M4.6 SII five way post upgrade?

babyjames

Howdy! Newbie around here, first Polk loudspeakers. Just getting back into hifi after a number of years, and on a very limited budget. Used to be waist deep in gear, but that is no longer the case....

So I picked up these Monitor 4.6's even though I told myself on the way over to check them out I'd pass if they only had the cheesball pinchey connectors. Lied to myself AGAIN!

I'm thinking buy crossovers from some fives and cut a bigger hole in the cabs? Thoughts? Any other mods popular for this model? I'm assuming there is little or no internal bracing? Just got 'em a couple days ago and haven't had a chance to open them up yet. Any and all input welcome.

Cheers!

F1nut

I'm thinking buy crossovers from some fives

Huh?

teekay0007

F1nut wrote: »

Huh?

I think he means he's thinking of buying some crossovers (attached to the binding post cups) from some Monitor 5s. Then, he wants to cut bigger holes in the Monitor 4.6 cabs for the M5 binding post cups to fit into them, thereby "upgrading" from the spring-loaded speaker wire clips of the Monitor 4.6s to the 5-way binding posts of the Monitor 5s.

westmassguy

babyjames wrote: »

Howdy! Newbie around here, first Polk loudspeakers. Just getting back into hifi after a number of years, and on a very limited budget. Used to be waist deep in gear, but that is no longer the case....

So I picked up these Monitor 4.6's even though I told myself on the way over to check them out I'd pass if they only had the cheesball pinchey connectors. Lied to myself AGAIN!

I'm thinking buy crossovers from some fives and cut a bigger hole in the cabs? Thoughts? Any other mods popular for this model? I'm assuming there is little or no internal bracing? Just got 'em a couple days ago and haven't had a chance to open them up yet. Any and all input welcome.

Cheers!

I own several pairs of 4.6s, and they're very fine speakers, similar to the 5jrs. I'll address the upgrades individually.
Binding Posts: http://www.parts-express.com/round-speaker-terminal-cup-2-7-8-gold-banana-binding-post--260-283
These should fit exactly, and the solder tabs on the back align with the solder tabs on the crossovers. Double check the opening size.
The crossover is relatively simple. The Hi-Pass is second order, and the Lo-Pass is 1st order. The phase is reversed on the Hi-Pass.
You will need two 13.5uf capacitors and two .5 ohm resistors to upgrade the crossover. I used Sonicap Metalized Polypropylene Caps, and Mills MRA-12 resistors. The new resistor will mount vertically, the same as the existing. The new capacitor will have to be mounted to the other side of the circuit board due to its size. You will have to install a small foam block under the crossover to support the weight of the new parts, due to the thin solder tabs on the new binding post cups.
Replace the SL2500s with RDO-198-1 Tweeters.
Install Dynamat on the woofer basket frame, and install a 4" X 4" section of Blackhole5 directly behind the woofer.
Glue the Magnet assemblies with Loctite Power Grab, Clear Acrylic Adhesive. Re-seal if needed, the Cabinets internally, with the same Loctite Power Grab.
Install Hurricane Nuts or Larry's Rings with machine screws for the woofers and tweeters. I used Black Oxide Coated, SS, Phillips Head Machine screws on mine originally, but have switched to Torx head machine screws.
The cabinets are relatively small, made from 3/4 particle board, and are quite solid. No internal bracing should be needed.

babyjames

Thanks, westmassguy. I really like these speaks! Put the Klipsch Kg1's I was running previously to shame.

No bracing, huh? There's a ton of resonance in the rear baffle, especially at volume. To my ears the bass is a little muddy. I was thinking the bracing might help to tighten that up a bit?

Never made any speaker modifications before, honestly. Had JBL L80T's back in the day. Love the late eighties box sound! Call me a dinosaur (or whatever else you like, my skin is pretty thick; goes for my skull, too!).

Jay

westmassguy

It won't hurt to put a brace in, other than reducing the internal volume. Mine do not exhibit that. Re-sealing the back panel internally may help, and let's not forget, the crossover is sticking out in mid air on that model. It could be picking up vibrations and transferring them to the back wall. Muddy bass could be due to the woofers basket frame resonating, and not being torqued down. Those would be eliminated by the upgrades.

babyjames

Phase one complete! Rather than soldering the crossover board directly to the terminal cup, I relocated it to the floor of the cabinet, using some 14ga silver-plated wire betwixt the two; resting snugly on a damping foam mattress to which it is cable-tied Installed hurricane nuts - considerably less expensive than SS tee nuts, but also considerably more finicky and harder to install. 1/2" damping foam material was more economical, so I went that route, covering a slightly larger area on the rear baffle. Put dynamat on the backs of the magnets of both drivers and on the woofer basket. Cut a piece of 1" dowel to fit quite snugly between the front and rear baffles, situated dead center, longitudinally, and between the drivers. Firmly secured with Gorilla Glue.

Sound pretty good! Performed, roughly, the same upgrades to my Klipsch KG-1's and noticed a more dramatic difference. On the KG-1's I did, however, completely rewire them using the same 14ga wire cup-to-crossover, and 18ga silver plated wire from crossover to drivers.

The 4.6's are "easier" to listen to - not nearly as bright as the Klipsch - but don't image NEARLY as well.

I'll rewire the Polks and replace the tweeters and caps/resistors as $$'s permit.

Many thanks, again, Westmassguy. Still not super happy with the bass response. I honestly think 30hz may be a bit over ambitious for the cabinet size, but I'll keep listening for a while before passing judgment....

Jay