McCormack Power Drive DNA-1

Cleburne, TX 76033, USA

2 hours ago

This is a steal for this amp, so price is firm. McCormack Power Drive Dna-1, In excellent condition total re-store on this amp no corners were cut this amp will drive any speaker and never break a sweat. Very warm sounding solid state amp. If interested, please give me a call. This is a report of all work performed to this Amp. McCormack DNA1 Deluxe upgrade report The scope of the upgrade and restoration work performed on this amplifier is outlined below,  Repaired damaged ground bus connections in the voltage regulator circuit.  Repaired one damaged trace in the audio amplifier circuit  Performed the C-mod, eliminating the DC servo circuitry, setting DC gain to zero and installing a potentiometer in each channel to manually adjust DC offset. Added additional low voltage regulation stages prior to the manual potentiometers to further reduce noise.  Crosstalk mod performed, modifying the power supply circuit paths to bring down inter-channel cross talk by nearly -10dB over the stock DNA-1.  Adjusted amplifier gain down from -32dB to -27dB to allow for better pairing with preamps of typical gain levels.  Replacement of all electrolytic capacitors on the main driver board. Nichicon audio grade capacitors used in critical locations.  Replacement of polystyrene DC rail decoupling capacitors with high grade Wima Polypropylene capacitors in a higher capacitance value to extend bypass benefits.  Installed AC snubbers on the channel boards  Installed an isolated chassis ground bus bar and a safety ground break device to eliminate ground loops.  Rebuilt the circuit ground to isolate it from chassis ground and rewired the full amplifier grounding system to create a central star ground, yielding large improvements in residual noise, SNR and aiding amplifier stability.  Replacement of 16 main power supply capacitors (8 per side) on the channel boards with high grade capacitors. Upgraded to 6,800uF capacitors from the original 4,700uF caps.  Removed original polystyrene bypass film bypass caps on the channel boards to improve amplifier stability.  Installed new mica insulators and thermal compound to replace the original Silpad insulators.  Installed upgraded RCA and high grade binding posts.  Installed new shielded Cardas signal wiring for the L & R input.  To improve reliability all IC’s were removed from the circuit board. The solder pads were then cleaned and tinned and the IC’s then reinstalled ensuring solid solder connections to the freshly prepped solder pads.  Added additional ground buss to both channels to eliminate future through-hole connectivity issues.  All soldering work performed with Cardas Quad Eutectic silver solder.  Setup output stage bias and checks for DC offset, square wave testing, etc. Thanks Phillip