IT Spulen

Coils

Coils are often categorised in air core coils and core coils. Air core coils usually don't have a core (they might have a synthetic core without electromagnetic properties). Core coils have a core made of ferromagnetic material (ferrite, iron sheet etc.) to increase its inductance.

Air core coils are best since they don't show any loss due to reverse flux. They often have the disadvantage of being too large at a given inductance and DC resistance. In this case, a ferromagnetic core has to be added to reduce the size.

The reverse flux loss in core coils

Cores made of ferromagnetic materials to increase coil inductance show two types of loss:
- hysteresis loss, since the core material (with elementary magnets) aligns itself slowly and
- Eddy-current loss due to the conductivity of the material.
Both loss types result in sound degradation and not applicable to air core coils.

DC Loss

The wire used for the coil possesses a DC resistance. Reducing the DC resistance by employing a coil in series to a bass driver, results in tighter and cleaner bass. The DC resistance doesn't cause any harmonic distortion and, therefore, sound degradation.

Microphonics Effect

Besides the reverse flux loss, the microphonics effect also plays a role in all types of coils.

The microphonics effect (interaction of current flowing through the coil -> magnetic field -> -> mechanical movement of coil wires -> and the resulting induced voltage in the coil) adds information to the original signal. Details of the original signal are overlaid and alienated; the music lacks three-dimensionality and transparency. To avoid this, the wires should be more secured in place. This can be done by
a) manufacturing the coil with baked varnish wires and where the entire coil is then baked too,
b) impregnating the coil in a vacuum with special varnish down to the innermost wires and is then baked
c) using a foil coil.

The table below shows which coil works best for a specific driver type.

Coil type (partly with brand names)	Size	DC- resistance	Power handling	Application	Core material / properties
air core coil 0.7mm or backed varnish air core coil 0.7mm	relatively small	high	low	in parallel to tweeters or in correction circuits	air / without reverse flux loss
air core coil 1.0mm or backed varnish air core coil 1.0mm	medium	medium	medium	in parallel to powerful tweeters in series to midrange and small bass drivers	air / without reverse flux loss
air core coil 1.4mm or backed varnish air core coil 1.4mm	large	medium to small	medium to high	in series to midrange and bass drivers	air / without reverse flux loss
air core coil 2.0mm or larger ....	very large	low	high	in series to bass drivers	air / without reverse flux loss
air core coils made of copper, silver or silver/gold foil Tritec air core coils	large	medium to small	medium to high	in series to midrange and bass drivers for state-of-the-art speakers	air / without reverse flux loss
H71 and H100 core coil, affordable ferrite core coils	medium to small	medium	medium	everywhere, where an air core coil would be too large or too pricey	ferrite / with reverse flux loss
H140 core coils , I core coils	medium	low	high to very high	in series to bass drivers for speakers with high power handling	ferrite / with reverse flux loss
transformer core coils,	Zero Ohm Coils	medium	low	high to very high	in series to bass drivers for speakers with high power handling	ferrite / with reverse flux loss

Please not: the coil's polarity is of no importance! Mundorf

Preferred coil types

All above coils are made from copper varnished wire with a purity of > 99,99%. The bobbin is made of synthetic material. The wire ends are tin-plated and marked. The inductance is measured at 25 degrees Celsius, tolerance is +/- 5%. L denotes inductance, R is the DC resistance, D the diameter and H the height. All prices include German VAT.

Please note: the values for Pmax were determined at 25 degrees Celsius ambient temperature at 50 Hz and with free convection. These are just ballpark figures! Since we are not the manufacturer we cannot guarantee the coils' measurement results.

All coils supplied by us are made by Mundorf, Intertechnik and Monacor.

Air core coils,
Type L71

absolutely low distortion
air core coil with 0.71 mm wire Mundorf Luftspule 0,7mm

Baked Varnish Air Coils
and other values
at our Mundorf page

Air Coils L71 (wire with 0.71 mm diameter)

Product ID	L/mH	R/Ohm	Wire- D/mm	Pmax*) 8Ohm	Coil Size (DxH/mm)	Price
M-L71-005	0.050	0.19	0.71	35 W	25 x 10	EUR 3,15
M-L71-010	0.10	0.23	0.71	31 W	25 x 10	EUR 3,15
M-L71-012	0.12	0.25	0.71	42 W	36 x 10	EUR 3,22
M-L71-015	0.15	0.28	0.71	39 W	36 x 10	EUR 3,25
M-L71-018	0.18	0.31	0.71	38 W	36 x 10	EUR 3,35
M-L71-022	0.22	0.34	0.71	37 W	36 x 10	EUR 3,45
M-L71-027	0.27	0.39	0.71	34 W	36 x 10	EUR 3,55
M-L71-033	0.33	0.43	0.71	33 W	36 x 10	EUR 3,65
M-L71-039	0.39	0.51	0.71	29 W	36 x 10	EUR 3,75
M-L71-047	0.47	0.58	0.71	21 W	30 x 20	EUR 3,85
M-L71-056	0.56	0.64	0.71	20 W	30 x 20	EUR 3,95
M-L71-068	0.68	0.71	0.71	20 W	30 x 20	EUR 4,15
M-L71-082	0.82	0.81	0.71	18 W	30 x 20	EUR 4,35
M-L71-100	1.0	0.91	0.71	17 W	30 x 20	EUR 4,54
M-L71-120	1.2	1.0	0.71	18 W	40 x 20	EUR 4,65
M-L71-150	1.5	1.1	0.71	17 W	40 x 20	EUR 4,95
M-L71-180	1.8	1.2	0.71	17 W	40 x 20	EUR 5,25
M-L71-220	2.2	1.4	0.71	16 W	40 x 20	EUR 5,85
M-L71-270	2.7	1.5	0.71	15 W	40 x 20	EUR 6,15
M-L71-330	3.3	1.8	0.71	14 W	40 x 20	EUR 6,75
M-L71-390	3.9	2.0	0.71	16 W	58 x 18	EUR 7,15
M-L71-470	4.7	2.2	0.71	16 W	58 x 18	EUR 7,65
M-L71-560	5.6	2.4	0.71	16 W	58 x 18	EUR 8,15
M-L71-680	6.8	2.7	0.71	15 W	58 x 18	EUR 8,85
M-L71-820	8.2	3.1	0.71	14 W	58 x 28	EUR 9,85
M-L71-1000	10.0	3.6	0.71	13 W	58 x 28	EUR 10,70

*) Pmax 8 Ohm is the maximum power that this coil is able to deliver to the bass driver. The values are valid for free air convection and 20°C. For 4 Ohm speakers this value has to be halved.

Air core coils,
Type L100

absolutely low distortion
air core coil with 1.0 mm wire Mundorf Luftspule 0,7mm

Baked Varnish Air Coils
and other values
at our Mundorf page

Air Coils L100 (wire with 1.0 mm diameter)

Product ID	L/mH	R/Ohm	Wire- D/mm	Pmax*) 8Ohm	Coil Size (DxH/mm)	Price
M-L100-010	0.10	0.14	1.00	82 W	30 x 20	EUR 3,75
M-L100-012	0.12	0.15	1.00	82 W	30 x 20	EUR 3,85
M-L100-015	0.15	0.17	1.00	77 W	30 x 20	EUR 3,95
M-L100-018	0.18	0.19	1.00	73 W	30 x 20	EUR 4,15
M-L100-022	0.22	0.21	1.00	70 W	30 x 20	EUR 4,35
M-L100-027	0.27	0.23	1.00	68 W	30 x 20	EUR 4,54
M-L100-033	0.33	0.26	1.00	77 W	40 x 20	EUR 4,65
M-L100-039	0.39	0.29	1.00	71 W	40 x 20	EUR 4,85
M-L100-047	0.47	0.32	1.00	67 W	40 x 20	EUR 5,05
M-L100-056	0.56	0.36	1.00	62 W	40 x 20	EUR 5,25
M-L100-068	0.68	0.39	1.00	60 W	40 x 20	EUR 5,55
M-L100-082	0.82	0.44	1.00	56 W	40 x 20	EUR 5,85
M-L100-100	1.0	0.49	1.00	61 W	58 x 18	EUR 6,35
M-L100-120	1.2	0.54	1.00	63 W	58 x 18	EUR 6,85
M-L100-150	1.5	0.62	1.00	60 W	58 x 18	EUR 7,35
M-L100-180	1.8	0.70	1.00	58 W	58 x 18	EUR 7,85
M-L100-220	2.2	0.83	1.00	53 W	58 x 22	EUR 8,85
M-L100-270	2.7	0.90	1.00	46 W	58 x 28	EUR 9,35
M-L100-330	3.3	1.1	1.00	44 W	58 x 28	EUR 10,70
M-L100-390	3.9	1.1	1.00	43 W	58 x 28	EUR 11,70
M-L100-470	4.7	1.3	1.00	46 W	70 x 29	EUR 12,70
M-L100-560	5.6	1.4	1.00	44 W	70 x 29	EUR 13,70
M-L100-680	6.8	1.6	1.00	42 W	70 x 29	EUR 15,60
M-L100-820	8.2	1.7	1.00	39 W	70 x 29	EUR 17,60
M-L100-1000	10.0	1.9	1.00	36 W	70 x 29	EUR 19,60

*) Pmax 8 Ohm is the maximum power that this coil is able to deliver to the bass driver. The values are valid for free air convection and 20°C. For 4 Ohm speakers this value has to be halved.

Air core coils,
Type L140

absolutely low distortion
air core coil with 1.4 mm wire Mundorf Luftspule

Baked Varnish Air Coils
and other values
at our Mundorf page

Air Coils L140 (wire with 1.4 mm diameter)

Product ID	L/mH	R/Ohm	Wire- D/mm	Pmax*) 8Ohm	Coil Size (DxH/mm)	Price
M-L140-010	0.10	0.07	1.4	267 W	40 x 20	EUR 4,85
M-L140-012	0.12	0.08	1.4	265 W	40 x 20	EUR 5,35
M-L140-015	0.15	0.10	1.4	237 W	40 x 20	EUR 5,85
M-L140-018	0.18	0.11	1.4	251 W	58 x 18	EUR 6,35
M-L140-022	0.22	0.12	1.4	248 W	58 x 18	EUR 6,85
M-L140-027	0.27	0.13	1.4	245 W	58 x 18	EUR 7,35
M-L140-033	0.33	0.15	1.4	227 W	58 x 18	EUR 7,85
M-L140-039	0.39	0.16	1.4	239 W	58 x 18	EUR 8,35
M-L140-047	0.47	0.19	1.4	213 W	58 x 18	EUR 8,85
M-L140-056	0.56	0.20	1.4	192 W	58 x 22	EUR 9,35
M-L140-068	0.68	0.23	1.4	197 W	58 x 28	EUR 9,85
M-L140-082	0.82	0.26	1.4	184 W	58 x 28	EUR 10,70
M-L140-100	1.0	0.30	1.4	168 W	58 x 28	EUR 11,70
M-L140-120	1.2	0.34	1.4	164 W	70 x 29	EUR 12,70
M-L140-150	1.5	0.38	1.4	156 W	70 x 29	EUR 13,70
M-L140-180	1.8	0.43	1.4	146 W	70 x 29	EUR 14,70
M-L140-220	2.2	0.46	1.4	152 W	70 x 29	EUR 16,60
M-L140-270	2.7	0.51	1.4	133 W	77 x 28	EUR 17,60
M-L140-330	3.3	0.58	1.4	131 W	77 x 28	EUR 19,60
M-L140-390	3.9	0.65	1.4	123 W	77 x 28	EUR 21,65
M-L140-470	4.7	0.80	1.4	103 W	70 x 59	EUR 24,65
M-L140-560	5.6	0.89	1.4	98 W	70 x 59	EUR 27,55
M-L140-680	6.8	1.1	1.4	86 W	70 x 59	EUR 30,55
M-L140-820	8.2	1.1	1.4	89 W	70 x 59	EUR 33,55
M-L140-1000	10.0	1.2	1.4	94 W	88x75x61	EUR 37,45

*) Pmax 8 Ohm is the maximum power that this coil is able to deliver to the bass driver. The values are valid for free air convection and 20°C. For 4 Ohm speakers this value has to be halved.

Drum-core coils (H coils) with ferrite

The design of this coil type is similar to the air core coil, except that it contains a ferrite core. The vertical bar is resting partly inside the coil while the horizontal bar is covering the labelled side. The magnetisation curve is linear at small to medium volumes, meaning that distortion is low.

Ferrite Coils

Mundorf H Core Coil H100 (wire with 1.0 mm diameter)

Product ID	L/mH	R/Ohm	Wire- D/mm	Pmax^*) 8Ohm	Coil Size (DxH/mm)	Price
M-h100-068	0.68	0.11	1.00	177	40 x 38	EUR 6,35
M-h100-082	0.82	0.12	1.00	167	40 x 38	EUR 6,35
M-h100-100	1.0	0.13	1.00	159	40 x 38	EUR 6,35
M-h100-120	1.2	0.15	1.00	142	40 x 38	EUR 8,35
M-h100-150	1.5	0.17	1.00	129	40 x 38	EUR 8,65
M-h100-180	1.8	0.19	1.00	118	40 x 38	EUR 8,95
M-h100-200	2.0	0.20	1.00	115	40 x 38	EUR 10,30
M-h100-220	2.2	0.21	1.00	111	40 x 38	EUR 10,70
M-h100-270	2.7	0.24	1.00	100	40 x 38	EUR 11,30
M-h100-300	3.0	0.25	1.00	99	40 x 38	EUR 11,70
M-h100-330	3.3	0.27	1.00	93	40 x 38	EUR 12,30
M-h100-390	3.9	0.30	1.00	88	40 x 38	EUR 12,70
M-h100-470	4.7	0.34	1.00	82	40 x 38	EUR 13,30
M-h100-560	5.6	0.39	1.00	74	40 x 38	EUR 13,70
M-h100-680	6.8	0.46	1.00	64	40 x 38	EUR 14,30
M-h100-820	8.2	0.54	1.00	57	40 x 38	EUR 14,70
M-h100-1000	10.0	0.64	1.00	58	56 x 35	EUR 17,60
M-h100-1200	12.0	0.71	1.00	59	56 x 35	EUR 18,60
M-h100-1500	15.0	0.83	1.00	53	56 x 35	EUR 19,60
M-h71-1800	18.0	1.3	0.71	21	40 x 38	EUR 12,30
M-h71-2200	22.0	1.5	0.71	18	40 x 38	EUR 12,70
M-h71-2700	27.0	1.7	0.71	17	40 x 38	EUR 13,30
M-h71-3300	33.0	1.9	0.71	15	40 x 38	EUR 13,70

*) Pmax 8 Ohm is the maximum power that this coil is able to deliver to the bass driver. The values are valid for free air convection and 20°C. For 4 Ohm speakers this value has to be halved.

More H core coils (H71, H100, H140, BH71, BH100 and BH140) are on the H core page.

i-Punkt© coils

A coil with extreme power handling, consisting of granular aligned silicon sheet iron with high saturation current.

Product ID	L/mH	R/Ohm	wire D/mm	Pmax 8Ohm	dimensions (LexW/mm)	Price
I-1000	1.2	0.13	1.32	500 W	130 x 46	EUR 22,75
I-1001	1.5	0.14	1.32	500 W	130 x 46	EUR 22,45
I-1002	1.8	0.16	1.32	490 W	130 x 46	EUR 23,75
I-1003	2.2	0.17	1.32	480 W	130 x 46	EUR 23,65
I-1004	2.7	0.19	1.32	430 W	130 x 46	EUR 23,95
I-1005	3.3	0.21	1.32	380 W	130 x 46	EUR 24,45
I-1006	3.9	0.24	1.32	340 W	130 x 46	EUR 24,85
I-1007	4.7	0.26	1.32	310 W	130 x 46	EUR 25,65
I-1008	5.6	0.29	1.32	280 W	130 x 46	EUR 26,15
I-1013	6.8	0.44	1.12	200 W	130 x 46	EUR 24,65
I-1014	8.2	0.49	1.12	180 W	130 x 46	EUR 25,65
I-1015	10	0.56	1.12	150 W	130 x 46	EUR 26,55

*) Pmax 8 Ohm is the maximum power that this coil is able to deliver to the bass driver (at 4 Ohm this value has be halved).

smaller i-Punkt© coils or different values upon request or as per IT catalogue

reasonably priced ferrite core coils

Reasonably priced coils, especially suited for equalisation circuits.

Up to 5.6 mH all coils contain a HQ soft ferrite, tube-shaped core. From 6.8 mH upwards the coils contain a cylindrical core (without picture).

Product ID	L/mH	R/Ohm	wire D/mm	dimensions (DxH/mm)	Price
I-0249	0.82	0.48	0.71	32 x 26	EUR 3,09
I-0250	1.00	0.53	0.71	32 x 26	EUR 3,29
I-0251	1.20	0.61	0.71	32 x 26	EUR 3,49
I-0252	1.50	0.69	0.71	32 x 26	EUR 3,69
I-0254	1.80	0.80	0.71	32 x 26	- not available
I-0256	2.00	0.84	0.71	32 x 26	EUR 4,09
I-0960	2.20	1.09	0.60	32 x 26	EUR 2,89
I-0962	2.70	1.23	0.60	32 x 26	EUR 3,19
I-0964	3.30	1.41	0.60	32 x 26	- not available
I-0966	3.90	1.58	0.60	32 x 26	EUR 3,39
I-0968	4.70	2.31	0.50	32 x 26	EUR 3,19
I-0970	5.60	2.56	0.50	32 x 26	EUR 3,29
I-0972	6.80	2.02	0.60	44 x 36	EUR 7,59
I-0974	8.20	2.27	0.60	44 x 36	EUR 7,79
I-0976	10.0	3.48	0.50	44 x 36	EUR 7,49
I-0978	12.0	3.87	0.50	44 x 36	EUR 7,89
I-0980	15.0	4.40	0.50	44 x 36	EUR 8,09
I-0982	18.0	3.74	0.60	55 x 36	EUR 9,29
I-0984	22.0	4.26	0.60	55 x 36	EUR 9,89
I-0986	27.0	4.89	0.60	55 x 36	EUR 10,30

Transformer core coils

for high power application in either circular (TO1000) or Intertechnik Torobarspule

square version (FE96 andFE130). Intertechnik Trafospule

Product ID Type	L/mH	R/Ohm	wire D/mm	Pmax 8Ohm	dimensions (DxH/mm)	Price
TO1000
I-592	10	0.27	-	250 W	87 x 41	EUR 47,90
FE 96
I-370	3.9	0.16	1.8	650 W	96x86x88	EUR 65,60
FE 130
I-750	6.8	0.12	2.5	1300 W	130x98x116	EUR 154,00
I-790	15	0.28	2.0	600 W	130x98x116	EUR 109,00
I-800	18	0.33	2.0	550 W	130x98x116	EUR 115,00
I-810	22	0.37	2.0	500 W	130x98x116	EUR 119,00

*) Pmax 8 Ohm is the maximum power that this coil is able to deliver to the bass driver (at 4 Ohm this value has be halved).

other values: Mundorf Feron transformer core coils

PA transformer core coils

Monacor transformer core coil with high power handling. The coil has OFC wire turns and is vacuum impregnated. PA-Spule

These characteristics are available at an amazingly low price.

This coil is also suited for subwoofers and bass drivers in hi-fi loudspeakers.

Product ID Type	L/mH	R/Ohm	wire D/mm	Pmax 8Ohm	dimensions (DxH/mm)	Price
mo-125410	2.2	0.10	1.2	500 W	6050x42	EUR 18,00
mo-125420	2.7	0.12	1.2	500 W	60x50x42	EUR 18,80
mo-125430	3.3	0.13	1.2	500 W	60x50x42	EUR 19,20
mo-125440	3.9	0.16	1.2	500 W	60x50x42	EUR 19,70
mo-125450	4.7	0.14	1.4	500 W	68x58x55	EUR 25,80
mo-125460	5.6	0.15	1.4	480 W	68x58x55	EUR 26,60
mo-125470	6.8	0.16	1.4	480 W	68x58x55	EUR 27,70
mo-125480	8.2	0.17	1.4	370 W	68x58x55	EUR 28,70
mo-125490	10	0.19	1.4	330 W	68x58x55	EUR 30,00
mo-123190	12	0.14	1.6	480 W	76x65x92	EUR 63,10
mo-123200	15	0.12	1.8	1000 W	96x82x102	EUR 87,80

*) Pmax 8 Ohm is the maximum power that this coil is able to deliver to the bass driver (at 4 Ohm this value has be halved).

to other coils:

Mundorf large Mundorf air core coils.

Mundorf CFC coils (copper foil capacitor)
with excellent three-dimensionality and attention to detail; they belong to the group of exceptionally neutral capacitors.

Mundorf Aronit core coils

Mundorf Feron i core coils

Mundorf Feron transformer core coils

Mundorf Zero Ohm Coils

Further coils upon request

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