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Author Topic: Pioneer Project 120 vintage speakers and crossover filter inspection  (Read 1326 times)

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Online Kiriakos GR

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I got today two cabinets of Pioneer Project 120  speakers ( just the cabinets with crossover filter).

Actually I rescued the cabinets from ending at local landfill, and more important reason about to rescue then this is the good condition of the wood (cabinets).
A bit of Google search helped me to find the age of those cabinets (1979-1980).

My findings by inspecting those cabinets, created to me very negative impressions.
Speakers cabinet looks nice but build quality screams budget Low-End work, and does not creates any bragging rights for PIONEER USA.

Cabinets are reasonably made and they are large, but crossover circuitry this is made by worst product design which I have ever seen in my entire life.
All parts they got assembled over a layer of cheap wood ( compressed paper) and all this it got glued over the cabinet.
There is no way to repair this crossover other than fiddling with components from it top side.

Basically I would not get in too much trouble if speaker cables was not cut off from the supposed PCB.
As is made this crossover I am unable even to create an schematic.

Polarity of cables this looks confusing to sort out.

Speaking of components I am going to mention capacitor values as help to any one wish to repair such a crossover.
Capacitors these are Nichicon Bipolar.
One cap for Tweeter this is 2.2uF 100V
One cap located right between two coils this is 5.6uF 100V
Last one this is 14uF 50V

Coils are made in Mexico.
Original cable input terminals (screws) this is made in Taiwan :)

Most weird thing this is that they use black wire as + Positive.
If this were a bomb ? I would had be killed    ;D ;D

And lastly I found a picture of original Tweeter speaker. 
Tweeter 6.5Cm EAS-05PH31S Japan  ( This is unknown to Google) 

   
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Online Kiriakos GR

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  • Join Date: May 2012
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    • ittsb.eu
  • job title: Industrial Maintenance Electrician
Re: Pioneer Project 120 vintage speakers and crossover filter inspection
« Reply #1 on: July 17, 2017, 10:45:06 PM »
With the help of my LCR using it as signal generator and with my Koss Headphones, I did managed to decode this three way Crossover.
I am not a speakers specialist and one coil in parallel with Mid-range line this confused me allot.

After decoding  ;D now everything looks clear, and I did rewire everything, and even replaced the speaker input terminals with a better one.

Now that I become an expert, I am going to repair and the second cabinet.
Despite the fact that those cabinets were shipped with low power drives, these cabinets are quite large, and able to offer sweet bass.
While these speakers designed to be budget Home-Audio speakers, in 80s the sounds where mostly made of natural instruments.
Therefore for people with taste for modern electronic music, and heavily distorted bass,  these speakers are not made for them.

PIONEER in Greece (90s) were quite popular, mostly because of the tremendous availability of drives as spares, DIYers was buying PIONEER drives and made their own cabinets.
Also PIONEER speakers was easy to repair by a simple drives exchange.
But PIONEER Crossover was coming only with PIONEER branded pair of speakers (Never seen single Crossover in retail market as spare part).
Generic Crossover with PIONEER drives among with DIY cabinets, this never worked well.

The King of quality made Crossover this was PHILIPS in Belgium.
Source of innovation speaking of new technology tweeters, this was again PHILIPS in Belgium.
True sound speakers development and product design testing were made again by PHILIPS in Belgium.

Therefore for audiophiles like me back then (90s) our choices were limited.
a) B&O which no one can afford.
b) PHILIPS for affordable high Performance.
c) JVC or Panasonic Technics ( Medium performance from reliable brands)
d) PIONEER drives and DIY speakers.

Today I am not in need for another pair of speakers, but these ones I am going to keep them, to resale or use them in a later time, most worthy part in them this is the design of PIONEER Crossover, with new pairs of drives, these speakers will deliver a much pleasant sound than most modern budget Asian pairs of speakers. 


 
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