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  1. #1

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    Default SDA 2B TL upgrade (Studios)

    I recently made various upgrades to my Studio 2B's. Since there have been a few questions recently about doing similar mods I thought I'd post some notes about my process. Most of this information has been covered elsewhere, so hopefully this isn't just adding noise, and I'll be linking to other threads where some steps are given better treatment than I could manage. As much as anything else, I'm doing this to consolidate links to the best posts on how to perform some of these mods.

    Unfortunately, I'm doing this after the fact, and I'm not especially good about taking pictures as I work so it'll be light in that regard. But again, most of the heavy lifting has been done by others, and I'm just aggregating info. Maybe we need to start a Polk wiki somewhere.

    Also, this is going to be limited by my experience, which wasn't necessarily typical, and I've definitely got a lot to learn. I hope folks will jump in and say what could have been done better. I'll try to leave enough space in between posts so that can happen.

    Here's what I think will get covered:

    1) Deciding what upgrades to make
    2) Procurement
    3) The 2B TL crossover upgrade using Gimpod's custom PCBs
    4) J-B Weld on the MW magnets
    5) Dynamat on the MWs and PRs
    6) New mounting hardware for the MWs and PRs (Rings)
    7) New binding posts (and one for the IC)
    8) Spikes

  2. #2

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    Default Decisions, decisions

    Generally, I'd rather listen to my speakers than mess with them, so I try to get all my upgrades batched up and do them at a shot. I gave consideration to just about everything Polkies do to their speakers. I ruled out one mod right away.

    Mortite: a solution in search of an audio application. For anyone who doesn't know, Mortite is a press-in weatherstripping product that exists somewhere on the continuum between caulk and string cheese. In addition to sealing the exterior windows in your home, you can use it to make sure your speaker cabinets are airtight. I guess I've been lucky, but I've never had a problem with this. I've had several pairs of Polk speakers, and none of them have ever failed the PR push test.

    In the push test, you gently push in (hence the name) on the PR and watch the MW drivers flex out on their surrounds. They shouldn't recede to a neutral position immediately; it should take several seconds. On my speakers, they will take anywhere from 5 seconds to I-get-tired-and-let-go-of-the-PR. If your MWs recede faster than that, consider the Mortite as an alternative to buying gasketing tape from Parts Express. Otherwise, if you can keep the stock gaskets intact when removing your MWs/PRs/tweeters, you probably don't need it. The best argument against is F1nut says it would be a better use of your time to just take a nap.

    Since I didn't use the Mortite, I won't be discussing it later. Prevailing wisdom is if you use it with the stock wood screws as mounting hardware, flatten a cord of it out a bit first behind the lip of the MW/PR (where the gasket goes) and tighten the screws slowly and over multiple sessions. Allow the mortite to relax in between tightenings or you will strip the screws and end up with a less than optimal seal.

    Here is a poll and discussion of whether it is worthwhile. And here is a recently discovered alternative. Obviously, sealing your speakers is a continuously evolving art so you might want to reuse the stock gaskets and wait til the heavy hitters learn from experience which performance enhancing substances are safe.

    J-B Weld: When you're conducting your push test, if any of your MWs fails to move out it's probably because the magnet on that MW has shifted. The magnets are held to the MW with glue, and as the glue ages it weakens enough that letting the speaker within 10 feet of anyone wearing brown shorts and socks is likely to have you talking to Polk Customer Service about replacements. If the speakers are likely to be subjected to any jarring impact, you might want to use J-B Weld to permanently cement the magnets in place. Plenty of folks will tell you this is unnecessary otherwise, but it's cheap insurance. I decided to go ahead and do this one, especially since MW6511's are nigh impossible to find on the used market.

    Dynamat: While we're on the topic of the MWs, if you've got them out you might as well consider using some Dynamat Extreme to make sure the sound coming out of them (and the PRs) is only the sound described by the source material. The baskets have a bit of a "ring" to them. Hold them by the magnet and give them a flick like your kid brother's ear. You can kill that bell-ring effect by using Dynamat, which is a specially engineered sound/vibration deadener made for automotive applications, but works great for this too. This one was a no-brainer. Not expensive or difficult and no downside risk.

    Rings: Another synergistic enhancement to the MWs and PRs is to improve their mounting hardware. The stock wood screws aren't necessarily bad for their intended purpose, but if you mess with them enough, you will strip the holes in the particleboard to the point where they are more push-pin than screw. The preferred solution here is to use the mounting rings engineered by fellow forum member, machine-shop guru, and fabricator extraordinaire ToolForLifeFan. Sadly, they are only intermittently available, but there are alternatives. I have used the rings before and fully intended to use them on this upgrade but hit a snag. I'll have more to say later.

    Binding Posts: I used to wonder whether expensive binding posts were beneficial beyond being just pretty, but recent experience has taught me that they do make a noticable difference. And they are a lot more pretty. Next to Vandersteen (seriously, screw terminals!?), Polk wins the prize for ugliest connectors on an otherwise good speaker. This was another easy decision, and I decided to upgrade the IC connection with a new binding post too so I could use something better than the stock cable (not that it's bad).

    Spikes: The 2Bs are a shorter speaker than the other SDAs, and I think elevating them a couple of inches is beneficial. Adding spikes will accomplish that and give a little bit of isolation over the stock plastic feet. I went for convenience over quality here, but I did add spikes.

    The TL Mod: Finally, the most obvious mod is the upgrade to the crossovers and tweeters. The extra money you'll spend on the TL mod over just rebuilding the stock XOs and replacing the SL2000's with the RD0-194 tweeters is insignificant next to the overall upgrade cost and the time you'll spend. Personally, I think if you have 2Bs and you're not going to TL them you might as well just give them to the neighbor lady so she can use them as a plant stand/scratching post.

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