30watt fieldcoil it's equal to a motor structure that move 1watt speaker with ligh papercone?
Physics laws are to simply in this case...
Because you suppose that the fieldcoil current is costant during the speakers use...
I don't think so...
Or you have a modu costant current psu?
Impossible...
if 1 watt was applied at voice coil, i think 0.8watt (air gap) or less, reduce the field coil current...
0.8/30w it's equal to 2,6% of distortion...
Whit only 1 watt applied to the voice coil... Wow...
Physics laws are to simply in this case...
Because you suppose that the fieldcoil current is costant during the speakers use...
I don't think so...
Or you have a modu costant current psu?
Impossible...
if 1 watt was applied at voice coil, i think 0.8watt (air gap) or less, reduce the field coil current...
0.8/30w it's equal to 2,6% of distortion...
Whit only 1 watt applied to the voice coil... Wow...
I think the idea is to saturate the steel, so the field coil doesn't act like a large secondary winding coupled to the voicecoil. At that point it would be the leakage coupling the two coils, which may still matter, who knows. A constant current power source for the field coil would probably be best. But then how many volts EMF would you get from the field coil while the voicecoil is driven, what is the turns ratio? Could it be dangerously large?
Has anyone tried powering the voicecoil without the field coil on, and just measuring the field coil voltage in response to it? Also has anyone measured voicecoil impedance while the field coil is shorted and open?
Has anyone tried powering the voicecoil without the field coil on, and just measuring the field coil voltage in response to it? Also has anyone measured voicecoil impedance while the field coil is shorted and open?
You are in the wrong hobby if you are worried the power consumption of a field coil driver. The theory is well understood. Why? Because we can and want.
Go make some noise in a cable thread or outside a sports car dealer somewhere, and get the same result. No one cares about your opinion.
Sent from my GT-I8200 using Tapatalk
zedda, I understand it is a big thread but try and go through it. You will find most of your answers.
Hi keantoken, i dont see how the result would be useful. You can just calculate it if you want. I think we cannot eliminate the DC magnetic field because this has a big impact on the permeability of the magnetic circuit, dropping as the flux density increases.
Your experiment can be easily conducted in FEMM however, and if you desire i will post a script for that if you find it useful in any way.
Hi keantoken, i dont see how the result would be useful. You can just calculate it if you want. I think we cannot eliminate the DC magnetic field because this has a big impact on the permeability of the magnetic circuit, dropping as the flux density increases.
Your experiment can be easily conducted in FEMM however, and if you desire i will post a script for that if you find it useful in any way.
Dear Zedda,
I dont' know , have you heard music from field coil speaker ever ? or Do you have a field coil speaker system ?
If you heard from the kind of speaker or you might have, I think that you did not tell that way.
Simply thinking about operation of the speaker depending on magnet field to be created from electric motor.
We can hear anything (music) from the speaker without magnet ? I am sure that voice coil will be damaged soon when supplying power for it. So we need to measure anything ?
It is only speaker, FC speaker at all !
Thanks.
I dont' know , have you heard music from field coil speaker ever ? or Do you have a field coil speaker system ?
If you heard from the kind of speaker or you might have, I think that you did not tell that way.
Simply thinking about operation of the speaker depending on magnet field to be created from electric motor.
We can hear anything (music) from the speaker without magnet ? I am sure that voice coil will be damaged soon when supplying power for it. So we need to measure anything ?
It is only speaker, FC speaker at all !
Thanks.
I read the whole thread, took several days 
Interesting builds several on here have going.
Hentai, I have a spreadsheet here:
http://www.diyaudio.com/forums/multi-way/17936-diy-dynamic-driver-9.html
and it would be interesting to see how well it works with your build data?
I seem to be able to duplicate manufacturer T/S pretty well, but I don't have actual info on wire diameters and gap strength in most cases, so there are a few degrees of freedom with which I can fudge.
Interesting builds several on here have going.
Hentai, I have a spreadsheet here:
http://www.diyaudio.com/forums/multi-way/17936-diy-dynamic-driver-9.html
and it would be interesting to see how well it works with your build data?
I seem to be able to duplicate manufacturer T/S pretty well, but I don't have actual info on wire diameters and gap strength in most cases, so there are a few degrees of freedom with which I can fudge
.OK - I haven't used any field-coil speaker for decades (the last ones were mounted in old tube radios that I repaired as an apprentice). But I can tell you for sure that such a field coil's inductance is high enough that it would need a very big effort to modulate the current through this coil by the amount that you are claiming (neither through the voice-coil current nor through reasonably high voltage ripples on the field-coils supply voltage).
While the "old" field-coil drivers were built using that principle for reasons of economy and feasibility (lack of magnetic material, co-usage of field-coil for PSU ripple suppression), today's field coil drivers use this principle for exactly the reason of generating a very "stiff" magnetic field.
Regards
Charles
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I tried to offer some insights on how to size the steel in motor. Its based on my study and experience and thus if you find any errors please let me know.
PROJECT RYU Sizing Steel Parts for Field Coil Loudspeaker Motors
also here is a facebook page where i post updates:
https://www.facebook.com/Project-Ryu-442375812514399/
PROJECT RYU Sizing Steel Parts for Field Coil Loudspeaker Motors
also here is a facebook page where i post updates:
https://www.facebook.com/Project-Ryu-442375812514399/
Hi, yep that is always a problem. What i found is that it best to talk to steel works shops or factories and not raw material suppliers. Many times they sell material they have in excess and in smaller quantities.
If you know a factory manufacturing electromagnets or electrical motors that would be my first option.
If you know a factory manufacturing electromagnets or electrical motors that would be my first option.
Hi all,
Well, I finally got some time to put into the project his past week and set to the task of winding my field coils. This was my first version:
Now, I know what you're thinking Allar88... It looks a lot like "made by hand".
I thought so too. So, I took the time to make a simple winding assembly and gave it another try. That turned out like this:
Much better. 1475 turns, 19 layers. I wrapped the outside, top and bottom with gaffers tape. Although, even with a winding jig I may require reconstructive surgery for my poor wrists... they are sore. Here's the resistance, it bounces between 7.9 and 8.0 for this one, and between 7.8 and 7.9 for the other:
Will that disparity between them make much of a difference? Let me know if so - I can easily pull a few windings off of one of them until I get an exact match.
FieldCoil - I admire the uncompromising quality in your choice of power supplies, but I've opted for something cheaper. They look suspiciously like the supplies Hentai has pictured in his work (although the readings on these are digital). I can always upgrade to something better should I ever earn the right to have that problem.
I don't know what a reasonable power requirement is for a field coil of this size - I'd be most grateful for your recommendations. I ran one of them at 2.4A and 18V a couple of days ago (although I suspect that's way, way too much power). It remained reasonably cool for an hour, but at 90 minutes I shut it off because the motor had become very hot to the touch. I don't know the flux density in the gap either, and I haven't tried working in FEMM yet. Should I pick up a Gaussmeter, or is that unnecessary?
I have wire arriving tomorrow for the voice coil, I went with 0.1426mm. I've made a first cone to try out as well - it's nomex and weighs 5g. I plan to make the first former out of nomex, as well. I'd love to try mulberry or washi for both. Thin wood veneer is also tempting to try out. Tomorrow, I'll order some cloth surrounds and spiders from MAT Electronics for my first prototypes, although I plan to try my hand at making those eventually as well. It seems like cloth treated with butyl rubber that has been thinned down with toluene would work... for surrounds in any case.
Well, I finally got some time to put into the project his past week and set to the task of winding my field coils. This was my first version:
Now, I know what you're thinking Allar88... It looks a lot like "made by hand".
I thought so too. So, I took the time to make a simple winding assembly and gave it another try. That turned out like this:
Much better. 1475 turns, 19 layers. I wrapped the outside, top and bottom with gaffers tape. Although, even with a winding jig I may require reconstructive surgery for my poor wrists... they are sore. Here's the resistance, it bounces between 7.9 and 8.0 for this one, and between 7.8 and 7.9 for the other:
Will that disparity between them make much of a difference? Let me know if so - I can easily pull a few windings off of one of them until I get an exact match.
FieldCoil - I admire the uncompromising quality in your choice of power supplies, but I've opted for something cheaper. They look suspiciously like the supplies Hentai has pictured in his work (although the readings on these are digital). I can always upgrade to something better should I ever earn the right to have that problem.
I don't know what a reasonable power requirement is for a field coil of this size - I'd be most grateful for your recommendations. I ran one of them at 2.4A and 18V a couple of days ago (although I suspect that's way, way too much power). It remained reasonably cool for an hour, but at 90 minutes I shut it off because the motor had become very hot to the touch. I don't know the flux density in the gap either, and I haven't tried working in FEMM yet. Should I pick up a Gaussmeter, or is that unnecessary?
I have wire arriving tomorrow for the voice coil, I went with 0.1426mm. I've made a first cone to try out as well - it's nomex and weighs 5g. I plan to make the first former out of nomex, as well. I'd love to try mulberry or washi for both. Thin wood veneer is also tempting to try out. Tomorrow, I'll order some cloth surrounds and spiders from MAT Electronics for my first prototypes, although I plan to try my hand at making those eventually as well. It seems like cloth treated with butyl rubber that has been thinned down with toluene would work... for surrounds in any case.
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Hi Gomper,
I have been busy in recently. So for a long time, I have not time much more to visit this topic.
Almostly two month that you post some information in here, how about your project ?
I think your power supply are work well. The way to choice power supply like this one is the best way for FC project beginner. Then they can test and check everything for their project , especially in control the votage supply for FC system .
I also spent more time and more power to make winding coils in my project by hand. All my body to be sore for several days after finish these coils completely.
I also think the difference a little bit between resistance of winding coils is not affect magnetic field much more.
In my past FC projects, widing coils resistance to be measured from 15.6 Ohms to 17.6 Ohms, wire diameter 20 AWG, voltage at 17 VDC to 24 VDC (depend on each type of project , FC Bass : 17.3 ohms – 16.8 VDC ; FC Mid : 17.6 ohms – 24 VDC ; FC Trebe : 15.6 ohms – 16.8 VDC).
Now , I can calculate coils winding with 24 VDC power supply.
You should decrease power suppy with 14 VDC or 15 VDC, and test the FC for a long time again (more than 3 hours), to know whether the motor to be become hot in touch. If it will be hot, you should check the materials of housing or motor construction.
I took a picture more than 3 years ago, in testing the FC Trebe was extending 6 hours , the motor just only warmed up. Sound output is very good.
Hope, you are pleased and enjoy with your project.
FieldCoil Adventure.
I have been busy in recently. So for a long time, I have not time much more to visit this topic.
Almostly two month that you post some information in here, how about your project ?
I think your power supply are work well. The way to choice power supply like this one is the best way for FC project beginner. Then they can test and check everything for their project , especially in control the votage supply for FC system .
I also spent more time and more power to make winding coils in my project by hand. All my body to be sore for several days after finish these coils completely.
I also think the difference a little bit between resistance of winding coils is not affect magnetic field much more.
In my past FC projects, widing coils resistance to be measured from 15.6 Ohms to 17.6 Ohms, wire diameter 20 AWG, voltage at 17 VDC to 24 VDC (depend on each type of project , FC Bass : 17.3 ohms – 16.8 VDC ; FC Mid : 17.6 ohms – 24 VDC ; FC Trebe : 15.6 ohms – 16.8 VDC).
Now , I can calculate coils winding with 24 VDC power supply.
You should decrease power suppy with 14 VDC or 15 VDC, and test the FC for a long time again (more than 3 hours), to know whether the motor to be become hot in touch. If it will be hot, you should check the materials of housing or motor construction.
I took a picture more than 3 years ago, in testing the FC Trebe was extending 6 hours , the motor just only warmed up. Sound output is very good.
Hope, you are pleased and enjoy with your project.
FieldCoil Adventure.
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Hey FieldCoil! Thanks for checking in - I have been so busy with work that I haven't had time to devote to the project lately. Thanks so much for sharing your measurements and recommendations, I really appreciate it.
This weekend I'll be making my first voice coils. I've made a winding assembly for them using a chrome plated steel bar, as was recommended by Jim Lahey. My plan is for a dual coil with a shorted inner winding, and I'll be trying out washi paper for the former material. Wish me luck.
What a beautiful driver you've got there. Did you make the horn?
This weekend I'll be making my first voice coils. I've made a winding assembly for them using a chrome plated steel bar, as was recommended by Jim Lahey. My plan is for a dual coil with a shorted inner winding, and I'll be trying out washi paper for the former material. Wish me luck.
What a beautiful driver you've got there. Did you make the horn?
Hi Gomper,
Thank for your comment, Hope you will be successful with your speaker.
I am deeply impressed by yourself voice coil making. I made all parts of those driver excepted paper cones and voice coils. To me, this is a very hard work, it need to be made from professional fields . I only buy voice coils, papercones in the market.
I think , the voice coil which is described by you will be a special thing. Please take some pictures to share in here.
You can try with DC power supply to be regulated by Selenium rectifier, after you test your drivers and fix the DC voltage, you should make the kink of power supply to test again. It will be interesting for you.
I bought the pair of horn in my town and made adaptor myself, one time when I searched to look for some thing on internet, I found and bought them with it's price more than 100$.
Good luck, Gomper.
FieldCoil Adventure
Thank for your comment, Hope you will be successful with your speaker.
I am deeply impressed by yourself voice coil making. I made all parts of those driver excepted paper cones and voice coils. To me, this is a very hard work, it need to be made from professional fields . I only buy voice coils, papercones in the market.
I think , the voice coil which is described by you will be a special thing. Please take some pictures to share in here.
You can try with DC power supply to be regulated by Selenium rectifier, after you test your drivers and fix the DC voltage, you should make the kink of power supply to test again. It will be interesting for you.
I bought the pair of horn in my town and made adaptor myself, one time when I searched to look for some thing on internet, I found and bought them with it's price more than 100$.
Good luck, Gomper.
FieldCoil Adventure
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