Hello audio peoples,
I am fairly new to the speaker building community, having built three sets of speakers to date which I'm fairly happy with. However, I'm still overwhelmed by the sheer number of factors and nuances that are involved in this wonderful hobby, but I'm trying to get better with each project. Anyway, to the point at hand...
I bought a pair of the MA Pluvia 7s and am thinking of using them in my mid-sized living room. The enclosures I'm thinking of using (just under 3 liters in volume) would sit on bookshelves mounted to the wall, and they would be supported by a separate subwoofer hidden behind the sofa, so they don't have to do much low bass production. I was thinking about putting a high pass filter on the driver with a value somewhere between 100 and 200Hz, so the Pluvias would only have to handle freqs above that. I've tried modeling this in BassBox 6 Pro but the graphs all look like a mountain, with a peak at about 130Hz and a steep drop off on both sides, which seems impossible. This is for a closed box enclosure. I've also tried this with a vented box and its not much different. So either I'm doing something wrong (I've checked all my S/T parameters that I've entered in Bassbox) or this driver cannot be used like that. Anyone have any ideas on whether my plan will work or not or is this just a dumb application of these drivers? Any help from you guys would really be appreciated! Thanks!
I am fairly new to the speaker building community, having built three sets of speakers to date which I'm fairly happy with. However, I'm still overwhelmed by the sheer number of factors and nuances that are involved in this wonderful hobby, but I'm trying to get better with each project. Anyway, to the point at hand...
I bought a pair of the MA Pluvia 7s and am thinking of using them in my mid-sized living room. The enclosures I'm thinking of using (just under 3 liters in volume) would sit on bookshelves mounted to the wall, and they would be supported by a separate subwoofer hidden behind the sofa, so they don't have to do much low bass production. I was thinking about putting a high pass filter on the driver with a value somewhere between 100 and 200Hz, so the Pluvias would only have to handle freqs above that. I've tried modeling this in BassBox 6 Pro but the graphs all look like a mountain, with a peak at about 130Hz and a steep drop off on both sides, which seems impossible. This is for a closed box enclosure. I've also tried this with a vented box and its not much different. So either I'm doing something wrong (I've checked all my S/T parameters that I've entered in Bassbox) or this driver cannot be used like that. Anyone have any ideas on whether my plan will work or not or is this just a dumb application of these drivers? Any help from you guys would really be appreciated! Thanks!
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It is impossible, that's the downside to purely mathematic based calculations (not that BBpro is a bad box designer for simple enclosures -it's quite good).
Depends what you are referring to by a high pass; 130Hz is a bit on the low side to avoid excessive changes due to the rising impedance around tuning / resonance, especially if low order. This is a fairly common issue with very low XO frequencies, reduced somewhat with it raised a bit. Always a tradeoff.
Depends what you are referring to by a high pass; 130Hz is a bit on the low side to avoid excessive changes due to the rising impedance around tuning / resonance, especially if low order. This is a fairly common issue with very low XO frequencies, reduced somewhat with it raised a bit. Always a tradeoff.
atreynolds,
If BassBox 6 have feature to export response and impedance as frd and zma files, you could try out free XSim and see if over there in XSim by linearize impedance somewhere can get your desired response, here is link to XSim http://www.diyaudio.com/forums/software-tools/259865-xsim-free-crossover-designer.html.
Other possibility is if your Pluvia 7s have dedicated power amp not shared with subwoofer then you could do the passive XO at input of power amp where impedance is nice flat instead of the normal at output, math for PLLXO (Passive Line-Level Crossover) is to find at this link and notice at top there is a nice helping spreadsheet for calculating values shared for download TLS.org | Passive Line-Level Crossover.
If BassBox 6 have feature to export response and impedance as frd and zma files, you could try out free XSim and see if over there in XSim by linearize impedance somewhere can get your desired response, here is link to XSim http://www.diyaudio.com/forums/software-tools/259865-xsim-free-crossover-designer.html.
Other possibility is if your Pluvia 7s have dedicated power amp not shared with subwoofer then you could do the passive XO at input of power amp where impedance is nice flat instead of the normal at output, math for PLLXO (Passive Line-Level Crossover) is to find at this link and notice at top there is a nice helping spreadsheet for calculating values shared for download TLS.org | Passive Line-Level Crossover.
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That is a big help!
I'm looking at switching from a .3cuft (8.5liter) vented to a .15cuft sealed in my Pluvia 7 line array project. This gives me hope at actively passing them (subs & P7's) @ ~150Hz. The subs will be located right there under the P7 arrays.
EDIT: The one thing that's probably not realized by most people is that these P7's have excellent high frequency off-axis response. Who knows why MA chose not to have them plotted?
I'm looking at switching from a .3cuft (8.5liter) vented to a .15cuft sealed in my Pluvia 7 line array project. This gives me hope at actively passing them (subs & P7's) @ ~150Hz. The subs will be located right there under the P7 arrays.
EDIT: The one thing that's probably not realized by most people is that these P7's have excellent high frequency off-axis response. Who knows why MA chose not to have them plotted?
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I'm very tempted to build a pair of small bookshelf speakers with these. I want to compare them to my CSS EL70eN and I sort of need a pair of speakers for my kitchen so I don't have to play on my living room stereo and annoy all the neighbours when I'm cooking food. I can get a pair from KJFaudio in the UK for £108 which is a fair price for a pair of kitchen speakers. However not sure how I would go about building the cabinets without proper tools and a place to build them. One option would be using ready-cut boards of ash, pine, spruce, beech, or oak in 200 or 250mm width. Maybe 250mm on the sides for a 250mm depth and then 200mm for the rest for a width of 200+material thickness.
Would it be a bad idea to build a speaker from this kind of board material?
Would it be a bad idea to build a speaker from this kind of board material?
that sort of material is generally OK as the staves are glued in such a way as to be stable. I supply my kits in birch ply usually. The Pluvia is a great starter driver for DIY when you haven't got all the kit like routers as you don't really need to rebate it. Just a hole cutter will do you. I could of course price you an easy to build kit.
Thank you very much for your reply. I have previously built two speakers with birch ply but the panels were all CNC-cut and fit perfectly. Now I don't have access to CNC anymore.
Could you send me a private message for an easy build kit, including shipping to Sweden? I did some calculations and I can build a pair of cabinets in beech for ~£34 or ash for ~£47 with only easy cuts.
Apparently the driver cutout for the Pluvia 7 is a convenient 100mm. I know my dad has a hole cutter kit but I don't know if it has one that big. Otherwise I can get a new 100 or 102mm one for ~£10-15.
I calculated the total cost for a pair to be ~£165-£180 depending on if I choose beech or ash.
I certainly have thot about it… and th esolid materials Bernie & Scott use for their solid builds is essentially a home made version of this.
For P7 you want volume between 5-13 litres.
dave
Alright, but how do I go about calculating port size? On page 3 of this thread you posted a 7.5L vented cabinet with a slot port. However, the port width there is 140mm and I will have 200mm. Should I use the total "volume" of the port which gives me a port length of 103mm compared to your 147mm?
Easiest would be to retain the vent length and change the vent height so that it is the same area. Alternatively you could add a 60mm wide vent spacer to the 12mm high vent.
Leave at least 20mm between the end of the vent shelf and the inside back of the box when you juggle the box dimensions. Adjust the vent shelf length to accomodate the different material thickness (ie keep vent length to 147mm)
dave
Leave at least 20mm between the end of the vent shelf and the inside back of the box when you juggle the box dimensions. Adjust the vent shelf length to accomodate the different material thickness (ie keep vent length to 147mm)
dave
Changing the height would probably be the easiest. It would give me ~8.5mm height. Is that fine or is it too narrow?
I could quote you no problem for a simple design with a slot port like Dave posted above, it would be more expensive than the amounts you are taking about above though.
If you do buy that board just check the growth ring direction by looking at the ends. To stop it warping the should swap direction alternatively.
Even better would be to find a board that thr growth rings run face to face or diagnal (quarter sawen or rift sawen) alternating directions of flat sawen or curved growth rings is a good idea but one flat sawen board in the middle could cup the whole panel. Most of the time wood will want to cup in the opposite direction of the curve of the rings.
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