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Dual 15" subwoofer, rcf design?
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Tonskulus View Drop Down
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    Posted: 31 October 2017 at 6:11pm
I just got two subwoofers for quite low price. Seller told me that these are made by RCF but is that so?  Someone seen these before ?

Drivers are RCF L15P540, two drivers / unit facing each other.  Tuning frequency is around 50Hz.  How about the sound? Well, nothing special..pretty tight. But single hog scoop is much louder I can tell you. 
I think LF15G401 would be better driver option.. 






Edited by Tonskulus - 31 October 2017 at 7:47pm
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Doesn't look like any RCF box I know. Look for some sort of markings or at least a sign of proprietary components. RCF boxes - even old ones - usually have custom handles etc.
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Couldn't find anything.. backplate has been changed to speakons (originally equipped with 6.5mm / xlr?).

hmm, somekind of bandpass/manifold it is. Front chamber having quite high tuning frequency of >130Hz I think.

Any known advantages compared to standard 2x15 BR?  Except smaller size..



Edited by Tonskulus - 01 November 2017 at 8:50am
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manifold mounting gives 3dB bass boost compared to bass reflex.
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Do you have some more pictures?
Based on the current picture only, I doubt this is a genuine/original RCF speaker.

First of all, the L15P540 is not that old, which would suggest the cabinet is not that old either. And thus the cabinet (model) would be more well-known also.

Second, that grill looks very DIY to me. For example because the mesh isn't closed around the edges, so it is just cut from a large piece of metal sheet.

Last, I do not think RCF would leave a part of the cabinet unpainted when it is exposed like this (even with grill attached).
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Originally posted by 4AC 4AC wrote:

Do you have some more pictures?
Based on the current picture only, I doubt this is a genuine/original RCF speaker.

First of all, the L15P540 is not that old, which would suggest the cabinet is not that old either. And thus the cabinet (model) would be more well-known also.

Second, that grill looks very DIY to me. For example because the mesh isn't closed around the edges, so it is just cut from a large piece of metal sheet.

Last, I do not think RCF would leave a part of the cabinet unpainted when it is exposed like this (even with grill attached).

Yes, I think it's diy too.. just wondering that design and those drivers.

btw, drivers are NOT original, but previous owner told me that original drivers were RCF too. Just not sure if they were same type or not.. propably not because if I had made that designg, I would use different drivers anyway :)

Rear chamber is 180-190 litres, tuned to 50Hz. 






Edited by Tonskulus - 01 November 2017 at 11:36am
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"manifold mounting gives 3dB bass boost compared to bass reflex."

Only over a narrow range, and only if you have the correct drivers.

"drivers are NOT original,"
djk
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Originally posted by _djk_ _djk_ wrote:

"manifold mounting gives 3dB bass boost compared to bass reflex."

Only over a narrow range, and only if you have the correct drivers.

"drivers are NOT original,"

Seller told me that original RCF drivers (3 out of 4?) has been broken and new RCF drivers were installed.  I didn't ask more about them, just gave him my money and took off :D 

So not original but possibly same type anyway.. who knows.
Enclosures are really well made, lots of bracing and precisely cutted parts.  But yes, indeed looks like these are somekind of DIY.  Just cannot find any similar/identical desingns, so dunno if it has been well known design in the past or did someone made his own..

How about sim, should I use 6th bandpass or reflex simulation?  As being manifold design, well.. it is a kind of 6th order bandpass?




Edited by Tonskulus - 02 November 2017 at 6:10am
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Something weird there is, I played these subs a bit "harder", psy trance music having tight bass mostly 40...60Hz. 
Drivers start "flapping" at 500Watts (300W / driver) input. At 300W its clean BOOM BOOM, but 600W makes it sound more like BFLOP BFLOP and sounds like over excursion. Looking at drivers, cones are moving around 10mm.  My 18" RCF subs can take cone movement of >20mm and no flapping problems!

Amplifier is not clipping.. not even close when this happens as there is still some room to increase volume before clipping occurs. Amplifier is Tamp TA1400, 4ohm load / channel. 
Is it possible that L15P540 is not good for this kind of enclosure and goes out of control or what..?  These drivers should take 1kW each according to specs.. 







Edited by Tonskulus - 02 November 2017 at 6:08pm
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If the cones don't seem to be moving far and they're exceeding xmax, you may have gotten some rcf knock-offs in there. Lots of them about lately and if the previous owner tried to repair on the cheap he may have used them. They can sound okay but low xmax and power handling is typical.
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Tonskulus View Drop Down
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Originally posted by Hemisphere Hemisphere wrote:

If the cones don't seem to be moving far and they're exceeding xmax, you may have gotten some rcf knock-offs in there. Lots of them about lately and if the previous owner tried to repair on the cheap he may have used them. They can sound okay but low xmax and power handling is typical.

Yes, well.. I have to check out some other (better) driver options for these.  Fane colossus prime 15xb looks quite good for a price, as example. 



Edited by Tonskulus - 02 November 2017 at 7:17pm
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If only 3 of 4 were replaced maybe test to see how the original driver behaves run on it's own.
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