Crossover upgrades and new tweeters

jimclass

So if it's Mylar, does it not lose capacitance and therefore does not need replacement?

F1nut

You replace it because film and foil caps are superior.

F1nut

Be sure replace the resistors while you're in there with Mills.

strokin

Just ordered my 4 new rdo194 tweets, yee haa! I will be on the porch like a hound waiting on the UPS truck.

RandyCroissant

Done!! The crossover upgrades are complete; including the TL mod and new RD0198 tweeters. A little change from the norm, I mounted the paired 20uf sonicaps for the sda drivers to the floor of the compartment and connected them with chassis wire. This gave me plenty of room on the board for the other caps. The depth and clarity is off the charts, and the highs are tight and clear. Awesome! My beloved Polks' are back...

voltz

Now you need some serious burn in time ...after 200 hours my 10's were a whole new beast! they well just keep getting better for awhile. ENJOY!!

michaeljhsda2

Cool. When I upgraded my 2B's they sounded great from moment I started playing them. I didn't notice any degradation in sound and then an improvement in sound (over the course of a couple of years) as others have experienced. Ymmv

jimclass

Congrats Randy. I am waiting for parts to arrive for my 2As. Hope I have similar good news

Schurkey

michaeljhsda2 wrote: »

Cool. When I upgraded my 2B's they sounded great from moment I started playing them. I didn't notice any degradation in sound and then an improvement in sound (over the course of a couple of years) as others have experienced. Ymmv

I, too, had no capacitor "burn in" issues.

My speakers were better from the first note.

TennMan

My crossover upgrade sounded great right from the start. I didn't experience any ups or downs in performance over time like some have reported.

strokin

jimclass wrote: »

Congrats Randy. I am waiting for parts to arrive for my 2As. Hope I have similar good news

which caps did you go with?

jimclass

Dayton film caps for the 20uf parts. A friend is sending me the 130s, so I'm not sure if they are Mylar or electrolytic. Soon come, mon. My setup is different than yours.

jimclass

Did you jump your polyswitch? That is what I plan to do. Still waiting for my parts...

strokin

jimclass wrote: »

Dayton film caps for the 20uf parts. A friend is sending me the 130s, so I'm not sure if they are Mylar or electrolytic. Soon come, mon. My setup is different than yours.

I have not done my crossovers yet, saving the funds. Almost have everything else completed. That's why I wondered what kind you used. and how they sound to you.

F1nut

Of course, when upgrading from the stock caps/resistors the sound will be better right away, that's a given. However, the sound will continue to improve for the first couple of hundred hours (Sonicap and Clarity) until they are fully cooked. Aspects that improve over that span are tighter bass, smoother highs and a fuller midrange. Basically, a better overall balance than at the beginning. I've heard this each and every time, so it's hard for me to understand why some of you haven't.

Furthermore, I can't say I've heard Sonicap or Clarity caps go back and forth, it's more of a steady improvement. However, I can say that Mundorf caps do go back and forth, they also take at least 300 hours to fully cook.

Schurkey

Unsurprisingly, not everyone agrees with Crites. I did not hear changes--good or bad--that I can put down to "break-in" when I replaced the caps in my 1Bs. They just sounded great, instantly, and still do.

http://www.critesspeakers.com/frequently-asked-questions.html

Q: Do components have a break-in time?

A: Some do and some don't. Capacitors would be a definite NO. Let's look at this one a bit.

You have new good quality capacitors installed in your crossovers. Capacitors have exactly two qualities that effect the sound of your music that goes through them. Those are capacitance (what we use them for) and ESR. ESR is the sum of all other qualities of a capacitor other than capacitance expressed as an Equivalent Series Resistance. ESR is a bad thing. Good caps have ESR so low it is barely measurable, on the order of a couple of hundredths of an ohm. ESR is made up of stuff like the resistance of the leads and their connections to the foil inside the capacitor or stray inductance or dielectric absorption.

So, we put our new caps in the crossovers. These new caps are right on the capacitance value the design calls for and the ESR is almost unmeasurably low. What exactly of these two qualities do you expect to change with break-in? And if either of them changed, why would you expect the sound to get better since the only way they could change is to go away from the "perfect" values they had to start with? I hope any caps you use in your crossovers are good enough that they do not change at all for many years of use.


http://www.audiokarma.org/forums/showthread.php?t=637954

F1nut

I've read the Crites stuff before and I'm convinced the guy's hearing is completely shot. He ignores the fact that different brands use different materials and different methods of construction, all of which have a large impact on the way a given cap sounds. He also ignores the fact that the material needs to form through charging and discharging, which is not all that unlike the need to bring up a long unused piece of gear on a Variac to allow the caps to form properly. In addition, the shear number of people who report the same basic results is so overwhelming that to dismiss or dispute cap burn in is foolish at best.

PolkieMan

I have experienced what F1 touts. Mine sounded somewhat better from the start but over time the the presence and clarity has increased. On the 1C the 200 hours burn was an extended time due to fact they were used infrequently compared to the 2.3 TLS everyday use.

nspindel

I have also experienced the improvements during the break in period. My experience with Sonicaps has been that the big improvement comes between 50-100 hours, and I have definitely witnessed the fluctuations in between. They progress, then regress, then improve again. After 100 hours, the improvement was more subtle and sustained (no more fluctuations), and after 200 hours they are primo.

voltz

When I first got my crossovers back from Dave I thought they sound a lot better from the start, then I started a burn in program of 12+ hours a day and after 100 I listen again and the thing that changed the most was the high's but they were new RDO-198 tweeters so maybe they were burning in too. then I listen again after 200+ etc...
To me I plainly heard improvements along they way, now I did have some fairly new analog cables that sort of got burned in also.

[Deleted User]

He completely misses dielectric absorption, also known as "capacitor memory". Charge up a capacitor then completely short it out. In a perfect world the capacitor would remain uncharged, but that doesn't happen. There will be a "ghost" of the original charge coming from the dielectric material storing the charge. In audio this effect robs transient clarity and masks detail and "pinches" the sound, especially noticeable in instruments that produce a great deal of higher frequency overtones, such as brass and stringed instruments.
If you ever find yourself internally wincing when you're listening to certain music being played on a sound system that could be the cause.

jimclass

finished my SDA2A refurbish last night. New RDO194 tweeters, new capacitors, jumped the polyswitch. Did not touch the resistors, as I assume they don't deteriorate. The speakers were in good shape before I started, so difference is subtle. Better clarity and definition in the high end. Tried the tweeters before re-capping and they sounded duller than the SL2000s, but back to quality with new caps installed. The soundstage is more expansive and seems wider than before. so far so good. only have listened briefly.

jimclass

BTW, I have not seen anything posted about adding some kind of sound dampening fiber material to the cabinets. Is that recommended? Mine are stuffed in the upper section, but the bottom has nothing. Has anyone found this to be helpful?

ZLTFUL

They should only be stuffed above the passive area of the cabinet. And the stock fiber fill is plenty.

As for not doing the resistors, why not? It is really cheap insurance. And they also make improvements of their own. Resistors are the part of the crossover that heat up and cool down. These thermal effects will cause deterioration of the resistors ability to dissipate over time.
There is also the consideration of tighter tolerances in these new resistors.

Just food for thought.

westmassguy

My 2A journey:
http://forum.polkaudio.com/discussion/143984/my-2as-finally-finished-almost/p1

The bottom of the cabinet should be completely empty. The Dacron should be no lower than the top of the PR opening, or the bottom of the lowest woofer opening.

jimclass

ZLTFUL: Interesting that you think that. I spoke with a Polk tech advisor who says it would make no difference to change the resistors. But if I was to do that, I don't see 2.7ohm 10% 5W resistors online anyway. And thanks westmassguy for the fiber fill answer. it seemed odd that the cabinets were so starkly empty.

ZLTFUL

www.soniccraft.com

Mills 12watt and Mills 10watt are both available in 2.7ohm.

And who was this "Polk tech advisor" you spoke to?
I am curious because the "standard" mods such as film caps, upgrading resistors and even the Dreadnought are all upgrades that Matthew Polk himself endorses.

The part I don't get is that while electrolytic capacitors are more prone to failure over time, it is usually resistors in circuits that are the item that fail with "the magic smoke". When they are pushed beyond their thermal limits, they cook. Plain and simple.

One quote I love to reference is from here: http://www.allaboutcircuits.com/vol_1/chpt_2/5.html
And it says, "The larger the resistor is, the more power it can safely dissipate without suffering damage."
The suggested Mills parts are significantly better at dissipating that thermal load with much lower chances of failure.

Again, it is cheap insurance ($4.40 per at Sonic Craft) that gives you pretty much new crossovers across the board (no pun intended).

F1nut

The suggested Mills parts are significantly better at dissipating that thermal load with much lower chances of failure.

And more importantly, the lower inductance of the Mills resistors.

I spoke with a Polk tech advisor who says it would make no difference to change the resistors.

Did you ask this person if they have ever modified a crossover? If they have ever used something other than a sand cast resistor?

F1nut

The speakers were in good shape before I started, so difference is subtle.

Considering the caps were 30+ years old and way past their expiration date I'm not sure why you think they were in good shape. Furthermore, if the improvement was only subtle that may be a result of using low quality Dayton caps and/or something is amiss in there.

jimclass

F1 next time you are in Denver stop by and give a listen. I'm sure you will have lots of good ideas. ZLTFL I did not see the correct Mills resistors in my search. I'll look again. I did not grill the Polk tech, but on 2 different calls to them I got the same advice. I really have no other SDAs to compare to, but these sound darned good. I bought them from a guy who had them in a box, purchased here in Denver, and they looked like they did not get much use which is amazing for a 1986 item. My other speakers are from the same era, which I purchased in Miami; Energy pro22. They were awesome but the tweeters dried out and died every few years. I gave up on paying for rebuilds as they are no longer available. At the time I purchased them it was either the Energys or the Polk SDAs, so I got em both now.