capacitors and you

[Kenneth Swauger]

Forum readers,
Here is a copy of a well written discussion on the different types of capacitors used in audio electronics. It is from an Ampex group that I'm a memeber of, but I thought you might find it interesting:

"I'm going to make a couple comments that partially fall into "good
engineering practice" but also "a certain amount of religious fervor."

It applies to all capacitors.

The Ideal Capacitor returns 100% of its charge instantly.

There is no such thing as an Ideal Capacitor.

Instead, a Real Life Capacitor has series resistance and inductance, shunt
inductance and resistance, a biased diode (for electrolytics) and a small
battery combined with the Ideal Capacitor.

One major area of concern is the dielectric. The less than perfect
dielectric is what is the biased diode and small battery represents. Not
all of the charge is returned (soakage) and the charge and discharge has
polarization with electrolytics.

The construction effects the series resistance and inductance. All rolled
capacitors will have this problem no matter what dielectric you use and no
matter what conductor you use (aluminum, gold, silver, etc.)

Stacked capacitors have much lower inductance but they tend to be
physically large except for metalized film stacked capacitors and then the
metalization may increase the series resistance.

Turns out that there are a couple of plastics that make good dielectrics:
polyethylene, polypropylene, and Teflon (TM). Mica is also a good
dielectric but it gets physically large for capacitance values useful for
audio coupling. Really good capacitors are made with a glass or ceramic
bottle and the dielectric is a vacuum. Common in broadcast transmitters
but a 1,000 pF capacitor is the size of a large mayonaise bottle for the
lower voltage ones and the size of a pony keg for the 20 kV rated ones!
Not at all practical for PCB mounting. And REALLY expensive, too.

Bad dielectrics are paper/oil and electrolytics. To be fair, paper/oil
with zero moisture is pretty good but over time it will gradually get leaky
and have soakage as it grabs water a molecule at a time.

Comparing today's electrolytics to 1980 vintage electrolytics is unfair.
High frequency losses common in electrolytics 20+ years ago is totally
unsuitable for switching power supplies. So demand for good high frequency
performance drove research to provide better electrolytics. And once
manufacturers learned how to do this the economies of scale means that they
use this technology throughout a particular capacitor design.

Soooo, in conclusion, the practice of bypassing a large elctrolytic with a
good film capacitor may not be as big an issue today as it was in 1980.

Not all of the information is published. The "better" capacitor has
essentially the same value at all frequencies, has a low Dissipation
Factor, and a low Equivalent Series Resistance. For example, check out
the chart for Panasonic "High Capacitance Multilayer Ceramic Chip
Capacitors" on page 726 of DigiKey catalog T032 (May-August 2003). Not
that I'm recommending them for audio, but this clearly shows how different
capacitors behave.

Your mileage may vary, use at own risk, children don't do this at home,
trained professionals driving the car.

Bill Ruck"
Regards, Ken Swauger

[madmax]

Great read! So if I wanted to upgrade the caps in my 1.2 crossover what would I be looking for? I have been thinking about it for awhile now.
Thanks!
madmax

[F1nut]

Hehe.....

"Mica(h) is also a good dielectric but it gets physically large for capacitance values...."

[Kenneth Swauger]

Hello,
I'm glad the information was helpful. One good source of high quality speaker parts and information is Michael Percy, in Nevada City, CA. I've been buying high quality parts from him for over twenty years and never been disappointed. He carries caps from Reliable, InfiniCap, Hovland, Solen and Black Gate; all well respected. These caps have quite a wide price range and he can help make a recommendation. His telephone number (530) 470 8650 and email address is mpercy@pacbell.net for parts listing. Keep in mind he might not be intimately familiar with Polk crossovers, but if you know the necessary values (I can help with that) he can make general recommendations. He also carries inductors, connecting wire and binding posts. I'm sure many other readers have sources and recommendations that should also be considered, but this is one source that's worked with me.
Regards, Ken

[Tour2ma]

Damn... all I thought was important was their color... :)

[har_navalta]

I've been thinking about it too max:)

[madmax]

Lets have an on-line workshop for SDA xover upgrades. KS, are you into it? Anyone else?
madmax

[organ]

That was a very interesting read. Thanks Ken:).
A few months ago I anstalled a replacement quad cap on my amp. It's shaped like a can with four caps inside. That was my first time working with caps. Actually I worked with them on my labs at school but their values were very small. The second time was replacing the bias supply caps for the amp. That was a lot of fun.

Maurice

[Ceruleance]

i'm in the color matters camp :D

Bitchin Yellow or Big Badass Blue?

[dorokusai]

I am down Max, mine are going to be sitting for a couple months so why not do some upgrading. Let me know, I will yank the guts out and hook up with you.

[Kenneth Swauger]

Hello,
Sure, I'd be happy to help with up grades to crossovers, it's an interesting part of the hobby. By the way, on a different topic, I can highly recommend the extremely well done "The SDA Compendium" written by Forum member Raife F. Smith. He has accumulated pertinent data, crossover schematics, Polk white papers, magazine articles written by Matthew Polk and photographs of SDA series speakers and combined everything in an easy to reference handbook. If you want a thorough grounding on the SDA speakers and want to find out which ones would suit your requirements, this is the way to do it, he's done a great job.
I've heard from Tyrone Thompson, an avid SDA enthusiast, who bought the book and enjoyed it thoroughly. I believe it is listed on ebay.
Regards, Ken

[har_navalta]

Originally posted by raife:
Modification Ritual for SDA SRS 1.2TL
1. Prior to upgrade, do a few hours of critical listening with well-recorded LP's and CD's. Take very detailed notes with regard to instrument placement in the soundstage, general dimensions of the soundstage, subtle musical details, and the realism of sound as compared to live performances. Make diagrams of the apparent placement of instruments and vocals within the soundstage.

2. Order Crossover Schematic from Polk Customer Service.

3. Study schematic and make a parts list of items to be replaced.

4. Take accurate measurements of crossover circuit board and measurements of stock crossover components (electrolytic capacitors, mylar capacitors, and cermet resistors).

5. Check parts vendors online catalogs for required parts. Pay particular attention to the dimensions of potential replacement parts. You want to make sure everything will fit on the circuit board.

6. Order AudioCap PPMF polypropylene capacitors (1.5uF, 12uF, 27uF values), Cardas silver quad-eutectic solder, and Cardas heavy-duty, telurium copper gold-plated binding posts from SonicCraft of Wichita Falls, TX. Cost: $293. 79. The binding post replacement requires that the holes in the binding post plate be enlarged. I used a drill bit.

7. Order Mill's MRB 1% tolerance wirewound, low inductance resistors (2.7 ohm, 7.5 ohm, 12 ohm, 15 ohm, 22.1 ohm), and 0.22uF PPMF-X metalized polypropylene film capacitors from Michael Percy Audio of Nevada City, CA. Cost: $52.93.

8. Buy two yards of 60" wide thin, silky-black knit fabric from the local Hancock Fabrics store. Stock #46794. Cost $10.44. Use this to replace the thicker stock grille cloth.

9. Go to Home Depot and buy two four-packs of 1-1/8" teflon sliders to cover the metal feet on the bottoms of the speakers. Didn't want to scratch my hardwood floors.

10. Complete all modifications for the right speaker and then do detailed listening tests comparing it to the unmodified left speaker. Listen with and without the interconnect cable in place. Take very detailed notes.

11. Complete modifications for the left speaker. Working carefully, the crossover, grille cloth, and binding post modifications took a little under three hours per speaker. This was not a trivial exercise. Care must be used to mark the positions of the components and component lead insertion points on the circuit board. Because of the larger sizes of the replacement capacitors and resistors, some components had to be mounted on the underside of the circuit board. After soldering, components were secured with plastic locking straps.

12. Do a critical post-mod listening session. Do not refer to previous pre-mod listening notes. Take very detailed notes with regard to instrument placement in the soundstage, general dimensions of the soundstage, subtle musical details, and the realism of sound as compared to live performances. Make diagrams of the apparent placement of instruments and vocals within the soundstage.

13. Mentally compare notes from the pre and post mod listening sessions. Compare the actual listening notes and soundstage diagrams from the pre and post mod listening sessions.

14. Smile from ear to ear.

Total parts cost of modifications was $364.72.

I did not replace the internal wiring because I did not notice a difference when I replaced the internal wiring of my SDA 1B's.

Improvements in sound: Not a night and day difference, after all, they sounded very good to begin with.

A. The biggest improvement was in the solidity and three-dimensionality of the soundstage. Soundstage was wider and deeper, with more of a sense of real musicians being in the room.

B. Bass was tighter and "punchier".

C. More resolution and detail throughout the entire frequency range. The resolution continued to slightly improve over a period of three weeks as the new parts were broken in. Over this period, I was constantly surprised by subtle musical details I had never heard before, particularly with my Jazz LP's.

I agree with you max, online upgrades for the x'overs in details including pictures (especially the SDA's).

Hey guys are you with us...

Har

[HBombToo]

I don't have SDA's but I am all over this 1. This is the stuff a hobby makes.

HBomb

[dorokusai]

I am in.

[Zero]

Worthy of a copy and paste job! Thanks for the info, and an excellent read!

[treitz3]

How about an old, OLD school bump.....just for Sh!tz and giggles....

My, how things change...

[jm1]

Funny this appeared right now.

Dropped off my DAC to the fellow who maintains/upgrades them and he said he has found a way around the caps (Black Gate) in the unit. Said it sounds very different and allowed him to make other meaningful refinements to hear so much more.

Going tonight to pickup his spare unit which has most of the current changes to have a listen before I commit to having mine updated.

[cnh]

IMO, we should all take a year off and get an M.S. in Engineering?

Just kidding. Hey, NO ONE is stopping the elite boys and girls from discoursing on the Erudite knowledge of SS and Tube designs and functions. Lot's of space, HERE. If anyone is at fault it's the very guys who have this knowledge and don't use this space to engage each other? The rest of us are all eyes and ears!

cnh

[Face]

Dropped off my DAC to the fellow who maintains/upgrades them and he said he has found a way around the caps (Black Gate) in the unit. Said it sounds very different and allowed him to make other meaningful refinements to hear so much more.

Probably transformer coupling. If so, it will sound more transparent.

[george daniel]

this might provide for some evening reading

http://www.laventure.net/tourist/caps.htm

[fbm211]

Strange.They didnt include ClarityCaps in thier tests...

[george daniel]

yeah,, I thought so too,apparently they did not have the budget/time for some of the caps available.Of interest to me is the bypass caps,particurlarly in power supply applications.

[fbm211]

Id like to get me a pair of those 12uf MRs for the high pass in my xovers.And maybe a px for the low and sa for the mids.Not sure if the second two would work in that application though.
And the MRs would be awsome if not so costly.

[jm1]

Probably transformer coupling. If so, it will sound more transparent.

Not sure exactly what he did, but the updates are a significant improvement! Gave the go ahead to have mine updated with the latest mods.

[Audioquest]

Thanks for that writeup

[Face]

Id like to get me a pair of those 12uf MRs for the high pass in my xovers.And maybe a px for the low and sa for the mids.Not sure if the second two would work in that application though.
And the MRs would be awsome if not so costly.

At least use ESA's if you're going to use MR's in the HF circuit.

[Tour2ma]

IMO, we should all take a year off and get an M.S. in Engineering?

Already done that... and it takes more than a year..

So is Ken S. Club Polk's patient zero for "upgraditis"?

[dcoil]

originally posted a quote from Raife about his 1.2TL upgrades. In this he refernced SonicCraft as a good place for audio caps, etc.
Har

I just wanted to add my .02. I am in the middle of upgrading my SRS's. I used Raife's 'Compendium' to organize my XO'r parts and other mods. I ordered most of the caps (Sonic Caps), resistors (Mills), quad uetectic solder, and Cardas binding posts from SonicCraft. The only thing they didn't have were the large caps I needed and were sourced from another vendor (PartsConnection). One of the owners of SonicCraft is a CP member (scdrj). I wanted to make sure I got the correct spec parts so called and got exactly what is needed for the job. SC also has a nice website - you can price all of the electronics and figure out just what it's going to cost. An added bonus is that he also gave me a nice discount (I assume as a CP member) .

I'm now done with 1 speaker and I'm currently buring it in. I'm just using a good AVR, but already I can say 'Wow - this is not an insignificant improvement!!" I'll report more later with pics and subjective analsysis of the sonic improvement when I finish the project. As I'm buried at work, it will probably be another month before I get it completed.