Crossovers
It appears that the A100 evolved during its 1980's production life. The original model (series 1) had the woofer midway between the top and bottom. The later models (series 2 and 3) had the woofer nearer to the top and nearer to the tweeter; the later enclosure was also 2" taller than the earlier series 1.
The above changes, as well as the new tweeter that was introduced in the series 2, probably led to the crossover design changes.
I just picked up a pair of the A100, series 2. The crossovers have two inductors (1.65 & .50 mh) , two capacitors ( 6 & 16 uf) and one resister for the tweeter ( 2 ohm).
An earlier crossover had both a different number of components & and different component values.
With my pair of A100s, although one of the 16uf capacitors had migrated to 20uf due to age (and both inductors were of low quality) the sound captivated me enough to rebuild the crossovers using better air coil inductors that I had laying around, and some Audyn Q4 capacitors that I purchased from parts express.
The crossover upgrade resulted in modestly better sounding speakers. But I should point out that larger air coil inductors, and film caps, are much more expensive than the original crossover parts. And the project could easily require a good days work, depending on your setup and experience.
Here are some images of A100 crossovers (from the internet) and a schematic I drew of the A100, series II crossover--
* * * * * * * * * * * * * * * * *
The original A100s (series 1), with the round SEAS tweeters, crossed over at 1600 hz :
* * * * * * * * * * * * * * * * *
The series 2, with the rectangular Boston made tweeters, crossed over at 2000 hz :
* * * * * * * * * * * * * * * * *
This is a later, series 2 or 3, crossover :
* * * * * * * * * * * * * * * * *
My series 2 crossover contained only a single resistor. Here is the schematic I drew :
(the woofer is 4 ohm nominal, and the the tweeter 6 ohm nominal)
It appears that the A100 evolved during its 1980's production life. The original model (series 1) had the woofer midway between the top and bottom. The later models (series 2 and 3) had the woofer nearer to the top and nearer to the tweeter; the later enclosure was also 2" taller than the earlier series 1.
The above changes, as well as the new tweeter that was introduced in the series 2, probably led to the crossover design changes.
I just picked up a pair of the A100, series 2. The crossovers have two inductors (1.65 & .50 mh) , two capacitors ( 6 & 16 uf) and one resister for the tweeter ( 2 ohm).
An earlier crossover had both a different number of components & and different component values.
With my pair of A100s, although one of the 16uf capacitors had migrated to 20uf due to age (and both inductors were of low quality) the sound captivated me enough to rebuild the crossovers using better air coil inductors that I had laying around, and some Audyn Q4 capacitors that I purchased from parts express.
The crossover upgrade resulted in modestly better sounding speakers. But I should point out that larger air coil inductors, and film caps, are much more expensive than the original crossover parts. And the project could easily require a good days work, depending on your setup and experience.
Here are some images of A100 crossovers (from the internet) and a schematic I drew of the A100, series II crossover--
* * * * * * * * * * * * * * * * *
The original A100s (series 1), with the round SEAS tweeters, crossed over at 1600 hz :
* * * * * * * * * * * * * * * * *
The series 2, with the rectangular Boston made tweeters, crossed over at 2000 hz :
* * * * * * * * * * * * * * * * *
This is a later, series 2 or 3, crossover :
* * * * * * * * * * * * * * * * *
My series 2 crossover contained only a single resistor. Here is the schematic I drew :
(the woofer is 4 ohm nominal, and the the tweeter 6 ohm nominal)
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