[ryant]

There are two thoughts I have on why the difference could be relatively insignificant on a FR graph. The immediate thought is that the world of audio is pretty tricky because out mind influences what we hear greatly. Did you do any actual true blind testing against his stock LR305 speakers? Something where you had them set side by side where they couldn't be seen by you and had the source material played through one and then immediately had it switch to the other all while being at the exact same volume? When I was building speakers I would try a lot of different things and I thought I was hearing huge improvements but when I actually put them to the test it turns out it wasn't so significant. I would have both speakers side by side and hook them up to a stereo amp. I would have my source material in mono and have a friend A/B the speakers while not telling me which was which. Often times I could hear a small difference but it almost always was much smaller than I initially remembered. Without true blind testing, it's possible the differences between stock and modified isn't quite as drastic if you listened to two pairs with all things being equal and not knowing which was which. 
 
That said, it's also entirely possible that they DO sound different. The environment they are measured in and how the process was done plays a huge role but in the end, a simple FR graph really isn't all that useful in determining the way a speaker sounds. It can be great to see how a speakers timbre is and whether there is huge spikes in the trebble or big bass roll offs. But if you didn't significantly alter the response (volume of the tweeter, woofer, etc) then It's likely to not show on an FR graph. Something along the lines of a waterfall graph is probably more useful since it can help you figure out many other trouble spots in a speaker or headphones response. I'm certainly not well versed in it but I know the FR graph alone is fairly limited.

 

[germanium]

Unfortunately neither of us have the facilities to do blind testing of any kind. My girl friend who is no audiophile easily heard & described the difference that she heard & they agreed with what I was hearing that they definately sounded a lot more like you were listening to a live event than to speakers & she want me to mod hers as well which I will be doing this weekend.

The volumes were untouched between listening & the settings on the speakers were exactly the same. The volume knob on the speakers are detented facilitating easily matching the settings between the speakers. As the only changes that were done was to the capacitors, no resistors were changed, matching the settings would serve the desired purpose. Any increase in volume would have indicated a reduction of signal loss from the original capacitors compared to the new ones. I think this is actually a valid test.

Just a note here is that increasing volume does not always make things sound better at least not to my ears. The fact the the speakers do sound more lively flies in the face of my previous experience where increasing volume up to a certain point makes speaker sound more warm & full & not necessarily more detailed, here the warmth & fullness are not increased over stock but neither is it lost at matched volume settings but there is definitely more energy & detail to the sound. Increasing volume beyond a certain point will cause the muscles in the ear to tighten , when that happens you start to lose warmth to the sound & everything starts sounding compressed. this did not happen in our listening tests. volume remained well within the ears comfort range before the ear starts trying to protect itself

The sound is also more forward making some recordings sound like they have less depth to the soundstage but other recordings that were recorded with capturing soundstage depth in mind have a positively huge soundstage. It all depends on the recording really.

 

[serman005]

Unfortunately neither of us have the facilities to do blind testing of any kind. My girl friend who is no audiophile easily heard & described the difference that she heard & they agreed with what I was hearing that they definately sounded a lot more like you were listening to a live event than to speakers & she want me to mod hers as well which I will be doing this weekend.

The volumes were untouched between listening & the settings on the speakers were exactly the same. The volume knob on the speakers are detented facilitating easily matching the settings between the speakers. As the only changes that were done was to the capacitors, no resistors were changed, matching the settings would serve the desired purpose. Any increase in volume would have indicated a reduction of signal loss from the original capacitors compared to the new ones. I think this is actually a valid test.

Just a note here is that increasing volume does not always make things sound better at least not to my ears. The fact the the speakers do sound more lively flies in the face of my previous experience where increasing volume up to a certain point makes speaker sound more warm & full & not necessarily more detailed, here the warmth & fullness are not increased over stock but neither is it lost at matched volume settings but there is definitely more energy & detail to the sound. Increasing volume beyond a certain point will cause the muscles in the ear to tighten , when that happens you start to lose warmth to the sound & everything starts sounding compressed. this did not happen in our listening tests. volume remained well within the ears comfort range before the ear starts trying to protect itself

The sound is also more forward making some recordings sound like they have less depth to the soundstage but other recordings that were recorded with capturing soundstage depth in mind have a positively huge soundstage. It all depends on the recording really.

This is interesting.

 

[Skooter]

Germanium,
 
There are some interesting comments on the LSR305 by a guy called "no audiophile." As you have modded your speakers, this guy makes two interesting observations:
 
http://noaudiophile.com/JBL_LSR305/
 
 
1. More expensive JBLs fill the inside/back of the waveguide with some type of resin. The inexpensive 305 is just the plastic.
 
 
- Who knows what filler JBL used. Untested epoxy is a bit risky as it might kill the waveguide's plastic. Consider some neutral resin perhaps
- However, the 305's built in DSL might compensate (somewhat) for the lack of resin already
- Any resin you add will change the volume of the cabinet slightly
 
2. There is a spike at 1350Hz on his model which he could not isolate. He speculated it could be the cheap cabinet resonating, driver issues, the amp board physically ringing, or edge defraction.
 
- Consider reinforcing the box, even just temporarily just to see if that makes a difference
- Maybe put some neutral silicone on the pcb board to prevent ringing
- I also tend to stuff my speaker with additional polyfill for different reasons but if it stops this resonating I think it would be luck more than anything
 
Take a look at the article and perhaps his observations can help you further improve the LSR305...
 
edit: this is the noaudiophile guy's effort to put resin into the back of the waveguide of the 308: http://noaudiophile.com/JBL_LSR308/

 

[germanium]

bump

 

[derpaudio]

Great review! Been looking for some really great monitoring speakers in the budget range and now I'm down to two options: the LSR305 and the Rokit 5. I'd been  leaning towards the LSR305 studio speakers coz apparently the Rokit 5 overemphasize the low ends. But recently I just read that the LSR305's midrange can be a little weak compared to other monitoring speakers. Plus this site http://www.studio-speakers.com/bestmonitoringspeakersreview/ considers the Rokit 5 as the best in the budget range so now I'm torn again. So is it true that the LSR305's midrange is weaker than other studio speakers?? Should I just get the Rokit 5 instead??

 

[germanium]

  Great review! Been looking for some really great monitoring speakers in the budget range and now I'm down to two options: the LSR305 and the Rokit 5. I'd been  leaning towards the LSR305 studio speakers coz apparently the Rokit 5 overemphasize the low ends. But recently I just read that the LSR305's midrange can be a little weak compared to other monitoring speakers. Plus this site http://www.studio-speakers.com/bestmonitoringspeakersreview/ considers the Rokit 5 as the best in the budget range so now I'm torn again. So is it true that the LSR305's midrange is weaker than other studio speakers?? Should I just get the Rokit 5 instead??

I would not consider the mids to be lacking compared to any speaker in its price point. However stock there is some issues with the mids due to the poor quality electrolytic coupling capacitors in the input circuit. replacing these capacitors with high quality metallized film capacitors does wonders to address those issues bringing these speakers up to giant killer status without much extra monetary outlay. These low quality coupling capacitors are used in virtually all low priced equipment so it is practically impossible to get around those issues with low priced audio gear. I found these speakers to be the most neutral out of the box speakers & they become even more neutral with my mods. This was confirmed with actual instrumented testing.

 

[derpaudio]

 
I would not consider the mids to be lacking compared to any speaker in its price point. However stock there is some issues with the mids due to the poor quality electrolytic coupling capacitors in the input circuit. replacing these capacitors with high quality metallized film capacitors does wonders to address those issues bringing these speakers up to giant killer status without much extra monetary outlay. These low quality coupling capacitors are used in virtually all low priced equipment so it is practically impossible to get around those issues with low priced audio gear. I found these speakers to be the most neutral out of the box speakers & they become even more neutral with my mods. This was confirmed with actual instrumented testing.

When all you can afford is budget speakers you don't really have a choice, right? But thanks. I'm definitely getting the LSR305 now.

 

[samuelli16]

These are incredible studio monitors. 
 
I've used them for over a year for my home studio and I love them. The midrange is amazing, although the only flaw is that below 43Hz the bass gets muddy.

 

[TimHKG]

 
I would not consider the mids to be lacking compared to any speaker in its price point. However stock there is some issues with the mids due to the poor quality electrolytic coupling capacitors in the input circuit. replacing these capacitors with high quality metallized film capacitors does wonders to address those issues bringing these speakers up to giant killer status without much extra monetary outlay. These low quality coupling capacitors are used in virtually all low priced equipment so it is practically impossible to get around those issues with low priced audio gear. I found these speakers to be the most neutral out of the box speakers & they become even more neutral with my mods. This was confirmed with actual instrumented testing.

First of all, I'd like to say thanks to your detailed elaborations of this monitoring speakers!
 
I do have a pair of LSR305, would you please circle or point out which capacitors on the photo of the board you've had replaced with metalized film capacitors? Thanks in advance!

 

[GCKelloch]

Hi all, and thanks to Germanium for posting all this useful info. I just got a pair of LSR305 myself, and I find the caps mod intriguing. I am also considering filling the baffle and possibly coating the rear plate and port with something like Titebond 'Fast Set Polyurethane Construction Adhesive'. Of course, none of that will make any difference if the Rs of each component is already above the woofer output freq. I'd think ~3.5kHz would be high enough to eliminate any audible contribution. My guess is some of the baffle area and the rear plate Rs are well below 3.5kHz. Changing caps will void the warranty anyway, and both mods may add up to a substantial clarity improvement.

I also wanted to point out that changing the neg feedback cap values changes the neg feedback bleed cutoff freq for each amp. I'd assume that the 12uF cap eliminates a lot of neg feedback on the bass amp in that the bleed cutoff would be nearly one decade lower. You may have eliminated some resonances/distortions with better input coupling caps, but you also allowed the amps to operate more "wildly", so there will be increased volume and some resonance and harmonic distortion in the non feedback range at higher volumes. That's probably responsible for the increased bass warmth and high harmonics. It's just the Op Amp generated harmonics added to the signal. Otherwise, full range neg feedback would cause some overall compression b4 clipping. Which effect you prefer is personal taste, but I'd just assume stick with the original values for an overall cleaner and more balanced response. Since the audio signal through those caps is in fact bled to ground, is there really an improvement from better caps there?

When you get a chance, I would also like to know where all the caps to be changed are located, and the C and V values and possibly a brand to order (just so I don't have to open the panels again b4 doing the work), and if there are any other audio path caps worth replacing?

 

[TimHKG]

So, anyone can comment on, by changing which capacitors or components on the board, will get the most obvious improvement of the sound? Thanks in advance!

 

[GCKelloch]

Thanks for doing that Tim. Aiken Amplification recommends polypropylene film caps for best temp stability and clarity, so I might use those if I can find the right values. If I knew which were the input coupling caps, I might just change them. The 100uF caps I can find of these types are very expensive. Again, I would not want to alter the neg feedback, therefore the spectral balance, with different cap values.

In the meantime, I figured the speaker wire magnet chokes might cause some electrodynamic interference around the xover point, so I tied one over to a ground lead a few inches away. I suppose it is possible for signal cancellations and/or reinforcements to occur via magnetic signal transfer if two wires from each amp are right next to each other without the opposite polar wire from each at the exact same distances.

 

[TimHKG]

To be frank, in my opinion, besides the improvement of the sound quality, to concentrate on how to eliminate the hiss noise coming from the tweeter(though it's inevitable, always exist in reality, and especially serious in LSR305's such cheap & low D-class amplifier board), is a more important task at this moment if I'm going to modify them. In my case, it's audible when turning up the volume to 7 and getting quite louder from then on..., perhaps not that serious when comparing to other owners'?

By doing such as...enhancing shielding of the transformer? Or replacing components with low-noise and high-quality ones? Or by inaugurating on...etc., will it be solved? It's time-wasting and just don't know the straightest way to the solution for a newbie without any knowledge of electronics like me, or whether it's worthy of spending time on it?

 

[GCKelloch]

I hear you on that Tim. Not sure it's worth the fuss, but you might try moving over one of the speaker wire chokes just in case it has an affect. It may even reduce the hiss. I don't know. Just need a way to tie it to the ground wire. I had some extra wire ties. I keep the volume at 7 anyway, so the hiss isn't an issue for me at all. Much better than my old Event ALP5's anyway. I'd be surprised if something could be done about the SNR at a reasonable cost. I may just leave it all as is.