Vintage Loud-Speaker Drive Units

 



 

Amazing Alnico Speakers

First off, what are we even talking about?

Well, we mean the type of magnet used in a speaker drive unit. Any conventional driver will use a magnet. There are two types commonly used: AlNiCo and Ceramic.

There's quite a fan base for these vintage drive units and many claim they sound better than ceramic speakers. The question is do they actually sound better and if so why? This stir in the HiFi underworld appears to have been noticed by today's companies, who now offer their own AlNiCo units. So is there something in it?

What is Al-Ni-Co (Aluminum-Nickel-Cobalt)

Its an alloy magnet system and was very common in the 60s. Its more expensive than ceramic magnet material, so logic would dictate that it was used for a reason. Saba, Isophon, Goodmans, all top manufactures back in the day and all of them used AlNiCo magnets in many of their drive units.

"the AlNiCo sound"

This is all about compression and it only happens due to the nature of the AlNiCo magnet.


AlNiCo magnet has a delicate magnetic field, easilly drained by other forces. So when you send a signal to the voice coil in a speaker, you are generating an opposite magnetic field. The field generated in the coil pushes away from the AlNiCo field, causing the cone to push out. When you swap the polarity, the reversal happens.

The field in the coil is also interacting with the AlNiCo, it looses some of its power as the coils field is present.

When playing music, the louder the volume the greater the field in the coil. The AlNiCo magnet is constant but the coils field is jumping around and switching direction. The bigger the coils field, the more power sapped from the AlNiCo.








So to recap, when the fields are interfering, the voice coil field weakens the AlNiCo magnets field. As you increase the signal, the greater you weaken the AlNiCo.

If you weaken the magnet on a speaker, it becomes less efficient (you get less output volume). This is happening with every movement of the voice coil, tiny tiny amounts and at extremely high speeds.

So the AlNiCo magnet system is smoothing the sound, or, to be more accurate, compressing.

So there is a difference with AlNiCo speakers and to my ears they do sound "better" but of course there are many other elements to a speaker and a well designed ceramic speaker will sound better than a poorly designed AlNiCo.

Hitachi HS-500 Speakers 1969

Hitachi HS-500

What can I say, these speakers are simply divine!

The drivers are both alnico! The 8" bass is an amazing piece of design. Ive never really liked horn tweeters but these are perfect. Just one of these speakers gives a massive sound. They can be bi-amped as well! 1969!! Bi-amping! Thats when you realize how special these speakers are.

                         

Sansui sp-2000 Speakers

Sansui SP-2000 vintage speakers.

A 4 way speaker consisting of 6 drivers per side. 12" bass with alnico magnet system, all other drivers are alnico as well. 2 mid-range, 2 tweeters, a super tweeter and a massive bass port. 

Made in Japan by Sansui 1968

30hz - 20Khz test chamber

25hz - 20Khz normal room

max power 70watts

8 ohm impedance

spl 101db

cross over points 1500hz, 5000hz, 10000hz

653mm H x 380mm W x 323mm D

Teak veneer

20kg each

 
              


These should have been everything I was looking for but sadly, a major disappointment. To be fair, I think the cross overs were way past their best. All I could hear was mid-range, loads of it, not good mid-range either. By adjusting the tone controls on the back I could just get them bearable. Shame, I think in a bigger room I may have seen their magic but in my setup, they had to go. Back came the IMFs, more on those later.