Hi,
There is not much to it.
The point of a phaseplug is to sit in the center of the voice-coil and to provide an obstacle for the soundwaves to avoid them producing cancellation (which can reduce the high frequency output and make the sound rough).
So anything about the diameter of the of the polepiece, round and which has a smooth transtition from cylindrical to open will do.
I have used Tubes (the steel pins hold them in place magnetically) and Cigar Tubes and other stuff I cannot remember. Things that where not magnetic I superglued a penny (english, magnetic steel) onto so that the phaseplugs held themselves in place.
Ciao T
There is not much to it.
The point of a phaseplug is to sit in the center of the voice-coil and to provide an obstacle for the soundwaves to avoid them producing cancellation (which can reduce the high frequency output and make the sound rough).
So anything about the diameter of the of the polepiece, round and which has a smooth transtition from cylindrical to open will do.
I have used Tubes (the steel pins hold them in place magnetically) and Cigar Tubes and other stuff I cannot remember. Things that where not magnetic I superglued a penny (english, magnetic steel) onto so that the phaseplugs held themselves in place.
Ciao T
My phase plugs will be coming on monday. Before I abuse/ruin my drivers, can I ask about cutting off the dust cap?
Inside the whizzer cone is the dust cap. It has a raised, stiff rim that I think might be part of the voice coil assembly. Do I cut just inside this ring?
Oh and can someone suggest a good place to buy spikes please?
Inside the whizzer cone is the dust cap. It has a raised, stiff rim that I think might be part of the voice coil assembly. Do I cut just inside this ring?
Oh and can someone suggest a good place to buy spikes please?
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I have metal spikes like the ones recommended above and they work well but realize you will end up putting dents into your cabinets unless you sit them on a coin or something. I think they are best for spiking speakers to the floor thru carpet. I also have these and offer them as a possible alternative when stacking speaker cabinets on top of each other. They are small rubber feet that screw into place rather than just stick on.
Peavey Small Rubber Feet Set of 4 | Parts-Express.com
Using a sharp Xacto knife carefully place the blade INSIDE that rim and slowly spin the driver on a smooth surface. The rim will actually help you maintain a perfect circle. I placed a piece of paper under the magnet allowing a smooth rotation. Apply gentle pressure letting the blade score deeper and deeper until the dustcap cleanly comes off. It will take less than 100 rotations per speaker... you will be done in under 10. Mine came out pretty much perfect. Last night i listened with the 98 cent tweak and decided to remove it because it did not seem to make any audible difference. I have yet to make a phase plug but intend to.
Take it slow. Also, after removing the dustcap there will be little bits of paper here and there. Turn over the driver and gently tap it so any loose debris comes out.
Zilla
Peavey Small Rubber Feet Set of 4 | Parts-Express.com
Using a sharp Xacto knife carefully place the blade INSIDE that rim and slowly spin the driver on a smooth surface. The rim will actually help you maintain a perfect circle. I placed a piece of paper under the magnet allowing a smooth rotation. Apply gentle pressure letting the blade score deeper and deeper until the dustcap cleanly comes off. It will take less than 100 rotations per speaker... you will be done in under 10. Mine came out pretty much perfect. Last night i listened with the 98 cent tweak and decided to remove it because it did not seem to make any audible difference. I have yet to make a phase plug but intend to.
Take it slow. Also, after removing the dustcap there will be little bits of paper here and there. Turn over the driver and gently tap it so any loose debris comes out.
Zilla
FWIW I used a cheap 'lazy susan' until much better ball bearing 'platters' could be had when office chairs began showing up at curbside.
GM
GM
Fun project Godzilla. If one want's to experiment with "Phase Plugs" with out spending large chunks of coin, might I humbly suggest that a pair of model rocket nose cones would suffice?
They come in a number of sizes, and shapes, and the length is easily adjustable as most are made of Balsa wood.
This is a source I found: Model Rocket Nose Cones (Wood)
You can get an idea of the sizes of the cones by checking out the paper tube sizes on the site also.
I've thought of using some of the rocket body tube, and nose cone material to produce a coaxial Beta 12LTA, however the only suitable dome tweeter I was able to locate that would meet the efficiency requirements was an autosound dash mount, and I forget the details on it, I was afraid it would be harsh sounding.
Have fun with your project.
John
They come in a number of sizes, and shapes, and the length is easily adjustable as most are made of Balsa wood.
This is a source I found: Model Rocket Nose Cones (Wood)
You can get an idea of the sizes of the cones by checking out the paper tube sizes on the site also.
I've thought of using some of the rocket body tube, and nose cone material to produce a coaxial Beta 12LTA, however the only suitable dome tweeter I was able to locate that would meet the efficiency requirements was an autosound dash mount, and I forget the details on it, I was afraid it would be harsh sounding.
Have fun with your project.
John
Thanks zilla & GM. I'll give that a go tomorrow. Just watching the Superbowl
Speaking to Mrs JRKO she really likes the Altecs GM posted and has asked if I can incorporate the FT17H into the top unit with the 12LTA. I'm not sure where is best to do this.
What do you guys think - centres level with the LTA or lower/above? Oh and what about inside or outside of the LTA?
I'm gonna add a skirt to the top part to hide spikes and copy the Altec.
Speaking to Mrs JRKO she really likes the Altecs GM posted and has asked if I can incorporate the FT17H into the top unit with the 12LTA. I'm not sure where is best to do this.
What do you guys think - centres level with the LTA or lower/above? Oh and what about inside or outside of the LTA?
I'm gonna add a skirt to the top part to hide spikes and copy the Altec.
You're welcome!
Sure! Conventional wisdom dictates a tweeter be vertically aligned with it centered at the man's ~seated ear height since women's HF hearing is normally superior enough to require a bit of attenuation in comparison; but if listening off axis, then placed somewhere along the 'mid' driver's curve to the outside to help with time delay offset issues can be beneficial, requiring mirror image speakers, though without measuring gear it's tedious to dial in empirically.
Regardless, short of it being in the center of the 'mid' driver, it usually can't be too close to it.
GM
Sure! Conventional wisdom dictates a tweeter be vertically aligned with it centered at the man's ~seated ear height since women's HF hearing is normally superior enough to require a bit of attenuation in comparison; but if listening off axis, then placed somewhere along the 'mid' driver's curve to the outside to help with time delay offset issues can be beneficial, requiring mirror image speakers, though without measuring gear it's tedious to dial in empirically.
Regardless, short of it being in the center of the 'mid' driver, it usually can't be too close to it.
GM
Thanks GM.
In that case I'll mount them on the inside (mirror pair) at about 1630 on an analogue clock face
Just cut my dust cap out (easier that I thought - Thanks for the directions Godzilla & GM) and put in the phase plugs
Think I might paint 'em
In that case I'll mount them on the inside (mirror pair) at about 1630 on an analogue clock face
Just cut my dust cap out (easier that I thought - Thanks for the directions Godzilla & GM) and put in the phase plugs
Think I might paint 'em
Attachments
They are according to Dave's (planet10) dims. 44mm dia 62.5mm long and about 38mm before the transition starts.
I have a second pair that are the same except they are 40mm dia - would you like them gratis?
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Here is the new layout. I've caulked the frames of the 12LTA's, moved the tweeter into their cabinet, added phase plugs and reduced the centre section to just a 1.5 inch baton to look more like the Altecs GM posted. Mrs JRKO tells me they look much better
'zilla, maybe spikes or something? Just paypal me the postage and call it quits
'zilla, maybe spikes or something? Just paypal me the postage and call it quits
Attachments
Funky JRKO,
Do they sound better with the phase plugs? You are almost at a disadvantage here because you've moved so fast with your project (I'm jealous and rationalizing here) that you haven't lived with them long enough for them to really break in, let alone move from the infatuation stage to the "there's that muddy little honk again on acoustic guitar" stage.
I have BetaLTAs running on a pretty well braced pair of open baffles (horrible pic attached) with cheap subs (also Eminence) on the same panel and Aurum Cantus G2 ribbons. I've tried them in a 2ft^3 sealed box; a variably damped BR paired with Altec 806-8As (nice but requires an L-pad on the Altecs); a tall aperiodic box similar to the Hammer Dynamics dimensions (an MLTL that lost momentum because of the outcry from my wife and daughter about the fact that it blocked a couple of windows - who needs light when you've got Sound?) with University compression tweeters; and now the OBs with the subs and the ribbons.
No question that the OB configuration is the best I've heard in my setup (triamped t-amps for the ribbon and the betas, and a QSC pro solid state amp for the subs, EQ'd by a Behringer DEQX2496 and crossed actively with a DCX2496 crossover). Pretty everything sounds good, and acoustic bass sounds wonderful.
I'm crossing the Betas pretty low to the ribbon (6.5kHz) because of beaming and honking and the ragged response of the Beta above about 5kHz, but I am wondering if dustcap removal and phase plugs would help the Betas keep it smoother into the 9kHz or so range. The Aurum Cantuses sound fine at 6kHz, ragged coming in much lower, and still sweeter coming in higher. But the Betas don't sound so good to me crossed any higher than 6.5kHz.
From what Godzilla is saying, it sounds like dust cap and phase plug (and a little Damar?) might take it just that little bit farther.
Listening to this setup with almost any type of program material, the thing that keeps hitting me is - air! As in pressure. The bigger driver really does seem to make a difference in the physical impact of the sound.
Many thanks to JRKO, Godzilla, ThorstenL, planet10, GM, and all the others who have contributed to the deepest discussion I've yet seen (aside from the original Afterburner project page) of this very versatile driver.
http://thansaffel.com/sites/default/files/imagecache/lightbox/ts_beta12ltas_ob_jan2011.jpg
Do they sound better with the phase plugs? You are almost at a disadvantage here because you've moved so fast with your project (I'm jealous and rationalizing here) that you haven't lived with them long enough for them to really break in, let alone move from the infatuation stage to the "there's that muddy little honk again on acoustic guitar" stage.
I have BetaLTAs running on a pretty well braced pair of open baffles (horrible pic attached) with cheap subs (also Eminence) on the same panel and Aurum Cantus G2 ribbons. I've tried them in a 2ft^3 sealed box; a variably damped BR paired with Altec 806-8As (nice but requires an L-pad on the Altecs); a tall aperiodic box similar to the Hammer Dynamics dimensions (an MLTL that lost momentum because of the outcry from my wife and daughter about the fact that it blocked a couple of windows - who needs light when you've got Sound?) with University compression tweeters; and now the OBs with the subs and the ribbons.
No question that the OB configuration is the best I've heard in my setup (triamped t-amps for the ribbon and the betas, and a QSC pro solid state amp for the subs, EQ'd by a Behringer DEQX2496 and crossed actively with a DCX2496 crossover). Pretty everything sounds good, and acoustic bass sounds wonderful.
I'm crossing the Betas pretty low to the ribbon (6.5kHz) because of beaming and honking and the ragged response of the Beta above about 5kHz, but I am wondering if dustcap removal and phase plugs would help the Betas keep it smoother into the 9kHz or so range. The Aurum Cantuses sound fine at 6kHz, ragged coming in much lower, and still sweeter coming in higher. But the Betas don't sound so good to me crossed any higher than 6.5kHz.
From what Godzilla is saying, it sounds like dust cap and phase plug (and a little Damar?) might take it just that little bit farther.
Listening to this setup with almost any type of program material, the thing that keeps hitting me is - air! As in pressure. The bigger driver really does seem to make a difference in the physical impact of the sound.
Many thanks to JRKO, Godzilla, ThorstenL, planet10, GM, and all the others who have contributed to the deepest discussion I've yet seen (aside from the original Afterburner project page) of this very versatile driver.
http://thansaffel.com/sites/default/files/imagecache/lightbox/ts_beta12ltas_ob_jan2011.jpg
>>> Do they sound better with the phase plugs? You are almost at a disadvantage here because you've moved so fast with your project (I'm jealous and rationalizing here) that you haven't lived with them long enough for them to really break in…
Great question! I lived with the Beta’s for a few weeks before cutting off the dustcaps. They sound better cut off. I cut them off because their sound was too resonant and probably would have caused me to move to another driver altogether if the sound did not improve. Having played with different sized lightbulbs in the center I can hear the sound will indeed smooth further with a phase plug so I believe it will be a worthwhile addition. The charts provided by db earlier in this thread offer a visualization of what happens when you cut the dustcap off, add a phase plug and eventually cut the whizzer off altogether. They are useful charts indeed! You can see the large peak centered at 6.5k reduced after dustcap removal and reduce further with the addition of phase plug. In fact the response looks pretty smooth after those tweaks are done.
The reason you have played with the Beta 12lta so much is because they have an inherent goodness about them. They offer satisfyingly vivid sound you just don’t get with smaller full range drivers (that I’ve heard anyway). They do respond well to super tweeters of different types and work in sealed, ported, back horn and open baffle cabinets. One day I may build open baffles for them just like you have but for now enjoy them in sealed with helper woofers.
I believe you will enjoy them more without the dustcaps. The change is not drastic, just better. I have not tried dammar tho... i doubt i will at this point but it might smooth things out even more if applied to just the whizzer. I also think there is more going on here than just frequency response. They move air and bristle to life even when juiced lightly (t-amps or tubes) and offer insight into the music less efficient drivers don't. I think the larger diameter offers 'more' sound than smaller drivers and it's not monopolized by just the 12lta.
I can't wait to go home tonight and listen to music... but the 12lta is not the only reason, large open baffle woofers also contribute to the overall satisfaction... and the performers like Shelby Lynne, Eva Cassidy and Simon & Garfunkel simply relax and move me these days.
Great question! I lived with the Beta’s for a few weeks before cutting off the dustcaps. They sound better cut off. I cut them off because their sound was too resonant and probably would have caused me to move to another driver altogether if the sound did not improve. Having played with different sized lightbulbs in the center I can hear the sound will indeed smooth further with a phase plug so I believe it will be a worthwhile addition. The charts provided by db earlier in this thread offer a visualization of what happens when you cut the dustcap off, add a phase plug and eventually cut the whizzer off altogether. They are useful charts indeed! You can see the large peak centered at 6.5k reduced after dustcap removal and reduce further with the addition of phase plug. In fact the response looks pretty smooth after those tweaks are done.
The reason you have played with the Beta 12lta so much is because they have an inherent goodness about them. They offer satisfyingly vivid sound you just don’t get with smaller full range drivers (that I’ve heard anyway). They do respond well to super tweeters of different types and work in sealed, ported, back horn and open baffle cabinets. One day I may build open baffles for them just like you have but for now enjoy them in sealed with helper woofers.
I believe you will enjoy them more without the dustcaps. The change is not drastic, just better. I have not tried dammar tho... i doubt i will at this point but it might smooth things out even more if applied to just the whizzer. I also think there is more going on here than just frequency response. They move air and bristle to life even when juiced lightly (t-amps or tubes) and offer insight into the music less efficient drivers don't. I think the larger diameter offers 'more' sound than smaller drivers and it's not monopolized by just the 12lta.
I can't wait to go home tonight and listen to music... but the 12lta is not the only reason, large open baffle woofers also contribute to the overall satisfaction... and the performers like Shelby Lynne, Eva Cassidy and Simon & Garfunkel simply relax and move me these days.
Godzilla,
I did check out the frequency plots but I am a little skeptical of freq plots due to my own difficulties using them as an EQing tool. It is a black art, because I am a graphic designer, not a scientist. I guess if I were a scientist, it would be a science, and design a black art.
THREAD HIJACK ALERT: Zilla, I happened upon your Tang Band W8-1808 project almost at the same time this thread got going, because that looks like a very promising driver as well. Do you think the W8-1808s offer a similar sense of space and pulse as the Betas, with more refinement? Or are we moving more toward a studio monitor as opposed to a pro sound "live" feel there?
Noew here's the "hijack" part: GM, Zilla, anyone - Do you think my 16-ohm Altec 416As are a viable candidate as an H-frame sub to complement either of these drivers? I don't really want something huge (like an Onken) to put those woofers in. OB in general, and H-frame subs in particular, are really exciting to me because they suggest the possibility of somewhat reasonably sized boxes.
I am coming to this approach after a couple of years of taking over my family's living space with JE Labs open baffles, Valencia clone BR boxes, and 816A bass bins topped by Altec 291-16As.
Whatever I do with those, they have to get to GPA first for some surround repairs and T-S parameter testing. But it's good to have way too many projects on deck, right?
I did check out the frequency plots but I am a little skeptical of freq plots due to my own difficulties using them as an EQing tool. It is a black art, because I am a graphic designer, not a scientist. I guess if I were a scientist, it would be a science, and design a black art.
THREAD HIJACK ALERT: Zilla, I happened upon your Tang Band W8-1808 project almost at the same time this thread got going, because that looks like a very promising driver as well. Do you think the W8-1808s offer a similar sense of space and pulse as the Betas, with more refinement? Or are we moving more toward a studio monitor as opposed to a pro sound "live" feel there?
Noew here's the "hijack" part: GM, Zilla, anyone - Do you think my 16-ohm Altec 416As are a viable candidate as an H-frame sub to complement either of these drivers? I don't really want something huge (like an Onken) to put those woofers in. OB in general, and H-frame subs in particular, are really exciting to me because they suggest the possibility of somewhat reasonably sized boxes.
I am coming to this approach after a couple of years of taking over my family's living space with JE Labs open baffles, Valencia clone BR boxes, and 816A bass bins topped by Altec 291-16As.
Whatever I do with those, they have to get to GPA first for some surround repairs and T-S parameter testing. But it's good to have way too many projects on deck, right?
They certainly do sound better with the phase plugs, WAY smoother and far les directional I think.
They were running in rough cabinets for nearly a month, 24hrs a day for the 1st week so definitely run in. I was getting so used to the sound adding a tweeter was a revalation adding high freq. information.
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