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Crossover Inductors and Coil Bobbins for Loudspeakers

Article:  Crossover inductors Part 1

Article:  Crossover inductors Part 2

      Review and buy your crossover inductors here. Choose from a comprehensive selection of crossover inductors and coil bobbins for loudspeaker projects. These range from air-core and ferrite coil bobbins through to custom wound inductors for speaker projects. Ferrite Inductors are available in six different bobbin sizes which, along with selected wire diameters, allows for the best optimisation of your crossover board layout.
        Thick 1.3mm diameter wire wound on large ferrite bobbins provide for high power handling and low DCR values. Alternatively, smaller diameter wires offer higher inductance values but with an increased DCR due to the increased length of wire used.
        All crossover inductors are wound to order and can be supplied to custom values if needed.

Ferrite Cored Coil Bobbins

Ferrite Bobbin Cores

Six sizes of Ferrite Cored Coil Bobbins are offered and suitable for winding custom value crossover inductors as typically used in loudspeakers. Designated as Type A through to G.
A 'guide' to usage is as follows:-

Type A: FBA1823 Small value Inductors for Tweeter frequency modifications / tweeks.
Type B: FBB2728 Low power Bass and Tweeter crossovers to 50w rms max. system power.
Type C: FBC2535 Medium power Bass and Tweeter crossovers to 80w rms maximum system power.
Type E, FBE3050, FBF3556 and FBG6256 Medium power Bass and Tweeter crossovers to 100w rms max. system power.
Types F and G use large sized Bobbins and depending upon wire gauge can be targeted at High inductance values OR High Power.

NOTE (1): The wire used for the coil winding is specified both in wire diameter and cross-sectional area, otherwise abbreviated to CSA. This information is provided for reference.

NOTE (2): All DCR values are calculated values based upon wire length and diameter.

NOTE (3): Intermediate crossover inductor values can be supplied to order, priced at the next higher inductance value.

* Ferrite Core Bobbins. All dims mm are approximate
Order Code Type Max Diam Max Ht Core Diam Core Ht 1+
FBA1823 A 23 18 13 12 0.93 /ea
FBB2728 B 28 27 17 18 1.82 /ea
FBC2535 C 35 25 20 17 2.35 /ea
FBE3050 E 50 30 25 20 5.40 /ea
FBF3556 F 56 35 33 25 4.99 /ea
FBG6256 G 56 62 34 52 13.99 /ea

Ferrite Core Inductors

      There are a large number of ferrite cored coil bobbins available. These all vary in terms of shape, ferrite material, bobbin weight and size. If you are looking for a crossover inductor to replace an existing component then it's important to match the mechanical features as well as the electrical ones. Often there is little information on the defective inductor to aid this task. We have provided as much mechanical information as is reasonable to help identify the bobbin features. The details are all as listed in the above table.

Ferrite Inductors Type B Bobbin, FBB Series

Small Crossover Inductors with a Ferrite Core

FBB Series  1.0 mm wire,  CSA 0.78 sq mm,  Diam. 28mm,  Height 27mm,   Priced Each
Order Code Spec. 10% 5% 2%
  Type B Bobbin  1.0mm wire      
FBB10 0.10mH, 1.0mm Wire, DCR 0.040 Ohms 4.62 5.08 5.54
FBB15 0.15mH, 1.0mm Wire, DCR 0.051 Ohms 4.67 5.15 5.61
FBB18 0.18mH, 1.0mm Wire, DCR 0.056 Ohms 4.70 5.18 5.65
FBB22 0.22mH, 1.0mm Wire, DCR 0.062 Ohms 4.73 5.20 5.67
FBB25 0.25mH, 1.0mm Wire, DCR 0.066 Ohms 4.76 5.23 5.71
FBB27 0.27mH, 1.0mm Wire, DCR 0.070 Ohms 4.79 5.27 5.74
 
FBB30 0.30mH, 1.0mm Wire, DCR 0.074 Ohms 4.82 5.30 5.78
FBB33 0.33mH, 1.0mm Wire, DCR 0.079 Ohms 4.85 5.33 5.82
FBB39 0.39mH, 1.0mm Wire, DCR 0.088 Ohms 4.87 5.36 5.85
FBB42 0.42mH, 1.0mm Wire, DCR 0.094 Ohms 4.90 5.40 5.88
FBB47 0.47mH, 1.0mm Wire, DCR 0.099 Ohms 4.92 5.42 5.91
FBB51 0.51mH, 1.0mm Wire, DCR 0.105 Ohms 4.96 5.45 5.94
FBB56 0.56mH, 1.0mm Wire, DCR 0.110 Ohms 4.99 5.49 5.96
FBB60 0.60mH, 1.0mm Wire, DCR 0.114 Ohms 5.02 5.52 6.03

Ferrite Inductors Type C Bobbin, FBC Series

Crossover Inductors with Medium Ferrite Core

FBC Series  1.0 mm wire,  CSA  0.78 sq mm,  Diam. 35mm, Height 25mm,   Priced Each
Order Code Spec. 10% 5% 2%
  Type C Bobbin  1.0mm wire Tols 10% 5% 2%
FBCQ10 0.10mH, 1.0mm Wire, DCR 0.04 Ohms 5.24 5.76 6.29
FBCQ15 0.15mH, 1.0mm Wire, DCR 0.05 Ohms 5.29 5.82 6.35
FBCQ20 0.20mH, 1.0mm Wire, DCR 0.06 Ohms 5.34 5.88 6.41
FBCQ22 0.22mH, 1.0mm Wire, DCR 0.06 Ohms 5.45 5.99 6.54
FBCQ33 0.33mH, 1.0mm Wire, DCR 0.08 Ohms 5.60 6.15 6.72
FBCQ47 0.47mH, 1.0mm Wire, DCR 0.10 Ohms 5.71 6.28 6.86
FBCQ56 0.56mH, 1.0mm Wire, DCR 0.11 Ohms 5.81 6.39 6.98
FBCQ68 0.68mH, 1.0mm Wire, DCR 0.12 Ohms 5.85 6.55 7.01
FBCQ75 0.75mH, 1.0mm Wire, DCR 0.125 Ohms 6.03 6.63 7.23
FBCQ82 0.82mH, 1.0mm Wire, DCR 0.13 Ohms 6.09 6.70 7.31
FBCQ91 0.91mH, 1.0mm Wire, DCR 0.14 Ohms 6.16 6.78 7.39
FBCQ100 1.00mH, 1.0mm Wire, DCR 0.15 Ohms 6.22 6.84 7.47


FBC Series  0.8mm wire,   CSA 0.50 sq mm  Diam. 35mm, Height 25mm,   Priced each.
Order Code Spec. 10% 5% 2%
  Type C Bobbin  0.8mm wire Tols 10% 5% 2%
FBCT47 0.47mH, 0.8mm Wire, DCR 0.14 Ohms 5.44 5.99 6.52
FBCT56 0.56mH, 0.8mm Wire, DCR 0.16 Ohms 5.52 6.06 6.63
FBCT68 0.68mH, 0.8mm Wire, DCR 0.17 Ohms 5.53 6.09 6.64
FBCT75 0.75mH, 0.8mm Wire, DCR 0.18 Ohms 5.57 6.12 6.68
FBCT82 0.82mH, 0.8mm Wire, DCR 0.19 Ohms 5.59 6.14 6.70
FBCT91 0.91mH, 0.8mm Wire, DCR 0.21 Ohms 5.62 6.17 6.74
FBCT10 1.00mH, 0.8mm Wire, DCR 0.22 Ohms 5.68 6.25 6.81
FBCT12 1.20mH, 0.8mm Wire, DCR 0.24 Ohms 5.88 6.47 7.06
FBCT15 1.50mH, 0.8mm Wire, DCR 0.27 Ohms 5.92 6.51 7.10
FBCT18 1.80mH, 0.8mm Wire, DCR 0.31 Ohms 6.05 6.66 7.26
FBCT22 2.20mH, 0.8mm Wire, DCR 0.35 Ohms 6.18 6.80 7.41
FBCT25 2.50mH, 0.8mm Wire, DCR 0.38 Ohms 6.36 7.00 7.78

Ferrite Inductors TYPE E Bobbin FBE Series

Large Ferrite Crossover Inductors

FBE Series  1.25 mm wire,  CSA 1.23 sq mm,  Diam. 50mm, Height 30mm,  Priced each.
Order Code Spec. 10% 5%
  Type E Bobbin,  1.25mm wire Tols 10% 5%
FBEQ10 1.00mH, 1.25mm Wire, DCR 0.09 Ohms 9.98 10.98
FBEQ15 1.50mH, 1.25mm Wire, DCR 0.11 Ohms 10.81 11.89
FBEQ18 1.80mH, 1.25mm Wire, DCR 0.13 Ohms 11.19 12.31
FBEQ20 2.00mH, 1.25mm Wire, DCR 0.14 Ohms 11.41 12.55
FBEQ25 2.50mH, 1.25mm Wire, DCR 0.15 Ohms 12.01 13.21
FBEQ27 2.70mH, 1.25mm Wire, DCR 0.16 Ohms 12.21 13.43
FBEQ30 3.00mH, 1.25mm Wire, DCR 0.18 Ohms 12.62 13.88
FBEQ33 3.30mH, 1.25mm Wire, DCR 0.19 Ohms 12.92 14.21
FBEQ39 3.90mH, 1.25mm Wire, DCR 0.21 Ohms 13.64 15.00
FBEQ42 4.20mH, 1.25mm Wire, DCR 0.23 Ohms 13.97 15.37
FBEQ47 4.70mH, 1.25mm Wire, DCR 0.24 Ohms 14.52 15.97


 FBE Series  1.12 mm wire,  CSA 0.985 sq mm   Diam. 50mm, Height 30mm,   Priced each.
Order Code Spec. 10% 5%
  Type E Bobbin,  1.12mm wire Tols 10% 5%
FBET20 2.00mH, 1.12mm Wire, DCR 0.17 Ohms 10.64 11.70
FBET22 2.20mH, 1.12mm Wire, DCR 0.18 Ohms 10.97 12.06
FBET25 2.50mH, 1.12mm Wire, DCR 0.19 Ohms 11.11 12.22
FBET27 2.70mH, 1.12mm Wire, DCR 0.21 Ohms 11.30 12.43
FBET30 3.00mH, 1.12mm Wire, DCR 0.22 Ohms 11.60 12.76
FBET33 3.30mH, 1.12mm Wire, DCR 0.23 Ohms 11.74 12.91
FBET39 3.90mH, 1.12mm Wire, DCR 0.26 Ohms 12.43 13.67
FBET42 4.20mH, 1.12mm Wire, DCR 0.28 Ohms 12.70 13.97
FBET47 4.70mH, 1.12mm Wire, DCR 0.30 Ohms 12.92 14.21

     Are you building that LF Bass speaker enclosure and can't or don't want to use "Active" crossovers"? Then the following Inductors wound on a larger size Ferrite bobbin may just be the answer. Larger Bobbins for higher inductances and / or thicker wire for higher power.

Ferrite Inductors TYPE F Bobbin FBF Series

Ferrite Cored Crossover Inductors Type F

FBF Series  1.32 mm wire,  CSA 1.38 sq mm,  Diam. 56mm, Height 35mm,   Priced each.
Order Code Spec. 10% 5%
  Type F Bobbin,  1.32mm Wire Tols 10% 5%
FBFQ10 1.0mH, 1.32mm Wire, DCR 0.10 Ohms 10.17 11.18
FBFQ15 1.5mH, 1.32mm Wire, DCR 0.13 Ohms 11.19 12.31
FBFQ18 1.8mH, 1.32mm Wire, DCR 0.14 Ohms 11.63 12.79
FBFQ20 2.0mH, 1.32mm Wire, DCR 0.15 Ohms 12.04 13.24
FBFQ25 2.5mH, 1.32mm Wire, DCR 0.17 Ohms 12.84 14.12
FBFQ27 2.7mH, 1.32mm Wire, DCR 0.18 Ohms 13.22 14.66
FBFQ30 3.0mH, 1.32mm Wire, DCR 0.19 Ohms 13.69 15.05
FBFQ33 3.3mH, 1.32mm Wire, DCR 0.21 Ohms 14.19 15.61


FBF Series  1.25 mm wire,  CSA 1.23 sq mm ,  Diam. 56mm, Height 35mm,   Priced each.   
Order Code Spec. 10% 5%
  Type F Bobbin,  1.25mm Wire Tols 10% 5%
FBFT10 1.0mH, 1.25mm Wire, DCR 0.11 Ohms 9.76 10.74
FBFT15 1.5mH, 1.25mm Wire, DCR 0.14 Ohms 10.72 11.79
FBFT18 1.8mH, 1.25mm Wire, DCR 0.16 Ohms 11.22 12.34
FBFT20 2.0mH, 1.25mm Wire, DCR 0.17 Ohms 11.52 12.67
FBFT25 2.5mH, 1.25mm Wire, DCR 0.19 Ohms 12.21 13.43
FBFT27 2.7mH, 1.25mm Wire, DCR 0.20 Ohms 12.51 13.76
FBFT30 3.0mH, 1.25mm Wire, DCR 0.22 Ohms 12.93 14.22
FBFT33 3.3mH, 1.25mm Wire, DCR 0.23 Ohms 13.37 14.71
FBFT39 3.9mH, 1.25mm Wire, DCR 0.26 Ohms 14.36 15.79


FBF Series   1.0 mm wire,  CSA 0.78 sq mm,   Diam. 56mm, Height 35mm,   Priced each.   
Order Code Spec. 10% 5%
  Type F Bobbin,  1.0mm Wire Tols 10% 5%
FBFA39 3.9mH, 1.0mm Wire, DCR 0.36 Ohms 10.48 11.53
FBFA42 4.2mH, 1.0mm Wire, DCR 0.37 Ohms 10.95 12.05
FBFA47 4.7mH, 1.0mm Wire, DCR 0.40 Ohms 11.03 12.13
FBFA56 5.6mH, 1.0mm Wire, DCR 0.44 Ohms 11.53 12.68
FBFA68 6.8mH, 1.0mm Wire, DCR 0.49 Ohms 12.27 13.50
FBFA75 7.5mH, 1.0mm Wire, DCR 0.53 Ohms 12.77 14.25
FBFA82 8.2mH, 1.0mm Wire, DCR 0.59 Ohms 13.38 14.72
FBFA91 9.1mH, 1.0mm Wire, DCR 0.60 Ohms 13.62 14.98
FBFA100 10.0mH, 1.0mm Wire, DCR 0.64 Ohms 14.14 15.55

Ferrite Inductors TYPE G Bobbin, FBG Series:-  Diam. 56mm, Ht 62mm

High Power Large Crossover Inductors

High Power  FBG Series,  1.32 mm wire,  CSA 1.37 sq mm, Diam. 56mm, Ht 62mm,   Priced each
Order Code Spec. 10% 5%
  Type G Bobbin,  1.32mm Wire Tols 10% 5%
FBGQ56 5.6mH, 1.32mm Wire, DCR 0.27 Ohms 25.72 26.36
FBGQ62 6.2mH, 1.32mm Wire, DCR 0.29 Ohms 26.18 26.83
FBGQ69 6.8mH, 1.32mm Wire, DCR 0.30 Ohms 26.62 27.29
FBGQ75 7.5mH, 1.32mm Wire, DCR 0.32 Ohms 27.08 27.76
FBGQ82 8.2mH, 1.32mm Wire, DCR 0.34 Ohms 27.58 28.27
FBGQ91 9.1mH, 1.32mm Wire, DCR 0.37 Ohms 28.24 28.95
FBGQ100 10.0mH, 1.32mm Wire, DCR 0.39 Ohms 28.80 29.52


High Power   FBG Series,  1.25 mm wire,  CSA 1.23 sq mm,   Diam. 56mm, Ht 62mm,   Priced each
Order Code Spec. 10% 5%
  Type G Bobbin,  1.25mm Wire Tols 10% 5%
FBGT82 8.2mH, 1.25mm Wire, DCR 0.37 Ohms 26.40 27.06
FBGT91 9.1mH, 1.25mm Wire, DCR 0.39 Ohms 26.90 27.57
FBGT100 10.0mH, 1.25mm Wire, DCR 0.42 Ohms 27.44 28.13
FBGT110 11.0mH, 1.25mm Wire, DCR 0.44 Ohms 27.96 28.66
FBGT120 12.0mH, 1.25mm Wire, DCR 0.47 Ohms 28.48 29.19
FBGT130 13.0mH, 1.25mm Wire, DCR 0.49 Ohms 29.04 29.77
FBGT140 14.0mH, 1.25mm Wire, DCR 0.52 Ohms 29.56 30.30
FBGT150 15.0mH, 1.25mm Wire, DCR 0.54 Ohms 30.02 30.77

Air Core Bobbins

Air Cored Nylon Bobbins

Three sizes of coil bobbins made from Glass reinforced polyamide. These are suitable for the DIY constructor to wind custom inductors for their own loudspeaker crossovers and special projects. If you want help we can provide air cored Inductors wound to your own Inductance values. The wire diameters do however need to be selected from our available stocks. Some attention should be paid to the Inductance values that can be achieved with a particular bobbin size. Note that Air Core coils use approximately three times more copper wire than their Ferrite Core equivalent.
This increases the coil DCR significantly.
      Using 1.0mm copper wire the following inductance ranges can be achieved. If you increase the wire diameter then the available Inductance range will decrease as will the DCR.

Type 1 Bobbin (0.1 - 0.39)mH,
Type 2 Bobbin(0.1 - 0.91)mH,
Type 3 Bobbin 0.47 - 2.2)mH.

* Air Cored Bobbins. Price Each.
Order Code Spec. 1+ 6+ 11+
ACFRMS1 Air Core Bobbin Height 17mm. Diameter 40mm. 0.88 /ea 0.84 /ea 0.79 /ea
ACFRMS2 Air Core Bobbin Height 15mm. Diameter 47mm. 1.61 /ea 1.53 /ea 1.45 /ea
ACFRMS3 Air Core Bobbin Height 25mm. Diameter 58mm. 1.18 /ea 1.12 /ea 1.06 /ea

Air Core Inductors

Copper Wound Air Cored Crossover Inductors

Air cored crossover inductors wound on hard glass-reinforced Polyamide formers.
Type 1 Bobbin (0.1 to 0.39)mH, (17 * 40)mm,
Type 2 Bobbin (0.1 to 0.68)mH, (15 * 47)mm,
Type 3 Bobbin (0.47 to 2.2)mH, (25 * 58)mm.
Centre bolt hole with M4 Nylon bolt or fix with Silicone.
Tolerances +/- (10%, 5% or 2%).

* Air Cored Crossover Coils, Type 1 Bobbin, (17 * 40)mm. 10%, 5%, 2%. Price Each.
Order Code Spec. 10% 5% 2%
  Air Cored Inductors  Type 1 Bobbin.      
ACC110 0.10mH, 1.0mm Wire, DCR 0.12 Ohms 4.40 4.82 5.24
ACC115 0.15mH, 1.0mm Wire, DCR 0.16 Ohms 4.68 5.12 5.58
ACC122 0.22mH, 1.0mm Wire, DCR 0.20 Ohms 5.41 5.92 6.44
ACC133 0.33mH, 1.0mm Wire, DCR 0.25 Ohms 5.66 6.21 6.75
ACC139 0.39mH, 1.0mm Wire, DCR 0.29 Ohms 5.82 6.37 6.93


* Air Cored Coils, Type 2 Bobbin, (15 * 47)mm. 10%, 5%, 2%. Price Each.
Order Code Spec. 10% 5% 2%
  Air Cored Inductors  Type 2 Bobbin.      
ACC210 0.10mH, 1.0mm Wire, DCR 0.13 Ohms 5.06 5.49 5.93
ACC215 0.15mH, 1.0mm Wire, DCR 0.16 Ohms 5.36 5.78 6.24
ACC222 0.22mH, 1.0mm Wire, DCR 0.20 Ohms 5.68 6.12 6.61
ACC233 0.33mH, 1.0mm Wire, DCR 0.25 Ohms 5.99 6.47 6.98
ACC239 0.39mH, 1.0mm Wire, DCR 0.27 Ohms 6.32 6.82 7.36
ACC247 0.47mH, 1.0mm Wire, DCR 0.30 Ohms 6.73 7.27 7.86
ACC256 0.56mH, 1.0mm Wire, DCR 0.34 Ohms 7.08 7.65 8.25
ACC268 0.68mH, 1.0mm Wire, DCR 0.38 Ohms 7.51 8.10 8.73


* Air Core Crossover Coils, Type 3 Bobbin, (25 * 58)mm. 10%, 5%, 2%. Price Each.
Order Code Spec. 10% 5% 2%
Air Cored Inductors  Type 3 Bobbin.      
ACC347 0.47mH, 1.0mm Wire, DCR 0.30 Ohms 5.93 6.51 7.09
ACC356 0.56mH, 1.0mm Wire, DCR 0.34 Ohms 6.36 6.97 7.58
ACC368 0.68mH, 1.0mm Wire, DCR 0.38 Ohms 6.78 7.44 8.10
ACC375 0.75mH, 1.0mm Wire, DCR 0.41 Ohms 7.10 7.79 8.46
ACC382 0.82mH, 1.0mm Wire, DCR 0.45 Ohms 7.41 8.14 8.85
ACC391 0.91mH, 1.0mm Wire, DCR 0.49 Ohms 7.84 8.60 9.37
ACC310 1.00mH, 1.0mm Wire, DCR 0.51 Ohms 8.25 9.05 9.86
ACC312 1.20mH, 1.0mm Wire, DCR 0.60 Ohms 9.09 9.99 10.86
ACC315 1.50mH, 1.0mm Wire, DCR 0.64 Ohms 9.94 10.92 11.90
ACC318 1.80mH, 1.0mm Wire, DCR 0.71 Ohms 10.41 11.41 12.44
ACC322 2.20mH, 1.0mm Wire, DCR 0.81 Ohms 10.82 11.88 12.94

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