This is a detailed measurements of a modified Pioneer SP-BS22-LR speaker by @Dennis Murphy called Affordable Accuracy Monitor (AAM). He was kind enough to send me a sample. I let him explain the mods but basically the tweeter was replace with a higher quality one and a new modified crossover was put in place. Some padding was also added to the cabinet. He sold the modified pair for US $168 plus shipping. He no longer does this and has put his modifications in public domain.
The Pioneer BS22 was obviously designed to fit a ridiculously low manufacturing cost point of view especially considering the nice touches such as the curved cabinets and such. I liked the sample I tested in near-field. In this review I will be testing Dennis' speaker in far field.
Visually the speaker doesn't look much different:
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.
Spinorama Audio Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker can be used. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:
The modification is hard to see on this graph until we overlay the original on-axis response of the Pioneer on it:
We see that the response is much closer to the target flat on-axis response we look for good performing speakers.
While I don't usually put a lot of emphasis on vertical dispersion, I was surprised to see good bit of improvement there:
Early reflections are well behaved and smooth:
This results in very nice predicted in-room response:
Here is the before and after of the same:
I think the bigger deal here is the reduction of distortion in the tweeter so let's compare the two:
The crossover frequency (I think) is around 3 kHz. Notice how the distortion is basically brought to nothing on the modified version on the left above that. Whereas the original produces good bit of distortion especially around 5 kHz.
Comparing 86 and 96 dB SPL @ 1 meter on Dennis' speaker we see this tweeter is clean almost regardless of power:
It is the woofer that is going nuts as indicated before. There is so much this cheap little 4 inch woofer can produce.
Here are our directivity and waterfall measurements:
In mid-frequencies the dispersion is as wide as +- 100 degrees. Even at 20 kHz you have good bit of width to not having to lock your head a vice to listen.
Even vertical dispersion allows some room to be above or below the tweeter:
I did not try to optimize the waterfall. It is looking too good to be right!
Finally, here is the impedance graph:
Speaker Listening Tests
Regular readers of ASR know that per research, I listen to speaker in mono, placed to the left. Mono listening let's one judge the tonality of the speaker and its distortions much easier (a lot less perceptual masking). The performance of Affordable Accuracy Monitor in a word of superb! I could not believe how well it played through track after track in my reference list. Anyone who thinks mono listening can't sound good, should try listening to a well designed speaker. Alternatively, I suggest turning off one of the channels in your system and see how much you like the sound!
Sure, the bass driver craps out all of a sudden when you play loud with low frequency content. I adjusted the volume so that it was high enough in my huge space while avoiding its limit. I was then greeted with some of the best mid to high frequency presentation I had heard. Female vocals were to die for. Anything with a high frequency transients was produced with a clarity and beauty that was uncanny. They stood out not be cause they were over emphasized but because they were so clean and for a lack of a better word, "hi-fi."
I was surprised that even male vocals sounded wonderful. Play some Muddy Waters and you would have a smile on your face.
You could easily sense the dual personality of this speaker. Play something with just low notes and the sound was ordinary. Some piano tracks left me empty this way. But anything with modicum of full spectrum would bring ear to ear smile to my face.
I sat there for at least an hour going through my long playlist. I did not want to stop but stop I had to as it was past midnight and I was keeping my wife awake.
Note that my playlist was generated from listening to my library on my Revel Salon 2 speakers (around $23,000 a pair). This little speaker shows that if you follow the science with flat on-axis response and low distortion, you can emulate a lot of that experience with just $168. If the while industry did this, then we would have many good speakers that do justice to our content regardless of who designed them.
Conclusions
I am saddened that this little jewel is not produced anymore. I fully understand as I can't imagine buying these speakers and spending another $86 in parts and selling them for just $168. It would be definition of slavery in my opinion. I wish you all could sit here and listen to this speaker providing excellent enjoyment to well recorded music with just some limitations on bass and low-frequency loudness.
I am going to try to buy this sample from Dennis and hopefully one day use it for blind listening tests with our audiophile group.
Naturally, I highly recommended the Affordable Accuracy Monitor (AAM) if you can get your hands on it.
-----------
As always, questions, comments, recommendations, etc. are welcome.
The pink panthers wore through all their pink mask. I kept telling them to take them off before eating raw meat but they would not listen. My wife can make more but needs money for the fabric, filter material, etc. So would please donate a few dollars so that the panthers stay healthy using : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
The Pioneer BS22 was obviously designed to fit a ridiculously low manufacturing cost point of view especially considering the nice touches such as the curved cabinets and such. I liked the sample I tested in near-field. In this review I will be testing Dennis' speaker in far field.
Visually the speaker doesn't look much different:
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.
Spinorama Audio Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker can be used. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:
The modification is hard to see on this graph until we overlay the original on-axis response of the Pioneer on it:
We see that the response is much closer to the target flat on-axis response we look for good performing speakers.
While I don't usually put a lot of emphasis on vertical dispersion, I was surprised to see good bit of improvement there:
Early reflections are well behaved and smooth:
This results in very nice predicted in-room response:
Here is the before and after of the same:
I think the bigger deal here is the reduction of distortion in the tweeter so let's compare the two:
The crossover frequency (I think) is around 3 kHz. Notice how the distortion is basically brought to nothing on the modified version on the left above that. Whereas the original produces good bit of distortion especially around 5 kHz.
Comparing 86 and 96 dB SPL @ 1 meter on Dennis' speaker we see this tweeter is clean almost regardless of power:
It is the woofer that is going nuts as indicated before. There is so much this cheap little 4 inch woofer can produce.
Here are our directivity and waterfall measurements:
In mid-frequencies the dispersion is as wide as +- 100 degrees. Even at 20 kHz you have good bit of width to not having to lock your head a vice to listen.
Even vertical dispersion allows some room to be above or below the tweeter:
I did not try to optimize the waterfall. It is looking too good to be right!
Finally, here is the impedance graph:
Speaker Listening Tests
Regular readers of ASR know that per research, I listen to speaker in mono, placed to the left. Mono listening let's one judge the tonality of the speaker and its distortions much easier (a lot less perceptual masking). The performance of Affordable Accuracy Monitor in a word of superb! I could not believe how well it played through track after track in my reference list. Anyone who thinks mono listening can't sound good, should try listening to a well designed speaker. Alternatively, I suggest turning off one of the channels in your system and see how much you like the sound!
Sure, the bass driver craps out all of a sudden when you play loud with low frequency content. I adjusted the volume so that it was high enough in my huge space while avoiding its limit. I was then greeted with some of the best mid to high frequency presentation I had heard. Female vocals were to die for. Anything with a high frequency transients was produced with a clarity and beauty that was uncanny. They stood out not be cause they were over emphasized but because they were so clean and for a lack of a better word, "hi-fi."
I was surprised that even male vocals sounded wonderful. Play some Muddy Waters and you would have a smile on your face.
You could easily sense the dual personality of this speaker. Play something with just low notes and the sound was ordinary. Some piano tracks left me empty this way. But anything with modicum of full spectrum would bring ear to ear smile to my face.
I sat there for at least an hour going through my long playlist. I did not want to stop but stop I had to as it was past midnight and I was keeping my wife awake.
Note that my playlist was generated from listening to my library on my Revel Salon 2 speakers (around $23,000 a pair). This little speaker shows that if you follow the science with flat on-axis response and low distortion, you can emulate a lot of that experience with just $168. If the while industry did this, then we would have many good speakers that do justice to our content regardless of who designed them.
Conclusions
I am saddened that this little jewel is not produced anymore. I fully understand as I can't imagine buying these speakers and spending another $86 in parts and selling them for just $168. It would be definition of slavery in my opinion.
I wish you all could sit here and listen to this speaker providing excellent enjoyment to well recorded music with just some limitations on bass and low-frequency loudness.I am going to try to buy this sample from Dennis and hopefully one day use it for blind listening tests with our audiophile group.
Naturally, I highly recommended the Affordable Accuracy Monitor (AAM) if you can get your hands on it.
-----------
As always, questions, comments, recommendations, etc. are welcome.
The pink panthers wore through all their pink mask. I kept telling them to take them off before eating raw meat but they would not listen. My wife can make more but needs money for the fabric, filter material, etc. So would please donate a few dollars so that the panthers stay healthy using : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Last edited:
