Quick build SDA 2b Crossover electrolytics and polyswitch resistor replacement images.

VSAT88

Here are some images from a quick crossover re build I took yesterday:

Before Image:

Measure leads, new resistor instead of Poly switch.

Old Caps still measure well. Great parts in Polk Speakers ! 40.0 uF Cap.

20.0 uF Cap ! (old one)

Measure 40.0 uF lead solder points. Helps me bend new ones correctly for easy installation.

Leads 40.0uF Soldered / Alligator Clip Heat Sink for Soldering:

Electrolytic Caps. New Leads Wrapped:

Wrap next to 40.0 uF Cap on new resistor to insulate. Actually they are no where near touching. Safe than sorry...

Installed new Mills 0.5 Ohm Resistor. Nice high quality part !

Crossover completed..For now anyway...

Cool, Carbon dated !! Sep. 8th 1987 !!


Hope I posted correctly Admin if not school me please ! Thanks all.
Post Script...
Disclaimer : I am not suggesting that anyone should use this as a guide...

pitdogg2

Maybe I'm missing something but why put in NEW electrolytic's? If i'm going to take it apart I'm going to use better film caps.....JMHO

VSAT88

pitdogg2 wrote: »

Maybe I'm missing something but why put in NEW electrolytic's? If i'm going to take it apart I'm going to use better film caps.....JMHO

I was expecting that I would be asked that question. I did not have the money at the time to order better film caps. however old and dry was not a great option either. I have a limited income as I am retired but I enjoy piddling around and in time there will be more and more upgrades. I always have to do my upgrades a part by part . These speakers need a lot of work. All of the drivers will need to be replaced and I will probably buy them one or two at a time as well. I have more time than money and doing it this way really does give me something to look forward to. I appreciate you looking ! With regards, Jim.

RandyCroissant

As long as your having fun that is all that matters. By the way the pics are really good.

PolkieMan

And wait for that sale at Sonic Caps. It's only twice a year I think.

VSAT88

PolkieMan wrote: »

And wait for that sale at Sonic Caps. It's only twice a year I think.

This website ?? http://www.soniccraft.com/index.php/sonicap-gen-c-301_49_50

VSAT88

RandyCroissant wrote: »

As long as your having fun that is all that matters. By the way the pics are really good.

Thanks ! And yes this is the best hobby ever !

pitdogg2

yes that is the site they are worth every dime. I completely understand pal they are pricey but oh so sweet sounding when done after a few hundred hours of playing. Do not be surprised if they sound bad/funky now after you new caps it is the nature of the beast there will need to be some break in. Trey at VR mods has some newer boards that make it much easier to get bigger film caps to fit the board better. The newer boards were around 100$. Why new drivers are they scratchy? Polk still supports them and there are new drivers for them they look a little different buy sound the same.

They Sonicaps are tried and true and the clearity caps have a good following also tried and true also there are some other that will not be a very good choice.

Clearity web site
http://www.claritycap.co.uk/

Solen's can be ok for low pass but very hard on the ears for the high pass.

RandyCroissant

I am now gathering the items to build new crossovers Gimpod / VR boards Janzen / Erse inductors, I am going to reuse my Sonicaps as they are great probably reuse my mills resistors as well. At this time I will do the other recommended mods as others have done with good results.

VSAT88

pitdogg2 wrote: »

yes that is the site they are worth every dime. I completely understand pal they are pricey but oh so sweet sounding when done after a few hundred hours of playing. Do not be surprised if they sound bad/funky now after you new caps it is the nature of the beast there will need to be some break in. Trey at VR mods has some newer boards that make it much easier to get bigger film caps to fit the board better. The newer boards were around 100$. Why new drivers are they scratchy? Polk still supports them and there are new drivers for them they look a little different buy sound the same.

They Sonicaps are tried and true and the clearity caps have a good following also tried and true also there are some other that will not be a very good choice.

Clearity web site
http://www.claritycap.co.uk/

Solen's can be ok for low pass but very hard on the ears for the high pass.

Both MW 6511 SDA drivers were bad / scratchy or bottoming out unfortunately. I was going to source new or used 6511 SDA drivers first then put in new higher quality Caps, as well as build a respectful SDA interconnect. That website is like a candy store for a three year old to me ! I don't see anything there I don't want !! They even have new light bulbs for my valve amps !! OH MY !

VSAT88

Oh, BTW one MW 6510 and both SL 2000z were bad as well. These speakers were treated badly by priors. I just happen to love Polk well enough to keep some basic items "in stock" for my RTA 8t and that was a saving grace when I apprehended these...

VR3

I like your adventurous side.

When you are ready I will cover half the cost of your parts if you decide to go with Clarity Cap PX/Solen/Mundorf Mox. So parts less 50% + shipping

Enjoy

leftwinger57

VSAT88,I was asked the same thing when I did my 2B x-overs and sending them out. I just couldn't afford the Ferrari of caps and resistors so Trey hooked me up w/ something that was better than my 28 y/o cross overs. I did all the mechanical mods myself but those I chose to send out and he did very well by me. Would I have heard any difference w/ Sonicaps and the rest of the best, I have no idea and now I really don't care they just sing out.

VSAT88

VR3 wrote: »

I like your adventurous side.

When you are ready I will cover half the cost of your parts if you decide to go with Clarity Cap PX/Solen/Mundorf Mox. So parts less 50% + shipping

Enjoy

That I think is one of the nicest things that anyone could have possibly offered. I do thank you ! In time I am sure I will go for another, better upgrade however unless you work at one of the sites that carry the above and can get a discount that way there is no way I could take you up on the offer. I will just have to save up ! Thanks again !! Oh, BTW I was thinking of Clarity Cap. sure dont want to start a one Cap. is better than another Cap. "war" but what do you think ?

VR3

I am a Clarity Cap/Solen/Mundorf (and many other) dealer. No worries, whenever you are ready but preferably all at once

pitdogg2

Trey's the man around here very experienced and just don't toss offers out like that to everyone. He means what he say's and say's what he means:)

VSAT88

VR3 wrote: »

I am a Clarity Cap/Solen/Mundorf (and many other) dealer. No worries, whenever you are ready but preferably all at once

In that case it seems as if you have a life long customer. I really do not know how to thank you enough !!

PolkieMan

looks like a 1/2 price sale on some going on??? http://www.soniccraft.com/index.php/sonicap-m-21?osCsid=vghr51ria2d7a9go7gqe1t87i1

VSAT88

170.00 not including shipping for 6 Caps. (I would need two for my two 20uF and four to make up my two 40uF). That is a great sale and thanks for letting me know but it will be a good long while before I could afford that...Or, I could sell some gear..

PolkieMan

You could email them and ask to make the uf you need, it may be cheaper but probably not.

VSAT88 wrote: »

170.00 not including shipping for 6 Caps. (I would need two for my two 20uF and four to make up my two 40uF). That is a great sale and thanks for letting me know but it will be a good long while before I could afford that...Or, I could sell some gear..

F1nut

Sonic Craft does not nor will they make a 40uF, the largest is 34uF.

PolkieMan

It has made sense to me to replace them because the speakers are so old and knowing that when manufacturing something you have to save money somewhere.
I just thought that film caps wound be better quality than the old style electrolytic.

westmassguy

kevintomb wrote: »

pitdogg2 wrote: »

Maybe I'm missing something but why put in NEW electrolytic's? If i'm going to take it apart I'm going to use better film caps.....JMHO

"Upgraded" capacitors, are a highly debated item. It is not universally agreed upon that they provide a benefit. On many forums there is a lot of disagreement over them.

With that being said, I almost always use better Grade caps, unless they are very large value and replacing aging electrolytics in the woofer circuit.

Some very well respected speaker designers, swear by electrolytics, so we can not discount their professional experience either.

Some conserve by replacing only those Caps that are defective, some rebuild with like parts, and some prefer to upgrade to better quality Caps.
Large value Metal Film Caps can be quite expensive compared to NP Electrolytics.
Electrolytics are almost always used to keep manufacturing costs down.
Unlike Metal Film Caps, All Electrolytics will eventually dry out and fail. Their tolerances are quite loose as well, most are + or - 10%, some even as high as +10, -20%. That kind of variance can be audible from one speaker to the next, unless they're carefully matched at the factory. Even then, they will eventually drift due to age, so matching becomes irrelevant after 10 -12 years of use. Metal film Caps do not drift, or fail, unless subjected to over-voltage or some other operating condition they were not designed for.
I speak from personal experience. Replacing the NP Electrolytics in the Lo-Pass shunts, and Sub Bass Drive circuits in my 2As, resulted in Bass that is light years ahead of what it was. Other Crossovers I've rebuilt, where Electrolytics were used in series with the drivers, resulted in dramatic improvement. Even entry level Metalized Polypropylene Caps will beat Electrolytics for SQ.
Just my opinion of course.

VSAT88

My opinion only.... replacing the electrolytic caps. in this mid woofer circuit with cheap modern electrolytic caps. led to a tighter sound overall as far as bass is concerned with no effect in the treble area. This was a poor "upgrade" to my ear. I lost low end. In fact as I see it now I wish I had left the old 40uF and the old 20uF in. When I think this whole thing over and see that Polk designed these speakers with electrolytic caps. it makes me wonder if this was simply a cost saving measure. I kind of doubt that. These guys seem to have known what they were doing. I also believe that just about any part can be made "better" or at least upgraded to some extent. Does the better or upgraded part lead to better sound ? I think that would go hand in hand with the listeners ear. I could see that a more tightly controlled signal could be useful in the SDA circuit. I will go with poly. caps. in time. Now, which ones ? Answer.. who knows. I love to experiment and I have the time so I will probably try three or four different sets of caps. After these cook for a while who knows things may well change for the better with them. I have read that changing one thing at a time is a good idea to see if I am marching forward or backward and this makes sense. There were a number of issues with this pair of $80.00 speakers when I got them including both poly switches bad, both tweeters bad and one 6511 bad. That is not to mention the overall poor look of the cabinets. Adding the 0.5 ohm resistor, a good used MW 6511, a home made SDA Interconnect and the new electrolytic caps is all that I have done so far however that is just a start. In time I will do more and more because I like these speakers. Time and money is what it will take to slowly bring them into line and make them my keeper mains for my office/dungeon. Please keep this in mind..I have only re capped about 8 sets of speakers and I have used all over the board parts so I truly am a newcomer.

F1nut

When I think this whole thing over and see that Polk designed these speakers with electrolytic caps. it makes me wonder if this was simply a cost saving measure. I kind of doubt that. These guys seem to have known what they were doing.

There wasn't much of a choice back then.

pitdogg2

F1nut wrote: »

When I think this whole thing over and see that Polk designed these speakers with electrolytic caps. it makes me wonder if this was simply a cost saving measure. I kind of doubt that. These guys seem to have known what they were doing.

There wasn't much of a choice back then.

Bingo and what there was for film caps was way out of the ballpark in price.

look if Polk could save 30cents per cap it doesn't seem like much until you look at 50,000 caps times .30 which right here would be 15,000$ savings.....

VSAT88

I found that most of my problem was being caused by a bad pre amp. The speakers sound pretty great now that I replaced it. It was a Kenwood C2 and is now in line for a refurbish..

VSAT88

kevintomb wrote: »

VSAT88 wrote: »

My opinion only.... replacing the electrolytic caps. in this mid woofer circuit with cheap modern electrolytic caps. led to a tighter sound overall as far as bass is concerned with no effect in the treble area. This was a poor "upgrade" to my ear. I lost low end. In fact as I see it now I wish I had left the old 40uF and the old 20uF in. When I think this whole thing over and see that Polk designed these speakers with electrolytic caps. it makes me wonder if this was simply a cost saving measure. I kind of doubt that. These guys seem to have known what they were doing.

Are you talking about the "Shunt" caps across the woofer circuit?

If so, their function is to "Bypass" high frequencies around the woofer, and in combination with the inductor provide a 12/db/octave roll off of the highs.

I am not sure how that would affect the low end response though. The inductor could have some impact due to DCr values, but a shunt cap by its very nature, is only shunting frequencies above a certain range past the woofer.

You may be experiencing a different top end roll off on the woofer though.

Yes, the shunt caps across the woofer circuit.

F1nut

replacing the electrolytic caps. in this mid woofer circuit with cheap modern electrolytic caps. led to a tighter sound overall as far as bass is concerned with no effect in the treble area. This was a poor "upgrade" to my ear. I lost low end.

Tighter bass does not mean you lost low end, although the caps do need to burn in, so you need to let that happen.

Shunt caps DO make a difference and Sonicap makes for an excellent shunt cap.