This is a review and detailed measurements of the Boston Acoustics A 25 bookshelf speaker. I purchased these a while back at a discount. Seems that they were originally released back in 2011 for US $300 a pair. At the time I purchased them the price had dropped to US $180 a pair. There were taxes and shipping costs added to the price. After discount, my net cost was $155.
The fit and finish of the speaker belies its very low price:
As you see there is some kind of faux leather surrounding the front baffle. Same is used underneath which is useful in keeping the speaker planted. Sides are gloss which gives the speaker fair bit of class. The cabinet feels dense, solid and heavy for its size.
Back panel shows nice provisions for hanging the unit and same leatherette finish:
Hard to imagine this speaker is being sold for so little. Externally anyways....
Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.
I performed over 1000 measurement which resulted in error rate of more or less 1%.
Temperature was 58 degrees F. Measurement location is at sea level so you compute the pressure.
Measurements are compliant with latest speaker research into what can predict the speaker preference and is standardized in CEA/CTA-2034 ANSI specifications. Likewise listening tests are performed per research that shows mono listening is much more revealing of differences between speakers than stereo or multichannel.
Reference axis was the tweeter center.
Boston A 25 Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker is and how it can be used in a room. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:
I must say at first I thought this was rather chewed up. But if we ignore the upper frequencies above 10 kHz, the rest is not too bad. We have a bit of peaking around 900 Hz. And a dip around 3 kHz.
Directivity is actually decent which means we can a) EQ the response and b) response will not be too room dependent.
The issue at 900 Hz becomes obvious when we look at the nearfield measurements of each sound radiating element:
The port becomes a bit crazy above its intended response and generates a couple of peaks. In addition, we see the tweeter having rather non-flat response.
The tweeter seems to have a steeper roll off than the woofer causing the dip in the crossover region.
Back to our spinorama, here is our early window reflections:
Like most speakers, floor reflections have a large dip and is best avoided with a thick carpet (which my listening room has).
Predicted in-room response is:
Impedance curve shows the resonances we have discussed:
Horizontal beam width is actually quite decent:
As is contour of the same:
They have made an attempt to narrow the gap between the woofer and tweeter and it shows in better vertical response:
Edit: forgot the distortion graphs:
Boston A25 Listening Tests
I placed the A25 in my usual far-field setting. First impression was positive. Certainly better than casual glance of the spin data. Some touch up EQ nicely lifted the response:
I tried to lift the dip but it subjectively made the speaker sound bright on some tracks so I took it off. As I noted earlier, I have a thick carpet so the predicted in-room response for me is better than what I showed.
The first filter is to get rid of distortion. It took away a bit of bass so you may want to play with it. The dip to get rid of the resonance was effective of making the sound lighter and vocals to stand out a bit more which I liked. The final shelving was to get rid of occasional brightness depending on track. I hate the fact that we have no production standards so sometimes seems impossible to actually tailor the overall "target curve."
Once there, the sound was quite nice. I listened for good 30 minutes and track after track sounded beautiful. Here is an example from Gait Kelin Kromhof:
Sorry, there is no youtube track for it. It is superb music that is very well recorded and it sounded great on the A25.
Dynamics were superb here and I could detect no sign of distortion at very high volumes. That said, if you listen to the port in the back, it sure sounded distorted and badly so. My back wall is from far from the speaker so I could not hear it from the front. If your situation is different, then the experience may not be as rewarding as it was for me.
Conclusions
The fit and finish of the Boston Acoustics A25 matches a speaker north of $800 a pair. It is hard to imagine how they pulled it off at such a low price. Objectively, the response is not ideal but somehow the mistakes are not that big with respect to audibility and easily corrected. While the speaker seems discontinued, searching for good prices as I did on clearance is an excellent idea. You will certainly get a speaker with far more power capability and better tonality than most budget speakers.
I am going to put the Boston A 25 on my recommended list.
------------
As always, questions, comments, recommendations, etc. are welcome.
Could no longer walk in our garage. So took out of main barbeque grill and smoker and put them on the deck. Now I have more space and ability to cook in winter just as well! Why do I say this? Because it sure would be good to have some money sent my way for meet to smoke! Have to eat good in winter or depression can set in with the gloomy days we have!
Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
The fit and finish of the speaker belies its very low price:
As you see there is some kind of faux leather surrounding the front baffle. Same is used underneath which is useful in keeping the speaker planted. Sides are gloss which gives the speaker fair bit of class. The cabinet feels dense, solid and heavy for its size.
Back panel shows nice provisions for hanging the unit and same leatherette finish:
Hard to imagine this speaker is being sold for so little. Externally anyways....
Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.
I performed over 1000 measurement which resulted in error rate of more or less 1%.
Temperature was 58 degrees F. Measurement location is at sea level so you compute the pressure.
Measurements are compliant with latest speaker research into what can predict the speaker preference and is standardized in CEA/CTA-2034 ANSI specifications. Likewise listening tests are performed per research that shows mono listening is much more revealing of differences between speakers than stereo or multichannel.
Reference axis was the tweeter center.
Boston A 25 Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker is and how it can be used in a room. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:
I must say at first I thought this was rather chewed up. But if we ignore the upper frequencies above 10 kHz, the rest is not too bad. We have a bit of peaking around 900 Hz. And a dip around 3 kHz.
Directivity is actually decent which means we can a) EQ the response and b) response will not be too room dependent.
The issue at 900 Hz becomes obvious when we look at the nearfield measurements of each sound radiating element:
The port becomes a bit crazy above its intended response and generates a couple of peaks. In addition, we see the tweeter having rather non-flat response.
The tweeter seems to have a steeper roll off than the woofer causing the dip in the crossover region.
Back to our spinorama, here is our early window reflections:
Like most speakers, floor reflections have a large dip and is best avoided with a thick carpet (which my listening room has).
Predicted in-room response is:
Impedance curve shows the resonances we have discussed:
Horizontal beam width is actually quite decent:
As is contour of the same:
They have made an attempt to narrow the gap between the woofer and tweeter and it shows in better vertical response:
Edit: forgot the distortion graphs:
Boston A25 Listening Tests
I placed the A25 in my usual far-field setting. First impression was positive. Certainly better than casual glance of the spin data. Some touch up EQ nicely lifted the response:
I tried to lift the dip but it subjectively made the speaker sound bright on some tracks so I took it off. As I noted earlier, I have a thick carpet so the predicted in-room response for me is better than what I showed.
The first filter is to get rid of distortion. It took away a bit of bass so you may want to play with it. The dip to get rid of the resonance was effective of making the sound lighter and vocals to stand out a bit more which I liked. The final shelving was to get rid of occasional brightness depending on track. I hate the fact that we have no production standards so sometimes seems impossible to actually tailor the overall "target curve."
Once there, the sound was quite nice. I listened for good 30 minutes and track after track sounded beautiful. Here is an example from Gait Kelin Kromhof:
Sorry, there is no youtube track for it. It is superb music that is very well recorded and it sounded great on the A25.
Dynamics were superb here and I could detect no sign of distortion at very high volumes. That said, if you listen to the port in the back, it sure sounded distorted and badly so. My back wall is from far from the speaker so I could not hear it from the front. If your situation is different, then the experience may not be as rewarding as it was for me.
Conclusions
The fit and finish of the Boston Acoustics A25 matches a speaker north of $800 a pair. It is hard to imagine how they pulled it off at such a low price. Objectively, the response is not ideal but somehow the mistakes are not that big with respect to audibility and easily corrected. While the speaker seems discontinued, searching for good prices as I did on clearance is an excellent idea. You will certainly get a speaker with far more power capability and better tonality than most budget speakers.
I am going to put the Boston A 25 on my recommended list.
------------
As always, questions, comments, recommendations, etc. are welcome.
Could no longer walk in our garage. So took out of main barbeque grill and smoker and put them on the deck. Now I have more space and ability to cook in winter just as well! Why do I say this? Because it sure would be good to have some money sent my way for meet to smoke! Have to eat good in winter or depression can set in with the gloomy days we have!
Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
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