Pioneer Elite C-90 Reference Preamp w/MM Step-Up Transformer Phono Stage


Great match to our Pioneer Elite M-91 amplifier that we just listed.

Click here to view all Pioneer Elite products current listed on our site

Tested in our lab and working perfectly requiring no technical intervention.

Plus this is preamp has a dedicated page on The Vintage Knob website so you *know* it's something really special:

"The C-90 is the original; it was however distributed in two versions, both named "C-90":

- one had only three video sources selectable from the left row of black pads, named aux1 > aux3

- the other had five of those inputs, named exactly as on the C-91.

The panel is however identical with a "blank" pad shaped as the other buttons covering for the two absent inputs.

The C-90a (ELITE C-91 in the USA) is the 1988 updated version of the original 1986 C-90; the update mainly consists of mechanical strengthening (thicker and two-plate top) and the addition of six S-Video terminals - 5 inputs plus 1 output.

But, as for the two versions of the original C-90, things are not so simple for two versions of the C-90a were delivered:

- one that does not have any video terminals,

- one that has S-Video inputs besides the regular composite terminals!

Very much Sony-like but probably due to both varying introduction schedules for the S-Video format and the desire for a more "audiophile" version here and there. I guess - but I dare not think what this would have become if Pioneer had decided to add a digital PCM section as in the contemporary Sony TA-E77ESD!

Anyway, all four versions sold well and were all built to exacting standards: three transformers and separate windings + regulations to separate at best the video and audio sections, thick aluminium top plate, polymer-filled insulators, copper plated screws, honeycomb chassis, film capacitors and sealed gold-plated relays.

The two transformers are insulated from the chassis and noise currents are shunted with a bypass; caps are copper-coated (except the top) while the video board (if any) is located at the bottom of the enclosure and the audio board at the top.

The remote volume control uses an (I believe) ALPS pot but it is only a 2-gang - got to make some economies somewhere...

The power cord is however made of high-purity copper - got to give some in return of said economies.

Besides the five (or three) (or none - you get my drift) audio/video inputs (all with 10MHz bandwidth), three tape loops and two line inputs were at hand, along with a hybrid MM/MC phono stage and programmable "smart remote" control.

The front flap holds the MC phono cartridge impedance selector, one of the tape loops, an auxiliary input, the bass/treble/balance pots etc."

SkyFi Cosmetic Notes: 

• Slight discoloration on certain areas of the flip down front panel.
• Marks on top cover from unit stacking over tine.
• Dinged rear corner of left side panel.

SkyFi Technical Notes: 

These usually need bulk relay replacement but this is a later version that used an upgraded board and *sealed* relays. All functions tested and working with no channel dropouts or other distortion.

• All inputs tested.
• EQ good with no noise.
• Volume control smooth.
• Listening Test - PASS.
• No Video Functions Tested.

Click below to add our recommended matching cables from Kimber Kable, all brand new as SkyFi is an official Kimber dealer.

Kimber Kable - RCA Interconnects - Better

Kimber Kable - RCA Interconnects - Best

Kimber Kable - Phono Interconnects - Better

Kimber Kable - Flagship Tonearm Interconnects - Best

The SkyFi Testing Process for Preamplifiers:

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.

When we first power on a preamplifier we connect its RCA output 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 1KHz 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 1KHz 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 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 used to verify that the device’s phono stage is faithfully reproducing the RIAA curve. If the preamp under test has balanced inputs and/or outputs these are tested as well.

We finish up our bench testing with a listening test with our bench amplifier and reference speakers. During this test we check for hum or hiss that may not have shown up in earlier testing. We also check that all of the tone controls and filters perform as expected. If the preamplifier has remote control functions these are also tested. Preamps with tube circuits or complicated power supply topologies are connected at our long term test rig for extended stress testing under real world conditions.



Original Box

Not Included


Yes Included


Yes Included


Yes - Power Only

Physical Condition (Info Here)

7 / 10

Working Condition

10 / 10

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