Maiden voyage: 5Jr upgrade

On3s&Z3r0s

Someday soon I hope to be TL'ing a pair of 2B's, so in preparation for that I decided to practice up on a pair of 5Jr+. It was definitely an interesting learning experience, so I thought I'd share some of the good times. Here's a list of the improvements:

1. Upgraded the tweeters to 194's
2. TFLF's bitchin rings on the MW's and PR's
3. DYE-NUH-MAT!
4. New caps and resistors
5. New binding posts

The deets:

As anyone who has installed them can tell you, the rings are awesome to work with. It was a little tricky in the 5Jr's because they all have to be bent to go in and the 6.5" aren't perforated like the larger ones, but it wasn't too difficult to bend them back into shape. Also, Polk luuuuv'd their glue and some had to be cut away from the opening for the PR's in order to seat the rings for those. It was good times working with a box cutter in that small-ish cabinet.

Next interesting bit, on the 5Jr crossovers, the PCB's are mounted upside down with all the electronic goods sitting inside the big inductor core. Weird, but whatever. I thought about flipping the boards but it seemed like it would be a pain in the **** to move everything around to match the flipped connection points, so the new cap and resistor just got mounted on the printed side of the board.

I was trying to economize a bit and got the Dayton 1% caps. They both measured exactly 12uF on the button! Contrast that to the Sonic Caps I got for the 2B's which measured at 12.2 and 12.5. (I hope those live up to their rep.) I bought .5 ohm resistors to use in place of the polyswitches, but when I measured the resistance on those I got .3 ohms for both so I decided to just jumper that connection.

The binding posts were tricky too. Here's where trying to economize bit me as I got some gold Dayton posts that have a little knob on the end as a connection point instead of an eye. After they were installed in the cup it was a pain to get the wire to hold and solder it in the cramped quarters. When doing the second pair I decided to re-use the little L-brackets from the old posts rather than soldering directly to the terminals. It worked, but a close listen revealed that speaker was slightly muted compared to the direct soldered terminals. So, those XO's had to be dis-assembled and re-done. Bummer, but I had to go back in anyway as H9 told me to not be so half-assed about things and clean the flux off my PCB's.

They sounded pretty good to me right off the bat, but I couldn't give them a serious listen at first since I finished up at 1am Sunday night. Yesterday after the first 10 hours of burn-in I gave them their first real audition. All I can say is wow. The tweeters really make the speaker in this case.

The music that used to sound shrill and spiky on the SL2000's is much better. Paul Desmond's clarinet and Milt Jackson's vibes are much improved. One downside, though, some horns/woodwinds sound a little more sibilant than I remembered on the SL2000's. I'm hoping this is common to Polk tweeters during burn-in. I remember noticing the same thing when I first got my Monitor 70's (I know it's a completely different tweeter), and at least I don't notice it on them anymore, not that I've been listening as closely or to the same stuff on them lately.

Anyway, all in all I'm pretty stoked to have at least not made them worse. (I don't think I can take credit for making them better as I think that was mostly the tweeters.) And now I'm much more confident for tackling the 2B TL in a few weeks.

heiney9

On3s&Z3r0s wrote: »

I was trying to economize a bit and got the Dayton 1% caps. They both measured exactly 12uF on the button! Contrast that to the Sonic Caps I got for the 2B's which measured at 12.2 and 12.5. (I hope those live up to their rep.) I bought .5 ohm resistors to use in place of the polyswitches, but when I measured the resistance on those I got .3 ohms for both so I decided to just jumper that connection.

Nice Job!!!

Just so you know there is no way to test a cap with a DMM to tell if it's in spec or not, outside of an open connection. You need to use an ESR tester for caps. With caps it's all about the materials and construction and the Sonicaps more than live up to their hype and rep. Simply measuring them in the manner you did really tells you nothing about how they will sound or perform.

Now you're ready to TL the 2B's, and please use Sonicaps, you can thank me later :biggrin:

H9

P.s. about the 150 hour mark you'll really start to hear the improvements in the work you've done.

Oldfatdogs

Nice Work ,did the new 194 drop in or did you have to do a little modifying to the cabinet?

heiney9

I didn't realize the 5Jr+ only had one cap per speaker. That seems odd to me since my 5B's have two caps. 1-in series with the tweeter and 1-as shunt for the woofer.

Is there another cap not shown in the photo's?

H9

On3s&Z3r0s

heiney9 wrote: »

Just so you know there is no way to test a cap with a DMM to tell if it's in spec or not, outside of an open connection. You need to use an ESR tester for caps. With caps it's all about the materials and construction and the Sonicaps more than live up to their hype and rep. Simply measuring them in the manner you did really tells you nothing about how they will sound or perform.

Now you're ready to TL the 2B's, and please use Sonicaps, you can thank me later :biggrin:

Thanks! That's good to know about the caps, I did get Sonicaps all around for the 2B's... I know folks put a premium on getting them matched, and these were supposed to be. Even measuring the way I did it's not even a 3% difference so not a big deal I suppose.

Oldfatdogs wrote: »

Nice Work ,did the new 194 drop in or did you have to do a little modifying to the cabinet?

The 194's are a complete drop in. Just unscrew the SL2000, unplug the pos/neg wires (no soldering required), remove the gasket (if you're using it instead of Mortite or similar), put the gasket on the 194, reattach the wires and screw it in. The cut-out and screw holes line up perfectly.

I didn't have to modify the cabinets at all for any of the mods other than using TOOLFORLIFEFAN's rings, and this thread does a fantastic job of describing that process: http://www.polkaudio.com/forums/showthread.php?t=103241

heiney9 wrote: »

I didn't realize the 5Jr+ only had one cap per speaker. That seems odd to me since my 5B's have two caps. 1-in series with the tweeter and 1-as shunt for the woofer.

Is there another cap not shown in the photo's?

H9

Nope, the cap you see is the only one in the crossover. The only thing on the other side of the PCB now is the small .19mH inductor for the tweeter and the jumper where the polyswitch used to be. There's no shunt cap... I don't know enough about XO's to know why they decided to omit that.

zingo

Those speakers hold a special place in my heart and I also pimped out a pair as you have done and they are great speakers for the money. Enjoy the improved sound and be sure to let the tweeters and crossovers burn in for at least 100 hours before doing any critical listening.

heiney9

On3s&Z3r0s wrote: »

Nope, the cap you see is the only one in the crossover. The only thing on the other side of the PCB now is the small .19mH inductor for the tweeter and the jumper where the polyswitch used to be. There's no shunt cap... I don't know enough about XO's to know why they decided to omit that.

Maybe those in the know like Face or FTGV can comment. The 5B's and 5JR should be about the same except the PR is smaller as is the cabinet. I'm sure there is a reason.

H9

FTGV

On3s&Z3r0s wrote: »

There's no shunt cap... I don't know enough about XO's to know why they decided to omit that.

The slope or rate of roll off on the woofer is different in the 5B vs the 5 jr's.The 5B has 12 db 2nd order electrical filter whereas the 5jr's single series coil is only a 6 db per octave(1st order)electrical.I assume Polk engineering felt that by using a shallower slope on the woofer in the 5jr resulted in a better blend with the tweeter in both frequency and phase.

FTGV

heiney9 wrote: »

Just so you know there is no way to test a cap with a DMM to tell if it's in spec or not, outside of an open connection.

Actually Brock my Fluke will measure capacitance to better than a 2% accuracy for values below 100uf.

On3s&Z3r0s

The DMMs I have definitely can do capacitance. They may not be quite as accurate as an LCR, but they always agree with each other on the cap values at least. Neither one of them does ESR testing... I googled it and it seems like there might be a way to fake it, but it's spilt milk at this point anyway. Since I got the sonicaps I'll put those in and hope for the best.

I don't know if it's burn in or what, but after 30-40 hours they seem to be imaging a little better. A big part of that probably has to do with my initial bungle with the binding posts and the fact that I corrected it after the first 10-12 hours of burn in and after my first listen made it clear that something was wrong. My wife's happy enough with them that she wants me get rid of the SDA's now. That was not exactly the desired effect. :rolleyes:

ben62670

FTGV wrote: »

Actually Brock my Fluke will measure capacitance to better than a 2% accuracy for values below 100uf.

Mine too

FTGV

On3s&Z3r0s wrote: »

. Neither one of them does ESR testing...

Nor should there be any need to.