Boston Acoustics A100s possibly need recapping?

super j

super j

Active Member
I previously posted about these speakers while trying to figure out the differences between series 1 and series 2. These are series 1 purchased by my mother around 1981. I cleaned them up and purchased new subs from Gordon. I got everything hooked up but the vocals seemed kind of muddled. Upon further inspection it sounded like one of the tweeters wasn't putting out like the other was. While toggling the balance back and forth listening for sound differences I realized that the sub wasn't putting out as much as the other either.

These speakers were stored for several years in a storage room under the back of my house. (House is on a slope plus an 8" step down going into the room.) I purchased the house from my mom and moved the speakers several months after moving in. The speakers were laid on their backs with one on top of the other several feet from the window with no subs in them. This is an open window with no glass only plastic covering it. There was a time period before I bought the house where the plastic was ripped down until I replaced it. I have no idea how long the room was open though. The water heater is also in this room. It busted and flooded the room one time also. Although the speakers were off of the floor it is possible that they got sprayed from the water heater or wet from the open window.

The speaker that was on bottom sounds great. The one on top was laying face up, subless, with the crossover open to the elements, so to speak. Does this sound like it needs recapping, new crossover, or something else entirely?
 
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super j said:
I previously posted about these speakers while trying to figure out the differences between series 1 and series 2. These are series 1 purchased by my mother around 1981. I cleaned them up and purchased new woofers from Gordon. I got everything hooked up but the vocals seemed kind of muddled. Upon further inspection it sounded like one of the tweeters wasn't putting out like the other was. While toggling the balance back and forth listening for sound differences I realized that the woofer wasn't putting out as much as the other either.

These speakers were stored for several years in a storage room under the back of my house. (House is on a slope plus an 8" step down going into the room.) I purchased the house from my mom and moved the speakers several months after moving in. The speakers were laid on their backs with one on top of the other several feet from the window with no woofers in them. This is an open window with no glass only plastic covering it. There was a time period before I bought the house where the plastic was ripped down until I replaced it. I have no idea how long the room was open though. The water heater is also in this room. It busted and flooded the room one time also. Although the speakers were off of the floor it is possible that they got sprayed from the water heater or wet from the open window.

The speaker that was on bottom sounds great. The one on top was laying face up, wooferless, with the crossover open to the elements, so to speak. Does this sound like it needs recapping, new crossover, or something else entirely?
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Based on what you're saying, I'd try the speakers with a different amp, for starters.
 
I did reverse the channels so I could rule out the amp. The problem is the same through left or right.
 
Being that they are 26 years old, it definitely wouldn't hurt changing out the caps and resistors (if any). You could use just good 'ol electrolytics which would be the most economical or step up a little to the Dayton poly caps (Parts Express)...or even higher. Now, if you can actually dismantle the crossover from the one speaker and put it into the other, THAT would be a test to do. Or, transfer one driver (mid, tweeter, etc) from one cabinet to the other just for the sake of trying it. It's all about the process of elimination and costs nothing to do that.

Do any of the caps look odd per chance?
 
Here's a pic of the crossover. Everything looks fine to me although I really have no idea what I'm doing. The brown one on the left would be a resistor, right? What's the one on the right called? Should it be replaced?

DSC01506.jpg
 
On the upper right is the inductor. You shouldn't need to touch that. The resistor's probably fine too, and I'd guess that the caps aren't dead, but your speakers would benefit from a recap. Dayton precision caps would be an economical, nice choice. If it comes down to it, spend more money on the 4.7uf cap than the 20uf, where you can use a budget cap.

Check that your speakers aren't wired out of phase, either.
 
I found one of those power resistors dead (open) in one of my Q2's. In series with the drivers, so drivers didn't work. If this was in parallel it might just change the output.

The junction of the three wires from the resistor and two caps looks funny. Can't really see a solder blob, and the wires look like they still have the insulation on. Could very well be the picture, but thought I'ld mention it as a potential.
 
Kencat said:
I found one of those power resistors dead (open) in one of my Q2's. In series with the drivers, so drivers didn't work. If this was in parallel it might just change the output.

The junction of the three wires from the resistor and two caps looks funny. Can't really see a solder blob, and the wires look like they still have the insulation on. Could very well be the picture, but thought I'ld mention it as a potential.
Click to expand...

It's just the picture.
 
Could someone point me in the direction of what caps to buy? I have no problem doing this myself but I was looking on parts express in the Crossover Components section and was unsure of what to get. The two caps in my speakers are 4.7 uf and 20 uf both 50v and the ones on parts express are 200v and higher.
 
Higher voltage ratings on the caps are fine it's the "uf" number you want to keep as close as possible. The higher the voltage rating, the more (potential) the caps can handle with minimal tolerance shift.

Fortunately, you have pretty standard caps where you don't have to parallel a couple together. Like Redboy was saying, spend more on the 4.7uf cap. Something like this one is less than $2 each and the better version is only $3.60. Both are Poly caps and the latter one has a lower tolerance of 1% (less shift in crossover). On the 20uf, something like this Poly is only $5 which would be my choice. Otherwise, just use a basic electrolytic cap although they don't show an exact 20uf. I'd personally get the 20uf poly (stated earlier) because it's just not that much money.

While you're at it, go ahead and replace the 3-ohm resistors with something like this for only $.39.
 
Those are exactly the caps I would have recommended. If you wanted to go whole hog, try using Mills resistors for tighter tolerances - this one.

I'm a believer in using components with close tolerances, especially in crossovers where variances affect what you hear. You might want to skim over this thead . You can ignore the specifics related to my crossovers, and pay attention to some of the general concepts laid out by Bob.
 
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