SDA-2B Crossover Parts List

inspiredsports

Beautiful work!

The problem is that I'm leaning toward Sonics for the 40uf, and 30uf is as big as they go so piggybacking is a must. I know we're splitting hairs here, but I guess getting everything in one place appeals to me and so many people swear by them.

I will be mailing the boards and parts when they are all accumulated in a week or so.

Another question, (and I just learned they aren't called "coils"); does anyone ever worry about the integrity of all of the old inductors involved in a crossover network?

F1nut

Like this,

You don't need to be drilling holes. Simply dog leg the bottom lead into the existing hole.

You hot glue the upright cap on the bottom and were it rests against the inductor. This offers much better support once the board is mounted.

Leave the stock inductors alone.

inspiredsports

inspiredsports wrote: »

Another question, (and I just learned they aren't called "coils"); does anyone ever worry about the integrity of all of the old inductors involved in a crossover network?

I guess I answered my own question after finding this thread between F1nut, Stu and Matthew Polk himself . . .

http://www.polkaudio.com/forums/showpost.php?p=846791&postcount=21

. . . and I am convinced that as FInut states, . . . "I do believe I will leave my inductors stock" . . . is the best answer.

inspiredsports

The Photo in thread #33 Photo looks like a 30uf on top and a 10uf underneath (nicely done, by the way!).

I'm still leaning toward 20uf + 20uf as the best solution electronically and it's actually a tiny bit lower cost that way. It looks like it will work if care is take to locate the bottom 20uf as close to edge of the board as possible.

F1nut

Correct. Those are the boards for the 4.1TL. You should have no problem mounting a 20uF on the bottom, it'll stick out a bit more, but you don't have the cabinet space issues that I did.

Make sure you hot glue and zip tie that bottom 20uF. Run the new zip tie thru the original zip tie for the large inductor above.

inspiredsports

My wife truly thinks we're all absolutely nuts planning this stuff out to the nth degree.

I can't describe in words how good I feel finally getting this project quantified, and the enjoyment I experience by getting this stuff just right.

l joined this forum just 12 days ago and have received so much valuable information that I don't know how I can ever repay it, but I will stay involved and try to help others as I learn more.

Systems

ShinAce wrote: »

I can't remember the material type for that cap though and somehow that bugs me.

Silver Mica.;)

inspiredsports wrote: »

Another question, (and I just learned they aren't called "coils"); does anyone ever worry about the integrity of all of the old inductors involved in a crossover network?

Coils don't were out and from your pic it appears like they are all air cores (albeit sloppily wound ones)Therefore it is no advantage to replace them.If laminate or ferrite core were used in series with woofers then changing it to an air core of the same inductance and DC resistance might be benificial.Stu points out the potential for saturation issues in cored inductors.

ben62670

I'll stick to drilling the tiny hole required to secure the big caps in place;)

F1nut

Another pic, this time from the bottom. Note the wiring using the original holes. Also, note the Cardas binding posts.

F1nut

Why? It's not needed, just extra work.

ben62670

Extra work? It's a tiny hole the diameter of the cap's leg. It is also stronger than hot glue for sure. BTW I like the way those Cardas binding posts:)

F1nut

Maybe I'm missing something, but drilling a hole that's not needed IS extra work and I dare anyone to try to remove one of the 30uF caps I've hot glued in two places without cutting it with a razor knife first. Besides, the hot glue helps dampen the cap, which is a good thing.

ben62670

Considering how long it takes to do the upgrade the one extra step that takes more time to grab the tools than it does to make the two little tiny holes isn't a big deal. I also use the hot glue. Is it necessary to drill the holes? No, but I think it is just that little bit nicer. I don't see why you are against my suggestion. There have never been any complaints about my work, and I know there haven't been any complaints about yours. I am certainly not criticizing your work, so take an anti grumpy pill there Mr President.

inspiredsports

Holy, moly Polkmen, I didn't mean to for this thread to end badly. Both are great ideas. A normal board is drilled for the leads fo poke through to be soldered so it makes sense to drill. Glue is great for damping and should be added at the end. It's a Win / Win situation

F1nut

Well, not exactly. The holes are punched when made the boards are made and have specific purposes. The holes for components that need to be soldered have copper exposed for said purpose. I'm still not clear why Ben is drilling new holes.

At any rate, half the folks attempting these upgrades have little to no experience as judged by some of the hack jobs I've seen. Yes Ben, I know you know what you are doing, but I think it's bad advice to be telling others to drill holes that aren't needed. Nothing against you.

inspiredsports

Someone warned me earlier to hang on to my wallet.

Somehow the $27 on sale for $13 posts from partsexpress.com don't look so hot anymore. The Cardas posts do look intriguing, and my 20+ year old 10' gold plated Monster Cables are probably up for debate too.

I hate to wish a bad economy on anyone, but I hope these dealers do some heavy discounting after the holidays in February.

inspiredsports

F1Nut,

Sorry for the confusion. I'm sending all to Ben to do the build for me. That might clear things up,

F1nut

I'm not confused, I figured as much and I'm still against drilling holes. In fact, mounting a 20uF under the board pretty much rules it out.

inspiredsports

I haven't done any board soldering in many years and don't feel this project is the right one to use as a training mission. It's great to learn all of the diverse opinions knowing that a couple of decades of experience are out there and folks have taken the time to think these challenges through and have "been there, done that." Thanks again for sharing good info.

gdb

I'd gladly pay $20-$30 for a well filmed,step by step instructional DVD that shows how to do these (and others)!! Could be a source of income for someone so inclined.

gdb

I've been wondering....do these XOs get warm/hot while in use,and if not, would it be advantageous to enclose them in a foam covered box to isolate them from vibration??

inspiredsports

gdb, it's amazing that you posted this as I was just daydreaming about exactly the same thing minutes ago.

I was thinking that the group has just about covered everything, and I was thinking outside of the box (or more accurately "inside" of the box) about new ground to cover to try to add something constructive to the collective knowledge base. Shielding the crossovers with a sound deanener was first on my list!

One crazy idea, (and someone is welcome to beat me to the punch as both sets of my Polks are apart now) is to pad and seal my camcorder and a battery powered light source inside to watch for vibrations of wires, crossover networks, drivers, passives, etc. that might be imparting bad vibes to the sound.

I'm not sure exposing my handy-cam to all that vibration will prove to be a good idea, but I'm sure curious to know what's going on in there.

inspiredsports

The old SDA-2B's will be singing by Christmas as the parts list comes together . . .

My RDO198-1's arrived from Polk, Dynamat from Woofer's Etc., and Silver Wire Interconnect for my CD player plus FINISHED CROSSOVERS (special thanks to Ben for the exceptional craftsmanship). Mortite will be here in a day or 2.

#################################

Future readers PLEASE NOTE: These crossovers have been specially modded with a custom valued 5.8uf Sonicap and 2.7 ohm Sonic Craft Mills Resistor to allow for an upgrade from the stock SL2000/RDO194-1 to the "TL" SL3000/RDO198-1 tweeter. Compare finished images below with original image in POST #1 and note where the "C5" board area is EMPTY.

DO NOT FOLLOW THIS MOD UNLESS YOU UNDERSTAND YOU ARE "UPGRADING" TO THE RDO198-1 which WAS NOT THE STOCK VALUE TWEETER.

This also causes the need to modify the female negative ground lug on the white wire that connects to the crossover as the RDO198 male ground terminal is about 2 times wider than the original.

#################################

Face

Expect to hear a large difference over stock, I was more than pleased.

ben62670

You get your ears on them yet?

inspiredsports

ben62670 wrote: »

You get your ears on them yet?

Yes and no; PM and email sent with details / snapshots.

inspiredsports

I am soooooooo blown away by the sound that will only get BETTER over the next what, 300 to 400 hours.

I can't isolate any one thing at this point as the Silver Interconnects from ny CD player to Amp, Dynamat and Sonicaps and Mills are now just 3 hours old, and I haven't even Mortited or gotten the Cardas Posts installed yet.

I listended to 3 complete CD's that I know quite well and have vastly different charestics: Gerorge Winston "December", Jimmy Page "Outrider" and Pink Floyd "Dark Side of the Moon".

I know the 21 yr old 12uf primary tweeter caps were once white and had slowly bled goo to the point they were yellow when removed so that was one area for big improvement. I think that might have narrowed the sound stage quite a bit as tonight I caught myself with this HUGE GOOFY GRIN ON MY FACE as I listened to instruments up to several feet beside and in front of the point source. Not so much sound behind, yet but I'm sure it will only get better as things progress.

WOW !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I'm cooking them overnight with my new IsoTek Full System Enhancer and Rejuvenation Disc that is purported to speed the burn-in process along.

On second thought, I may just pop in another CD !!

WOW !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

F1nut

I'm glad you're happy with the new sound.

I know the 21 yr old 12uf primary tweeter caps were once white and had slowly bled goo to the point they were yellow when removed so that was one area for big improvement.

Ummm...no, they were always yellow. When a cap leaks, it leaks onto the board and you can't miss it.

inspiredsports

F1nut wrote: »

Ummm...no, they were always yellow. When a cap leaks, it leaks onto the board and you can't miss it.

The tops of the 12uf caps where the leads enter had a puffy yellow stuff that looked like it had bled over the edge. It appeared kind of like the "styrofoam in a can" aerosol insulation you can buy that expands, but before it dries.

At any rate, I've had the system on for almost 24 hours straight now, getting Seven 65-minute cycles of the IsoTek disc mentioned above in while I slept. I'm still skeptical, but I do think it helps as the tweet are loosing harshness much more rapidly I had expected. Sounds mighty good already!

inspiredsports

I modded my SDA-2B crossovers as detailed in post #54 and other posts above to move up from the SL2000/RDO194-1 to the SL3000/RDO198-1.

This presents 1 small wiring problem in that the old SL2000/RDO194-1 used the small male blade at both + and - poles.

The RDO198-1 uses a larger male blade on the - side, so either the wire needs to be snipped and a larger female lug installed, or an adapter found/made. I prefer to adapt to keep the wiring harness stock.

The photos below show my solution, but the adapters are extremely cheap blades I picked up at Radio Shack just to get the system going.

I haven't been able to find a source for a high quality larger size female to smaller size male blade adapter. Does anyone have any ideas?