Leeoh,
A 4" driver with bass response? You'll be surprised. Not blow you over bass but very nice.
If you vary the stuffing, it can also help room integration a bit. A room mode may be excited causing a single frequency tone. Changing the placement can help relieve issues with room placement.
Jim
A 4" driver with bass response? You'll be surprised. Not blow you over bass but very nice.
If you vary the stuffing, it can also help room integration a bit. A room mode may be excited causing a single frequency tone. Changing the placement can help relieve issues with room placement.
Jim
yup, it's quite amazing what Mark is able to achieve within both the size and budget of the EL & CHR70s
Jim. Something else has come up - I ordered with the EL70 speakers, port tubes of 50mm internal diameter as specified on your plan. The ones which I received are actually tapered from 55mm ID at the outside end to about 52mm on the end which will be inside the enclosure when I have cut them to length. Should I make some kind of adjustment to length? If so , what would that be? Also, the speaker baffle into which the port tube will be inset is 25mm thick, so how long should the port tubes be if I have to retain these odd sized ones?
Leeoh,
You shouldn't worry too much about the taper of the port tubes. I used tubes that were 52 mm ID in my prototypes so the taper in your tubes shouldn't be a big issue.
Because of the shallow depth of the MLTL chamber (75 mm (3 inches) in my original design), you will have to cut the length of the port tubes to adapt to this length plus the thickness of the baffle. I'm assuming that you do have the ports exiting from the front and rear baffles so you have 75 mm chamber depth plus the thickness of the baffle (25 mm in your case) less a clearance factor so air can exit through the tube. I used 6-7 mm clearance in my prototypes so you should start with tubes about 93 mm long given the thickness of your baffle and the depth of the MLTL chambers. You can shorten the tubes a bit if you need more clearance but the tradeoff is that you slightly raise the low end frequency response if you do.
Jim
You shouldn't worry too much about the taper of the port tubes. I used tubes that were 52 mm ID in my prototypes so the taper in your tubes shouldn't be a big issue.
Because of the shallow depth of the MLTL chamber (75 mm (3 inches) in my original design), you will have to cut the length of the port tubes to adapt to this length plus the thickness of the baffle. I'm assuming that you do have the ports exiting from the front and rear baffles so you have 75 mm chamber depth plus the thickness of the baffle (25 mm in your case) less a clearance factor so air can exit through the tube. I used 6-7 mm clearance in my prototypes so you should start with tubes about 93 mm long given the thickness of your baffle and the depth of the MLTL chambers. You can shorten the tubes a bit if you need more clearance but the tradeoff is that you slightly raise the low end frequency response if you do.
Jim
As I stated in the first post in this thread, I shamelessly used Duke LeJeune's offset bipolar idea in the design of these full range speakers. Duke has recently written a paper on his idea which combines and extends his earlier multipost discussion on another forum. While my design doesn't include a controlled dispersion tweeter like Duke's, you will find the offset bipolar discussion to be interesting. Check out the following:
The Controlled-Pattern Offset Bipole Loudspeaker
http://www.hifizine.com/2010/06/the-controlled-pattern-offset-bipole-loudspeaker/
Jim
The Controlled-Pattern Offset Bipole Loudspeaker
http://www.hifizine.com/2010/06/the-controlled-pattern-offset-bipole-loudspeaker/
Jim
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looks like a great idea....
i have to say i had considered trying this Type of dipole using tapered TL's inverted within a conventional looking rectangular 'box', only with the current drivers im using, and with a 2 way crossover.
I abandoned that idea, due to the added complexity of trying to add another woofer and tweeter to a design, the cost of double the drivers, and mainly as i dont really have the room to space them adequately away from walls.
However, with some nice fullrangers, theres one less reason to stop me trying some.....
Hmm...im thinking now......To the OP: nice design by the way
maybe a 2 way FAST design, featuring a dipole TL mid-tweet section, and a dipole/maybe ripole(?) for the bass section.
i have to say i had considered trying this Type of dipole using tapered TL's inverted within a conventional looking rectangular 'box', only with the current drivers im using, and with a 2 way crossover.
I abandoned that idea, due to the added complexity of trying to add another woofer and tweeter to a design, the cost of double the drivers, and mainly as i dont really have the room to space them adequately away from walls.
However, with some nice fullrangers, theres one less reason to stop me trying some.....
Hmm...im thinking now......To the OP: nice design by the way
maybe a 2 way FAST design, featuring a dipole TL mid-tweet section, and a dipole/maybe ripole(?) for the bass section.
dave at planet 10: i would like to use one of your el70 designs
and make plywood flatpaks. I have paid Martin only a $25 fee.
how to make arrangements for licensing? I have read where a fostex metronome
sounded great with a tube amp but not so hot with a SS amp. Since the qts of the
el70 is about double of the fostex, would you expect a SS amp to work better?
I am trying to make something for tubes. I am not trying to design for low powered
amps though.
thanks for your time. david sundby
and make plywood flatpaks. I have paid Martin only a $25 fee.
how to make arrangements for licensing? I have read where a fostex metronome
sounded great with a tube amp but not so hot with a SS amp. Since the qts of the
el70 is about double of the fostex, would you expect a SS amp to work better?
I am trying to make something for tubes. I am not trying to design for low powered
amps though.
thanks for your time. david sundby
ok typo noted....
di and in Half and Bi as in 2
i thought the meaning was obvious although, maybe it needed clarifying
oh i totally agree. except the bit about sealed and BR....more like BR is less different from aperiodic than it is from sealed, and vice versa for sealed.....I would actually say OB, dipoles, ripoles, bipoles were a little more similar than that.
so a bipolar MLTL, with the drivers such as in the original post, with the drivers displacing in OPPOSITE rather than the same direction, ie mech or elec phase inverted, would constitute a DIPOLE variant wouldn't it dave?
i say this since the 180 phase shift from front wave to back wave would be preserved as in OB, except displaced in the depth dimension, as if a really thick baffle was used...
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BR, sealed, bipole are similar (a bipole is just a regular BR, sealed, box, TL with a 2nd driver, in phase, firing backward (or in looser definitions, up, or too the side)). An OB & a ripole are dipoles and are quite dissimilar from the 1st group.
Bipoles are acoustically in phase. A bipole turned into a dipole by inverting the phase of one driver is at best an intellectual exercise. (even thou some early surrounds were sealed dipoles in an attempt to overcome the shortcomings of very early surround -- they didn't work very well even then)
dave
JIM. i have completed my Offset Bi-polar speakers with the CSS EL:70 speakers and have had them running for about a month. They work very well indeed and I am very pleased with them. I don't have the tech speak, but will just say that there is plenty of good realistic bass and the top is higher and clearer than i would have expected. My only reservation is that the rearward facing speakers don't seem to have any time delay. Maybe it's my aged, mis-treated ears not picking up what they should. They are about two metres from the rear wall but the rear "wall" is actually two floor to ceiling windows, covered with full length curtains. I may get hold of some sheets of chip board and put them over the bottom 5 or so feet of each window. Talking of chipboard, I did the almost unmentionable and used chip board for the entire build. I actually glued two 12mm sheets together
Sorry, the last reply (above) went off prematurely. I retained the original inside dimensions. If it had been necessary to buy ply for the build I would not have done it. Just too expensive. I don't think that anyone should not undertake a build if they can't afford good plywood. I guess that ply would be better than chipboard, (the weight of opinion says so), but chipboard can still give an excellent result. A direct, side by side comparison would probably reveal failings in the chipboard construction but that will never happen with me, so i will just enjoy what i have. And hope that neither Scottmoose or Dave reads this.
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