Modding RT25i crossover ?

heiney9

I've decided to mod the x-overs in my wonderful sounding Polk RT25i's. I have been wanting to do this for awhile now.

For the tweeter section they use an 8uF electrolytic and a 1.0uF mylar in parallel and a 2 ohm resistor in series.

I am having a heck of a time finding a 9uF capacitor other than Sonicap Gen I which makes the exact value. I have done Sonicaps before several times, so I was looking for something different this time.

As always these are in rotation in a secondary rig (might make a 3rd rig one day) so they don't get a lot of use. The idea is to keep the costs down. I'd like to keep the entire project to about $50.

Resistors will be Mills 5 watt 2.0 and 3.5 ohm $6 each crossover
27uF Low pass cap will be Solen PB $11 each crossover

I have some options as far as caps for the tweeter.

1. 9uF Sonicap Gen I $19.01 each crossover (over budget)
2. 3.3uF & 5.6uF Mundorf M-Cap Evo $11.23 each crossover
3. 2.2uF & 6.8uF Mundorf M-Cap Evo $11.88 each crossover
4. same values as above Mundorf M-Cap Evo oil $20.20 each crossover (over budget)
5. same values as above Clarity Cap ESA $23.00 each crossover (over budget)
6. same values as above Clarity Cap PX $11.00 each crossover

I am open to other suggestions. I've never used Mundorf and I know some have and sware by them. I am a big fan of Clarity Caps and already use the PX series in my 5B's. This is where I'm leaning, but I can be convinced to go another route.

So let's discuss.

H9

heiney9

Now I remember why I hate doing crossover mods..................can't get ALL the stuff from one website....lol.

Madisound has 9.0uF PX and ESA Clarity Caps, but don't carry the 27uF Solen Cap (only 25uF cap). Other places have the 27uF Solen but don't carry a 9.0uF cap.

This means paying shipping twice.

Really irritating.

westmassguy

9uf Clarity PX for the Hi-Pass and 12uf + 15uf Clarity PX for the Lo-Pass. Little over budget, but much better than Solens.

lightman1

Where are you gonna mount the tube sockets?
I suggest on the top for heat dissipation.
Put up your dukes Brock!

Nightfall

lightman1 wrote: »

Where are you gonna mount the tube sockets?
I suggest on the top for heat dissipation.
Put up your dukes Brock!

Too much vibration to mount tubes directly in/on a pair of speakers, quit yer trolling!

lightman1

Never

F1nut

I LOVE Mundorf caps in electronics, but I've never used them in a crossover. That said, I think they'd be worth trying.

heiney9

Yeah, been wanting to try Mundorf's in something. The oil ones have me a bit intrigued. I need to pull the x-overs again and familiarize myself with the real estate available to make all this work.

Size does matter and I might be limited in that area as I'm not wanting to turn this into a big custom project. It seems like the reason I abandoned this before was cap size vs. the terminal cup and opening......lol

Just a bit irritated I can't get the correct values of all the caps and resistors from one vendor.

H9

soundfreak1

Used the munforf's in my 5jr+'s and worked fine. BTW if you would like I have a pair (I believe) of rt25 xovers you can have if you want to keep the originals intact.

heiney9

Really, soundfreak1? That would be great. Are yours the RT25i or just RT25?

H9

soundfreak1

Just the reg rt's bought them at a garage sale some years ago when I had a pair in a 5.1 system. The cabs were for fobar I needed 1 driver for my good pair and still have all the others and the xovers I think just need to open the box and see them again. Pulled them out of the cabs and packed them away. Also have 1 driver and 2 tweets as I remember.

soundfreak1

yep just found the box! 1 mw5522 driver, 2 sl5507 tweets and 2 complete original xovers. Also (forgot I hade these) 2 vifa 804 tweets from a pair of time frames 450's I think.

soundfreak1

I love finding sealed boxes of stuff I forgot I had. It's like Christmas all over again. Too bad I can't use them. LOL

soundfreak1

Heiney9, I believe they are the same? Is it just the cabinets that differentiate them?

heiney9

I know what you mean, I found a pair of M5 passives I forgot I had as well as recently hooking up a pair of Pinnacle speaker's I haven't listened to in quite sometime.

Let me peak at the crossover to familiarize myself again and then I'll let you know if I want those.

H9

soundfreak1

No prob. Have no use for them. There here if...

heiney9

So, going through some old parts odds n ends boxes I found the caps I bought awhile ago for this upgrade. Clarity caps and Aeon caps for the low pass and Mills.

Soundfreak1 if you still have those crossovers and they need a home, I'll take them.

H9

soundfreak1

That can work. Pm me your info. No charge for the xovers just cover the ship. They should fit into the P.O. 10.00 box. I will check as I think I have one to test fit.