I'm planning to build a variation of Timn8ter's Aura PC Speakers. I've just received a pair of 3" PE drivers that look like black-coned versions of the Aura NS3-193-8A drivers, but noticed that the T/S parameters differ from the Aura specs. Fs is 100hz vs Aura spec'd 80hz and Vas is 0.03 cubic feet (0.85l) compared to Aura spec'd 1.25l.
Assuming the PE T/S parameters are generally accurate, will these drivers work reasonably well in Timn8ter's enclosure? I plan on using these for PC speakers in my office. They will be driven by a Sonic T-amp and will not be pushed very hard.
I'm attaching a couple of drawings of the enclosure I am planning on building. I've re-dimensioned Timn8ter's tall box to something a little shorter and deeper to better fit my desktop, but the gross volume is close (261 vs 264 cubic inches). They will by fashioned from 3/4" ply. Thanks for any help!
Squib
Assuming the PE T/S parameters are generally accurate, will these drivers work reasonably well in Timn8ter's enclosure? I plan on using these for PC speakers in my office. They will be driven by a Sonic T-amp and will not be pushed very hard.
I'm attaching a couple of drawings of the enclosure I am planning on building. I've re-dimensioned Timn8ter's tall box to something a little shorter and deeper to better fit my desktop, but the gross volume is close (261 vs 264 cubic inches). They will by fashioned from 3/4" ply. Thanks for any help!
Squib
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more info
I should have clarified...Timn8er's original design was a BR enclosure measuring 12 (H) by 4(W) by 5.5(D) inches internally with a 1-inch diameter port of 3-inches in length. Here's a link - http://www.timn8er.com/Aurasound NS3.htm.
I should have clarified...Timn8er's original design was a BR enclosure measuring 12 (H) by 4(W) by 5.5(D) inches internally with a 1-inch diameter port of 3-inches in length. Here's a link - http://www.timn8er.com/Aurasound NS3.htm.
more drawings of my version
Here's another view of my attempted variation on the Timn8er design. My initial attempt to model my shorter and deeper variant in WINSID Pro shows a dip in output between 75 and 65 hz followed by a peak at Fb (60hz). I apologize if I rushed to post basic questions that I could answer myself. I'm struggling to contain my enthusiasm for my 1st build . I'll post a few more drawings for anyone interested in observing another newbie trying to find his sea legs...
Here's another view of my attempted variation on the Timn8er design. My initial attempt to model my shorter and deeper variant in WINSID Pro shows a dip in output between 75 and 65 hz followed by a peak at Fb (60hz). I apologize if I rushed to post basic questions that I could answer myself. I'm struggling to contain my enthusiasm for my 1st build . I'll post a few more drawings for anyone interested in observing another newbie trying to find his sea legs...
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office where the speakers will be used...
Sketchup is pretty addictive! This is a rough rendering of my office. I've posted it because of the cave-like ceiling and wall configuration that I assume will influence the low frequency output. There's just 2.5 inches of clearance between the top of my monitors and the ceiling. I'm on the third floor and the 1:1 roof pitch and low knee walls presented a lot of challenges in organizing the space. The ceiling has already been patched several times (from my taller colleagues standing up too quickly when sitting at my chair). There are some advantages to short stature.
Sketchup is pretty addictive! This is a rough rendering of my office. I've posted it because of the cave-like ceiling and wall configuration that I assume will influence the low frequency output. There's just 2.5 inches of clearance between the top of my monitors and the ceiling. I'm on the third floor and the 1:1 roof pitch and low knee walls presented a lot of challenges in organizing the space. The ceiling has already been patched several times (from my taller colleagues standing up too quickly when sitting at my chair). There are some advantages to short stature.
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Thanks, sreten
Thanks for the comment. Perhaps I should consider ordering another pair of drivers and turn these into bipoles. I'm a little uncertain about the sound field from a rear facing driver, as it will be radiating directly at the 45-degree sloped ceiling rather than a vertical wall. Would placing both drivers on the front baffle be advisable? I assume that it would be preferable to roll the lower NS3 off so that only one radiator is reproducing the upper mid-range and treble...is this correct?
Squib
Thanks for the comment. Perhaps I should consider ordering another pair of drivers and turn these into bipoles. I'm a little uncertain about the sound field from a rear facing driver, as it will be radiating directly at the 45-degree sloped ceiling rather than a vertical wall. Would placing both drivers on the front baffle be advisable? I assume that it would be preferable to roll the lower NS3 off so that only one radiator is reproducing the upper mid-range and treble...is this correct?
Squib
Ahh,
"...the lower driver would have an inductor only filter. "
That's a filter I think I might be able to manage. Looks like another PE order is in my future. Too bad I didn't post these questions before placing my initial order, but I forgot to include binding posts anyways (I just noticed I forgot the binding posts on my sketchup model as well).
Thanks for the help,
Squib
"...the lower driver would have an inductor only filter. "
That's a filter I think I might be able to manage. Looks like another PE order is in my future. Too bad I didn't post these questions before placing my initial order, but I forgot to include binding posts anyways (I just noticed I forgot the binding posts on my sketchup model as well).
Thanks for the help,
Squib
I appreciate the suggestions and information, particularly the suggested 2500hz target for BSC. I'm just trying to determine if the inductor will see 4- or 8-ohms. If its four, I'll try 0.25 to 0.3 mH inductors along with 0.5 mH. If its eight ohms, I'll try 0.5 to 0.8 mH. 
Each driver has a nominal impedance of 8-ohms and will be wired thusly:
Each driver has a nominal impedance of 8-ohms and will be wired thusly:Attachments
Landroval,
Thanks for checking the inductor values. Your results suggest higher values than I had assumed. I'll see about purchasing a wider range of inductors to experiment. I suppose having the extra components around may just provide an excuse for the next project. For those of you in the US, is PE a decent source for inductors, or should I look elsewhere? Also, there seems to be quite a range in cost for air core inductors of comparable mH values. Is there a significant downside to going with a "low end" 20-gauge version (http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=255-048&DID=7)?
These will be PC speakers, and I'm trying to keep the costs down.
Squib
Thanks for checking the inductor values. Your results suggest higher values than I had assumed. I'll see about purchasing a wider range of inductors to experiment. I suppose having the extra components around may just provide an excuse for the next project. For those of you in the US, is PE a decent source for inductors, or should I look elsewhere? Also, there seems to be quite a range in cost for air core inductors of comparable mH values. Is there a significant downside to going with a "low end" 20-gauge version (http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=255-048&DID=7)?
These will be PC speakers, and I'm trying to keep the costs down.
Squib
Basically the only really important downside of coils made of thin wire is their high DC resistance (and power handling, but not in this case). This will directly attenuate your 0.5-driver also below the wanted BSC. However as we talk about DCR's between 0.1 and 1.0 Ohm, it doesn't really make a huge difference, especially in a nearfield pc-speaker. If you want to the maximum performance you should have DCR in the 0.1-0.3 range, but if it's higher it won't hurt very much.
And just to point out my sims were made with the 9x5,5 baffle. If you add an other driver you'll need around 6-8 liters of cabinet volume so it might be practical to increase the size of the box and baffle to all directions. This would mean the BSC coils should be of slightly higher value than what I suggested.
And just to point out my sims were made with the 9x5,5 baffle. If you add an other driver you'll need around 6-8 liters of cabinet volume so it might be practical to increase the size of the box and baffle to all directions. This would mean the BSC coils should be of slightly higher value than what I suggested.
Thanks again Landroval!
Unfortunately, I'm now quite confused. Let me just back-track for a moment, and please keep in mind that all of this is quite new to me. I have been toying with the idea of a fullrange PC speaker for some time and had originally planned on using zilla's small sealed HiVi B3S design - primarily because of the relative simplicity and low cost. I've been curious as to how good these inexpensive drivers could sound. I subsequently read Zilla's small driver comparison and started to explore the Aura NS3 as another possibility. Timn8er's Aura PC Speaker seemed perfect and something I thought I could manage. However, the Aura's always seem to hover around twice the cost of the HiVi's. There both cheap in the grand scheme of things, but as these speakers will be for my office, and I have a 2nd child on the way, I was still leaning towards the HiVi.
Move forward a couple of weeks...
As I compulsively cruised the PE extended range driver listings I saw an un-named driver that looked like a black-coned NS3 for less than $9. The reviews on the PE site suggested it was in-fact the Aura NS3-193-8a, so I jumped. It was only after I ordered the drivers that I noticed the T/S discrepancies between the PE drivers and the official Aura specs. As Timn8er chose his design so that BSC was not necessary (http://www.diyaudio.com/forums/showthread.php?threadid=51033), I assumed I might just re-dimension his enclosure, keeping the gross volume the same and be safe.
I started this thread with the hopes of confirming this assumption. The project morphed into a 0.5 way based on sreten's observation that the published Vas of the PE driver is lower than the official Aura specs, and this would make it suitable for a 2-driver design in the same volume.
I though the purpose of the 2nd driver was primarily to reduced (eliminate?) the need for BSC? Perhaps I threw everyone including myself off-track with my question (see above) about the bipole vs front-baffle mount for the 2nd driver and the possible need to attenuate the midrange and high freq. But now I'm back at BSC and rather lost. Am I confusing the BSC calculations with the attenuation of the 2nd driver, and in turn just asking the wrong questions?
I greatly appreciate all the feedback and don't mean to cause frustration for those of you kind enough to help.
Squib
Unfortunately, I'm now quite confused. Let me just back-track for a moment, and please keep in mind that all of this is quite new to me. I have been toying with the idea of a fullrange PC speaker for some time and had originally planned on using zilla's small sealed HiVi B3S design - primarily because of the relative simplicity and low cost. I've been curious as to how good these inexpensive drivers could sound. I subsequently read Zilla's small driver comparison and started to explore the Aura NS3 as another possibility. Timn8er's Aura PC Speaker seemed perfect and something I thought I could manage. However, the Aura's always seem to hover around twice the cost of the HiVi's. There both cheap in the grand scheme of things, but as these speakers will be for my office, and I have a 2nd child on the way, I was still leaning towards the HiVi.
Move forward a couple of weeks...
As I compulsively cruised the PE extended range driver listings I saw an un-named driver that looked like a black-coned NS3 for less than $9. The reviews on the PE site suggested it was in-fact the Aura NS3-193-8a, so I jumped. It was only after I ordered the drivers that I noticed the T/S discrepancies between the PE drivers and the official Aura specs. As Timn8er chose his design so that BSC was not necessary (http://www.diyaudio.com/forums/showthread.php?threadid=51033), I assumed I might just re-dimension his enclosure, keeping the gross volume the same and be safe.
I started this thread with the hopes of confirming this assumption. The project morphed into a 0.5 way based on sreten's observation that the published Vas of the PE driver is lower than the official Aura specs, and this would make it suitable for a 2-driver design in the same volume.
I though the purpose of the 2nd driver was primarily to reduced (eliminate?) the need for BSC? Perhaps I threw everyone including myself off-track with my question (see above) about the bipole vs front-baffle mount for the 2nd driver and the possible need to attenuate the midrange and high freq. But now I'm back at BSC and rather lost. Am I confusing the BSC calculations with the attenuation of the 2nd driver, and in turn just asking the wrong questions?
I greatly appreciate all the feedback and don't mean to cause frustration for those of you kind enough to help.
Squib
You are on the right track. I now did run sims for the box volume with the PE-black NS3 (I own both the PE black coned copy and the real Aura NS3 - there are small dífferences) and you are right that about 4.5 liters works well with two of those drivers in one box. To my eyes the best result comes from tuning to 70Hz, which gives f3 at 60Hz and f10 at 50Hz. Should be fine for pc-speakers. The vent should be D= 1.5" and L= 5.0" (although in many cases calculators give slightly too long vents, so I'd try with something between 3.5" and 4.5"). All this is based on the assumption that the given T/S are correct.
Hi,
IMO a bass tuning lower than 70Hz is the best compromise, as the
bass will quickly overload below the tuning frequency, ideally I'd
go lower than 55Hz tuning but it seems the best compromise.
Note that the main point of using two drivers is really power handling.
Driven flat due to the siting the BSC of a 0.5 way near field may be too
much, but as its a PC speaker thaat does not matter. You should use
some form of PC EQ for fine tuning, by ear with pink noise bands.
You should also use PC EQ to suppress low bass below port tuning.
For the same reasons as above, PC EQ, you can use a single driver,
but as shown the bass peak is "peaky", more difficult to correct.
/sreten.
IMO a bass tuning lower than 70Hz is the best compromise, as the
bass will quickly overload below the tuning frequency, ideally I'd
go lower than 55Hz tuning but it seems the best compromise.
Note that the main point of using two drivers is really power handling.
Driven flat due to the siting the BSC of a 0.5 way near field may be too
much, but as its a PC speaker thaat does not matter. You should use
some form of PC EQ for fine tuning, by ear with pink noise bands.
You should also use PC EQ to suppress low bass below port tuning.
For the same reasons as above, PC EQ, you can use a single driver,
but as shown the bass peak is "peaky", more difficult to correct.
/sreten.Attachments
Sorry for the delay in my response. After a little more time with WinSID, I'm inclined to agree with sreten as far as the port tuning. For my purposes, I think a tuning close to the originally-planned 60hz will allow for relatively flat response after some minor EQ tweaking. Although it's not the prettiest response plot, this arrangement seems to be the best compromise I can squeeze out of the basic enclosure I have planned. I
Attachments
revised sketch
Here's what I'm hoping will be the final design. The drivers will be mounted to the back side of the front baffle. The driver cut-outs will be rounded over (1/2" radius). I'll be working on these over the next couple of weekends and will be posting some photos. Thanks again for your help Timn8er, sreten, and Landroval!
Here's what I'm hoping will be the final design. The drivers will be mounted to the back side of the front baffle. The driver cut-outs will be rounded over (1/2" radius). I'll be working on these over the next couple of weekends and will be posting some photos. Thanks again for your help Timn8er, sreten, and Landroval!
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