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.




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Interstage transformers

PhotoTypeTurns ratioComment
LL16211+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+2SE - 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+2Stepup 1:2 interstage transformer, designed for two stage amplifiers.
LL2753 1+1 : 1+1For single end to single end applications.
LL2756 1+1 : 1+1For single end to single end applications. High impedance version compared to LL2753.
LL2762 1+1 : 1+1Modified 1660 for SE to SE applications.
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Line output

PhotoTypeTurns ratio Comment
LL16307.2+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.
LL16809+9 : 1+1+1+1 Line output transformer Based on UTC LS-27 specifications
LL16899+9 : 1+1+1+1 Line output transformer Based on the LL1660 size and structure
LL19305.8 + 5.8 : 1+1 Mu metal core transformer for DC-free ("parafeed") line output
LL2731 1+1 : 1+1 Low impedance line output transformer
LL27452.8+2.8 : 1+1+1+1 Line output
LL2747
2+2 : 1+1+1+1Small size low impedance line output transformer, normally used 1:1
LL27634+4 : 1+1+1+1Line output transformer based on the LL1660 size and structure. Available in copper or silver wire versions
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Headphone output transformers

PhotoTypeTurns ratioComment
LL2754 1+1 : 1+1 For low impedance sources
LL27656+6 : 1+1Primary impedance approx. 5k with 32, 150 or 600 ohm headphones
LL27746.8+6.8 : 1+1+1+1For 3k primary impedance to 16, 64 and 300 ohms
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