SDA SRS rebuild ?

apachef1

I'm planning out a crossover rebuild for my SDA SRS speakers and I have been reading bits about the 2-750uf caps being removed all together and the circuit just wired through without any issues in sound. Are these the caps that protect the tweeters from an amplifier thats being driven into clipping? Or are they there for some sonic purpose?

ED

avguytx

They are used in conjunction with a lesser grade cap of some sorts and are supposed to emit the sonic characteristics of the "better" cap and would be more cost effective in a major run of any given model of speakers. When doing crossover upgrades, most any (of us) don't use them again as we are using a better grade poly capacitor from Solen, Sonicraft, etc. You might be thinking of the poly thermal switch, too, which some will remove, some won't. It's used to absorb some of the extra energy and when the plates inside get hot enough, they separate making the tweeter shut off until it dissapates some heat. You can leave those out, too, BUT you want to make sure you have plenty of clean power and are not driving at insane levels. ESPECIALLY with too little of power on those SRS's.

Someone with the SRS's or 1.2's etc will chime in soon and can give great advice. Keep searching/reading the various posts on the crossover upgrades. Lots to be learned!

avguytx

See? I told you someone would chime in.

Sal is the shiznit of all shiznits.

apachef1

So I understand, The 750pf caps are also known as polyswitches?
I have no problem as far as power is concerned. 500 watts/ch of pure tube power and I drive them like a baby carriage. I will be using very high quality Duelund copper foil caps and Resistors along with new main inductors.

What do you polkies recommend for the 92uf and 130uf caps? Duelund does not make these values and it would not be economical?

F1nut

NO! The 750pF bypass caps are not polyswitches.

avguytx

Dueland? Sheesh...those things are expensive! How much better are they than Sonicap, Auricap, Solen, etc? Are they all only rated at 100v?

apachef1

Bare with me on this. Which ones are the poly switches? I'm not doing the work, I have an A'goner who does crossover upgrades on the side. I need to talk to him about all this intelligently and gather info from you guys who have done this work. I've done allot of searching on the Polk forum and have gather a ton of info. I'm trying to clear up some grey area's. How do you Identify the polyswitch? Nothing is marked clearly on the crossovers

ED

avguytx

See that little tan disc shaped piece kind of under the green wire and on top of the yellow poly cap? That's the poly switch. That little black odd shaped cap wired in with the yellow poly cap is the 750pF bypass cap.

This is the stock crossover from my 1C's. Sorry for the cruddy picture...I had to crop it.

Edit: Found a better picture. It's the tan disc right there in the front. They'll look similar on yours but just in a different location since it's a "board" layout.

F1nut

Allow me to comment further. Duelund caps are very, very expensive. You'll end up spending more than the speakers cost new. Just a quick calculation, not including the 92 and 130uF caps comes out to $3036.00. Again, more than the speakers cost when new. It's your money, but IMO it's a total waste. If Sonicaps aren't good enough, try Mundorf's. Still a lot of money, but far less than Duelund.

What tube amps do you own?

The polyswitches are small discs, either mustard yellow or medium blue in color.

apachef1

Duelund's are rated at 250v These are specifically designed for loudspeakers.
The Polk SDA SRS & 1.2 & tl's are a speaker with an unbelievable sound stage that are not fatiguing at all. The Duelund's will make these compete with all the top speakers without the 100k price tag. The Duelunds will also clean up the bass of the SRS. tends to be a little on the "thick" side. I also plan on changing the hookup wire to 15 gauge kimber along with the binding posts.
These puppies are going to be as good as it gets.

avguytx

Wow...that's some "jack" to lay out on crossovers. I hope you are upgrading those SL2000's (?)to the RD0 tweeters as well. That will seem like a minimal expense alongside those Duelands!

I guess the ones I saw that were 100v were from Partsconnexion.com's website. Those were the only copper foil caps I saw.

F1nut

Ok, for my own amusement, if you include the 92 and 130uF caps, your total for caps alone will be about $7525.00.

As much as I love SDA's, you're still not going to have a $100k speaker.

I'm sorry, but I have to call BS on this one.

F1nut

BTW, your McIntosh MC3500's put out 350wpc, not 500.

apachef1

I have a pair of mint McIntosh MC3500 mono blocks driving them. A very rare tube amp.
As far as the Duelunds, they are going to need a very high quality amp to make them really perform. The cost just for parts is going to be around 3600.00 with the inductors. When you break it down to 2007 $$ The Polk would cost over 10k if they were in production today from the factory. For around 5k I will have a pair of speakers that will bring me as close as it gets to a live performance "being there effect". How many speakers do you listen to in the audio shop that sound nice great bass very detailed but?? The "being there effect" is just not there like the polk's

apachef1

mc3500 are rated at 350watt/ch continuos on the bench they were at 483 and 479 @ 1% distortion I'll never drive them that hard. They are a different animal altogether, hard to explain.

F1nut

Please read this as I don't think you understand that Duelund caps are not meant for speakers like SDA's, which are anything but simple crossovers.

"These cost no object products are certainly very expensive, but they are designed for those with simple crossover topologies in need of minimum coloration components. Perfect for full range drivers with simple equalization circuits or for simple 2way designs."

They are a different animal altogether, hard to explain.

Not really.

F1nut

What do you polkies recommend for the 92uf and 130uf caps? Duelund does not make these values and it would not be economical?

The Duelunds will also clean up the bass of the SRS.

It's going to be kinda hard for the Duelund's to clean up the bass if you aren't using them in the low frequency circuit, eh?

apachef1

Easy dude you seem a little argumentative. Just looking for some info. The Duelund inductors are going to be used in the bass driver area. Didn't realize you were going to get defensive. I believe you were the same guy bad mouthing me when I was looking for a pair of SDA's on the forum??

HHMMMM

apachef1

BTW Duelund have been used in Dunlavy 4 and 5 A crossover that is more complicated than polk's

F1nut

apachef1 wrote: »

Easy dude you seem a little argumentative. Just looking for some info. The Duelund inductors are going to be used in the bass driver area. Didn't realize you were going to get defensive. I believe you were the same guy bad mouthing me when I was looking for a pair of SDA's on the forum??

HHMMMM

Defensive? Hardly. I'm just trying to talk some sense into your thought process. It doesn't seem to be working.

Bad mouth you? Nope, that wasn't me. In fact, I offered you help twice before this thread.

Which brings up this diddy.

apachef1 wrote: »

Hey luc,

It's around 600.00 to ship plus crating. Not really economical. Thanks anyway.

ED

So, $600.00 for shipping is too much, but $5 to 10k for a full out upgrade isn't? Yeah, ok.

Sorry to burst your bubble, but again I have to call BS on this one.


So, you don't know what a silver mica is, but you're sure that a Dunlavy crossover is more complicated than your SRS. Not to mention the real estate nightmare of remote mounting those caps inside your speakers. Think again.

Bottom line, I'm trying to save you a lot of money and from making a huge mistake. Take my advice or don't, I'm done here.

apachef1

My bad and I apologize you were not the one bad mouthing me. I had to look back a little and I was getting a hard time on this site even looking for the speakers here.

I was trying to see why you are so down on the Duelund caps other than a price issue. This whole subject kinda sparked you off. I wasn't trying to pick a fight just get some info on the crossover itself..

The quote you posted is a reviewers opinion and not an actual manufacturer recommendation. Take a look at a Dunlavy 5 crossover almost twice the amount of components in those puppies. Twice as much to upgrade with Duelunds than in the Polk's. These behemoth's are getting up in age now.

Soni-caps/mills definitely work well with the Polk's and are economical to use. Everyone is using them, why not try a to step it up and really open the babies up is all I'm suggesting. Is 3000.00 really allot to spend on an upgrade. Not really if you were to look at what it costs to upgrade CD players like a Wadia. What sonic benefit do you really get, very little return on the sonic dollar. But a crossover upgrade will give you allot more sonic benefit for the dollar than any cable/interconnect or component upgrade. Even the so called best speaker manufacturers still use low quality crossover parts in their 100k plus speakers. 100k for a pair of speakers and 30.00 in crossover parts inside them. Now that seems like a huge waste of money to me. What you dont see you dont get.

You have made some valid points that I am definitely considering. But for me I have well chosen high end components that all do what each one does best. The Polk SDA SRS family is a speaker that seems to do everything well and some thing exceptional well. (Could have been built a little more solid) I just thought bringing them 20 years forward would be a very interesting and pleasurable experience.
No hard feelings f1nut

Cheers

treitz3

Squeeze just two more posts in and you can sell what you want. Good luck getting any buyers.:rolleyes:

apachef1

F1nut doesn't want to talk anymore. Oh well. I didn't come here to talk about Deulund or McIntosh; I was looking for help to identify a couple of components on the crossover grid. Thank you to the polkies that did provide me with the valuable info I was looking for including you F1nut.

ED

F1nut

Nope that's not it. I simply haven't been online since last night and I did say that I was done here.

Anyway, no hard feelings here either.

danger boy

spending that kind of cash is pretty much throwing away money IMHO. seriously.. you could do better.

why put a Jaguar engine in a Toyota car? Not saying that the SDA's are bad at all, but think of how dumb that would be.

It is your money..and you can do whatever you like to your speakers.. but if it was my money.. i'd spend it instead on new speakers.. something more modern lets say.

DarqueKnight

apachef1 wrote: »

The Duelunds will also clean up the bass of the SRS. tends to be a little on the "thick" side.

Higher quality crossover parts will improve the bass performance of the SRS. However, you should be aware that Polk addressed the bass "thickness" of the SDA SRS by going to an improved stiffer cabinet structure in the SRS 1.2 and SRS 1.2TL. The cabinet resonance of the SRS did color the bass response.


I look forward to reading your modification review.

schwarcw

There is a point of diminishing returns. Paying more than a couple of hundred bucks for crossover upgrades will not be a good investment. Get the soft dome tweeters, some Sonicaps, Solens (for real big values) maybe a Mundorf in the right position. If you got extra cash consider upgrading your source(s) or another component. IMHO.:)

dvran

Why not just save a bunch of cash and buy some new Polk LSis with a few SVS subs. There you go, instant SRSs!

~Dan

F1nut

Not even close.

apachef1

The "bass thickness" can be cured easily by going to air core inductors and top quality damping material in the SRS's.

Darqueknight, I'm intrigued by the fact you somewhat agree with my thoughts on this subject seeing you think the SDA is an outdated technology. I agree with you on being outdated, but not in the technology, but the overall parts used. 20 years ago know one talked about doing x-over upgrades like today. You were lucky to get a pair of speakers that had gold plated binding posts.

Again I cant stress how well these speakers can present a sound stage but they do need many upgrades to make them competitive with todays (2007) speakers. Even the last generation 1.2TL's could use added damping and quality internal wiring.

All that really matters in the grand scheme of thing is that know matter how little or how much fat cash you spend on a pair of speakers, amplifiers, and source components, if you're happy with the way they sound every time you flip the switches on to your rig ,sit in front of your babies and they sing to you, then it was money well spent regardless of any other opinions on this forum.

I'm glad I made this post, It really brought everyone together to talk and share ideas. In a strange sort of way, all of us are striving for the same end result. Happy listening to all.


Cheers

ED

F1nut

Yeah, that's why he owns 5 or 6 pair and I own 3 pair. Outdated my hairy white ****! :rolleyes: