Pioneer M-90 Vintage Amplifier - Tested to 200W - "Cosmetically Challenged"

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I can't believe these are already considered vintage! I personally installed many of these famed Elite systems when I was working as an installer in college. 

Unlike many components from this era, the Elite series delivers both inside and out.

Oh, and they also sound superb...

This model is quickly becoming our best selling amplifier this year. After identifying what a great model this is (on several levels), we've been sourcing them from all over.

Match it up with a Pioneer Elite C-90 currently in stock for a superb one/two punch.

We might even have the matching Tuner and CD player available too:

Click here to view all Pioneer gear on our site

The part/build quality of this amp is incredible. Twin mono construction with dual cast iron-housed transformers, big honeycomb heatsinks, beautiful orange VU power meters, solid aluminum knobs, copper-plated chassis and screws, high grade electrical components, huge speaker terminals, mirror metal finish - this was Pioneer's flagship consumer amp and it shows. 

One standout feature on this amp is that it offers *three* inputs, including two dedicated line level inputs that are controlled by a volume knob on the front. So you can use this with no preamp to avoid unnecessary circuitry. The last input is for a preamp/control amp and bypasses the volume knob. 

Fully tested in our lab where it performed as expected at 200 clean watts.

While we have several super clean examples available, this unit has some cosmetic deficiencies as listed bellow. It is however working properly and was fully tested in our lab. All burned out lamps were also replaced. Priced accordingly.

SkyFi Cosmetic Notes:

• Missing front flip down cover
• Scratch in meter face
• Distortion in lower plastic
• Cosmetic repairs performed to side panels
• Scratched selector knob

We just acquired a big lot of Elite components so standby for a full system video and review. Drop us a note if you're invested in the complete stack. 

Recommended Cables:

Kimber Kable - RCA Interconnects - Better

Kimber Kable - RCA Interconnects - Best

Kimber Kable - Speaker Cables - Better

Kimber Summit Series Monocle XL Speaker Cables (PAIR) - Best

Kimber Summit Series BiFocal XL Bi-Wire Speaker Cables (PAIR) - Best If Applicable 

Technical Specifications:

Power Output:
200 watts per channel into 8Ω (stereo)

Frequency Response: 
20 Hz to 20 kHz

Total Harmonic Distortion: 
0.003%

Input Sensitivity:
1V

Signal to Noise Ratio: 
125 dB

Dimensions: 
17.99" x 17" x 6.24"
(457 x 432 x 163mm)

Weight: 
60 lbs.
(27.3kg)

Approximate Age:

1988

The SkyFi Testing Process for Solid State Amplifiers:

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 amplifier passes visual inspection, we move on to a controlled power on sequence using a Sencore safety analyzer to monitor current draw in real time. Once the amplifier is determined to be safe to operate, we connect it to full AC mains for function and power testing. We connect the speaker outputs of the amplifier to a Sencore PA81 Power Analyzer which acts as a dummy load, DC offset monitor, and oscilloscope interface. We start with a low level 1KHz test signal at the amplifier’s input 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. If the device under test has both balanced and single ended inputs they are both tested at this time. 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. 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.Here for sale is a Pioneer M-90 amplifier. This amp came into our shop with burnt out lamps and distortion in both channels. On internal inspection we found some heat stressed components. We reflowed the solder joints on some suspect driver transistors which resolved the distortion issue. We also swapped out the lamps while the unit was on the bench. Both channels tested clean to the rated power of 200W into 8 ohms. This unit is fundamentally working but we recommend additional service for long term reliability.