Building a set of SDA's

backinthelou

Hi fellas,
I came to this forum because I recently picked up a pair of SDA II's. I actually went out to a guys house to look at some other vintage stuff that his wife was making him get rid of. I honestly never really new of any vintage hi end speakers, but have been quickly learning over the past couple of months. Anyway, I was looking over some stuff he had and he offered me these SDA's for $50. I wasn't too impressed with them because we were in his cluttered basement and he was using crappy old lamp wire that he was stripping with his teeth....lol. He fires them up and they sound mildly mediocre. I figured I could get them to sound at least a little better with something I had at home so I loaded them up and brought them home.

HOLY COW!!! I am absolutly in love with these speakers. They are the ones with 1 tweeter, 2 mids and a PR. They are the nicest speakers I have ever heard, and I've listened to alot of newer stuff.

Long story short, I have some older cabinets that are in really nice shape. I've gutted them and would like to make some mini SDA's. The cabinets are about 24"X 14"X14". I have a line on all the internal parts except the mid drivers. Can I still get the mids new from Polk? I know there are people that will tell me to just buy some SDA CRS's, but I'd really like to try this. I am wondering if I am going to be screwwed up on air space. Are the crossovers different on the CRS's? I know they use a smaller PR. Anything else I should know?
Thanks

jimbo1421

Before you go tearing up the nicest speakers you have ever heard you would do well to study up on their special properties and how they work. Here is a good start: http://www.polkaudio.com/downloads/whitepapers/SDA_WhitePaper.pdf

Jim

backinthelou

jimbo1421 wrote: »

Before you go tearing up the nicest speakers you have ever heard you would do well to study up on their special properties and how they work. Here is a good start: http://www.polkaudio.com/downloads/whitepapers/SDA_WhitePaper.pdf

Jim

My mistake. I am not tearing up the ones I have. I want to build some other ones but in a smaller cabinet with parts I can acquire pretty cheap.

Toolfan66

Then I say knock yourself out...:)

heiney9

I predict by the time you're done, they won't sound like SDA's and you'll just purchase a pair of CRS's which is what I suggest you do to begin with.

But hey, knock yourself out.

When you say "with parts I can acquire pretty cheap". What does that mean? Polk parts? or random other manufacturer's parts? you going to use old CRS crossovers? Those are the only ones that will really work and that's if you build the cabinets to the exact specifications and use the drivers used in the CRS's. Of course there is more than one model CRS and they are both quite different so be sure the parts are all from the same model.

If you're not going to use Polk parts or cabinet dimensions, forget it.

Have fun, rock on.

H9

backinthelou

I will be using all Polk SDA 2 parts-including crossovers. The only parts I will not have are the mid drivers. Can I get those from Polk?

heiney9

backinthelou wrote: »

Anything else I should know?
Thanks

There's a LOT you should know..............most of it is proprietary information that Polk doesn't share.

H9

Vette C6.r

Yes but they do have a different look to them. No exactly the same as the orginal MW XXXX.

Sounds like an uphill battle. I would say get bigger SDA's if you want a bigger soundstage.

heiney9

backinthelou wrote: »

I will be using all Polk SDA 2 parts-including crossovers. The only parts I will not have are the mid drivers. Can I get those from Polk?

When you say SDA 2, which SDA 2? There were several generations all slightly different in the tweeter and drivers they used as well as the x-over.

How are you going to be sure the cabinets you have are the correct volume or that the baffles are cut at the proper dimensions? You do know the drivers in the front baffle aren't flush, they are a slight angle and the center to center point of each driver is critically important.

H9

Toolfan66

The feedback your getting is great feedback, and true. But I still say if you have the parts and don't mind killing time to do so. Then I still say knock yourself out!!!

Have fun, if it don't work then sobeit you still have the extra parts..

backinthelou

I don't want to crack mine open, so does anyone know if the SDA cabinets are just a big open box or is there any port work inside? Thanks again for the comments.

heiney9

No port work, the Passive Radiator is the port. See, this question worries me because it's obvious you don't have a lot of knowledge about speaker design. The large speaker is a Passive Radiator which acts like a port. It's not powered and they are tuned to the cabinet and the drivers by way of weight. Adjusting the weight on the PR changes the tuning frequency.

You can NOT use a ported cabinet for SDA's.

H9

fishbones

Not to be a downer, but unless you were one of the original engineers with Polk creating the SDA's, I think you're going to waste you time and money. You're talking about something that is on a completely different wavelength of loudspeaker engineering, dealing with time-aligned frequencies (out of the normal realm), crossovers designed to work completely different than normal, etc, etc. Better off putting that money into the 2b'S that have all the engineering done already, and just improving on the platform you have. It will take them to a whole new level....my 2 cents.

This thread is on the 1C's, but gives a big picture view of how to do it, by an excellent member (TOOLFORLIFEFAN)...
http://www.polkaudio.com/forums/showthread.php?t=97719

backinthelou

heiney9 wrote: »

No port work, the Passive Radiator is the port. See, this question worries me because it's obvious you don't have a lot of knowledge about speaker design. The large speaker is a Passive Radiator which acts like a port. It's not powered and they are tuned to the cabinet and the drivers by way of weight. Adjusting the weight on the PR changes the tuning frequency.

You can NOT use a ported cabinet for SDA's.

H9

I'm not an idiot either. This is why I am taking suggestions. I have alot of experience in alot of different "things". I understand that these are special speakers with crossovers designed for a specific purpose. When I say "port work" I am refering to internal, as in from one part of the speaker(mids) to another(PR)). My point is that I will have these parts and short of finding the original cabinets, would it be an awful idea to use these tweeters, crossovers and PR's in something else? I do have a background in avionics. I have done several car audio installs and am not some bozo trying to ruin a set of nice speakers. BTW, I know you can't use PR's with a port.

heiney9

Sorry backinthelou, didn;t mean to imply you were an idiot. knock yourself out, I'm outta this one.

H9

fishbones

backinthelou wrote: »

I'm not an idiot either. This is why I am taking suggestions. I have alot of experience in alot of different "things". I understand that these are special speakers with crossovers designed for a specific purpose. When I say "port work" I am refering to internal, as in from one part of the speaker(mids) to another(PR)). My point is that I will have these parts and short of finding the original cabinets, would it be an awful idea to use these tweeters, crossovers and PR's in something else? I do have a background in avionics. I have done several audio installs and am not some bozo trying to ruin a set of nice speakers.

Well, if you can figure it out...kudos to you, but I don't think too many on here could tell you how to do it accurately, and there is alot of talent on here - quite a few have revamped countless SDA's, and I don't think they would tackle something like that. But good luck, let us know how it goes....

jcandy

backinthelou wrote: »

My mistake. I am not tearing up the ones I have. I want to build some other ones but in a smaller cabinet with parts I can acquire pretty cheap.

The general advice that one gives to a first-time builder is to start with a simple MT (mid-tweeter 2-way) design. Furthermore, to have any sort of chance of building something that doesn't sound worse than what you'd get for $50 at Best Buy, you will need measurement equipment and design software. Attempting to build a system with an SDA-type crossover, as others have said, would almost certainly be hopeless.

In fact, an ever better way to start -- one that will save you from buying measurement and design equipment -- is to build an existing, well-documented design. In this respect, Zaph is my favorite:

http://www.zaphaudio.com/

Joe08867

jcandy, That is some good advice. SDA's are in a whole different world of audio tech. I don't mind tweaking on them but to start from scratch would be tough.

But sometimes it is fun to just give it a whirl. You never know, it might just be better than sliced bread. Didn't Ben build a set??? Albeit not small ones.

heiney9

Ben knew what he was doing to a certain degree because he did a lot of research and talked to Matt Polk and other Polk engineers. He ended up tweaking them for over a year and still never got them exactly right. I believe he then tore them apart and sold off the parts. Probably the best effort to date.

H9

Toolfan66

All the guy wants to do is build a cabinet and put SDA parts in it. I really don't see the harm in it. He isn't asking about building a set of SDA's from scratch. he even has the extra SDA parts other then the drivers to do so.. Now if he was going to trash a good set of speakers to make it happen then I would think otherwise..

Can people read the whole thread before jumping???

Dude again, if you don't mind the time and money GO FOR IT!!!

heiney9

backinthelou wrote: »

Long story short, I have some older cabinets that are in really nice shape. I've gutted them and would like to make some mini SDA's. The cabinets are about 24"X 14"X14". I have a line on all the internal parts except the mid drivers. Can I still get the mids new from Polk? I know there are people that will tell me to just buy some SDA CRS's, but I'd really like to try this. I am wondering if I am going to be screwwed up on air space. Are the crossovers different on the CRS's? I know they use a smaller PR. Anything else I should know?
Thanks

Hmmmm Larry, seems he wants to build them from scratch to me.

Just giving him some advice, I don't care one way of the other what he does.

H9

heiney9

backinthelou wrote: »

My point is that I will have these parts and short of finding the original cabinets, would it be an awful idea to use these tweeters, crossovers and PR's in something else? .

Now here it does seem he just wants to use the parts, I have no idea what "something else" is as he states.

H9

Toolfan66

backinthelou wrote: »

Long story short, I have some older cabinets that are in really nice shape. I've gutted them and would like to make some mini SDA's. The cabinets are about 24"X 14"X14". I have a line on all the internal parts except the mid drivers. Can I still get the mids new from Polk? I know there are people that will tell me to just buy some SDA CRS's, but I'd really like to try this. I am wondering if I am going to be screwwed up on air space. Are the crossovers different on the CRS's? I know they use a smaller PR. Anything else I should know?
Thanks

Toolfan66

heiney9 wrote: »

Just giving him some advice, I don't care one way of the other what he does.

H9

I know, and your advice is good advice, I agree with you for the most part. But I also think its ok to give it hell if one wants too,,:p

backinthelou

I have some vintage UTAH cabinets in a walnut finish. I removed all of the drivers and will sell them off to someone that would like to have them. They are all in perfect condition, but they aren't pleasing to my ear.

I am about to purchase the guts minus the mid drivers from a set of SDA 2's. The cabinets I have look similar to the size of the CRS cabinets, so I was thinking of transplanting the SDA guts into a set of cabinets that are about the size of the CRS cabinets(the UTAH cabinets I already have).

I am not modifying the SDA 2's that I already have, except for maybe doing some forum suggested upgrades in the future.

If this is a terrible idea, I will use traditional drivers in the UTAH cabinets that I have.

heiney9

backinthelou wrote: »

I have some vintage UTAH cabinets in a walnut finish. I removed all of the drivers and will sell them off to someone that would like to have them. They are all in perfect condition, but they aren't pleasing to my ear.

I am about to purchase the guts minus the mid drivers from a set of SDA 2's. The cabinets I have look similar to the size of the CRS cabinets, so I was thinking of transplanting the SDA guts into a set of cabinets that are about the size of the CRS cabinets(the UTAH cabinets I already have).

I am not modifying the SDA 2's that I already have, except for maybe doing some forum suggested upgrades in the future.

Good luck, have fun. They won't sound anything like CRS's or SDA 2's. But, if you are just looking to experiment and mess around.......rock on.

Depending on which model SDA 2's you are using for parts (you still haven't stated if they are SDA 2's, 2A's, 2B's which are blade/blade or 2B's which are pin/blade) Polk might carry the new drivers. These models used slightly different MW drivers for each generation. The cost as a Club member is $48/ea plus shipping so just for the new drivers it's around $210, if they are the models you need.

H9

heiney9

Do you have any idea what the model of the drivers are that are missing from the guts you are getting from the pair of SDA 2's?

MW6500
MW6501
MW6502
MW6503
MW6510
MW6511

Some SDA's used the same model drivers for both the stereo driver and SDA driver and some used different drivers for each. This is info you will need to know when getting the guts from a pair of SDA's.

H9

Polkersince85

If you are going to build, why not duplicate the SDA 2 cabinet using MDF? It may sound more like a SDA 2. I don't think you will be successful using a Utah cabinet.

backinthelou

heiney9 wrote: »

Do you have any idea what the model of the drivers are that are missing from the guts you are getting from the pair of SDA 2's?

MW6500
MW6501
MW6502
MW6503
MW6510
MW6511

Some SDA's used the same model drivers for both the stereo driver and SDA driver and some used different drivers for each. This is info you will need to know when getting the guts from a pair of SDA's.

H9

Thanks alot for the cross reference numbers H9. I've not had any luck finding info as far as replacement parts. I do not have the "spare" parts that I am picking up yet, so I couldn't tell you what they came out of. Hopefully, when I get them, you guys can help me figure out what I have. Polker, that may be a very good idea. I have all the required tools. I have tossed the idea around of using these UTAH cabinets and maybe use a 10" radiator instead of the 12", but if there are alot more internal differences, it seems that it may not be worth it. Do any of you know the differences in the crossovers for the different models specifically the SDA 2's and CRS's? Thanks again.

If I do make new cabinets, I could have an extra set of 2A's for minimal cost.

halo71

backinthelou wrote: »

If this is a terrible idea, I will use traditional drivers in the UTAH cabinets that I have.

Even though many here will tell you that you are crazy for wanting to do this. I guess not many are as adventurous with DIY stuff. But upgrading the drivers and XO's in your Utah's....and Ken's advice of rebuilding some regular SDA's to me seem the best advice so far.

I have a old set of Utah's and aside from the drivers being pretty crappy. The cabinets whistle like a shutter in a wind storm. And are not braced internally at all. So for getting your feet wet for the first time with speakers. Hit parts-express.com for drivers, XO's, Mortite etc. And hit Lowe's for some lumber to brace them cabs up.;)

heiney9

backinthelou wrote: »

If I do make new cabinets, I could have an extra set of 2A's for minimal cost.

You really don't want 2A's. If you're going to spend the sweat and money you'd be better of with a TL'd pair of Pin/Blade 2B's. That is the most desirable SDA 2 model.

H9