Interstage, headphone and line output transformers
Our tube amplifier transformers are built in our dual coil single C-core style and can be ordered with a choice of core air-gap for Push-Pull or Single-Ended applications.
The use of C-cores with well-defined air-gap 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%.
Most of the transformers below are available with amorphous iron C-cores. The amorphous cores are considered to have sonic advantages, but the signal level capability with amorphous core is about 30% less than with a conventional silicon-iron C-core.
Interstage transformers
| Photo | Type | Turns ratio | Comment |
|---|---|---|---|
| LL1621 | 1+1 : 1+1 | Noninverting interstage / anode choke | |
 | LL1635 | 1+1 : 1+1 | Interstage. Preferably push pull to push pull. The LL1635 are an old designs and not well suited for SE applications. We recommend LL1635/5mA for push-pull preamplifier stages where some DC imbalance might occur. The LL1635 data sheet is updated to reflect some limitations in it's use. |
 | LL1660 | 1+1+1+1 : 2.5+2.5 | Interstage and line output. |
 | LL1660S | 2.5+2.5 : 2+2 | SE - PP and PP - PP Interstage. Internal Faraday shields for improved balance. |
 | LL1671 | 1+1+1+1 : 2+2 | High current interstage and line output. |
 | LL1677 | 1+1+1+1 : 4+4 | High current interstage transformer (For 300B driving tube). |
 | LL1692A | 1.75 + 1.75 : 1+1+1+1 | Interstage transformer. Compromise between the LL1660 and the LL1671. |
 | LL2746 | 1+1 : 2+2 | Stepup 1:2 interstage transformer, designed for two stage amplifiers. |
| LL2753 | 1+1 : 1+1 | For single end to single end applications. | |
| LL2756 | 1+1 : 1+1 | For single end to single end applications. High impedance version compared to LL2753. | |
 | LL2762 | 1+1 : 1+1 | Modified 1660 for SE to SE applications. |
Line output
| Photo | Type | Turns ratio | Comment |
|---|---|---|---|
 | LL1630 | 7.2+7.2 : 1+1 | Line output, primarily for push pull drive. The LL1630 are an old designs and not well suited for SE applications. We recommend LL1630/5mA for push-pull preamplifier stages where some DC imbalance might occur. |
 | LL1680 | 9+9 : 1+1+1+1 | Line output transformer Based on UTC LS-27 specifications |
 | LL1689 | 9+9 : 1+1+1+1 | Line output transformer Based on the LL1660 size and structure |
 | LL1930 | 5.8 + 5.8 : 1+1 | Mu metal core transformer for DC-free ("parafeed") line output |
 | LL2731 | 1+1 : 1+1 | Low impedance line output transformer |
 | LL2745 | 2.8+2.8 : 1+1+1+1 | Line output |
 | LL2747 | 2+2 : 1+1+1+1 | Small size low impedance line output transformer, normally used 1:1 |
 | LL2763 | 4+4 : 1+1+1+1 | Line output transformer based on the LL1660 size and structure. Available in copper or silver wire versions |
 | LL2793NC | 4+4 : 1+1+1+1 | Line output transformer with Nanocrystalline C-core, suitable for preamps, phono stages etcetera. |
