Lundahl Transformers - Tube amplifier transformers

Tube amplifier transformers
MC and line input transformers, interstage and line output transformers, chokes and mains transformers.
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Tube amplifier output transformers have been moved to a separate page.

NOTE! All tube amplifier output transformers have been moved to a separate page.

Moving coil input transformers

Application Type Turns Ratio Size (LxWxH mm) Application examples

MC input LL1678 1+1+1+1 : 16+16 30x22.5x14.5 Moving coil input 1:8, 1:16 or 1:32 .
For low and medium impedance cartridges

MC input LL1681 1+1 : 13+13 48x29x20 Moving coil input 1:13 or 1:26 .
Mu-metal core. Internal Faraday shiled.
For low and medium impedance cartridges.

MC input LL1931 1+1 : 8+8 43x28x22 Prestigious moving coil transformer, 1:8 or 1:16.
Cardas Audio copper and Lundahl Amorphous strip core.
For medium and high impedance cartridges.

MC input LL1933 1+1 : 8+8 47x28x24 Prestigious moving coil transformer, 1:8 or 1:16.
Cardas Audio copper and classic Permalloy lamination core.
For medium and high impedance cartridges.

MC input LL1941 1+1 : 16+16 43x28x22 Prestigious moving coil transformer, 1:16 or 1:32.
Cardas Audio copper and Lundahl Amorphous strip core.
For low and medium impedance cartridges.

MC input LL1943 1+1 : 16+16 47x28x24 Prestigious moving coil transformer, 1:16 or 1:32.
Cardas Audio copper and classic Permalloy lamination core.
For low and medium impedance cartridges.

MC input LL9206 1+1+1+1 : 10+10 30x22.5x14.5 Moving coil input 1:5, 1:10 or 1:20.
For medium and high impedance cartridges.

MC input LL9226 1+1+1+1 : 10+10 30x22.5x14.5 Moving coil input 1:5, 1:10 or 1:20.
Improved version of LL9206
For medium and high impedance cartridges.

For MC transformer usage, please consult the following K&K Audio paper:
http://www.kandkaudio.com/mccartsetup.html

Application	Type	Turns Ratio	Size (LxWxH mm)	Application examples
MC input	LL1678	1+1+1+1 : 16+16	30x22.5x14.5	Moving coil input 1:8, 1:16 or 1:32 . For low and medium impedance cartridges
MC input	LL1681	1+1 : 13+13	48x29x20	Moving coil input 1:13 or 1:26 . Mu-metal core. Internal Faraday shiled. For low and medium impedance cartridges.
MC input	LL1931	1+1 : 8+8	43x28x22	Prestigious moving coil transformer, 1:8 or 1:16. Cardas Audio copper and Lundahl Amorphous strip core. For medium and high impedance cartridges.
MC input	LL1933	1+1 : 8+8	47x28x24	Prestigious moving coil transformer, 1:8 or 1:16. Cardas Audio copper and classic Permalloy lamination core. For medium and high impedance cartridges.
MC input	LL1941	1+1 : 16+16	43x28x22	Prestigious moving coil transformer, 1:16 or 1:32. Cardas Audio copper and Lundahl Amorphous strip core. For low and medium impedance cartridges.
MC input	LL1943	1+1 : 16+16	47x28x24	Prestigious moving coil transformer, 1:16 or 1:32. Cardas Audio copper and classic Permalloy lamination core. For low and medium impedance cartridges.
MC input	LL9206	1+1+1+1 : 10+10	30x22.5x14.5	Moving coil input 1:5, 1:10 or 1:20. For medium and high impedance cartridges.
MC input	LL9226	1+1+1+1 : 10+10	30x22.5x14.5	Moving coil input 1:5, 1:10 or 1:20. Improved version of LL9206 For medium and high impedance cartridges.

Transformers for input and DC-decoupled line output applications

Application Type Turns Ratio Size (LxWxH mm) Application examples

Line input/output LL1674 1+1 : 4+4 43x28x21 Amorphous core line input/output transformer

Line input/output LL1676 1+1 : 2+2 43x28x21 Amorphous core line input/output transformer

High level general purpose LL1684 1+1 : 1+1 42x28x22 For high level, low impedance applications such as (DC-decoupled) line output
The transformer is not suitable for line input from high impedance signal sources.

High level line input LL1690 1+1 : 1+1 42x28x22 For high level, high impedance applications such as (DC-free) line input.

Mic or line input LL7903 1+1+1+1 : 2+2+2+2 66x32x21 200 : 13 k ohms (used 1:8)
This is the ultimate microphone input transformer, designed for high quality tube equipment.

High stepup input LL7905 1+1+1+1 :
5.6 + 5.6 66x32x21 High level 600 ohms tube amplifier mic/line input (used 2 : 11.2)
Can also be used as a (DC-decoupled) line output transformer

Application	Type	Turns Ratio	Size (LxWxH mm)	Application examples
Line input/output	LL1674	1+1 : 4+4	43x28x21	Amorphous core line input/output transformer
Line input/output	LL1676	1+1 : 2+2	43x28x21	Amorphous core line input/output transformer
High level general purpose	LL1684	1+1 : 1+1	42x28x22	For high level, low impedance applications such as (DC-decoupled) line output The transformer is not suitable for line input from high impedance signal sources.
High level line input	LL1690	1+1 : 1+1	42x28x22	For high level, high impedance applications such as (DC-free) line input.
Mic or line input	LL7903	1+1+1+1 : 2+2+2+2	66x32x21	200 : 13 k ohms (used 1:8) This is the ultimate microphone input transformer, designed for high quality tube equipment.
High stepup input	LL7905	1+1+1+1 : 5.6 + 5.6	66x32x21	High level 600 ohms tube amplifier mic/line input (used 2 : 11.2) Can also be used as a (DC-decoupled) line output transformer

Type	Comment	Turns ratio	Primary inductance	Recommended DC current	Core Saturating DC current
LL1621/P-P	Noninverting interstage	1+1 : 1+1	300H	-	-
LL1621/6mA	Noninverting interstage / anode choke	1+1 : 1+1	130H	6 mA	10 mA
LL1635/P-P	Interstage	1+1 : 1+1	300H	-	-
LL1635/5mA	Interstage	1+1 : 1+1	130H	5 mA	9 mA
LL1635/20mA	Interstage	1+1 : 1+1	30H	20 mA	35 mA
LL1630/P-P	Line output	7.2+7.2 : 1+1	300 H	-	-
LL1630/5mA	Line output	7.2+7.2 : 1+1	130 H	5 mA	9 mA
LL1660	Interstage and line output	1+1+1+1 : 2.5+2.5	Application dependent	Application dependent	Application dependent
LL1660S	SE - PP and PP - PP Interstage Internal Faraday shields for improved balance	2.5+2.5 : 2 + 2	Application dependent	Application dependent	Application dependent
LL1667 and LL1668	Anode chokes	Dual coil 1+1	Application dependent	Application dependent	Application dependent
LL1671	High current interstage and line output	1+1+1+1 : 2+2	Application dependent	Application dependent	Application dependent
LL1677/80mA	High current interstage transformer (For 300B driving tube)	1+1+1+1 : 4+4	24H	80mA (1.2 Tesla saturation)	115mA
LL1680/5mA	Line output transformer Based on UTC LS-27 specifications	9+9 : 1+1+1+1	210H	5mA	10mA
LL1689	Line output transformer Based on the LL1660 size and structure	9+9 : 1+1+1+1	Application dependent	Application dependent	Application dependent
LL1692A	Interstage transformer Compromise between the LL1660 and the LL1671	1.75 + 1.75 : 1+1+1+1	Application dependent	Application dependent	Application dependent
LL2731	Low impedance line output transformer	1+1 : 1+1	Application dependent	Application dependent	Application dependent
LL1930	Mu metal core transformer for DC-free ("parafeed") line output	5.8 + 5.8 : 1+1	Not applicable	Not applicable	Not applicable

NOTE2! We recommend LL1630/5mA and LL1635/5mA for push-pull preamplifier stages where some DC imbalance occure. The LL1635 data sheet is updated to reflect some limitations in it's use.

NOTE3! For most SE applications, the LL1660 outperforms the LL1630 and LL1635

Mains transformers
In our C-core mains transformers, a very small air-gap is used to compensate for any DC unbalance in the mains outlet. Secondary voltages listed are no-load voltages. Voltage drop because of load is to be calculated from transformer copper resistance and load current.
Electrical size is estimated to 250VA, which can be increased with good cooling. For optimal use, about 75% of power should be taken from secondary 1. Primaries should be connected in series for 210 - 250 V, in parallel for 105 - 125V. Table entries are calculated for primary voltage 230 V.

Type Secondary 1 Secondary 2 and 3 Secondary 4 and 5 Secondary 6

LL1648 350V 5.9V 6.6V -

LL1649 230V 6.6V 6.6V -

LL1650 350V 6.6V 6.6V -

LL1651 500V 6.6V 6.6V -

LL1683 250V / 0.16A 6.6V / 3A 5.2V / 3A 48V / 0.1A

NOTE! Please study a very smart hybrid power supply principle. This principle avoids the very high voltage of an all tube rectifier and uses the transformer more efficiently.

Type	Secondary 1	Secondary 2 and 3	Secondary 4 and 5	Secondary 6
LL1648	350V	5.9V	6.6V	-
LL1649	230V	6.6V	6.6V	-
LL1650	350V	6.6V	6.6V	-
LL1651	500V	6.6V	6.6V	-
LL1683	250V / 0.16A	6.6V / 3A	5.2V / 3A	48V / 0.1A

Chokes for tube amp power supply

Type Inductance Rec. DC current Saturating current DC resistance

LL1638 / 4H 4 H 400mA 575 mA 36 ohms

LL1638 / 8H 8 H 200mA 290 mA 36 ohms

LL1638 / 10H 10 H 150 mA 215 mA 36 ohms

LL1673 / 10H 10 H 200 mA 290 mA 60 ohms

LL1673 / 15H 15 H 140 mA 200 mA 60 ohms

LL1673 / 20H 20 H 100 mA 145 mA 60 ohms

LL1685 / 100mA 17 H 100 mA 145 mA 130 ohms

LL1685 / 160mA 10 H 160 mA 230 mA 130 ohms

Type	Inductance	Rec. DC current	Saturating current	DC resistance
LL1638 / 4H	4 H	400mA	575 mA	36 ohms
LL1638 / 8H	8 H	200mA	290 mA	36 ohms
LL1638 / 10H	10 H	150 mA	215 mA	36 ohms
LL1673 / 10H	10 H	200 mA	290 mA	60 ohms
LL1673 / 15H	15 H	140 mA	200 mA	60 ohms
LL1673 / 20H	20 H	100 mA	145 mA	60 ohms
LL1685 / 100mA	17 H	100 mA	145 mA	130 ohms
LL1685 / 160mA	10 H	160 mA	230 mA	130 ohms

Filament current chokes

Type Inductance Rec. DC current Saturating current DC resistance

LL1694 / 1.5A 0.16H 1.5 A 2.2 A 2 ohms

LL1694 / 1.5A
(parallel) 40 mH 3 A 4.4 A 0.5 ohms

LL2733 / 1.7A 0.4H 1.7 A 2.7 A 3.4 ohms

LL2733 / 1.7A
(parallel) 0.1H 3.4 A 5.4 A 0.9 ohms

Type	Inductance	Rec. DC current	Saturating current	DC resistance
LL1694 / 1.5A	0.16H	1.5 A	2.2 A	2 ohms
LL1694 / 1.5A (parallel)	40 mH	3 A	4.4 A	0.5 ohms
LL2733 / 1.7A	0.4H	1.7 A	2.7 A	3.4 ohms
LL2733 / 1.7A (parallel)	0.1H	3.4 A	5.4 A	0.9 ohms

Per Lundahl,
Lundahl Transformers AB
Tibeliusgatan 7
SE-761 50 Norrtälje
SWEDEN
Phone: +46 - 176 139 30
Fax: +46 - 176 139 35
Email: