Took apart the lsi7's

madmax

I took apart the lsi7's tonite and the crossover is very simple. Two 12mf and one 16.5mf caps, two resisters and a few coils. I was very impressed with the enclosure. As thick and heavy as they are polk still included bracing! VERY well built! I'm thinking they will be excellent upgrade material with good caps and resistors. I'm wondering if the coils should be upgraded? The speaker stands are in the works as well. Very nice book shelf speakers!
madmax

organ

Let me know your results if you upgrade the caps and stuff. I might try it on my LSi9. Heavy woofers on those LSi eh?

Maurice

Joey_V

pictures!! we want pictures!! how are the lsi woofers? sturdy?

Early B.

Max -

I, too, would be very interested in your results, especially the cost of the upgrade and the sonic difference it makes.

I've heard that many high end speakers use cheap parts for their crossovers, and upgrading these parts improves the sound quality.

Is the upgrade a simple DIYer or do you need any special electronics skills?

madmax

The components in the LSi7's seem to be reasonable but of course you can always upgrade. Right now I'm trying to figure out who makes what values. The caps are 12mf but so far I'm only finding quality 10mf ones. Assuming I find what I need I'll tell about the mod and what it does to the sound. (If it does anything). To my ears these are very respectable book shelf speakers. After break in they sound very large and pleasing.
madmax

tonyv1

Parts Connexion has some 12 mf caps (check under MultiCap PPFXS, MulitCap PPMFX, Solen PB and Solen PPE). They range from $5.65 to $56.05 each. I did see a Audio Note Silver foil cap for $1,173.50!!!!!!!!!!!!!!!!

Joey_V

how does improving the caps improve the sound? can someone please explain to me?

i know that the entire audio stream (the current) is separated by crossovers set at specific frequencies, usually at freq. that are optimum for the drivers. now, would upgrading to better crossovers (caps?) improve the specificity of the freq being transmitted to each driver?

madmax

The audionote's should be fine. Lets see, $200 for the speakers, $7043 for the caps, $40 for the resistors, that is only $7283 for the complete upgrade!

madmax

Mazeroth

Pictures, please!

radkrisdoc

Madmax,
Ive been thinking of upgrading my LSI9's crossover too. The caps in the 7's and 9's are mylar.....that's what polk advertises them to be. I dont know what the difference would be if u change em to Polypropylene, cos from what I know, both types are used in high end systems. Krell's Lat1 uses Polypropylene.
You said that there were a few coils there......if they are anything but air core, it would be worth changing them to like say 8 guage air core coils. The problem here is, we need to know the exact resistance of these coils. Any change in resistance will change the drivers' Q values. That will affect bass and punchiness accordingly (either increase or decrease em - its purely subjective, not a real frequency response improvement). I was planning on emailing Polk CS for the correct values. While reverse engineering is possible, emailing them is a lot easier I'll also be following this thread closely.
Something interesting here:

http://www.northcreekmusic.com/COILS.html

madmax

If you get any info from polk please pass it along.
Thanks,
madmax

radkrisdoc

Definitely.

jdhdiggs

Dumb newbie question:

Why don't you run 6 2mF caps in Parrallel. This should eliminate most of the varience between cap values giving mor consitant performance.

madmax

Because of the cost and size. You are correct in theory though.
madmax

HBombToo

Originally posted by jdhdiggs
Dumb newbie question:

Why don't you run 6 2mF caps in Parrallel. This should eliminate most of the varience between cap values giving mor consitant performance.

I have been hesitant to do that beacuse of the differing time constants of each cap. tau is what im trying to recall.

I would much rather find 1 big fast cap prior to a rebuild.

h

Joey_V

no one has replied to my question... .

how does caps improve sound? how does upgrading the crossovers improve sound?

radkrisdoc

Joey,
There are different types of capacitors. Among them, the commonly used capacitors in loudspeaker crossovers are electrolytics, paper in oil capacitors and caps made of plastic dielectrics like polypropylene (PP) and mylar (metallized polyester). Each of these types have different characteristics, the parameters being voltage rating, frequency loss, size and weight among others. Ive just given you a very superficial overview, without being too detailed.
Generally, electrolytics are obtainable in large values and do not show significant losses in the lower audible frequencies. They are thus suitable for woofer low pass crossovers. PP and other "plastic" capacitors (polystyrene, polyester) are best in high pass filters esp for tweeters.
Apart from technical nitty gritty, how do they sound?
Ive yet to see (hear ) the difference between mylars and PP caps. Metallized caps are generally supposed to have a higher treble output, some even call it ragged. Foil caps are said to be smoother.
Inductors are important too....when we take an example of a system that uses a high quality 10 guage speaker cable, the only significant resistance that comes in series will be the coil's. How does that affect system performance? Transient response is affected by alterring (increasing) the speaker's electrical Q (Q es). Boomy bass. Q can also be increased by lowering cabinet volume and increasing the length of the duct. In bookshelf speakers like the LSi9, this might be taken advantage of. Thats why there's a minimal overemphasis of mid bass giving a feeling of nice bass output.
Theory apart, a speaker system with ideal Q may not sound as good. Different designs, like the Butterworth, Chebychev and Bessel have standard Q values. Whatever the design maybe, it all depends on the listener. You may even like a mod thats likely to measure up differently on the bench. The important thing is, if the listener thinks it sounds exactly (or at least as close to it as possible) like a live performance, nothing need be changed.

dorokusai

I sourced all the inductors for my SDA1C's from North Creek, as mentioned previously by Radkris. They custom wind any size/value for you.

I recall a statement from George(North Creek):

" The coils - 22 gauge sounds terrible." He was speaking of the Polk inductors.

It will require some creative board placement, but I also received the measurements on the inductors, larger gauge, air core...and they were close to the size of the stock. I chose a 14 gauge from North Creek.

North Creek also believes that their resistors are better than Mill's...but I would take whichever is cheaper, as they are both very good.

Solen was my pick for Caps.

radkrisdoc

Madmax,
I sent an email to Ken Swauger and he's sending me a hard copy of the crossover schematic with component values (for the 9's). Will keep you posted. Kris

dorokusai

Does anyone have the schematic for the LSi7's?

DarqueKnight

Originally posted by radkrisdoc
I sent an email to Ken Swauger and he's sending me a hard copy of the crossover schematic with component values (for the 9's). Will keep you posted. Kris

Polk used to refuse to send schematics for current speaker products. Have they changed their policy or is the LSi series scheduled to be discontinued soon?

Joey_V

i hope the lsi arent to be discontinued soon... i just got mine!

DarqueKnight

Originally posted by dorokusai
I sourced all the inductors for my SDA1C's from North Creek, as mentioned previously by Radkris. They custom wind any size/value for you.

Doro,

The Polk engineer that I consulted with prior to doing my first SDA mod advised against replacing the inductors because they were custom made for the electrical properties of the particular drivers they were used with. He further advised that if I insisted on changing the inductors, I should only do so if I was going to send the stock inductors to a vendor to be custom matched. If I understand your post correctly, this is what you did. It will be interesting to read of your results with the custom inductors. I may have to "operate" on my SDAs one more time.:)

DarqueKnight

Originally posted by Joey_V
no one has replied to my question... .

how does caps improve sound? how does upgrading the crossovers improve sound?

Better Parts = Better Sound

Let's use an automotive analogy where the tires on a car will be analogous to the crossover in a speaker.

Any tire that is round and that holds air will serve to assist the car in getting to its destination. However, installing different types of tires on a vehicle can have drastic effects on its acceleration, braking, and ride comfort characteristics due to differences in rubber formulations, internal constuction, tread design, etc.

Any electronic component, even a straight wire, will alter a signal that passes through it. Higher quality parts allow the signal to pass through with a much lower degree of alteration than lower quality parts.

radkrisdoc

Raife,
The schematic is not something that I really would want if I need stuff for an upgrade. Crossovers are not that terribly difficult to trace and get them back on paper. The important thing that's needed for the upgrade would be the values and characteristics of the components (inductors, capacitors) that were meant to be used when the speaker was designed. One way to do that without Polk CS help would be to send the coil so the values can be measured; if values are obtainable its easier to place an order.

LSi speakers use good quality caps (Mylars). I expect the coils to be of good quality too. Even then, there are two types of coils in the mod market (copper foil and Litz coils; both air core) that have me interested in an upgrade. And polypropylene caps too.
Only problem is, I will not be able to do all this right now even though I'd love to. Madmax will probably be ahead of me. Ive got a bunch of stuff to do at this point in my life. Hopefully in a while I will have more time on my hands.

ezc

Madmax,
You should change the wire from the binding post to the xover board. The stock wires on my 9 xover is maby 18 or 20 guage? I replaced them with monster Z1 about 10 guage with thick strands & fine strands ( lows & highs) Noticible improvment Id say about 5%-7% improvment. I use the Moded 9 xover im my LSiC. I have not changed any caps or other wire yet. I want to change the speaker wire & connectors to the speaker with multi guage wire. here is a link to some pics of the x over mod. http://www.ezconnection.org/ebay.htm Easy mod needed to drill the board slightly to make room for the larger wire. I would like also to install better binding posts later too! May be wbt or somthing that the wire is directly soldered to or connected to the post rather than having a connector bolted to the post with a nut. Always in search of better Pic & Better Sound, a never ending journey!

radkrisdoc

ezc,
WOW what a bottle neck! Definitely needs an upgrade with better wire. Did you identify what core the coils use? Nice pics there.
Kris

ezc

No I didnt even look at what type of coils were in the x over. I just wanted to replace the wire. I dont have enough knowledge to tweak the x over. If I do more than I can handle Ill probably mess it up! I would like to get the x over to cross over sooner but Im not sure how to do that!

radkrisdoc

Ive got the schematic and crossover details for the LSi9. It looks like the dedicated bass driver's Q has been increased to give the mid bass bump. The inductor's DCR reads 1.6 ohms. The other mid-bass driver has an inductor with a DCR of only .31 ohms. The tweeter's got an air core inductor; the other drivers have laminated steel cores.
By the way, the photocopier at Polk badly needs a new ink cartridge
Madmax....if you want the LSi7's details, ask Ken. I have to work on this copy (the 9's) and make a readable electronic version of it. Kinda like draw the schematic and all; it is definitely not "scanable". Oh, by the way, this was VERY interesting.....the tweeter's frequency response (anechoic) as shown on the Vifa website has a dip of around 3 db between 15 Khz and 20 KHz; then from around 22 KHz there is a massive peak of 7 db at 35 KHz. I was very interested in how Polk had smoothened it out. I didnt expect to find a RC contour before the tweeter's crossover. An RC contour does two things: 1. decreases the drivers output (the resistor does its job...this is to match the tweeter to the other drivers) and 2. the bypass capacitor increases the treble, much like a tone control treble boost. All they have done is give the treble an ever so slight increase.....maybe around 1 to 2 db, from around 15 Khz. Thats my guess. That has resulted in the smooth curve published in the Sound Stage review. Well done there! But, like I noticed, the sound stage curve stops at 20 Khz. I dont know what happened to the 35 Khz peak....it got smoothed out too, I guess.
Now, I plan to do this:
1. Find a speaker terminal or modify the terminal so I can get the crossover outside.
2. A nice ABS box for the crossover
3. 12 gauge wire all the way. Even for wiring the components, I am not going to use a PCB. Gonna wire it like those older tube amps.
4. Replace the caps with metallized PP. WIMA or Solen. The bass electrolytic with a Black gate or Cerafine. Havent looked into that as yet....dont know if there are biploar caps from the BG or Cerafine line.
5. Change laminated coils to air core, while maintaining stock DCR.
6. For the tweeter's RC contour, I may go for a switch....with gold or silver plated contacts. Im going to include this option: to be able to change the cap values of the RC contour with a flick of a button. Probably three, will keep the stock value and call it FLAT; a High position and a Low position. Maybe 2 db of boost and cut. For this I will need some time.....to experiment with the other low and high values. After that is done, I set the boxes behind the entertainment center and run wires to the individual drivers.
This also gives me an opportunity to bi or tri amp the system in the future. Oh yeah and the future....I have committed myself to the 9's. Kinda like marriage lol.....I might add speakers but Im not gonna let these go. Have too many plans for them

ezc

radkrisdoc, What the controls freq that the low driver comes in? If I wanted to have the low driver come in earlier what would that take? New coils, New caps w/different values? I would like the low driver to play down as low it plays now but x it over earlier. Im not sure what it comes in at currently either. If you have a Idea let me know. If it is a easy to do I may want to try it & if it dosnt work out Ill just put it back the way it was!

radkrisdoc

Hi ezc
I quite didnt understand what your first question was. The first driver functions till 200 Hz. The second mid bass driver till 2.4 Khz. Anyone who does not have access to measuring equipment or an anechoic chamber (like you and me) would do well if they upgraded the type of caps/coils keeping stock values.
Your second question.....you said you wanted to cross it over earlier. I take it you meant reducing the crossover frequency from 200 to say 120. I dont think there would be a benefit in doing that. May I ask what made you ask about crossing over the speaker earlier? If you want the same bass as you are getting, do not change stock coil values. You can change the type of coil from laminated core to air core without changing stock values.

I am talking about drilling two holes in each speaker terminal (the plastic "plate"); this needs to be done to bring the crossover to the outside.....there are only 4 binding posts on stock speakers, I will need two more on each. If you think you can handle all of that and also fabricate a crossover, then you can try it. If not, its better to leave em as they are. One should remember, the 9's are from Polk's premier LSi series and the design and quality of the components are very good. You already have an awesome speaker......
I will be doing all of what Ive planned over an extended period of time.....will have to upgrade my electronics first anyway to be able to hear any difference the crossover upgrade makes. I suggest you wait till someone (who's done things like this before) here finishes a LSi mod. Maybe then you will know if its 1. easy and 2. if its worth putting in all that time and effort.