McIntosh MA6100 Integrated Amplifier w/Original Box

Description: McIntosh MA6100 Integrated Amplifier w/Original Box - Serviced McIntosh MA6100 Integrated Amplifier w/Original Box - Serviced General: While this may look like a McIntosh C28 or similar preamplifier from this era, don't be fooled. This is a full-featured integrated amplifier from the 1970's capable of driving most speakers. It can provide 70W per side with clean, stable, and signature sweet McIntosh power. Dual phono inputs are a nice touch! It's also a great match to the classic McIntosh MR71 tuner to form essentially a very capable receiver. This MA6100 arrived with solid bones, and after basic intake testing quickly entered our service queue. We replaced a multitude of parts that were out of spec or known to have potential issues. This integrated is now working beautifully. SkyFi Cosmetic Notes: Light scratching is present on the top apron cover, chrome shows some pitting. RCA input and output jacks were polished but have some pitting. The preout / main in jumper set is not original. The front faceplate glass has a very minor imperfection in the top left corner. The original box shows significant wear from age and long term storage, and is missing two of the original cardboard packing inserts. SkyFi Technical Notes: This amplifier was serviced in house at SkyFi. We replaced the electrolytic and tantalum capacitors on all of the boards. This included the output driver cards, regulated power supply, and preamp circuits. The lamps were checked and replaced as needed. All controls were cleaned and the tone control adjustments were set for ideal frequency response. Note: we commonly see volume controls in this era of Mac that have less than ideal channel balance. This means that the amplitude of the left and right channels may not exactly match for the entire rotation of the control. We found that this affect is present in this control in multiple ranges. Adjustment of the balance control may be necessary from time to time to retain proper center image placement. Brand Background: McIntosh Laboratory is an American manufacturer of handcrafted high-end audio equipment based in Binghamton, New York. 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 outputs, Captive power cord, Speaker spring terminals, three AC Power outputs General Sound: Smooth, uncolored, undistorted natural and clean Cosmetic Condition: 8/10 = Very Good. Excellent front faceplate, one minor flaw on chassis side or top. See our detailed rating description here. Working Condition: Working perfectly and tested in our lab and listening room. Included: Unit and box Packing: Original Manufacturers Packing Specs: Power output: 70 watts per channel into 8Ω (stereo) Frequency response: 20 Hz to 20 kHz Total harmonic distortion: 0.2% Damping factor: 50 Input sensitivity: 2.5mV (MM), 300mV (line) Signal to noise ratio: 76dB (MM), 90dB (line) Output: 300mV (line) Speaker load impedance: 4Ω to 16Ω Dimensions: 16" W x 5 7/8" H x 13" D Weight: 34 lbs. Approximate Age: 1972 Testing Process: 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 the PCBs for discoloration from resistors or transistors that may have been running hot. On vintage units we often spot check select capacitors for value and ESR. If the device has the ability to decouple the preamplifier from the power amplifier, we remove the jumpers and independently test each section. If the device cannot be decoupled, we assess the electronic condition of the piece by analyzing the speaker level output only. We start by connecting the "Pre-Out" jacks of the integrated to a Sencore PA81 Power Analyzer which simulates real world loading conditions and gives us an oscilloscope interface. The first order of business is checking that the volume control works smoothly throughout its entire range with acceptable channel balance. This is accomplished by feeding a 1 KHz sine wave into one of the preamp’s line level inputs while monitoring the preamp’s output on an oscilloscope. We then switch to a 1 KHz square wave to test the tone controls, loudness function, and filters where applicable. During this step we are watching for equal alteration of the test signal by both channels. This also helps us identify dirty controls that will need treatment. Once the basic line stage functions are verified, we test each input individually. This is especially important for devices that use relays to select their sources. If the preamp section is equipped with a phono stage we test that as well. We use an inverse RIAA filter which allows us to feed a reference test signal into the phono input with the proper RIAA equalization and level. A square wave or sine sweep is uséd to verify that the device’s phono stage is faithfully reproducing the RIAA curve. Next we test the power amplifier section by connecting the integrated amplifier speaker outputs to a Sencore PA81 Power Analyzer which acts as a dummy load, DC offset monitor, and oscilloscope interface. We start with a low level 1 KHz test signal at the "Main In” jacks and slowly increase its amplitude while monitoring the 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 1 KHz square wave check and a 20 Hz to 20 KHz 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. If the preamp and power amp both pass these tests, we reconnect the sections and verify that the preamp section can drive the power amp to rated power with a 1KHz tone on one of the line level inputs. 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 moves to our long term testing rig where we simulate real word operating conditions for 6-8 hours minimum. This allows us to monitor the unit for signs of thermal runaway or intermittent issues that only crop up when the unit has fully come up to temperature. ---------- SkyFi Audio - Curators of Vintage Audio Gear SkyFi Audio is a small startup business specializing in the purchase, reconditioning, and reselling of high end audio equipment. We only buy equipment that we admire and are passionate about. 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. If it does not meet or exceed the original manufactures specifications, it will not be sold. We are very selective about the equipment we purchase, focusing on mostly analog, high-build quality, American, and European built units. Please note we are not a repair shop and only restore what we own. ---------- PURCHASING GUIDELINES: 1) This item will be professionally packaged and insured for safe transit to your home unless you opt for local pickup from our shop. All local pickup items are only wrapped in industrial strength clear stretch wrap if the original manufacturer packaging is unavailable. Local pickup is available in Glen Rock, NJ, 07452, just a half hour drive from Midtown Manhattan, with convenient parking near our building. 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. Lightweight items will be bubble wrapped and shipped in a high-quality box. 2) We will not review or accept any offers that do not go through the official eBay system. We have too many items for sale and it’s nearly impossible to keep track of offers outside of the official system. Please do not message, email, or text any offers. 3) All listings are eligible for the eBay Global Shipping Program unless the item exceeds the maximum weight/price requirements to your country. If this is the case simply message us via eBay. We only accept bank wire transfers for international payments and frequently ship worldwide via UPS. 4) Please ensure your shipping address is correct within eBay as we will ONLY ship to the eBay/PayPal Confirmed Shipping Address. No exceptions. 5) eBay may charge and collect sales tax to your state/jurisdiction which we have no control over. eBay v1.8 × Buy now and save! Tell a friend Visit store Watch now Postage info UPS Ground - $0.00 Local Pickup - $0.00 Click the Postage tab above the listing description for more info Additional delivery notes PICK UP OPTION Our items are available for pick-up. Pick up procedure is as follows: Purchase the item through eBay Email us to coordinate pickup PAYING VIA PAYPAL We accept PayPal on our all our items so you can shop with confidence. Simple choose the PayPal option when proceeding through the checkout. Additional Information No additional information at this time Ask seller a question You might also like Dynavector 10x3 High-Output MC Phono Cartridge Music Reference RM-5 MK II Tube Preamplifier with Phono Music Reference RM-9 Tube Amplifier With EL34's Marantz Model 150 Vintage AM/FM Tuner with Scope Contact To contact our Customer Service Team, simply click the button here and our Customer Service team will be happy to assist. 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Price: 4270 USD

Location: Glen Rock, New Jersey

End Time: 2024-10-05T16:13:59.000Z

Shipping Cost: 0 USD