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I'm a tube guy wanting to buy a few boutique capacitors for a solid state circuit. The caps will be used for coupling stages. I can easily revert to using my go-to favorites, but they tend to be rated for 450V and up, way higher than the circuit demands. It occurs to me there must be low voltage film capacitors that would work as well in this application, and maybe cost less. 100V rating or even less would be sufficient. Any recommendations? Thanks.
Follow Ups:
Modified Wima MKP-2 caps are very clear and small. I modify them by removing the stock steel leads and installing 6N copper leads and mark the cap for outside foil. 1uf 100V caps are $10 each. I have been using these for years and they have practically no sound (via straight wire bypass test). Check out this page for info:
http://tweakaudio.com/EVS-2/Modded_Wima_Caps.html
Larger Wima caps do not sound nearly as transparent.
If you can find them??
Denied facts are still facts.
I think I once took apart a Moore-Frankland preamplifier that must have been 1990s vintage. It had Electrocube coupling capacitors, but since then I have never seen this brand. By description, they appear to be very high quality.
I searched a couple years ago for Ecubes and saw that there were yellow encased and white. The white were the 'audio' types. I have yellow somewhere, no white, and the yellow are not bad. Tweaky will probably object to not bad but they are way better than electrolytics
Yes,I object!
All else is boat anchors, including the great and reasonably priced Miflex copper foil. But I regress.
Denied facts are still facts.
SS coupling circuits usually use 10uF coupling capacitors and all of you are recommending tube type low value capacitors.
sony, I respectfully beg to differ, tube gear often requires high value coupling capacitors, if you are going to be driving solid state components downstream, which, as you know, tend to have low input impedance.
Lets go with what manufactures are using. Every SS receiver or amplifier used at least 5uF and 10uF was most often used. No exceptions I saw. Tube amplifiers never used more than .3uF I ever seen over 30 years of rebuilding and most were .01 (phono stages) to .1uF.
Do you also beg to differ with all the manufactures that their engineering staffs were wrong? I await your answer.
No need to get huffy about it. To be clear, I am referring to output coupling capacitors, capacitors placed right at the output. In tube phono stages or linestages that I have taken apart, I have never seen less than 1.0uF used in that position. That's just a fact, not an opinion.
I would agree completely that between stages within a circuit, much lower values are typical.
Every schematic of all the common tube amplifiers & tube receivers such as Dynaco, Eico, Scott, Fisher, Pilot, Heathkit, Grommes, Knight, etc never seen anything close to 1uF in a phono stage. .01uF and .02uF is common.
Edits: 10/12/21
Here's a Dynaco PAS3 schematic. The output coupling capacitor value is 1.5uF, so far as I can make out. (It's difficult to read.) So I don't see how your claim holds up at least for this well known and very popular vintage Dynaco preamplifier. I am referencing C111 and C211 in this schematic, which seem to be 1.5uF/160V.
Edits: 10/12/21
is far different on the output cap, as others were. On the wayback machine you'll find preamps connected to amps with input Z of 470k so the cap doesn't have to be large.
Can someone post a schematic or name a preamplifier that actually did use an output coupling capacitor as low in value as .01 or .01uF? I'm curious.
I would argue that in the "modern" era (say 1965 to the present), no phono or linestage used such a low value of coupling capacitor, unless it was designed specifically to cut off low frequencies above some set frequency, or it was designed specifically to be mated to an upstream component with a very high input Z. I am just curious to be proven wrong, if I am wrong. And this is only a discussion; my ego is not at stake.
nt
your points about more modern design is good and since lowering the accepted output impedances (like using cathode drive for the output) to a medium or low value is the key to prevent hum pickup, which can be a real pita. Hope you didn't get me wrong.
I run my preamp to amp connection with good unbalanced cable 20 feet with absolute quiet. My house, AC wiring, and system makes it possible but I understand the frustrations of many when it comes to system integration.
Cheers to ya
your point still holds
I am talking about tube amplifiers. They do have a preamp and most use .05uF to .1uF to the power tube grids from the preamp output on SE amps or on PP amps a phase inverter tube with .05 input and .1uF out. Read any schematic. Audiokarma has a good data base.
Well, you just changed your claim from .01 to .02uF to higher values.
The Z that determines bass cut-off is the parallel sum of the input Z of the driven component and the output Z of the driver. But assuming a net Z of 470K ohms, you would want about 0.2uF, to achieve a cut-off at about 2 Hz. Yes, that's fine. But most "modern" tube amplifiers present more like a 100K ohms input Z and that is further reduced when you take into account the shunt resistance at the output of the driver. But even assuming 100K, then you need 1.0uF, for a 2 Hz cut-off. Anyway, we are comparing actual observations, and you claimed that you commonly have seen .01 to .02uF. All I am saying is THOSE values are way way lower than anything I have ever seen in working on preamplifiers and phono stages, not that my experience is vast. You mentioned Dynaco, and I dredged up the schematic of the most iconic Dyna preamplifier, the PAS3; the schematic shows an output C of 1.5uF. On my own, because you piqued my curiosity, I also looked at the Marantz 7C, another paragon. The coupler is 1.0uF. I don't doubt that there may be some much older designs, where the expectation would be for driving 470K ohms, you might see lower values, and I guess if bass cut-off was not such a big issue in those olden days, then you could use .02uF with 470K ohms, for a -3db point of 20Hz. I have never taken apart an early 1950s design. (The 7C and PAS3 are probably already late 50s/early 60s.) Anyway, I am just chatting here, trying to learn.
Really? As an output coupling capacitor value? Can you post a schematic of any of those you named?
Lew, tube amps use an output impedance matching transformer, not an output coupling capacitor.
Yes, we are talking about stand alone phono stages or full function preamplifiers, certainly not amplifiers, and I do know how tube amplifiers are generally configured. Thanks. I never dreamed we were talking about amplifiers with output coupling capacitors.
I have a First Watt F1J which uses a 1 uF cap on the input, and a SAE from 1976 which uses a 100 uF. You're right, without the actual required values, which would have been nice to have posted, we're all just guessing.
All values are below 0.1uF, and it turned out that at that level even HV capacitors are small enough to fit. My secondary goal was also to save some $$$, but using parts you already own is also a way to save $$$. (See my post below.)
Thanks to everyone who responded.
Some of your old posts have been very helpful to me, even though you may not be aware of it, so thanks!
All values below .1uF? I never seen over 30 years of rebuilding SS amps and receivers using less than 2uF in FM radio coupling sections and never below 5uF every where else.
I must be hallucinating, in that case.If it helps you to calm down, this is the solid state input PCB from a Beveridge Audio direct-drive amplifier, which has a tube-based output stage. I have posted the schematic here. I replaced C101, C103, C104, C107, C108 C109, and C110.
Edits: 10/12/21 10/12/21
C109 and C110 are 10uF @ 40 volts.
Yes, I certainly do know that. I replaced the OEM ones with ELNA Silmic II. I have also used Auricap 10uF/400V in that position with success, but I decided to stick with an electrolytic in this amplifier.
If true in this case I wish I'd known that before looking into it.
Denied facts are still facts.
...but if they're low enough, you might consider the Wima FKP, which were a favorite of the late Allen Wright of Vacuum State Electronics. They're polypropylene film & foil, and available from Mouser in lower voltages, which I'm assuming you want due to their generally smaller size. Capacitance in them is limited though.
Good luck, and thanks for an interesting topic.
All the values are below 0.1uF, and I had good ones rated for 400V to 600V at all the values I needed. At least I reduced the size of my stash, which rhymes with "trash". Thanks for the tip on the WIMAs though.
...that doesn't make sense. I know that the thickness of the dialectric determines the max voltage but any type of cap will be ok regardless of voltage rating. As you said though the size may be what your looking for so hope you find some.
btw, I tried some 100 Vdc 2 mfd Vishay caps (mylar if I remember correctly) to replace caps in a preamp output (maybe 2 volts max) and they were much better than what was in there. Just the outer appearance shows they're seriously well made. The electrocube's are also excellent if you can find any.
I really like cheap mylar Roederstein MKT (green squares) caps. Probably one of the nicest sounding caps ever produced.
Expensive teflon caps like Vh audio will have a longer break- in time than you're likely to keep the gear. Vintage PIO's are a crapshoot. Electrocubes which Lamm uses are excellent but there is no distributor.
Sure woj, and I got a nice bridge to sell you.
Denied facts are still facts.
Only in good ole' USA a family can own a bridge as it is the case of The Ambassador Bridge spanning across Detroit river to Canada. Billions in trade goes over that bridge every year so sure I'll buy the bridge from you ASAP:)
I replaced a load o VH copper caps from Audio NOte phono board (caps costed more than the whole phono stage) because the result was mediocre. I put Audio Note copper there and all fell into place. Later my friend (and owner of the phonostage) started obsessing over AN silver PIO's $$$$. I told him that his whole chain sits on copper and the sound won't balance with silver caps but he didn't listen. Another costly exercise..I bought a pair of 0.22 copper VH caps for pennies from a guy who put back $0.50 mylar caps which were originally installed in his amp. He bought the amp from a "Tweaker1500" and wanted to reverse to original voicing which was a lot more pleasing.
I read about RTX caps so much that I bought 4x0.47uF/630V to make a pair of output caps for my EAR834 Clone. After a year and half of break-in time I gave up and sourced Electrocube 950 series caps and I never looked back.
I don't even want to look inside my $12k Nagra PLP pre and it's shitload of .25$ wholesale ROE PP coupling Capacitors.
I'm not saying that designer caps are crap. It's just a guess and a bit of good luck or a lot of experience to determine what will work in what position in the circuit in what system. Nothing wrong with having a fun chasing that rabbit though. Still cheaper than a pro hooker ..
Edits: 10/08/21
Excellent retort, I must say. You certainly make a great case for those caps to be listened to since you clearly did your homework. Hard to believe though. It would revolutionary it they are readily available and your perception was shared by other aficionados.
Denied facts are still facts.
Eh, I don't know. The caps I mentioned may sound very pedestrian to you and it's OK. Audio Research extensively used multi caps in their reference line before they developed their own gold cased caps and although it's not my sound aesthetics it worked for them. VH are in business for many years now so clearly they offer a valuable service and make people happy. It takes years or decades to acquire the experience and if you have it and can make a recommendation all the power to you. I read all the negative opinions about Hovland caps which were once darlings of everybody and it didn't stop me from enjoying Hovland preamplifier which was full of them. It was a really nice unit in every regard.
The only instance you can sort of trust an online opinion on audio subject is that the person expressing it is in the same sandbox as you are.
Blessed to be the waves of audio fashion which allow us, a poor bastards to acquire out of fashion gems cheaply :)
I smiled at your comment about Hovland. I remember the ads quoting Joe Roberts of Sound Practices magizine, who highly praised them. Wow, if a SET guy likes them...
It's funny how the "darlings" come and go, isn't it? I seem to recall a similar pattern with AuriCaps, which then fell out of favor.
I tried both of them, and several others over the years, as output coupling caps in one of my tube preamps. I kept coming back to a Wima MKP 10 bypassed with a 0.1 uF MultiCap RTX (and later a 0.1 uF Soviet Teflon), the Wima/polystyrene combo having been recommended to me by a veteran builder.
I understood why many liked these other caps, but they gave me too much of an "18th row center" depth. Given I listen to Blues and Rock, the bypassed Wima sounded more upfront, which suited my music better.
I'm going to try the Soviet KBG (PIO) caps (another darling) in place of the bypassed Wima, if I can ever figure out where to fit them.
And while on the topic of general opinions, bypassing coupling caps was once nearly standard practice, then reports of "it causes smearing" began to take over. Given all this is circuit seasoning, what suits others may not be to my taste, but sorting that out can sometimes get expensive.
It's interesting what you wrote about bypassed Wima MKP10. I have a load of those Wima caps bypassing 12 PSU caps in my Audio Aero Equilibre PP amp and coupling caps are Wima bypassed by Hovlands. I also considered the "upgrade" because of so called smearing effect I'm reading on different forums all the time. Not to mention condescending (mildly speaking) opinions regarding those Wima caps. But, that French Amp was stirring the pot in US late in late 90's and it's still well regarded so I decided to just leave it alone. My Living Voice speakers are full of Hovland caps as well and I wouldn't dream of upgrading them since Kevin Scott spent years voicing that model. At the end "we like what we like" my friend said when I remarked that his 2a3 SET amp is choking on Altec 414 based speakers in big basement with his music of choice :) But he follows Joe Esmila path and what's good for Joe must be good for him as well. Myself I don't mind mylar film coupling caps in electronics, electrolytic caps in speakers and fat girls
So you have Living Voice speakers now????
I knew that you could not keep a good man down....
Retsel
There is no 'smearing' anywhere close to the audio bandwidth. people who make that claim have no knowledge of what is going on, but they will spread it all over the internet. The proper term is 'propagation delay'. To see this happening, you have to be in the high MHz range, approaching a GHz. I don't think any 'golden ears' can hear that high, nor will any piece of audio gear have the bandwidth to see it happen. Try it for yourself. Parallel a couple of caps of widely different sizes, and hook up a scope and signal generator. Use a square wave. If propagation delay is happening, you WILL see it on a scope. I don't see it even at 100MHz. I DO see it in the GHz range (but you wont see it using audiophile caps, because the lead inductance will become too high way before you get to those frequencies.)
Below is a link to a large cap "shootout", which includes his take on the Wima MKP 10. I'm mostly including that because he found them "more forward" which is also my take.
"Sound: With the WIMA MKP 10 you get a neutral, smooth and well balanced capacitor. For this price range the amount of transparency is quite reasonable and overall the MKP 10 is pleasant to listen to. Compared to the similar shaped and sized Mundorf RXF the presentation is more forward and a fraction less clear. But never the less it has good overall sound qualities. Don't forget to give it some time to burn-in. Fresh out of the box they sound restricted and dynamics are limited. After several weeks of use they should open-up.
Verdict: 8"
As your friend said, "we like what we like", and there's no universal "This is the best [cap, resistor, tube, etc] in the world, despite what some would have us believe.
One Wima I've read very few negatives about are the DC Links. I've yet to be able to try an all film cap power supply due to space limitations, but that's one I'm looking forward to hearing for myself.
"Myself I don't mind mylar film coupling caps in electronics, electrolytic caps in speakers and fat girls" A very easy to please "audiophile". This,IMO lends some cred to the fact that mylar might just not be the best cap in the whole wide world. Just sayin'.
Denied facts are still facts.
Electrocube capacitors still are made? That's a blast from the past. Yep, I know about VH Audio. I like them but was wondering about lower voltage caps that might also be smaller in size.
Well Lew, I found many cap posts by Michael Samra over on tubes asylum. He hated the RTX in his loudspeaker. He is also a big fan of some paper in oils. He would probably have lost of experience in signal path caps also. Two widely divergent opinions on the RTX??
Denied facts are still facts.
Mike always made a point about caps that operate with a DC bias across them vs those that are not biased, like loudspeaker crossover caps. I think his point is valid. RTX probably need a DC bias to sound best, but for the past 10 or more years, I have favored teflon over RTX, whereas I do like other polystyrene film caps, like RT or some that are no longer made, like Pacific Audio Supply (PAS). I actually came to believe that the "multicap" construction of the RTX might be their liability. I have some 2uF PAScaps, 200V, that are superb. Problem is they are very large and not the right value for this particular PCB.
I might point out that over many years of caps and comparisons I wasn't too enthusiastic about the tin foil poly's, check out the copper foils. Chris at VH Audio is here on the asylum front page and also makes all kinds of caps. Follow the link and shoot him an inquiry. Their quality control is top notch.
Thanks. I am very familiar with the Vcaps, both types. They definitely are superb. I guess I was hoping for something I don't already know about. The VCaps are a bit large for the intended use. I am thinking low voltage film caps will be smaller in physical size.
Story, please point a small 100v or less copper foil capacitor which is what the OP is looking for.
Denied facts are still facts.
The Relcap RT and PPT Theta are extremely well reviewed. Below are size specs on the PPT Theta. Sonic Craft say that some believe the RTX is the best sounding cap and he sells them. The Relcap RT and PPT Theta are reviewed here. http://www.laventure.net/tourist/caps.htm
If I remember correctly AA member Michael Samra is a big fan of tin foil and you might check with him if he is still around??
Denied facts are still facts.
Thanks, Tweaker. I have used all of those brands at one time or another. RTX used to be my favorite capacitor, before teflon film types became common (and expensive). By comparison, I have found I prefer teflon. REL RT are sneaky good I think. Thanks for that idea.
NagysAudio (aka woj??)
Full Member
Posts: 466
http://www.nagysaudio.com
Best Capacitor in the World! You Will Be Surprised!!! Capacitors
" on: 3 Jul 2007, 02:55 am »
I've been into audio for 11 plus years and I have heard dozens of capacitors. Everything from military specd, to audiophile grade. Ranging in price from just a few pennies to hundreds of dollars.
And the best capacitors that I have ever heard are Vishay. These are made in Germany by Vishay Roederstein to be exact, model number MKT 1822. They were previously know as the ERO capacitors. The MKT1822 is a box style timing capacitor, made out of metalized polyester. They range from 1000pF - 15.0uF and have voltages from 63vdc - 250vdc.
Most audiophiles will disagree because it goes against all audiophile grade logic. They don't have Teflon, copper foil, silver foil, polypropylene/foil design, silver leads, oil, etc. But what they have is what counts, absolutely stunning sound.
It is virtually vale free and grain free. I have never heard any other capacitor come close! They have incredible resolution and sparkle to the high frequency. The term "liquid" should have been invented for these caps. Plus they have to most un-electric midrange I have ever heard. The best part is that they are dirt cheap, a few bucks max for the larger values. And they work as well in speaker crossovers as they do as coupling or bypass capacitors in amplifiers, preamps, dacs, etc. Here's a list of some capacitors which I compared the MKT 1822's to.
AuriCap
Hovland
SCR Solen
Jensen
RelCap Audio Cap Theta
MultiCap RTX
MultiCap PPMFX
Russian Military Teflon High Voltage Types
Denied facts are still facts.
Thanks for posting that. At eighty-four cents each (at Mouser), they're certainly worth a try in an amp I'm going to be working on.
He's right that polyester (Mylar) "goes against audiophile logic", and their poor dielectric absorption characteristics can also be measured on a scope.
But interestingly enough (to me, anyway), Audio Note is using Mylar in their coupling caps. Granted, they're film and foil in oil, with silver leads, so perhaps not an "apples to apples" comparison, but for less than $2 to try Mylar, why not?
I don't want to get into an argument about how capacitors sound, but to my ears in my system, the very best most transparent capacitors are the Russian SSG (silver mica) types. The problem is their large physical size and the upper limit of the capacitance available, which seems to be 0.13uF. Highest voltage rating is 350V, I think. After that, I like the VCap teflon and tin or copper, if we're talking ultimate SQ.
I bought some of those, thinking I'd fit them in "somewhere", but will really require a scratch build with a large chassis for me to experience them.
Curiously, the 500 V rated SSG are smaller than the 350 V examples.
Why not? At that price I agree but the inferiority of mylar to polyprop and polystyrene electronically is a fact. I say if they sound great it would be a great thing for many. They only go to 250V so their use is limited. The sound of caps is all over the place along with people's perception and tastes. As always, there is no substitute for personal experience.
Denied facts are still facts.
Below is a link to the MKT1822 data sheet, which indicates that they make them rated up to 1000 VDC.
I need a couple of 0.1 uF @ 400 VDC, so that'll work for me.
Good call 1973, my bad and you are correct. They go to 1000-v. I must have misread something. Another possible good call is the Wimas that are aluminium foil caps. Some aluminium foils get excellent reviews. That is one Wima I haven't tried. The MPK10 is IMO a standard in which to compare caps. Very decent but not great. The Wima FKP just might beat it.
Denied facts are still facts.
I'm not defending the Wima MKP 10 in any big way, mostly pointing out that it's a matter of personal taste. That Humble Homemade cap shootout I linked to, for example, rated the MKP 10 an "8", while they rated the MKT1822 as a "6.5". And at the same time, the guy you quoted said the MKT1822 was the best he'd ever tried.
The only way to really know is to try them for ourselves.
You might consider tin foil-poly such as the ones below if they are small enough. Some of the tin foils get huge respect. Maybe there is a review out there on these.
Denied facts are still facts.
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