Concept 3.5

Concept 3.5 Faceplate

The Concept line of stereo receivers were offered by Pacific Stereo as a house brand. The top of the line was the 16.5. Near the bottom of performance range was the Concept 3.5 receiver. The low end was the 2.5. Despite being an economy model it was actually a pretty good little receiver. It produces 35 watts per channel and has appealing looks.

Concept 3.5 Left

Concept implemented an interesting design with their push button controls. As you can see there is a built in LED in each push button. The LED’s make it easier to see which functions are active in low light or darkness. The Concept 3.5 also has a big blocky type switch for the AM/FM/Phono control similar to those used by Yamaha.

Concept 3.5 Right

The Volume and Tone control knobs have multiple detents for more precise adjustment. Concept called the 3.5 a ‘User Oriented’ stereo which means it had all of the basic features and was offered at an affordable price.

Concept 3.5 Lamps

As you can see in the picture above, the Tape Monitor button LED’s glow red when the button is depressed while all the others glow green. The 3.5 utilized a 3 gang tuner, full Quadrature detector and Phase-Lock Loop circuitry. You can see two small cutouts just above the FM 88 and 108 MHz symbols on the analog tuning dial. The left square cutout is the Stereo indicator light. The right is the Protector Activated light which comes on when there is either a short circuit in the speaker circuitry or an overload of the receiver.

Concept 3.5 Inside

The Concept 3.5 weighs in at just over 27 pounds and measures 18 3/8″W x ” 6″H x ” 15″D. It also has Rosewood patterned vinyl covering pressed plywood. Overall it’s a nice little receiver.

Concept 3.5 Back Panel

Obviously the most coveted of the Concept receivers is the monster 16.5.  But, if you don’t want to spend absurd money for a huge receiver then the smaller Concept receivers might be a good fit.

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5 thoughts on “Concept 3.5

  1. The line of Concept receivers are nice. The quality of parts, straight forward design, and sound output are well matched for the listeners ears and eyes. In other words- it sounds good and looks good. I have a 4.5D and it definitely keeps up with the larger items of my collection.
    I’ve noticed there’s not much information available (manuals, etc) related to specific models. This website is gold!

  2. i’m putting my 3.5 thru the paces..recapped with stock values.

    no service manual so i have idle current @ 15mv across one emitter resistor. it idles cool and no crossover distortion.

    1khz both channels driven…volume control one detent below clipping

    50wpc @ 8 ohm–.07% thd

    65wpc @ 4 ohm–.14% thd

    itsa sleeper.

    1. Hey Joe! Do you have any more information on what values you set for this concept 3.5?

      I’m having a tech work on it right now and with little to no information/schematic it’s hard to find anything.

      I’d appreciate anything you’ve got! Thank you

      1. i used the 4.5 schematic, the 2 are pretty similar. the tone sections are identical. the tuner i believe is identical. the 3.5 has a better phono stage. i also like the 3.5 quasi comp amp vs the 4.5’s comp. amp…i have both. as far as values??? idle current was adjusted by making sure there was no crossover distortion on the scope and making sure that the outputs did not run hot. like i said, 15mv across one emitter resistor. dc offset gets adjusted to 0vdc

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