Monitor 7C recap Questions

telemike

Thinking about recapping my Monitor 7C's with SL2000

I see the schematic call for a 34 uf cap on the midbass driver. I only see 33 uf for sale. I looked at parts express and ebay. Nada. Where can I find a 34 uf at?

The 12 uf mylar cap should be ok right? Mylar doesn't degrade like elctrolytics.

Suggestions? I am on a budget so no audiophile caps.

Faustin

You should replace all of the caps at the same time. Many people including myself have used a 33 uf cap in place of the 34 and have not noticed any difference in the sound. The 33 is also a tighter tolerance than the original 34's. If you are on a budget, you can use the Dayton 12 uf that has a 1% +- tolerance that is only a couple of dollars more than the 5% tolerance cap.

telemike

What about non polarized electrolytics? Are those better to use?

telemike

Easy Runnin

http://www.soniccraft.com/product_info.php/gen-sonicap-34-uf-200vdc-p-4638

bryantspaint

I used these Erse on all caps
Mills on resistors

bryantspaint

here http://www.erseaudio.com/Products/PulseX630v/MPX63-03-33-0

telemike

Ouch! That's $44 for two caps. I don't want to sink that much money into these.

Thinking:


Dayton Audio DMPC-12 12uF 250V Polypropylene Capacitor @ $5.24 ea

33uF 100V Electrolytic Non-Polarized Crossover Capacitor @ $0.98

maybe:

Audyn Cap Q4 33uF 400V MKP Metalized Polypropylene Foil Crossover Capacitor @ $9.25 ea

Faustin

Here is my suggestion for budget caps:

http://www.parts-express.com/dayton-audio-dmpc-33-33uf-250v-polypropylene-capacitor--027-441

http://www.parts-express.com/dayton-audio-pmpc-12-12uf-250v-precision-audio-capacitor--027-246

You will have $40 into the caps and just need the resistors

bryantspaint

the http://www.erseaudio.com/Products/PulseX630v/MPX63-03-33-0
are 10 bucks each, best budget caps on the market

telemike

I could also parallel two 17 uf caps as well to make 34 uf

Faustin

telemike wrote: »

I could also parallel two 17 uf caps as well to make 34 uf

You could use the 2 17 uf caps, but keep in mind that the new caps are quite a bit larger than the old ones and you may run out of real estate on the board.

blackwaterrisin

Faustin wrote: »

Here is my suggestion for budget caps:

http://www.parts-express.com/dayton-audio-dmpc-33-33uf-250v-polypropylene-capacitor--027-441

http://www.parts-express.com/dayton-audio-pmpc-12-12uf-250v-precision-audio-capacitor--027-246

You will have $40 into the caps and just need the resistors

Hello everybody.
first post on the forums although I've lurked and read for a while.
I'm about to dive into this with minimal electronic experience.
Luckily I have a friend with know-how to assist in the actual rebuilding of the x over.
I already have 2 each of the above caps in my cart. now which resistors. does it just need to be a Mills 2ohm 12V??? can someone help me complete my Parts Express shopping list?

here's pics of my xover. the standard 7C I presume

blackwaterrisin

I also went ahead and got a pair of RDO194s.. I've had my 7s for about 3 years and I always thought the highs were a bit "chirpy",although they still sounded really nice to me.

I figured it was just the SL2000s or I needed the x-over upgrade.
I purchased a Rogue Audio Sphinx a few weeks ago and it plays real nice with the Monitors but it sounded like the highs were a little more harsh than before so
I took the plunge and ripped into my Polks.

pkquat

If you dig around the forum you will find many posts about the SL2000's being bright around the 13kHz range if I recall. Some people don't mind, others hate them. From many posts here, the RDO194's are much better than the SL2000's overall. If you can change your order, the RDO198's are said to be even better, but require a different capacitor for the crossover. This is referred to as a "TL" mod. "TL" referring to the Tri-Laminate SL3000 tweeter that required slightly different crossover components.

blackwaterrisin

hmmm...yes I could do that. I doubt the tweets have shipped yet.
the RDO 198s are the same size as the 194s,correct? I may only have to adjust the mounting holes?
Is the TL mod significantly harder to do? and if not,what are quality budget caps and resistors for the TL mod?
I'm gonna do some readin' but any suggestions would be helpful.

blackwaterrisin

And does Polk still sell the tweets direct? because it seems like the only vendors are speakerex.com and midwestspeakerrepair.com... I went with speakerex.

pkquat

The RDO198, RDO194, SL2000, SL2500, SL3000 are all physically interchangeable. The older peerless tweeters have a different faceplate size and mounting holes. You can order tweeters directly from polk audio customer service. Mention you are a forum member and get a discount.

From what I have gathered "westmassguy" is one of the, or "the", crossover expert. After some poking around the crossover upgrade may not be super simple. You might be able to add cap, or you might need to find crossovers from a 7C to start with to do the upgrade.

Sonic Craft appear to be the ideal caps, but Clarity and Daytons are budget options. These two threads should help.
http://forum.polkaudio.com/discussion/172230/monitor-7s-recapped-wow-blown-away
http://forum.polkaudio.com/discussion/171820/sl2500-rdo-198-original-vs-series-2-mw6502s

This thread has the wiring schematics. (It was a sticky, but something happened. I should be a sticky again soon.) M7_rev is for the RDO194. M7_rev2 is for the RDO198.
http://forum.polkaudio.com/discussion/38755/polk-audio-speaker-wiring-schematics-more-all-models-except-sda

As long as you are at it. Its best to "powergrab" the magnets on the MW's. They can become unglued with age and a bump. This thread has some good pictures and explanation.
http://forum.polkaudio.com/discussion/171529/polk-10b-monitors-crossovers-and-tweeter-upgrades

Hurricane nuts for the driver screws are also a good idea. Or you can go deluxe with "Larry's rings". A search on "Larry's rings" will give you more info on that.

blackwaterrisin

well im sticking with the RDO 194s because I can have them by the end of the week.
so now I'm still looking for resistor suggestions.

pitdogg2

blackwaterrisin wrote: »

well im sticking with the RDO 194s because I can have them by the end of the week.
so now I'm still looking for resistor suggestions.

Are you doing these yourself? If I was you I stick with the 194's from Polk at 48$ each. you need to get some Mills resistors 2ohm but go up to 12watt for the added ins. instead of the 5 watt you have in there now. you can also do away with the polyswitch if you know how to keep the volume under control. You will need another 2 resistors in .5 ohm again 12 watt. The poly switches do wear out over time with many trips they just start tripping needlessly that is why most take them out BUT you will toast tweeters if you are not careful good clean power and you should be ok.

The TL mode is not as simple as a cap switch

PKquat knows just enough to be dangerous he/she has the right idea BUT we do not know YOUR capabilities soldering and reading schematics and understanding what needs to be done for the TL mode to use the RDO-198. Get some film caps and stay away from the electrolytic's it just does not make sense to put them back into the circuit.

pitdogg2

the poly is at PS1 little yellow thing

blackwaterrisin

yes. what i read about the TL mod was a little more intimidating than the standard cap replacement and the RDO194s are in stock now and shipped.

what exactly do you mean by "keep the volume under control"?
if that means listening at low volumes only,it's probably not a realistic option for me
can I just replace the polyswitch?

pitdogg2

you can replace the polyswitch get the value and see if parts express has one in stock the same value or try calling polk CS to see if they will send you a set..What is meant by volume under control is IF you hear any distortion,musical compression or are well past 1/2 way on the value knob you are more than likely throwing square waves at the XO which is how you toast drivers. Look you can only get so much out of any set of speakers and trying to push them past their limit will ALWAYS have repercussions like it or not.

Not to mention pushing any amp or receiver past its limits also has some very negative repercussions.

blackwaterrisin

pkquat wrote: »

As long as you are at it. Its best to "powergrab" the magnets on the MW's. They can become unglued with age and a bump. This thread has some good pictures and explanation.
http://forum.polkaudio.com/discussion/171529/polk-10b-monitors-crossovers-and-tweeter-upgrades

and thanks for that. I looked at a couple threads on "gluing magnets" but that's what I needed to see. I may just send the xovers off to westmassguy.
as i said before,I have a friend with some experience to help but it may just be best to leave it to the experts

blackwaterrisin

pitdogg2 wrote: »

you can replace the polyswitch get the value and see if parts express has one in stock the same value or try calling polk CS to see if they will send you a set..What is meant by volume under control is IF you hear any distortion,musical compression or are well past 1/2 way on the value knob you are more than likely throwing square waves at the XO which is how you toast drivers. Look you can only get so much out of any set of speakers and trying to push them past their limit will ALWAYS have repercussions like it or not.

Not to mention pushing any amp or receiver past its limits also has some very negative repercussions.

ok got ya. I don't ever play it THAT loud. about 10 or 11 oclock is about the max I can endure for any duration on my rogue sphinx. I just wanted to make sure I wasn't risking damage to a tweet with these mods just from standard listening.

pitdogg2

blackwaterrisin wrote: »

I just wanted to make sure I wasn't risking damage to a tweet with these mods just from standard listening.

No not a chance of that.

adam2434

Thought I would add some observations to this thread.

I’ve had 7C’s in my garage for several years now and decided to work on the crossovers a couple weeks ago. I installed the RDO tweeters a couple years ago.

The 7C’s have always sounded a bit dull and muddy, both in the garage and in the unfinished portion of my basement. My hope was that the crossover refresh might liven up the highs a bit, and at least bring them back to factory performance.

I did not want to spend a lot on the parts, so I went with a Dayton Precision 12 uF, Parts Express NPE 33 uF, and a Mills 2.0 ohm. I removed the polyswitch and used a piece of lead for a jumper, knowing that this should boost the tweeter output a bit (which I thought might help with my perception of dullness).

So, I finished the work and put them back in the garage, fired them up and was quite shocked at how different they sounded. They had so much more detail and life – the opposite of dull and muddy. However, they had too much of a good thing and did not sound balanced. Because the highs were more prominent, the bass sounded weak.

I decided to remove the polyswitch jumper and install a Mills 0.5 ohm (which I happened to have left over from another project). With the 0.5 ohm in place of the polyswitch, I feel the sound is balanced and improved vs. the stock parts. The speakers have more life, energy, and clarity. They definitely responded to the new crossover parts.

[Deleted User]

If you're sending your crossovers to wmg, he can provide you with the correct quality parts too. And good binding post, etc. to save you questioning, guessing, multiple shipping costs, etc. as well.