Hello DIYers! I was hoping to get some help with a DIY speaker project for myself.
Some background: I already have a nice stereo in the lounge room. This system is in the neutral/analytical camp. I really like that sound signature but I want to build something at least a little bit different for this system.
I’m out of work due to illness and going more than a little bit crazy due to boredom. So I’m starting up a project to hopefully give me some fulfillment. I want to keep the project under $500 as I don’t have a source of income right now. I’m getting a little money from friends as a birthday gift and I have to cover the rest. Due to the illness I’m also suffering some mild mental impairment so I don’t want to make the project too ambitious. Hopefully I can get some help from you guys along the way too.
I’ve previously built some a pair of 2 way bookshelves and an MTM center from Troels Gravesen’s design (Vifa PL14WJ-). These speakers now live with my parents and I was happy with the results. I used preconstructed cabinets so did not do any of the woodwork. I did install the parts, dampen the cabinets, and build the crossovers. I’d like to go a bit deeper this time and design more of the system myself. I have no experience with woodwork but have a helper with experience and tools.
Requirements:
Preferences:
Initial Ideas:
Are there any good beginner resources that would help me quickly learn about:
Thanks for your help!
Some background: I already have a nice stereo in the lounge room. This system is in the neutral/analytical camp. I really like that sound signature but I want to build something at least a little bit different for this system.
I’m out of work due to illness and going more than a little bit crazy due to boredom. So I’m starting up a project to hopefully give me some fulfillment. I want to keep the project under $500 as I don’t have a source of income right now. I’m getting a little money from friends as a birthday gift and I have to cover the rest. Due to the illness I’m also suffering some mild mental impairment so I don’t want to make the project too ambitious. Hopefully I can get some help from you guys along the way too.
I’ve previously built some a pair of 2 way bookshelves and an MTM center from Troels Gravesen’s design (Vifa PL14WJ-). These speakers now live with my parents and I was happy with the results. I used preconstructed cabinets so did not do any of the woodwork. I did install the parts, dampen the cabinets, and build the crossovers. I’d like to go a bit deeper this time and design more of the system myself. I have no experience with woodwork but have a helper with experience and tools.
Requirements:
- Small desktop speakers to be used at my computer. No larger than 5” drivers (slight preference for 4” if an appropriate driver can be found).
- I will likely build stands to raise and/or angle them towards ear level.
- 2.0 system with no sub at this stage.
- Budget to not exceed $500 including drivers, electronics, cabinets, and shipping to Australia (will likely be $100)
Preferences:
- I like detail but I am very susceptible to listening fatigue. So happy to trade for a smoother more listenable presentation.
- I love mids so the midwoofer would have to perform well here.
- I hate bloated bass. I would rather have lean bass than uncontrolled bass. Not expecting much extension given the size limitations but it would be nice to get something that has a nice mid-bass punch in it still.
Initial Ideas:
- 2 way active speakers with a digital crossover. Using a Mini DSP (MiniDSP kit | MiniDSP) and a cheap 4 channel amp (e.g. Lepai LP-269FS 4x45W Mini Amplifier with Remote USB MP3 Media Card FM). I like the ideas of the DSP because it will let me do some more hands on learning where I can tweak crossover values and see how it changes the sound without having to swap parts in and out. I should be able to borrow some measuring equipment from a friend.
- A “novel” driver technology. I was thinking ribbons, planar, or AMT tweeter. Then using a conventional midwoofer unless there are some novel things to try here as well.
- Recommended drivers?
- Other alternatives to try?
- Open Baffle feasible? They will be close to the back wall and it looks like most tweeters are closed backed so I would need to buy a 2nd rear facing pair which would blow my meagre budget out of the water. I also expect the bass would be further underwhelming.
- I have no experience with tubes or high efficiency so was thinking of that as an option. But it seems like this would be too bulky and expensive for my needs. Especially if I was actively amping them. Any opinions here?
Are there any good beginner resources that would help me quickly learn about:
- Driver matching. Parameters, crossover points, etc…
- Crossover design
- Enclosure design
- Cabinet building
Thanks for your help!
For a smallcomputer near-field speaker, a 1-qat system has some distinct advantages. Have a look at the Mark Audio Alpair 7.3
dave
dave
Tumble,
Drivers for high quality desktop solution:
https://www.parts-express.com/peerless-830870-4-ppb-cone-hds-woofer--264-1070
https://www.parts-express.com/dayton-audio-dc28f-8-1-1-8-silk-dome-tweeter--275-070
In a 5 litre vented box. XO filter should be designed with measurement gear.
Wish you a fast recovery.
Drivers for high quality desktop solution:
https://www.parts-express.com/peerless-830870-4-ppb-cone-hds-woofer--264-1070
https://www.parts-express.com/dayton-audio-dc28f-8-1-1-8-silk-dome-tweeter--275-070
In a 5 litre vented box. XO filter should be designed with measurement gear.
Wish you a fast recovery.
I converted a Videotone MiniMax to active using LR4 active crossovers to the attached chipamp hanging on the backpanel.
No EQ, or other corrections, yet.
Plays quite nicely.
The two channel chipamps in each speaker are set with Mid & Upper Bass 150Hz to 2700Hz 4pole and the treble 2700Hz (4pole) to RF filter (160kHz single pole).
The 15" Bass only is also LR4 @ 150Hz under the desk. All 5 channels are ~50W and is more than plenty
No EQ, or other corrections, yet.
Plays quite nicely.
The two channel chipamps in each speaker are set with Mid & Upper Bass 150Hz to 2700Hz 4pole and the treble 2700Hz (4pole) to RF filter (160kHz single pole).
The 15" Bass only is also LR4 @ 150Hz under the desk. All 5 channels are ~50W and is more than plenty
Do give a thought to a fullrange driver, they are at their best used nearfield and are simply pretty damn good.
Regardless of your choosing 1 or 2-way, sounds like a driver that can work in a sealed enclosure would be good for you, according to your bass preference. It would be fairly easy to implement such a scheme at least, as sealed box are more forgiving. If you can get f3<80Hz and Qtc~0.7, desktop placement, especially combined to a rear wall, can take away the need for BSC and provide a quasi quarter-space spatial load if you're sitting right there. Smooth and (relatively) extended low-end should ensue. 🙂 If a specific driver does not get low enough an f3 with a reasonable Qtc, Linkwitz Transform can always be applied via miniDSP. Just don't go nuts trying to take it to f3<40Hz, you'll kill all amp headroom and power handling. 😉
OTOH, a very well damped vented alignment can also work as good a sealed in such a situation, with possibly a tad more extension and lower cone excursion. You could high-pass the driver where it becomes unloaded below port tuning, where the response is already too far down to really hear anyway.
Regardless of your choosing 1 or 2-way, sounds like a driver that can work in a sealed enclosure would be good for you, according to your bass preference. It would be fairly easy to implement such a scheme at least, as sealed box are more forgiving. If you can get f3<80Hz and Qtc~0.7, desktop placement, especially combined to a rear wall, can take away the need for BSC and provide a quasi quarter-space spatial load if you're sitting right there. Smooth and (relatively) extended low-end should ensue. 🙂 If a specific driver does not get low enough an f3 with a reasonable Qtc, Linkwitz Transform can always be applied via miniDSP. Just don't go nuts trying to take it to f3<40Hz, you'll kill all amp headroom and power handling. 😉
OTOH, a very well damped vented alignment can also work as good a sealed in such a situation, with possibly a tad more extension and lower cone excursion. You could high-pass the driver where it becomes unloaded below port tuning, where the response is already too far down to really hear anyway.
I'm definitely a fan of a sealed boxes. I like their bass presentation much better. Will I still have enough extension in a sealed box to get that mid bass punch? Does anyone know what frequency range that occupies? From memory it was in the 60-100 Hz range. I'm talking about the kind you feel in your chest vs. the low bass rumble you feel all over.
Full rangers are definitely an option but I'm leaning away from them for a few reasons: in my experience I have found they cause listening fatigue quite quickly for my ears. I suspect this is due to cone breakup and IMD from running a driver through such a large range. I've found that my ears generally respond better to multiway systems. The Mark Audio driver mentioned also had recessed mids with some peaks in the upper frequency which without hearing them personally would guess they wouldn't match my sonic preferences. Lastly, I'm steering away from fullrangers because there are less toys for me to play with when building a singleway 😛
IG81, could you please simplify some of your comments? I understand the conclusions you reached but the tech specs and implementation to get there was over my head.
Full rangers are definitely an option but I'm leaning away from them for a few reasons: in my experience I have found they cause listening fatigue quite quickly for my ears. I suspect this is due to cone breakup and IMD from running a driver through such a large range. I've found that my ears generally respond better to multiway systems. The Mark Audio driver mentioned also had recessed mids with some peaks in the upper frequency which without hearing them personally would guess they wouldn't match my sonic preferences. Lastly, I'm steering away from fullrangers because there are less toys for me to play with when building a singleway 😛
IG81, could you please simplify some of your comments? I understand the conclusions you reached but the tech specs and implementation to get there was over my head.
Given how open my initial request was how about we take this more narrow approach:
Can someone please help me pick out a novel/exotic driver: ribbons, planar, electrostat, or AMT tweeter?
Once I've decided on one we can then work on finding a woofer that matches.
Thanks!
Can someone please help me pick out a novel/exotic driver: ribbons, planar, electrostat, or AMT tweeter?
Once I've decided on one we can then work on finding a woofer that matches.
Thanks!
See if anything here can help you learn a few things - The Speaker Building Bible
That Fountek could be a reasonable tweeter choice although it needs to be crossed over somewhere around 3.5-4kHz (distortion is rising below that). So in terms of a 2-way that can also reach low without a sub, matching a small mid/woofer to it might be challenging. Usually you are more likely to see ribbon tweeters like that in a 3-way where you can use a smaller mid for the high xo point and then also have a larger woofer to hit the low notes, or a smaller 2-way with a sub.
It will probably help if you can refine your design criteria just a bit more so that we know your maximum box volume (5L, 10L, 15L ?), your desired F3, max SPL and nominal impedance.
For small drivers with quite good sound quality that can also go low and are relatively inexpensive, you might take a closer look at the Dayton ND series of drivers. The ND105-4 has an F3 of 42Hz in 7L ported. You could probably cross that over to the Fountek at about 3000Hz or so. The little ND91-8 will do 60Hz in less than 2L ported. You could do 2 of those in less than 5L for more SPL's and easily cross to that ribbon tweeter. But in both of those cases, your amp has to be happy with 4ohm loads.
With the ND140-8, you can get an F3 of 40Hz in 15L ported and an F3 of 70Hz in 7L sealed but I think you're looking at a lower xo point with that one, maybe 2-2.5Khz.
That Fountek could be a reasonable tweeter choice although it needs to be crossed over somewhere around 3.5-4kHz (distortion is rising below that). So in terms of a 2-way that can also reach low without a sub, matching a small mid/woofer to it might be challenging. Usually you are more likely to see ribbon tweeters like that in a 3-way where you can use a smaller mid for the high xo point and then also have a larger woofer to hit the low notes, or a smaller 2-way with a sub.
It will probably help if you can refine your design criteria just a bit more so that we know your maximum box volume (5L, 10L, 15L ?), your desired F3, max SPL and nominal impedance.
For small drivers with quite good sound quality that can also go low and are relatively inexpensive, you might take a closer look at the Dayton ND series of drivers. The ND105-4 has an F3 of 42Hz in 7L ported. You could probably cross that over to the Fountek at about 3000Hz or so. The little ND91-8 will do 60Hz in less than 2L ported. You could do 2 of those in less than 5L for more SPL's and easily cross to that ribbon tweeter. But in both of those cases, your amp has to be happy with 4ohm loads.
With the ND140-8, you can get an F3 of 40Hz in 15L ported and an F3 of 70Hz in 7L sealed but I think you're looking at a lower xo point with that one, maybe 2-2.5Khz.
I haven't got access to my computer atm but I believe this SB works well in around a 7l enclosure.
The Madisound Speaker Store
Another option is this audax which looks like it can be crossed over relatively high, but is quite expensive and not the best on the low end.
The Madisound Speaker Store
The Madisound Speaker Store
Another option is this audax which looks like it can be crossed over relatively high, but is quite expensive and not the best on the low end.
The Madisound Speaker Store
jReave. That Speaker Building Bible guide was pretty much exactly what I was looking for. Thanks for linking that through.
Some more design criteria:
Thanks for everyone's help so far! Already learning a lot and having some good fun looking at all of the options.
Some more design criteria:
- Near-field listening only. Approx 70cm away from speakers.
- Normal listening levels are 70-80db. The ability to occasionally hit 90 without too much distortion would be nice but not necessary.
- The 4 channel amps I was looking at were 2ohm stable so should be OK with a 4ohm load.
- The speakers will be on a desk against the wall. So bass loading from the table surface and wall would apply. I would like my F3 to be generous enough to still provide that mid-bass chest punch. Would the 80Hz recommended by IG81 work or should I aim more for the 50-60Hz range?
- The previous speakers I built for my dad were in an 11 Litre box. That is definitely way too big for my desk. Doing some rough guessing with a measuring tape I think a 7 litre box would be workable but a 5 litre box would be more convenient (only if I don't have to trade too much performance).
- I looked into the amps I was thinking of a little more closely. And unfortunately they only had a single L and R input even though they have 2 L and R outputs. If I go active with the mini DSP I will have 2 L outputs and 2 R outputs. So would need an amp with 4 inputs and 4 outputs. Any recommendations? I'm going to start looking for second hand pro amps locally. Are there other cheap options? Perhaps even in the DIY realm?
- Will the proposed solution with a wideband mid-bass driver make some compromises in midrange performance? If I like midrange should I abandon the idea of ribbon tweeters in a 2 way?
- Are there any other suitable ribbon/AMT/planar/etc drivers out there? Is the prime criteria for one of these drivers in a 2 way that it has a lower acceptable crossover point before distortion steps in?
- What are the best ways to analyse the available driver options? Look at the frequency graphs to see performance + look at the waterfall graphs to see distortion and resonance over these frequency ranges? Are these only available from the manufacturer's website? I can't seem to find this detailed info on Parts Express.
Thanks for everyone's help so far! Already learning a lot and having some good fun looking at all of the options.
A ring radiator may be another option if you wanted to keep away from dome tweeters. They are a bit more difficult to crossover.
Vifa XT25SC90-04 1" Dual Ring Radiator Tweeter
Vifa XT25SC90-04 1" Dual Ring Radiator Tweeter
You might find 80Hz to be sufficient but 60Hz I think would be better. A dB or 2 boost in that under 100Hz region is often used to give the illusion of a little bit more bass extension and you can do this with either eq or with how you tune a vented box. Whether you go sealed or vented is going to depend on driver choice I think.
Depends on the driver. I kind of missed your preference for very good midrange when I suggested the ND drivers - they do great down low but at least for the ND91-8's that I'm familiar with, I would call the midrange pretty good but not outstanding. One way to stick with the ND drivers is to use a smaller full range driver with it instead of a tweeter. Like say 2" or 3" and cross it say somewhere around 500-700Hz. For eg, I tried it with the little Fountek FR58EX 2" driver and quite like it. Two other high quality ones to consider without a tweeter are:
Fountek-FR88EX
Vifa-TC9FD
No. The next drivers I was going to suggest are what theyoungone suggested - the 4" (well, really 5" outside diameter) SB drivers. Excellent midrange, will play low vented in small volumes and will cross high enough for a ribbon tweeter. That would be quite a nice speaker I think. It won't play really loud but that won't be a problem for you and actually you can high pass it down around 40Hz-50Hz with the dsp where the excursion can start to get excessive.
I'd say distortion, power handling and cost are the important factors. Vertical dispersion as well but that shouldn't be a problem for nearfield computer speakers. The other big name in 'exotic' drivers is BG planars . I don't think that the Neo3 tweeter is worth it for you but you might consider the Neo8 as a mid/tweeter paired with one of the Dayton ND's. It's got something of a challenging FR and most people pair it with a tweeter, but I have seen one person use it before full range from about 600Hz and up. Very clean, very detailed and very 'fast' but I'm figuring that's going to blow your budget. 🙁
Yes, but good user responses don't hurt either. Look at Zaphaudio in his driver shootouts and in his Blog too for more measurements than you'll be able to keep straight.
Sorry, I don't know much about active set-ups and amps although I do know that you can configure some AVR receivers to make them work.
jReave! Delivering again! Thanks so much for that detailed response, you've been super helpful! I've got a whole new set of questions again if you don't mind.
I've decided to break the budget already and spring for the NEO 8's 😀
The peak at 12-15k will give me a good lesson in notch filters. I did some light reading on these drivers and it seems like other than that spike in response the drivers are otherwise good to run in this range. Is there any distortion or other nastiness that you know of that comes with this frequency spike? Or can some EQ sort it all out for me? The limited vertical dispersion is a plus for my desktop and nearfield listening setup as it will help reduce first reflections off the desk.
As for the amps I've figured out I can use a separate two channel amp for each speaker. The miniDSP I will be getting that goes in front of the amps has a volume control so it will be my pre.
Now on to woofer matching. I read through Zaph's comparisons and found that equal parts enlightening and equal parts confusing. Despite a few that were poor performers most measurements looked rather similar. It looks like the test has dated a bit as I was unable to find the two that appealed to me the most the Vifa PL11 and the Seas L12.
I also did some quick shipping calculation on Parts Express and Madisound. To keep costs down I'm going to have go for a single order on Parts Express so will have to limit myself to stock they carry.
I've started to dig into the T/S parameters and am understanding most of it so far. I've been using Speaker Box Enclosure Designer / Calculator Where I've gotten stuck is on Vb. Should you always build the volume box recommended by Vb? I was under the impression that adding more volume was always beneficial.
The calculations I'm running through there also don't match up with yours. For instance when I plug in the parameters for the Dayton ND105-4 I'm getting an F3 of 34.3 Hz and a recommended box volume of 12.6 L and you mentioned "F3 of 42Hz in 7L". How did you get your calculations? Will changing the volume change the F3? If so will it change anything else for better or worse? What's a good calculator I can use to figure out your calculations?
Any other recommended bass drivers to go with the Neo8? I like the idea of having wideband drivers on top and bottom because that will let me play around a lot with the crossover points and slopes so I can learn about driver blending and characteristics. However, if there is a more solid bass only candidate I'd also take that into consideration.
Using the port or sealed calculated Sealed or Ported Enclosure Calculator it says that the class of drivers we're looking at are recommended for ported use only. As they will be close to the wall front-ported would be necessary. Adding a front port is going to make these a really tall speaker! Would these drivers still perform OK in a sealed box? Using the Dayton ND105-4 in a sealed box gives a F3 of 69hz and box size of 7 litres. Which otherwise fits my specs pretty well.
How does using 2 drivers work? I understand it would reduce the load on each driver giving you more output, it would also halve the impedance, and you would have cleaner output as you are not pushing the drivers as hard. Would it impact extension much? How does it impact box size calculations? Would 2 ND105-4s ($25*2) be outperformed by a single more expensive $50 driver?
Thanks again everyone for your help, advice, and info!
I've decided to break the budget already and spring for the NEO 8's 😀
The peak at 12-15k will give me a good lesson in notch filters. I did some light reading on these drivers and it seems like other than that spike in response the drivers are otherwise good to run in this range. Is there any distortion or other nastiness that you know of that comes with this frequency spike? Or can some EQ sort it all out for me? The limited vertical dispersion is a plus for my desktop and nearfield listening setup as it will help reduce first reflections off the desk.
As for the amps I've figured out I can use a separate two channel amp for each speaker. The miniDSP I will be getting that goes in front of the amps has a volume control so it will be my pre.
Now on to woofer matching. I read through Zaph's comparisons and found that equal parts enlightening and equal parts confusing. Despite a few that were poor performers most measurements looked rather similar. It looks like the test has dated a bit as I was unable to find the two that appealed to me the most the Vifa PL11 and the Seas L12.
I also did some quick shipping calculation on Parts Express and Madisound. To keep costs down I'm going to have go for a single order on Parts Express so will have to limit myself to stock they carry.
I've started to dig into the T/S parameters and am understanding most of it so far. I've been using Speaker Box Enclosure Designer / Calculator Where I've gotten stuck is on Vb. Should you always build the volume box recommended by Vb? I was under the impression that adding more volume was always beneficial.
The calculations I'm running through there also don't match up with yours. For instance when I plug in the parameters for the Dayton ND105-4 I'm getting an F3 of 34.3 Hz and a recommended box volume of 12.6 L and you mentioned "F3 of 42Hz in 7L". How did you get your calculations? Will changing the volume change the F3? If so will it change anything else for better or worse? What's a good calculator I can use to figure out your calculations?
Any other recommended bass drivers to go with the Neo8? I like the idea of having wideband drivers on top and bottom because that will let me play around a lot with the crossover points and slopes so I can learn about driver blending and characteristics. However, if there is a more solid bass only candidate I'd also take that into consideration.
Using the port or sealed calculated Sealed or Ported Enclosure Calculator it says that the class of drivers we're looking at are recommended for ported use only. As they will be close to the wall front-ported would be necessary. Adding a front port is going to make these a really tall speaker! Would these drivers still perform OK in a sealed box? Using the Dayton ND105-4 in a sealed box gives a F3 of 69hz and box size of 7 litres. Which otherwise fits my specs pretty well.
How does using 2 drivers work? I understand it would reduce the load on each driver giving you more output, it would also halve the impedance, and you would have cleaner output as you are not pushing the drivers as hard. Would it impact extension much? How does it impact box size calculations? Would 2 ND105-4s ($25*2) be outperformed by a single more expensive $50 driver?
Thanks again everyone for your help, advice, and info!
a sealed box loading directly sets the speaker Q.
A smaller box volume gives a higher Q.
too small a box leads to a high Q that gives that typical "one note" humped response bass that drones away and makes for poor intelligibility.
An optimised box volume can give very good intelligibility and some bass extension.
Very low bass extension is impossible, unless you add EQ, for example Linkwitz Transform.
A smaller box volume gives a higher Q.
too small a box leads to a high Q that gives that typical "one note" humped response bass that drones away and makes for poor intelligibility.
An optimised box volume can give very good intelligibility and some bass extension.
Very low bass extension is impossible, unless you add EQ, for example Linkwitz Transform.
A sealed box makes the inside pressure modulate the movement.
It is in part wanted, just because it acts like a spring.
The speaker itself got to be projected for the duty.
The bad part is that the membrane is transparent to the low tones...
I dunno why it has some preference amongst...humans ??!
It is in part wanted, just because it acts like a spring.
The speaker itself got to be projected for the duty.
The bad part is that the membrane is transparent to the low tones...
I dunno why it has some preference amongst...humans ??!
After a bit more reading, it looks like resonances up high on the Neo8 are certainly not a problem and that distortion probably isn't. However, horizontal off-axis suffers a little above 7kHz so for you I'd move over to the Neo8PDR which is better in this regard.
In terms of the woofer, don't even bother with those types of calculators - even if they are correct in terms of F3, Vb, etc, they don't give you enough information to make good decisions with. Besides understanding the relationships between Vb, F3, Qtc for sealed boxes and Fb and port tuning for vented boxes, you also need to understand the relationships between max SPL, max cone excursion and max vent air velocities. Sounds complicated, I know, but it's easier to get a handle on with a good box simulation program.
I use Unibox, but it requires Excel like much of the good free software out there. WinISD I don't find as easy to use but is comparable and doesn't need Excel. If you can download one of those and start playing around with it, that may answer a number of your questions - or perhaps it will just raise some more. 😀 But you'll be further ahead in any event.
In terms of Zaph's measurements, finding drivers that measure well is just the start - then they have to fit the rest of your design criteria. So the distortion on the Seas and the Vifa look good but I don't think they will hit your F3 or Vb requirements let alone price and/or availability.
In terms of Vb, every driver sort of has an ideal tuning in both a sealed or vented box but these can be easily changed to suit your needs, within reason. So for you, one of your top criteria is size limitation, ie. 5 - 7L. So what you should be looking for is, what is the best response I can get out of a driver in this size box? How low can you get it and how loud will it go at that lowest frequency before xmax is exceeded or the vent starts chuffing? (xmax is max excursion before distortion starts to increase because the voice coil starts to move beyond the magnet. Note that typically the cone can still physically move further and so can still play louder but not as cleanly)
So, 1st chart below shows the ND105-4 in different vented alignments. Notice that as we lower the Vb from 12L to 7L to 5L that we also have to increase the tuning frequency, Fb, to get a good FR although the response is still rising below 200Hz, but as I said before a dB or 2 increase there may actually be a good thing. More than that - probably not.
Now lets look at xmax, max SPL and vent velocity. With that driver, xmax is 4mm although its mechanical limit is 10mm one way. The 2nd chart shows you the cone excursion for the 7L example with 8W giving you about 92dB at 1m which is going to be your max (clean) SPL because you can see that at about 70Hz, the cone is just under its xmax. Below 45Hz though, xmax is easily exceeded except this doesn't matter that much because 1) music doesn't have a lot of content below 40Hz, 2) the driver is in no danger because mechanical excursion is not exceeded, and 3) with dsp you can sharply filter out anything below about 40 or 50Hz anyways.
Next chart shows the vent velocity however and at these SPL's, the red lin is exceeded so there's a good chance that it's going to chuff. To fix this you need to make the port wider (I had chosen 3cm) but to keep the same tuning, that means it also has to be longer and now that will take up a little bit more internal volume so now you need a wee bit bigger box too. So those are sort of all the things you have to consider with a vented box.
If you went sealed in 4L with the same 8W you get the next 2 charts. F3 is only 75Hz this time and xmax is just very slightly exceeded but here's what you want to really look at: at 60 Hz your max SPL is going to be about 86dB. Why is this important? Because you can boost that response from 60 - 100Hz with dsp or eq (or drop the whole response above 100Hz I guess) but you still don't really won't to be exceeding xmax at those lowest frequencies if you don't have to. Just so you know, that's 86dB for 1 speaker. Adding a 2nd speaker adds another 6dB to the total output so you would still get your max 90dB levels cleanly in this example.
Now don't forget also that your box has to include space for the Neo8, I'd say probably about 1-1.5L may do it but I'm guessing because a driver like that doesn't have TS parameters, so you're going to be looking at less than 7L for the woofer. I'd try for 4 or 5L myself.
With 2 drivers btw, Vb needs to be doubled but F3 stays the same. You are correct about everything else. But will 1 more expensive driver be better? Depends on the driver. And it depends on what criteria you may be looking at. It's not always true that more $ = better quality but sometimes you do get what you pay for. But I don't think you have space for 2 drivers unless they are the ND91-8's.
Ok, that's probably a lot of info to take in. 😉
My preferences so far would be these:
One of the SB 12 series
ND105-4
Peerless SDS 4"
And maybe try one of these Aussie dealers to compare prices:
https://www.wes.com.au/
theloudspeakerkit
In terms of the woofer, don't even bother with those types of calculators - even if they are correct in terms of F3, Vb, etc, they don't give you enough information to make good decisions with. Besides understanding the relationships between Vb, F3, Qtc for sealed boxes and Fb and port tuning for vented boxes, you also need to understand the relationships between max SPL, max cone excursion and max vent air velocities. Sounds complicated, I know, but it's easier to get a handle on with a good box simulation program.
I use Unibox, but it requires Excel like much of the good free software out there. WinISD I don't find as easy to use but is comparable and doesn't need Excel. If you can download one of those and start playing around with it, that may answer a number of your questions - or perhaps it will just raise some more. 😀 But you'll be further ahead in any event.
In terms of Zaph's measurements, finding drivers that measure well is just the start - then they have to fit the rest of your design criteria. So the distortion on the Seas and the Vifa look good but I don't think they will hit your F3 or Vb requirements let alone price and/or availability.
In terms of Vb, every driver sort of has an ideal tuning in both a sealed or vented box but these can be easily changed to suit your needs, within reason. So for you, one of your top criteria is size limitation, ie. 5 - 7L. So what you should be looking for is, what is the best response I can get out of a driver in this size box? How low can you get it and how loud will it go at that lowest frequency before xmax is exceeded or the vent starts chuffing? (xmax is max excursion before distortion starts to increase because the voice coil starts to move beyond the magnet. Note that typically the cone can still physically move further and so can still play louder but not as cleanly)
So, 1st chart below shows the ND105-4 in different vented alignments. Notice that as we lower the Vb from 12L to 7L to 5L that we also have to increase the tuning frequency, Fb, to get a good FR although the response is still rising below 200Hz, but as I said before a dB or 2 increase there may actually be a good thing. More than that - probably not.
Now lets look at xmax, max SPL and vent velocity. With that driver, xmax is 4mm although its mechanical limit is 10mm one way. The 2nd chart shows you the cone excursion for the 7L example with 8W giving you about 92dB at 1m which is going to be your max (clean) SPL because you can see that at about 70Hz, the cone is just under its xmax. Below 45Hz though, xmax is easily exceeded except this doesn't matter that much because 1) music doesn't have a lot of content below 40Hz, 2) the driver is in no danger because mechanical excursion is not exceeded, and 3) with dsp you can sharply filter out anything below about 40 or 50Hz anyways.
Next chart shows the vent velocity however and at these SPL's, the red lin is exceeded so there's a good chance that it's going to chuff. To fix this you need to make the port wider (I had chosen 3cm) but to keep the same tuning, that means it also has to be longer and now that will take up a little bit more internal volume so now you need a wee bit bigger box too. So those are sort of all the things you have to consider with a vented box.
If you went sealed in 4L with the same 8W you get the next 2 charts. F3 is only 75Hz this time and xmax is just very slightly exceeded but here's what you want to really look at: at 60 Hz your max SPL is going to be about 86dB. Why is this important? Because you can boost that response from 60 - 100Hz with dsp or eq (or drop the whole response above 100Hz I guess) but you still don't really won't to be exceeding xmax at those lowest frequencies if you don't have to. Just so you know, that's 86dB for 1 speaker. Adding a 2nd speaker adds another 6dB to the total output so you would still get your max 90dB levels cleanly in this example.
Now don't forget also that your box has to include space for the Neo8, I'd say probably about 1-1.5L may do it but I'm guessing because a driver like that doesn't have TS parameters, so you're going to be looking at less than 7L for the woofer. I'd try for 4 or 5L myself.
With 2 drivers btw, Vb needs to be doubled but F3 stays the same. You are correct about everything else. But will 1 more expensive driver be better? Depends on the driver. And it depends on what criteria you may be looking at. It's not always true that more $ = better quality but sometimes you do get what you pay for. But I don't think you have space for 2 drivers unless they are the ND91-8's.
Ok, that's probably a lot of info to take in. 😉
My preferences so far would be these:
One of the SB 12 series
ND105-4
Peerless SDS 4"
And maybe try one of these Aussie dealers to compare prices:
https://www.wes.com.au/
theloudspeakerkit
Attachments
Last edited:
The left pic shows a humped bass response for all three sizes of boxes. This tells you that Qbox is > 0.7
I find this type of alignment gives boomy bass. I am forever looking for new speaker locations to minmise that "boominess".
I end up not listening to that speaker, or not buying it at audition.
I much prefer a Qbox < 0.7
A couple of members directed me towards a Bessel type alignment (q~0.6)
I have never looked back. Boominess gone. Male vocal, in particular speech is very natural. All voices are intelligible.
I cannot recommend the bass that comes out of "too small" boxes.
I find this type of alignment gives boomy bass. I am forever looking for new speaker locations to minmise that "boominess".
I end up not listening to that speaker, or not buying it at audition.
I much prefer a Qbox < 0.7
A couple of members directed me towards a Bessel type alignment (q~0.6)
I have never looked back. Boominess gone. Male vocal, in particular speech is very natural. All voices are intelligible.
I cannot recommend the bass that comes out of "too small" boxes.
I find it depends on what the tuning is. I don't think I can say this any better than Jeff B has:
" One of the things I have learned over the years concerns the relationship between the room, the speaker’s F3, bass tuning, and our perception of the bass response. I have found that when speaker roll-off in the 100 – 70Hz range a small hump of 2-3db just above the roll-off frequency can make the speaker sound more balanced and even more extend. This is the same thing Harwood did at the BBC in designing the LS3/5a. But if a speaker extends into the 50Hz range then a little hump works best, one of only 1-2dB. If a speaker extends to 40 Hz or so then it sounds the most balanced if it is as flat as possible. And finally, if a speaker extends below 30hz, and especially if it reaches 20Hz, then an over damped response with a gentle drooping at the bottom end sounds the most balanced in most rooms due to room pressurization gain. "
But in addition to that, in this instance the speaker can be eq'd to suit anyways.
" One of the things I have learned over the years concerns the relationship between the room, the speaker’s F3, bass tuning, and our perception of the bass response. I have found that when speaker roll-off in the 100 – 70Hz range a small hump of 2-3db just above the roll-off frequency can make the speaker sound more balanced and even more extend. This is the same thing Harwood did at the BBC in designing the LS3/5a. But if a speaker extends into the 50Hz range then a little hump works best, one of only 1-2dB. If a speaker extends to 40 Hz or so then it sounds the most balanced if it is as flat as possible. And finally, if a speaker extends below 30hz, and especially if it reaches 20Hz, then an over damped response with a gentle drooping at the bottom end sounds the most balanced in most rooms due to room pressurization gain. "
But in addition to that, in this instance the speaker can be eq'd to suit anyways.
Thanks again everyone for the info. Especially to jReave. Going above and beyond providing those charts helped me work my through Unibox easily.
I really had fun playing around with Unibox. I got a much better understanding of what all the parameters are, how they are related, and how they impact performance in a box. I'm itching to get some boxes made up and do some driver testing now. The DIY bug has already bitten hard 😀. When I get back to work I'm definitely going to be investing in a few more drivers to see what the changes I've been modelling in Unibox sound like in the real world.
Some things I've learned, in small sealed boxes trying to get the bass response I want, xmax is king. So many of the drivers I modeled hit their xmax in the 60-80 hz range. I can also understand why so many designs are ported. Such an easy way to boost bass extension and it also opens a wider variety of drivers into the mix as it's not as taxing on xmax.
Some other things I've been doing:
New questions:
For the 5" drivers I went through Zaph's recommendations and had a small spin myself around Parts Express. My shortlist and summary of the drivers is as follows:
I really had fun playing around with Unibox. I got a much better understanding of what all the parameters are, how they are related, and how they impact performance in a box. I'm itching to get some boxes made up and do some driver testing now. The DIY bug has already bitten hard 😀. When I get back to work I'm definitely going to be investing in a few more drivers to see what the changes I've been modelling in Unibox sound like in the real world.
Some things I've learned, in small sealed boxes trying to get the bass response I want, xmax is king. So many of the drivers I modeled hit their xmax in the 60-80 hz range. I can also understand why so many designs are ported. Such an easy way to boost bass extension and it also opens a wider variety of drivers into the mix as it's not as taxing on xmax.
Some other things I've been doing:
- Modeled all recommended 4" drivers and a couple of others in Unibox.
- Visited a friend with speakers that used 4" bass drivers and had an outside volume of 7.2 litres so the internal would be a bit less than that. That form factor was more than acceptable for my desk. I can even get a little more volume included for the same depth as I'm going to have extra height thanks to the Neo8's.
- I played around with adding a port to the 4" drivers and that got me greedy for some more bass extension.
- I mocked up some rough cabinet front panel sizes based on different configurations of drivers and ports (image attached below). Including using a 5" driver in a sealed cabinet. Due to the rear proximity of the speaker to the wall I went with front ported. The 5" sealed cabinet seemed palatable in comparison. So I made some sample cabinets out of cardboard to test in position on my desk. They are a tad on the big side but they still fit. I talked to my girlfriend about them and she said something like "you love sound, don't compromise, go for the big ones". So I'm going to plow ahead with the 5" drivers in a sealed cabinet, marking scope creep number 2 😎
- I got back onto Zaph Audio for some 5" driver recommendations and modeled all of those and a couple of others I found.
New questions:
- Overall bass output would be determined by the driver's natural roll off (i.e. for the SB12 SB Acoustics :: 4? SB12NRX25-4 it's output is ~83db vs. a normal ~87dB across the rest of it's range so a total roll off of -4dB at 80hz) minus the roll off from box modelling (-4dB at 80hz in my plan) plus any impacts from room gain, plus/minus any effects from exciting room nodes. Is this correct? So I would be looking at -8dB using the SB12 before accounting for room gain and room nodes?
- What approximate gains can I expect from room gain and quarter space loading (even possible semi eight)? I've attached a picture of my desk now. New speakers will be in the same spot as the current speakers.
- Does QTC impact anything other than the frequency response? If I EQ'd out the bump from a design with Q > .7 would it sound the same as a design with a Q = .7? Are other areas like transient response or distortion impacted?
- Some help digesting my driver options or making further 5" driver selection options and matching it to the Neo8 as I'll outline below:
For the 5" drivers I went through Zaph's recommendations and had a small spin myself around Parts Express. My shortlist and summary of the drivers is as follows:
- Midwoofers:
- Dayton RS150-8: not much xmax but volume output still within my requirements. Aggressive natural roll off from driver starting at 150hz would probably make extension a challenge. Not enough xmax to EQ this up either. Otherwise good distortion in bass. Enough extension to play around with higher crossover points.
- SB15: average bass distortion. Models pretty well in the box (.7 Q within my size range) for bass extension. Good mid extension for crossover flexibility. My current pick from this category.
- Tangband W5-1685. Worst bass harmonic distortion of all drivers I looked at. Best mid extension. Modeled the same as the SB15 for bass extension but with a higher Q box.
- Based on my xmax obsession I had a look at a few 5" woofers in this range. The Tangband 1138 SM and 1138SMF particularly. I could not find any plots on the distortion for these drivers. They otherwise performed exceptionally in the bass. Despite their inefficiency, I can come up with the power necessary for them. These were the only drivers where I could get down to 50hz with some content still audible in the 40's. The other downside is that these drivers do not have the mid extension of the class above. I have a soft requirement to have a decent overlap in comfortable frequencies of each driver so I can play around with crossover points and slopes as a learning exercise but I am willing to sacrifice this for better bass. Has anyone had any real experience with these drivers? How do they perform? Do they have decent distortion figures? And lastly do you think I could successfully cross them over at 600-700hz with the Neo8? Plots are here: http://meniscusaudio.com/images/NEO8.pdf and http://www.tb-speaker.com/detail/1208_03/w5-1138sm.htm
- Any other driver recommendations?
- Status
- Not open for further replies.