Hello. I am assembling 3 way crossover for stereo project.
I require air wound inductors of mH values of say 1 - 4mH. Exact values are not important here.
I have source of cheap (free) 20AWG wire (0.8mm). The DC resistance will be quite high in this case. I am building 12dB / Octave design. One inductor is in series with woofer so I would like to keep its DC resistance low for efficiency.
Question is, if I loosely twist 2 0.8mm conductors (with cordless drills assistance) in parallel and wind the inductor, Is this possible? I am looking for less than 1/10th Ω of woofer (less than 0.8Ω).
I am raiding an old F&P smartdrive washing machine motor of it's copper, if this helps anyone.
Thanks for any advice!
ps. I have made 4 x 0.36uH inductors quite happily using 0.8mm wire. I also have good (kit built Silicone Chip mag) inductance meter at hand.
Thank you. (I hope winding two conductors wont add any capacitance / inductance, causing a complex circuit etc). I am just trying to save some $$$ and have fun.
I require air wound inductors of mH values of say 1 - 4mH. Exact values are not important here.
I have source of cheap (free) 20AWG wire (0.8mm). The DC resistance will be quite high in this case. I am building 12dB / Octave design. One inductor is in series with woofer so I would like to keep its DC resistance low for efficiency.
Question is, if I loosely twist 2 0.8mm conductors (with cordless drills assistance) in parallel and wind the inductor, Is this possible? I am looking for less than 1/10th Ω of woofer (less than 0.8Ω).
I am raiding an old F&P smartdrive washing machine motor of it's copper, if this helps anyone.
Thanks for any advice!
ps. I have made 4 x 0.36uH inductors quite happily using 0.8mm wire. I also have good (kit built Silicone Chip mag) inductance meter at hand.
Thank you. (I hope winding two conductors wont add any capacitance / inductance, causing a complex circuit etc). I am just trying to save some $$$ and have fun.
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Here is a commercial product: https://www.intertechnik.com/Shop/Cross-over-parts/Inductors/Tritec-Hexagonal-AWG10-15/1768,en,80
IMHO, a 1mH air core does make sense, but a 4mH one not.
Ralf
IMHO, a 1mH air core does make sense, but a 4mH one not.
Ralf
Thanks. I have wound 20AWG (0.8mm) wire and created 4 x 0.36mH aircore inductors (for 2nd order crossover, tweeter HP and mid BP) as well as 2 x 0.25mH (for my 1st order crossover) aircore inductors. Size is about 1 inch (25mm) diameter and height is less, which is respectible. My hands hurt now!
"Litz"windings is to lessen (eliminate) skin effect at microwave (RF) frequencies. I was concerned about complicating things at audio frequencies, namely non linearity! I desire good sound using home made components (personal, hobby use!)
Thanks jcx.
Mr. giralfino, why does making 4mH one not make sense? I guess making 4mH inductor would be about 10 times the size of a 0.4mH one? I understand it has to do with 'turns ratio'. I am guessing that DC resistance would be higher, due to 10 (?) times the number of turns. That would make 0.7Ω become 7Ω, which would be high ??? (8Ω + 7Ω = 15Ω)
May be I am missing something ? I am trying to AVOID iron core.
"Litz"windings is to lessen (eliminate) skin effect at microwave (RF) frequencies. I was concerned about complicating things at audio frequencies, namely non linearity! I desire good sound using home made components (personal, hobby use!)
Thanks jcx.
Mr. giralfino, why does making 4mH one not make sense? I guess making 4mH inductor would be about 10 times the size of a 0.4mH one? I understand it has to do with 'turns ratio'. I am guessing that DC resistance would be higher, due to 10 (?) times the number of turns. That would make 0.7Ω become 7Ω, which would be high ??? (8Ω + 7Ω = 15Ω)
May be I am missing something ? I am trying to AVOID iron core.
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"with 7 twisted, solitary insulated copper conductors"
That sounds cool.
Yes, I understand DC and AC theory, although AC makes my head Hertz (joke!)
Impedance comprises of C and R components... Thanks.
So, winding 7 x 20AWG wires in parallel and winding on rather large bobbin would work to my needs ?? I may have to work out series resistances of 7 x conductors (or what have I). ...I would like < 0.8Ω if possible (< 0.4Ω for the Z = 4Ω setup.
am I on the right track? Or is higher DC Ω acceptable for 'average' system? (Obviously less is more)
I am making two setups, one with one 12" woofer Z = 8Ω and the other speakers use 2 x 8Ω 10" wired in parallel (in phase of course
)
Thanks.
That sounds cool.
Yes, I understand DC and AC theory, although AC makes my head Hertz (joke!)
Impedance comprises of C and R components... Thanks.
So, winding 7 x 20AWG wires in parallel and winding on rather large bobbin would work to my needs ?? I may have to work out series resistances of 7 x conductors (or what have I). ...I would like < 0.8Ω if possible (< 0.4Ω for the Z = 4Ω setup.
am I on the right track? Or is higher DC Ω acceptable for 'average' system? (Obviously less is more)
I am making two setups, one with one 12" woofer Z = 8Ω and the other speakers use 2 x 8Ω 10" wired in parallel (in phase of course
)Thanks.
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Twisting together 2x20AWG wires is equivalent to a single 17AWG wire. The inductance of a coil is dependent on the wire itself but also on the geometry of the coil, but expect to have a DCR of roughly 1 Ohm for a 4mH coil (*).
High DCR coils are not bad per se, but that means that some power will be wasted as heat and not passed to drivers (if a driver is in series to this coil). If a coil is in series to a midrange in a 3-way the DCR of the coil has to be summed to the resistance of a highly-to-be-there resistor, so probably not a problem, but if the coil is in series to a woofer, that DCR has to be low in order not to loose SPL.
And then there is the weight factor. Comparing two 3.3mH coils from the same manufacturer (Jantzen), the iron core coil uses 1.0 mm wire, has a DCR of 0.36 Ohm, and weights 225 g, while the air core with 1.6 mm wire has a DCR of 0.48 Ohm (still good but higher than the iron core), and weights 1Kg.
An iron core is not a devil, chosen right is the only sensible choice for a high inductance coil.
Ralf
(*) If your winding technology is good ...
High DCR coils are not bad per se, but that means that some power will be wasted as heat and not passed to drivers (if a driver is in series to this coil). If a coil is in series to a midrange in a 3-way the DCR of the coil has to be summed to the resistance of a highly-to-be-there resistor, so probably not a problem, but if the coil is in series to a woofer, that DCR has to be low in order not to loose SPL.
And then there is the weight factor. Comparing two 3.3mH coils from the same manufacturer (Jantzen), the iron core coil uses 1.0 mm wire, has a DCR of 0.36 Ohm, and weights 225 g, while the air core with 1.6 mm wire has a DCR of 0.48 Ohm (still good but higher than the iron core), and weights 1Kg.
An iron core is not a devil, chosen right is the only sensible choice for a high inductance coil.
Ralf
(*) If your winding technology is good ...
"
Originally Posted by Butcher
I guess making 4mH inductor would be about 10 times the size of a 0.4mH one? I understand it has to do with 'turns ratio'. I am guessing that DC resistance would be higher, due to 10 (?) times the number of turns."
"More like 3 or 4 times"
Not sure if you serious or not But they are big buggers!
It is nice to recycle perfectly good 99.9% (?) copper that was just thrown out. Good old washing machines! TV degaus (sp) coils are mostly 0.5mm D.
20-17 Gauge makes sense.
"If your winding technology is good ..."
Cheeky bugger! I read about hex windings. Stacking windings 2, then 4, then 2. Yea, might need some practice Mr. Ralf! Um, 2 + 4+ 2 = 8. Please explain hex windings. I understand that winding thus is to fill spool with max turns ... ? I am being lazy
I have AWG - mm D chart. Very interesting. I can spot pattern
1 ohm is acceptable. I now understand that the 3.6mH (Which I chose,,See below) needs to be low DC resistance for W (Woofer). this is current law, mmm, Mr, ohm, right??? Midrange not so fussy because of V Av. -Much more polarity changes...
Resistors loose energy thru heat. (So to capacitors and inductors...)
"highly-to-be-there resistor" Yes, inherent R !
"And then there is the weight factor."
Not a problem! These buggers are heavy, I take it (soon to wind one!). I will ask my mate to help. Cordless drill etc. Best way to straighten wire is with one turn around a smooth object. I settled on plastic screwdriver handle. Use about 0.9 turns and common sense!
"Comparing"
I like the way you think. establishes baseline!
"An iron core is not a devil, chosen right is the only sensible choice for a high inductance coil."
Well, permeability? would one choose bunch of old rusty nails??? I am being serious! I am aware of laminated sheets that act to prevent eddy losses?
I would like big damn 1.8mH and 3.6mH coils! Expense is no prob. My buddy made His own speaker boxes that are 1500mm high and allow for much room behind woofers, using recycled Remu wood (native NZ timber).
Link...
https://en.wikipedia.org/wiki/Dacrydium_cupressinum
I am no carpenter, but I would like to see this homemade system perform for His '80 's music!
Originally Posted by Butcher
I guess making 4mH inductor would be about 10 times the size of a 0.4mH one? I understand it has to do with 'turns ratio'. I am guessing that DC resistance would be higher, due to 10 (?) times the number of turns."
"More like 3 or 4 times"
Not sure if you serious or not
But they are big buggers!It is nice to recycle perfectly good 99.9% (?) copper that was just thrown out. Good old washing machines! TV degaus (sp) coils are mostly 0.5mm D.
20-17 Gauge makes sense.
"If your winding technology is good ..."
Cheeky bugger! I read about hex windings. Stacking windings 2, then 4, then 2. Yea, might need some practice Mr. Ralf! Um, 2 + 4+ 2 = 8. Please explain hex windings. I understand that winding thus is to fill spool with max turns ... ? I am being lazy
I have AWG - mm D chart. Very interesting. I can spot pattern
1 ohm is acceptable. I now understand that the 3.6mH (Which I chose,,See below) needs to be low DC resistance for W (Woofer). this is current law, mmm, Mr, ohm, right??? Midrange not so fussy because of V Av. -Much more polarity changes...
Resistors loose energy thru heat. (So to capacitors and inductors...)
"highly-to-be-there resistor" Yes, inherent R !
"And then there is the weight factor."
Not a problem! These buggers are heavy, I take it (soon to wind one!). I will ask my mate to help. Cordless drill etc. Best way to straighten wire is with one turn around a smooth object. I settled on plastic screwdriver handle. Use about 0.9 turns and common sense!
"Comparing"
I like the way you think. establishes baseline!
"An iron core is not a devil, chosen right is the only sensible choice for a high inductance coil."
Well, permeability? would one choose bunch of old rusty nails??? I am being serious! I am aware of laminated sheets that act to prevent eddy losses?
I would like big damn 1.8mH and 3.6mH coils! Expense is no prob. My buddy made His own speaker boxes that are 1500mm high and allow for much room behind woofers, using recycled Remu wood (native NZ timber).
Link...
https://en.wikipedia.org/wiki/Dacrydium_cupressinum
I am no carpenter, but I would like to see this homemade system perform for His '80 's music!
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Hi Butcher, Here is an easier way of obtaining coils and whatever else you may need.
I hope this helps.
SpeakerBug
C.M
I hope this helps.
SpeakerBug
C.M
Hi Tweet!
Yea I bought set of crossover boards from Jaycar about 8 years ago. Populated with PPE dielectric caps and wound half of the inductors.
I am also after advice in low inductance resistors. I have measured resistors of 2 ohms and discovered high inductance. I admit that most of this is caused by BS by not factorising R.
Here in NZ there is not much choice of 'splurging' into components.
Thanks Tweet! Nice to meet etc.
I can take photos of current (bad pun) setup. I appreciate all your help !
...gonna make high Z inductors, if it urgs (bad pun) me!
Size doesn't matter too much. Balance between size and insulation does.
Yea I bought set of crossover boards from Jaycar about 8 years ago. Populated with PPE dielectric caps and wound half of the inductors.
I am also after advice in low inductance resistors. I have measured resistors of 2 ohms and discovered high inductance. I admit that most of this is caused by BS by not factorising R.
Here in NZ there is not much choice of 'splurging' into components.
Thanks Tweet! Nice to meet etc.
I can take photos of current (bad pun) setup. I appreciate all your help !
...gonna make high Z inductors, if it urgs (bad pun) me!
Size doesn't matter too much. Balance between size and insulation does.
Inductance varies as the number of turns squared, so it only takes twice as many turns to get 4x inductance.
If you are winding your own, you can use a railroad spike or 1008 (low carbon) steel bar stock (even bundled nails might work in a pinch) and get roughly 4x the inductance. I think iron core like to have fewer layers with more turns per layer.
I would use at least 3 strands of wire, as that is more space efficient than 2.
Thanks Ron E.
I am not concerned about space or size of inductors. My personal speaker box is 60L. My friends ones are much larger volume than that. Inductors will be mounted securely.
Again, I am trying to avoid iron cores. I have lots of free 0.8mm diameter copper wire. I will look into winding may be three strands of 0.8mm in parallel. Thanks.
Few questions, how tightly should I wind the three strands?
Also, any ideas on material for bobbin? I am thinking PVC pipe with wooden disks for ends. The discs I can cut out using a wood hole cutter.
I will take some photos of progress so far.
By the way, I have chosen cutoff points as, 500Hz and 5KHz.
I am not concerned about space or size of inductors. My personal speaker box is 60L. My friends ones are much larger volume than that. Inductors will be mounted securely.
Again, I am trying to avoid iron cores. I have lots of free 0.8mm diameter copper wire. I will look into winding may be three strands of 0.8mm in parallel. Thanks.
Few questions, how tightly should I wind the three strands?
Also, any ideas on material for bobbin? I am thinking PVC pipe with wooden disks for ends. The discs I can cut out using a wood hole cutter.
I will take some photos of progress so far.
By the way, I have chosen cutoff points as, 500Hz and 5KHz.
Short answer and nor digressing like some of the contradicting advice above.
1) do not twist them, no need to and in fact it increases total resistance
2) all turns must have the exact same number of turns and be wound around same axis (which may be some kind of magnetic one or simply air/vacuum)
3) one way to guarantee that is to wind many strands at the same time.
No need for the pack to be roughly circular, it may naturally form a rough "ribbon" when held by your guiding hand, no big deal.
4) in that case, inductance will come mainly from amount of turns, and core diameter , while DC resistance will be directly proportional to wire length and inversely proportional to number of strands in parallel, which will dictate equivalent wire section.
Source: I commercially design , wind and sell Musical Instrument transformers, both Power and Output types, and often rely on multiple windings of easier to wind thinner wire, which are later put in parallel.
1) do not twist them, no need to and in fact it increases total resistance
2) all turns must have the exact same number of turns and be wound around same axis (which may be some kind of magnetic one or simply air/vacuum)
3) one way to guarantee that is to wind many strands at the same time.
No need for the pack to be roughly circular, it may naturally form a rough "ribbon" when held by your guiding hand, no big deal.
4) in that case, inductance will come mainly from amount of turns, and core diameter , while DC resistance will be directly proportional to wire length and inversely proportional to number of strands in parallel, which will dictate equivalent wire section.
Source: I commercially design , wind and sell Musical Instrument transformers, both Power and Output types, and often rely on multiple windings of easier to wind thinner wire, which are later put in parallel.
If you need to calculate inductors look for '' weeler formula'' & '' brooks coil ''.
But if you need to make stranded wire DO NOT US A DRILL it is not the way to go .
With a drill the wires will not only wrap aroud each other ... they will twist ... if you make a stranded wire with several small wires and twist them together with a drill and make 300 turns ... each wire will also have make 300 turns on themself ..and this will damage the wire .
But if you need to make stranded wire DO NOT US A DRILL it is not the way to go .
With a drill the wires will not only wrap aroud each other ... they will twist ... if you make a stranded wire with several small wires and twist them together with a drill and make 300 turns ... each wire will also have make 300 turns on themself ..and this will damage the wire .
Hi Butcher, me again, I though you were in Australia, a mix up with the flags.
Heavens, they should just build a bridge between the two countries and be done with it.
In regard to non-inductive resistors you could use the nichrome wire in those old electric jug elements (the porcelain insulator type), just wind the wire in one direction then in the other with the proviso of insulating one layer from the other.
Actually, non-inductive resistors generally provide very little benefit in passive crossovers because the audio frequencies are too low, any inductive reactance of a normal wire wound resistor likewise is essentially trivial at audio frequencies so making your own is likely to have inaudible results.
If you were to make an iron cored inductor it is best not to use nails or ordinary iron parts as they tend to have high retentivity and poor permeability. Audio transformer cores are best suited for the purpose if you decide to make your own laminated iron core inductors. Just a few thoughts.
C.M
Heavens, they should just build a bridge between the two countries and be done with it.
In regard to non-inductive resistors you could use the nichrome wire in those old electric jug elements (the porcelain insulator type), just wind the wire in one direction then in the other with the proviso of insulating one layer from the other.
Actually, non-inductive resistors generally provide very little benefit in passive crossovers because the audio frequencies are too low, any inductive reactance of a normal wire wound resistor likewise is essentially trivial at audio frequencies so making your own is likely to have inaudible results.
If you were to make an iron cored inductor it is best not to use nails or ordinary iron parts as they tend to have high retentivity and poor permeability. Audio transformer cores are best suited for the purpose if you decide to make your own laminated iron core inductors. Just a few thoughts.
C.M
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