Boston acoustic a70

[Miker1102]

So I picked up a pair of these for 75 dollars locally to use for the fronts of a small 5.2 room that is my first foray into surround. I read the reviews and people seem to really like these but they are fatiguing to me at mid level when I listen to rock music. I was using some Sony vintage rack towers that I think sounded pretty good , however, being a novice with sound I just figured maybe I don't know what good speakers are because the Sony ones are so poorly reviewed so I bought the a 70s. The room I am in is an L so I am about eight feet from the front speakers. Any suggestions? I am listening mostly to high res, sacd, and blu ray audio. I wish I was better with sound terms to describe the way the speakers sound to me . All I can think of is they are to "bright" for my tastes or maybe a three way tower adds more dimension to the sound? I appreciate any type of feedback.

 

[gene_stl]

You could be experiencing any number of things. You have to learn how to separate things out in order to check them. Maybe the speakers aren't healthy. Or maybe one of the amplifier channels is blown or worse "half blown" wherein one polarity of output devices is dead or sick and it still can make loud sound but harshly distorted.

You also could be hearing what actually IS on the hi rez file.
Find something that always sounds good to you. Take it to somewhere else like a stereo store or another serious hobbyist and learn exactly what it has on it and what it should sound like and then you will have a reference to use.

You also could look into some test equipment or a friend who has it and knows how to use it. An oscilloscope will reveal a misbehaving amplifier or other
piece in the signal path pretty easily.

You also could have a deranged frequency response. You can buy an inexpensive microphone and REW which also can pick up various problems and measure the flatness of your system in the room it is in.

I wouldn't lend too much credence to reviews unless you know the reviewer. Opinions are like you know what. Everybody has one.

 

[Putterman]

The first thing to check is to see if the surrounds on the woofers are intact. The A70 foam surrounds are notorious for deteriorating over time. This will reduce the bass. You can order new surrounds through various online sites. It's a moderate pain to replace them and there are some places that will do it for you. There are plenty of you tube videos on how to replace the surrounds your self.

 

[Doug G.]

And, being a sealed system (I sold them back in the eighties) there can be no air leaks in the cabinet or the entire response will be ruined. This is true of any acoustic suspension (sealed) system.

When you gently push the woofer cone in, it should return fairly slowly and not immediately.

Doug

 

[ar surround]

So I picked up a pair of these for 75 dollars locally to use for the fronts of a small 5.2 room that is my first foray into surround. I read the reviews and people seem to really like these but they are fatiguing to me at mid level when I listen to rock music. I was using some Sony vintage rack towers that I think sounded pretty good , however, being a novice with sound I just figured maybe I don't know what good speakers are because the Sony ones are so poorly reviewed so I bought the a 70s. The room I am in is an L so I am about eight feet from the front speakers. Any suggestions? I am listening mostly to high res, sacd, and blu ray audio. I wish I was better with sound terms to describe the way the speakers sound to me . All I can think of is they are to "bright" for my tastes or maybe a three way tower adds more dimension to the sound? I appreciate any type of feedback.

Miker, I'm going to give you some deep-dive information on how to modify (improve) the sound of these speakers. Take a look at the post of June 30, 2017 in this thread:

https://community.classicspeakerpag...cs-a70-schematic/?tab=comments#comment-113609
A few things:
- I would not replace the gray Unicon capacitors that came stock with the A70. In my opinion, replacing the Unicon capacitors in these particular speakers with modern day NPE or polypropylene capacitors make thems sound worse and more fatiguing.

- The first thing I would try is installing these 0.01uF film and foil bypass capacitors across the existing Unicon capacitors:
https://www.parts-express.com/Dayton-Audio-DFFC-0.01-0.01uF-400V-By-Pass-Capacitor-027-450They are cheap...$0.99 each.

- If that still doesn't do the trick for you, add these 0.51 ohm resistors in series with the Unicon capacitors:
https://www.parts-express.com/Dayton-Audio-DNR-0.51-0.51-Ohm-10W-Precision-Audio-Grade-Res-004-.51They are brutally expensive at $1.41 each. LOL

I would suggest that you buy the bypass capacitors and resistors at the same time because shipping and handling will be more than the value of the stuff you are ordering.

 

[Miker1102]

Miker, I'm going to give you some deep-dive information on how to modify (improve) the sound of these speakers. Take a look at the post of June 30, 2017 in this thread:

https://community.classicspeakerpag...cs-a70-schematic/?tab=comments#comment-113609
A few things:
- I would not replace the gray Unicon capacitors that came stock with the A70. In my opinion, replacing the Unicon capacitors in these particular speakers with modern day NPE or polypropylene capacitors make thems sound worse and more fatiguing.

- The first thing I would try is installing these 0.01uF film and foil bypass capacitors across the existing Unicon capacitors:
https://www.parts-express.com/Dayton-Audio-DFFC-0.01-0.01uF-400V-By-Pass-Capacitor-027-450They are cheap...$0.99 each.

- If that still doesn't do the trick for you, add these 0.51 ohm resistors in series with the Unicon capacitors:
https://www.parts-express.com/Dayton-Audio-DNR-0.51-0.51-Ohm-10W-Precision-Audio-Grade-Res-004-.51They are brutally expensive at $1.41 each. LOL

I would suggest that you buy the bypass capacitors and resistors at the same time because shipping and handling will be more than the value of the stuff you are ordering.

Thank you for this. I am going to look at them this weekend and see about the replacements. I really appreciate the information very much because I was just thinking about using these as my rear for my set up. They do sound bright to me but I am also going to find a good reference sound system somewhere to give myself an idea as was suggested. Such excellent information here.