RTi8 XO Mod (Complete)

johnchabin

Can't send a PM yet, but any more info on your parts list? Part numbers? Distributor?

Are you still happy with this mod?

Thanks!

johnchabin

Hi curved,

Does this look right?

Each RTi8:

C1-10uF - Dayton Prec. (PMPC-10 10uF 250V Precision Audio Capacitor, Parts Express P/N: 027-244)
C2- .22uF - Sonic Cap (Gen I, 0.22µF / 600VDC from Sonic Craft)
C3- .22uF - Sonic Cap (Gen I, 0.22µF / 600VDC from Sonic Craft)
C4- 12uF - Dayton Prec. (PMPC-12 12uF 250V Precision Audio Capacitor, Parts Express P/N: 027-246)
C5- 25uF - Dayton Prec. (PMPC-25 25uF 250V Precision Audio Capacitor, Parts Express P/N: 027-256)
R1- 1ohm - Mills (12W Non-Inductive Resistor, Parts Express P/N: 005-1)
R2- 6ohm - Mills (12W Non-Inductive Resistor, Parts Express P/N: 005-6)

Thanks!

polkfarmboy

man I should do this to my rti8

Is it easy to remove the part and send it to some one

Sherardp

Thinking of these for the Rti12s in my HT. Someone post a parts list so I can order. It will give me something to do over holiday break.

johnchabin

Here's my final parts list for the RTi8, nearly a copy of the one 'curved' used...

C1 Dayton PMPC-10 10uF 250V
C2 Sonicap Gen I 0.22µF / 600VDC
C3 Sonicap Gen I 0.22µF / 600VDC
C4 Dayton PMPC-12 12uF 250V
C5 Dayton PMPC-25 25uF 250V
R1 Mills MRA-12, 12w 1.2 Ohm
R2 Mills MRA-12, 12w 6.2 Ohm

The only difference from the 'curved' parts is I am using 1.2 Ohm (R1) and 6.2 Ohm (R2) resistors to more closely match the original parts. 'curved' used 1 Ohm and 6 Ohm. SonicCraft has a 20% off sale until December 17th, so I wanted to get this done.

I considered going all Sonicap, but couldn't justify the added cost, so just using Sonicap for the HF and Dayton for the LF.

johnchabin

Update: got the parts and the Dayton caps don't fit the through-holes on the circuit board. I'm going to get Sonicap Gen I all around, which have smaller and longer leads.

The factory parts were not too difficult to remove, but I've done a lot of board work in the past. I've always found it helpful to melt a bit of new solder into the old prior to using solder-wick. Seems to make it melt and flow better.

It was interesting that the circuit board is stamped 1.8 Ohm at R1, but the factory resistor I removed is 1.3 Ohm. I wonder why.

johnchabin

Done. The Sonicap 10, 12, and 27µF caps also had the larger leads, but I worked it out.

So, my final parts list for each speaker was:

C1 Sonicap Gen I 10µF / 200VDC
C2 Sonicap Gen I 0.22µF / 600VDC
C3 Sonicap Gen I 0.22µF / 600VDC
C4 Sonicap Gen I 12µF / 200VDC
C5 Sonicap Gen I 27µF / 200VDC
R1 Mills MRA-12, 12w 1.2 Ohm
R2 Mills MRA-12, 12w 6.2 Ohm

johnchabin

Well, I may be the only one interested, but there is a noticeable improvement. I really like how they sound now - mids are much clearer and no longer mushy or muddy. More than 50 hours on them and they have never sounded nearly this good.

FWIW, I changed the crossover frequency on my receiver (VSX-94TXH) from 80 to 50Hz. Much better with these fronts.

SonicCraft was really good to work with. I will call them again when I upgrade my center...

Tungx2

Hello,

I've got RTi8 as well, actually 4 in total, but I'm only using a pair, the other pair is still in its box.

Anyways, I'm wondering what is the damage to the wallet? how much did it cost to get those components for each speaker?
Thanks in advance

adam2434

Hi, been a while since I’ve posted here.

Recently picked up a set of RTi8’s for a modest, secondary system.

I found them too bright for music, so after some research, experimented with Mills 12W resistors between the top and bottom (+) binding posts, adding series resistance before the tweeter crossover. I found that 1.0 Ohm was too much and 0.5 Ohm is about right for my ears. I use LS90’s in the main system, so that’s my primary reference.

From what I’ve read, adding series resistance will lower the crossover point, and also will not provide the same attenuation at all frequencies, depending on the impedance curve of the tweeter. Therefore, I don’t think that adding a series resistor is the “right” or “best” way to attenuate the tweeter.

So, I’m curious as to what the resistor is doing to the frequency response and crossover point. I guess this could be modeled or measured if one had the right input data and measurement equipment, right?

As a side note - owning LS90’s, vintage Monitor 7’s and 5’s, older RTxxxi, newer Monitors - the RTi8s are the first Polks I’ve owned that I would consider excessively bright, so I wonder what Polk was aiming for with these. Sizzle in the HT showrooms?