Upgrading the JBL-S26 Crossover (long) (1 Viewer)

[Brett DiMichele]

The 70Hz lowpass on the mids would be passive... The 70Hz
Highpass on the subs would be active..


I am not sure what kind of Bookshelfs I am going to do yet.
I have a million other things I need to do first. But after
I get everything else done that I need to do I will be looking
into a DIY 2 Way Bookshelf to run with my AV-12 Sealed Sub
untill I have the plans and money to do a big set of ribbon
line arrays..

I need to figure out a budget (less wood costs) for the
bookshelfs. I am guessing $300-$500.00 for drivers and XO
parts will do fine.. Of course this won't buy Scan-Speak
Revelators but I could probably do a nice bookshelf with
the HiVi M8a Magnesium Midbass driver and maybe a Vifa
Concentric tweeter or something along those lines.. Maybe
even something with a Seas Excel Midbass with phase plug.

I will have to see what "Kits" are out there since I have
no knowledge on designing XO's from scratch nor do I have
the proper equipment like a good RTA Mike and MLSSA Software
and a Cap/Inductance Bridge etc..

 

[Michael R Price]

Sounds like a plan, though you'll need a pretty freaking big capacitor to get the 70Hz filter. I mean, what's the value of that cap in your center speaker?

Oh also about speaker kits, the "audioworx" M8a design looks really nice (up there with the best standard drivers available), the design should be published soon. From what I know about your taste though, you might want a speaker with 2 woofers. If you only have one you'll have low efficiency (tube amps won't like them) and somewhat less output potential. On the other hand that would also decrease the quality of components you could afford. Me, I use the Kit281s... I know they are not the best when it comes to "refined" midrange and treble, but they're pretty dynamic and, well, they just sound good.

But, maybe you don't want those... I'd bet the general level of sound quality at that price point is not much of an improvement if any, over your AR9s unless you compromise dynamics and go with a small monitor type speaker. Power costs money, after all. I'd just start saving up for the real deal.

 

[Brett DiMichele]

Mike,

That's a good point about the sound quality. The question
is would it be an improvement over my 9's. Honestly I am
getting real critical these days (Probably too much so..)
but if it sit back and look at things in a not so critical
view the AR9's are pretty amazing for a "mainstream" speaker.

Considering I have $585.00 tied up in the pair they are even
more amazing at that price point.

I don't know if a $500.00 set of bookshelfs would be that
much of a step up. Ribbon Line Array's on the other hand....
Those will cost roughly $2500.00 not including wood and misc
building materials. But I am sure they would compete with
anything 20K+ if done right.

My biggest problem is that I want everything.. I don't
need it all I just want it all

 

[Michael R Price]

Well, if you are critical about the AR9s... what don't you like about them? Maybe there are other ways to improve their sound more to your taste without needing "interim" speakers. Redoing the crossovers is a good start, I would guess.

I sometimes notice a lot of flaws in my system (such as, at the moment, only one speaker works ) but I try to put it in perspective. For example, some upper midrange and treble sounds (certain frequencies, or something) tend to distort a little bit and songs with those sounds don't sound as nice when I crank it up. Why? Maybe because I have a crappy CD player, or midwoofers playing out of their range, or cabinet resonances, or... whatever. But it doesn't matter because as a whole music is pretty enjoyable and I enjoy continuing to improve the system at relatively little cost (of money).

 

[Brett DiMichele]

I think my biggest gripe is the bass.. I am getting very
spoiled about bass these days. The bass that the dual 10's
produce is clean but I feel I can make it cleaner. Also
if you turn the subs off and let just the mids and tweeter
play there is absolutely no impact.. This is due to that
100Hz lowpass on the mids.. I just feel that the mids
should play lower than what they do.. And rely less on the
subs to produce 80 to 100hz information.

The tweeters are beautiful.. Probably one of the best Ti
tweeters I have heard.. They are not fatiguing and not
ringy at all.. Off axis response is damn near as good as
the on axis (thanks to D'Apolitto no doubt).

I think the cabinent can be better dampened internaly so
that has me wanting to coat the internal walls with something..

I have been thinking about spraying the inside with asphalt
undercoating and wrapping the outside of the midrange enclosures
with dynamat and placing a deflex pad inside the mid's
enclosures and removing the pollyfill that I put in there.

 

[Lee Bailey]

Dean, thanks for the good ideas. I'm gonna upgrade the crossover components on my Polk R40 and CS245. Will get some damping material later though. I'm leaving the inductors alone, since I don't know what value they are. For $60.00(including shipping), I got Solen polys and Mills Resistors shipping on the Brown Truck. Yes, the current caps on these speakers are standard Electrolytics. It will be interesting to see the improvement.

Would I be better off to replace the current PCB the components are on? Or is ok to just solder in the new parts where the old ones were? I'm just wondering if it is better to have all the components connected with wire vs the PCB land patterns.

 

[Lee Bailey]

Got my front and center channel speakers refitted with the new caps. It made a huge difference in the sound quality to me. Opened up the high end. I found myself listening to music a lot more during the weekend. I'm going to still get them rebuilt onto a new board mount though. The new caps are huge due to their voltages! I opened up the surrounds, which are RT15i's, they are using a 1.0 mylar bypass cap. I found it interesting that they are only using an inductor on the woofer, no cap at all. I've ordered the parts for that already, with some Auricap film and foil bypass caps for replacement of the mylar.

 

[Brett DiMichele]

Lee,

Cool beans!

I will be ordering all the stuff to revamp my XO's in a
week or so.. I am replacing everything though, Resistors,
Inductors and Caps.

I am not sure what I am doing on the caps yet.. I can go
with something like the Dayton Audio Metalized Poly caps
for the big values and then bypass them with the AudioCap
Theta Film and Foil caps or just go with the large value
Theta's and forgo the bypass caps.

I am also debating on what inductors I want.. I could go
with Jantzen or Alpha Film and Foil inductors or go with
14 Awg Perfect Lay air core's for close to the same price.

 

[Lee Bailey]

I did replace the resistors as well with the Mills brand. The inductors on mine are not air core.

 

[BrianAe]

Since you all seem knowledgeable about cross overs, I'm just curious to know if any of you have an opinion on the DiAural cross over circuit that a couple speaker manufacturers use and promote as a differentiator. Is it for real or bunk?

Here's a link to Aperion Audio's site: http://www.aperionaudio.com/basics/ba_diaural.html

 

[Lee Bailey]

Since it was developed by the folks from Kimber, it looks like the real deal. However, there is a very small amount of information on their website. For something that's been around for 2 years, it's amazing that only 1 speaker manufacturer has licensed to use them. It would be interesting to know how much this license affects the price of the speaker to the consumer. It sounds like a very simple way to drive your speakers.

 

[Brett DiMichele]

Lee,

No aircore inductors at all? I would think the mid and
tweeter inductors would be bobbin wound air cores while
the large woofer inductor would be iron (that's how mine
is..) But then again every manufactuere does things diffrently.

 

[Chris Tsutsui]

I have a question...

Lets say there's a capacitor that's rated at 4uf, 24uf, and 60uf in my crossover. They are all bypassed by the tiny blue cap that says 0.01k 250V.

I would like to replace the 4uf with a 3.9uf sonicap, and the (24uf and 60uf), with (24uf and 62uf) axon true caps. The problem is these values are not exact and the design asks for bypass caps as well.

I figured that since I'm using the sonicap, I won't have to bypass it, and the tweeter should sound great. With the midrange and woofer, I will likely bypass those with 0.01uf Dayton film and foil BP caps.

Should I just order the parts, or do I need to hunt more for the correct capacitor values?

 

[Brett DiMichele]

Chris,

From what I have read as long as you are within a 2% +/-
Threshold it most likely won't be audible. The factory
components are at least +/- 10% so even if the caps are
smaller or larger by a couple tenths of a value you aren't
going to hear it..

 

[Chris Tsutsui]

I figured it wouldn't be a problem . Looks like i'm ready to order.

Oh and Brett, I found out that my 0.01K 250V blue caps are identical to 0.01uF bypass capacitors. I guess 0.01k = 0.01uf.

 

[Lee Bailey]

Brett, there are no inductors at all on my tweeters on my Polk speakers. These are only 2-way speakers.

 

[Brett DiMichele]

Lee, In lots of designs they just use a cap on the tweeter
and that's sufficient. But the woofers usually have an
inductor. What the hell do I know though, I am ANYTHING BUT
a Crossover Expert!

 

[Lee Bailey]

Brett, there is an iron core inductor on my woofers. On the tweeters, there is just a cap and a resistor in series with the cap.

 

[Brett DiMichele]

Lee,

That makes sense

 

[dean_g]

Wow, this thread really took on a life of it's own.

Inductors -- never change out an inductor in the tweeter ciruit unless you know both the mH and DCR value of the inductor. Parts Express sells an inductance/capacitance meter for less than $50. This thing is a must if you play with crossovers. The DCR of the old inductor can be checked by using a multimeter set to ohms. A decent MM can be had for less than $20.

The DCR of the inductor on the bass is not as critical as the ones used in the high pass section. However, going to an outrageously low DCR will actually change the tuning point of the cabinet. I recommend not going to anything larger than 14 gauge. The Perfect Lay Solens are nice,and affordable. It will change the tuning point a little, but the upside is the increased damping and control of the driver.

The DCR of the tweeter/midrange sections are critical -- NEVER change these values as they are integral to the voicing. Now, definitely ALWAYS yank an iron core and replace it with an air core. Iron cores are used for their power handling abilities -- not their sound quality. After market air cores from Madisound and Parts Express are usually good to 300 watts. So, if you go with aftermarket parts -- there is no need to worry about the power handling ability of the inductor. Also, once you meter out your iron core inductors -- if you can't find a comparable value, Madisound custom winds them for dirt cheap. Whoa, a whopping $4 a piece.

Capacitors: Metallized polypropylenes are good caps, but they are a step down from film and foil. Some people argue the ability to hear the difference between a good metallized polypro and a film and foil. A good metallized polypro costs almost as much as a film and foil (compare Auricaps to AudioCaps for example).

The small blue mylar types found on PCB's of less quality crossovers are used to bypass lesser quality electrolytics. If you stay with the PCB, you almost still have to use a bypass cap of some sort. I find it just as easy to get a piece of Baltic Birch plywood and just make a new board. It's ridiculously easy to trace out a PCB (usually only takes minutes) -- and then transpose the circuit to a point-to-point wired board. A nice way of doing it is to use the Northcreek method (brass machine screws and pegboard). They sell everything you need at their site (www.northcreekmusic.com), and the book that teaches you how is only $5. At any rate, if you stay with the PCB(s) and the bypass caps -- use something like the Solens as the main caps and the Thetas in the bypass positions. If you build a new board -- I say to hell with bypassing. And yes, keep the values as close as possible.

Chris

Lets say there's a capacitor that's rated at 4uf, 24uf, and 60uf in my crossover. They are all bypassed by the tiny blue cap that says 0.01k 250V.

The 60uF cap is a huge value. If the speakers are less than five years old, I would leave this one alone. I'm sure it's an electrolytic -- and it will be good for at least 10 years. Replace the little blue POS with a nice AudioCap Theta film and foil. This should work out well. 60uF in a plastic cap, or even something like a 12 and 18 paralled -- would be ridiculously cumbersome to work with. I do see that the Axon 62uF is 1.5" by 2.5 inches, which makes me question whether it is really a metallized polypro or not. At any rate, whatever you end up using here -- if it's not film and foil -- bypass it with a film and foil.

I would like to replace the 4uf with a 3.9uf sonicap, and the (24uf and 60uf), with (24uf and 62uf) axon true caps. The problem is these values are not exact and the design asks for bypass caps as well.

Sonicap huh. You been talking to Jeff from Sonic Craft? He's a great guy, and knows what he's talking about. He's also extremely anal about caps. I'm sure he is having these caps made for him, but I don't know by who. I would imagine they are comparable to the Solens and Axons. If I had to hedge a bet -- I'd say Axon makes them for Jeff. The 24uF Sonicap is a good choice. However, I have no idea how you are going to get a 24uF cap on that PCB. It's probably easier to make new boards, and just get rid of the bypass caps on the tweeter/midrange circuit. The 4uF cap is probably the one in series with the tweeter, and the last thing it 'sees'. Make this a nice film and foil. BTW -- Auriaps are NOT film and foil. Look at the Audiocap Thetas and Hovland Musicaps.

I figured that since I'm using the sonicap, I won't have to bypass it, and the tweeter should sound great. With the midrange and woofer, I will likely bypass those with 0.01uf Dayton film and foil BP caps.

The tweeter will be happier with a 4uF Theta.

Should I just order the parts, or do I need to hunt more for the correct capacitor values?

Brett is right about the values -- your are fine.

What speakers are we talking about here?

Lee You did good.

Brett Don't do anything radical to those AR's. Just change out those caps and the inductor for the bass to a Solen Perfect Lay, or Music Coil from Northcreek.

All Anyone who doesn't want to deal with the meter deal, feel free to PM me. Send me your inductors I will measure them out. Just pay the shipping.