Tweeters, especially this one, do not need a separate enclosure. The D25 has a sealed and damped rear chamber built in.
I like Dave's TMW idea a lot! How does one compensate for baffle step in a single woofer enclosure? [i know there is a thread on this, I will look]
Wouldn't it be much easier to have a single vented box housing both woofers? with one woofer stepped down appropriately.
-andy
I like Dave's TMW idea a lot! How does one compensate for baffle step in a single woofer enclosure? [i know there is a thread on this, I will look]
Your sure? I don't know about that one. The bass alignment should not effect mid response.
Wouldn't it be much easier to have a single vented box housing both woofers? with one woofer stepped down appropriately.
-andy
Re: ok...
3 choices of basic topology. Pluses & minuses anyone?
Note: T is shown above the M, but could as easily be below. Also no internal partitions shown. Andy's idea of loading the drivers differently will have benefits in the midrange. I'd be trying to figure out how to make these work in a TL (or Voigt Pipe).
dave
3 choices of basic topology. Pluses & minuses anyone?
An externally hosted image should be here but it was not working when we last tested it.
Note: T is shown above the M, but could as easily be below. Also no internal partitions shown. Andy's idea of loading the drivers differently will have benefits in the midrange. I'd be trying to figure out how to make these work in a TL (or Voigt Pipe).
dave
I was under the impression that this would be a vented enclosure...that is what Vifa suggests... I have no problem going with a sealed enclosure but I would like to know why we are going ageist manufacture suggestions...
I like the idea of having the woofers back to back like in the first picture...is their any benefit to doing this...and would I have to bind the speakers together? As shown in the diagram?
All these are questions I have and I was originally thought of a vented enclosure...why is this a bad idea?
note: i also like the config in the second pic...straight line...tmm
Thanks,
Slice
I like the idea of having the woofers back to back like in the first picture...is their any benefit to doing this...and would I have to bind the speakers together? As shown in the diagram?
All these are questions I have and I was originally thought of a vented enclosure...why is this a bad idea?
note: i also like the config in the second pic...straight line...tmm
Thanks,
Slice
I am glad to see you are getting somewhere in how your speaks can be constucted. As you go along remember that you are basically going for a theatre(yea, I spelled it right) set up. Something you might keep in mind is that you want to avoid a sweet spot even though these are satellites. A way to avoid that is to use ribbons set sideways. To do that and keep your stereo seperation you can use a metal domed tweeter in the back that will bounce its sound off the wall/corner. The metal dome set at the top of the speaker at a 45 degree angle works great. No sweet spot but still separation.
Get back to work
Thatch
Get back to work
Thatch
manufacturer's recommendations....
are just that. ! They are given (usually) as as optimum average size for driver used in an average single box. They may or may not fit a particular situation.
There are many different alignments for cabinets, you need to choose the one that suits your application best, they have different characteristics. You can read all about this in the "loudspeaker design cookbook"
In the case of the 2.5 tmm, the seal upper driver will give tighter smoother mid and upper bass response at the expense of low bass response and the bass response is being taken care of by the lower woofer in an extended response bass cabinet which will give lower bass than the manufacture's recommended cabinet. By using this method you are getting the most out of the driver combination.
are just that. ! They are given (usually) as as optimum average size for driver used in an average single box. They may or may not fit a particular situation.
There are many different alignments for cabinets, you need to choose the one that suits your application best, they have different characteristics. You can read all about this in the "loudspeaker design cookbook"
In the case of the 2.5 tmm, the seal upper driver will give tighter smoother mid and upper bass response at the expense of low bass response and the bass response is being taken care of by the lower woofer in an extended response bass cabinet which will give lower bass than the manufacture's recommended cabinet. By using this method you are getting the most out of the driver combination.
::You guys are confusing me….Sealed or ported…simple::
So should I or should I not use a ported design?
And I should not use a ported design what should I use…
Some of you guys have suggested sealed?
Could some one upload a picture of the enclosure all of you are suggesting…
I understand pictures better then word…
I am not sure of the design you guys are getting at…
I am sorry that I don’t understand…
In plain words is it going to be sealed or ported that is all I need to know…
Does it have more then one acoustic compartment?
Your words are a little confusing and I am having problems visualizing…
Sealed or ported?
I think you guys are making it sound much more complicated then it really is…
There are three basic enclosure designs… sealed, ported, and band pass…simple…
Witch are we going to be using? Sealed or ported?
So should I or should I not use a ported design?
And I should not use a ported design what should I use…
Some of you guys have suggested sealed?
Could some one upload a picture of the enclosure all of you are suggesting…
I understand pictures better then word…
I am not sure of the design you guys are getting at…
I am sorry that I don’t understand…
In plain words is it going to be sealed or ported that is all I need to know…
Does it have more then one acoustic compartment?
Your words are a little confusing and I am having problems visualizing…
Sealed or ported?
I think you guys are making it sound much more complicated then it really is…
There are three basic enclosure designs… sealed, ported, and band pass…simple…
Witch are we going to be using? Sealed or ported?
Re: ::You guys are confusing me….Sealed or ported…simple::
Both.
The P17 that will be doing bass & midrange should be in a sealed enclosure. This improves its transient response, but more importantly it keeps the excursion down reducing midrange distortion. (this could also be an aperiodic enclosure)
The other P17 won't have to do midrange so we can make it work a little bit harder and tune it to extend the bass as far down as we can, hence the EBS (extended bass shelf) ported enclosure.
With this scheme we also play into the natural tendency of a room to lift the low bass.
The extra brace (aka cabinet partition) doesn't hurt either.
dave
slicemaster101 said:
Both.
The P17 that will be doing bass & midrange should be in a sealed enclosure. This improves its transient response, but more importantly it keeps the excursion down reducing midrange distortion. (this could also be an aperiodic enclosure)
The other P17 won't have to do midrange so we can make it work a little bit harder and tune it to extend the bass as far down as we can, hence the EBS (extended bass shelf) ported enclosure.
With this scheme we also play into the natural tendency of a room to lift the low bass.
The extra brace (aka cabinet partition) doesn't hurt either.
An externally hosted image should be here but it was not working when we last tested it.
dave
Slice, you should be warned, that in a .5 way, phase misalignment within a significant range will be prominent during the attenuation of the .5 speaker, as it blends to reinforce it's counterpart. The main woofer will remain at a relatively constant angle, as the .5 unit's angle shfits and the two signals are no longer coherent for as long as the .5 has any significant output, relative to the reference level of both drivers. This affects the subjective 'clarity' of the speaker system in that range.
I saw another recommendation, to mix a sealed and ported enclosure.....this will also result in phase error, as the phase angle of the sealed woofer will shift 180 degrees from the bass output of the ported woofer output eventually, however these will be even much more noticable than the errors that occur during .5 transition if implemented with like alignments for both woofers. The brain is very sensitive to phase distortions such as this in low frequencies, and the early rolloff of the sealed alignment will cause subjective 'muddiness' over much of the low frequency range that the ported enclosure extends too. Besides, careful ported alignment can yield like results as a sealed in midbass/midrange, as long at tuning is nearly 1 octave or greater below the target frequency you deem to be critical. Near 1 octave or greater, after tuning and signal behaviour is identical to a sealed box. The only problems then, are to eliminate the midrange reflections that will emit from the port, by using a suitable wall lining. Actually, the best results would be yielded if you used the sealed mid enclosure,and ported bass woofer, using a 3 way crossover configuration. This would also significantly reduce IM distortions in the midrange, as well as increase power handling, and you would avoid the nasty phase non linearities that you otherwise have to be content with.
-Chris
I saw another recommendation, to mix a sealed and ported enclosure.....this will also result in phase error, as the phase angle of the sealed woofer will shift 180 degrees from the bass output of the ported woofer output eventually, however these will be even much more noticable than the errors that occur during .5 transition if implemented with like alignments for both woofers. The brain is very sensitive to phase distortions such as this in low frequencies, and the early rolloff of the sealed alignment will cause subjective 'muddiness' over much of the low frequency range that the ported enclosure extends too. Besides, careful ported alignment can yield like results as a sealed in midbass/midrange, as long at tuning is nearly 1 octave or greater below the target frequency you deem to be critical. Near 1 octave or greater, after tuning and signal behaviour is identical to a sealed box. The only problems then, are to eliminate the midrange reflections that will emit from the port, by using a suitable wall lining. Actually, the best results would be yielded if you used the sealed mid enclosure,and ported bass woofer, using a 3 way crossover configuration. This would also significantly reduce IM distortions in the midrange, as well as increase power handling, and you would avoid the nasty phase non linearities that you otherwise have to be content with.
-Chris
Thanks for clarifying
Well that takes care of it…
I shall design a enclosure similar to the revised pictures planet10 has posted….
I will probly go with the design with all drivers on a single baffle…
I would like to design the enclosure itselfe but could you guys help me out with the volumes of the two compartments…as well as port information for the lower compartment…
Thanks,
Slice
Well that takes care of it…
I shall design a enclosure similar to the revised pictures planet10 has posted….
I will probly go with the design with all drivers on a single baffle…
I would like to design the enclosure itselfe but could you guys help me out with the volumes of the two compartments…as well as port information for the lower compartment…
Thanks,
Slice
volumes
BB6 indicates a sealed volume of 4 to 5 litres, (hey, I'm an Aussie , we work metric) for the sealed compartment with about 50% wadding fill (F3=96)
and an extended bass chamber of about 30 litres, tuned to 34Hz with a port of 50mm diam by 125mm long (or 60mm x 185 )
Have fun, will send a possible series x-o if you email me
gradds@iprimus.com.au
Please understand that these are only calculated volumes etc, but BB6 seems to be fairly accurate.
Someone else may wish to put forward a cross-over as well.
Have fun !!!
NP: wendy matthews: witness tree
BB6 indicates a sealed volume of 4 to 5 litres, (hey, I'm an Aussie , we work metric) for the sealed compartment with about 50% wadding fill (F3=96)
and an extended bass chamber of about 30 litres, tuned to 34Hz with a port of 50mm diam by 125mm long (or 60mm x 185 )
Have fun, will send a possible series x-o if you email me
gradds@iprimus.com.au
Please understand that these are only calculated volumes etc, but BB6 seems to be fairly accurate.
Someone else may wish to put forward a cross-over as well.
Have fun !!!
NP: wendy matthews: witness tree
Slice,
Here's an online unit converter. Does everything.
http://www.digitaldutch.com/unitconverter/
HTH
Cheers
Here's an online unit converter. Does everything.
http://www.digitaldutch.com/unitconverter/
HTH
Cheers
CHRIS8 said:
What Chris points out illustrates that there are always compromises to be made when designing a loudspeaker.
The 1st problem is really only an issue in the enclosure with the drivers on the front, in the box with the push-push drivers the output in the problem range of the 2nd (back) driver is in the shadow of the speaker box (any issues with this at all could be eliminated by leaving the 0.5 inductor out and letting the back driver run full-out -- you would have a bi-polar then and would have a differenet set of compromises*).
*(this is actually what i plan to do with 4 of my 16 VIFA P17s -- in a TL inspired ny the TLb)
The 2nd issue won't go away as easily.
Andy -- what sort of Q does that little itty-bitty sealed cabinet give?)
Both of these are directly affected by the width of the cabinet, which is what determines the placement of the 0.5 roll-off. This should be in the region of 4560/cabinet width. I like to push this below 350 Hz which means a cabinet width of 13" or more (with BIG round-overs).
dave
Re: the mesurments seem afuly small...
It is -- that is why i asked the Q question of Andy. I'd tend to give the sealed woofer a bit more breathing room and get the Q quite low, so that it is way down by the time it's phase starts to interact with the vented woofer (as i posted earlier i'd tend to actually load this baby aperiodically).
Note: this is all theory to me. I have never built a system we are describing. Andy has much more practical experience with these drivers.
dave
slicemaster101 said:
It is -- that is why i asked the Q question of Andy. I'd tend to give the sealed woofer a bit more breathing room and get the Q quite low, so that it is way down by the time it's phase starts to interact with the vented woofer (as i posted earlier i'd tend to actually load this baby aperiodically).
Note: this is all theory to me. I have never built a system we are describing. Andy has much more practical experience with these drivers.
dave
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