Teflon and Polystyrene Capacitors In SDA Speakers.

polktiger

I will admit to not knowing much, but I do have a question for this thread...

How long has the chief engineer, Brad, been with Polk? Since Polk has not really sold any SDAs in many years, has he actually been involved in active engineering of the SDA speakers?

Maybe Brad has been there for 20 years and knows all about SDAs in intricate detail. But he may actually not be intimately familiar with all the engineering of a speaker he no longer sells. (Actually, I hope he spends all his time on current models and not SDAs unless they are planning to reissue the SDA.) By comparison, I doubt NASA's cheif engineer can give you detailed engineering specs of the Apollo lunar landing modual since the project has been dead for many years

danger boy

jakelm wrote: »

So its .....

Best to worse in audio signal

Teflon
Polypropylene
Maylar
Electrolytic

cool. this is more of the info that I would like to see in this thread, with so many of us facing or wanting to upgrade/update our crossovers... i'd like to know which caps are the premium and will give the best sound and which are ones to avoid.

say for instance, I wanted to rebuild the crossovers in my SDA 2B's, which ones should I be looking at? what type did Polk use in them 20+ yrs ago, and what ones are considered to be the best for updating old crossovers... regardless of price. I want my 2B's to be top notch sounding... within reason of course.

heiney9

danger boy wrote: »

cool. this is more of the info that I would like to see in this thread, with so many of us facing or wanting to upgrade/update our crossovers... i'd like to know which caps are the premium and will give the best sound and which are ones to avoid.

say for instance, I wanted to rebuild the crossovers in my SDA 2B's, which ones should I be looking at? what type did Polk use in them 20+ yrs ago, and what ones are considered to be the best for updating old crossovers... regardless of price. I want my 2B's to be top notch sounding... within reason of course.

DB, did you ever get the compendium? All that info is in there, plus since you have the 2b's you should do the 4.1TL upgrade.

danger boy

H9, I do have the Compendium.. it's a great read

i'll be honest, I don't know what the 4.1TL upgrade would involve. I would think new tweeters and crossover mod's

I am running them using the RD0-194's currently.. and once broken in... they sound great now.

ka7niq

jakelm wrote: »

So the Solen Polypropylene is better than the electrolytic, that I replaced in my 7's xover?

But not better than the older Maylar, that I replaced as well?

http://www.partsexpress.com/solen-metallized-polypropylene-capacitors.cfm

An argument can be made two ways in response to your questions.
Capacitor vs Capacitor, the Solens are better/longer lasing then any electrolytic, and better then Mylar too.

Here is where there is a discrepancy.
The crossover filters were designed around the original capacitors.
Change them, and you change the "voice" of the speaker, sometimes for the better, sometimes not.
I have played with and restored many speaker crossovers.
Often times there was a huge improvement in going to "better caps".
B&W does not suggest changing types of capacitors when replacing.
They caution against it.

I have had mixed results changing caps, but have no experience on SDA Speakers.
I did insert a clarity cap in my Polk RT 2000P crossovers, but admit the crossovers were brand new, and I never listened with the stock Mylar.

I have found that new caps of any kind sound better then real old ones.
But sometimes this is simply because the old ones were bad.

I redid some Spica speakers with all Solens and Bennic Polys.
Sounded great.
Just for kicks, replaced all the expensive caps with Electrolytic of the same brand as stock.
Image was much better, and so was the sound.'
WHY ?
Because Jon Bau of Spica USED Electrolytic of a certain brand in the original design.
The crossover was optimized for THOSE Caps.

heiney9

danger boy wrote: »

H9, I do have the Compendium.. it's a great read

i'll be honest, I don't know what the 4.1TL upgrade would involve. I would think new tweeters and crossover mod's

I am running them using the RD0-194's currently.. and once broken in... they sound great now.

Yes, my understanding is a slight x-over reworking and the RD0198-1's for the 4.1TL upgrade. I couldn't remember if you had already purchased the RD0194-1's yet, so you are set. Solen's and Mills should be next on your list, excellent results w/o breaking the bank.

jakelm

So being it s a different cap, it might effect the sound and xover points, so a re/evaluation of the size/value of the cap might have to be done?

Thus by changing the type of cap, the value might have to be changed as well?

If my origianl Maylar cap was 34uF, then by changing to a Polypropylene cap the value might have to be changed to 30uF or 40uF, to get back to the original xover point?

shadowofnight

ka7niq wrote: »

Brad did make a distinction between high end and lower end product.
He said he felt that electrolytics with a mylar bypass were good enough for lower end product.
He prefers film caps for the higher end stuff like the LSI's.
I did not mention SDA speakers as such.
Since you know more about Polk speakers then I do, is there something special about the SDA Speakers ?
They just seem like Polks to me with extra dimensional drivers, some progressive line source stuff, etc.
The drivers seem to be used in other Polks, but I may be wrong ?

Brad did not say this, but I take his suggestions to include the SDA Speakers when he spoke of "higher end product".
How about you or I email him, and ask if I can post his response in the forum ?

There is nothing magical with the SDA's that would make changing out an electrolytic/mylar/poly cap with a teflon cap IF it would improve the same circuit used in a non-sda crossover.

Crossover component selection is like every other selection made pertaining to ANYTHING designed....its based on the almighty $$$$$ You target to your audience price range and build accordingly....guess what...as the speakers increase in price range....better capacitors show up in the crossovers...they know which ones sound better. Polk saved money in the best places possible and the easiest to upgrade......they build very good enclosures and use butyl rubber surrounds even on the entry level lines ( How many foam surrounds last 20 years ...not very many )...and go cheaper in the easiest place to upgrade for better sound.

On the mentioned SDA line....they even took it to the extreme...making extremely well braced cabinets...really nicely designed drivers as well as crossovers that had a lot of engineering and testing time into them. Now if they had used capacitors that cost 29 dollars each instead of 2.90 each...most of us wouldnt have been able to put them in our homes...period. At the time they were out in the market , I could only afford my first set of CRS's and dreamed of the big boys....now I can afford the big boys and upgrade what Polk saved on back then to get them out to the masses...letting me do minor modifications to get them to sound their absolute best.

Polk knew what crossover components sounded best.....they just couldnt use the absolute best components and get them out to the target audience they wanted to address.

steveinaz

This stuff is all about 3 feet over my head, but interesting nonetheless.

ka7niq

polk tiger wrote: »

I will admit to not knowing much, but I do have a question for this thread...

How long has the chief engineer, Brad, been with Polk? Since Polk has not really sold any SDAs in many years, has he actually been involved in active engineering of the SDA speakers?

Maybe Brad has been there for 20 years and knows all about SDAs in intricate detail. But he may actually not be intimately familiar with all the engineering of a speaker he no longer sells. (Actually, I hope he spends all his time on current models and not SDAs unless they are planning to reissue the SDA.) By comparison, I doubt NASA's chief engineer can give you detailed engineering specs of the Apollo lunar landing module since the project has been dead for many years

Really, Matt himself would be THE one to ask.
I considered myself Lucky to even speak with Brad.
I would think Polks chief engineer would be familiar with Polks ex flagship.
The same way a head mechanical engineer at GM Tech Center would be familiar with Zora Arkus Duntov and the old Corvette.

I did not limit myself too SDA type speakers in my conversation with Brad.
The SDA is a dynamic speaker, a lot like it's fellow Polk stablemates.

A good capacitor is a good capacitor, and as long as it's other characteristics like ESR, etc, etc do not throw the crossover filter off, it can sound good on any driver in any speaker, SDA or not.

ka7niq

shadowsofnight wrote: »

There is nothing magical with the SDA's that would make changing out an electrolytic/Mylar/poly cap with a Teflon cap IF it would improve the same circuit used in a non-sda crossover.

Crossover component selection is like every other selection made pertaining to ANYTHING designed....its based on the almighty $$$$$ You target to your audience price range and build accordingly....guess what...as the speakers increase in price range....better capacitors show up in the crossovers...they know which ones sound better. Polk saved money in the best places possible and the easiest to upgrade......they build very good enclosures and use butyl rubber surrounds even on the entry level lines ( How many foam surrounds last 20 years ...not very many )...and go cheaper in the easiest place to upgrade for better sound.

On the mentioned SDA line....they even took it to the extreme...making extremely well braced cabinets...really nicely designed drivers as well as crossovers that had a lot of engineering and testing time into them. Now if they had used capacitors that cost 29 dollars each instead of 2.90 each...most of us wouldn't have been able to put them in our homes...period. At the time they were out in the market , I could only afford my first set of CRS's and dreamed of the big boys....now I can afford the big boys and upgrade what Polk saved on back then to get them out to the masses...letting me do minor modifications to get them to sound their absolute best.

Polk knew what crossover components sounded best.....they just couldn't use the absolute best components and get them out to the target audience they wanted to address.

I can almost hear Matt BEGGING for a Hovland back then, since Hovland was THE cap of that day.

I think it is a prudent idea when replacing caps in 20 year old speakers to admit the old caps are bad.
That is almost a given, especially with electrolytic.
So, why not replace caps with the exact same brand and type, and LISTEN first to get a baseline ?

This will allow you to hear what the designers intended.

Then, if you want, replace with different caps, and listen again.

Far too often, I have just thrown Solens/Bennics in there, and had it sound better.
But upon replacing the "better" caps with the new, stock ones, had it sound even better still.

jakelm

ka7niq wrote: »

I can almost hear Matt BEGGING for a Hovland back then, since Hovland was THE cap of that day.

I think it is a prudent idea when replacing caps in 20 year old speakers to admit the old caps are bad.
That is almost a given, especially with electrolytic.
So, why not replace caps with the exact same brand and type, and LISTEN first to get a baseline ?

This will allow you to hear what the designers intended.

Then, if you want, replace with different caps, and listen again.

Far too often, I have just thrown Solens/Bennics in there, and had it sound better.
But upon replacing the "better" caps with the new, stock ones, had it sound even better still.

I see your point.

And worse come to worse, it would sound the exact same and last another 20 years.

My father's 1977 7a's have not been touched and sound fantastic. I feel alot of times we change out caps , just to do it. For a peice of mind.

I did it because of sonic problems, something was just not right with my 7b's. Now they are fantastic. But a pair like my father's "why mess with it" he says.

ka7niq

steveinaz wrote: »

This stuff is all about 3 feet over my head, but interesting nonetheless.

Here is something I Googled that is easy to understand.

Don't you change the properties of the circuit, even if you use the same
values ?

Sometimes. One obvious case of this is loudspeaker crossover
parts. The capactors used are often electrolytic, lower tolerance, and
not all that wonderful from the standpoint of ESR. Furthermore, it is
not uncommon for electrolytics in speakers to degrade.

OTOH, If the speaker crossover was tuned to account for high ESR
capacitors, then replacing with a low ESR part could cause an change
away from the optimum that the speaker designer had in mind.

avguytx

Because that takes more time than I care to waste. I would rather spend that time listening to music and enjoying what I have than to waste it doing that. If I've already put good caps in, why bother? I mean, good God. I guess if I had nothing better to do all day than to call manufacturers and ask them off the wall questions about stuff from 20+ years ago, that would be another story.

Wait, I DO spend time calling manufacturers all day! But then again, I'm a rep for a bunch of lines! Should I mention all the people at each company I talk to? Would it make a rats a$$ bit of difference?

jakelm

ka7niq wrote: »

Here is something I Googled that is easy to understand.

Don't you change the properties of the circuit, even if you use the same
values ?

Sometimes. One obvious case of this is loudspeaker crossover
parts. The capactors used are often electrolytic, lower tolerance, and
not all that wonderful from the standpoint of ESR. Furthermore, it is
not uncommon for electrolytics in speakers to degrade.

OTOH, If the speaker crossover was tuned to account for high ESR
capacitors, then replacing with a low ESR part could cause an change
away from the optimum that the speaker designer had in mind.

Thats it...I'm pulling everything out and replacing one of my 7's with its original type and doing an A/B test.

treitz3

[I'm filling in for WilliamM2 right now.....]:rolleyes:

Proof! Proof! I demand proof that you talked to him. How are we supposed to take that as fact unless you prove, beyond a shadow of a doubt that you conversed with him and he actually said that. Were you on the same line the whole time? Were you double blind during the conversation? I want a video tape of you proving to the world that you actually had a conversation with Brad. That way, my mind will be convinced that you might actually make a difference.

[WilliamM2 off]

I don't mean to be a smart a**, but then again I do. With all of the twisting of words and quotes and whatnot, why would we all of a sudden take your word for anything you say K7?

You have lost all credibility due to your history in past posts.

ka7niq

jakelm wrote: »

I see your point.

And worse come to worse, it would sound the exact same and last another 20 years.

My father's 1977 7a's have not been touched and sound fantastic. I feel alot of times we change out caps , just to do it. For a peice of mind.

Well, here is the way I see it.
Stick with new caps of the exact same kind and values, and you are assured of getting what the designer intended.
Deviate from stock, and you are taking a chance.
It can sound better, but it can also sound worse too.
This is assuming the caps replaced are not bad.
IF the caps are bad, any cap will sound better.
But, you will always wonder if the change is due more to an aging cap being replaced with a new one.
Solution ?
Start out replacing old caps with the exact same brand and type first.
Listen for awhile, THEN make changes.

steveinaz

ka7niq wrote: »

Here is something I Googled that is easy to understand.

Don't you change the properties of the circuit, even if you use the same
values ?

Sometimes. One obvious case of this is loudspeaker crossover
parts. The capactors used are often electrolytic, lower tolerance, and
not all that wonderful from the standpoint of ESR. Furthermore, it is
not uncommon for electrolytics in speakers to degrade.

OTOH, If the speaker crossover was tuned to account for high ESR
capacitors, then replacing with a low ESR part could cause an change
away from the optimum that the speaker designer had in mind.

I'm sure there is a ton of variables going on, beyond simple part-for-part replacement.

ka7niq

treitz3 wrote: »

[I'm filling in for WilliamM2 right now.....]:rolleyes:

Proof! Proof! I demand proof that you talked to him. How are we supposed to take that as fact unless you prove, beyond a shadow of a doubt that you conversed with him and he actually said that. Were you on the same line the whole time? Were you double blind during the conversation? I want a video tape of you proving to the world that you actually had a conversation with Brad. That way, my mind will be convinced that you might actually make a difference.

[WilliamM2 off]

I don't mean to be a smart a**, but then again I do. With all of the twisting of words and quotes and whatnot, why would we all of a sudden take your word for anything you say K7?

You have lost all credibility due to your history in past posts.

Then do not read my posts, and go on about your merry way ?

jakelm

ka7niq wrote: »

Well, here is the way I see it.
Stick with new caps of the exact same kind and values, and you are assured of getting what the designer intended.
Deviate from stock, and you are taking a chance.
It can sound better, but it can also sound worse too.
This is assuming the caps replaced are not bad.
IF the caps are bad, any cap will sound better.
But, you will always wonder if the change is due more to an aging cap being replaced with a new one.
Solution ?
Start out replacing old caps with the exact same brand and type first.
Listen for awhile, THEN make changes.

The one 12uF Maylar and one 34uF eletrolytic cap is very easy to replace on my 7's xover. I will do it and see which sounds better.

Hell,,,you never know

treitz3

ka7niq wrote: »

Then do not read my posts, and go on about your merry way ?

I will not go away because some people on the forum care about the integrity, honor, respect, dignity, and intelligence of the forum.

You questioned George.........now I'm questioning you. It works both ways.

ka7niq

steveinaz wrote: »

I'm sure there is a ton of variables going on, beyond simple part-for-part replacement.

Yes, a LOT more then meets the eye.
Here is a funny example.
Granny's recipe for swiss steak calls for cheap round steak cooked a LONG time.
IF you substitute a better cut of meat, and do not adjust cooking time, you will have meat pudding :eek:
So, as we can see, simply substiituting a "better part" is not always best.
I KNOW this question is coming, so lets head it off.

"Yeah, but what about all the guys running SDA speakers with all Solen Capacitors" ?

Well, I say "what about them"

HOW many of them have actually replaced their old aging caps with stock electrolytics and mylars of the same kind first ?

HOW can they confidently say "The Solen Caps sound better"
Better then what ?

Better then aging caps, you bet.
Better then new, stock replacements ?
It is possible.

But unless a baseline is first established ..........

ka7niq

treitz3 wrote: »

I will not go away because some people on the forum care about the integrity, honor, respect, dignity, and intelligence of the forum.

You questioned George.........now I'm questioning you. It works both ways.

You are displaying none of the above

jakelm

Now where can I find a 12uF Maylar cap.

I guess i can throw my old one back in since they dont degrade as quickly as electrolytic. So the older original Maylar should still be good.

Damnit....and I thought I was done with those speakers......:mad:

danger boy

jakelm wrote: »

The one 12uF Maylar and one 34uF eletrolytic cap is very easy to replace on my 7's xover. I will do it and see which sounds better.

Hell,,,you never know

i for one would be very interested in your findings.. i redid the crossovers on a pair of 7A's, because they were blown.. so I had no reference point on sound.

now i've got all the caps and resistors ready to go on a good sounding pair of 7B's. but you brought up a good point. basically saying. if it ain't broke, don't fix it. so i am interested in your findings. I went with Mills/Solens in the 7A's, but so far they have cleaned up the highs, bass is ok, mids still seem to be a bit veiled. the 7B's. I actually prefer over the A's for soundstage, but they sound veiled too in the mids without any xover mods yet.

ka7niq

jakelm wrote: »

The one 12uF Maylar and one 34uF eletrolytic cap is very easy to replace on my 7's xover. I will do it and see which sounds better.

Hell,,,you never know

TRY and get the exact same brand and type of caps, install and listen for awhile.
THEN switch em for better caps.
Listen again.
I have had mixed results.
Trust your ears, and do not hesitate to remove the "better" caps if they do not sound better in YOUR application.

jakelm

ka7niq wrote: »

TRY and get the exact same brand and type of caps, install and listen for awhile.
THEN switch em for better caps.
Listen again.
I have had mixed results.
Trust your ears, and do not hesitate to remove the "better" caps if they do not sound better in YOUR application.

I wont need to switch..i have 2 speakers..I can do a direct a/b comparison

ka7niq

jakelm wrote: »

Now where can I find a 12uF Maylar cap.

I guess i can throw my old one back in since they dont degrade as quickly as electrolytic. So the older original Maylar should still be good.

Damnit....and I thought I was done with those speakers......:mad:

yes, Mylar caps have long life.
If not, here http://www.madisound.com/capcoil.html

jakelm

danger boy wrote: »

i for one would be very interested in your findings.. i redid the crossovers on a pair of 7A's, because they were blown.. so I had no reference point on sound.

now i've got all the caps and resistors ready to go on a good sounding pair of 7B's. but you brought up a good point. basically saying. if it ain't broke, don't fix it. so i am interested in your findings. I went with Mills/Solens in the 7A's, but so far they have cleaned up the highs, bass is ok, mids still seem to be a bit veiled. the 7B's. I actually prefer over the A's for soundstage, but they sound veiled too in the mids without any xover mods yet.

Mills and Solens are exactly what I "upgraded" (seeee...I dont know if thats the right word anymore....lol) too.

Original Maylar and an electrolytic are going in one and Solens in the other.

danger boy

for the 7B's that i have the parts for.. i went with Kimber Kaps.. instead of Solen.

from what I read online.. people seemed to really enjoy the Kimber Kaps..