Okay let's talk film caps (for eq)

I did a search but wasn't finding the info I wanted.

Looking for some reccommendations for some film caps for my eq circuit. I'm changing the values for the eq in my PM1000.
The voltage is 50 volts so that rules a few of the films out, that is in the digikey catalog, as some only go down to 100V.

Anyway, as reccomended here before, I might as well put it up again in case someone can use it, but this is from a thread started by tubejay a long time ago.

To change the mid-range and high eq in the Pm1000 circuit:
1kHz to 700Hz by changing .15uf cap to .3uf
2kHz to 1.6 by changing .068 uf to .1uf
4kHz to 3.2 by changing .033 uf to .051
10kHz to 12k (to raise it up a bit) by changing .047uf to .039uf

Anyway, Wima doesn't have these exact values, some close, which I might end up trying.

there's BC MKT, as a possibility. Panasonic PPS, AVX Polyester. Epcos MKT, though again, not those exact values.

I think I'll try and keep them at 63 volts or less.

Anyway, reccomendations? It's going to be a buy a bunch and test them all out situation. I'm just trying to narrow down the choices.

I'm wary now that I bought some Panasonic stacked metal film (V series) and they made my eq pots scratchy. (replaced the originals, and no problem)

Tubejay, if you read this, I know you used MKP caps for your PM1000 eq, but I'm not sure which brand. I see there's Epcos MKP's but the lowest voltage is 160V. In digikey anyway. Hmmm.

[quote author="JW"]Anyway, Wima doesn't have these exact values...[/quote]

So parallel up a couple and get the exact value that you want that way...?

It's what I'd do...

Keith

Yeah, like this T-u-b-e T-e-c-h thingy:

Okay,

so, I havn't done this before.

To get a .051uf/50V, I just stick say, a .039/50V + a .012uf/50V together? Would I solder two legs in the same pcb hole if I can fit them?

Exactly. Perfect. That'll work. You got it.

Sorry, I was winding some quad wire last night.

what kind of brands do you guys like? I havent done any testing with film caps yet. I just tried some avx I think and they were ok. Obviously wima are good but they are really odd sized. Has anyone done any listening tests with the stuff mouser/digikey carries? Would be interested to hear about some reactions, not so much what is so awesome but more along the lines of which caps just kinda suck.

dave

[quote author="JW"]some only go down to 100V.[/quote]

That's not how caps work. You can use a 100V (or 1000V, for that matter) cap in place of a 50V one. It's a maximum, not a target.

Peace,
Al.

I'm no expert, but I've been putting Solens on the outputs of my tube gear and i like them. I have some Cornell Dubilier polyesters that (without having anything else to compare them to) sound good for the price.

I have a few Orange Drops 715P in small values that I haven't tried. Any opinions?

Peace,
Al.

Hey Dave,

honkyjonk from tapeop here. You might remember me from such threads as "Dave helps out guy who has no idea what he's doing #379"

Anyway, I have no idea what kind of films I like. For electrolytics, I guess generally, I've decided I like Nichicons a lot better than Panasonics, but I'd like to know which of the Digikey and Mouser brands suck too, so I can order the ones that don't and do some comparisons.
Unfortunately I havn't seen any Nichicon films. Have no idea if they make them. Whatever.
My console has turned into a total experiment right now. I have some ideas of what my next capacitor order is, but I'm trying to finalize it. Heh.

alk509, are you sure about what you're saying? I mean I'm pretty much a novice, so I can't say I know, but from what I've heard thus far, I thought you're not supposed to stray more than about 20% over the original voltage.

Looking again at the Mouser catalog, I realized Wima's lowest voltage rating for any film is 100V, so I don't know, if enough people say that's gonna be okay to do, I might try it, but . . . . .

where is prunedale?

I think the voltage matching with caps is more of an issue with electrolytics than film types. You can get some film caps in 50v but offten they are very tiny and wont even fit on the board if the footprint is for larger caps. Sometimes Ive had to get 400v caps to find the value I needed.

dave

the voltage rateing of a cap is the voltage at which the cap will essentialy stop functioning (blow up). compair it will running wire in a house, if you only wanted to run one 100w lamp on a line you could use a very low awg wire easily. but you could aslo use 8 gauge. the lamps would work just fine in both cases, the 8 awg is rated for more current but that doesn't mean it needs more current.

i've used 2Kv caps to couple tube stages together which are running at 200v. with no problems. all the 2kv means is that they will function at any voltage up to that perticular voltage.

dont worry about going over the voltage recomendation in a schematic. if you are working with PCB be aware that caps rated for higher voltages are often larger, physicaly but for point to point this isn't a problem.

if you know the voltage over a cap is, say, 15 volts MAX, any cap rated for over 15 volts, be it 30 or 30K will funtion just fine.

Bill

Ah film caps

I tend to like two types for not adding anything polystyrenes and polypropylenes. I tend to like stacked film construction and not wound if possable. I think most polypros sound a like if built close to the same way to my ears.

I also like to run close to the rated voltage.

Why? It seems to my ears(not I have not done blind experiments so I can't say I know this for sure or just believe it) I think it has to do with DA the thicker the film(higher the voltage rating the more area for the electrons to stay "lost" in causing the DA to be greater)

PETs can be all over the place in sound. Emperor TK has posted that there is over 900 types of PET film in another thread about capsule film. The polyemers are aranged differently by how the film is formed this could/should cause the charges in plastics in the electrostatic field of the caps to maybe act different?

With PETs(mylar) I tend to like stacked films MOST of the time. I Use PETs like some use transformer alloys to add some "warmth" I think "warmth" in caps it caused by the small time blur that DA can cause.

Pan V series are my fave for guitar and bass effects CDEs are good wimas avx etc. I find pan v are good for some microphone mods because they are close to being as clean as a polypro to my ears and they can fit in many places.

Has anyone noted the voltage ratings on some of the electros seen on Neve schematics? Voltage offsets, low voltage electros, Nice DESIGNs IMO.

Lets see what this starts

[quote author="Gus"]I tend to like two types for not adding anything polystyrenes and polypropylenes. I tend to like stacked film construction and not wound if possable. I think most polypros sound a like if built close to the same way to my ears.

I also like to run close to the rated voltage.[/quote]

The original question, though, was about caps for EQ circuits, and typically they have no DC on them.

I also like polystyrenes if they're available in the value I need, polypropylenes if the polystyrenes aren't available or are too physically big.

Peace,
Paul

Paul

Good point I was responding to one of Daves posts above about film caps likes and dislikes.

The eq stuff I don't know yet if I ever get around to building the 1081 circuits I guess I will find out. The pictures of the 1081 seem to show a mix of mylars and polystyrenes. Maybe thats part of its "sound"

Anyone with a real 1081 know what the caps are in the EQ?

Something that might be of help is I don't like polypros with guitar overdrives,fuzzes etc. to harsh for my ears with single coil guitars.

I would maybe build the EQ circuit with polypros and if the sound for a eq section is to harsh I would then try a good polyester(s).