Hello, new member here and hoping to get some feedback. I’ve got 4 Polk T15 speakers and they sound fairly awful. I’m wondering if it would be worthwhile to upgrade the drivers and cross over.
I’ve also got a pair of Morel mt120 tweeters that could be used, as well as likely all the electronics components lying around for crossover build.
My use case is home theatre but also listening to music although I can use another set for music if it was a compromise.
These will be the front main for my surround system which has a sub and they will be placed on a book shelf and unfortunately placed in a smallish cubicle. I will pull them forward and fill in the space on the sides to try to battle reflections in the cubicle.
Best. Are scenarios is if someone can suggest a woofer and crossover that would work well with the boxes and tweeters. I can pull the boxes apart and do measurements if needed. The woofers are 5.25”.
Thanks a bunch
I’ve also got a pair of Morel mt120 tweeters that could be used, as well as likely all the electronics components lying around for crossover build.
My use case is home theatre but also listening to music although I can use another set for music if it was a compromise.
These will be the front main for my surround system which has a sub and they will be placed on a book shelf and unfortunately placed in a smallish cubicle. I will pull them forward and fill in the space on the sides to try to battle reflections in the cubicle.
Best. Are scenarios is if someone can suggest a woofer and crossover that would work well with the boxes and tweeters. I can pull the boxes apart and do measurements if needed. The woofers are 5.25”.
Thanks a bunch
What are the dimensions of the box and how thick is the construction material of the box?
Depending on how much you want to spend, it might be better getting something like the Overnight Sensations
Overnight Sensations MT Speaker Kit Pair
or C-Notes
C-Note MT Bookshelf Speaker Kit Pair with Knock-Down Cabinets
These are both proven designs that are very well regarded.
Just something to think about.
Mike
Depending on how much you want to spend, it might be better getting something like the Overnight Sensations
Overnight Sensations MT Speaker Kit Pair
or C-Notes
C-Note MT Bookshelf Speaker Kit Pair with Knock-Down Cabinets
These are both proven designs that are very well regarded.
Just something to think about.
Mike
Average Joe Audiophile
Polk T15/R15 Review, Test, and Disassembly
Average Joe Audiophile: Polk T15/R15 Review, Test, and Disassembly
"The first budget speaker from a huge name brand that I’ve picked to disassemble and review. The T15 can regularly be found for in the $50-$60 at Best Buy which is what prompted my purchase and review. (From what I can gather the T15 and R15 are the exact same speaker, at the very least they seem to share the same tweeter. With the former being a Best Buy exclusive.)
Right off the bat it was by far the best constructed speaker I’ve seen in this price range. Thicker and a bit denser looking fiberboard than either the Dayton B653, Monoprice 8250 or the Sony B1000, the front face is nicely finished with what looks like a smooth plastic top surface, and most impressively it has at basic but real cross over (just a basic high pass and low pass filter for each driver). There is also some slight corner bracing going on. I didn’t weight them, but the T15 is heavier than the Dayton B652 and fares better on the knuckle wrap test.
So did all these seemingly clear and obvious bonuses translate into a better sounding speaker for the money?
For a quick answer; no they didn’t. At least not to my ears and at least not for music. I’ll get to theater use a bit later.
For the ABX comparisons I used the Dayton B652, generally considered one of the best $50 pair of bookshelf speakers out there, since the price points are the same I felt they made a good match to compare to. Starting from the bottom, or the bass one might say. The Polk T15 was adequate for a small bookshelf speaker; it actually had pretty decent extension into the 80hz range. However, as music moved out of the bass range and into everything else the speakers response became very peaky in room. Part of this is just the nature of my real world testing environment (I had some oddly flat outdoor measurements throughout the midrange and up into 3khz or so). The end result was something that sounded very much like many voices were being projected through a tube. Following this, is a huge drop off in treble response starting at 2.5khz and really lasting though the rest of the audio range. This was seen in both indoor listening environment testing and outdoor testing. The Polk T15 might as well be the bastard offspring of the Monoprice 8250 and the Sony B1000.
When it comes down to it, musically these speakers are just not good performers out of the box. So I decided to use these speakers as my first attempt to make my own EQ files using REW. After a few go arounds I feel like I actually got some decent sound out of them. They became much more musical, the tube like sound was gone and I started to enjoy them as much as I have some of the step up speakers I’ve been listening to. So they do have some potential if you take the time to take some room measurements and EQ as needed.
As a basic home theater speaker, I didn’t encounter any of the obvious issues I did with music. I watched plenty of TV and movies, with The Avengers being my final test. Now they didn’t blow my socks off or anything but they were a vast improvement form the Samsung F6300’s built in speakers. If you intend to us them in this application I think you could so worse. The Polk T15 would probably be a serviceable surround speaker for any of the other similar Polk products.
One thing I did take away as a whole, was that with a little bit of time spend working on an EQ file, these speakers really did become pretty pleasant. I don’t think it would be worthwhile to spend much time on room treatments or anything like that. But once EQ’d (a good) bit these were not bad. However out of the box I would still pick the Dayton B652 without question. "
Polk T15/R15 Review, Test, and Disassembly
Average Joe Audiophile: Polk T15/R15 Review, Test, and Disassembly
"The first budget speaker from a huge name brand that I’ve picked to disassemble and review. The T15 can regularly be found for in the $50-$60 at Best Buy which is what prompted my purchase and review. (From what I can gather the T15 and R15 are the exact same speaker, at the very least they seem to share the same tweeter. With the former being a Best Buy exclusive.)
Right off the bat it was by far the best constructed speaker I’ve seen in this price range. Thicker and a bit denser looking fiberboard than either the Dayton B653, Monoprice 8250 or the Sony B1000, the front face is nicely finished with what looks like a smooth plastic top surface, and most impressively it has at basic but real cross over (just a basic high pass and low pass filter for each driver). There is also some slight corner bracing going on. I didn’t weight them, but the T15 is heavier than the Dayton B652 and fares better on the knuckle wrap test.
So did all these seemingly clear and obvious bonuses translate into a better sounding speaker for the money?
For a quick answer; no they didn’t. At least not to my ears and at least not for music. I’ll get to theater use a bit later.
For the ABX comparisons I used the Dayton B652, generally considered one of the best $50 pair of bookshelf speakers out there, since the price points are the same I felt they made a good match to compare to. Starting from the bottom, or the bass one might say. The Polk T15 was adequate for a small bookshelf speaker; it actually had pretty decent extension into the 80hz range. However, as music moved out of the bass range and into everything else the speakers response became very peaky in room. Part of this is just the nature of my real world testing environment (I had some oddly flat outdoor measurements throughout the midrange and up into 3khz or so). The end result was something that sounded very much like many voices were being projected through a tube. Following this, is a huge drop off in treble response starting at 2.5khz and really lasting though the rest of the audio range. This was seen in both indoor listening environment testing and outdoor testing. The Polk T15 might as well be the bastard offspring of the Monoprice 8250 and the Sony B1000.
When it comes down to it, musically these speakers are just not good performers out of the box. So I decided to use these speakers as my first attempt to make my own EQ files using REW. After a few go arounds I feel like I actually got some decent sound out of them. They became much more musical, the tube like sound was gone and I started to enjoy them as much as I have some of the step up speakers I’ve been listening to. So they do have some potential if you take the time to take some room measurements and EQ as needed.
As a basic home theater speaker, I didn’t encounter any of the obvious issues I did with music. I watched plenty of TV and movies, with The Avengers being my final test. Now they didn’t blow my socks off or anything but they were a vast improvement form the Samsung F6300’s built in speakers. If you intend to us them in this application I think you could so worse. The Polk T15 would probably be a serviceable surround speaker for any of the other similar Polk products.
One thing I did take away as a whole, was that with a little bit of time spend working on an EQ file, these speakers really did become pretty pleasant. I don’t think it would be worthwhile to spend much time on room treatments or anything like that. But once EQ’d (a good) bit these were not bad. However out of the box I would still pick the Dayton B652 without question. "
I have measure the outside of the box at 11"x6.5"x6.5".
I realize it would likely be easier to just build one of the kits.
There is the wife factor though... I just bought a bunch of new gear.. TV, AVR, etc.. might not be a good thing to have a new set of speakers delivered!
Also I do have the option to bi-amp these speakers. My receiver is the Integra DXR2.0 which allows bi-amping of the fronts only. It does not appear there is very fine control over the crossovers but it could be an option.
Is the MT120 considered a good tweeter for this application? It would be nice to put them to use. They have been sitting in the garage for a year or so with nothing planned.
Anyway all comments are appreciated. I am very much into doing some work to figure this out so not entirely just looking for an info handout if it is more complicated than a simple woofer recommendation would account for. A point in the right direction would probably do the trick.. or convince me its a lost cause.
I realize it would likely be easier to just build one of the kits.
There is the wife factor though... I just bought a bunch of new gear.. TV, AVR, etc.. might not be a good thing to have a new set of speakers delivered!
Also I do have the option to bi-amp these speakers. My receiver is the Integra DXR2.0 which allows bi-amping of the fronts only. It does not appear there is very fine control over the crossovers but it could be an option.
Is the MT120 considered a good tweeter for this application? It would be nice to put them to use. They have been sitting in the garage for a year or so with nothing planned.
Anyway all comments are appreciated. I am very much into doing some work to figure this out so not entirely just looking for an info handout if it is more complicated than a simple woofer recommendation would account for. A point in the right direction would probably do the trick.. or convince me its a lost cause.
I used to have a pair of R15's, so if they are the same as the T15 as was suggested, I would recommend designing a new crossover for the speakers you have. As I recall from the analysis I did of my R15's, the tweeters are pretty decent and measure pretty flat, if I recall. The woofer has an a resonance around 1.25kHz that adds some coloration and I highly suspect that it's a major contributor to the "voices sounding like they're coming through a tube" described in that review, but I can't say how objectionable it sounds to you.
The big issue with them is the first order crossover at + 4.5kHz, in their stock configuration, they're at their best with the listening axis about 20 degrees below the tweeter, that's about where the drivers sum properly. Redesigning the crossover should make those speakers sound much nicer.
The big issue with them is the first order crossover at + 4.5kHz, in their stock configuration, they're at their best with the listening axis about 20 degrees below the tweeter, that's about where the drivers sum properly. Redesigning the crossover should make those speakers sound much nicer.
It would be worth the effort plus education to design a superior crossover with modest cost L-R-C parts for one pair of T50 drivers and listen before you make a larger investment.
=========
1) Open up a pair of T50 speakers and confirm that the tweeter crossover is a series connected single electrolitic capacitor..... and the woofer LC crossover is a series connected inductor plus electrolitic capacitor to ground.
2) BIG GOOGLE search for alternative T50 crossovers already built by smart people.
NO LUCK.... THEN
3) Study how to make basic T/S measurements of each driver. If you have a mic you can also learn how to make SPL measurements.
4) With these measurements.... Ask diyAudio community to design a good crossover. probably 3rd order C-L-C on the tweeter and 2nd order LC on the woofer. A series resistor in front of the C-L-C tweeter crossover will allow SPL balance with the woofer.
Attachments
Interesting information. I am definitely hearing a midrange resonance but just going by ear I thought it was around 2khz. Okay I like where this is going. I’ll open one up and see if I can indentify the cross over components.
My Bad 
The woofer crossover is just a series inductor. Can you measure the inductance on this part? The DC resistance of tweeter and woofer? There are several tutorials on measuring T/S parameters and SPL/freq. Download free sine sweep generator + voltmeter + known mass(coin).
Design a good crossover, like C-L-C on the tweeter and LC on the woofer. A series resistor in front of the C-L-C tweeter crossover will allow SPL balance with the woofer.
The woofer crossover is just a series inductor. Can you measure the inductance on this part? The DC resistance of tweeter and woofer? There are several tutorials on measuring T/S parameters and SPL/freq. Download free sine sweep generator + voltmeter + known mass(coin).
Design a good crossover, like C-L-C on the tweeter and LC on the woofer. A series resistor in front of the C-L-C tweeter crossover will allow SPL balance with the woofer.
Okay, can I just proceed with @aslepekis measurements or Better to do my own? I have a multimeter, oscope, signal generator, recording mics, etc, but if this is already the info needed would rather save some time.
I’ve read a bit about crossover design. There is definitely a lot going on. One question I have is this.. what I’ve learned working with music and recording is that things that should sound good don’t always, and vice versa. What I’m getting at is do any of you find it is more productive to do a general design and then just trial and error component values to find the sweet spot?
I’ve read a bit about crossover design. There is definitely a lot going on. One question I have is this.. what I’ve learned working with music and recording is that things that should sound good don’t always, and vice versa. What I’m getting at is do any of you find it is more productive to do a general design and then just trial and error component values to find the sweet spot?
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