RTi8 XO Mod

curved

Starting the RTi8 XO mod.

C1-10uF 50v
C2- MET .22uF 100v J
C3- MET .22uF 100v J
C4- NP 12uF 50v
C5- NP 27uF 50v
R1- 5w 1ohm 3J
R2- 5w 6ohm 2J

Any recomendations? I was thinking about using Daytons....

curved

Option 1:
SoniCap Gen1
C1 - 10uF 200VDC - $18.50
C2 - .22uF 600VDC - $4.90
C3 - .22uF 600VDC - $4.90
C4 - 12uF 200VDC - $20.45
C5 - 27uF 200VDC - $28.60

Total = $77.35/speaker for Caps

curved

Option 2:
Dayton Polypropylene
C1 - 10uF - 250V
C2 - .22uF - 250V
C3 - .22uF - 250V
C4 - 12uF - 250V
C5 - 25uF - 250V

Total = $17.47/speaker

george daniel

Why are you upgrading them? I ask, because I did not think that they were that "old".If you plan to keep them for a long,long, time,,I would go with sonicaps,,otherwiseI think that I'd go with the dayton's from a price-performance ratio.On second thought,, go with the daytons or a reasonable facsimle thereof. Good luck.

curved

george daniel wrote: »

Why are you upgrading them? I ask, because I did not think that they were that "old".If you plan to keep them for a long,long, time,,I would go with sonicaps,,otherwiseI think that I'd go with the dayton's from a price-performance ratio.On second thought,, go with the daytons or a reasonable facsimle thereof. Good luck.

Upgrading for a couple of reasons:
1. I was watching the WI vs Iowa game and decided that I could do better things with my time.
2. Wife was sleeping
3. Song was sleeping
4. I want to see what these things are REALLY capable of:D

Polksaladanni

Hang loose for 2 more weeks curved. I just got a listen of my set and they are very nice. Although the RT55 kicked it's azz with more bass It's a very fine speaker and a looooong time last time keeper for me. ( I snagged em in cherry is why, RT's are black=bummer)

Howbout Ben and others chime in who have used various caps and their electrical theory more currently than I, before you or I go buying caps. I'm in it for the long run and saftey measures so, i'm doing it period. I'm an R&R man occasionally now. Haven't been professionally for 15yrs.

A light bulb went off though, but I can't remember or dig the college books out of the attic for maybe an answer. Since recapping the RTi6, RT55 and M4 I noticed this on both of the RT's. Both of the XO's had 50v caps for the LP and a 50v cap for the initial filter, at the xo slopes, for the HP. f Both used 100v caps (1 or 2 more) for the shaping of rest of the higher HP frqs. Aside from the obvious, of more protection for the easier to damage tweeter, both XO's had a 2 to 1 ratio difference in the cap voltage from LP to HP. The RT XO's are 12b to 18db 2nd order slopes.

That said, Polks have always been known for their great "presence" in the mid to let's say 5Khz range.( using #s only for a refernce point) I am wondering if that might be a good reference point for buying caps??? If you want them to keep that presence when recapping???

Say Dayton 250v for the OE-50v??? and Solen/Jantzen/Your Preference 400v to replace the OE-100v????

That's pretty much the way it worked out on the RT55. (It rules) But on the RTi6 I used a 400v Jansen on the LP and a 250 Dayton at the start of the slope of the HP.... I seems to be missing a little bit of bass and presence. Do they sound bad? No! But now I'm thinking it might have more "presence" if I had used matching 250v caps there. The M4 was a simple serial XO with same voltage caps HP&LP and, replaced with same voltage caps. (250v Daytons)

I know the are NonPolar caps and not 3pole power supply caps but, they are used in a variety of ways other than just XO's . I can't remember if the NP's store a little energy while they are being used as a XO,AC,DC,Line filter???

What do you guys think?

ben62670

george daniel wrote: »

Why are you upgrading them? I ask, because I did not think that they were that "old".If you plan to keep them for a long,long, time,,I would go with sonicaps,,otherwiseI think that I'd go with the dayton's from a price-performance ratio.On second thought,, go with the daytons or a reasonable facsimle thereof. Good luck.

Hey George. It's not that the caps are old. Many of the SDA caps are still in spec(all that I have tested were), but that the caps that were used are still the same mass produced caps that are used in many of the other Polk's since the SDA's, and monitors. Polkies are not like most others. We love our hobby, and modding makes sense. Kinda like cars. Most people just buy a car, and thats it. Some like to mod;) After doing mods on monitors, SDA's, and know LSI's I don't see any reason not to try modding RTi's if you plan to keep them.
Ben

mmadden28

curved wrote: »

Starting the RTi8 XO mod.

C1-10uF 50v
C2- MET .22uF 100v J
C3- MET .22uF 100v J
C4- NP 12uF 50v
C5- NP 27uF 50v
R1- 5w 1ohm 3J
R2- 5w 6ohm 2J

Any recomendations? I was thinking about using Daytons....

Mix it up--Sonicaps for the highs and Daytons for the lows.

Polksaladanni

Ben.

You've used many brands and voltages what do you think about the 2/1 voltage ratio?

You think it has any merit?

Paul

ben62670

Voltage in XO caps really doesn't have an effect here. Most aftermarket caps are 100v or better.

Polksaladanni

Yea, but look at the huge difference in size between the 250v Dayton and the 400v Jantzen. You think that might affect electron/ power flow?

Paul

Crap. The pic didn't upload.

Polksaladanni

curved wrote: »

Starting the RTi8 XO mod.

C1-10uF 50v
C2- MET .22uF 100v J
C3- MET .22uF 100v J
C4- NP 12uF 50v
C5- NP 27uF 50v
R1- 5w 1ohm 3J
R2- 5w 6ohm 2J

R1 is actually 1.3ohm and R2 is 6.2ohm. If you switch R's and don't get the right value it changes the whole works on the XO. Not necessarily for the better.

Here are the "working" voltages for a 5Watt audio resistor via Mr. Jantzen. I ****-umme he is using Vdc=1.7xVdc=Power/Watts (Non-EIR formula)

Click on: About metalized resistors pdf
http://www.jantzen-audio.com/html/resistors.html

Maybe don't replace the R's? They are Bennic 19ga NIWW's

Polksaladanni

Size comparison. Geez I'm an end-user idiot.

george daniel

ben62670 wrote: »

Hey George. It's not that the caps are old. Many of the SDA caps are still in spec(all that I have tested were), but that the caps that were used are still the same mass produced caps that are used in many of the other Polk's since the SDA's, and monitors. Polkies are not like most others. We love our hobby, and modding makes sense. Kinda like cars. Most people just buy a car, and thats it. Some like to mod;) After doing mods on monitors, SDA's, and know LSI's I don't see any reason not to try modding RTi's if you plan to keep them.
Ben

I hear you,,, I was gonna' suggest that he might want to entertain doing something else,,,but self control got the best of me. I guess that I'm old skool:(,,but if I'm gonna' crack em' open,,I'm putting in Sonicap/Mills,,given the current economic climate,I might have to wait a while,,, just my .02,, no offense intended to anyone. Let us know how they sound. Good luck.

curved

mmadden28 wrote: »

Mix it up--Sonicaps for the highs and Daytons for the lows.

That could also be an option. For the people who have used these caps, what were your feelings on them and what did you notice as far as sound characteristics, etc....

mmadden28

Here are at least three recent threads that are intertwined. Each involves mixing the caps in the Highs and Lows. Highs being more important to put the higher quality/price caps on.

http://www.polkaudio.com/forums/showthread.php?t=71515
Sonicaps and Daytons

http://www.polkaudio.com/forums/showthread.php?t=72273
Sonicaps and Solens

http://www.polkaudio.com/forums/showthread.php?t=73233
Sonicaps and Aeon

Lots of shootouts done-just search for 'shootout' to find some relevant threads if you want more reading.

curved

Well I finished the first speaker. I did the same mods as the A4. I just can't turn it up at all because the wife and child are sleeping. I'll take some pics on the 2nd xo and post them up.