Black is alwawy in fashion...
I forget the percentage (but 10% sticks in my mind) you can increase your thermal disipation by a good factor just by making your parts black. Obviously thermally concuctive colour like oxide is better than paint but even a black paint job will increase your thermal disipation. So this is almost as easy and free as it gets and it all adds up. Some heat sink expert can supply the fine details. There has also been a fair bit of work done with regards to heat pumping out the pole to an external sink plate. If you are running your pole at saturation then you can afford to stuff some copper into it and scoot it out the back to a plate on the outside of the cabinet. Big massive copper phase plugs or pole extenders will also draw some heat away from the VC. I think that Beyma have published some info on dual coil inside/outside and how much extra heat that can sink away. For a single coil why not simply use a flat wound wire and forget about the former then your coil is free to sink to the pole and the top plate with no thermal insulator in the way, in this situation the former adds no strength so loose it as it is just unwanted extra mass. As always Black is in this year.
I forget the percentage (but 10% sticks in my mind) you can increase your thermal disipation by a good factor just by making your parts black. Obviously thermally concuctive colour like oxide is better than paint but even a black paint job will increase your thermal disipation. So this is almost as easy and free as it gets and it all adds up. Some heat sink expert can supply the fine details. There has also been a fair bit of work done with regards to heat pumping out the pole to an external sink plate. If you are running your pole at saturation then you can afford to stuff some copper into it and scoot it out the back to a plate on the outside of the cabinet. Big massive copper phase plugs or pole extenders will also draw some heat away from the VC. I think that Beyma have published some info on dual coil inside/outside and how much extra heat that can sink away. For a single coil why not simply use a flat wound wire and forget about the former then your coil is free to sink to the pole and the top plate with no thermal insulator in the way, in this situation the former adds no strength so loose it as it is just unwanted extra mass. As always Black is in this year.
Paul W said:
Lynn,
Here are some shots of a BMS 4552ND on a 12" MSC waveguide from about a year ago.
First is a stock WG except that the back side (outside) is covered with a heavy layer of sand and polyester resin.
[/IMG]
Next is the same driver & WG but with a sand texture created by spraying the inside of the WG with enamel and sprinkling dry sand into the wet paint. Virtually no difference, at least in the CSD.
[/IMG]
Request for you... If/when you obtain the 18 Sound ND1460A, would you post a few photos of the phase plug? I've tentatively selected those drivers for a project about 3 months out, but hate to buy them without knowing what the phase plug actually looks like.
Thanks,
Paul
I read somewhere that adding some friction in the throat of horns 'cleans them up" well I tried it with three different horns and in my experiance it's BS. Probably first perpetuated by some sloppy horn manufacture who couldn't get their horn or 'waveguide' smooth in the throat.
The 18 Sound driver you mention above looks like it will be excellent.
Re: Black is alwawy in fashion...
With no former how I am supposed to attach the voice coil to the cone
Our voice coil former is black, our pole is not as we use a chemical treatment that does not come in black last I checked. You can get the phase plugs in black if you desire, they pull the heat from the copper sleeve and pole to the front of the woofer and the moving woofer cone helps to dissipate it into the air outside the cabinet. The Apollo aluminum rings are black anodized should you go that route.
moray james said:
With no former how I am supposed to attach the voice coil to the cone
Our voice coil former is black, our pole is not as we use a chemical treatment that does not come in black last I checked. You can get the phase plugs in black if you desire, they pull the heat from the copper sleeve and pole to the front of the woofer and the moving woofer cone helps to dissipate it into the air outside the cabinet. The Apollo aluminum rings are black anodized should you go that route.
Magnetar said:
Actually I'll go out on the limb here and say I'll bet they sound better than the new Azura horn.
RE 18 Sound XT1464 - I looked closer at this and will now jump off the limb..
To me this has way too narrow of coverage for home hifi rooms. I like my XT120's a lot though.
XT120 - Nice home hifi horn -
The part close to 20K looks different. I think the difference is better viewed via impulse.Paul W said:
Lynn,
Here are some shots of a BMS 4552ND on a 12" MSC waveguide from about a year ago.
First is a stock WG except that the back side (outside) is covered with a heavy layer of sand and polyester resin.
[/IMG]
Next is the same driver & WG but with a sand texture created by spraying the inside of the WG with enamel and sprinkling dry sand into the wet paint. Virtually no difference, at least in the CSD.
[/IMG]
Request for you... If/when you obtain the 18 Sound ND1460A, would you post a few photos of the phase plug? I've tentatively selected those drivers for a project about 3 months out, but hate to buy them without knowing what the phase plug actually looks like.
Thanks,
Paul
Re: Re: Different VC wire
According to the Lowther site above (follow link to technical information):
If they warm up that much with the volume down, what does that say about dynamic compression due to heating when they're actually playing music?
Am I getting old and cynical, or are they trying to sell me some silver-coiled drivers?
John_E_Janowitz said:
According to the Lowther site above (follow link to technical information):
.
If they warm up that much with the volume down, what does that say about dynamic compression due to heating when they're actually playing music?
Am I getting old and cynical, or are they trying to sell me some silver-coiled drivers?
what do you need a former for?
Hey Nick: a stacked up flat wound coil is far more rigid than any former you could use with round wound wire. Western Electric built a beautiful comp driver this way in the late twenties or earlie thirties. They published in the JAES. Cool for a single wind coil but that's it. Good trick though. I think that the conp driver was the 555 but don't quote me.
Hey Nick: a stacked up flat wound coil is far more rigid than any former you could use with round wound wire. Western Electric built a beautiful comp driver this way in the late twenties or earlie thirties. They published in the JAES. Cool for a single wind coil but that's it. Good trick though. I think that the conp driver was the 555 but don't quote me.
nickmckinney said:
No point in beating around the bush - the next purchase decision are the midbass drivers. The ones I'm leaning most strongly towards are a quartet of Altec/GPA 414's with 16-ohm voice coils, a pair of Altec/GPA 416's (with Alnico if available), or a pair of Lambda TD15M's. The Altecs are a known quantity, I've heard them before and like the sound - but I don't know how big a hassle the crossover is going to be.
If the Altecs have any big "secret", I suspect it's basically the underhung voice coil, the particular selection of cone profile, and the famous Altec sticky-damped accordion edge. Excursion, as I see it, is mostly the business of the bass-fill drivers, not the low-Q midbass driver, which is mostly tasked with really good sound in the 200 Hz to 1 kHz region. Between the low Q and high efficiency (97~101 dB), I don't expect to see a lot of cone motion. In this frequency range, magnetic design (including Alnico) and intelligent selection of edge (and spider) damping seem to be the most important factors.
In the range above 1 kHz, I can see the need for exotic cone-termination techniques, since this is where the real clutter starts (frequencies scaled higher in proportion to cone size, of course). That's really a whole different set of constraints, more the domain of typical 6"~8" 2-way systems with 2.5~3.5 kHz crossovers. Been there, done that.
This system isn't about that - it's more a question of the best-sounding drivers to match with a large-format horn/ribbon combination. Big dynamics, but also free of the usual PA grunge in the midrange.
P.S. Nice review by Scholl over in the HE Asylum. He certainly has a way with words - that's one of the most memorable titles I've seen in a while. If I end up buying the TD15M's, I think I would paint the center post semi-matte charcoal gray.
Re: Re: Re: Different VC wire
They mostly perceive some sonic phenomena and they throw in some explanations off the top of their heads IMO. Those things need statistical work and specific data method to become concrete evidence. Drivers can get stiffer if left idle for long. There can be much speculation about a myriad of reasons. I always keep an open mind to subjectivists spotting some phenomena. It is not cool to say some things don't exist just bcs science has other far more serious and obvious priorities to solve. Subjectivists are good hounds for trivia. I just stop listening when they claim they have the explanation and solution too, especially when it is expensive, and readily available.
lousymusician said:
They mostly perceive some sonic phenomena and they throw in some explanations off the top of their heads IMO. Those things need statistical work and specific data method to become concrete evidence. Drivers can get stiffer if left idle for long. There can be much speculation about a myriad of reasons. I always keep an open mind to subjectivists spotting some phenomena. It is not cool to say some things don't exist just bcs science has other far more serious and obvious priorities to solve. Subjectivists are good hounds for trivia. I just stop listening when they claim they have the explanation and solution too, especially when it is expensive, and readily available.
Considering how the LeCleac'h behaves an octave above cutoff, I expect pretty wide dispersion, pretty much the same as the midbass driver.
I don't really expect the XT1464's to be in the same league - for one thing, the AH-425 has the throat specifically designed to match the internal 207 Hz flare rate of the 288 compression driver, while I'd expect the XT1464 to be optimized for the throat profile of the 18Sound drivers. I expect the 288 to mount up to the XT1464 with no trouble, but there's a pretty good chance the flare rates won't match.
Very small mismatches of the flare rates between the compression driver and the entrance to the horn create big reflections. These reflections mess up the time domain, the polar pattern, the frequency response, and, well, the way it sounds. The problems won't be as bad as horns with intentional diffraction "pinches" in the throat, or worse, horns with circular to square-section transitions, but any kind of reflection or diffraction in the throat region is going to cause problems.
I don't really expect the XT1464's to be in the same league - for one thing, the AH-425 has the throat specifically designed to match the internal 207 Hz flare rate of the 288 compression driver, while I'd expect the XT1464 to be optimized for the throat profile of the 18Sound drivers. I expect the 288 to mount up to the XT1464 with no trouble, but there's a pretty good chance the flare rates won't match.
Very small mismatches of the flare rates between the compression driver and the entrance to the horn create big reflections. These reflections mess up the time domain, the polar pattern, the frequency response, and, well, the way it sounds. The problems won't be as bad as horns with intentional diffraction "pinches" in the throat, or worse, horns with circular to square-section transitions, but any kind of reflection or diffraction in the throat region is going to cause problems.
Maybe you can expand the mouth by attaching some makeshift device with foam around the final edges, if the original coverage proves a bit narrow.
I wish you luck with CD to horn throat match. It will make or brake the first attempts.
Why don't you try a couple of Dr. Geddes 15inch waveguides using B&C DE250 ? Polyamide!
Extremely refined pair match. 90 deg all round to boot. Solved worries for rational money and your foam plug for HOM.
I wish you luck with CD to horn throat match. It will make or brake the first attempts.
Why don't you try a couple of Dr. Geddes 15inch waveguides using B&C DE250 ? Polyamide!
Extremely refined pair match. 90 deg all round to boot. Solved worries for rational money and your foam plug for HOM.
Re: what do you need a former for?
We use a flatwire coil where the wire is either square or rectangular. As the coil is being wound there are 2 measuring devices that look at both dimensions all the time (to 0.0001") and adjust the tension as necessary to keep them both in spec (the wire starts off as round stock). This way we can vary both dimensions to get the outer diameter to spec to fit the gap of our motor. This is how we have multiple different 4 layer flatwire aluminum and copper coils with the same outer dimensions as 2 layer roundwire (which we use in lower strength sealed box designs for instance) We also have multiple impedance options for all. In the drivers the H models use 4 layer copper flatwire, the X models use 4 layer aluminum flatwire, the S models use 2 layer roundwire, the M models use 4 layer aluminum flatwire at a shorter winding height than the X model.
You cannot do this with edgewound, and the biggest problem with the edgewound is soldering the lead out wires to the voice coil especially aluminum wire coils. Anyone who has ever tried soldering aluminum knows what I am talking about.
moray james said:
We use a flatwire coil where the wire is either square or rectangular. As the coil is being wound there are 2 measuring devices that look at both dimensions all the time (to 0.0001") and adjust the tension as necessary to keep them both in spec (the wire starts off as round stock). This way we can vary both dimensions to get the outer diameter to spec to fit the gap of our motor. This is how we have multiple different 4 layer flatwire aluminum and copper coils with the same outer dimensions as 2 layer roundwire (which we use in lower strength sealed box designs for instance) We also have multiple impedance options for all. In the drivers the H models use 4 layer copper flatwire, the X models use 4 layer aluminum flatwire, the S models use 2 layer roundwire, the M models use 4 layer aluminum flatwire at a shorter winding height than the X model.
You cannot do this with edgewound, and the biggest problem with the edgewound is soldering the lead out wires to the voice coil especially aluminum wire coils. Anyone who has ever tried soldering aluminum knows what I am talking about.
Lynn Olson said:
The center post (phase plug) you can get in black anodize or raw aluminum if you desire.
I have reconed quite a few Altecs. Its the tiny underhung coil primarily, but also the cone is nice as well. Only thing I don't like is the sharp edge cone termination at the surround for a driver that plays up higher, plus at excursion they can fold over there. We use the same edge damping on the TD15M, we just cover it and the cone at the same time with a lower tack black both for aesthetics and for keeping the cat hairs off.
How about we send you a pair for testing? It won't hurt my feelings if you prefer the Altec's, but I would love your opinions on these.
Time ripe for TD15M Apollo Field Coil?
Great to see you back Nick and Lambda resurrected!
Dunno if you recall the talk on the Lambda list about field coil versions, but if you were ever gonna do that, the time would be now... people have gone FC crazy while you were away.
I reckon some all out TD15M FC Apollos, perhaps with that 755 paper formulation would sell a good few units here. Should have tone, tone tone! I'd certainly grab a pair or 2.
Speaking of those 755, I bet a FC version of that might generate a lot of interest. I know you and John have a lot on your plates at the moment though! Happy to help with modelling stuff in FEMM for these if you like.
Lynn - I haven't heard much of the Altecs but I'm extremely delighted with the (16!) TD15S I bought from Nick way back. I have been running 2 a side pending construction of the dream 8/side dipole stack, with matched high Zout OTLs to get the Q up from 0.22 to 0.6 or so. The latter must wait til I get back to the UK. But don't take my word from it, check this post out from Duke at the asylum.
http://www.audioasylum.com/forums/hug/messages/13/133665.html
Best,
Chris
Great to see you back Nick and Lambda resurrected!
Dunno if you recall the talk on the Lambda list about field coil versions, but if you were ever gonna do that, the time would be now... people have gone FC crazy while you were away.
I reckon some all out TD15M FC Apollos, perhaps with that 755 paper formulation would sell a good few units here. Should have tone, tone tone! I'd certainly grab a pair or 2.
Speaking of those 755, I bet a FC version of that might generate a lot of interest. I know you and John have a lot on your plates at the moment though! Happy to help with modelling stuff in FEMM for these if you like.
Lynn - I haven't heard much of the Altecs but I'm extremely delighted with the (16!) TD15S I bought from Nick way back. I have been running 2 a side pending construction of the dream 8/side dipole stack, with matched high Zout OTLs to get the Q up from 0.22 to 0.6 or so. The latter must wait til I get back to the UK. But don't take my word from it, check this post out from Duke at the asylum.
http://www.audioasylum.com/forums/hug/messages/13/133665.html
Best,
Chris
Re: Re: Different VC wire
Actually CU/Ni is quite common and readily available. Just go to any wire manufacturer. Its used in thermo couples. It only comes round though.
John, this comment about the Lowthars would seem to contradict your opinion that you can put permeable metals in the gap. Comments?
John_E_Janowitz said:
Actually CU/Ni is quite common and readily available. Just go to any wire manufacturer. Its used in thermo couples. It only comes round though.
ABJensen said:
John, this comment about the Lowthars would seem to contradict your opinion that you can put permeable metals in the gap. Comments?
Re: Re: Re: Different VC wire
Anyone who has reconed a bunch of speakers knows the last thing you want near the magnetic gap is anything that can be magnetized. Some people/clubs/sound companies seem to find every piece of metal shaving in the area and dump them into the magnetic gap and wonder why their speakers are buzzing when moving back and forth.
Lowther is also saying to use silver voice coil wires for drivers that get little use? Their voice coils don't have a coating or something? Someone there is making statements that has no clue about how their drivers actually work (and I like Lowthers)
gedlee said:
Anyone who has reconed a bunch of speakers knows the last thing you want near the magnetic gap is anything that can be magnetized. Some people/clubs/sound companies seem to find every piece of metal shaving in the area and dump them into the magnetic gap and wonder why their speakers are buzzing when moving back and forth.
Lowther is also saying to use silver voice coil wires for drivers that get little use? Their voice coils don't have a coating or something? Someone there is making statements that has no clue about how their drivers actually work (and I like Lowthers)