PD drivers are assembled in the UK from parts made around the world including China; they have not been fully 'British' speakers for some time.
RCF 21" Bought on price!
In my experience it is extremely difficult to build a bad sealed enclosure even within fairly wide limits.
Take a look at the other 21" drivers sold by Blue Arran.
Ply is slightly lighter than MDF, tougher, and more suited to life on the road! For home use, whatever sinks your boat!
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Yeah its better to try than worry beforehand. DSP relieves so much design options for loudspeaker systems so avoiding it just because seems silly. There are worse and better DSP implementations, use a good one. Although, when it's not necessary to use one then don't.
Well, you must evaluate that yourself. I used chinese adau1701 board with chinese amps at first, liked the DSP except the whole system was noisy. Now I'm using quite cheap t.racks DSP408 with icepower amps, dead silent system so as good as I can hope for now.
As disclaimer, I do not have passive speaker to compare with. I'm quite sure DSP enables my system sound better, not worse. I guess, at some situation, with some loudspeaker in some room with some expectations DSP could make sound worse. If you notice sound got worse and nothing helps, then get rid of it and replace with active or passive analog solution, or change the system to something else if it doesn't work without. Sometimes people have fully analog chain and want to avoid AD/DA conversion, and that's fine, important thing for them. I'm looking for very good sound and currently exploring with DSP, perhaps after ten yeas I've switched to analog, but I do not know before enough experience, keep open mind.
As disclaimer, I do not have passive speaker to compare with. I'm quite sure DSP enables my system sound better, not worse. I guess, at some situation, with some loudspeaker in some room with some expectations DSP could make sound worse. If you notice sound got worse and nothing helps, then get rid of it and replace with active or passive analog solution, or change the system to something else if it doesn't work without. Sometimes people have fully analog chain and want to avoid AD/DA conversion, and that's fine, important thing for them. I'm looking for very good sound and currently exploring with DSP, perhaps after ten yeas I've switched to analog, but I do not know before enough experience, keep open mind.
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In at least some locales, musical venues they're legendary bass/mid horn drivers, so lucky you being so close if can get better prices! 👍 😎
I just built a dual 21" sealed sub with the SB Audience NERO21SW1100D. It's heavily braced with a 18mm plywood internal construction and a 12mm black MDF finish glued on making it 30mm in total. At the moment the amplification is done with one Crown XLS1002 in bridge mode. Needless to say I'm very happy with it. The only thing that I'd change (and if I had the room for it) is making it a dual opposed construction.
@Frank207be is yours a cuboid?
My intention right now is to build two of these sealed subs so I can park one next to each of my main speakers.
I was probably going to use something like a crown or a matrix amp at least until I can find something classier for a reasonable price.
My intention right now is to build two of these sealed subs so I can park one next to each of my main speakers.
I was probably going to use something like a crown or a matrix amp at least until I can find something classier for a reasonable price.
Running also mains thru DSP-xo gives many advantages
- total control of both LP and HP acoustic response and xo freq. I prefer LR2, which is practically impossible to achieve passively (you need big and capable mains and expensive components for the xo)
- total control of sub/main timing (delay for mains)
- best control of room response as high as one wants (in main speaker territory too)
My choice is Minidsp 2x4HD. It has only two input channels, which means that with multichannel source one should use second unit for .1 (LFE) or disable LFE. Sound quality is just fine, no audible noise etc. problems. Flex and SHD models have better DAC performance but different functionality, I haven't used them.
https://www.audiosciencereview.com/...urements-and-minidsp-2x4-hd-dsp-and-dac.2674/
@Juhazi that's great to know. Yeah I have nothing against DSP for the mains other than perhaps a bit of mental anguish that my otherwise entirely analogue chain of mostly restored 70s and 80s gear is getting ADC and DACed.
But I'll let my ears do the deciding, this all seems like a long way off for now though.
But I'll let my ears do the deciding, this all seems like a long way off for now though.
Mine are 120cm x 79cm x 67cm
Here a "family" photo of the new sub and the older converted ones in white enclosures with B&C 21SW152/8
Bracing:
Buy the Crown XLS2502PA and you'll never need anything classier. I have 2 of these and they sound great and are near silent.
Wow, that's quite something! Thanks for sharing those pictures.
Out of interest, when doing a Volume & Qtc calculation, do you take into consideration the volume of air the bracing displaces? Ie more bracing equals a small volume for the same size cabinet dimensions... or is that unnecessarily fussy.
Out of interest, when doing a Volume & Qtc calculation, do you take into consideration the volume of air the bracing displaces? Ie more bracing equals a small volume for the same size cabinet dimensions... or is that unnecessarily fussy.
Yes I´ve calculated the volume bracing included but indeed it doesn´t matter as much as with ported enclosures or other more advanced speaker designs. I wanted to get as close as possible to a QTC of 0.5 but I settled with 0.56 as the enclosure would become too large.
Cool. If I understand the original design doc I linked originally, the guy went for a 0.5Qtc but then has massively overspeced the size of the driver and power available so that the cab could produce SPLs he'll never need - allowing him to just EQ those lower frequency back up - an idea I quite like.
So I am aiming for 0.5 - but probably not lower. I'll try and reverse calculate whether those original plans I linked took the bracing into consideration.
So I am aiming for 0.5 - but probably not lower. I'll try and reverse calculate whether those original plans I linked took the bracing into consideration.
Hi, nice 😀Mine are 120cm x 79cm x 67cm
Here a "family" photo of the new sub and the older converted ones in white enclosures with B&C 21SW152/8
Bracing:
Buy the Crown XLS2502PA and you'll never need anything classier. I have 2 of these and they sound great and are near silent.
120cm dimension, woofer at one end, makes maximally excited 145Hz resonance inside the box. Do you have blip on impedance plot? 🙂 What low pass you use, do you need to dip the resonance with EQ?
You could halve the longest dimension and adjust system Q to 0.5 with EQ, for almost any sensible Fs. This would rob from max SPL capacity, but for home use such big cones and powerful amplifier ought to have plenty oomph available.
Well, it's just something one can do, reduce size sacrificing some SPL capability, size reduction reduces panel area and pushes internal modes higher up, both should clean up sound of such box, if it was an issue in the first place.
It all starts with driver choice. The lowest Qts 21" woofers are between 0.2 and 0.3 while other already have values over 0.5. I'd also look at x-max for such a design. My SB Audience NERO 21SW1100D have 12mm and the B1C 21SW152 have 15mm
@tmuikku:
Both drivers are internally separated by a sealed panel (invisible in the bracing photo) so the longest internal distance is 71cm top to bottom 😉
I only performed listening tests and didn't do any measurements. These 4x 21" woofers together with the 4x 15" woofers in front of the room do 17Hz without boost so I'm quite happy. The crossovers from the Crown amps are all disabled and the only one in use is the 24dB/oct LR @100Hz from the AVR. I've calibrated my room with Audyssey MultEQ-X without any boost. I've only dialed up the gain about 7dB on the Crowns after calibration and the system sounds tight, deep, limitless and above all very natural both in stereo and surround.
Both drivers are internally separated by a sealed panel (invisible in the bracing photo) so the longest internal distance is 71cm top to bottom 😉
I only performed listening tests and didn't do any measurements. These 4x 21" woofers together with the 4x 15" woofers in front of the room do 17Hz without boost so I'm quite happy. The crossovers from the Crown amps are all disabled and the only one in use is the 24dB/oct LR @100Hz from the AVR. I've calibrated my room with Audyssey MultEQ-X without any boost. I've only dialed up the gain about 7dB on the Crowns after calibration and the system sounds tight, deep, limitless and above all very natural both in stereo and surround.
I would not use a simple MiniDSP 2x4 for your KEFs/Main Speakers. These small and cheap units are nice to do some tests but specs and sound is far from what would fit a system like yours. Don't buy the cheapest DSP available and then say "DSP is not sounding good" ;-)
Adding DSP to a system normally IMPROVES the sound cause you can fit speakers and room. But you need to know about acoustic measurements and take your time.
Woofer construction - this cube is totally fine, don't worry. Braced that much panel resonances are no problem. When you build braces like that you actually don't need to make all of these holes in the braces! It takes more volume but is WAY faster to build and divides your volume in smaller ones -> less resonances. Just have enough room behind your driver so there is no restriction of "airflow" (pressure propagation is a better wording? There is no air "flowing" here).
I fill these volumes with sheep wool (not to dense) and never have any problems with resonances again.
Q of 0,5 is less critical as it seems on paper. As long as the volume is closed ... 🤓 even a Q of >0,7 sounds way better and is more stable with voice coil temperature and coil movement as any reflex construction.