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Darkstar View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Darkstar Quote  Post ReplyReply Direct Link To This Post Posted: 22 October 2014 at 2:20am
This is the link to the RCF 4pro 6001 plans with all the fancy stuff.
I must say it's pretty detailed, it misses the angles tho.

http://hornplans.free.fr/4pro. - http://hornplans.free.fr/4pro.html

Edited by Darkstar - 22 October 2014 at 2:21am
Bass =/= Enough
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MattStolton Quote  Post ReplyReply Direct Link To This Post Posted: 22 October 2014 at 11:24am
Whilst I  understand your constraints on size, i.e. van pack, it is my interpretation of diapolito type arrangements, that in the layout you have, you will get narrow horizontal dispersion,and wide vertical.

The RCF layout of the 2x12" gives wide horizontal and narrow in the vertical, which would be my preference.

Whether "V" baffle actually does much, or even does anything in the pass band of your 2x12", may make all of that moot any way.

I do remember a project the late windmill tilter did, which was 8x8", 2x 4 drivers high, on a horizontal v folded baffle. He reported a notch at about 800hz IIRC, which he attributed to a dimension causing an interference. If you are crossing at 400hz, I doubt you will get any issue, but worth noting if you get some anomaly.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ceharden Quote  Post ReplyReply Direct Link To This Post Posted: 22 October 2014 at 6:39pm
The point about the driver arrangement and dispersion is quite valid at higher frequencies, however I would be very surprised if my low-mid section exhibited any noticeable directivity in the range up to 400Hz.  The acoustic centres are only about 200mm apart which is less than a quarter wave at the crossover point.

If you look at cabs such as the D&B Q Series, they manage to get up to a crossover point of 1.3kHz with the drivers at each end of the cab (acoustic centres must be about 400mm apart).

I believe the deep V-baffle gives quite significant gain in my case.  Probably a lot less for the RCF cab.  It's not all good because it does also reduce the usable frequency range and you can easily end up with some large peaks, I've had to take out about 6dB at 200Hz to flatten the response.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote MattStolton Quote  Post ReplyReply Direct Link To This Post Posted: 23 October 2014 at 11:37pm
If your looking for a compact cab, why not put each 12" above/below the 8" horn, with the HF in the Mid horn mouth? Proper point source, with a little DSP adjustment for phase/alignment. Feck, go some weird band pass design for the 2x12", deliberately peaky 120-400 Hz?

Given how low you are crossing to the 8", and your reference to the D&B Q series, some merit in building the top and bottom sides of the 8" horn up to bounce the 12"'s waves? 400Hz is about 0.8m wavelength, so you can be quite some space apart before weird shizzle kicks in?

TBH, pissed up musings, from a lazy keyboard jock, after a 1.6Kg T Bone steak and a bottle of Barollo. Must send the wife off with the kids more often.....
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ceharden Quote  Post ReplyReply Direct Link To This Post Posted: 24 October 2014 at 12:06am
All good ideas and I've considered a few of them over the years.  If I didn't care about making my life easy and avoiding compound mitres etc, there are some much more clever things I could do.

What would be really nice is to have the HF compression driver and horn form part of the phase plug for the 8", however that would require using a much smaller 1" horn flare and I quite like the 18Sound one I've got.  The baby Faital Pro horn would probably be a good option if I wanted to go down that route.

Regarding wierd bandpass designs, that's essentially what I've got, it's pretty peaky in that range already.  The version I'm planning to try next will probably be even more so.  I was tempted just to do a PPSL (Push-pull slot loaded) but I like the extra radiating area you get from more of a V-shape.

I might end up needing to push the crossover to the 8" a bit higher just for power handling.  The 8" is definitely going to be the section that's doing the most work.  I'm actually eyeing up some alternative drivers with slightly large voice coils.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Thomas Hosker Quote  Post ReplyReply Direct Link To This Post Posted: 09 November 2014 at 9:43pm
Any progress Chris?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ceharden Quote  Post ReplyReply Direct Link To This Post Posted: 09 November 2014 at 10:58pm
Unfortunately not.  I've had a run of weekend where I've either been away or just generally unable to make it to the workshop.  Unfortunately I'm also affected by Saints (Southampton FC) home games as the warehouse carpark is used for match parking and it's just too much of a ball-ache to work down there on those days.

I have been looking at some alternative 8" drivers which look interesting  but I'm waiting for Bluearan to place their next order with the manufacturer.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Thomas Hosker Quote  Post ReplyReply Direct Link To This Post Posted: 10 November 2014 at 5:32pm
Good luck with that! Youll be waiting a while :/

Are you sticking with your original plan then or has it evolved?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote ceharden Quote  Post ReplyReply Direct Link To This Post Posted: 10 November 2014 at 8:34pm
At the moment still sticking with the same sort of idea.  I need to prototype the revised low mid section in a trap cabinet.
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