How Closely Do The Values Of Electrolytic Caps From The Same Lot Match?

Where we discuss new analog design ideas for Pro Audio and modern spins on vintage ones.
User avatar
mediatechnology
Posts: 4550
Joined: Sat Aug 11, 2007 2:34 pm
Location: Oak Cliff, Texas
Contact:

Re: How Closely Do The Values Of Electrolytic Caps From The Same Lot Match?

Post by mediatechnology » Fri Sep 18, 2020 10:14 pm

Annealing is a tricky process.
That's what makes some SMT resistors very low distortion and others horrible. https://proaudiodesignforum.com/forum/p ... ?f=6&t=401
https://ka-electronics.com

Plandemic Series: "Pland3mic - Indoctornation" https://proaudiodesignforum.com/content ... nation.mp4
Plandemic Series: "Plandemic - Doctors In Black" https://proaudiodesignforum.com/content/Plandemic.mp4

CDC: "For 6% of the deaths, COVID-19 was the only cause mentioned. For deaths with conditions or causes in addition to COVID-19, on average, there were 2.6 additional conditions or causes per death." https://www.cdc.gov/nchs/nvss/vsrr/covi ... /index.htm

User avatar
JR.
Posts: 3490
Joined: Sat May 24, 2008 7:21 pm
Contact:

Re: How Closely Do The Values Of Electrolytic Caps From The Same Lot Match?

Post by JR. » Sat Sep 19, 2020 8:51 am

That thread about smd resistors is pretty old and I didn't even share about my drama with operating high Z SMD resistors at high voltage, another case where larger package resistors were required to meet spec.

JR

PS: For my outlet tester I realized off scale >500M insulation resistance @ 500V (the 100M resistors in smaller SMD packages wouldn't meet the voltage spec.)
Don't only half-ass tune your drums. Visit https://circularscience.com to hear what properly "cleared" drums sound like.

montemcguire
Posts: 11
Joined: Fri Mar 30, 2018 9:26 pm
Location: Watertown, MA USA

Re: How Closely Do The Values Of Electrolytic Caps From The Same Lot Match?

Post by montemcguire » Sat Sep 19, 2020 6:24 pm

terkio wrote:
Thu Sep 17, 2020 6:53 am
I was told, resistors were sorted at the end of the production line, so the 5% I got were those that did not make it in the 2%.
So I had those from the same of the two sides between 5% and 2%.
Does this make sense ? Is it this Now days ?
I think it depends on the manufacturer. I have measured and matched a lot of Susumu RG series SMD metal films, and there seems to be no 'hole in the middle' of their value distribution. They're all well within datasheet spec, but then again, I'm at 300ºK and the spec is good over a slightly wider range. Our local AES group got the Susumu rep out to make a presentation and I was able to ask some questions to the engineer.

Their process is unique in that they print the NiCr pattern then overcoat it with a 'mineral coating' instead of epoxy. They can laser trim through that, so it ends up making a very stable part, since no mechanical stress remains from trimming. The engineer said that they basically trim each part to tolerance, but what was more interesting is that they can trim for tempco as well! Not sure how they do that, and he wasn't about to tell me, but I have no reason not to believe it So, I think it's a tradeoff of taking more time to trim to result in a higher cost and tighter tolerance part. They might do some sort of magic on the lot level to exclude or more heavily anneal the raw blanks, but it was described more as a 'trim' process rather than a 'test and sort' process.

So, I think it depends a lot on whose parts you're using. The Susumu RG parts are not cheap, but they're not a fortune either. Panasonic seems to make something fairly close in quality (ERA series) at a slightly lower price with generally a better stock of offbeat values, but the Susumus might have a little better long term stability - not sure what the overcoat is for the Panasonics, and plain epoxy can drift with water over time as the epoxy expands and contracts.

User avatar
mediatechnology
Posts: 4550
Joined: Sat Aug 11, 2007 2:34 pm
Location: Oak Cliff, Texas
Contact:

Re: How Closely Do The Values Of Electrolytic Caps From The Same Lot Match?

Post by mediatechnology » Sun Sep 20, 2020 5:30 am

This is the report that Dave Hill shared with us on SMT resistor distortion sometime ago: http://www.waynekirkwood.com/images/pdf ... nesong.pdf

It is posted in the thread here: https://proaudiodesignforum.com/forum/p ... ?f=6&t=401

Image

Earlier in the thread there are some AP measurements comparing a couple of brands of SMT to TH. (includes Susumu).

Here's a link to the Susumu catalog: https://www.susumu.co.jp/common/pdf/n_e_all.pdf
https://ka-electronics.com

Plandemic Series: "Pland3mic - Indoctornation" https://proaudiodesignforum.com/content ... nation.mp4
Plandemic Series: "Plandemic - Doctors In Black" https://proaudiodesignforum.com/content/Plandemic.mp4

CDC: "For 6% of the deaths, COVID-19 was the only cause mentioned. For deaths with conditions or causes in addition to COVID-19, on average, there were 2.6 additional conditions or causes per death." https://www.cdc.gov/nchs/nvss/vsrr/covi ... /index.htm

User avatar
JR.
Posts: 3490
Joined: Sat May 24, 2008 7:21 pm
Contact:

Re: How Closely Do The Values Of Electrolytic Caps From The Same Lot Match?

Post by JR. » Sun Sep 20, 2020 10:03 am

is it fair to assume that his resolution floor is 0.0008?

Some parts may be better?

JR
Don't only half-ass tune your drums. Visit https://circularscience.com to hear what properly "cleared" drums sound like.

User avatar
mediatechnology
Posts: 4550
Joined: Sat Aug 11, 2007 2:34 pm
Location: Oak Cliff, Texas
Contact:

Re: How Closely Do The Values Of Electrolytic Caps From The Same Lot Match?

Post by mediatechnology » Sun Sep 20, 2020 2:18 pm

I do think that might be fair to say.

Finding the better ones seems to be a good use of null testing.
https://ka-electronics.com

Plandemic Series: "Pland3mic - Indoctornation" https://proaudiodesignforum.com/content ... nation.mp4
Plandemic Series: "Plandemic - Doctors In Black" https://proaudiodesignforum.com/content/Plandemic.mp4

CDC: "For 6% of the deaths, COVID-19 was the only cause mentioned. For deaths with conditions or causes in addition to COVID-19, on average, there were 2.6 additional conditions or causes per death." https://www.cdc.gov/nchs/nvss/vsrr/covi ... /index.htm

User avatar
JR.
Posts: 3490
Joined: Sat May 24, 2008 7:21 pm
Contact:

Re: How Closely Do The Values Of Electrolytic Caps From The Same Lot Match?

Post by JR. » Mon Sep 21, 2020 8:19 am

mediatechnology wrote:
Sun Sep 20, 2020 2:18 pm
I do think that might be fair to say.

Finding the better ones seems to be a good use of null testing.
After designing the TS-1 I gained new respect for people who design test equipment, like the audio precision crew.

I would find it difficult to parse out distortion components that low (may be noise floor?).

JR
Don't only half-ass tune your drums. Visit https://circularscience.com to hear what properly "cleared" drums sound like.

terkio
Posts: 218
Joined: Thu Feb 07, 2019 4:17 am

Re: How Closely Do The Values Of Electrolytic Caps From The Same Lot Match?

Post by terkio » Wed Sep 23, 2020 5:02 am

May I ask, why you care about matching electrolytics ?
What about matching film caps ?
Typically in microphone preamplifiers for phantom power isolation.

User avatar
mediatechnology
Posts: 4550
Joined: Sat Aug 11, 2007 2:34 pm
Location: Oak Cliff, Texas
Contact:

Re: How Closely Do The Values Of Electrolytic Caps From The Same Lot Match?

Post by mediatechnology » Wed Sep 23, 2020 6:38 am

terkio wrote:
Wed Sep 23, 2020 5:02 am
May I ask, why you care about matching electrolytics ?
What about matching film caps ?
Typically in microphone preamplifiers for phantom power isolation.
I don't, at least not for mic inputs for anything I'd do.

The subject has come up over the years for design customer's balanced line-level inputs and outputs as well as low-cost or space-constrained mic preamps.
The customers weren't interested in matching parts either but the question was always "how well do they match coming out of the bag?"
The answer is pretty good for units of the same lot.

Since I was checking the value of about 48 caps before I installed them I decided to look at tolerance out of curiosity.
https://ka-electronics.com

Plandemic Series: "Pland3mic - Indoctornation" https://proaudiodesignforum.com/content ... nation.mp4
Plandemic Series: "Plandemic - Doctors In Black" https://proaudiodesignforum.com/content/Plandemic.mp4

CDC: "For 6% of the deaths, COVID-19 was the only cause mentioned. For deaths with conditions or causes in addition to COVID-19, on average, there were 2.6 additional conditions or causes per death." https://www.cdc.gov/nchs/nvss/vsrr/covi ... /index.htm

User avatar
JR.
Posts: 3490
Joined: Sat May 24, 2008 7:21 pm
Contact:

Re: How Closely Do The Values Of Electrolytic Caps From The Same Lot Match?

Post by JR. » Wed Sep 23, 2020 8:02 am

If you look at the old Transamp mic preamp application notes, they included CMRR trim pots. IIRC there were two trims a HF and a LF trim.

FWIW I never used trims or selected parts in manufacturing.

JR
Don't only half-ass tune your drums. Visit https://circularscience.com to hear what properly "cleared" drums sound like.

Post Reply