SDA-1C Refurbish Plan

Sea

I recently acquired a pair of 1C's in OK shape. All of the side panels are coming loose and have previously been glued back on with what looks like linoleum cement, a real mess. One of the MW6510 drivers would nit play at all. I did not listen to them long but the sound was muddled and very rough. The cabinets were noticeably resonant.

This is my initial plan along with a few questions.
1. Clean up the cabinets, removing all of the cement. Underneath all of this gunk is black vinyl. I guess all 1C's sort of started as Studio models and some got upgraded with fabric side panels and wood tops. I also plan to use some sort of caulk to be sure the cabinet is airtight I think I have read of a lock tight product.
2. I plan to either recover the existing panels or perhaps start with fresh MDF. I am planning to make the panels removable.
3. Recover the grills
4. Dynamat the drivers.
5. Attach drivers with hurricane nuts
6. Replace the bad driver (already ordered)
7. Replace tweeters with 1094's (Already ordered)
8. Install spikes

This brings me to my first question. I have read where some line the entire cabinet with sound barrier and I have also read about the black hole 5. I am a little confused. If I understand correctly it would not be possible to do both. Which is more beneficial?

I think my plan is to get this far and then invest some time listening before I proceed to upgrade the crossover. If all goes well, I plan to evict the RTi12's from the living room.

Comments and suggestions are welcomed.

Conradicles

Here is a picture of a pair I did some years ago: The Black Beauty

F1nut

Do NOT cover the interior with sound barrier.

I suggest you do the tweeters and crossovers first.

westmassguy

This^^^^^^^^^^
The product I use to re-seal any suspect internal joints is Loctite Power Grab, Clear Acrylic Adhesive. It comes in 6oz tubes. Lay a bead, then smooth it out with your finger tip. Dries to a clear, matte finish. You can also use it to glue the magnet assemblies on the woofers instead of JB Weld or other types of epoxy. Use 3" wide strips of Blackhole5 behind the woofers only, and under the Dacron Batting. The BH5 and the Dacron should extend no lower than the bottom of the lower woofer opening. The bottom of the cabinet should be free of any damping material.

Sea

Thank you for the suggestions.

westmassguy

You're welcome. I can also give you tips for installing the Hurricane Nuts, when you're ready. BTW, do not use any type of silicone sealant, or any acrylic sealant containing silicone.

drumminman

westmassguy wrote: »

This^^^^^^^^^^
The product I use to re-seal any suspect internal joints is Loctite Power Grab, Clear Acrylic Adhesive. It comes in 6oz tubes. Lay a bead, then smooth it out with your finger tip. Dries to a clear, matte finish. You can also use it to glue the magnet assemblies on the woofers instead of JB Weld or other types of epoxy. Use 3" wide strips of Blackhole5 behind the woofers only, and under the Dacron Batting. The BH5 and the Dacron should extend no lower than the bottom of the lower woofer opening. The bottom of the cabinet should be free of any damping material.

This is it in a nutshell - good advice.

Sea

Thank you westmassguy. I would love some tips on the hurricane nuts. I hope to get to that point sometime over the weekend.

westmassguy

Sea wrote: »

Thank you westmassguy. I would love some tips on the hurricane nuts. I hope to get to that point sometime over the weekend.

The Hurricane Nuts can be found here: http://www.parts-express.com/8-32-hurricane-nuts-50-pcs--081-1080
I've used #8-32 Phillips, Pan Head, Black Oxide, Stainless Steel, 1 1/4" Machine Screws. They're a dead ringer for the original Polk sheet Metal Screws. I've now switched to Torx, Pan Had Cap Screws. I prefer them since there's little chance of slippage when tightening them. You can also use Flat Head Screws for the Tweeters. The Pan Heads don't quite fit the recess in the plastic bezel, while the flat heads will mount flush. Regarding the Hurricane Nut installation, you'll need a variable speed drill, preferably with a level bubble on the back end. The hole size is 13/64" for the 8-32 size nuts. Don't drill out the holes with that size immediately. I use three drill sizes to enlarge the hole gradually. Start with 1/8", then 5/32", finishing with the 13/64". This prevents splitting the particle board, or worse, blowing out a chunk of material on the back side. Lay the cabinet on its back, on a level surface. The 1/8" starter bit will follow the original screw hole. Use low speed, and don't apply any pressure to the drill, let the weight of the drill make the hole, and check the level bubble if your drill has one. Do all the holes with the 1/8", then move up to the 5/32" and so on. Next, I use a 3/4" or 1" wood chisel to clear any burrs off the back side of the holes. You may find excess hot glue where the holes are drilled. this can be removed with a heat gun, or hair dryer set to high. The hot glue must be softened with the heat, then use a chisel or putty knife to clear the areas where the Hurricane nuts will be installed. To set the Hurricane Nuts, I use a small 1/2" diameter washer, and a couple of sacrificial screws. Put the washer under the head of the screw, hold the Hurricane Nut to the back of the hole, manually start threading the screw, and finish with the drill with a Phillips or Torx bit in it. Use low speed, and you'll know when the Hurricane Nut is seated by the sound of your drill. The washer helps prevent the screw head from sinking too far into the particle board as its pulling the Hurricane nut up into the hole. The H Nuts should be installed on the Tweeters, Woofers, and Passive Radiators. You do not need to install them on the Binding Post Cup. The Cup only receives air pressure fluctuations, and doesn't produce any mechanical stress like the other components do. If you screw up one of the Hurricane nuts, and it spins or doesn't fit tightly, remove the H Nut, take a Q-Tip dipped in hot water, and thoroughly wet the inside of the hole you drilled, and the back side. Let it sit overnight. This will swell and expand the particle board, and it should grip the H Nut without using glue. Some prefer to cut a flat on the shoulder of the H Nut, so it doesn't overlap, and protrude into the opening. That's strictly for aesthetics. I've never had to do it, there's plenty of room between the basket frame of the woofers and PRs, and the H Nuts. Lastly, when installing the drivers, you can use the drill to thread the screws most of the way, but final torqueing should be done be hand. They should be tight, but not overly torqued. Wait a day or two, and retighten. This allows the gaskets to compress fully.

tophatjohnny

That or put some Polk love into them and find yourself some "Larry Rings" they are waaay too cool!!

Sea

I am pretty sure I read somewhere that 10-32's were used and this is what I have ordered. I don't mind so much the added expense but I hate to wait. I think the 10-32's will be here today. Oh well, I do want to do it right, not necessarily quick.

I was under the impression that Larry's Rings were no longer available??

westmassguy

tophatjohnny wrote: »

That or put some Polk love into them and find yourself some "Larry Rings" they are waaay too cool!!

John, pretty sure he's stopped making them

westmassguy

Sea wrote: »

I am pretty sure I read somewhere that 10-32's were used and this is what I have ordered. I don't mind so much the added expense but I hate to wait. I think the 10-32's will be here today. Oh well, I do want to do it right, not necessarily quick.

I was under the impression that Larry's Rings were no longer available??

#10-32 are larger than what you need, and the drill sizes are different than I listed

Sea

I will order the 8-32's

nspindel

I've got plenty of spare BH5 after the Monitor 10 rebuild I just did, I could sell you just the amount you need so you don't need to buy a full sheet. PM me if you're interested.

I don't see you mentioning anything about any crossover upgrades?

Sea

Great. Sent you a PM about the BH5. I plan to do the crossovers just have not got that far yet. It is confusing with all of the options for capacitors. I am trying to sort all that out in my addled mind.

nspindel

For the caps, if you've got the funds go with Sonicap or talk to Trey about Clarity. If you want to save some money, substitute Dayton's for the shunt caps. You should also look at replacing the boards, the inductors, and the resistors. You've got a great set of speakers there, I used to own 1C's. I never did any cosmetic work, but sold them to a friend who turned them into a masterpiece:

http://www.polkaudio.com/forums/showthread.php?156102-SDA-1C-dovetailed-walnut-project

nspindel

Duplicate post

drumminman

Hurricane Nuts alternate method - get a drill bit the size of the shaft of the H-nut, but not as big as the little wings that protrude from the shaft. The wings are what keep it from turning as you tighten the screws. Use the existing hole as a guide and drill straight through that. Place the H-nut inside the cabinet and your screw outside and begin threading by hand.

Be sure the H-nut is aligned. Once you meet a little resistance while turning the screw begin slowly torqueing - you'll feel the H-nut pull into place.

I've done both my 12C's and 2.3TL's using this method without any issues.

Sea

Really not much progress today. I have pretty much cleaned up the cabinets and removed all of the glue. I have taken the tops and bottoms off and arranged today to have new ones made from solid walnut. I plan to reattach with bolts instead of glue.

Still waiting for tweeters and the one replacement driver from Polk. I plan to install the tweeters and listen to them as is for a few hours so I will have a point of reference to compare to as the mods are completed.

I am still undecided how to proceed with the crossovers. So many choices and such a big range in cost.

Schurkey

Sea wrote: »

I am still undecided how to proceed with the crossovers. So many choices and such a big range in cost.

You pretty much cannot make a "bad" choice; just about any of your options are better than continuing to use the original electrolytic caps.

F1nut

I have taken the tops and bottoms off and arranged today to have new ones made from solid walnut.

You guys going to solid wood end caps are going to be sorry one day when they start to crack and/or warp. Wood moves with changes in humidity and when it can't move bad juju happens. There's a really good reason why Polk used veneer. Besides that extremely important point, end grain says amateur.

Sea

ouch! i had not considered the end grain issue, but I really respect your opinion. One reason I was considering solid is that I have had a hard time finding a small quantity of veneer. I am not committed to solid yet so this will make me ponder further. Thanks.

westmassguy

Sea wrote: »

ouch! i had not considered the end grain issue, but I really respect your opinion. One reason I was considering solid is that I have had a hard time finding a small quantity of veneer. I am not committed to solid yet so this will make me ponder further. Thanks.

http://www.ovisonline.com/Wood-Veneer-Walnut-Quartered-2x8-PSA-Backed-P1538C69.aspx
Beautiful stuff, and very easy to work with.

Sea

F1nut wrote: »

You guys going to solid wood end caps are going to be sorry one day when they start to crack...

If I go the new veneer route can i just apply new right on top of the old veneer?

westmassguy

Sea wrote: »

If I go the new veneer route can i just apply new right on top of the old veneer?

Yes, with a few caveats. The existing veneer should be thoroughly checked to make sure it's not lifting, and is perfectly smooth. All dirt and wax buildup must be removed. All voids filled. If you go with the PSA Backed veneer, the old veneer should be sealed with lacquer first, so the PSA can adhere to it.

Sea

Thanks. We have two local sources of veneer. I think I will check them out. Woodworkers Supply and The Hardwood Store of North Carolina.

westmassguy

You're lucky, we have nothing around these parts. We have some very good lumber yards, but veneer must be ordered.

Faustin

You can also check online with www.veneersupplies.com. They have a great selection and after checking other sources, some of the best prices. I am just finishing up re veneering my RTA 12c's and will be posting pictures in the next few days.

Sea

Great Thanks for the tip.

F1nut

Sea wrote: »

If I go the new veneer route can i just apply new right on top of the old veneer?

Yes and no. When layering veneer it is best to do each layer perpendicular, which is this case wouldn't look too good. Also, adding another layer will increase the overall dimensions of the end cap, which height wise wouldn't be a problem, but width wise could cause overhang depending on the thickness of the veneer used.