Moving coil input transformers

Application	Type	Turns Ratio	Size (LxWxH mm)	Application examples
MC input	LL9206	1+1+1+1 : 10+10	30x22.5x14.5	Moving coil input 1:5, 1:10 or 1:20. (No electrostatic shields)
MC input	LL1678	1+1+1+1 : 16+16	30x22.5x14.5	Moving coil input 1:8, 1:16 or 1:32 . (No electrostatic shields)
MC input	LL1681	1+1 : 13+13	48x29x20	Moving coil input 1:13 or 1:26 . Mu-metal core.
MC input	LL1931	1+1 : 8+8	43x28x22	Prestigious moving coil transformer . Cardas Audio copper and Lundahl Amorphous strip core.
MC input	LL1933	1+1 : 8+8	47x28x24	Prestigious moving coil transformer . Cardas Audio copper and classic Permalloy lamination core.
MC input	LL9226	1+1+1+1 : 10+10	30x22.5x14.5	Moving coil input 1:5, 1:10 or 1:20. Sonically improved LL9206

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

Transformers for input (and DC-free 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
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-free) line output transformer
High level general purpose	LL1684	1+1 : 1+1	42x28x22	For high level, low impedance applications such as (DC-free) line output The transformer is NOT suitable for line input unless the source is low impedance.
High level line input	LL1690	1+1 : 1+1	42x28x22	For high level, high impedance applications such as (DC-free) line input.

Anode chokes, interstage and line output transformers

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

NOTE1! All types above (except LL1930) can be gapped for other DC current than listed

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

Output transformers.
The LL1620, LL1623, LL1627 and LL9202 is a range of tube output transformers based on the same core size and winding topology. The range share the same high quality silicon iron C-core and have identical secondary windings. They differ only in the number of turns of the primary windings
Each type can be used for a number of different primary impedance levels by using different secondary terminations.
The transformers are available in push-pull or singel end versions with different core air-gap for different DC currents.
The transformers are highly sectioned (in all 10 sections) for excellent frequency response.

The use of C-cores and well defined airgaps results in an almost constant inductance throughout the whole operating voltage range. For SE transformers, the primary inductance variation due to signal level is less than 7%
The tables below displays only a few of many possible uses. Please refer to the full datasheets for more complete information.

Push-Pull. Voltage (RMS) and power @ 30 Hz

Type	Max Prim. Voltage	Inductance	Secondary* connection alt.	Prim. Z @ 8 ohms load	Loss, dB	Power
LL1627	380V	60H	C	1.2k	0.5	125W
LL1623	610V	150H	C	3.0k	0.5	125W
LL1620	860V	300H	C	6.0k	0.5	125W
LL9202	1180V	570H	C	11.0k	0.5	125W
LL1679 (w. UL)	670V	150H	C	4.5k	0.4	105W

Single-End. Voltage (RMS) and power @ 30 Hz

Type	Max Prim. Voltage	DC current	Inductance	Secondary* connection alt.	Prim. Z @ 8 ohms load	Loss, dB	Power
LL1627	170V	140mA	12H	C	1.2k	0.5	25W
LL1623	270V	90mA	30H	C	3.0k	0.5	25W
LL1620	380V	60mA	60H	C	6.0k	0.5	25W
LL1679 (w. UL)	295V	70mA	-	C	4.5k	0.4	20W
LL1620	525V	50mA	100H	C	11.0k	0.5	25W

"Secondary connection alt." refers to connection alternatives shown in the (pdf format) on line datasheet.

• Sometimes you need to more easily switch between different output impedances on our output transformers LL1620, LL1623 and LL1627. This sheet suggests two different wiring alternatives where the OPT secondary is reconnected using only three jumpers.
• The LL1620_CFB is a special version of the LL1620 where the primary windings have been split to allow for cathode feedback connections.
• The above transformers are now available with amorphous iron C-cores. We expect all application parameters to be similar for the amorphous core and the silicon iron cores, except that the amorphous cores signal handling capability is slightly smaller.
  From an engineering point of view, we can not justify the fairly high price of our amorphous core OPTs. But if in doubt of their merits,
  please read this enthusiastic report from at least one happy customer.

• The LL1663 is a 5k:8 ohms output transformer available in PP or SE versions


• The LL1664 is a 3k:8 ohms output transformer also available in PP or SE versions


• The LL1682 is a 5.5k:5 ohms output transformer also available in PP or SE versions
• The LL2735B is a 16k:8 ohms output transformer designed for high Rp tubes such as 10Y or 801A in SE applications

The LL1688 is a new, magnum size OPT primarily designed for the 845 tube. The LL1688 is presently (spring 2004) the biggest transformer in our OPT range.

LL1691
As it came out, the LL1688 is probably a little too sectioned for optimum performance. The LL1691 is less sectioned and has in some initial tests (spring 2005) performed even better than the LL1688. The LL1691 is however much less flexible than the LL1688.

The LL1691B
is a high impedance (20k : 8 ohm) version of the LL1691

The LL1693 is a supersized LL1627, introduced 2007.

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 / 0.16mA	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.

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