SDA 2B's where to start?

littlewoodboats

As I put up in my first thread I am the proud pappa of a nice set of SDA 2b's.

I am not having the best of luck with the search function so have a couple of newbie questions I know have been covered in the past. Sorry about that.

The leak test yielded less than stellar results. The mids came up and fell right back to level. If I rushed the count I might have gotten to one. I had planned to use Moretite, then I ran across the gasket thread. After making an inquiry I was told there were enough left to do my cabinets so I ordered the set.

I have Dynamat for the driver baskets. I have read something about moving magnets and J B weld? I found references but nothing specific on how or why this is to be done.

Are the cabinets supposed to have feet?

I think I read something about the insulation inside the cabinets and was hoping someone could guide me in the right direction.

I am not planning to update the tweeters or crossovers at this point for two basic reasons. The first is I have not made any final decisions on how I plan to drive them. The biggest reason is my new house is not ready so I have not heard them in the room where they will live. I currently power them with 15 watts Class A and have no complaints with how they sound. No loud volumes obviously.

Thank you for any and all input.

Steve

brgman

http://www.polkaudio.com/forums/showthread.php?128224-How-to-do-the-JB-weld-mod-and-not-make-a-mess&highlight=weld

here's a good start

littlewoodboats

I think I have it now. Thanks brgman. It is not necessary to disassemble the driver just use the epoxy to glue it all together as a preventative?

inspiredsports

There's no harm in running a couple of beads of JB Weld around the steel and magnet margins of the magnet assemblies(DO NOT dissasemble as that will basically destroy the MW), but I will share this: I have a couple dozen mid-80's MW drivers in play that I use almost daily that are not JB-Welded. Bonding the margins is critical for shipping, but I personally have never had a magnet shift during normal use.

Dynamat is a rewarding bang-for-the-buck tweak.

Sealing the cabinets, however, is critical for proper bass response. The cabinet itself (joints) passives radiators, MW drivers, tweeters and the speaker cable connection assembly on back need to be sealed so you get the approximate 3 second air bleed time.

You didn't name your class A amp, but I will say a fully modified 2B may be the SINGLE BEST CHOICE you can make if your efforts trend toward what can be accomplished with great source components and amps.


Welcome to Club Polk!

F1nut

The leak test yielded less than stellar results. The mids came up and fell right back to level. If I rushed the count I might have gotten to one.

Did you push and hold in the PR or did you release the PR right away?

littlewoodboats

Right now I am using an early 70's vintage Yamaha CA-1000 with the selector welded to A. If one switched back and forth between the selections when the amp was powered it would weld the switch. Works great other than that so for $20.00 I feel pretty good about the whole deal. My CR-840 went up in smoke (RIP old friend) so I put this back in service. I am having a CR-2020 restored and will use that while the 1000 goes in for overhaul.

I had a plan in mind when I bought these but now find myself lusting after a set of tube amps (not sure how to deal with the common ground necessity) to run with my Velleman passive preamp.

They do sound sweet and I know sealing the cabinets and the dynamat will make a big difference.

Do the cabinets use any dampening materials on the inside? If so is there anything that requires special attention?

Thanks for the welcome. I went into the Navy shortly after Polk hit the town where I was living so never had the space or money for gear like this.

Fun times.

falconcry72

littlewoodboats wrote: »

...I am not planning to update the tweeters or crossovers at this point for two basic reasons. The first is I have not made any final decisions on how I plan to drive them. The biggest reason is my new house is not ready so I have not heard them in the room where they will live....

Regardless of how you end up driving them and what they sound like in the room, replacing the tweets will be a big improvement.

The cool thing about that particular mod is that it's super easy, and if you don't like how the new tweets sound (which is a very low probability), you can sell them for 80-90% of what you paid for them.


Congrats on the sweet speakers! I have a pair and love'em!:biggrin:

littlewoodboats

Okay, you got me. I just ordered a pair of the RD0194's :cheesygrin:

The guy at Polk told me they would ship tomorrow from California.

TennMan

littlewoodboats wrote: »

Okay, you got me. I just ordered a pair of the RD0194's :cheesygrin:

The guy at Polk told me they would ship tomorrow from California.

Good move. You will like them.

sda2mike

they'll sound great out of the box...the burn-in is approx 100 hrs, they'll sound even better then

evhudsons

That feeling during the break in period is addicting. It's a great first rush and audio high to hear such amazing improvement that just gets better and better. Welcome to the club, you'll find more addiction information here, but not any sympathy for your addiction.

Those are great speakers and even better when you put the new tweeters in.

deronb1

Welcome! and congrats. Where are you from?

littlewoodboats

I am in East Texas not far from Lufkin.

brgman

Near the wonderful Lufkin gearbox manufacturing facility eh?

littlewoodboats

brgman wrote: »

Near the wonderful Lufkin gearbox manufacturing facility eh?

Yes indeed. Most people who live here do not know what they do other than the heavy trailers. They have a pumping rig decorated like Rudolph that they haul to the mall for the Santa village every year. Funny looking thing but I have seen it for so long it would not be Christmas without it around.

F1nut

You haven't answered my question in post #5.

frickingruvin

I'm on the same quest. I replaced one mid and the tweets with 194s. I have also sealed the tweets and mids with mortite and treated them with dynamt. I haven't yet treated the pr's. I am planning on recapping both and I will treat the passives at that time. I already hear an improvement...They are a great speaker....

littlewoodboats

F1nut wrote: »

You haven't answered my question in post #5.

Sorry about that. I did hold them down. The mids came up as the PR went down but went right back down once I hit bottom with the PR.

littlewoodboats

Are the RD0-194's a direct replacement or is there some fitting required?

gwg_97

littlewoodboats wrote: »

Are the RD0-194's a direct replacement or is there some fitting required?

They are an easy direct replacement.

F1nut

littlewoodboats wrote: »

Sorry about that. I did hold them down. The mids came up as the PR went down but went right back down once I hit bottom with the PR.

Ok, just checking as some folks do the test wrong. Other than changing the gaskets, be sure to check the cabinets for air leaks.

frickingruvin wrote:

I have also sealed the tweets and mids with mortite

Use Armacell instead. Mortite belongs on window frames, etc., not speakers.

F1nut

Are the cabinets supposed to have feet?

I meant to answer this in my last post.....

The 2B's (regular or studio) came with plastic glides, not screw in feet. The benefits from installing good spikes is not subtle.

sda2mike

F1nut wrote: »

The benefits from installing good spikes is not subtle.

+1 on that

littlewoodboats

gwg_97 wrote: »

They are an easy direct replacement.

Cool. We are professional wood boat builders so a cabinet modification is not an issue but the time to deal with it would cut into profits. (my accountant tells me there aren't any right now :frown: )

Ok, just checking as some folks do the test wrong. Other than changing the gaskets, be sure to check the cabinets for air leaks.

When I first decided I wanted to go this route I started lurking to find the booby traps waiting for an uninformed buyer. When you say check the cabinets for leaks do you mean where the wood joins? How does one test for this or is it something to just treat? I have some spray stuff we use for repairs that is for sealing leaks in wood joints.

My cabinets are missing the feet. For the time being I have some small furniture feet I can put on them and do the spikes once I am moved. I would expect to hear a difference. I am not sure if this applies to the Polks but I have always been told that you want to have the tweeter at ear level when possible.

Thanks for the information

TennMan

F1nut wrote: »

I meant to answer this in my last post.....

The 2B's (regular or studio) came with plastic glides, not screw in feet. The benefits from installing good spikes is not subtle.

sda2mike wrote: »

+1 on that

I've been thinking about putting spikes on the stands for my 10Bs. I'm not sure if there would be any benefit from doing it with them sitting on hardwood with discs under the spikes to protect the floors.

I can see the benefit of having spikes on carpeted floors but I can't see how spikes sitting on discs would be better than the plastic glides like I now have.

I've read lots of spike reviews on websites that sell them. Most of the reviews are about ease of installation, not about how well they work. Do you guys feel that I would get better sound with spikes versus glides if the spikes must be used with discs? Your thoughts about spikes on hardwood would be appreciated.

inspiredsports

littlewoodboats wrote: »

. . . when you say check the cabinets for leaks do you mean where the wood joins?

Yes.

. . . how does one test for this or is it something to just treat? I have some spray stuff we use for repairs that is for sealing leaks in wood joints.

You are doing a visual inspection on the cabinet joints which should generally be sound if the speakers were cared for properly. When drivers and speaker cable openings are gasketed and you gently depress the passive, you should have approximately 3 seconds of mid woofer extension time. If not, you probably have a cabinet joint leak. I've personally never had a cabinet joint leak.

. . . tweeter at ear level when possible

Correct.

littlewoodboats

I am not anticipating any cabinet issues but will look while the drivers are out for the new gaskets and tweeter swap. I am hoping the gaskets solve the leakage. I have some spray stuff that we use for repairs that is a rubber base for use on wood. It goes on and bubbles up a bit then settles. Assuming I can get to everything it would only take a minute to spray. (if I am in there anyway why not?)

My SDA's are the blade blade connector with a base built onto the bottoms. I looked when I picked them up and think I will have to make corner blocks to mount spikes. Do the spikes care where they are located under the cabinet? To get the tweets to ear level they need to come up almost ten inches. Maybe a new base with spikes? The woodworking is easy enough and I have access to great materials. I was planning a White Oak veneer so bases at the same time would be no big deal.

My biggest problem right now is I have been reading threads like this one.

http://www.polkaudio.com/forums/showthread.php?28959-SDA-2B-Studio-Crossover-Upgrade&highlight=SDA+crossover+upgrade

F1nut

Do the spikes care where they are located under the cabinet?

They are best near the corners.

To get the tweets to ear level they need to come up almost ten inches.

Are you sitting on a bar stool or what?

I removed the base on a pair of 2B studios, added 2" high spikes at the corners and they are close enough to ear level when sitting on a sofa.

F1nut

Do you guys feel that I would get better sound with spikes versus glides if the spikes must be used with discs?

Absolutely.

littlewoodboats

F1nut wrote: »

Are you sitting on a bar stool or what?

No bar stools. I was surprised by the amount of difference myself. Looking at them from across the room I can see they are low but I guessed three or four inches tops. I have a bad hip so I stay away from the lowest chairs but they are not so tall that anyone has complained about not being comfortable. I measure 35" from the floor to the center of the tweeter and 44" to my ear in one of my office chairs. I am 6'3" barefoot.

PreCd

littlewoodboats wrote: »

I am 6'3" barefoot.

Yep.........definitely from Texas.