheaper than the b&c and definitely a classy looking cone too.

the heatsink for the pi was indeed my inspiration, the figures he brought back from destructive testing convinced me that it was definitely worth considering, i hadn't really considered the machining of it though.

the reason i was looking into a diy hf waveguide was the dissapointing lack of anything with a narrow enough dispersion for an arrayable box, i am currently envisaging something like a symetrical version of the res 5's square based pyramid for ease of construction and to maintian pattern control of the highest frequencies.

thinking about what graeme was saying led me to consider a similar type of horn for the high mid. the straight sides could help maintain dispersion up to crossover point and the varying expasnsion would be taken care of with the phase plug geometry, in theory...

i haven't been keeping up with martin or martin's oblate spheroids, the main reason i am still thinking wood is a lack of experience with fibreglass or similar and a worry about how repeatable the results will be. this is supposedly an international diy project and should not hinge on one person's set of moulds?

james.


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 Subiectul mesajului:
MesajScris: Sâm Noi 26, 2005 7:24 pm 
If you decide to go with bandpass for the low-mid, you can use the Beyma SM-112N. 5mm xmax, neodimium, and not to pricey(At leat here is like $80dlrs). It's a good reflex unit, dont know If it works ok on band-pass


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 Subiectul mesajului:
MesajScris: Dum Noi 27, 2005 6:28 pm 
Hello,

For the low/mid I would like to see something like a hornload or a bandpasshorn. You really need some moutharea to get the efficiency up to par. It is either that or you need lots of power to keep up with the mid/highs. It depends very much on music style but there can be a serious amount of energy in the 80-300Hz range. To give some idea how load a single X-tro can be in this range, standing in front of it made the bones in my head vibrating. There was a very strong pressute acting on the area just below my ears. This was very uncomfortable. Still the power in this range is no overkill compared to the 8"/1" section. We are talking theoretical 135dB halfspace max from 80-300Hz. The advantage of the short horn and closed back chamber is the very good impulse response. Short strong transients come out of the cabinet the way they were recorded. I have my doubts if a higher order bandpass design will give this sort of sound quality. I would try to keep it forth order, in case of W-bins designs I would not use a vented back chamer.

A big problem when choosing an arrayable cabinet is the trapeziodal cabinet shape which will make the construction very difficult in case of a complex inner layout of the cabinet. In that case double mitres are the order of the day. Only experienced people can build such a cabinet.

Also I would like to point out that a good midhorn with a 6" or 8" driver may not sound as loud as some people would expect. A more agressive sounding hornloaded 10"/2" may have some advantages when it comes to maximum SPL. As a guideline, we tested the X-tro at full power and the maximum SPL between the midbass/mid/high seem to be well mated. They run out of steam at the same time. Talking free air theoretical maximum SPL this means with crossover at 300Hz and 2500Hz the maxi mum SPL from the midbass should be around 3dB more than the midrange and mid should be around 2dB louder than the highs. This is for modern dance and pop music, west Europeen ears. I understood in the USA a slightly agressive sound is more popular. Here in the Netherlands most people prefer the Funktion One type of sound.

Best regards,

Walt


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 Subiectul mesajului:
MesajScris: Dum Noi 27, 2005 9:12 pm 
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this is what I designed so far, I taken into acount only the internal volumes at this stage.
the dimensions of the box are ramdom

take a look at the spl @ 1W imput

http://www.stocare.as.ro/nexus.pdf

the peak around 250Hz is caused by the extreme small encloosure

I prefer a small enclosure with a peak that can be eliminated with the EQ, than a larger one.

Yes I know it's not horn loaded, but it's small 8)

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MesajScris: Dum Noi 27, 2005 9:47 pm 
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Hello,

I noticed the ports of the side chambers are only 1 cm long. I think it will be quite difficult to realise this. There is the danger that the walls of the cabinet will change the tuning of these ports.

Also according to LSP CAD the groupdelay is about 10ms at 80Hz which is a bit much (as a guideline groupdelay < 400/freq)

Best regards,

Walt


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 Subiectul mesajului:
MesajScris: Dum Noi 27, 2005 10:08 pm 
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Yes I've adressed the problem, by using round ports which are deeper for the same tuning frequency.

I want to use this midbass design in my Outline Doppia clone

the only thing I'm worried about is the sound of a bandbass that high in frequency (300Hz)....

I have never used bandpass above 100Hz..... :roll:

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 Subiectul mesajului:
MesajScris: Lun Noi 28, 2005 12:15 am 
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wonderful to see you're in on this too walt, i am excited to see how many experienced and respected designers are joining the group and i feel sure that some really good stuff is going to go off here.

with you all the way on the low mid loading, last night we ran a modified 12" decware wicked one under two martin 215 mk1s, the straight horned martins delivered tremendous kick but didn't quite integrate with the mid top array, the sub was very nice. the wo is a 4th order bp horn hybrid in a very tidy little box. we are jiggling the size to the same footprint as the in-progress mkIII 215s.

looking around, many of the truly awesome bass/kick cabs out there employ some kind of bp horn combination. the hd15 and the wo are really not a million miles appart, even though a glance at the layout of both will confirm the difference in the front chamber and throat size sorts the tuning of the chambers. the horn on the end of that is more in the region of a nicely directional highly efficient port.

looking at the mkII x-tro walt i kind of envisage that to be having a similar kind of principle, there is no doubt in my mind that your low mid section will share the tight and dynamic 'in your face' sound that the other cabs demonstrate. (i could go on about that wo for ages, it really is shaping up to be a very nice one box subwoofer. course we'll have lots...)

i don't think that we are ever going to make a trapezoidal arrayable horn loaded mid top without a large number of double mitres. i am prepared for the worst for this reason. whilst the techniques involved may be quite tricky, we have the capabiliy of producing a wicki thingumy for the construction. again, with as many minds coming at it as possible this could be a wonderful educational resource and give people some really coherent and well documented build pictures and instructions.

finally, i think any trade off in high mid driver size could be offset by a tighter pattern control from the cab, by slightly downsizing the choice of drivers all round but tweaking efficiency right up you might find the same performance balance to cover a narrower segment, which is kind of what i'm interested in. as you'll always be running two a side you can factor in the coupling of the cabs low mid sections.

james.


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MesajScris: Lun Noi 28, 2005 1:08 am 
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Now I see Walt is in on this, I may well hold off building my Xtro's until I see what happens here.

:D


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