The Alpine 3506, A 35 Years Old Car Amplifier Today

While I am having a little break to work on the Bottlehead Crack headphone amplifier, I suddenly find this little gems.

This is an Alpine 3506 stereo car power amplifier that you only can find it brand new 35 years ago and fortunately I still can find it today with all the original accessories completed. So, it is a nostalgic moment, as I always said, opening the new old stock product is just like having a time machine.

As you should expecting from this kind old product, the box is rarely in perfect condition. Same like this Alpine 3506, in my opinion, it is still in good condition and worth to spent.

The box tells everything you need about this product.

All measurement and specification are stated on there.

This Alpine 3506 is only 20 watt per channel.

It is seems like very small watt for today standard right? Yes it is, but still depends on what you comparing with. If you see most of car head unit already having 50 watt per channel, I can tell you that you've been fooled by marketing gimmick.

A little knowledge to be share, the watt number is not a single measurement to believe for a whole amplifier performance. The distortion after that numbers is the keys. Such this example, the Alpine 3506 is 20 watt at 0.04% distortion while car head unit is 50 watt at mostly at more than 10% distortion. You only can find it on the manual included the head unit that you never read it for sure:)

That difference in distortion numbers is huge different in the sound quality. While pumping this Alpine 3506 more power up to 35 watt, the distortion is increasing to 8%. That is what I call a degradation in sound quality. Anyway, watt is watt, it is measure the heat.

So I always better not to depends to a single measurement while personal listening test is the main measurement.

Looking to this 1985 built amplifier is have their brothers, is the 3505. It is more smaller and the 3508 is way bigger than this one.

Speaking about Alpine numerical series, I still cannot understand the meaning of that number. It is confusing. But let's continue see inside the box and you will know that this Alpine 3506 here is also small in dimension as well.

The product is protected with Styrofoam, very common for packaging on 80's.

The accessories included are power cable, extra fuse and mounting hardware.

And this is the typical Alpine owner's manual. If you grow in car audio in this era, you will probably seen this many times.

And this is how we setup the car audio in that era!

High power for the rear deck speakers, mostly oval speakers. Then open up the trunk and let's the party begin. No front sound stage, no center imaging, it is all about loud and clear.

This Alpine 3506 is aim to become like home audio sound quality.

It is stated on it's manual.

Here it is, the product it self. 

My hand is to scale. So you can imagine this amplifier is considerably small in size.

The design is old, but still match with today standard, for home audio, not car. It is just like a class A amplifier that Nelson Pass build for times.

I wish this Alpine 3506 is bigger than this, I would consider to using the case only for my next home amplifier project. It is such a pretty design for an amplifier.

The very uncommon for a car amplifier these day is using home amplifier speakers connector like this. I could not complaining at all since at the very first time on this Alpine 3506 manual, they already said that this is just like home audio equipment. So the design and the connector is probably at the same design.

This power cable extension is intended to connect this amplifier to the battery in the engine hood.

Next, I curious how is the components inside this amplifier.

The first thing you notice once open up the top cover of this amplifier is the big capacitors and the size toroidal that you can find in much bigger amplifier today.

There is two capacitor with the same size, means this amplifier runs fully dual rail power supply and it is very common for the 80's to 90's power amplifier that using this Nichicon capacitor brand for power supply section.

Looking to the capacitor rating is 3300uF, it is big for this 20 watt power amplifier which the same rating you can find in early year 2000's Rockford Fosgate amplifier.

The voltage rating on the capacitors are tells everything. Most high quality car amplifier has dual rail power supply each around 30 - 35 volt just like this. Such a beefy power supply for this little amplifier.

Still talking on the power supply section, this big transistor package is capable for higher wattage supply. It is very related to what I am talking about this high rating power supply on Alpine 3506. Total power transistor is 4 pieces, 2 on each side.

And this is the amplifier section. The power transistor is much smaller compares to the power supply transistor. It is push-pull design amplifier which very common for the high performance amplifier until today.

The bottom layout PCB is single layer, it is simple and you will never find fiber glass PCB like today standard for high quality unit.

Initially, I want to using this car amplifier in my car.

But looking how neat and original this amplifier is, I guess I will put it inside the box and hang in my collection bin instead.

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