LSi9 Crossover Modification Project

Face

I didn't think it was a night and day difference either, just a very pleasant one.

ben62670

The ones I spent some time with were LSI15's. I would think that the 9's would see near all the benefits. When my buddy and I hooked them up we both were astounded. With the 9's I think I am thinking that the 260uf is near the point of diminishing returns. Also after some review of the diagrams the 9's have the two woofers wired in parallel, and the 15's are in series. I am really starting to look at that 1.2mh inductor as much better money spent on the 9's than the 260uf cap.
Ben

DarqueKnight

Lot's of good discussion here. Of course, with any speaker modification, the end result, and the subjective interpretation of the end result, will depend on a number of factors such as:

1. The associated equipment.
2. The types of signals (music) used for evaluation.
3. Listener preference.
4. Room acoustics.
5. Listener hearing response.

This is why it is good to get as much information as possible from a variety of informed sources. Ideally, the most helpful information will come from those whose listening preferences, equipment, room acoustics, etc. approximate your own.

With regard to the shunt capacitors in the low frequency section, I don't regard them as non-effective or minimally effective on signal quality. If a component is in a circuit, it's there for a reason. The shunt capacitors are doing something. It stands to reason that, whatever they are doing, a higher quality part would do it better. When I sought counsel prior to doing my first Polk speaker mod, I was advised to replace all the capacitors with high quality polypropylene film capacitors. The bass and midrange drivers form the "foundation" of the music you hear. Treating their associated circuitry is at the discretion of the individual, but I think a disservice is realized by not doing it. It's sort of like taking one-fourth to one-half the prescribed medicine when you are ill. However, I realize that dealing with those large, expensive film caps is a pain. Since my LSi mods were "only" for speakers in my home theater system, I seriously considered skipping the low frequency capacitor replacements for my LSi9 and LSi15 mods due to the added expense and aggravation. I'm glad I treated the low frequency sections because the improvements in bass response overcompensated me for the extra time and money spent.:)

A component does not have to be in the signal path to have a big effect on sound quality. For example, cable shielding, vibration damping for parts and enclosures, and non-ferrous, non-magnetic enclosures have been proven subjectively and quantitatively to have substantial effects on sound quality. None of the aforementioned are "in the signal path".

polkatese

DarqueKnight wrote: »

With regard to the shunt capacitors in the low frequency section, I don't regard them as non-effective or minimally effective on signal quality. If a component is in a circuit, it's there for a reason. The shunt capacitors are doing something. It stands to reason that, whatever they are doing, a higher quality part would do it better. When I sought counsel prior to doing my first Polk speaker mod, I was advised to replace all the capacitors with high quality polypropylene film capacitors. The bass and midrange drivers form the "foundation" of the music you hear. Treating their associated circuitry is at the discretion of the individual, but I think a disservice is realized by not doing it. It's sort of like taking one-fourth to one-half the prescribed medicine when you are ill. However, I realize that dealing with those large, expensive film caps is a pain. Since my LSi mods were "only" for speakers in my home theater system, I seriously considered skipping the low frequency capacitor replacements for my LSi9 and LSi15 mods due to the added expense and aggravation. I'm glad I treated the low frequency sections because the improvements in bass response overcompensated me for the extra time and money spent.:)

Interesting point. This is just a thought: has anyone ever thought of engaging Polk's engineer to come up with a limited edition LSi, with all the upgraded crossover components? surely, they would have listen to your improvement recommendations as collectively, you've done enough testing and experimenting (you might even get compensated for the time and work done so far, but that's beside the point).

Another point: Polk seems to be made of a great bunch of user-friendly folks, so your collective inputs would be welcomed.

If there is an option to buy a pre-made plug and play (so to speak) kit, I would be more than interested.

Anyways, carry-on. I hope folks at Polk are taking an interest in the work you guys have done. Well done!

DarqueKnight

I don't think enough people are interested in these types of modifications to make it economically attractive to a company the size of Polk.

Even if there were sufficient demand to make standard modification kits economically viable, the wide variation in personal preference for parts would make offering a standard modification kit difficult. For example, for a speaker mod kit, which brand of capacitors and resistors to offer that would have the widest acceptance among the target consumers?

Some manufacturers (like PS Audio) officially recognize the benefits of and even endorse professionally done modifications to their products, but choose to stay out of the modification business because the money received would not cover their cost overhead. Such work is better suited for a small, specialized business with low operating costs.

Sometimes a manufacturer will offer an upgrade kit if it can be applied across the board to bring an earlier model up to the performance of a current model. Polk did this with the SRS 1.2 to SRS 1.2TL conversion kits. In such cases, the manufacturer's investment risk is minimal because the manufacturer is essentially offering a lower cost transformation of an older product to a newer version rather than tweaking a current product. People seem to be more understanding and accepting of the concept of going from something old to something new rather than the concept of optimizing something that is current.

Systems

ben62670 wrote: »

I am really starting to look at that 1.2mh inductor as much better money spent on the 9's than the 260uf cap.
Ben

I should emphisise that the results of changing this coil to air core will depend on the propensity of the stock unit to saturate.If it does then an improvement should be apparent.Otherwise there should be minimal or no detectable differences. The Jantzen from PE I linked to previously looks to the most suitable as far as DCR is concerned.

DarqueKnight wrote: »

With regard to the shunt capacitors in the low frequency section, I don't regard them as non-effective or minimally effective on signal quality. If a component is in a circuit, it's there for a reason. The shunt capacitors are doing something. It stands to reason that, whatever they are doing, a higher quality part would do it better.

Yes they are doing something and are a critical component to the design.But it is their actual capatance value that is important not the dielectric material the cap is made of.In my 20 ish years of dabbling in DIY speaker design I have never found one type of cap or another used across the woofers to be sonically signifcant.

However, I realize that dealing with those large, expensive film caps is a pain.

If one has the money then by all means replace them with polyprops.IMO you can get away using a good low ESR electrolytic.

I'm glad I treated the low frequency sections because the improvements in bass response overcompensated me for the extra time and money spent.:)

Please take this as discussion and not argumentitive.

Unless the stock cap was faulty or out of spec I cannot see how changing to polyprop could improve the bass response.The change would not have altered the woofers damping(no added series resistance)so it seems odd that such a difference was audible.
Being as more than just that part was replaced,maybe the changes made to the hi pass section have changed the tonal balance (ie less bright)giving the impression of more bass?

DarqueKnight

GV#27 wrote: »

In my 20 ish years of dabbling in DIY speaker design I have never found one type of cap or another used across the woofers to be sonically signifcant.

I wish that I had been so fortunate. I would have saved a nice chunk of change and quite a few hours of modification time.

If a particular component change does not produce audible improvements for a particular individual, then, I agree that it does not make sense to do it.

For this particular speaker modification, we have had reported results ranging from "night and day" to "just very pleasant". Someone else may chime in with "no difference at all". All would be correct because the evaluators are simply reporting what they heard from their system in their room with their ears.

DarqueKnight

GV#27 wrote: »

Please take this as discussion and not argumentitive.

Unless the stock cap was faulty or out of spec I cannot see how changing to polyprop could improve the bass response.

My admittedly limited experience has shown that when a person starts off with "I cannot see how", it indicates a certain amount of closed mindedness to a particular concept. This can preclude productive discussion.

Doing this mod either appeals to you or it does not. You either hear an improvement or you don't. My purpose for posting such information is not to win "converts", but rather, to share information with those who may have some interest. In the overall scheme of my audio enjoyment, it does not matter to me whether someone else "sees how" a particular mod or tweak will work.

Systems

DarqueKnight wrote: »

My admittedly limited experience has shown that when a person starts off with "I cannot see how", it indicates a certain amount of closed mindedness to a particular concept.

Admittedly I have some skepticism on this one aspect of the mod being such a big contributor to the differences obtained.Eventhough it was'nt done in isolation of the other mods. For what little it's worth along with my own experimenting I have read piles of engineering texts on loudspeaker design over the last couple of decades.The consensus being the dielecric make up of shunt caps in low pass filters is non critical.The fact that you notice an improvement then thats all that really matters.

In the overall scheme of my audio enjoyment, it does not matter to me whether someone else "sees how" a particular mod or tweak will work.

Exactly I agree.If it sounds good to me then it is good regardless of what someone else's opinion is.


Now I think the horse has been beat down enough.

DarqueKnight

Science used to say that the bumblebee's body was aerodynamically incorrect and therefore could not fly.

Actually, there's lots of scientific info on the effect of shunt capacitors on signal quality.

happyjack

I am looking to modify my LSI9's and LISC. I want to upgrade the capacitors. I have read posts from people who have used Sonicap with Solen and others used Sonicap with Dayton. My question is will I lose sound quality if I use all Dayton caps? I am just trying to keep the cost down.

I am using a Yamaha RXV1700 receiver as a pre-pro and Emotiva XPA2 and EXPA5 amps.

Face

It will still be an improvement, just not as much. IMO, Daytons aren't as dynamic.

Systems

anonymouse wrote: »

and you will find that the speakers are an easier load as well.

Assuming the cap was the same value and wired correctly,the load presented to the amp should not have changed.

Systems

anonymouse wrote: »

My stock 9s sounded barely adequate with an Adcom 555 II, and with a NAD 2200 PE.

Interesting ,both of those amps have hi current capability so I would not have thought that they would have any issues with 9's.

[Deleted User]

Okay. So with everyone that has a modded lsi. Anyone around the texas/oklahoma area? Lets have a listen. People that modded, hears the difference. People behind the science or what not.. different. Lets just have a get together based on regional areas and hear it. Specs, numbers and what not all aside... Lets get together somehow and give these mods a listening... Whos really up for this? I want to experience this myself. Anyone????

Halen

karlos879

I'd love to know if there are any comments from the Polk engineers on this mod.....
But I guess they couldn't really comment too much....

I'd love to know how good the difference is, but here in Adelaide, Australia there are not many shops that stock the RTiA3's, let alone the LSi series........

But I think you guys have convinced me to re-think my next choice in purchase....
And I'm pretty handy with a soldering iron, so it's going to be LSi9's with this mod for sure!

happyjack

Hey guys! I am new at this speaker mod stuff. I will be modding my LSi 9s and LSi C.
I am going to use Sonicap for all except 260uf. Does anyone have an opinion whether I should use Dayton or Solens?

ben62670

Dayton's. Cheaper and better.

happyjack

Thanks Ben

happyjack

Hey guys do you know what kind of lead wire and how much i will need for 2 lsi9 and 1 lsic
cap upgrade

Face

Between the LSiC and LSi9's, I used about 10' of wire. I used solid core, but would probably use stranded next time, solid core was a PITA to use in such tight quarters.

Conradicles

DK or others who have completed this mod to the LSi9's I have a couple of questions:
1. If I do not replace the large value caps (260uf), but only do the 1uf, 12uf, 18uf caps which value of cap would you spend the most money on?
2. Any other mods beside the capacitors and resistors been tried with success?
Thanks!
Eric.

Face

The 18uf, 12uf, and 1uf are all in series with the tweeter, I wouldn't skimp out on any of them. If you still have room, I would at least bypass the 260uf with a 1-2uf cap.

Conradicles

Face wrote: »

I would at least bypass the 260uf with a 1-2uf cap.

That seems like a cost effective idea. Can you explain what happens when I do that?

Face

I forgot to mention, you should replace the woofer's 18uf with a film cap too if you have space, if not, bypass it also.

Bypassing an electrolytic cap with a film cap lowers ESR and gives you some of the benefits of a film cap.

Face

If you want to get a little more involved, this would be a good replacement for the 1.2mh: http://www.parts-express.com/pe/showdetl.cfm?Partnumber=255-684

joochrs

3 years late but amazing write up.

Some questions:
- What we're basically doing is swapping out caps and resistors, correct? they're non polar?
- VDC ratings on the caps isn't really a concern?

I have limited soldering experience, but this doesn't look too complicated.. any advice for wanting to replicate this?

btw I can't find the LSi9 schematics anywhere, I guess they're taken down. Appreciate it if anybody got a copy to share

thanks!

Richard

deseroner

who can do this with parts and labor.i was thinking about upgrading also.

EndersShadow

deseroner wrote: »

who can do this with parts and labor.i was thinking about upgrading also.

PM Vr3MxStyler2k3 and see his thread here:

http://www.polkaudio.com/forums/showthread.php?t=118558

DarqueKnight

kevintomb wrote: »

DarqueKnight wrote: »

Science used to say that the bumblebee's body was aerodynamically incorrect and therefore could not fly.

Actually that whole story is a myth. Many People assert that it is true...but...

http://www.snopes.com/science/bumblebees.asp

I did not say that scientists proved that bumblebees cannot fly. Bumblebee flight is something that can be verified by casual observation without the help of scientists.

My point was that not everything in the natural world can be explained by science. Scientists at one time could not explain how a bumblebee could fly because they didn't have the tools to properly analyze the mechanical operation of bumblebee wings and they didn't understand all the laws of aerodynamics that applied to bumblebee flight. From what they knew, everything indicated that the bumblebee's body was too big and its wings were too small and short to create sufficient lift for the bumblebee's body, and for the heavy loads they carried.

"The calculations that purported to show that bumblebees cannot fly are based upon a simplified linear treatment of oscillating aerofoils. The method assumes small amplitude oscillations without flow separation. This ignores the effect of dynamic stall (an airflow separation inducing a large vortex above the wing) which briefly produces several times the lift of the aerofoil in regular flight. More sophisticated aerodynamic analysis shows the bumblebee can fly because its wings encounter dynamic stall in every oscillation cycle.

Additionally, John Maynard Smith, a noted biologist with a strong background in aeronautics, has pointed out that bumblebees would not be expected to sustain flight, as they would need to generate too much power given their tiny wing area. However, in aerodynamics experiments with other insects, he found that viscosity at the scale of small insects meant even their small wings can move a very large volume of air relative to their size, and this reduces the power required to sustain flight by an order of magnitude."

https://en.wikipedia.org/wiki/Bumblebee#Misconception_about_flight

In summary, bumblebee wings act more like helicopter blades than bird wings or the wings of aircraft. That is why bumblebees can hover in place, move laterally, and move backwards...like helicopters.

I find it odd that you would expend the effort to attempt to "refute" a comment I made in 2008, yet, when I recently asked you to explain your stereo evaluation methodology, you tucked tail and ran. You have interesting priorities.

Reading comprehension is fundamental.