My SDA 2B Studios rebuild

ROHfan

As noted in another thread, I'm going to document my SDA rebuild journey here with some pics. Perhaps this will be helpful to someone else who wants to take on the task.

I have to thank Harry (polrbehr) for his quick responses to my frantic, and often panicked, emails and texts. It's great to have a guy like that in your corner to be able to bounce ideas off. Thanks also to Trey from Vr3 Mods, Jesse, westmassguy and voltz for their input--whether it was for this rebuild or rebuilds that they've commented on in the past. And of course thanks to anyone who's shared their SDA journeys. Your stories were the inspiration for this rebuild.

Recently, I bought a pair of black SDA 2B Studios for $100 on CL. One of the SDA drivers was frozen, the IC cable was missing, and the cabinets had some mild damage to the corners and vinyl. All fixable stuff. The guy I bought them from goes around bidding on vacant storage units and he found these speakers there. Lucky me! I called Polk and swiftly ordered two RDO198 tweets for the TL mod, one new MW6511 SDA driver to replace the frozen one, and one new, hand-built IC cable from Hank in the Polk warehouse. I got the speaker/tweets in a couple of days but I'm still waiting for the IC cable. Perhaps one day Hank will work a little quicker.

I removed all the drivers and passive radiators and the inside was real clean, which was a bit of a relief. The next thing I did was take out the crossovers/electronics and get in touch with Trey from Vr3 mods to discuss options. Aside from being a skilled craftsman, Trey is also a very patient man, as is evidenced by him not putting a hit out on me for the roughly 200 emails I sent him over the course of two days asking tons of stupid, redundant questions. And he turned the mods/upgrades around very quickly. This was a huge relief, as rebuilding these speakers is obviously the most pressing matter in the entire nation, today.

Here's a crappy pic of the cabinets without the guts, and with a pair of hitchhiking Dynamatted Passive Radiators:


Here's another crappy pic, but this time it's the stereo and SDA drivers, JB welded and Dynamatted, as well. SDAs are on bottom, and the new SDA driver from Polk is bottom right. Notice the slight difference in the new speaker's basket and magnet? Of course you don't. I told you it's a crappy picture:


The next post I'll have some pics of the modified/upgraded crossover and binding posts. I will try to make the next pics not as crappy.

polrbehr

I know you've made some good progress with this (and no thanks necessary, I will be relying on your journey when I finally get mine fully modded and veneered), got any fresh pics or good stories to post?

ROHfan

polrbehr wrote: »

got any fresh pics or good stories to post?

As a matter of fact, I do!

Adding Armaflex pipe insulation to the drivers was a piece of cake. And because the stuff is so soft they were able to bend with the radius of the driver without wrinkling and bunching up. Same goes for where they seamed together. Here's a couple of pics of the drivers getting new gasket treatments:





The stand off brackets holding the PCBs to the inductor were very loose so I hit them with some hot glue before securing them to the inside of the cabinet. Here's a pic of the one of the crossovers:



Cabinets awaiting their new guts (you can see the edges of the Hurricane nuts poking out through the driver holes):



I had planed to use Larry's rings but was never able to get in touch with him. If I do eventually get them I'll swap out the H-nuts.

There was an issue with the new crossover pigtails as the disconnects that were used wouldn't fit the driver terminals. I didn't want to "fudge" anything so I grabbed some insulated disconnects that I had lying around. They were good-ole 1/4" standard disconnects that fit perfectly. I plan to replace these with gold plated ones in the future. Does anyone have a reliable source for these?

After putting everything back together and giving them a test drive I noticed that the left speaker's 6503 was bottoming out. And it was in the same cabinet that had contained the frozen 6511 so I guess the cabinet must have been banged around a bit. I wound up ordering a new 6503 from Polk and got it three days later.

Once everything was assembled, again, they sounded marvelous. But there was a buzzing. D'oh! I remember one of the pigtails was really close to the partition brace inside the cabinet so I'll have to get some more fluffy stuff so I can fix the issue.

The next steps won't be done until it gets a little warmer. I plan on adding veneer and spikes. I'm using a makeshift interconnect cable right now until I get the new one from Polk, but I can tell you these are definitely going to be replacing my Martin Logan Electromotions once everything's done. You may see them in the For Sale section here soon.

Malbec

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I plan to replace these with gold plated ones in the future. Does anyone have a reliable source for these?

[/quote]

http://www.partsconnexion.com/connectors_disconnect_furutech.html

Jasper67

A little help with the Hurricane Nut install. I purchased the HN's for my Studio 2b's from Parts Express and I received them yesterday. From a quick visual inspection, it appears that the flange is too big to sit inside the channel on the cabinet. Is there a modification that needs to be made to the HN's or did I buy the wrong parts? Below is what I purchased.


https://parts-express.com/parts-express-8-32-hurricane-nuts-50-pcs--081-1080

TennMan

The H-nuts should work without modification but you could do as I did and remove part of the disc so it won't be seen through the holes.

Saw the dotted line OR clamp the edge of the disc marked with the red X in a vise, then screw in a long screw and use it as a lever to work the H-nut up and down until the X edge breaks off. Hit a lick with a file to smooth the edge and your ready to install.

Don't drive the H-nuts in. Pull them in with a screw to avoid damage to the wood.

Jasper67

So I did a little research and I believe I was looking at this backwards. It appears that the hurricane nuts reside inside the cabinet not on the surface. Correct? Do I need to drill out the screw doles in advance to accommodate the larger diameter of the HN? One site I looked at mentioned putting epoxy on the nut and then pulling it into the cabinet with the screw from the surface side side. Is this necessary?

TennMan

You have to carefully drill the existing holes out to the proper size so the h-nut has to be forced into the hole with just the right amount of pressure to cause the flutes to bite into the wood. The flange will be inside the cabinet.

Westmassguy has good instructions for how to do this, including the proper drill bits to use. I'm sure he will be along to post them for you.

stogie

ROHfan, here's another link for gold plated disconnects:
https://www.madisoundspeakerstore.com/quick-connects/

cascius

Thanks for sharing your experience. I'm placing a bunch of orders today to fully upgrade my sda-2Bs and it's definitely exciting.

By the way, i've already added spikes to mine. What I did was remove the old speaker base, drill 4 holes 1 inch away from the corners and installed the spikes. I decided to do it 1 inch away to avoid drilling into the sides' MDF. I made the mistake (maybe) of drilling all the way through the MDF though, so I ended up using some loctite inside the cabinet to make sure there wasn't any air leak. A quick pressure test shows that I fixed any potential issue, it takes 4 seconds for the MWs to go back to their starting position.

The speakers are now much better connected to the floor and feel rock solid.

Have fun with all the upgrades and keep sharing your experience,

Olivier

Jasper67

Oliver, I am installing spikes this weekend and I'm wondering why you removed the base? This isn't something I even considered. How do you perform the pressure test if I follow your lead?

Anybody else have an opinion on this mod?

I have the studio 2B's

cascius

Hi Jasper, i decided to remove the base for a few reasons:
- the bases were extremely damaged
- in order to add spikes to the bases, i would have had to reenforce them
- i prefer the look without the base ;-)

Here's a picture:


For testing the pressure:
- gently push the PR in; the woofers should come out
- observe the woofers, they should go back to their initial position in 2 to 5 seconds. 2to3 being okay, 4+ great.

Please correct me if i'm wrong.

Olivier

Jasper67

Very nice Oliver! Love the finish on the 2B's vs. the studio version but "ya got what ya got" I'll have to give this one some thought. Was it hard to remove the base?

cascius

Not at all: four screws, and then I put some wood putty to fil them. That was it. ;-)

Regarding the finish, mine were in such bad shape that i just filled all the holes/corners, sanded, and covered with some cheap Vynil from Amazon.

The result is actually pretty good.

Jasper67

so were yours before the mod 2b's or studio 2b's?

cascius

They were/are SDA-2As. Soon to be 2A-TL

VR3

Looking good

F1nut

Jasper67 wrote: »

So I did a little research and I believe I was looking at this backwards. It appears that the hurricane nuts reside inside the cabinet not on the surface. Correct? Do I need to drill out the screw doles in advance to accommodate the larger diameter of the HN? One site I looked at mentioned putting epoxy on the nut and then pulling it into the cabinet with the screw from the surface side side. Is this necessary?

Use a 7/32" drill bit, a new one. Dab some 5 minute epoxy on the H nut flange. Hold the H nut in place on the back side of the hole while slowly threading the screw by hand to start with. Once you are sure the screw is not cross-threaded use a screwdriver or allen driver depending on what type screw you are using to finish the install. It's best to use a washer on the screw to stop the screw from going in too far when it hits the driver mounting flange.

As for spikes, remove the base on your 2B Studio's filling the 4 holes after. I recommend using 2" tall spikes, which will add one inch in height bringing the tweeter closer to ear level. If your spikes are less than 2" tall, return them and get the proper ones, it makes a difference.

When drilling the holes for the spike inserts, if you don't have a drill stop, put the insert next to the bit, wrap a piece of tape around the drill bit where the top of the insert is and you now know when to stop drilling.

Faustin

Here are detailed instructions to install the hurricane nuts per westmassguy - (Dave).

Hurricane Nuts and Machine Screws: Replace all the existing black sheetmatal screws with this new attachment method to improve the overall sound by reducing resonances/vibrations, and air-tightness of the cabinets. Hurricane Nuts can be found here: http://www.parts-express.com/pe/showdetl.cfm?partnumber=081-1080 , Black Oxide Coated Machine Screws can be found here: http://www.ebay.com/itm/36-ea-8-32-x-1-Phillips-Pan-Head-Screws-Black-Oxide-/230911004314?pt=LH_DefaultDomain_0&hash=item35c35e4e9a . This seller will make up special quantities for you. I buy from him exclusively for these machine screws, as they are dead ringers for the original sheet metal screws Polk used.
The new hole for the #8-32 Hurricane Nut is 13/64". Do not deviate from this specific size drill bit. To make the holes, I use three different size bits, to increase the size of the hole gradually. If you try to drill out the particle board with the 13/64" bit, you risk splitting the particle board, or blowing out a chunk of it on the back side. Instead, start with a 1/8" bit. Place the cabinet on it's back on a level surface. Drill out each hole at low speed with variable speed drill , do not put pressure on the drill, let the weight of the drill do the work. The 1/8" bit will follow the original screw hole, and your holes should end up relatively straight and plumb. Next, switch to a 5/32 bit, drill out each hole, then finally switch to the 13/64" bit, and repeat. You should end up with clean, plumb holes, with little or no splitting or damaged particle board. Installing the Hurricane Nuts is quite easy. You'll need one or two sacrificial machine screws, and a small washer to fit under the head of the screw. The washer prevents the head of the screw from sinking into the particle board. You can manually screw in each Hurricane Nut, or use a variable speed drill with a phillips bit. Hold the Hurricane nut under the hole with the fluted part pressed against the hole. Insert the machine screw and washer into the top of the hole, and manually start the thread. You can use a screw driver or drill to tighten the nut. Once the screw threads down and hits the face of the particle board, the threads draw the Hurricane nut up into the hole. Once the back flange of the Hurricane nut is flush with the particle boad, your done. Remove the screw and washer, and move on to the next.
Note, you do not need to install hurricane nuts on the crossover mounting holes, only the front drivers, tweeters, and PRs.

pitdogg2

stogie wrote: »

ROHfan, here's another link for gold plated disconnects:
https://www.madisoundspeakerstore.com/quick-connects/

advanced auto and autozone carry them also.

Jasper67

Any recommendations on weather stripping for the gaskets? I have read a few different recommendations from Mortite rope caulk to standard weather stripping.

stogie

Most folks here have gone from Morite to Armacell Insulation Tape:
http://www.homedepot.com/p/Armacell-2-in-x-30-ft-R-1-Foam-Insulation-Tape-TAP18230/100539553

F1nut

Jasper67 wrote: »

Any recommendations on weather stripping for the gaskets? I have read a few different recommendations from Mortite rope caulk to standard weather stripping.

If your original gaskets are not damaged there is no reason to change them.

ROHfan

Thanks for the comments, and the suggestions on the disconnects. I think I'm actually going to solder the wires to the terminals, instead.