PLEASE READ BELOW VERY CAREFULLY !!! .... (Thank you :-))
These amps were bought brand new VTA180M Cherry Red Monoblock's using KT88 power tubes that I straight away had Bob Carver upgrade and re-spec using the uber-powerful KT-150 power tubes. He also modified the circuits to work with my Martin Logan "Spires" Electrostats, with an impedance of under 1 ohm @ 20KHz.
These amps are in effect better than his VTA305M amplifiers with 305W per channel in 8 ohms, 440W in 4 ohms, with the capability to work with less than 1 ohms loads. These amps are the pre-cursors to his Crimson RED 350 amps with less than 1-ohm load capability. The power specs of these amps are similar to the more powerful Crimson RED 350 amps, where both amps produce 440W and 400W in 4 and 2 ohms respectively.
In essence, with my Bob-Carver modified VTA-305M (+plus+), you are getting 87% of the power in 8 ohms and 100% of the power of the more powerful and expensive Crimson 350 RED amplifiers (~$10K) at a significant fraction of the cost.
Crimson REDs use KT120 tubes. My amp uses more powerful and more musical KT150 tubes.
These amps are individually hand-signed by Bob Carver himself (see pics)!
Specs are shown below. Bob Carver's measurements shown in BOLD
. The rest are the same as his stock VTA-305M monoblocs.
Number of Line Inputs: 1
Input impedance: 100 k ohms
Input Stage: 12AX7 current sourced long-tailed balanced pair
Pre-driver Stage: 12AT7 current sourced long-tailed balanced pair
Automatic DC Restoration: 6AL5
Nominal Voltage Gain: 30 dB (into 8 ohms)
Output Stage Configuration: 3 complimentary Sets of KT150s in a push-pull configuration (6 total)
Regulated Screen Supply Voltage: 390V
Output tube plate voltage: 785V
Output tube Idle Power: 9.8W (stock VTA-305 is 14W)
Bias Adjustment: Rear panel pot, front panel meter, set and forget...Bob Carver recommends a 70mA bias setting.
Bob Carver's Custom Power Specs:
- 305 watts into 8 ohms (Cherry RED VTA350M spec'd slightly higher @ 350W into 8 ohms. Same as stock VTA305M)
- 438 watts into 6 ohms (no spec given for stock VTA305M)
- 440 watts into 4 ohms (Same as more powerful Cherry RED VTA350M!. A stock VTA305M was rated @330 watts into 4 ohms).
- 400 watts into 2 ohms (Same as more powerful Cherry RED VTA350M!. A stock VTA305M was rated @290 watts into 2 ohms).
- 350 watts into 1 ohm (stock VTA305M not rated for 1-ohm operation).
Noise: > 123 dB A-Weighted referenced into 305W watts ... Bob carver says "better than solid-state". I can confirm that these amps are dead silent and this number is better than the best and quietest DACs out there...almost 21-bit performance. Full HD/Ultra-HD audio performance!
Frequency Response: 2 Hz to 180 kHz!!! (More than doubled frequency response @1W !!! ... stock VTA305M spec'd at 2 Hz to 85 kHz)
Full Power Bandwidth: 22Hz to 46KHz (Extended full power response by almost 20kHz !!!...stock VTA305M spec'd at 24 Hz to 28 kHz)
Feedback Control Switch: 20dB for Vintage Amplifier Sound, 11 dB for Contemporary Amplifier Sound
Distortion: Less than 0.5% (... 0.32% for these modified amps at rated power. Though it's an order of magnitude less (10X or more) at normal listening volumes)
Output Impedance: 0.5 ohms (...stock VTA305M spec'd at 1.3 ohms)
Output Transformer: Interleaved windings, super wideband low leakage inductance design
Bob Carver says of this custom design "This amp is going to sound stunning!", "There is no doubt in my mind that they will sound stunning!", and after the mods were finished ... "Listening tests confirm we are in the presence of greatness!" ... and I heartily concur !!!
Many positive reviews of the VTA180M or VTA305M abound online.
I personally recommend a 72-96 hour tube burning before serious listening tests are done since tubes have been dormant for almost 4 years in a temperature-controlled storage room.
Speaker outputs 2, 4, and 8-ohm terminals ... but use the 8-ohm terminal only per Bob Carver's recommendation for maximum power.
Built-in Output Tube tester: Yes
Construction Method: Point-to-Point hand-wired axial and radial leaded components with star grounds and no circuit board traces or de-pluggable connectors.
Components: High-reliability wire wound and metal film resistors, Metal polyester capacitors in the audio signal paths.
2 HEAVY GAUGE CUSTOM "Victor Lemonte Wooten" ('Fun and Classy Purple Signature MusicCord PRO') power cords from ESP included.
6.6ft (2m) long ... a free $500 value!!!!!
Soft PDF Manual for the VTA-305M can be provided. It is also available online.
Weight: 45 pounds (per box) x2 boxes
Dimensions (WHD): 17″ x 14" x 22"
Color: Glossy Cherry
Country of Origin: United States of America