Crossover Mods

[paden501]

Finally some photos.

First, a comparison of 40uf capacitors.  Not that bigger is always better, but DANG!   



Here's everything that came off of the left channel:



And here's everything that went on:



Next, a photo of the aforementioned burned up poly-switch (ewww):



And finally a photo of the finished product:


as you can see from the last photo, i replaced the polyswitch with a .5ohm Mills resistor and used 2 2.2uf capacitors in place of the 4.4uf cap that came off.

This was a pretty easy job for the most part.  The only piece that was a little tricky was the placement of the big 40uf cap.  it needed to hang off the board quite a bit in order to clear the driver connector.



I havent spent enough time with it for a real conclusion on the sound quality and I still have to replace the rest of the resistors later this week. 

[Slim-Shaddy]

Looks like you did a great job. want to recap my macs?

[paden501]

Looks like you did a great job. want to recap my macs?

If you buy the goods, I'll help you re-cap them. 

[Slim-Shaddy]

So, I e-mailed Roger Russell, the designer of the xr-16s about recapping them and this was his reply...

You might contact www.audioclassics.com. It is very unlikely that you need to do this. You have been hearing too many opinions and no proof. If anything is to go bad in the system, it would be the drivers. Save some money and time. Roger

[paden501]

Interesting.  Does that change your mind on whether or not you still want to persue the changes?

[Slim-Shaddy]

Yeah.... If I'm going to listen to anyone about changes to be made to a speaker system, it's going to be the one who designed and built them. Although, by his response it did seem like he was a little disgusted with the thought of someone else messing with "his" speakers....

[F1nut]

Sorry, but RR is wrong.....on so many levels.

[Slim-Shaddy]

Please elaborate F1. The prospect of not wasting time or money is an intriguing one. The more I read about the project of recapping speakers, it seems less and less daunting, so, I really wouldn't mind doing it. But, sinking a couple hundred dollars into a pair of speaker for no noticeable improvement is something I definitely need sold on.

[F1nut]

There's only one way you're going to find out, try it.

That said, you will note that he didn't say upgrading to superior film/foil caps and better resistors wouldn't make a different, he said that it was unlikely that they have gone bad. Even that statement isn't true as electrolytic caps have a finite life span. Whether yours have reached that point I couldn't say, but I can say that without question, upgrading will make a difference.

[Slim-Shaddy]

Yeah, I guess if I can only gain from the upgrade it's not pointless at all. I'll probably wait until I have another reason to open the speakers up. I should have done it when I refoamed... oh well. Since it seems like I'm not going to be able to get a schematic, do I just get the values from the existing caps and resistors? Here's a pic of the crossover from a XR 14. Mine will be very similar.

[bmwr75]

Replacing resistors is rarely required in crossovers.  They don't go bad with age like electrolytic capacitors.

[F1nut]

  Since it seems like I'm not going to be able to get a schematic, do I just get the values from the existing caps and resistors?

Yes, everything you need to know is printed on the parts. If you've got any questions, I'd be glad to help. I will also guarantee that you will hear a difference.

Replacing resistors is rarely required in crossovers.  They don't go bad with age like electrolytic capacitors. 

While it's true that they don't have a finite life span like electroylic caps, resistors can and do affect the sound quality, so replacing those cheap cement block types with high quality non-inductive wire-wound types is highly recommended.

[paden501]

 
While it's true that they don't have a finite life span like electroylic caps, resistors can and do affect the sound quality, so replacing those cheap cement block types with high quality non-inductive wire-wound types is highly recommended.

I'll be able to test and verify that theory tomorrow.  Right now I only have caps done (except putting a resistor in place of old polyswitches).  Tomorrow my resistors will be in, so I can do a comparison old vs new w/ just the resistors.

[paden501]

Ok so the mod is now complete.  I soldered in the mills resistors this evening, and while I was in there I added dynamat to the driver baskets and applied mortite to the driver-baffle mating surface.

The difference is stunning.  I will say that I've been running with the new caps for about a week now and haven't been blown away totally, but with the addition of the new resistors i am SHOCKED.  I've listened to several songs that I know very well in the last hour or two, using two different amps (Hafler DH-220 and a Carver TFM-25) and with both amps there is just a ton of little details in the music that were never there. 

The vocals did seem to move back in the soundstage a bit, especially on the Carver, and the stage is wider with both amps.  I can also hear a lot more 'SDA magic' than before.

Bass has more 'slam' than it did before.  This is of course even more pronounced with the more powerful Carver amp, but is noticable with either amplifier.

In the middle, I get more sense of realism.  This is especially true in percussion instruments and guitar plucks.   Instead of a 'muddy' sense of when a key or drum was struck, drum hits and guitar plucks have more crispness about them now.

All in all, I'm very pleased with the mod.

[F1nut]

Told ya!