A 25.2

A-25.2 Music Hall A-25.2 Level 1 mod [$650 + frt retrofit, $990 + frt for new preinstalled machines]:

  • 2 sheets of SoundCoat chassis damping material cut & applied where applicable
  • 2 feet of DH Labs 23 awg Revelation series pure 99.999% silver solid core input signal wire with teflon tape-wrap dielectric
  • 1 pair of premium Vampire direct gold plated over copper body RCA female jacks
  • 4 Riken precision carbon film ½ watt signal resistors, 1%, with gold-plated leads
  • 2 Black-Gate C-Series electrolytic capacitors (signal coupling)
  • 2 Rel-Cap TFT teflon film and tin foil input coupling (to amp stage) bypass caps
  • 2 dual BurrBrown OPA-627 op amp modules (on DIP daughter boards). These are the world's best audio op amps!
  • 4 Vishay Telefunken ultra-fast soft recovery diodes
  • 4 EAR large sorbothane isolation feet
  • 10 feet WBT Solder used throughout
  • 4.5 hours labor
  • Our mini modification for the A-25.2 was designed by Chris Johnson, the founder and former president of Sonic Frontiers. It was designed to get as close to our Level-1 amp as possible at a lower selling price. It is covered by the Music Hall factory warranty.

The following details our mini modifications for the Music Hall A-25.2 integrated amplifier [$390 + frt retrofit, $790 + frt for new preinstalled machines]:

  • One pair of premium Vampire “direct gold plated over copper body” RCA female jacks to replace the cheap stamped nickel jacks of the stock unit.
  • 4 Riken precision Carbon Film ½ watt 1% signal path resistors,
  • 2 Black Gate C-Series electrolytic coupling capacitors
  • 2 Rel-Cap TFT Teflon Film and Tin Foil input coupling bypass caps for the amp stage.
  • 2 dual SMT-style Analog Devices OPA-8066 op amps (on DIP daughter boards).This is a substantial upgrade over the stock opamps.
  • 4 Vishay-Telefunken ultra-fast soft recovery diodes.
  • 1 sheet of Soundcoat chassis damping material cut and applied where applicable.
  • 2feet of DH Labs 23 gauge “Revelation series” pure 99.999% silver solid core input signal wire with Teflon tape-wrap dielectric.
  • 10 feet WBT Solder used throughout.
  • 3.5 hours labor.
  • Sonic improvements of the mini modification:
  • We improve the midrange and make the unit sound more liquid and warmer. This was a major design goal of the mod and we think that we have accomplished the task. The stock unit is good while the modified unit clearly better in the midrange.
  • Imaging is more focused while the soundstage is both deeper and wider.
  • The amp is quieter, silences are blacker to resolve more low-level detail, ambiance and three-dimensionality.
  • Transparency is dramatically improved. You get a cleaner look into the musical soundstage.
  • Dynamics are improved. Its like the amp gains more power. The stock unit is rated at 50 watts. The modified unit seems to play like a bigger amp.

Bass response is improved. Mid-bass slam is much improved.
Treble detail is improved and now keeps up with far more expensive amps.