Im just a learner, and I cant see the specific answer to what I need in the forum, although there are severla posts on the use of Unibox - they dont help me with the specifics I need, probably because Im talking real basic stuff to begin with.
Could someone suggest a link, or help me out with some suggestions please ?
I want to improve and supplement the bass response of my current HiFi (not home theatre) system, by adding a subwoofer.
I want to learn the principles and practicalities of building speakers so I can move on to replace my main speakers.
I want my first DIY loudspeaker to be a reasonable success !
So, I plan to :
design and build a sealed box subwoofer.
I plan to cross it over at around 150Hz to take the load off my main speakers and hopefully improve and deepen the bass.
I plan to drive it with a Rod Elliott 300W sub amp and active crossover.
From reading the forums, the Vifa PL22WR-09/08 8" woofer or PL26WR-09-08 10" seem to be reasonable choices amongst many possibilities.
Ive downloaded Unibox 4v04 and loaded up the correct driver from the database.
Now ! I notice :
For a closed box design Qtc of 0.707, it suggests a 40L box.
Max power input for linear operation is 12.5W. That cant be right surely, or do I misunderstand what its telling me ?
F3 is 53Hz, which seems quite high to me. If I was crossing over at 80Hz, I wouldnt have much range to play with, surely ? Is this going to meet my objectives of a significantly deeper and better bass ?
If not, how do I change my design before I shell out my cash !! ?
My problem is really that Ive never heard the results of theory to know if the above design is even close to achieving what I want. Am I on the right track here, or should I amend the design ?
Any help/advice/suggestions much appreciated
Terry.
Could someone suggest a link, or help me out with some suggestions please ?
I want to improve and supplement the bass response of my current HiFi (not home theatre) system, by adding a subwoofer.
I want to learn the principles and practicalities of building speakers so I can move on to replace my main speakers.
I want my first DIY loudspeaker to be a reasonable success !
So, I plan to :
design and build a sealed box subwoofer.
I plan to cross it over at around 150Hz to take the load off my main speakers and hopefully improve and deepen the bass.
I plan to drive it with a Rod Elliott 300W sub amp and active crossover.
From reading the forums, the Vifa PL22WR-09/08 8" woofer or PL26WR-09-08 10" seem to be reasonable choices amongst many possibilities.
Ive downloaded Unibox 4v04 and loaded up the correct driver from the database.
Now ! I notice :
For a closed box design Qtc of 0.707, it suggests a 40L box.
Max power input for linear operation is 12.5W. That cant be right surely, or do I misunderstand what its telling me ?
F3 is 53Hz, which seems quite high to me. If I was crossing over at 80Hz, I wouldnt have much range to play with, surely ? Is this going to meet my objectives of a significantly deeper and better bass ?
If not, how do I change my design before I shell out my cash !! ?
My problem is really that Ive never heard the results of theory to know if the above design is even close to achieving what I want. Am I on the right track here, or should I amend the design ?
Any help/advice/suggestions much appreciated
Terry.
Unless your listening room is tiny, a 10" subwoofer won't be enough to provide clean, deep, bass. 12" is minimum, a 15" is better or you could go for multiple 12" units.
Remember that Unibox, and most other software, assume purely sinusoidal input/ouput signals. At low frequencies, it really does not take much amp. power to overdrive a subwoofer. Under normal program material, it takes a bit more amp. power to stress a good subwoofer as the whole system has to reproduce complex waveforms. Moreover, most of these software use simple models, which do not account for suspension stiffness and motor non-linearities.
You could either change to a vented-box design or you could go for a Linkwitz-Transformed sealed box using a more capable subwoofer (such as a Shiva, XLS, Tempest etc.)... If you want to have deeper bass. In any case, purchasing a better driver unit would be smart.
Bottom line is buy the best driver unit(s) you can afford and then design-build your box well, but don't lose sleep over fractions of differences between box designs -- your room acoustics will have a greater influence on the sub's sound.
Cheers 🙂
Isaac
Remember that Unibox, and most other software, assume purely sinusoidal input/ouput signals. At low frequencies, it really does not take much amp. power to overdrive a subwoofer. Under normal program material, it takes a bit more amp. power to stress a good subwoofer as the whole system has to reproduce complex waveforms. Moreover, most of these software use simple models, which do not account for suspension stiffness and motor non-linearities.
You could either change to a vented-box design or you could go for a Linkwitz-Transformed sealed box using a more capable subwoofer (such as a Shiva, XLS, Tempest etc.)... If you want to have deeper bass. In any case, purchasing a better driver unit would be smart.
Bottom line is buy the best driver unit(s) you can afford and then design-build your box well, but don't lose sleep over fractions of differences between box designs -- your room acoustics will have a greater influence on the sub's sound.
Cheers 🙂
Isaac
Hi,
That's too high, I'd suggest around 100Hz. Otherwise, too much of the midrange would be played through the subwoofer (and be missing in your midrange speakers). Your system would become too much "room-dependent" and your subwoofer would be localized too easily.
I second Isaac's explanation here, go for something bigger and less expensive. You've got plenty of speakers to choose from.
That's reasonable. What UniBox calculated here is the maximum electrical input power at (and below) the "tuning" frequency. As that's the region, where only the capability of linear and maximum cone excursion are important, the resulting input power is relatively unrelated to the nominal electrical power handling of the speaker.
Anyway, those 12.5W don't represent the usable input power capability over the whole used bandwith (e.g. from 50Hz to 150Hz).
That sounds reasonable too. Don't forget that the frequency where the spl is reduced 3dB (below the average spl above that frequency) is only a mathematical expression of the way the box "fades out" to 0Hz...
E.g. with a vented enclosure you would result in a lower f3, but have a steeper drop to frequencies below, either.
I think You're on the right track, you just started with the wrong driver - and probably higher expectations 😎
I tend to prefer the transformed sealed box, but that's a matter of taste. Such a design would give you better adaptability to the room response (as you would have a filter unit at hand anyway). A vented box would give you quicker, "louder" results, tough.
That's too high, I'd suggest around 100Hz. Otherwise, too much of the midrange would be played through the subwoofer (and be missing in your midrange speakers). Your system would become too much "room-dependent" and your subwoofer would be localized too easily.
I second Isaac's explanation here, go for something bigger and less expensive. You've got plenty of speakers to choose from.
That's reasonable. What UniBox calculated here is the maximum electrical input power at (and below) the "tuning" frequency. As that's the region, where only the capability of linear and maximum cone excursion are important, the resulting input power is relatively unrelated to the nominal electrical power handling of the speaker.
Anyway, those 12.5W don't represent the usable input power capability over the whole used bandwith (e.g. from 50Hz to 150Hz).
That sounds reasonable too. Don't forget that the frequency where the spl is reduced 3dB (below the average spl above that frequency) is only a mathematical expression of the way the box "fades out" to 0Hz...
E.g. with a vented enclosure you would result in a lower f3, but have a steeper drop to frequencies below, either.
I think You're on the right track, you just started with the wrong driver - and probably higher expectations 😎
I tend to prefer the transformed sealed box, but that's a matter of taste. Such a design would give you better adaptability to the room response (as you would have a filter unit at hand anyway). A vented box would give you quicker, "louder" results, tough.
Thankyou very much for both of your replies. That makes sense to me now.
So, point taken on crossing over at 100Hz. Thanks for that.
On the driver size, Id stuck to 12" because my only source of practical guidelines was the LDSG pages which said "you reach a point of diminishing returns once you get much past 12". What that means in real terms I dont know - Im just a beginner !
But I like the idea of bigger and less expensive ?
I would certainly rather try to build a decent subwoofer, so a good driver is definately a criteria. Again I got the "recommendation" (well suggestion) for the Vifa drivers specifically from the LDSG guidelines, and then by finding drivers which I can easily source in Australia (predominantly Vifa and Scanspeak as far as I can tell). Hence the Vifa ones, no other reason (so fairly random really).
The better drivers mentioned below arent listed in LDSG, and without any other reference to them could you suggest specifically which ones, or possibly some good alternates from LDSG that I can try to source ? There may well be a wealth of choices out there, but for a novice that's actually worse unless there are some specific recommendations (preferably that can be easily sourced - ie in Australia) !
In my novice mode, Im not sure what you mean by Transformed box ... I cant readily see a reference to it in Dickason, but it must be there ? Sorry - Im learning still !
After pondering the collective advice, Im now contemplating a sealed box push/pull configuration using ... maybe two 12" (10" ?)drivers ? Maybe that would give me better results, or perhaps that's what you mean by a transformed sealed box ?
FT.
Im getting there, thanks for being patient !
Here are the driver manufacturer guides as per LDSG, as if you hadnt already seen them ! :
--------------------------------------------------------------------------------
Accuton ACI Adire Alcone Apex Jr. ATC ATD Audax Audio Technology Aura Axon
Beyma
Cabasse
Dayton Dynaudio
Eclipse Eminence Eton
Focal
GR Research
Hi-Vi Hiquphon Human
Jordan
Lambda LPG
Madisound Manger McCauley MCM Meniscus Monacor Morel
Peerless PHL
Scan-Speak SCH Seas Skaaning Stryke
TangBand Triangle
Usher
Vifa Visaton Volt
So, point taken on crossing over at 100Hz. Thanks for that.
On the driver size, Id stuck to 12" because my only source of practical guidelines was the LDSG pages which said "you reach a point of diminishing returns once you get much past 12". What that means in real terms I dont know - Im just a beginner !
But I like the idea of bigger and less expensive ?
I would certainly rather try to build a decent subwoofer, so a good driver is definately a criteria. Again I got the "recommendation" (well suggestion) for the Vifa drivers specifically from the LDSG guidelines, and then by finding drivers which I can easily source in Australia (predominantly Vifa and Scanspeak as far as I can tell). Hence the Vifa ones, no other reason (so fairly random really).
The better drivers mentioned below arent listed in LDSG, and without any other reference to them could you suggest specifically which ones, or possibly some good alternates from LDSG that I can try to source ? There may well be a wealth of choices out there, but for a novice that's actually worse unless there are some specific recommendations (preferably that can be easily sourced - ie in Australia) !
In my novice mode, Im not sure what you mean by Transformed box ... I cant readily see a reference to it in Dickason, but it must be there ? Sorry - Im learning still !
After pondering the collective advice, Im now contemplating a sealed box push/pull configuration using ... maybe two 12" (10" ?)drivers ? Maybe that would give me better results, or perhaps that's what you mean by a transformed sealed box ?
FT.
Im getting there, thanks for being patient !
Here are the driver manufacturer guides as per LDSG, as if you hadnt already seen them ! :
--------------------------------------------------------------------------------
Accuton ACI Adire Alcone Apex Jr. ATC ATD Audax Audio Technology Aura Axon
Beyma
Cabasse
Dayton Dynaudio
Eclipse Eminence Eton
Focal
GR Research
Hi-Vi Hiquphon Human
Jordan
Lambda LPG
Madisound Manger McCauley MCM Meniscus Monacor Morel
Peerless PHL
Scan-Speak SCH Seas Skaaning Stryke
TangBand Triangle
Usher
Vifa Visaton Volt
Well, that's a subjective comment, but it's experienced and wise enough that I can't disprove it. I guess they know what they offer, although I don't know LDSG. Go for a 12" if you like it.
Hmmm, okay, I could have explained that a little better, I guess. 😀
As I'm always on a budget, one collects experience and comments/recommendations for cheaper-than-average stuff. There are many suppliers and speaker types which are heavily overpriced. And in the same sense, there are quite a lot which are cheaper than one would expect (always keeping good quality level, of course 😉).
Out of your list, I can recommend some types from Adire, Audax, Beyma, Eton, LPG, Monacor, Peerless, PHL, Seas on Visaton. As you can see, Vifa and Scan-Speak are not among my recommendations, while SEAS and Peerless are (all of them are manufactured in Scandinavia and I like them due to their quality-per-price ratio).
While I don't know some of the manufacturers, I dislike (and don't recommend) others on your list. But as this is something subjective (I'm talking about sound quality here, not about price) you shouldn't take it too serious.
Shure. I didn't want to tell you to go for cheap. But "decent" is no result of marketing or sales price.
No, that was me, cutting too short, again. 😉
A "transformed" box is a box in conjunction with an (active) electrical circuit that works together with the parameters of the box and complements the (active) crossover circuit. Note that you can't use passive crossover techniques here, as low crossover frequence and passive implementation are mutually exclusive with good quality!
This transformation was published by Siegfried Linkwitz. It (sort of) cancels the low cut off that is inherent to the box and introduces a new cut off (which you can choose). The resulting bass frequency response is the one you desire, with the price for the effort being a reduced sensitivity and maximum SPL (just search for "ELF" or "Linkwitz transform").
It's a very good approach, but complicated to implement in case you want to get it done easily...
Oh, and no, Dickason doesn't write about it. 😉
Go for it, I'd say.
But as I've never built a push-pull configuration with powerful drivers, I can't recommend specific drivers and construction plans, sorry.
General considerations:
The enclosure has to be rock-solid, at least 22mm MDF. If it's your first box, go for MDF, as it's easy to work with and cheap enough to afford a rebuild after leaving the prototype stage. 😀
Depending on enclosure size, brace the volume (directly) between the driver baffles, as higher excursion levels could let the walls resonate and swing out of phase (resulting in bad to poor bass output).
Don't forget that you need active crossover circuitry and a dedicated amplifier (of enough power and good quality). Those devices come in modules to get integrated into the bass box. In this case you should plan to integrate an extra cabinet on the side/back of the box. The cost for a good module will certainly be higher than for a good driver.
Other opinions, anyone?
Good luck 😉
OK, thankyou for all that info. Back to do a bit more research I think - Im now contemplating perhaps an isobaric design since it seems to have a lot going for it, and doesnt look vastly more complex than a sealed box. Of course I need to buy two drivers though !
And I still need to find some specific suitable drivers - I spent today looking at the Peerless 12" XLS but other articles on this forum suggest its not well suited to a sealed box design due to not outputting high enough sound levels in that configuration .... mustnt have a large Xmax Im guessing. So I guess Ill have to pick some other drivers from the manufacturers you mention and see if they are mentoned elsewhere ....
Back to the drawing board for a day or two ...
And I still need to find some specific suitable drivers - I spent today looking at the Peerless 12" XLS but other articles on this forum suggest its not well suited to a sealed box design due to not outputting high enough sound levels in that configuration .... mustnt have a large Xmax Im guessing. So I guess Ill have to pick some other drivers from the manufacturers you mention and see if they are mentoned elsewhere ....
Back to the drawing board for a day or two ...
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