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#1
Posted to rec.audio.tubes
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Plastic Bobbins
Did you know this about plastic bobbins?
While reading a Jantzen ad I notice that they claimed to "not make coils wound on plastic bobbins due to the risk of microphony." I can only think that perhaps coils in speaker crossovers might be susceptible. Do you think this is a true claim and why? Perhaps Jantzen is gilding the lily? Cordially, west |
#2
Posted to rec.audio.tubes
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Plastic Bobbins
west wrote: Did you know this about plastic bobbins? While reading a Jantzen ad I notice that they claimed to "not make coils wound on plastic bobbins due to the risk of microphony." I can only think that perhaps coils in speaker crossovers might be susceptible. Do you think this is a true claim and why? Perhaps Jantzen is gilding the lily? Please point to the source of that informaton. By your word, it simply is not enough for legitmate comment... or legitimate enough for comment... either way. Peter Wieck Wyncote, PA |
#3
Posted to rec.audio.tubes
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Plastic Bobbins
Peter Wieck wrote: west wrote: Did you know this about plastic bobbins? While reading a Jantzen ad Don't they make swimsuits ? Graham |
#4
Posted to rec.audio.tubes
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Plastic Bobbins
west wrote: Did you know this about plastic bobbins? While reading a Jantzen ad I notice that they claimed to "not make coils wound on plastic bobbins So what do they use ? due to the risk of microphony." I can only think that perhaps coils in speaker crossovers might be susceptible. Why ? Sounds fairly nutty to me for sure. Graham |
#5
Posted to rec.audio.tubes
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Plastic Bobbins
Eeyore wrote: Peter Wieck wrote: west wrote: Did you know this about plastic bobbins? While reading a Jantzen ad Don't they make swimsuits ? Graham Plastic bobbins for crossover coils are notoriously bad items, and often made using plastic that is too thin, and too soft, flimsy, and the result of a corrupt bean counter's mind, and A&R speakers are full of them. Not only that, the winding isn't usually bonded together with varnish or epoxy, and is usually a random wound item and just taped around on completion, and the bobbin is held to a thin masonite board with an Aluminium stud with a steel spring clip which is subject to the magnetic field. But these coils are not very microphonic, certainly not as much as some capacitors were thought to be, such as those un old JBL speakers where they placed the caps in sealed cardboard cylinders, and filled around the cap with CarlyFornia Beach Sand, a very special and rare substance only found on the US west coast in that lesser known seaside village discovered by Karl Ifornia. The village went broke when someone decided polypropylene caps were better and cheaper. The simple test for microphony is to have a signal present and hammer the coils with a mallet, and if any sound is heard via the speaker, then they are microphonic, since wire movement is altering the inductance and slightly amplitude/phase modulating the signal. But chances are the sound of whacking the darn coils at the mallet is louder than any electronic signal is in the speaker, and must lees of an effect than whacking the cables going into a phono preamp, something that proves interconnects can be microphonic, and I am sorry to spoil all audiophile's saturday because now I have given then something else to tear their hair out with worry after spending a zillion bucks on gear.... :-) Happy coil whacking! Meanwhile, watch that goil in de Jantzen, she coulda getta me into a lotta nice trouble... Oh, and I like to wind all my own coils, random is OK, but I like to use varnish so the coil wire is adhered together, and movement is unlikely... Then I use a brass screw and large timber washer to fix the coil to a plywood board for the crossover; no flimsy pcbs are to be found at TA. Patrick Turner. |
#6
Posted to rec.audio.tubes
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Plastic Bobbins
Patrick Turner wrote: Stuff about poor quality-control with coil-winding. And all of it true. True of wood, plastic, epoxy, composite, bakelite, catalin, air and about anything else. Crap made with crap using crap techniques will, usually, result in crap. Inexpensive materials used with great care and proper techniques may give excellent results. Plastic forms sufficiently substantial, carefully made and treated properly will be just fine. And the coils coming off them will be just fine if properly handled and treated thereafter. Stabilzation after winding is absolutely necessary if only to control the inevitable 'settling' effects of the wire, for lack of a better word. But again, there will be some who tell you that putting a NEMA 5-20R 20A @ 125V receptacle into liquid nitrogent for a specified period will result in audible differences from your speakers. Peter Wieck Wyncote, PA |
#7
Posted to rec.audio.tubes
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Plastic Bobbins (source)
"west" wrote in message
news:jJAnh.301$Ul4.156@trnddc05... Did you know this about plastic bobbins? While reading a Jantzen ad I notice that they claimed to "not make coils wound on plastic bobbins due to the risk of microphony." I can only think that perhaps coils in speaker crossovers might be susceptible. Do you think this is a true claim and why? Perhaps Jantzen is gilding the lily? Cordially, west For those who need to know: Jantzen Audio Denmark, www.jantzen-audio.com has the aforementioned ad in "Multi Media Manufacture" a free manufacturer's guide to AV design & development. The ad is in the Jan/Feb 2007, p.9 magazine, highlighting their new "Audio-Z audiophile capacitor line. I'm a bit surprised that they are not recognized. Hope this helps. Cordially, west |
#8
Posted to rec.audio.tubes
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Plastic Bobbins (source)
west wrote: "west" wrote in message Did you know this about plastic bobbins? While reading a Jantzen ad I notice that they claimed to "not make coils wound on plastic bobbins due to the risk of microphony." I can only think that perhaps coils in speaker crossovers might be susceptible. Do you think this is a true claim and why? Perhaps Jantzen is gilding the lily? For those who need to know: Jantzen Audio Denmark, www.jantzen-audio.com has the aforementioned ad in "Multi Media Manufacture" a free manufacturer's guide to AV design & development. The ad is in the Jan/Feb 2007, p.9 magazine, highlighting their new "Audio-Z audiophile capacitor line. I'm a bit surprised that they are not recognized. Hope this helps. Oh a component manufacturer / supplier ! Why didn't you say before ? Graham |
#9
Posted to rec.audio.tubes
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Plastic Bobbins (source)
flipper wrote: Eeyore wrote: west wrote: "west" wrote in message Did you know this about plastic bobbins? While reading a Jantzen ad I notice that they claimed to "not make coils wound on plastic bobbins due to the risk of microphony." I can only think that perhaps coils in speaker crossovers might be susceptible. Do you think this is a true claim and why? Perhaps Jantzen is gilding the lily? For those who need to know: Jantzen Audio Denmark, www.jantzen-audio.com has the aforementioned ad in "Multi Media Manufacture" a free manufacturer's guide to AV design & development. The ad is in the Jan/Feb 2007, p.9 magazine, highlighting their new "Audio-Z audiophile capacitor line. I'm a bit surprised that they are not recognized. Hope this helps. Oh a component manufacturer / supplier ! Why didn't you say before ? He did, quite clearly. No he did not ! Graham |
#10
Posted to rec.audio.tubes
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Plastic Bobbins (source)
"Eeyore" wrote in message ... flipper wrote: Eeyore wrote: west wrote: "west" wrote in message Did you know this about plastic bobbins? While reading a Jantzen ad I notice that they claimed to "not make coils wound on plastic bobbins due to the risk of microphony." I can only think that perhaps coils in speaker crossovers might be susceptible. Do you think this is a true claim and why? Perhaps Jantzen is gilding the lily? For those who need to know: Jantzen Audio Denmark, www.jantzen-audio.com has the aforementioned ad in "Multi Media Manufacture" a free manufacturer's guide to AV design & development. The ad is in the Jan/Feb 2007, p.9 magazine, highlighting their new "Audio-Z audiophile capacitor line. I'm a bit surprised that they are not recognized. Hope this helps. Oh a component manufacturer / supplier ! Why didn't you say before ? He did, quite clearly. No he did not ! Graham "will not make coils on plastic bobbins" means they make coils. Why are you picking fly **** out of pepper instead of keeping the focus on another possible cause for microphonics? BTW: Thanks to Professor Turner for his post which was both informative and cordial. Cordially, west |
#12
Posted to rec.audio.tubes
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Plastic Bobbins (source)
west wrote: "Eeyore" wrote in message ... flipper wrote: Eeyore wrote: west wrote: "west" wrote in message Did you know this about plastic bobbins? While reading a Jantzen ad I notice that they claimed to "not make coils wound on plastic bobbins due to the risk of microphony." I can only think that perhaps coils in speaker crossovers might be susceptible. Do you think this is a true claim and why? Perhaps Jantzen is gilding the lily? For those who need to know: Jantzen Audio Denmark, www.jantzen-audio.com has the aforementioned ad in "Multi Media Manufacture" a free manufacturer's guide to AV design & development. The ad is in the Jan/Feb 2007, p.9 magazine, highlighting their new "Audio-Z audiophile capacitor line. I'm a bit surprised that they are not recognized. Hope this helps. Oh a component manufacturer / supplier ! Why didn't you say before ? He did, quite clearly. No he did not ! Graham "will not make coils on plastic bobbins" means they make coils. Why are you picking fly **** out of pepper instead of keeping the focus on another possible cause for microphonics? BTW: Thanks to Professor Turner for his post which was both informative and cordial. Cordially, west The gear sold by http://www.jantzen-audio.com looks very good. The foil wound coils look very nice for Xovers indeed, and offer excellent performance, but its difficult for the DIYer to build such things because unlike magnet winding wire which is easily available the flat foils is hard to get. No doubt Jantzen prices will horrify the penny pinching diyer. I would think though that neat air cored layer wound round wired coils which are varnished and baked would be quite blameless in sonic/technical performance. To get low winding resistance losses the coils should have not more than 5% of the load value which is in series with a coil, so an inductor of say 4mH in series with say a 6 ohm woofer for a crossover pole at 238 Hz the dcr should be 0.3ohms, and this means using a coil about 2 or 3 times the size of anything usually supplied in generic good brand speakers. Then there are ferrite cores shaped like cotton reels around which less turns of thinner wire may be wound to achieve the low dcr but have the same L, and who knows if these sound better or worse, but when in doubt, don't use iron in X-over coils, just air thankyou very much! Coils used in shunt situations usually don't need to have extremely low dcr, and in fact some effective series R in the form of dcr resistance is quite acceptable in many cases for a damped resonant trap or shunt L of some kind. I make my own bobbins often with plywood cheeks cut from squares of 6mm plywood and drilled to take 25mm timber dowel. The dowl is cut to about 40mm long, and well glued to the cheeks and a 13mm hole drilled through the dowel centre to fit my winding lathe shaft. I try to keep the cross section of the coil square, to ensure an efficient coil so dcr is minimal, and ppl should be prepared to do their own experimenting with wire and inductance meter. Obviously, there is no need to bake the coil on the wooden bobbin; the bobbin usually holds the wire firmly enough, and just soaking with polyurethane furniture varnish is fine and it will eventually dry and cure with air exposure. The completed coil is mounted on the X-over plywood components board and the fixing can be with brass screws through the cheek or another 12mm dowel through the centre of the coil and through the board. Solid, and simple, and not the result of a pea brained bean counter. Engineering Enterprizes in Melbourne, Victoria, sell a range of plastic bobbins but they are all a bit flimsy, although they are a good source for transformer bobbins for E&I laminations. These bobbins can also be used for crossovers and they are stiffer than the round type bobbins. But winding onto rectangular bobbins is a PITA for the uninitiated, and I suggest those who are dedicated and serious and who are equipped tool wize use the wooden bobbin method, or else could use flat PVC sheet and electricians PVC conduit for the centres. Such bulk materials are CHEAP, and very effective. Meanwhile, one can purchase most coils wanted for speakers in the local Jaycar stores in Oz and perhaps WES components, but usually the dcr is dissapointingly high so I never buy any, and if they did have low loss coils avaiable the price would be high and so even though the cost of making hand made specials is higher again who cares, because we end up with something that will last 100 years and work perfectly. Patrick Turner. |
#13
Posted to rec.audio.tubes
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Plastic Bobbins (source)
west wrote: "Eeyore" wrote in message flipper wrote: Eeyore wrote: west wrote: "west" wrote in message Did you know this about plastic bobbins? While reading a Jantzen ad I notice that they claimed to "not make coils wound on plastic bobbins due to the risk of microphony." I can only think that perhaps coils in speaker crossovers might be susceptible. Do you think this is a true claim and why? Perhaps Jantzen is gilding the lily? For those who need to know: Jantzen Audio Denmark, www.jantzen-audio.com has the aforementioned ad in "Multi Media Manufacture" a free manufacturer's guide to AV design & development. The ad is in the Jan/Feb 2007, p.9 magazine, highlighting their new "Audio-Z audiophile capacitor line. I'm a bit surprised that they are not recognized. Hope this helps. Oh a component manufacturer / supplier ! Why didn't you say before ? He did, quite clearly. No he did not ! "will not make coils on plastic bobbins" means they make coils. So ? Many companies make coils including ones I've worked ( consulted ) for. Why are you picking fly **** out of pepper instead of keeping the focus on another possible cause for microphonics? Show me a microphonic inductor and I'll show you Shangi La. Graham |
#14
Posted to rec.audio.tubes
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Plastic Bobbins (source)
flipper wrote: Eeyore wrote: flipper wrote: Eeyore wrote: west wrote: "west" wrote in message Did you know this about plastic bobbins? While reading a Jantzen ad I notice that they claimed to "not make coils wound on plastic bobbins due to the risk of microphony." I can only think that perhaps coils in speaker crossovers might be susceptible. Do you think this is a true claim and why? Perhaps Jantzen is gilding the lily? For those who need to know: Jantzen Audio Denmark, www.jantzen-audio.com has the aforementioned ad in "Multi Media Manufacture" a free manufacturer's guide to AV design & development. The ad is in the Jan/Feb 2007, p.9 magazine, highlighting their new "Audio-Z audiophile capacitor line. I'm a bit surprised that they are not recognized. Hope this helps. Oh a component manufacturer / supplier ! Why didn't you say before ? He did, quite clearly. No he did not ! It's even still up there. "While reading a JANTZEN AD... they claimed to 'NOT MAKE coils wound on..." What's so bloody hard to figure out? In what way does that prove that the Jantzen Co is a component manufacturer ? I have previously *never* come across a *component manufacturer* placing an advertisement in a magazine for the general public. Graham |
#15
Posted to rec.audio.tubes
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Plastic Bobbins (source)
flipper wrote: Eeyore wrote: flipper wrote: Eeyore wrote: flipper wrote: Eeyore wrote: west wrote: "west" wrote in message Did you know this about plastic bobbins? While reading a Jantzen ad I notice that they claimed to "not make coils wound on plastic bobbins due to the risk of microphony." I can only think that perhaps coils in speaker crossovers might be susceptible. Do you think this is a true claim and why? Perhaps Jantzen is gilding the lily? For those who need to know: Jantzen Audio Denmark, www.jantzen-audio.com has the aforementioned ad in "Multi Media Manufacture" a free manufacturer's guide to AV design & development. The ad is in the Jan/Feb 2007, p.9 magazine, highlighting their new "Audio-Z audiophile capacitor line. I'm a bit surprised that they are not recognized. Hope this helps. Oh a component manufacturer / supplier ! Why didn't you say before ? He did, quite clearly. No he did not ! It's even still up there. "While reading a JANTZEN AD... they claimed to 'NOT MAKE coils wound on..." What's so bloody hard to figure out? In what way does that prove that the Jantzen Co is a component manufacturer ? Lordy but you can be a thick headed obstinate arguer for simply the sake of arguing. You see an "ad" and they "make" something. Whether it's a 'proof' or not it's a damn good guess and I'd wager your average Joe with no axe to grind would naturally figure as much. Since when did any advertisement prove the company was purely a coil-winder ? You just felt like poking a stick in his eye and are now trying to find some way to defend poking a stick in his eye. I'll poke a stick in your eye if that's what's required. I have previously *never* come across a *component manufacturer* placing an advertisement in a magazine for the general public. Besides him not originally saying anything about where he saw the ad, 'general public', 'magazine', or whatever, not that it matters one whit 'where' because he saw an AD from someone who MAKES something, you must have a limited reading exposure. Duh ! You are such a waste of space Mr Dolphin. Graham |
#16
Posted to rec.audio.tubes
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Plastic Bobbins (source)
Jon Yaeger wrote: in article kYZnh.664$8B5.578@trnddc08, west at wrote on 1/6/07 10:40 PM: "Eeyore" wrote in message ... flipper wrote: Eeyore wrote: west wrote: "west" wrote in message Did you know this about plastic bobbins? While reading a Jantzen ad I notice that they claimed to "not make coils wound on plastic bobbins due to the risk of microphony." I can only think that perhaps coils in speaker crossovers might be susceptible. Do you think this is a true claim and why? Perhaps Jantzen is gilding the lily? For those who need to know: Jantzen Audio Denmark, www.jantzen-audio.com has the aforementioned ad in "Multi Media Manufacture" a free manufacturer's guide to AV design & development. The ad is in the Jan/Feb 2007, p.9 magazine, highlighting their new "Audio-Z audiophile capacitor line. I'm a bit surprised that they are not recognized. Hope this helps. Oh a component manufacturer / supplier ! Why didn't you say before ? He did, quite clearly. No he did not ! Graham "will not make coils on plastic bobbins" means they make coils. Why are you picking fly **** out of pepper instead of keeping the focus on another possible cause for microphonics? BTW: Thanks to Professor Turner for his post which was both informative and cordial. Cordially, west Definitions of "cordial" on the Web: 1) affable: diffusing warmth and friendliness; "an affable smile"; "an amiable gathering"; "cordial relations"; "a cordial greeting"; "a genial host" 2) showing warm and heartfelt friendliness; "gave us a cordial reception"; "a hearty welcome" Sometimes i also like to drink that red colured codial made with fermented grapes. But never too much, or I can't drive home. I always accept a cordial reception when they hand me a glass of it. Ah, tiz the time of year to drink red cordial to be sure now. And to gaze upon the triodes and listen to some music. Patrick Turner. |
#17
Posted to rec.audio.tubes
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Plastic Bobbins (source)
flipper wrote: On Sun, 07 Jan 2007 13:17:40 +0000, Eeyore wrote: Since when did any advertisement prove the company was purely a coil-winder ? Since when were "component manufacturer" and "purely a coil-winder" synonyms? "west" mentioned neither. Graham |
#18
Posted to rec.audio.tubes
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Plastic Bobbins (source)
Eeyore writes:
Show me a microphonic inductor and I'll show you Shangi La. Graham Don't know about audio, but this is a source of spurs in RF design. You can see them on a spectrum analyzer when your UUT is on a shake table. The coils need to be vacuum impregnated or potted. You can also hear capacitors and inductors in power supplies and amplifiers. I would assume that the properties are somewhat reciprocal. Steve. -- Steven D. Swift, , http://www.novatech-instr.com NOVATECH INSTRUMENTS, INC. P.O. Box 55997 206.301.8986, fax 206.363.4367 Seattle, Washington 98155 USA |
#19
Posted to rec.audio.tubes
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Plastic Bobbins (source)
Steven Swift wrote: Eeyore writes: Show me a microphonic inductor and I'll show you Shangi La. Graham Don't know about audio, but this is a source of spurs in RF design. You can see them on a spectrum analyzer when your UUT is on a shake table. The coils need to be vacuum impregnated or potted. You can also hear capacitors and inductors in power supplies and amplifiers. I would assume that the properties are somewhat reciprocal. On a shaker table you don't surprise me. Graham |
#20
Posted to rec.audio.tubes
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Plastic Bobbins
"Eeyore" wrote in
message west wrote: Did you know this about plastic bobbins? While reading a Jantzen ad I notice that they claimed to "not make coils wound on plastic bobbins So what do they use ? due to the risk of microphony." I can only think that perhaps coils in speaker crossovers might be susceptible. Why ? Sounds fairly nutty to me for sure. Agreed. Note that Pat Turner has to ignore the fact that coils wound on plastic bobbins can be encapsulated in epoxy or dipped in varnish. |
#21
Posted to rec.audio.tubes
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Plastic Bobbins (source)
"Steven Swift" wrote in message
Eeyore writes: Show me a microphonic inductor and I'll show you Shangi La. Graham Don't know about audio, Would you believe that there are some differences between good practice for audio and good practice for RF? but this is a source of spurs in RF design. ....if you ignore accepted practice. You can see them on a spectrum analyzer when your UUT is on a shake table. ....if you ignore accepted practice. The coils need to be vacuum impregnated or potted. Or good practice followed by other means, such as using thicker wire. You can also hear capacitors and inductors in power supplies and amplifiers. You can hear output transistors, as well. Moral of story, don't put them at your sweet spot. That was a real brain teser, wasn't it? ;-) I would assume that the properties are somewhat reciprocal. Logic like that will have you worrying about skin efffect in speaker cables. |
#22
Posted to rec.audio.tubes
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Plastic Bobbins
Arny Krueger wrote: "Eeyore" wrote west wrote: Did you know this about plastic bobbins? While reading a Jantzen ad I notice that they claimed to "not make coils wound on plastic bobbins So what do they use ? due to the risk of microphony." I can only think that perhaps coils in speaker crossovers might be susceptible. Why ? Sounds fairly nutty to me for sure. Agreed. Note that Pat Turner has to ignore the fact that coils wound on plastic bobbins can be encapsulated in epoxy or dipped in varnish. Provided that the former material is non-magnetic it has zero influence on the result. Graham |
#23
Posted to rec.audio.tubes
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Plastic Bobbins
Eeyore wrote: Arny Krueger wrote: "Eeyore" wrote west wrote: Did you know this about plastic bobbins? While reading a Jantzen ad I notice that they claimed to "not make coils wound on plastic bobbins So what do they use ? due to the risk of microphony." I can only think that perhaps coils in speaker crossovers might be susceptible. Why ? Sounds fairly nutty to me for sure. Agreed. Note that Pat Turner has to ignore the fact that coils wound on plastic bobbins can be encapsulated in epoxy or dipped in varnish. Did I have to ignore this? was I forced to ignore it? By whom? Cossover coils can be wound WITHOUT ANY BOBBIN AT ALL. Its probably difficult for the DIYer to achieve because how do you hold the wire in place as you wind it and after you have wound it? Well, that's not impossible and industry has achieved it easily and the diyer can wind the coil in a TEMPORARY bobbin and the wire can be lightly varnished by brushing it on after each layer. Alternatively epoxy can be used to glue the windings as one proceeds. The former bobbin needs to be not likely to adhere to the wires during the wind up so one may have to wax it before winding. When the completed winding is done and the former removed from the lathe and each half removed from each side of the coil the total wound item can be encapuulated in epoxy or whatever to make a solid block with mounting holes for a brass screw. Many boobinless coils are merely held together with 3 or 4 plastic cable-ties after removal of the coil from the lathe where not even a temporary former is used at all and no varnish/glue either. The ties clamp the turns together in a more or less neat nut unlayered bundle, and this is all some makers have done in the crossovers. They use a blob of hot glue to attatch the coil to a PCB. All very slapdash indeed, and the movement of the wires during vibration would cause a change in inductance hence phase or amplitude modulation of any signal present. The loose wound coil done well is not a disaster if it bundled with the ties, or perhaps wound around with string lashings, then dipped in whatever binding substance one wishes to use such as molten wax, polyurtethane varnish, epoxy, etc, as long as such things are not so viscous that they cannot penetrate the coil interior via natural capilliary action. Its not too difficult to make a 'fingered' coil holder for one's winding lathe to allow bundling by cable ties of a wound coil before removal of the coil off the lathe. You just need to be keen, practically minded, and damned determined. But I have often made up my own timber bobbins, and endeavoured to layer wind the coil. Place the bobbin on the lathe, wind the turns, and no more muckinmg around. Neat layering means slightly less turns for a given L. L needs to be measured as the turns go on, and this means removal off the lathe for measurement with an inductance meter connected between the bared start lead of the coil and a small section of bared wire yet to be wound on. This could be very messy without a bobbin. Different wire guages mean different coil dimensions and hence different L and its all too unreliable and difficult to always calculate with Wheeler's Formula or whatever. Best to wind and measure, wind and measure, but with an initial estimate as a guide. And taps are easy. Taps are usually necessary because with diying speakers and the X-overs, the final L, C and R values chosen depend on the very much corrected values of the L,C & R initially chosen by calculation, but which need confirmation my careful accoustic measurements, and in practice the final design of a X-over is very different to the initially calculated design. As a diyer, one expects one's efforts to be better than what can be purchased in the shops, designed bt bean counters and dumbed down by the whole "process". Most speaker X-overs are just calculated, and the results applied without adequate trimming of values to get the simplest LCR arrangement but flattest speaker response that sounds the best, and simplicity means not having to use an absurd number of resonant traps and filters to bring the response that extra 0.5dB closer to best possible, which is NEVER perfectly flat, despite what many makers may say/show in their lie ridden data sheets/graphs. I have tested countless mainstream speakers and have yet to see a single pair ever have a response within +/- 3dB between 50Hz and 15kHz at amy position of the test microphone using pink noise in any room. One does really well to get a speaker to give an *average* response of +/- 2dB across the band, where the average is the average dB of six different mic positions around the listening seat. Many commercially available speakers are utter engineering jokes. No wonder the reviewers give so many different opinions about speakers; the response is very different for every pair they review; all act like de-facto graphic equalizers, and of course, what magazine reviewer has a good bit of testing equipment? Not a huge number of modern made speakers have grossly microphonic coils though. The fashion now due to bean counters selecting the cheapest appraoch of such hidden technology as crossovers is for pre-formed ferrite bobbins, and wire wound on around these tends to remain firmly placed and is thus non microphonic. The cost of iron bobbins must be less than many more turns of what must be bigger diameter wire to achieve the same L and dcr in an air cored coil. Has anyone analysed the effect on thd/imd of iron cored coils used in speaker x-overs? Presumably a spiral core of GOSS, similar to what is used for say a 15VA power tranny could make a nice low dcr coil in series with a bass speaker. So would the thd/imd be worse than any microphonic effects? What is the effect of the iron core non-linearities? Does the use of a solenoid instead of a toroid of GOSS mean that less thd/imd occurs? I can't help but raise more questions, as there are what seem to me to be greater issues involved than the perils of microphonic coils. Provided that the former material is non-magnetic it has zero influence on the result. The dielectric effects would possibly also be negligible at audio F with plastics/wood. Graham Patrick Turner. |
#24
Posted to rec.audio.tubes
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Plastic Bobbins
"Eeyore" wrote in
message Arny Krueger wrote: "Eeyore" wrote west wrote: Did you know this about plastic bobbins? While reading a Jantzen ad I notice that they claimed to "not make coils wound on plastic bobbins So what do they use ? due to the risk of microphony." I can only think that perhaps coils in speaker crossovers might be susceptible. Why ? Sounds fairly nutty to me for sure. Agreed. Note that Pat Turner has to ignore the fact that coils wound on plastic bobbins can be encapsulated in epoxy or dipped in varnish. Provided that the former material is non-magnetic it has zero influence on the result. Well, the former can be mechanically significant. Inductors can be microphonic, but solving that problem is not unmanagably impeded by the use of a plastic former. |
#25
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Plastic Bobbins
"Patrick Turner" wrote in message
Eeyore wrote: Arny Krueger wrote: "Eeyore" wrote west wrote: Did you know this about plastic bobbins? While reading a Jantzen ad I notice that they claimed to "not make coils wound on plastic bobbins So what do they use ? due to the risk of microphony." I can only think that perhaps coils in speaker crossovers might be susceptible. Why ? Sounds fairly nutty to me for sure. Agreed. Note that Pat Turner has to ignore the fact that coils wound on plastic bobbins can be encapsulated in epoxy or dipped in varnish. Did I have to ignore this? was I forced to ignore it? By whom? Nice job of backpedalling, Patrick. Cossover coils can be wound WITHOUT ANY BOBBIN AT ALL. No they can't. Coils in finished products that lack bobbins were wound on temporary bobbins. I guess you've never been in a coil factory, Patrick. Its probably difficult for the DIYer to achieve because how do you hold the wire in place as you wind it and after you have wound it? You use a temporary bobbin, Patrick. I can tell that you never studied machine tool design or industrial engineering and have never been in an electrical or electronics factory. Save your posturing for people that are poorly informed, Patrick. |
#26
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Plastic Bobbins
Arny Krueger wrote: "Patrick Turner" wrote in message Eeyore wrote: Arny Krueger wrote: "Eeyore" wrote west wrote: Did you know this about plastic bobbins? While reading a Jantzen ad I notice that they claimed to "not make coils wound on plastic bobbins So what do they use ? due to the risk of microphony." I can only think that perhaps coils in speaker crossovers might be susceptible. Why ? Sounds fairly nutty to me for sure. Agreed. Note that Pat Turner has to ignore the fact that coils wound on plastic bobbins can be encapsulated in epoxy or dipped in varnish. Did I have to ignore this? was I forced to ignore it? By whom? Nice job of backpedalling, Patrick. Cossover coils can be wound WITHOUT ANY BOBBIN AT ALL. No they can't. Coils in finished products that lack bobbins were wound on temporary bobbins. I guess you've never been in a coil factory, Patrick. Its probably difficult for the DIYer to achieve because how do you hold the wire in place as you wind it and after you have wound it? You use a temporary bobbin, Patrick. I can tell that you never studied machine tool design or industrial engineering and have never been in an electrical or electronics factory. Isn't the 'official' name for such a temporary bobbin a mandrel ? Graham |
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Posted to rec.audio.tubes
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Plastic Bobbins
"Eeyore" wrote in
message Arny Krueger wrote: "Patrick Turner" wrote in message Eeyore wrote: Arny Krueger wrote: "Eeyore" wrote west wrote: Did you know this about plastic bobbins? While reading a Jantzen ad I notice that they claimed to "not make coils wound on plastic bobbins So what do they use ? due to the risk of microphony." I can only think that perhaps coils in speaker crossovers might be susceptible. Why ? Sounds fairly nutty to me for sure. Agreed. Note that Pat Turner has to ignore the fact that coils wound on plastic bobbins can be encapsulated in epoxy or dipped in varnish. Did I have to ignore this? was I forced to ignore it? By whom? Nice job of backpedalling, Patrick. Cossover coils can be wound WITHOUT ANY BOBBIN AT ALL. No they can't. Coils in finished products that lack bobbins were wound on temporary bobbins. I guess you've never been in a coil factory, Patrick. Its probably difficult for the DIYer to achieve because how do you hold the wire in place as you wind it and after you have wound it? You use a temporary bobbin, Patrick. I can tell that you never studied machine tool design or industrial engineering and have never been in an electrical or electronics factory. Isn't the 'official' name for such a temporary bobbin a mandrel ? That is one common kind of temporary bobbin. It's a many-to-many relationship. |
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