Mullard M8137 NOS tubes

I have a pair of these Mullard tubes installed in my phono stage (SOFTONE Model 4) replacing the stock tubes - SOVTEK 12AX7LPS. These NOS Mullard M8137 are also milliatry specs CV4004 (equivalent to 12AX7) and are much sought after for pre amp use.

Softone Model 4 phonostage

This is the Softone Model 4 phono stage, very well designed and made in Japan. It has ample gain for MC cartridges and muting function. It uses relays for switching inputs and MC cartridges are routed to a pair of step up transformers. Its stock tubes are a pair of Sovtek 12AX7LPS. I bought it used from a man from California and need a voltage step down transformer as it is 120V version, but its not a problem as the power consumption is a low 15W. The seller has already swapped the stock tubes with a pair of NOS Mullard M8137 (CV4004) which sounded excellent. The gain is a high 69dB and there is no noise and hum.

High quality inputs and components used throughout. Already a good value at the online price of USD650, I bought it for USD400.

Acoustic Signature Challenger turntable

Now, the main source is from this turntable which was bought used from a Singaporean. The TT is equipped with its own outboard power supply unit which outputs 12VAC (frequency adjustable) and preset at 2 speeds 45 & 33.3 rpm. It replaces the Linn LP12/Ittok LVII that has been around since 1980 and still performing well.

A Boston Audio Mat-1 solid graphite platter mat replaces the stock felt mat.

The tonearm is a unipivot Kuzma Stogi S bought from a friend in Penang. Cartridge options : Denon DL103R and Benz Micro 20E2L both moving coils. Phonostage is Japanese made Softone Model 4 which uses built-in step up transformers for MC inputs and 2 Sovtek 12AX7LPS tubes for amplification. The stock tubes have been replaced with NOS Mullard M8137s (CV4004). More on these later ....