SDA-1C Crossover upgrade - Journey Begins

robosdad

robosdad wrote: »

You could build them like mine. Madisound has everything in Clarity except the 40uf. The 40uf doesn't have to be the best of the best so just use Dayton for that one. I mixed Dayton and Clarity when I rebuilt my Monitor 10's and I think they sound great! You'd be all in for less than $150 for caps.

That sounds perfect. I'll check it out! Do you think its $150 for both or for one crossover? [/quote]

You used the 5% for the 20 and 40 mf values and the 3% for the rest, correct? So I could effectively use Dayton for the 20 and 40?

And these are polypropylene not foil?

Thanks!! As you can guess I’m learning on the go here.

F1nut

Both of those types are film caps.

Gardenstater

robosdad wrote: »

Wait am I using film and foil or metallized polypropylene? I thought the latter!

I'm pretty sure that if you are on a budget you can forget about film and foil caps. They are higher end and larger as well.

robosdad

invalid wrote: »

robosdad wrote: »

That’s wonderful. I think you have pointed me down the kind of path I was hoping for. Thank you!!

I actually wasn’t planning on changing out the resistors. I’m under the impression that’s not necessary- the specs don’t drift. Am I wrong?

You are correct, but better resistors make them sound even better. You could just buy the sonicap capacitors and upgrade the resistors later.

For six resistors at $12 a pop I'll probably hold off on those for now. Had no idea resistors could be so boutique! (though I might be demonstrating my lack of electrical understanding) Will order my capacitors soon, though- likely Dayton for larger values (lows) and Clarity for the smaller values (highs).

Thx!

robosdad

Ok two questions before I order my caps:

They don’t offer a 4.4 mf, so should I go with a 4.7 mf or run two 2.2 in parallel? (About same price)

And why is it ok to just remove the c4 cap? (750 pF)

(Getting clarity cap CSA except Dayton for the 40 mf)

F1nut

4.4uF, https://www.soniccraft.com/product_info.php/gen-sonicap-44-uf-200vdc-p-433?osCsid=4r3mf8omt4nr21g5mdc2v6t0c2

The resistors are only $9.44 at Sonic Craft.

The 750pF is a bypass cap, which is no longer needed when upgrading to film caps.

joebass3

robosdad wrote: »

For six resistors at $12 a pop I'll probably hold off on those for now.

Actually 8 resistors if you replace the polyswitches with 0.5 ohm resistors (recommended). 🙂

joebass3

robosdad wrote: »

Ok two questions before I order my caps:

They don’t offer a 4.4 mf, so should I go with a 4.7 mf or run two 2.2 in parallel? (About same price)

I would use two 2.2 if using Clarity. If you get a 4.7 and it reads high, you could easily be over 10% of the specified value.

robosdad

OK, my replacement caps have arrived! Will solder them in next week. Do I really need to remove the old caps' leads from the board (never solder sucked before!) or can I snip off the old caps and then solder the new caps' leads onto the old leads? If that's no good, and you can explain why to a novice, I'd appreciate it!

F1nut

Desoldering is pretty damn easy. Watch some videos online.

pitdogg2

robosdad wrote: »

Do I really need to remove the old caps' leads from the board.

Yes !

robosdad wrote: »

can I snip off the old caps and then solder the new caps' leads onto the old leads?

Do not do this^^^^^^^

You're asking for big trouble with bad solder joints. Exspecially if you're a novice at soldering.

Let me ask what kind of soldering station do you have? Lets start there first.

txcoastal1

If you have any old electronics to destroy, practice on those first

robosdad

pitdogg2 wrote: »

robosdad wrote: »

Do I really need to remove the old caps' leads from the board.

Yes !

robosdad wrote: »

can I snip off the old caps and then solder the new caps' leads onto the old leads?

Do not do this^^^^^^^

You're asking for big trouble with bad solder joints. Exspecially if you're a novice at soldering.

Let me ask what kind of soldering station do you have? Lets start there first.

Yikes! Sounds like a resounding no! But for my own curiosity, I still would like to know WHY snipping the existing caps out and soldering the new caps to existing leads would be problematic. Seems so much simpler.


As for my station, I have a digital soldering iron with pencil tip, a pair of helping hands, a small fan/filter, some (lead-free) solder and some resin flux and a newly acquired solder sucker that I'm still having a bit of trouble with- practiced a bit on some PCBS and I could remove most of the solder but then there'd still be a little trace left in the hole hanging onto the leads.

I've soldered a few components to PCBs before, but never had to remove any until now. Still very much a novice so definitely welcome any tips!

F1nut

You need a plunger type solder sucker, the large version. Heat the solder until it melts and with the sucker in the other hand immediately push the button. You want the tip of the sucker right on the melted solder.

Throw that lead free solder away and get some Cardas Quad Eutectic. You don't need the flux either.

F1nut

Solder sucker, https://www.amazon.com/Solder-Desoldering-Sucking-Teflone-Silicone/dp/B0BHHKW6H9

Cardas solder,
https://www.amazon.com/Cardas-Soldering-Eutectic-Silver-Solder/dp/B015X68HXW

joebass3

Probably no reason you couldn't cut the capacitor out and solder to the leads, but it would look butchered. Plus it's so easy to just remove them that it really makes no sense to do a half &ssed job. I had good luck using a solder wick. Give it a shot and definitely use Cardas Quad Eutectic solder.

robosdad

I’ll check out the good solder. Pretty pricey. Wish they sold just a couple of feet of it! Thx all.

joebass3

robosdad wrote: »

I’ll check out the good solder. Pretty pricey. Wish they sold just a couple of feet of it! Thx all.

https://www.ebay.com/itm/334074362655?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=Z5tP63kISuO&sssrc=2349624&ssuid=kLEP-O5WQHm&var=&widget_ver=artemis&media=COPY

robosdad

@joebass3 perfect!! Just ordered. Thanks a ton!!

robosdad

Got my nice solder! But how do I actually remove the crossover board? I'm assuming step 1 is removing the passive radiator (done) and disconnecting the leads from the drivers, but then what? I assume the board comes off the cylinder that it's attached to, but I don't see any fasteners.

Thanks!

F1nut

Remove the binding post plate (4 screws) and the crossover will come out with it. The board is attached with 4 plastic standoffs. Pinch the small tab on each standoff to lift the board off. The standoffs are easily broken, so be careful.

robosdad

I see those white plastic standoffs- thanks for the heads up about their fragility.

Would those 4 screws be on the back of the cabinet? All I see is a single hexagonal bolt head on the back of the cabinet a few inches above the speaker wire terminals. Is that what's attaching the binding post plate and it's just a different fastener method on different models/years? Also, when you say "binding post plate" does that refer to the cylinder sandwiched between the crossover board and the inside of the back of the cabinet?

THANK YOU!!!

robosdad

I just googled "binding post plate" and see that's the speaker wire terminals. But my crossovers are a located above that. Should have added a photo earlier, here you go.

robosdad

joebass3

Just remove the Allen head bolt. That is what holds the crossover in place.

F1nut

Ah, some are attached to the plate, others are held on with that bolt as joebass states.

robosdad

Ok, one cap out, and one cap in. Solder sucker starting to become a little easier. I see I'm supposed to remove a few things "Remove the small silver mica caps and the polyswitches" according to OP. Which ones are those exactly? C4? I don't see anything else on the board that seems (to my uneducated eye) to correspond.

Edit, OK going back I see that C4 gets removed- is that a tiny capacitor I'm guessing? Is that the only thing I remove?

Gardenstater

The little blue device in your picture near the large yellow mylar 12uf capacitor is a polyswitch. Most people remove them and replace them with a small value resistor (0.5 Ohm or less) but some people seem to like the sound when they just install a jumper.

robosdad

So sorry to keep asking all these questions- hopefully another noob will see this and learn from my unknown unknowns I keep running into...

Anyway, what temp would you recommend for the solder (using the Cardas silver eutectic). The leads on the caps are so thick they're proving hard for me to solder- keep bumping the temp up and I'm at @500 degrees. Don't want to go much hotter and don't want to leave the iron on there for too long. Am I being too careful?

EDIT: Talking cap lead to cap lead (for the two 10 mf caps I'm soldering in parallel)

Gardenstater

I'm not a super experienced solderer but I would probably have it up more around 600 or even higher. It also depends upon the size of the tip on the soldering iron (area of contact) and the thermal mass of what you are soldering. If you are worried it never hurts to put some heat sink clamps near the component. If soldering one lead to another I'd just use a single hook and minimal solder. I don't like seeing people twisting the heck out of them and putting a necessarily huge amount of solder on. Solder doesn't conduct as well as the leads do so keep it to a minimum.