McIntosh MC225 Vintage Tube Amp, ABKCO Music THE ROLLING STONES & MORE
Friday, August 30th, 2024
McIntosh MC225 Vintage Tube Amp, ABKCO Music – THE ROLLING STONES & MORE! General: This is no ordinary MC225 vintage McIntosh tube amplifier. This MC225 comes to you from ABKCO Music & Records, home to The Rolling Stones, Chubby Checker, Sam Cooke, and many more! Check out our photos to see ABKCO owner & founder Mr. Allen Klein alongside the BEATLES, with McIntosh gear prominently featured in his office and recording studios. Born in Newark, NJ, Mr. Klein was an American businessman whose aggressive negotiation tactics fundamentlly changed industry standards for compensating recording artists. Klein also increased profits for his musician clients by negotiating new record company contracts. He first scored monetary and contractual gains for Buddy Knox and Jimmy Bowen, one-hit rockabillies of the late 1950′s, then parlayed his early successes into a position managing Sam Cooke. He went on to manage The Beatles and the Rolling Stones simultaneously!!! , along with many other artists, becoming one of the most powerful individuals in the music industry during his era. (Above three paragraphs courtesy of Wikipedia with some editing) Many audiophiles hail the McIntosh MC225 as the best sounding vintage tube amp from McIntosh ever. Especially if you have high efficiency speakers. We totally agree that if you don’t need the extra 40W or 50W from the MC240 or MC275, then this is your best choice. However, don’t be fooled into thinking an unrestored eBey special will perform to that level. This gorgeous MC225 was just serviced this year with extra care being given to maintaining the original signature sound while making it more reliable and safer to use. SkyFi Service Notes: – This amplifier was serviced by Analogique in 1992 and by Bristol Electronics in 2023. The power supply has misc. The core circuit remains almost completely original. SkyFi Cosmetic Notes: – Lettering shows wear. Chrome has light pitting. Tops of transformers have light scratching. Bottom cover is scratched on bottom only. SkyFi Tube Notes: – When this amplifier came in it had a very tired set of coin base 7591 tubes installed and the amp could not reach its rated power of 25WPC. We swapped out the outputs for a matched quad of current production Russian Tung Sol reissues. The remaining driver tubes were replaced with misc. Strong vintage tubes selected from our stock. National 12AX7, RFT (East Germany) 12AU7, and GE 12BH7. With the fresh set of tubes this amplifier is singing again and meeting 25WPC with ease. This listing includes the MC225 amplifier, and the repair receipt. More from the MC225 Owner’s Manual: The MC225 has on one chassis two 25 watt power amplifiers. In addition to use as a stereo amplifier, the flexibility of the MC225 permits it to be uséd as a monophonic amplifier that delivers 50 watts, or as two separate 25 watt amplifiers with each channel amplifying completely separate pro- grams, or as two amplifiers for use with an electronic crossover network. Such flexibility permits maximum use for greatest return from your investment. Over one million watts of amplifier output power capacity have been manufactured by Mclntosh since 1947. In this 1,000,000 watts of audio power there are less than 10 watts of distortion capacity and less than 1/100 watt of noise capacity! The dramatic difference in the quality of music reproduction when you listen through Mclntosh instruments is directly due to low distortion performance. Careful, devoted research is a way of life at Mclntosh. The world’s finest amplifier is the creation of per- severing, resourceful Mclntosh engineers. Patent Office has recognized the advanced technology of the Mclntosh circuit by granting 6 patents. More on ABKCO Music & Records: ABKCO Music & Records is one of the world’s leading independent entertainment companies. It is home to iconic music catalogs that include compositions and recordings by Sam Cooke, The Rolling Stones, Bobby Womack, Eric Burdon, The Animals, Herman’s Hermits, Marianne Faithfull, The Kinks, the works of Norman Luboff (Yellowbird) as well as the current songwriters Ben Margulies (co-writer of Mariah Carey), Devvon T McLeod (pka Devvon Terrell) and the Cameo Parkway masters by such artists as Chubby Checker, Bobby Rydell, Clint Eastwood, The Dovells, ? & The Mysterians, The Tymes and Dee Dee Sharp. ABKCO’s recordings are of the highest resolution audio quality available. We were the first label to launch our entire catalogue on hybrid SACD and continue to make our catalogue digitally available in the highest resolution audio quality available, partnering with companies including HD Tracks, Acoustic Sound and HIGHRESAUDIO for DSD downloads. ABKCO is at the forefront of new technologies in the entertainment field and is in active development of several multi-platform projects, theatrical productions and innovative educational tools to ensure its catalog is enjoyed by generations of fans for years to come. The company was founded in 1949 by Frank McIntosh. The company designs and produces audio amplifiers, stereo tuners and other consumer electronics products. Ownership: Single Owner Connections: RCA inputs and screw terminal speaker connections. General Sound: Smooth, uncolored, undistorted natural and clean Cosmetic Condition: 7/10 = Good. One or two minor scratches. Working Condition: Working perfectly and tested in our lab and listening room. Included: Just the unit and power cord. Packing: Will be packed using our highly developed in-house process and custom packing materials. Specs: Intermodulation Distortion: Less than 0.5% for any combination of frequencies from 20 cycles through 20,000 cycles if instantaneous peak power is below twice the rated power. Internal Impedance: Less than 10% of rated load impedance Input: Input impedance: 250,000 ohms Input sensitivity: 0.5 volts to 30 volts through gain control. 2.0 volts with gain control turned to dot indicator. Power Requirements: 117 volts AC, 50/60 cps Uses 200 watts at rated output; 85 watts at zero signal output. Fuse 2.0 Amp Slo Bio Tube Complement: Voltage Amplifier 1 x 12AX7 Phase Inverter 2 x 12AU7 Drive Amplifier 2 x 12BH7 Output 4 x 7591 Frequency Range: +0, -0.1 db 18 cycles through 30,000 cycles +0, -0.5 db 18 cycles through 60,000 cycles At one-half rated output: +0, -1 db 14 cycles through 100,000 cycles Noise and Hum: 90 db or more below rated output Output Impedance: Stereo or Twin Amp: (Center tap internally grounded) 600 ohms (One side internally grounded) 4 ohms, 8 ohms, 16 ohms, 150 ohms, 200 ohms Mono: (Center tap internally grounded) 300 ohms Dimensions: Chassis dimensions: 14-1/2″ long x 9- 1/8″ wide x 7 high. We start with a visual inspection of all internal components to make sure that there are no signs of heat stress or damage. Capacitors are checked for telltale signs of predictive failure including bulging, shrunken wrappers, or physical leakage. We also inspect resistors and other passive components for signs of overheating. If tube arcing has occurred in the past we can usually spot discoloration on the output tube sockets. On vintage units we often spot check select capacitors for value and ESR. If the amplifier passes visual inspection, we move on to a full test of all of the tubes. We use an Amplitrex AT-1000 Tube Tester which is capable of testing both emission and Gm with a high degree of accuracy. We document the results of each tube and replace any weak or suspect tubes before proceeding. When we power on tube amplifiers for the first time we usually use a variac and current limited AC supply and slowly raise the voltage up to nominal mains level while monitoring plate, screen, filament, and negative bias supply voltages where applicable. If everything is in order we feed a low level test signal into the amplifier’s input and monitor its output on an oscilloscope across an 8 ohm dummy load. At this point we are just looking to verify basic function and confirm that the output transformers are not damaged. Once we have verified that the amplifier is safe to operate, we connected it to full mains power. For cathode biased amps we monitor the plate to cathode voltage to determine if the output tubes are operating in a safe range. Once the output section is verified we move onto bench evaluation. We start by feeding the input of the amplifier with a low level 1KHz test signal, slowly increase its amplitude while monitoring the amplifier’s output on an oscilloscope for signs of noise, clipping, distortion, or improper channel balance. We continue increasing the signal level until the amplifier reaches clipping. At this point we take an output power measurement and compare it to the spec sheet of the amplifier to verify proper performance. We finish off the bench evaluation with a 1KHz square wave check and a 20Hz to 20KHz sine sweep to assess the amplifier’s frequency response characteristics. This battery of tests will usually reveal if the amplifier has any issues that need further attention. Before the device leaves the bench, we perform a listening test with actual music using a variety of preferred test tracks. Our benches are outfitted with familiar monitor speakers which help us identify inconsistencies that will not always show up on our test gear. The main things that we are listening for are hum or noise with no signal present, proper center image, clicks, pops, or any other obvious undesirable audio characteristics. If the unit passes all of these tests it is moved to our long term testing rig where we simulate real word operating conditions for 6-8 hours. For tube amps we like to run this test at least twice. This allows us to monitor the unit for signs of thermal runaway or intermittent issues that only crop up when it has fully come up to temperature. We find this step to be essential, especially for vintage units. SkyFi Audio – Curators of Vintage Audio Gear. No mid-fi, no gimmicks, no junk. Each piece of equipment is cosmetically restored and fully tested in our well-equipped lab by an engineer with 30+ years of experience in the HiFi world. Please note we are not a repair shop and only restore what we own. If we don’t have the original packaging, we use heavy-duty double-ply corrugated boxes with custom made to your item SealedAir Instapak expanding foam custom inserts. In many cases this has proven to be better than the original packaging! We also use high quality fiber reinforced tape to seal our packages. We have too many items for sale and it’s nearly impossible to keep track of offers outside of the official system. Our items are available for pick-up. No additional information at this time. You might also like. Dynavector 10×3 High-Output MC Phono Cartridge. Music Reference RM-5 MK II Tube Preamplifier with Phono. Music Reference RM-9 Tube Amplifier With EL34′s.
