I'm liking the sound of this front and rear MTM thing now. But I wonder why I've never seen it done before.
Looking at the standing waves for that enclosure: http://www.vikash.info/audio/standing_wave_calc/?submit_action=calc&height=480&width=190&depth=328.5&threshold=50 you can see which SW's are close to each other.
This raises the question of how far apart SW frequencies ought to be, to which I don't have an answer. I've used 50Hz as default, so it shows all standing waves within 50Hz of each other. You can change this threshold.
This raises the question of how far apart SW frequencies ought to be, to which I don't have an answer. I've used 50Hz as default, so it shows all standing waves within 50Hz of each other. You can change this threshold.
I prefer the idea first mentioned by Sreten. 1 driver as mid, and two for bass. The bass upper end rolls off at the calculated BS point to fully compensate for the BS. I'll have both my drivers at the front, and it makes speaker placement easier too.
The standing wave calculation for the winisd optimum calculation is
http://www.vikash.info/audio/standi...ight=325.6&width=499.9&depth=210&threshold=50
Are we able to tell which is the prefered enclosure to use.
i have yet to calculate any internal bracing, damping or port volumes which i need to add to the overall volume figure generated by winisd so do not take my values as the finished article if anyone was considering my dimensions 😉
am i missing something vikash but does two bass and 1 mid equal three??? or does one driver do bass and mid??
excuse alll the questions it's light relief from from my final project submission............
m
http://www.vikash.info/audio/standi...ight=325.6&width=499.9&depth=210&threshold=50
Are we able to tell which is the prefered enclosure to use.
i have yet to calculate any internal bracing, damping or port volumes which i need to add to the overall volume figure generated by winisd so do not take my values as the finished article if anyone was considering my dimensions 😉
am i missing something vikash but does two bass and 1 mid equal three??? or does one driver do bass and mid??
excuse alll the questions it's light relief from from my final project submission............
m
D1GGY and SimontY,
You say you've never seen the front/rear mounting scheme before? I bet you have. The dreaded B-word... Bose.
Whilst it seems good in principle, I'm not convinced by this method, as by driving the rear driver full-range (to all intents and purposes) you get a lot of reflected sound. Some like this sound, I don't. Worth a try if you're curious I suppose.
Going back to my earlier post detailing the time-alignment. You could build a TMM configuration (thereby implementing 2.5-way) and use normal-polarity tweeter connection as this tilts in the opposite way. But this then has the disadvantage of worse group delay.
You say you've never seen the front/rear mounting scheme before? I bet you have. The dreaded B-word... Bose.
Whilst it seems good in principle, I'm not convinced by this method, as by driving the rear driver full-range (to all intents and purposes) you get a lot of reflected sound. Some like this sound, I don't. Worth a try if you're curious I suppose.
Going back to my earlier post detailing the time-alignment. You could build a TMM configuration (thereby implementing 2.5-way) and use normal-polarity tweeter connection as this tilts in the opposite way. But this then has the disadvantage of worse group delay.
I suppose I have not any experience with the rear mounted woofer so i cant comment on its subjective quality. This is one reason why I am going to give it a bash, see how good the results are.
Dipoles to me sound very good inc the rear wave so who knows. Personal taste obviously comes into this significantly. From a money point of view driver on the back makes sense, less components required in the xover for either BSC in an MTM or the filter for the second driver in a 2.5 way.
But this is only another way to get around baffle step, none of them are clearly superior so it is a a matter of taste. If I had six drivers and was building a floorstander then I would also go with a three way.
Vikash if you using a 15cm width baffle you are going to want to crossover no higher then about 300hz. Preferably a little lower, say 200. 200 works better with respect to compensating for baffle step with the highpass on the midrange driver.
Dipoles to me sound very good inc the rear wave so who knows. Personal taste obviously comes into this significantly. From a money point of view driver on the back makes sense, less components required in the xover for either BSC in an MTM or the filter for the second driver in a 2.5 way.
But this is only another way to get around baffle step, none of them are clearly superior so it is a a matter of taste. If I had six drivers and was building a floorstander then I would also go with a three way.
Vikash if you using a 15cm width baffle you are going to want to crossover no higher then about 300hz. Preferably a little lower, say 200. 200 works better with respect to compensating for baffle step with the highpass on the midrange driver.
Seeing you all seem to be geting into the rear mounted 0.5
way thing perhaps there's a few things I could mention :
1) a full bipole with two tweeters is an option,
bipoles don't have BS, so c/o design is simpler.
2) Back to back mounting of the drivers with force cancellation
by linking the magnets and decoupled mounting is an option.
3) With back to back mounting it seems dipolar treble best matches
bipolar bass/mids mounting, makes sense it terms of off axis response,
and allows the front tweeter to be aligned with the front bass mid in
phase, presumably the extra phase shift with the out phase rear
tweeter matches the extra offset introduced by the mounting.
http://www.t-linespeakers.org/projects/tlB/intro.html
There's no reason why the same cannot be applied to
sealed or reflex speakers, it does have some appeal,
especially the force cancellation aspects, and TBH IMO
it seems one way of getting past the "normal" way of
building a speaker and has quite a few advantages.
🙂 sreten.
way thing perhaps there's a few things I could mention :
1) a full bipole with two tweeters is an option,
bipoles don't have BS, so c/o design is simpler.
2) Back to back mounting of the drivers with force cancellation
by linking the magnets and decoupled mounting is an option.
3) With back to back mounting it seems dipolar treble best matches
bipolar bass/mids mounting, makes sense it terms of off axis response,
and allows the front tweeter to be aligned with the front bass mid in
phase, presumably the extra phase shift with the out phase rear
tweeter matches the extra offset introduced by the mounting.
http://www.t-linespeakers.org/projects/tlB/intro.html
There's no reason why the same cannot be applied to
sealed or reflex speakers, it does have some appeal,
especially the force cancellation aspects, and TBH IMO
it seems one way of getting past the "normal" way of
building a speaker and has quite a few advantages.
🙂 sreten.
I like the idea of 2 bass 1 mid and 1 tweet. I wondered about a BMT on the front baffle and one B on the rear. I have SoundEasy, but I'm not sure if you can model that (My limited knowledge of SE certainly doesn't allow it! 🙂 )
I did find a nice Audax tweeter at Maplins...Part LA13P (TM025M0). It is a 55W which is fairly flat priced at £14.99 in my catalogue. A more expensive one is the TW034X0 (MY22Y) priced at £24.99.
The TM025M0 shocked me by its sheer (physical) weight which I wasn't expecting compared to theTM025F1 (UZ00A - £11.99). The sound is much easier going after two hours listening than the F1.
The TW034X0 seems to exhibit a rise in freq response from 7kHz extending beyond 20kHz. Along with the 93dB, you may find this far too bright at the top end, unless it is moved slightly off axis, or compensated for in the xover.
Gaz
I did find a nice Audax tweeter at Maplins...Part LA13P (TM025M0). It is a 55W which is fairly flat priced at £14.99 in my catalogue. A more expensive one is the TW034X0 (MY22Y) priced at £24.99.
The TM025M0 shocked me by its sheer (physical) weight which I wasn't expecting compared to theTM025F1 (UZ00A - £11.99). The sound is much easier going after two hours listening than the F1.
The TW034X0 seems to exhibit a rise in freq response from 7kHz extending beyond 20kHz. Along with the 93dB, you may find this far too bright at the top end, unless it is moved slightly off axis, or compensated for in the xover.
Gaz
Hi gaz,Rarkov said:
The TW034X0 doesn't necessarily need compensation, it sounds great as it comes. Nicely free of harshness.
It's been discussed here as it's on offer for £15 iirc. It too will shock you with it's sheer physical size... and weight!!
Strictly speaking, the results I posted in post #324 appear better. But it should be clear that I wrote the calc as a theory learning exercise, and don't really know how much real world difference there is between those two examples (for example). Don't forget that with bracing, stuffing etc. the standing waves change - are attenuated and/or further spread out. By all means, use the 'optimum' as a base and adjust the dimensions to meet your aesthetic requirements, and then use the calc to make sure there isn't too much difference in SW's. That's how I would do it.D1GGY said:
About the calc:
Basically you want the minimum total number of matching freqs (highlighted red) and it's better to have them at higher orders if they are (the higher the order, the more attenuated the standing wave). This should enable you to start assessing one enclosure from another.
yes. I'm planning three AP100Z0's and 1 tweeter per enclosure. The two that do bass should start at the baffle step frequency thus providing the extra output to compensate for it. The mid will still output the same level as both bass units in theory.D1GGY said:
I haven't got round to doing any baffle step calculations, but for some reason I was under the impressions that the bass units would need to go up to 700+Hz. Why does the 200 work better with respect to compensating for BS (than 300)? Crossover design and BSC is new to me, so bear with me5th element said:
Apologies for jumping in on this thread and for my complete n00bness....but here goes.
The more I read, the more I get confused so I've decided to just blurt out what I've got running through my head to see if I'm on the right
track. 🙂
The biggest design issue I have is with the footprint of the speakers since I intend to use them as part of my computer/CD setup and they will
be placed on either side of the monitor (which is in the corner of the room). Ideally I want a footprint of 180mmx180mm or less where
internal volume can be made up from height (up to 700mm max) to accomadate bass tuning. I imagine I'll build a sub at a later stage to go
with these to help out the bass depatment where needed.
I currently have a Yaqin integrated valve amp 50w+50w (6ohm).
As I'm building on a budget the Audax AP100Z0 would suit my price needs nicely however I'm concerened about the power handling and sensitivity
of the drivers.
I was once told that it's best to use high sensitivity speakers (>90db) for valve amps and so that's what I want to design/build.
With that in mind I have been thinking along the lines of running drivers in parallel/series in order to increase the power handling and
sensitivity.
The first idea I have is a 2.5way system design where the midbass drivers and 0.5 woof are doubled up to increase power capabilities.
The second idea is a 3way system setup, again with mid/bass drivers doubled up to increase power handling.
The biggest concern I have is with the crossover design as with my limited knowledge and minimal results obtained from searching I still can't
figure out what kind of impedance, SPL and power handling I'll get with doubling up the speakers.
So to recap (becuase I'm a babbling idiot and probably messed up somewhere)...I want to design/build
6-8ohm speakers (ideally 6ohm to match the amp but it'll run 8ohm fine)
high sensitivity (>90db)
able to handle 50w
smallish footprint.
Am I even close to a sound idea or am I completely barking mad?
Thanks for any help.
The more I read, the more I get confused so I've decided to just blurt out what I've got running through my head to see if I'm on the right
track. 🙂
The biggest design issue I have is with the footprint of the speakers since I intend to use them as part of my computer/CD setup and they will
be placed on either side of the monitor (which is in the corner of the room). Ideally I want a footprint of 180mmx180mm or less where
internal volume can be made up from height (up to 700mm max) to accomadate bass tuning. I imagine I'll build a sub at a later stage to go
with these to help out the bass depatment where needed.
I currently have a Yaqin integrated valve amp 50w+50w (6ohm).
As I'm building on a budget the Audax AP100Z0 would suit my price needs nicely however I'm concerened about the power handling and sensitivity
of the drivers.
I was once told that it's best to use high sensitivity speakers (>90db) for valve amps and so that's what I want to design/build.
With that in mind I have been thinking along the lines of running drivers in parallel/series in order to increase the power handling and
sensitivity.
The first idea I have is a 2.5way system design where the midbass drivers and 0.5 woof are doubled up to increase power capabilities.
An externally hosted image should be here but it was not working when we last tested it.
The second idea is a 3way system setup, again with mid/bass drivers doubled up to increase power handling.
An externally hosted image should be here but it was not working when we last tested it.
The biggest concern I have is with the crossover design as with my limited knowledge and minimal results obtained from searching I still can't
figure out what kind of impedance, SPL and power handling I'll get with doubling up the speakers.
So to recap (becuase I'm a babbling idiot and probably messed up somewhere)...I want to design/build
6-8ohm speakers (ideally 6ohm to match the amp but it'll run 8ohm fine)
high sensitivity (>90db)
able to handle 50w
smallish footprint.
Am I even close to a sound idea or am I completely barking mad?
Thanks for any help.
Welcome to diyAudio!
All your specs seem OK, however, don't get caught up in the high sensetivity issue. That is a problem for SET valve amps and the like that put out 8W Max or less. 50W is going to have no problems and is more powerful than most entry level SS amps!
Off topic: What is the CAD software you're using? Seems quite cool... And where is the UK are you?
Gaz
All your specs seem OK, however, don't get caught up in the high sensetivity issue. That is a problem for SET valve amps and the like that put out 8W Max or less. 50W is going to have no problems and is more powerful than most entry level SS amps!
Off topic: What is the CAD software you're using? Seems quite cool... And where is the UK are you?
Gaz
Rarkov said:
I thought that a greater sensitivity gave more sound per watt though (which I like the sound of) and I like my music loud at times so would be a feature I'd want.
Rarkov said:
That's not CAD...just a quick 3D Studio Max wireframe knock-up and a lil photoshop labelling on top.
Anything more than a couple of watts will push these drivers beyond their excursion limits in the bass department anyway. 8 Watts of clean power would probably suffice, and 50 watts...well I don't think you need to worry about having enough power 😉nubbins said:
Yep, if you want to play loud you'll need at least 4 on bass duties I reckon, but more would be ideal. Such a small cone will have to move a long way to push a lot of air, and they can't move very far, so the only thing you can do is add more of them! 4 of these are probably roughly equal to one single 8" driver, though I've not looked at the figures...Vikash said:
I would go with your first suggestion:
"...a 2.5way system design where the midbass drivers and 0.5 woof are doubled up to increase power capabilities."
If you kept your mid/bass drivers in sealed enclosures and the bass only/'0.5' drivers ported the overall cabinet could be reasonably compact, as you desire.
You just need to design a simple 2-way x-over for the tweeter and mid-basses, then tack on an extra inductor (something like 2mH) in series with the '0.5' bass drivers. You'll want to use an iron-cored inductor, to keep the resistance as low as possible, or you may lose a lot of bass definition.
This sound like what you want?
I think if you want kick-*** bass you're looking at 6 or 7 drivers per speaker, as a minumum, but 4 would be cool. 😎
Given the less than stellar bass extension of the driver (Fs ~ 80Hz)
I'd suggest 4 used as bass drivers would be a sensible maximum.
Note that maximum bass SPL of 4 drivers is 12dB more than one.
(3 drivers 9.5 dB, 2 drivers 6dB, 5 = 14dB, 6 = 15.5dB, 7 = 17dB)
🙂 sreten.
I'd suggest 4 used as bass drivers would be a sensible maximum.
Note that maximum bass SPL of 4 drivers is 12dB more than one.
(3 drivers 9.5 dB, 2 drivers 6dB, 5 = 14dB, 6 = 15.5dB, 7 = 17dB)
🙂 sreten.
Please learn us why Mr. Stret., I don't understand! 😕sreten said:
Is that because adding more would be improving one aspect far above other worse ones (high FS), and it would be better just using better drivers???
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