LSR 305 and 308 discontinued.............read below

[oivavoi]

One thing I haven't mentioned that is underlying my perspective here is that I've looked at a lot of cumulative spectral decay plots of horn-loaded compression drivers. I'm over-generalising here, but I've rarely seen specific evidence in the CSDs of anything that might be considered a HOM, nor have I found that CSDs for better-quality horn-loaded comp. drivers are less clean than direct-radiating tweeters in the frequencies we might expect to find HOMs.

Interesting. I have never seen CSD measurements of compression drivers. But I have noticed that some science-oriented manufacturers who use waveguides or horns have said that compression drivers can be less "smooth" or less "clean" than domes or ribbons/planars, like Dutch & Dutch and Kravchenko Audio, who makes the drivers for the Morrison omnis I'm awaiting. In the absence of publicly available measurements, we don't know what this relates to. But it does seems to me like these subjective experiences relate to something.

 

[andreasmaaan]

Interesting. I have never seen CSD measurements of compression drivers. But I have noticed that some science-oriented manufacturers who use waveguides or horns have said that compression drivers can be less "smooth" or less "clean" than domes or ribbons/planars, like Dutch & Dutch and Kravchenko Audio, who makes the drivers for the Morrison omnis I'm awaiting. In the absence of measurements, we don't know what this relates to. But it does seems to me like these subjective experiences relate to something.

Perhaps. My experience looking at CSDs is that there's nothing special about them that would allow one to discern a horn-loaded CD from a dome just by looking at the CSD (apart from CDs staying cleaner at louder levels ofc).

Different compression driver/horn combos have different CSDs, and there is no obvious pattern or any consistent aspect to the results that suggests any particular structural shortcoming related to horn-loading IME.

But IME, there tend to be fewer ribbons out there with messy CSDs than there are domes or CDs. And of course, once a CD gets above around 1.75" voice coil diamater / 1" exit, it cannot play clean in the top octave due to diaphragm breakup.

In any case, there are many examples of drivers with very clean CSDs in all three categories.

Planars I've never measured or looked into.

 

[andreasmaaan]

@oivavoi I've read the papers now and can give a brief description of the contents (I'll read them again more thoroughly when I have more time).

The paper entitled "Simulation of Harmonic Distortion in Horns Using an Extended BEM Postprocessing" investigated only harmonic distortion. There was no investigation of HOMs.

The paper entitled "On the Velocity Distribution at the Interface of Horn Driver and Horn" measured 4 different 2" exit compression drivers and found measurable HOMs in two cases, and none in the other two. Note that 2" exit drivers are a worst case scenario; for high-fidelity high-frequency reproduction, an exit of no greater than 1" is recommended. The paper concludes by saying: "It is difficult to give a conclusion at this early state of the investigations."

The paper entitled "Do Higher Order Modes at the Horn Driver’s Mouth contribute to the Sound Field of a Horn Loudspeaker?" is more interesting I think. The first thing I should admit is that the very complex maths involved in the predictive model they use are beyond my understanding.

Also important to note is that it restricts its measurements (again) to two 2" exit drivers, one a single diaphragm design and the other a coaxial. Again, we would expect HOMs to be much more pronounced in a 2" exit driver than a 1" exit one. The study also restricts the horns used to a tractrix horn and a square conical horn, neither of which is designed with HOM-minimisation in mind. The particular conical horn chosen is far from optimal, as it has a square throat (the compression drivers' exits are circular), which is a recipe for diffraction. It indeed measures worse.

The study also ends somewhat inconclusively. It finds that in these four (2 CDs x 2 horns) cases, HOMs were able to be measured and that the measurements agreed reasonably well with the predictive model. The authors suggest, however, that it is not clear whether the contribution of HOMs to the on- and off-axis frequency response is "negligible" or not.

Looking at the results, I would expect the HOMs to be of more than negligible impact in some circumstances at least. The study finds (as predicted) that the HOMs present in the exit of the drivers are excited more strongly by the square throat of the particular conical horn used than by the tractrix horn.

It would be nice to see measurements of a 1" exit CD on a horn that is designed with HOM-minimisation in mind.

My cautious prediction on the basis of these studies would be that in such a case, HOMs would be negligible/inaudible.

As I said, I'll investigate further and report back (maybe we should start a new thread for this topic?).

EDIT: should also mention - in both these studies the HOMs were found to reside in the higher frequencies as predicted, i.e. 4-6KHz or higher. Not sure if that's of interest but it might be something you can try to relate to your subjective experiences listening to 2" exit horn-loaded high frequency drivers.

 

[oivavoi]

Wow! That was quick, @andreasmaaan ! Thanks!

Yes, a new thread is a good idea. “To horn or not to horn?’

 

[andreasmaaan]

Wow! That was quick, @andreasmaaan ! Thanks!

Yes, a new thread is a good idea. “To horn or not to horn?’

Hahaha

 

[jhaider]

Thanks! Enlightening comments.

As with everything in speaker design, there might be trade-offs. There is no doubt that non-flat waveguides may improve the dispersion characteristics and the polars. At the same time, isn't it the case that what is commonly called a waveguide (i.e. not a flat baffle) does something with the soundwaves beyond controllring dispersion which a flat baffle does not? I'm thinking of HOMs etc, re: Geddes. One may discuss the audibility, but my understanding is that it's there, and that it's measurable (using the right measurements). On the other hand, THD probably becomes lower, because the drivers get an easier load. So I do think there's a trade-off.

Except for controlling dispersion, I don't think that either an acute waveguide or an obtuse waveguide (such as on your Morrison speakers' tweeters) inherently does anything special to the sound waves that a flat baffle does not also do. Perhaps because the big problem of dispersion disruption is taken care of with a well-chosen waveguide, lesser problems become more audible. I think that is better than accepting very audible big problems, but that is a judgment call.

 

[JustIntonation]

Just a little update as far as the new lsr305 mkII goes.
Maybe I was a little bit over enthousiastic earlier. But still I think it's a great speaker.
It's not very critical in the treble, but it is very flat in frequency and does contrast a weak mix and a great mix. Can handle all genres as well.
It's a bit sweetening and not the most detailed or clean, but all in the right area to my taste. Very balanced.
The bass is good for a 5inch when listening at low to low-med levels for EDM for isntance, but gets too distorted / coloured / resticted from mid levels to high levels. Don't know how much of this is the driver (I've heard better from a 5" but not by miles, all 5" drivers are restricted in 50 to 100Hz bass quality to a degree) or how much of this is remaining cabinet resonances (if I end up keeping them I'll mod them with a cross brace and/or lead-bitumen sheets on the outside.)
Right now I'm listening to them with the LSR310S sub. My room can handle the very low frequencies fairly well, it's still relatively even sounding not too large peaks or dips below 40 Hz. But the sub itself does not have the quality I'm looking for. It sure is fun but its a bit too "slow" and sometimes a bit detached. (edit: in my room / setup. I don't want to blame the sub. Perhaps a better idea would have been to set it up with a measurement mic, I think I feel the 50-120Hz or so isn't a flat as it was with just the 305p mkII. edit2: it is close to as flat actually but below 40Hz or so it gets boomy for me, could it be that a port this low makes for a boomy bass? (probaby tuned to something like 30 or 25Hz?) Kind of feel like this is what I'm hearing and it may not be my room.. No previous experience in here with a sub though.)
Will try out the LSR306p mkII soon and compare it against the LSR305p mkII. Hopefully the 306 does bass a bit better as it's a 6.5" driver, without sacrificing anything in the mids. I'll know soon..

 

[JustIntonation]

And another update regarding the 310s sub with the LSR305p mkII.
I spoke too soon in my previous post. When set up correctly it's a great system.
I have it placed inbetween the speakers now on the same straight line as the speakers, not further back as suggested by JBL in the manual. I guess this is because the speakers are on stands on ear level and at a close distance to my ears as nearfield, the sub is now on an imaginary sphere distance with the speakers from my head. Sub is now also well away from any walls and I have it connected unbalanced to my DAC, set to +4dBu input level and connected with balanced cables to the 305p mkII which are set to -10dBu (according to the manual) and volume to full.
The sub volume setting is where my listening tests went wrong so far. I set it by ear to -6 before (it's a detented volume control for the sub) and this is where it was too heavy in certain ways though I felt it was the right volume (probably because of being used to the bass ported sound of the LSR305p without sub) but the right sub volume for my setup appears to be -7. (and definately not equal to the volume setting of the 305 or 308 like the manual says, I can't see how that would ever work for anybody!)
Sounds fantastic now, very open yet balanced and deep when called for. Already I couldn't live without it anymore Not only are the extra octave below and clean bass at any volume well worth it, but perhaps even more so is the removal of the ported sound of the LSR305p without sub! It really "opens up" the sound giving more detail throughout the spectrum, not only the mids but even the highs it seems, strange how that works (no more masking?).
The removal of the 50-60Hz? port resonance of the LSR305p is of course replaced with the port resonance of the sub at I guess 30Hz or so but I find this much less bothersome now that the sub is at the right volume. The "boom" I was disturbed by before was indeed the port I found out. After stuffing it with socks the boom disappeared but the bass quality lessened (harmonic distortion below 40Hz?). But now at the right volume the boom is no longer a concern (to be clear, no longer stuffed with socks).
So recomended combo if your room can handle it! My room is about 160m3 (and keeping door open to an adjacent room about the same size), but I loaned the sub today from my little brother and he has a smaller living room with standard height ceiling and the sub doesn't work there way too many strong resonances it's a total mess sadly.
I'll be building a small studio in a corner of my room coming month (with a lot of absorption, I like it very dead from bass to treble) and will be getting my own LSR310s. Once finished I'll do some measurements of the LSR305p mkII and LSR310s and post them here.

 

[Blumlein 88]

And another update regarding the 310s sub with the LSR305p mkII.
I spoke too soon in my previous post. When set up correctly it's a great system.
I have it placed inbetween the speakers now on the same straight line as the speakers, not further back as suggested by JBL in the manual. I guess this is because the speakers are on stands on ear level and at a close distance to my ears as nearfield, the sub is now on an imaginary sphere distance with the speakers from my head. Sub is now also well away from any walls and I have it connected unbalanced to my DAC, set to +4dBu input level and connected with balanced cables to the 305p mkII which are set to -10dBu (according to the manual) and volume to full.
The sub volume setting is where my listening tests went wrong so far. I set it by ear to -6 before (it's a detented volume control for the sub) and this is where it was too heavy in certain ways though I felt it was the right volume (probably because of being used to the bass ported sound of the LSR305p without sub) but the right sub volume for my setup appears to be -7. (and definately not equal to the volume setting of the 305 or 308 like the manual says, I can't see how that would ever work for anybody!)
Sounds fantastic now, very open yet balanced and deep when called for. Already I couldn't live without it anymore Not only are the extra octave below and clean bass at any volume well worth it, but perhaps even more so is the removal of the ported sound of the LSR305p without sub! It really "opens up" the sound giving more detail throughout the spectrum, not only the mids but even the highs it seems, strange how that works (no more masking?).
The removal of the 50-60Hz? port resonance of the LSR305p is of course replaced with the port resonance of the sub at I guess 30Hz or so but I find this much less bothersome now that the sub is at the right volume. The "boom" I was disturbed by before was indeed the port I found out. After stuffing it with socks the boom disappeared but the bass quality lessened (harmonic distortion below 40Hz?). But now at the right volume the boom is no longer a concern (to be clear, no longer stuffed with socks).
So recomended combo if your room can handle it! My room is about 160m3 (and keeping door open to an adjacent room about the same size), but I loaned the sub today from my little brother and he has a smaller living room with standard height ceiling and the sub doesn't work there way too many strong resonances it's a total mess sadly.
I'll be building a small studio in a corner of my room coming month (with a lot of absorption, I like it very dead from bass to treble) and will be getting my own LSR310s. Once finished I'll do some measurements of the LSR305p mkII and LSR310s and post them here.

About the sub even effecting the treble, I'm not surprised. I've done room correction for friends, and often tweak the target curve to their liking. With some descriptions of them wanting different upper-midrange treble quality I go straight to the low end and tweak the curve. They ask why I do that, but stop worrying about it when they hear the results. The overall tilt and balance of either end of the spectrum can be effected by adjusting the other end in some circumstances. I remember early Etymotic phones were sometimes accused of not having enough bass. They came out with a new model addressing that. Reviews indicated it did fix the problem. Measurements revealed they tilted down the top three octaves by about 3 db over that range.

If you want to experiment with port damping in the woofer there is a better way than socks. Cut some straws in half, bundle them together and tape around the outside. You'll figure out how to size it right in a try or two. Slide this in any port you wish to damp, and it will slightly, but usefully damp the port. You can adjust damping by using large diameter drinking straws, medium drinking straws or those small straws used with coffee at fast food joints.

 

[JustIntonation]

About the sub even effecting the treble, I'm not surprised. I've done room correction for friends, and often tweak the target curve to their liking. With some descriptions of them wanting different upper-midrange treble quality I go straight to the low end and tweak the curve. They ask why I do that, but stop worrying about it when they hear the results. The overall tilt and balance of either end of the spectrum can be effected by adjusting the other end in some circumstances. I remember early Etymotic phones were sometimes accused of not having enough bass. They came out with a new model addressing that. Reviews indicated it did fix the problem. Measurements revealed they tilted down the top three octaves by about 3 db over that range.

If you want to experiment with port damping in the woofer there is a better way than socks. Cut some straws in half, bundle them together and tape around the outside. You'll figure out how to size it right in a try or two. Slide this in any port you wish to damp, and it will slightly, but usefully damp the port. You can adjust damping by using large diameter drinking straws, medium drinking straws or those small straws used with coffee at fast food joints.

Thanks for the port straw suggestion.
But if my hearing was not fooling me the relation of the porting is not just frequency response but perhaps also the port reduces distortion? I'm not familiar enough with sub construction but is this possible? At least I thought I heard the quality of the subbass deteriorate when putting in the socks, deteriorate in that it sounded distorted below 40Hz or so. Pulling the socks out made the boom come back in those frequencies but the distortion disappear / smoothness reappear. I prefered the boom and more clean smoothness over the distortion. (and the boom is now not bothering me anymore I think now it's correct in level, all the tracks that displayed the boom before in an unmusical manner, most of the time it was fast dry acoustic kick sounds, are now perfect to me)
And if the above is correct, then putting straws in would probably have the same effect but in a lesser degree? Still indeed perhaps worthwhile to experiment with.

 

[Blumlein 88]

Thanks for the port straw suggestion.
But if my hearing was not fooling me the relation of the porting is not just frequency response but perhaps also the port reduces distortion? I'm not familiar enough with sub construction but is this possible? At least I thought I heard the quality of the subbass deteriorate when putting in the socks, deteriorate in that it sounded distorted below 40Hz or so. Pulling the socks out made the boom come back in those frequencies but the distortion disappear / smoothness reappear. I prefered the boom and more clean smoothness over the distortion. (and the boom is now not bothering me anymore I think now it's correct in level, all the tracks that displayed the boom before in an unmusical manner are now perfect to me)
And if the above is correct, then putting straws in would probably have the same effect but in a lesser degree? Still indeed perhaps worthwhile to experiment with.

You are likely correct about what the socks did. What the straws do is maintain a smooth laminar flow in and out of the port. Yet passing thru the narrow passages will resistively damp the port. Which will usually alter tuning very slightly, and reduce excess boom. It would alter the Q of the woofer/box. The socks don't do this.

Look the cost is near nothing, making the straws with tape is a few minutes work. It is non-permanent. It truly can potentially improve the woofer response to your liking. If you don't find it helpful, slide out the straws and you are done. I think it worth the experiment just to see if it does anything positive for you. There are no permanent downsides.

It is no panacea, but it can work. A friend years back had the large bipolar Mirage M3si speakers. Pretty good, but a little wooly loose on the low end. He ended up having to use the tiny coffee straws, but that made a big difference in tightening up his woofers just enough it became a non-issue afterwards. And yet not so much is drastically altered the speaker tuning.

 

[RayDunzl]

You can adjust damping by using large diameter drinking straws, medium drinking straws or those small straws used with coffee at fast food joints.

Maybe you can develop and sell a Cardas-like straw selection, scientifically bundled (or just guess) in various overall diameters and lengths for different speaker's ports and desired tunings...

 

[Blumlein 88]

https://www.stereophile.com/content/radioshack-optimus-pro-lx5-loudspeaker-measurements

Here JA uses some straws in the port of the underdamped woofer in RS LX5 speakers.

Then measures them showing impedance and output differences with and without straws in the port. So they really do make a difference. Here is one of the graphs of output. Below 300 hz you have open ports top, straws in port middle and port blocked bottom.

I also happen to have a pair of these LX5's. I used them for a center speaker year before last until replacing with a LSR305 in my video system.

 

[Blumlein 88]

Maybe you can develop and sell a Cardas-like straw selection, scientifically bundled (or just guess) in various overall diameters and lengths for different speaker's ports and desired tunings...

View attachment 15424

Cardas straws I like it. You think $200/port is a good price?

 

[RayDunzl]

$200?

For which level?

Ultra, Reference, Signature, etc...

 

[Blumlein 88]

$200?

For which level?

Ultra, Reference, Signature, etc...

Good point. Let us start with Reference.

Then in a year or two additional research can result in improved design for the Signature series. Finally in about 3 or 4 years we'll have truly learned how to make straws work in an out of this world way. Which is when I'd introduce the Ultra Carbon Fiber series with carbon fiber straws.

 

[Sal1950]

Cardas straws I like it. You think $200/port is a good price?

Oooooooooooo, the Golden Ratio design, awesome. Should get rave reviews and sell very well.

 

[Wombat]

Cardas straws I like it. You think $200/port is a good price?

No. DIY it.

 

[JustIntonation]

Will try the straws thing later when studio is finished and I have a measurement mic (will use measurements to set any final eq adjustments if needed). Though not sure if it'll easily work with the LSR310s as it has a non round port with a wide mouth getting narrower inside but I'll experiment. Perhaps EQ will turn out better for me if adjustment is needed.

 

[JustIntonation]

Btw. Still testing the sub.. At loud volumes (daytime here again) the whole system is not as good as with low volumes. I'm not sure how much of this is still room, how much is because of more "port activation" at higher volumes, how much of it is perhaps cabinet resonances (the sub certainly doesn't survive the "knock test", worst knock test I've ever heard), how much of this is other distortions perhaps amps of the 305p's, and how much of this is because at louder volumes my room reverberations are getting more audible.
Have the sub untill tomorrow, will build my studio coming month and then get my own 310s sub and do listening tests and measurements. (but I'm already convinced this is the way to go for my current low budget)

edit: Well.. It's not ideal.. There's a golden window for volume where things sound clean enough, below that there's the self noise of the 305p's (easily audible at 1-1,5m distance) and above that ideal volume things are not clean enough.
A good demonstration is for instance Beethoven's 7th second movement (Vanska recording). It starts clean but in the noise floor of the 305p's and the louder parts are already in the not clean enough zone (large parts, not just the loudest peaks). I think it may well be the amps that are just not very good..
I'm considering building my own speakers and sub. the 305p's + 310s combi goes for aroung 700 euro here. That goes a long way towards building my own system especially since I already have an Anaview AMS0100 amp which is very good. And I think once finished my room will be worth it. I am happy I now know that sub + nearfields is a very good thing though!