germanium
Headphoneus Supremus
I purchased a set of JBL LSR305 monitors after comparing them with several others at guitar center. Things that I liked about them in the store was their smooth & extended bass for there size & solid dynamics in the bass especially for their size. They sounded like much bigger speaker than they were. It sounded like they had 6-7inch bass drivers instead of 5 inch. Even the bass extension was suggestive of a larger driver that was not far off of what most 8 inch drivers are capable of. Most 5inch drivers start to roll off in the mid to upper 50Hz range these go down to 43 Hz but die very quickly afterwards. Most 8 inch monitor speakers only go down into the upper 30HZ range as in for example the LSR308's only go down to 37Hz.
While these may be analog input speakers but internally they do all processing & amplification digitally. The crossover & any driver EQ is done in the digital domain. I looked up the major chips that I found on the board.
There is an STA350 capable of up to 50 watts per channel in stereo mode in to a 6 ohm load. This chip handles all the crossover & EQ functions as well. It also can do anti-clipping limiting as well as compression though this last capability is not used here only the anti-clipping limiter is used.
http://www.st.com/web/catalog/sense_power/FM125/SC1756/PF251568?sc=internet/imag_video/product/251568.jsp
There is a Cirrus Logic 5341 ADC on board as well which handles the analog to digital conversion.
http://www.cirrus.com/en/products/cs5341-42.html
There is also an STM8S0 chip that is a BIOS chip that has a serial interface for storing the parameters used by the STA350. This chip also contains a small 16MHz CPU.
http://www.st.com/web/catalog/mmc/FM141/SC1244/SS1010/LN2/PF251792
The woofer cone is made of a plasticized paper with a soft plastic dust cap & a rubber surround, The magnet structure is good size for this driver & contains a secondary magnet to contain stray magnetic field so you can use the close to older style CRT monitor displays.
The tweeter is a 1 inch soft dome made of tightly woven fabric & mounted in a horn like wave guide that controls dispersion. The magnet structure is quite small but seems quite powerful so the must be using neodymium magnets.
The output power in this case is about 50 watts to the woofer & about 30-35 watts to the tweeter giving a total of 80-85 watts. Most review sites list the power to each driver as 41 watts but this is definitely not the case given the impedance characteristics of the driver which are not the same. The woofer is clearly a 6 ohm unit & the tweeter appears to be a 10 ohm unit.
Well the real question is how do they sound in my own home. In a word astoundingly good, far beyond what I imagined a small speaker is capable of doing. The bass is robust & smooth & lacking any kind of noticeable distortion a any kind of reasonable volume & even when pushed to somewhat more than reasonable volume. The crossover & EQ are impeccably handled resulting in a very smooth sound signature. The tweeter is some what larger than some tweeter drivers used on speakers that have 5 inch woofers, such as the BX5's, that combined with the horn like wave guide allows the tweeter to handle a lower frequency cross over than most tweeters can used with 5 inch woofers, this improves the detail near the crossover quite a lot. The body you hear from the tweeter matches that of the woofer at the cross over frequency very well. dispersion is also well matched between the 2 drivers.
These speakers are said to have a broader sweet spot for listening off axis. In my situation they show excellent frequency response across a broad listening area. Image still moves though when you move closer to one speaker than the other which is to be expected.
Depth of soundstage in recordings is quite good, some of the best I have heard. The amount of detail within that soundstage is also excellent, far beyond what one would expect to have from such inexpensive speakers & it's not a hyped detail gotten through hyped up treble. List price of these is 149 dollars for each speaker, basically 300 dollars for a stereo pair
I have yet to play some music that contain places where there is intentional imaging beyond the outer edges of the speakers but will provide that info in a later update.
Update; The speakers do image beyond outer edges of the speakers well indeed.
The only fly in the ointment with the speaker is really one to be expected given the size of the bass driver & part of this is due to the steep subsonic filter. That is on 90-95% of the music is not a problem but on 5-10% of the music the bass drops like a rock below 43Hz like as in nothing there after being so strong up to that point. Consequently you will need a sub if you have any music at all that goes lower than 43 Hz as the effect can be somewhat jarring if there are lot of notes near that cutoff frequency, otherwise you will get strong notes then nothing & then right back to loud bass notes with extreme suddenness. A subwoofer can fix this though you need one that can crossover below 50Hz. Most can not do so at least not from the factory.
Speakers are very quiet, Only a very faint hiss from the tweeter on both channels but I have to put my ear right up to the tweeter to hear it.
Here are some pictures of the JBL LSR305's inside & out.
This is the main amp board. As you see there only is a relatively small chip near the speaker outputs though it is the largest chip on the board. This chip does everything except the analog to digital conversion & can provide up to 50 watts per channel in stereo into a 6 ohm load. If used in mono mode it can provide up to 90 watts into a 3 ohm load. It even does the crossover digitally & any EQ as well.
Here you can see the paper like backing of the bass driver.
Here you can see how large the magnets are
The back side of the front panel with drivers.
The panel showing the adjustments available.
This is the JBL's in my computer sound setup.
While these may be analog input speakers but internally they do all processing & amplification digitally. The crossover & any driver EQ is done in the digital domain. I looked up the major chips that I found on the board.
There is an STA350 capable of up to 50 watts per channel in stereo mode in to a 6 ohm load. This chip handles all the crossover & EQ functions as well. It also can do anti-clipping limiting as well as compression though this last capability is not used here only the anti-clipping limiter is used.
http://www.st.com/web/catalog/sense_power/FM125/SC1756/PF251568?sc=internet/imag_video/product/251568.jsp
There is a Cirrus Logic 5341 ADC on board as well which handles the analog to digital conversion.
http://www.cirrus.com/en/products/cs5341-42.html
There is also an STM8S0 chip that is a BIOS chip that has a serial interface for storing the parameters used by the STA350. This chip also contains a small 16MHz CPU.
http://www.st.com/web/catalog/mmc/FM141/SC1244/SS1010/LN2/PF251792
The woofer cone is made of a plasticized paper with a soft plastic dust cap & a rubber surround, The magnet structure is good size for this driver & contains a secondary magnet to contain stray magnetic field so you can use the close to older style CRT monitor displays.
The tweeter is a 1 inch soft dome made of tightly woven fabric & mounted in a horn like wave guide that controls dispersion. The magnet structure is quite small but seems quite powerful so the must be using neodymium magnets.
The output power in this case is about 50 watts to the woofer & about 30-35 watts to the tweeter giving a total of 80-85 watts. Most review sites list the power to each driver as 41 watts but this is definitely not the case given the impedance characteristics of the driver which are not the same. The woofer is clearly a 6 ohm unit & the tweeter appears to be a 10 ohm unit.
Well the real question is how do they sound in my own home. In a word astoundingly good, far beyond what I imagined a small speaker is capable of doing. The bass is robust & smooth & lacking any kind of noticeable distortion a any kind of reasonable volume & even when pushed to somewhat more than reasonable volume. The crossover & EQ are impeccably handled resulting in a very smooth sound signature. The tweeter is some what larger than some tweeter drivers used on speakers that have 5 inch woofers, such as the BX5's, that combined with the horn like wave guide allows the tweeter to handle a lower frequency cross over than most tweeters can used with 5 inch woofers, this improves the detail near the crossover quite a lot. The body you hear from the tweeter matches that of the woofer at the cross over frequency very well. dispersion is also well matched between the 2 drivers.
These speakers are said to have a broader sweet spot for listening off axis. In my situation they show excellent frequency response across a broad listening area. Image still moves though when you move closer to one speaker than the other which is to be expected.
Depth of soundstage in recordings is quite good, some of the best I have heard. The amount of detail within that soundstage is also excellent, far beyond what one would expect to have from such inexpensive speakers & it's not a hyped detail gotten through hyped up treble. List price of these is 149 dollars for each speaker, basically 300 dollars for a stereo pair
I have yet to play some music that contain places where there is intentional imaging beyond the outer edges of the speakers but will provide that info in a later update.
Update; The speakers do image beyond outer edges of the speakers well indeed.
The only fly in the ointment with the speaker is really one to be expected given the size of the bass driver & part of this is due to the steep subsonic filter. That is on 90-95% of the music is not a problem but on 5-10% of the music the bass drops like a rock below 43Hz like as in nothing there after being so strong up to that point. Consequently you will need a sub if you have any music at all that goes lower than 43 Hz as the effect can be somewhat jarring if there are lot of notes near that cutoff frequency, otherwise you will get strong notes then nothing & then right back to loud bass notes with extreme suddenness. A subwoofer can fix this though you need one that can crossover below 50Hz. Most can not do so at least not from the factory.
Speakers are very quiet, Only a very faint hiss from the tweeter on both channels but I have to put my ear right up to the tweeter to hear it.
Here are some pictures of the JBL LSR305's inside & out.
This is the main amp board. As you see there only is a relatively small chip near the speaker outputs though it is the largest chip on the board. This chip does everything except the analog to digital conversion & can provide up to 50 watts per channel in stereo into a 6 ohm load. If used in mono mode it can provide up to 90 watts into a 3 ohm load. It even does the crossover digitally & any EQ as well.
Here you can see the paper like backing of the bass driver.
Here you can see how large the magnets are
The back side of the front panel with drivers.
The panel showing the adjustments available.
This is the JBL's in my computer sound setup.