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Maybe a smaller cab for 15" driver ?


fleabag
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Rather then get rid of a huge Peavey BVX cab i have with a 15" 600 watt Fane Sovereign LF driver, and the fact that no one wants to buy this,

I figured i may as well keep the driver but stuff it in a more reasonable box.  The current Peavey cab which originally housed a Black Widow, is pretty big

I did some measurments,  turns out to be about 7.22 Cubic feet.  Allowing for the fact that i measured outside edges, perhaps a bit less, say 7.0 cubic feet and this equates to about 198 litres.

Now on the Fane website, they have recommendations for volume , both Cubic ft and Litres.  Even the biggest at  4.41 Cubic ft / 125 litres is way smaller than the Peavey

I'm not sure about their smallest recommendation  of 1.76 cubic ft / 50 litres ???

They also dont mention porting / port sizes.  What minimum size ported cab could i reasonably get away with in size, without killing the bottom end ?

Problem 2 is the fact that i live in a flat, with nowhere to work ( no shed ) and no power tools to speak of.  This means i will have to pay someone to build it

From the FANE site ...

QWIRreq.jpg  YoIxDwg.jpg

 

 

Edited by fleabag
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Cheers for that link - having a read right now

Believe me, someone would have to build it for me for the reasons stated, and yes, coin would have to be exchanged for services rendered

I'm looking at where i can buy Baltic Birch locally at the mo.  Havent founds much round these here parts

Edited by fleabag
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Your builder of choice might offer suggestions as to a modification such as leaving the surplus driver out and recalculating the overall cab volume.  Also, I think you might find more stuff like that if you do a 'net search from time to time.  It's an interesting project.

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Firstly, both the fearful and Simplex designs are optimised for particular speakers, so they will not work as well with your drive units.

Secondly, as you reduce the box size, you tend to get more boom in the sound - the response develops a peak in the 100-200 Hz range. A little of this may be to your advantage, but too much will sound bad.

Given the information on the drive unit that you have from Fane, you could download a copy od 'WinISD', follow the instructions about adding that information, and let it design your own speaker box, while you adjust volume and porting see what effect it would have.

David

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Thanks everyone  - will check Bill's Simplex cabs. Had a Jack 2 x 12 in the past, very nice. I didnt build it though - bought it here on BC

I've tried WinSD in the past, but not being a techie, i got confused over the graph results. When i fitted 4 Beyma SM/110's to my 2 other cabs,  Stevie / Phil etc worked out all the port sizes and i ended up with a very nice pair of 2x10 cabs. I even bought the Beymas on their recommendations

Stevie - those plans are for the Colossus drivers,  which top out at 1.5khz  , so does that mean they're more Sub than my Sovereign, which tops out at 3.5khz ?

125 litres is way better than the Peavey cab,  and this is the biggest volume Fane state ( as you can see in Fanes recommendation )  and i wonder if that's because its a Sovereign, and not a Colossus, which i presume needs more low end, and therefore a bigger design ?  I could be talking rubbish - i wouldnt know :)

 

 

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The size of the cabinet won't make any different to the high frequency response of the speaker. I modelled that 125-litre cabinet for the Sovereign 600 and it works fine. I wouldn't be too keen on 12mm plywood for a cabinet of that size and power. Without a lot of extra bracing, it will probably vibrate too much. You might get away with 15mm.

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Is it possible to place the 4 ports at the rear instead ?    I was just thinking of the height needed to squeeze a 15 and 4  x 100mm ports in the front baffle.

I dabbled with some conversion tables to get roughly 4 cubic feet / 113 ltr and approx, it came out as 27"  tall,   17" wide , 15"  deep  ( 3.98 c/ft )

I may need to increase that as you recommended 125 litres is better. ( 4.41 C/ft )

 

Re calc :  27" h x 17" w  x  17" d  =  4.51 c/ft

http://www.thecalculatorsite.com/misc/cubic-feet-calculator.php

Edited by fleabag
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I'm not a fan of rear porting for bass guitar cabs. If you'd like to use a cab of those dimensions, you could use two 5" or 6" ports, which will fit comfortably on a 27 x 17" baffle. There is also the option of a shelf port, but that's not as easy to calculate reliably using modelling software.

Edited by stevie
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I'm happy enough to use front ports Stevie - was just curious.  I'd prefer to use 4 ports though , as in the plan, so what size area of front would i need

to fit 4 ports ?  I can adjust the sizes around to still keep the volume at  4.51 cu/ft

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On ‎19‎/‎01‎/‎2018 at 12:56, SpondonBassed said:

For the cab experts; When a cab is tuned to a frequency, 50Hz in this instance, is the effect to accentuate or attenuate the sound for that frequency please?

Tuning the cab to that frequency means the cabinet starts to resonate and produce air movement (sound) through the port. This creates pressure on the back of the cone and damps down it's movement so effectively the port takes over making the sound from the speaker. How the cone moves is controlled by the design of the speaker, the volume of the cab and the tuning. The trick is to balance up the speaker, cab size and tuning so the sound stays the same all the way down and all WinISD and the other programs do is to do the balancing act calculations for you.

So, as the speaker starts to lose output the port takes over and adds in a bit more sound, ideally just enough to keep the sound level the same but lets you go deeper.

  • Thanks 1
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14 minutes ago, Phil Starr said:

Tuning the cab to that frequency means the cabinet starts to resonate and produce air movement (sound) through the port. This creates pressure on the back of the cone and damps down it's movement so effectively the port takes over making the sound from the speaker. How the cone moves is controlled by the design of the speaker, the volume of the cab and the tuning. The trick is to balance up the speaker, cab size and tuning so the sound stays the same all the way down and all WinISD and the other programs do is to do the balancing act calculations for you.

So, as the speaker starts to lose output the port takes over and adds in a bit more sound, ideally just enough to keep the sound level the same but lets you go deeper.

Thanks Phil.

I was curious because of the dreaded 50Hz mains hum that sometimes gets past all of the screening and countermeasures.  For a moment I thought that might have been a design consideration when 50Hz was stated to be a good frequency for reflex bass cabs to be tuned to.

I'm really only scratching the surface in this subject although as a young man, lots of folk had speaker cabinets off me.  I'd buy the drivers and crossovers at Oxford Street on my frequent trips from Dublin to London and put them in cabinets that I'd make to order.  I'd do two and three-way speaker pairs.  The Punt/Sterling (pre-Euro) exchange rate and price differences between the two countries meant I could do this with no expense to myself and at the same time I got to play with basic speaker enclosure projects.

If I was right in the head I could have made good money from my hobby.  It wouldn't have been so much fun however.

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1 hour ago, SpondonBassed said:

I think that's fairly easy to deal with.  The specified port area should be a constant whether it is one port or many, circular or otherwise, no?

Yeah no probs. Just amazed that there's 4 in one cab

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