Monitor 10 crossover question w/ pic

bwdst3

Thinking of recapping my 10's. I found the schematics page and I don't really understand how to read it but I can match the values to what I see on the actual crossover. Whats the big yellow one? Is that also a 12uF value and why does it look so different than the blue 12uF cap? Thanks for looking.

westmassguy

The blue caps are Non-Polarized Electrolytics. The yellow cap is Mylar. Electrolytics are much smaller than Film Caps.
You'll want to replace all the caps with Metalized Polypropylene caps for the best sound. In addition, the Sand-Cast Resistors should be replaced with Mills MRA-12, or Mundorf Mox, Audio Grade Resistors. While you're at it, replace the little blue Polyswitch with a .5 ohm resistor, the same type as the others.

bwdst3

Thanks for the quick reply! Very helpful.

Msabot1

The yellow one is what is known as a axial capacitor. They are used in Xover networks that do not require tough requirements. No set value...can go between about.47-to 1kuf. They are aluminum electrolytic.

westmassguy

Msabot1 wrote: »

The yellow one is what is known as a axial capacitor. They are used in Xover networks that do not require tough requirements. No set value...can go between about.47-to 1kuf. They are aluminum electrolytic.

Axial is the mounting style, not the type of capacitor. The NP Electrolytics are also Axial mount. The Yellow cap is a Mylar Film Cap, not an Aluminum Electrolytic.

StantonZ

I'll second replacing the polyswitch with a .5 Ohm resister (Mills type): it made a huge difference on my top end since my PS was so far out of spec (>1 Ohm).

pitdogg2

westmassguy wrote: »

Axial is the mounting style, not the type of capacitor. The NP Electrolytics are also Axial mount. The Yellow cap is a Mylar Film Cap, not an Aluminum Electrolytic.

+1 cut one open you'll see lot and lots of mylar. you will not see any aluminum.

bwdst3

Thanks for the help. I'm listening now to the freshly recapped 10's and they sound incredible. Well worth the very little effort it took.

StantonZ

Good to hear! I have to admit: once I did it, I wondered why I had waited so long (of course the answer was $$).

westmassguy

bwdst3 wrote: »

Thanks for the help. I'm listening now to the freshly recapped 10's and they sound incredible. Well worth the very little effort it took.

Awesome, enjoy them!

StantonZ

kevintomb wrote: »

In what way did it change the top end?
Would it be just as good simply bypassing the Poly Switch with wire ?

It "opens up" the top end (e.g. higher PS resistance was obviously attenuating upper frequencies). Replacing the PS with a wire (which I considered) would probably make it TOO bright, in addition to removing any sort of (tweeter) protection in the event of a surge.

westmassguy

Polyswitches are a know issue with the older Polks. Their resistance is inconsistent even when new. Once tripped, their resistance changes, and they can introduce distortion in the signal. They are not precision devices by any stretch of the imagination. Polk even tried pre-conditioning them so their resistance would be consistent. Replacing them with a wire jumper will result in a higher tweeter output, and a "hot" or overly bright top end. Most replace the switch with a .5 ohm resistor, although some use a .2-.3 ohm as well. All depends on your particular taste.

westmassguy

kevintomb wrote: »

Gotcha....I tried simply jumper bypassing it and it did sound clearer, and with a bit too much treble, but I think it has a tad too much as is though.

That 12.5 khz bump kinda annoys me on my Tweeters, and over the years, I am not sure if I am imagining it, but it seems worse now.

I might even try a 1-2 ohm resistor.

My old drivers and crossover are being used in a project I am undertaking for a friend, mainly just something to do. We are keeping the original baffle look of the 3 drivers, but on a short baffle about 22 inches high.

Literally almost just cutting the RTA11t in half sorta, but made with new wood etc.

It will be about the width of an old RTA8t, but only 22" high, and with the original 2 woofers and tweeter. WE realize it will limit the bass a good bit, but he has VERY limited room and a sub already so none of that will truly matter.

Kinda the look of a 5jr+, but instead of the passive radiator it will be 2 woofers with the tweet centered between them.

Not sure if we are gonna load it acoustic suspension or TRY one passive radiator.

I would go ported, not PR. I have the TS Parameters for most of the older drivers. Just punch them into WinISD or Bass Box Pro.
As for the tweeters, there's really nothing you can do with the SL1000 or SL2000, other than a notch filter, but you're way better off with RDO-194s or even 198s if you do the TL Mod.

westmassguy

kevintomb wrote: »

Ya good idea. I think the passive radiators would be tuned "Too low" as they are tuned to something in the mid 30's I think from memory.

Acoustic suspension will really raise the cutoff frequency.

Hey If I give you the dimensions, would you mind modeling it for me? I mean if you have time. Due to uh recent comp crash and getting a new one, I no longer have access to any of my old stuff. Long story again....lol.

Yes we realize the new tweeters are better, but he kinda wants to not spend much. I have the 6 drivers and crossover, he has a lot of wood. The original cabinets were water damaged, sitting on an area that got mildly flooded.

The drivers are still like new, no rust, mold or ANYTHING wrong. The water merely got into the particle board, and about a foot of the bottom was all swollen and useless.

PM me or contact me via my website. I'll see what I can do

TennMan

kevintomb wrote: »

Ya good idea. I think the passive radiators would be tuned "Too low" as they are tuned to something in the mid 30's I think from memory.

Acoustic suspension will really raise the cutoff frequency.

Hey If I give you the dimensions, would you mind modeling it for me? I mean if you have time. Due to uh recent comp crash and getting a new one, I no longer have access to any of my old stuff. Long story again....lol.

Yes we realize the new tweeters are better, but he kinda wants to not spend much. I have the 6 drivers and crossover, he has a lot of wood. The original cabinets were water damaged, sitting on an area that got mildly flooded.

The drivers are still like new, no rust, mold or ANYTHING wrong. The water merely got into the particle board, and about a foot of the bottom was all swollen and useless.

What is your technique for cutting and recessing the holes for the drivers?

westmassguy

On my Center Channel Project, I used a 6 1/8" hole saw, and 1/2" rabbeting bit

TennMan

westmassguy wrote: »

On my Center Channel Project, I used a 6 1/8" hole saw, and 1/2" rabbeting bit

Thanks David. I have visions of building a 2B cabinet with the wide spacing of the CRS+ but it's probably just a pipe dream. I doubt I have the woodworking skills to pull it off.

westmassguy

TennMan wrote: »

Thanks David. I have visions of building a 2B cabinet with the wide spacing of the CRS+ but it's probably just a pipe dream. I doubt I have the woodworking skills to pull it off.

Another Franken-Polk Ronnie? Actually, not a bad idea with the height restrictions you have.

TennMan

westmassguy wrote: »

Another Franken-Polk Ronnie? Actually, not a bad idea with the height restrictions you have.

Yea, I like to experiment as long as I can do it without damaging any parts and I can revert back to a stock configuration. Actually I think a cabinet with the same wide MW spacing and the same tweeter location as the CRS+, while maintaining the same cabinet volume as the 2B, might be the ultimate 2BTL design. I don't have the tools and woodworking skills to do it but I know someone who does. I've just not had the opportunity to talk to him about it. I expect it will be cost prohibitive for experimenting purposes to pay someone to do it but you don't know until you ask.

westmassguy

TennMan wrote: »

Yea, I like to experiment as long as I can do it without damaging any parts and I can revert back to a stock configuration. Actually I think a cabinet with the same wide MW spacing and the same tweeter location as the CRS+, while maintaining the same cabinet volume as the 2B, might be the ultimate 2BTL design. I don't have the tools and woodworking skills to do it but I know someone who does. I've just not had the opportunity to talk to him about it. I expect it will be cost prohibitive for experimenting purposes to pay someone to do it but you don't know until you ask.

You can actually build it better, all MDF, not particle board, lot's of internal bracing, and unlimited choice of cabinet finish and grill work. Sounds like a lot of fun actually.

westmassguy

kevintomb wrote: »

I have spent the last few days, literally scouring the forum, but can not find any actual "User measured" frequency response graphs, of any of our vintage drivers/

Has anyone actually measured the drivers, "Free" of the crossover, to get the actual undoctored response and Impedance graphs?

I doubt you'll find that information anywhere, other than the secret underground lair, located below Polk headquarters in Baltimore.
Even the T/S parameters I have for the older drivers don't have the SPLs listed.