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Polypropylene film caps--only legend? Also, OPA2134

post #1 of 13
8/26/10 at 9:15am
Thread Starter 

I'm working on a Bugle photo preamp that calls for some .1 and .22uF polypropylene film caps and .1uF polyethylene film caps; the problem is that digikey has no polypropylene caps in this size at all! And the polyester caps they have have a 10-item minimum quantity. What could I substitute?

 

Also, I can get whatever TI op-amps I want for  free. Would there be a better option than the spec'd OPA2134?

 

 

220uF 16V el
0.1uF 50V pe
0.01uF 50V pp
0.22uF 50V pp
OPA2134

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post #2 of 13
8/26/10 at 10:55am
Thread Starter 

I just looked at Mouser and they have some polypropylene film capacitors, but not Panasonic ones...only Kemet. Do you think the Kemet ones are just as good? Did Panasonic get out of the market altogether? I noticed the Kemet ones have a 5% tolerance compared to the Panasonic 1% tolerance.


Edited by trains are bad - 8/26/10 at 10:58am
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post #3 of 13
8/26/10 at 11:48am
Quote:
Originally Posted by trains are bad View Post

I just looked at Mouser and they have some polypropylene film capacitors, but not Panasonic ones...only Kemet. Do you think the Kemet ones are just as good? Did Panasonic get out of the market altogether? I noticed the Kemet ones have a 5% tolerance compared to the Panasonic 1% tolerance.


DigiKey did drop the Panasonic film capacitor line.  That's unfortunate, but the Wima's at Mouser are much better - plenty in the MKP line, which are among the best.  Mouser also has Vishay-Roederstein, which are also very, very good (some say better).  Both are better than the Panasonic, IMHO.  Can't say I've heard much from the Kemet's.
 

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post #4 of 13
8/26/10 at 11:55am
Thread Starter 

Odd, I searched for .22uF polypropylene and only came up with the discontinued panasonic and the Kemet. My search must be fail.

 

EDIT: My search is indeed fail. I found all kinds now, now I have to make a decision. Wima, Vishay/Orange drop...does it matter?


Edited by trains are bad - 8/26/10 at 12:07pm
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post #5 of 13
8/26/10 at 1:12pm
Quote:
Originally Posted by trains are bad View Post

Odd, I searched for .22uF polypropylene and only came up with the discontinued panasonic and the Kemet. My search must be fail.

 

EDIT: My search is indeed fail. I found all kinds now, now I have to make a decision. Wima, Vishay/Orange drop...does it matter?


I haven't built a Bugle, but know some who have.  You need to be looking at the parts list supplied by Hagerman - hopefully, he's got size and lead spacing requirements.  IMHO, you're probably better off staying with the Wima's, but you need to carefully check the size and lead spacing - otherwise, you'll be ordering something that may not fit on the Bugle PCB.
 

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post #6 of 13
8/26/10 at 1:30pm
Quote:
Originally Posted by trains are bad View Post

Odd, I searched for .22uF polypropylene and only came up with the discontinued panasonic and the Kemet. My search must be fail.

 

EDIT: My search is indeed fail. I found all kinds now, now I have to make a decision. Wima, Vishay/Orange drop...does it matter?

 

Quote:

Originally Posted by tomb View Post

 

DigiKey did drop the Panasonic film capacitor line.  That's unfortunate, but the Wima's at Mouser are much better - plenty in the MKP line, which are among the best.  Mouser also has Vishay-Roederstein, which are also very, very good (some say better).  Both are better than the Panasonic, IMHO.  Can't say I've heard much from the Kemet's.
 


IMO you already have your answer.


Edited by balderon - 8/26/10 at 1:32pm
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post #7 of 13
8/26/10 at 1:39pm

How about Vitamin Qs??? THE BEST if you can find them,IMOvitamin_q.jpg

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post #8 of 13
8/26/10 at 2:30pm

The issue with the Wima/Vishay/etc in this case is the lack of tolerance. The Panny ECQP are 2% caps and even 2% leaves rooms for improvement in RIAA filters as you'll be talking about >0.5dB error (in some places) in the resulting curve. The Vitamin Q would probably be one of the WORST caps you could choose for this very reason (they have horrible drift characteristics). 


Edited by luvdunhill - 8/26/10 at 2:32pm
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post #9 of 13
8/26/10 at 2:55pm
Thread Starter 

Well I didn't see any 2% polypropylene caps. Is there any problem with measuring the caps I actually get in the mail, then trimming them by soldering a trimmer cap in parallel to increase the capacitance so at least they are the same? I don't know how I'd go about reducing it if the caps I get are too large in value...

 

 

I have the parts list from the hagerman, but I don't have the lead spacing; I guess I'll look up the circuit board schematic, and all the datasheets for every one of the capacitors...sure wish the digikey part numbers were still available because this would be a lot easier.

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post #10 of 13
8/26/10 at 2:56pm
Quote:
Originally Posted by luvdunhill View Post

The issue with the Wima/Vishay/etc in this case is the lack of tolerance. The Panny ECQP are 2% caps and even 2% leaves rooms for improvement in RIAA filters as you'll be talking about >0.5dB error (in some places) in the resulting curve. The Vitamin Q would probably be one of the WORST caps you could choose for this very reason (they have horrible drift characteristics). 


Well gee, Marc - now that you've confirmed for him that the Panasonic's are best in this case, he started the thread because you can't get them anymore from DigiKey.  Is there another source or a different cap that you would recommend? It doesn't look there's a polypro available, period, at Mouser that's less than 5%.

 

P.S. See - I knew someone who's built phono pre-amps would see this thread eventually.
 

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post #11 of 13
8/26/10 at 3:04pm

Here ya go:

 

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=BC2062-ND

 

National has some good alternatives, but I'm not sure if they have a sample program that you can abuse... Just look at the specs and throw out a few opamps that you think might work well in that circuit and we can go from there.

 

To reduce a cap value, just put one another one in series.


Edited by luvdunhill - 8/26/10 at 3:10pm
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post #12 of 13
8/26/10 at 3:19pm

Or

 

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=P3929-ND

 

But you will have to straighten out the leads to make them fit the holes in the PCB.

 

And Digi-key did not drop them........Panasonic did.

 

http://www.panasonic.com/industrial/components/pdf/dc187.pdf

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post #13 of 13
8/27/10 at 5:56am
Thread Starter 

Weird, this online shopping is annoying. So now there's no problem at all because I found 2% panasonic polypropylene caps at Digikey:

 

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&itemSeq=90090762&uq=634184923217109811&cshift_ck=2070555186cs507964099&client_id=5042&cshift_ck=2070555186cs507964099&client_id=5042

 

 

I don't even see the difference between this:

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=PS1H103G-ND

 

And the discontinued caps I found before, which were also Panasonic ECG 2%. But I ain't complaining. For the 220uF caps, I just chose the most expensive ones I could find in that size:

 

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&itemSeq=90044630&uq=634184928343806461&cshift_ck=2070555186cs507964099&client_id=5042

 

The manual says this about opamps:

 

 

 

Quote:
The most popular substitution will be the opamps. That is why sockets are specified.
Everyone has his or her own sonic tastes and preferences. Each opamp will sound
different. The recommended Burr-Brown (www.ti.com) OPA2134PA opamps are a good
fit for this particular circuit. However, they will discharge the batteries rather quickly.

For a 10x improvement (160 hours), use the OPA2137PA. Beware, these are much
noisier devices and should not be used for high gain stages. Opamps using bipolar
transistor front-ends are not recommended because of their tendency to demodulate radio
stations and the Bugle’s non-inverting architecture. Most importantly, use DUAL
devices and make sure pin 1 is oriented towards the output jacks.

 

Since I plan on using SLA batteries, battery life shouldn't be an issue. I'm mostly concerned with having a good clean sound.


Edited by trains are bad - 8/27/10 at 6:02am
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