Monitor 12S2 crossover rebuild suggestions

jmitchnh

I am making plans for a crossover rebuild of my Monitor 12 S2s and want to get your thoughts on parts and a bit of re-engineering.

1.I would like to remove the protection circuit (a RDE 90 polyswitch and 4.2uf cap in parallel) as I listen at low to moderate levels and use high quality amplification.

2.There are two 12uf caps (one in parallel with a 2 ohm / 5 W resistor) in series with the tweeter. I?m thinking two 12uf Clarity PX caps and a Mills resistor.

3.There is a 16.4uf cap in parallel with the four mids. From reading numerous threads, I understand that the quality of this cap is not as important to sound quality as those in the tweeter circuit. Any suggestions for what to use here?

Once the crossovers are done, I will be upgrading the tweeters to the RDO 198-1s. Any other suggestions/tweaks?

thsmith

Dynamat the baskets and spike your 12s.

drumminman

thsmith wrote: »

Dynamat the baskets and spike your 12s.

What he said + a little Black Hole 5 on the inside of back panel behind MW's and tweeters. Also, new gaskets (from Brgman or Armaflex from Home Depot) for MW's and Tweeters, and Hurricane nuts w/socket head cap screws for all drivers.

jmitchnh

Ordered components today. Going with Clarity Cap PX for the two 12uf and a Mundorf MOX 2.2 ohm resistor in the tweeter circuit. Using a Bennic XPP in the mid/bass circuit. As funds are an issue, trying to get best bang for the buck. Curious to see what my $55 gets me in terms of sound improvement. Next will be the RDOs and then cabinet mods. I'll keep you all posted.

jmitchnh

Finished the x-overs last evening. While I had the drivers out I decided to follow thsmiths advice and Dynamat the baskets. I must admit that at first I doubted this would make much, if any, difference. However, it is amazing how an untreated basket "rings" when you tap it. Once Dynamatted, it makes a nice dull "thud" which I'm sure must add to the sonice accuracy of the drivers.

In my rush and excitement, I neglected to take a "before" pic so I can't provide the dramatic side by side comparison, but here's a pic of the same 12uf cap with 2 ohm resistor, stock (bottom) vs replacement (top)

Finally, the finished crossover:

So how does it sound? It only has a few hours on it but already I can hear much more hidden detail and a much wider and open soundstage. The tweeters still sound a bit flat to me. I'm wondering if they may be at less than 100% and hoping that the next upgrade, RDO 198-1 tweeters, will open up the top end. Anyway, for less than $100 (caps, resistors and Dynamat) it sounds much better and a lot fun to do!