May 2011

Going the Extra Mile With Coupling Capacitors
Article By Clive Meakins

Difficulty Level

 

  For those of us blessed with the inclination to build or modify tube electronics there is great reward in voicing your electronics with coupling capacitors that suit your taste. The same can be done with solid-state but generally these amplifiers are more complex so the impact of a single capacitor is lessened. In my experience capacitors reward attempts to voice a system more than interconnects do but not everyone is inclined or sufficiently skilled to take their amplifiers apart. I use single-ended power amps, these are low component count two-stage amplifiers driven from a sophisticated yet simple DHT preamp. My findings are applicable to tube push-pull amps too but the more complex an amplifier becomes then the less obvious the change of a single capacitor or pair of capacitors will be.

From the get-go I will say that there will be no winner in the shoot-out. What is best for you depends on your taste and your system. One person may want a small amount of color (euphony) adding, others may want absolute clarity even if this could be uncomfortable to listen to at times. The ideal would seem to be a sound that is detailed, relaxing and dynamic; these characteristics are not easy to achieve in balance but with the right capacitor you can approach your audio nirvana. Let me also state that a great capacitor won't make a lousy amplifier sound good, indeed it'll probably make it sound worse as you'll hear more of what the amplifier is doing. One person's neutral can be another's sterile. Some systems can sound sterile without something adding a little color... so there's no best capacitor, the best one is the one that works for you. Another other way to look at this is that some people have a preference for catwalk models, others prefer various shapes (let's say shapely) and more importantly, personality.

I need to say a big thank you to Nick Lucas of www.hificollective.co.uk, Nick helped me out with the supply several of the capacitors I've auditioned for this review. I seem to have spent the last three months burning in capacitors, assessing and re-assessing, it is a long process as even a burned-in capacitor needs time to settle after it's just been soldered into place. All the capacitors benefited from burn-in though not by as much as is often made out. I believe that part of the burn-in process is down to our brains adjusting to the new sound. All these capacitors did however gain from a burn-in period but none were totally transformed once they'd been run for two to three hours.

Prices: I have given typical UK prices with an approximate conversion to US Dollars.

Audio Note Silver - £230 / $370 each
www.audionote.co.uk/comp/cap_paper.shtml
These Audio Note silver foil capacitors have 99.99% pure silver foil, 20 strand silver Litz leadouts and solid non-magnetic copper case. They use a Mylar film dielectric. I have a little bit of a love / hate relationship with this capacitor, mostly love. During burn-in it has a bright treble, too full of information and airiness. This calms down after a few 10's of hours. There's loads of clarity, definition and most of the time they are very even-handed. I realize I should take daily doses of music but if I don't use my system for a week or two I find there's a narrow band in the upper-mid where the sound is a little cold, it's only subtle and I confess I'm particularly sensitive harsh piano or unnatural sibilance with female vocals. After some fresh burn-in, often 10 hours or so, the sound returns to its excellent normal standard. When the sound is off I'm the wrong side of the balance between brutally revealing detail retrieval and the natural sound I crave. In other words the AN Silver can sometimes be slightly tilted towards an emphasis in the very last frequency band I want to be over-exposed, I know from other peoples' views that this is a personal sensitivity not shared by most others but I feel the need to tell all. When on-song in my amplifiers the AN Silver are very impressive with lots of resolution resulting in great soundstaging and imaging.

ClarityCap MR - £20 / $32 each
www.claritycap.co.uk
These ClarityCaps are metalized polypropylene film in an acrylic tube, encapsulated in an epoxy resin. The MRs are even handed and neutral. They are really quite close to some the most neutral and transparent performers. Ultimately they just lack that last ounce of "the vocalist or instrument is in the room" characteristic, so the last fraction of magic and intimacy isn't quite there, there's a depth of soul that the very best capacitors have a part in portraying, and this is missing. For many this will be a wonderful capacitor when neutrality and transparency are priorities. No harshness was observed. Some capacitors have character, I place the Jupiter in the character category whereas the ClarityCap is neutral it however does not have the depth of soul of the more complete and expensive capacitors. The sort of effect I'm referring to is when male vocals have that slight rasp, some capacitors let the through, other gloss over it. It's also about the music flowing in a more coherent, composed and natural way, harmonics have a big part to play here. Of course it's not just the capacitor that does this, any system is only as good as its weakest link so the whole system has to be up to delivering this last ounce of sound or the best capacitors won't show what they can do.

DiyHiFiSupply Teflon Tin Foil - £26 / $42 each
www.diyhifisupply.com/catalog/36
These capacitors are manufactured by SCR for DIYHIFISUPPLY, Teflon and Tinfoil. Many of the other capacitors auditioned have some form of characteristic I had to assess and decide whether or not their sound was acceptably well-balanced. There are some really very good sounding capacitors here but even so if I had a system with 3 or more coupling capacitors I wouldn't want to use the same brand in all positions, even very minor colorations can be sufficiently additive to become problematic. I class these Obblicato Teflon/Tinfoil as the most neutral capacitor auditioned which also offers high levels of resolution. The best capacitor is the one that suits your ears, system and room. These capacitors are a very safe bet and well priced but if you need to sprinkle some spice into the mix then select from the various alternatives. Some may find this capacitor over-smooth in that it doesn't quite sparkle in the way that some do, others will find the smoothness relief.

Note: These capacitors took the longest of all to burn-in; they became more detailed after 200 hours.

DiyHiFiSupply Obbligato Gold - $3.50 / $5.60 each
www.diyhifisupply.com/catalog/23
This is the lowest cost capacitor of the group. They are polypropylene with a non-magnetic casing. The Obbligato Gold put is a very respectable performance. Ultimately they miss out on the very finest detail and finesse but unless you put them up against more expensive capacitors on offer here you'd be perfectly content with them. Sure they miss out on harmonic detail and certain richness is AWOL, bass tended to be slightly "one note" with a nice thump to compensate, they are well balanced. I felt my analogue source ended up sounding more digital-like, the soundstage flattened and there was a hint of coolness to the sound. Many people will want to spend no more and will be very happy with these capacitors. Laws of diminishing returns certainly come into play, don't underestimate these capacitors, in many systems they could as good as you need they can make a good starting point before you go crazy with the credit card.

Duelund VSF Copper DC - £151 / $240 each
www.duelundaudio.com/VSF_Capacitor.asp
The Duelund VSF Copper DC use foil and high-density paper, soaked in pure mineral wax, treated with special lacquers made from natural materials and wrapped in paper. This DC version is meant for use in tube amplifiers whereas the standard version is suitable for loudspeakers. These capacitors have the lowest voltage rating in this comparison at 400V. My amplifiers power up at around 420V then drop back to 170V, this is typical tube behavior. The 400 volt rating concerned me until I contacted Duelund and was advised they stress test the capacitors at 800V so there's no need to worry.

During the burn-in phase my initial view is that the Duelund's exhibit good detail accompanied by a great acoustic around individual instruments. These capacitors do not hide or gloss over details and at the same time the sounds they make are very natural. Detailed and natural is a trick only the best capacitors can pull off. Listening to Vienna Teng / Warm Strangers on vinyl was a good test. This recording works well but any harshness is very distracting, the Duelund's were a great match.

Switching to Loreena McKennitt / The Wind that Shakes the Barley, again on vinyl, this recording was portrayed very involving intimacy. Detail was again very natural coming across as required with subtle sounds as opposed to forced sounds that say to you "you're going to hear whether you like it or not". With Keith Jarrett / The Koln Concert his piano notes were super clear, especially so when the sustain pedal was in use, with lesser capacitors the sound can be over-resonant, with the Duelunds I could hear the notes with great clarity and precision but without a clinical nature. These capacitors sound fast yet they also give notes time to develop, the reason being that they removed a layer of grunge. Bass is powerful and well balanced with the mid and treble. I could say they are clean sounding but that could suggest a clinical sound, which is not the case. Where the V-Caps have a broad sound stage, the Duelaund offer a more focused soundstage and greater depth. Exquisite sounds.

Don't confuse these flat and dark looking capacitors with the chocolates place on your hotel bed pillow. I don't know how they would taste but it would be an expensive pleasure.

Jupiter Beeswax HT - £26 / $42 each
www.jupitercondenser.com/cryo-ht-beeswax-paper-capacitors.html
The Jupiter Beeswax HT is constructed with a paper tube impregnated with phenolic resin for moisture resistance along with a resin end fill to prevent moisture ingress. There is beeswax impregnated paper dielectric, aluminum foil electrode material, pure silver leads. Compared with the Audio Note Silver, the occasional slight upper-mid emphasis is totally banished while the balance, to my ears, is on the easy side of just right. The sound is not so explicit but is meaty, focusing on the musical flow rather than the individual details. As this capacitor is not the last word in resolution though it's not shabby in this department either, the soundstage is less fleshed out than with some of the resolution-kings but that is a good trade for the shear listenability on offer, along with value for money.

Mundorf Silver/Gold/Oil - £32 / $52 each
www.hificollective.co.uk/components/mcap_supreme_silver_gold_oil.html
The MCap SUPREME Silver/Gold/Oil is oil impregnated polypropylene capacitor with a silver and gold foil. Musical flow and male vocal rasp are evident with this capacitor. There's a slight emphasis in the upper-mid to lower treble which doesn't over emphasize vocals but there's something, not brightness, just a little spotlight on some upper frequencies. Mid and treble are surprisingly close to the Duelunds and V-Cap CuTF though the Mundorf bass doesn't provide the same carpet of bass as the V-Cap CuTF, possibly this is why an area of the treble seems a touch (pleasantly) elevated.

V-Cap CuTF - £77 / $124 each
www.v-cap.com/copper-teflon-capacitors.php
Here we have copper foil with Telfon film and OCC copper leads. My immediate and lasting impressions were of dry tight bass, clear treble and very broad stage width. Bass is strong, laying a carpet of bass in the room. This was counter to my pre-conception of Teflon capacitors, taking into account some previous Teflon experiences. Treble very clear at the top-end (of my hearing), vocals are meaty. Famous Blue Raincoat / Jennifer Warnes; not only does this reference recording sound impressive, the V-Caps deliver a strong bass foundation, excellent treble extension and impressive vocals. Relative the Duelunds this capacitor produced a wider soundstage versus the Duelund deeper front to back soundscape. I would characterize the V-cap as robust sounding whereas the Duelund is more delicate. Which is better for you will likely depend on the music you mostly play and the effect you aim for.

Conclusion
To wrap this up I must say that found it remarkably easy to hear differences between the capacitors on review, what is far harder is for me to decide on my preference. To hear the quality of the best capacitors reviewed you will need a system which is very transparent. There is not a poor capacitor here. The capacitors range in price from around $6 to $370; you get what you pay for, you will surely find something to suit your pocket and your system.

You are probably asking, "What am I using?" You have to make your own very personal choice, for my power amplifiers I'm still vacillating between V-Cap CuTF, Duelund VSF DC and I am very pleased with the DIYHIFISUPPLY Teflon/Tin in my preamp. I have a soft spot for the Mundorf Silver/Gold/Oil as well.

Review System
Record Deck
Trans-Fi Salvation with Terminator T3Pro Linear Tracking arm
Garrard 301 with Origin Live Encounter mkIII

Cartridges
London Reference and London Julbilee

Phono Stages
Ray Samuels F-117 Nighthawk
Hagerman Cornet2
6072A with CCS / ECC88 with CCS, diy design

PC Audio
Dell Latitude running XP, Foobar 2000, ASIO4ALL
Beresford 7520 DAC with the "passive mod"

Preamp
DiyHiFiSupply Tram mk2 DHT

Power Amps
DiyHiFiISupply LD91 (300B SE) monoblocks with Western Electric 300B

Speakers
Bastanis Mandala Atlas Open Baffles with Chrystal drivers and 18 inch dipole basses
Visaton Topaz