1.2 TL X-over upgrade

[analog97]

Now that it's safe to go back in the water, I wanted to post my synthesis of the threads on the 1.2 TL x-over re-do's. I would very much appreciate a read-thru from those who know about this. I just don't want to miss anything.

1. Remove the polyswitches. Use a jumper wire.
2. Eliminate the 750pf silver mica bypass capacitors.
3. Remove all existing capacitors and resistors.
4. Use Sonicaps (Gen 1) per recommendations, .22uf, 12 uf, 13.5uf and 27uf.
5. Use Mills resistors (12 watt).

I think this reflects the collective wisdom of those who have experience and knowledge. The parts list was previously posted by Lasareath, I believe. Did I miss anything? Thanks in advance. Looks like a Thanksgiving project!!

[avguytx]

Thanksgiving project? Man, I'd have a hard time waiting that long to do the crossover! :D

[woofiepaws]

I did my 1.2tls two weeks ago and I have never soldered before in my life. That Cardas Quad Eutectic solder is way easier to work with than the stuff Polk used.

Go for it.

[shadowofnight]

My SRS's were still a little chilly from bringing them inside when I pulled the crossovers for the mod :) It helped that I already had the parts.

[schwarcw]

Looks like you did your research. You are correct on all counts. Don't forget the binding posts (Vampire or Cardas) and upgrade the SDA cable. Send me a PM professor, I've done three sets of SDA's, you live about 8 miles away. I'll give you a hand.

[ben62670]

I don't believe in removing the poly switches, but replacing them is a good idea. If someone cranks your speakers, or you have an amp failure, voltage spike, and fries your tweeters you will be very upset. I also don not like extra components in the signal path, but you can get the appropriate poly switches for free from Polk CS. Just ask for Ken.

[analog97]

Ben,

I understand your concern for speaker protection, but the majority of experienced folks here have spoken to the rarity of tweeter damage and potential sonic benefits to the polyswitch elimination. Right now, I am swayed by their collective experience. No one seems to be saying "hey, you are 50/50 for blowing your speakers". I have an e-mail in to Polk about the new polyswitches. It would be great if I could try it both ways and may do it if I get really ambitious!! Thanks for your concern.:)

[MillerLiteScott]

I removed mine. However I can not do a direct comparison because I changed the tweeters, caps and resisters. I certainly am enjoying an improvement. I feel my tweeters are safe barring a freak accidental burst of power.

[read-alot]

The ones (polyswitches) that were in my SRS were without a doubt detrimental to overall performance and I'll leave them out....peroid.

[Lasareath]

Ben,

I understand your concern for speaker protection, but the majority of experienced folks here have spoken to the rarity of tweeter damage and potential sonic benefits to the polyswitch elimination. Right now, I am swayed by their collective experience. No one seems to be saying "hey, you are 50/50 for blowing your speakers". I have an e-mail in to Polk about the new polyswitches. It would be great if I could try it both ways and may do it if I get really ambitious!! Thanks for your concern.:)

Analog97, I removed my polys as well on my crossovers. The main thing is to know what are the limits of your system and not go beyond that and your tweeters should be fine.

I am using an Onkyo Receiver that is pre-outing to two Carver TFM-35X's. I know that on the volume control I should not go beyond 80 to 84.

One Day when an old friend was over I put on some metallica and cranked it to 90. The next week I noticed my left tweeters sounding funny. I fried two of them.

So figure out your limits and don't go beyond it.

Sal

[analog97]

The Sonicaps arrived today. I tested the caps with my DMM and found:

1. All the 12 uf caps measured 12.5 (very tight, maybe +/- .1 uf)
2. The 13.5 uf caps measured 13.5 (+/- nothing!!)
3. The .22 uf caps measured .21 (both)

What I was curious about is that the 12 uf caps were a tad high. Does anyone see any issues before proceeding? TIA. :)

[schwarcw]

Larry,

That's less than 1%, well within tolerance, the caps were probably spec'ed by Polk at +/- 10%. I personally don't see an issue. But heck, I'm no expert.

If you have the yellow TI caps made in Mexico, the Sonicaps should sound better.

[analog97]

I don't know what i have. I may pull one out and take a peek sometime soon. Looks like 9 hex screws on that metal panel. Hopefully, the wires are long enough for me to get a good look. Everything is a mystery. Where is Tesla when we need him??

[schwarcw]

The wires should be long enough. You could also pop out the passive radiator and still your whole head in there LOL!

[F1nut]

They are within 5% tolerance, which is much better than the +/-10% on the stock caps. You're golden.

[analog97]

Thanks to F1. Good to know I'm "golden". But, the obvious thing threw me. The 6, 12uf caps all measured 12.5uf, which is about 5% off. The 13.5's were dead-on and the .22's were very close as well. That's my point. Carl was right when he said the Sonicaps were huge!! The biggest part of this re-do seems to be the layout to accomodate the big-ass caps. Both Carl and Joe offered help. Ain't that super!! You gents have been great. Thanks for all the help.:)

[F1nut]

Sorry Analog97, you're right it is 5%, not 1%. I wasn't thinking clearly when I posted. Anyway, this is from Sonic Craft's site in reference to Sonicaps, "Tolerance is better than 5%. Custom values and tighter tolerances are available." So, as you can see all is well and you're still golden.

[schwarcw]

OOPS! I thought the .1 uF was the amount, like F1 said it's still within 5%. It is a little odd that they were all off by 0.5 uF and the others were did on. Send Jeff at Soniccraft an email and ask him for his thoughts. I'd say call him, but be prepared to be on the phone a while. He love's his products and will talk to you at length. Great guy!

[analog97]

Good idea, Carl. As I said, the observation that all 6, 12 uf caps were 12.5 threw me. I'll call when I return from the "Windy City".....

[F1nut]

There's really nothing to ask about. Sonicaps are spec'd to +/-5% tolerance or better. So, you got some the were +5% and some that were better. End of story. If you had requested tighter tolerances and matching for all the caps you ordered, they would have done so.

[schwarcw]

There's really nothing to ask about. Sonicaps are spec'd to +/-5% tolerance or better. So, you got some the were +5% and some that were better. End of story. If you had requested tighter tolerances and matching for all the caps you ordered, they would have done so.

You're right Jesse, Larry has nothing to worry about. The caps are within spec and will sound just fine. It's just interesting that 6 - 12 uF caps are all exactly 0.5 uF over the 12 uF value, and all the other caps are dead on the value. Just interesting.

Carl

[analog97]

OK, you are right. I will not do anything except proceed and enjoy these magnificent speakers. Regards and I'll 'just do it'....

[hearingimpared]

Sorry boys I've on Mars the past few days. Larry it looks to me from reading these posts that you are good to go.

A couple of things however. I strongly recommend not changing or upgrading the SDA cable socket. I was going to do the upgrade that Darqueknight did on his SDAs and F1nut recommended that I didn't . . . the reason . . . there may come an time when I need to use an AI-1 cable due to some new amps I may purchase down the line. He also advised that the stock AI-1 sounded better to him than any home made version.

I'm glad I took his advise as I am purchasing an amp that is a dual mono block design that CANNOT be strapped. I also am getting my stock AI - 1 cable back.

The other thing I did was to upgrade the stock 5 way binding posts to Cardas posts. I can't say that I know for a fact that they made a sonic improvement. I can say I get and excellent electrical connection and they definitely bring the value of my 1.2 TLs up and they look damned good.

Have at it my friend and if you get stuck, you have my phone number. Oh yeah one more thing, don't be suprised if they take longer than predicted to burnin. Mine were predicted to burnin in 200 hours. At 340 hours I was panicking because they sounded so shrill but the magic point was about 345 hours and oh baby did they start to sing and give me lots of woodies.

[heiney9]

OK, you are right. I will not do anything except proceed and enjoy these magnificent speakers. Regards and I'll 'just do it'....

Get to it!! :p, Just remember it takes quite some time to get the new parts broken in so be patient and if you don't have the RD0 silk replacement tweets consider those as the final tweak. Then the transformation will be complete

H9

[heiney9]

and give me lots of woodies.

TMI, bro!!!:p:D

[hearingimpared]

Get to it!! :p, Just remember it takes quite some time to get the new parts broken in so be patient and if you don't have the RD0 silk replacement tweets consider those as the final tweak. Then the transformation will be complete

H9

I thought the RD0198s were already in place! For me they were the first upgrade. Whichever way you go on this you are definitely on the right track.

[hearingimpared]

TMI, bro!!!:p:D

Okay I'll clean it up, how about unlimited goosebumps and an infinite amount of rush tears!!!