My Headphone System

Saturday, September 1, 2012

Introduction

I love headphones. I can listen to loud music any time of day or night without disturbing the neighbors, while sitting on my favorite chair or lying on my bed snug in the covers.

Compared to speakers, I get far more resolution for the cost.

I have a personality flaw (or advantage?)---I am often not content with what I have, and I'm driven to upgrade. When I find a good audio company or designer who makes stuff I really love, it means that their taste matches my taste. Audio is subjective, so there is no absolute truth. There is only the lovely discovery of finding that I share a way of perceiving music with someone who is good at making audio equipment.

Some companies I've been fanatical about in the past are Naim (British company) and Donald North Audio (an American manufacturer of speakers and headphone amps).

More recently, I discovered Igor Kuznetsoff (company name: K Works Audio), a guy who does custom modifications, and his taste seems to agree with mine precisely. Custom modifications are always a risk. It's not like purchasing items from an internet retailer (like Headroom) with a money-back guarantee. I had to take some leaps of faith, but I am pleased with the result.

Here are descriptions and photos of items in my headphone system.

Tuesday, August 28, 2012

Audeze LCD2 headphones

My main headphone is the Audeze LCD2 (revision 2). This is a planar magnetic design, which has extremely fast transients reminiscent of electrostatics, but is more efficient and can be used with a regular amplifier. The bass on these headphones is killer. They are flat down to something like 10 Hz, thanks to an enormous transducer. I had Igor re-cable these. One benefit of the re-cable was that imaging (headstage) went from somewhat flat to holographic and three-dimensional. Resolution and dynamics improved.

The new cable is oxygen-free-copper, Litz wire, cryogenically treated. (I don't favor silver wire.) There is a sophisticated teflon dialectric and weave pattern. The yellow outer cover is Kevlar (how about that? a bullet-proof cable, ha ha) which has low "microphony" (that means if you rub the cable, it won't make a lot of vibration and sound in your ears) and also helps control the complicated internal weave.

The TRS plugs are from Furutech. Igor made one modification. Their ground tab is actually magnetic steel, if you can believe that! (Bad for sound, and surprising to find in a boutique part.) Igor dremeled out a channel to hook up the ground directly to the gold-plated copper.

The grilles are a bit resonant, so Igor added damping material.

Finished headphone. There is a pressure-relieving clear plastic strip across the top. I found the headphone to be uncomfortable, applying too much pressure to my jaw. Igor added this pressure-relieving strip. The headband remains adjustable and still applies enough pressure to stay on my head.

SuperBerry DAC

Igor makes a DAC-- called the "SuperBerry"-- well, actually he modifies one. It starts life as an inexpensive Beresford unit (around $120 to $300 depending on what version you get) but quite functional -- has 4 switchable inputs and is available with a 96K chipset or 192K Wolfson chipset. Igor replaces all the key components, pretty much using only the digital chips and D/A. This is the most analog-like DAC I've heard. Before this I thought the Audio Note DACs were pretty good, but this beats Audio Note with its resolution and dynamics. With the Audio Note DACs, I liked the "sweet highs." The SuperBerry, on the other hand, has resolution that conveys musical expression more powerfully--ultimately it's not sweet highs I want, but resolution I want. If the music is sweet, then this DAC can be sweet too. The down side? It can be revealing on bad sources, but on the whole I feel the resolution and dynamics convey so much music that I like it, no matter what recording quality.

I power the SuperBerry from a sealed-lead acid battery. Batteries can provide very clean power, but they need some capacitance in parallel with the output to deliver fast transient power. The SLA battery is part of a Belkin battery backup unit. This photo of the back compartment (here, open) shows the capacitors. You can also see that the battery is covered with foil to shield it.

Sealed lead-acid battery that powers the SuperBerrry.

Digital interconnect

I use the Clearheart Digital IC. One of the noticeable improvements over other digital ICs I've tried is the extension in the highs. Digital has more resolution in the highs than I thought! And of course, the important test is always, "Does the increased resolution provide more music?" It does. Apparently the timing of those bit transitions is very critical. This has a complex internal construction that, among other things, suppresses standing waves.

Clearheart Digital IC

Analog interconnects

I use Igor's "Clearheart" interconnect, terminated by RCAs on both sides. These interconnects are strong in their lack of dynamic compression. Consider a powerful swell of dynamics produced by a trombone quartet. A Cardas Neutral Reference IC, another IC I've heard, is good but still feels like the dynamics are pushing up against a wall. With the Clearheart it feels like there is nothing in the way of the most powerful dynamic swells.

The Clearheart IC is quite flexible, which helps to prevent vibration from getting into the component (or affecting the cable itself).

It's terminated by the Eichmann "Bullet" RCAs. These are interesting: they have a very small area that contacts the outer ground of the female RCA.

This cable does not have a normal shield, but uses ERS paper instead to protect it from RF. My understanding is that shields tend to compress dynamics, so the lack of a metal shield may be a critical reason the dynamics are so good. The cable uses oxygen-free copper Litz wire, with some kind of elaborate arrangement of teflon and air dielectrics.

K Works Clearheart IC

Power Cords

Igor makes a power cord called the Empowered Power Cord. Unlike the faddish thick "fire hoses," it's flexible and won't bridge vibration into the component. (If you have gone to the trouble of isolating the component mechanically, you don't want to use a stiff power cord and bridge ambient vibration back into it.) I've only done a few experiments to check how it compares to other cords.

On my headphone amps, using the Empowered Cord gets me much better bass -- much deeper, more powerful -- compared to a Cardas Golden Reference cord.
On my CD transport, it gets me better extension and resolution in the highs compared to a Cardas Golden Reference.

The Empowered Cord (version 2).

Modified Woo Audio headphone amp

Igor did a custom modification of the Woo Audio WA6-SE headphone amp. This is a very powerful SET (single-ended triode) amp which both screams power and has great delicacy. One of the most noticeable things about the mod is the instantaneous power delivery -- transients have power. For instance, something as simple as a guitar pluck has a powerful snap to it, the kind of energy you hear in live music.

Shot of the WA6-SE amp provided by Woo Audio.

One of the changes was replacing the wiring. Here is a shot of the before/after wire (the thicker wire at the bottom with teflon dielectic is the new wire).

Wire inside the Woo: before (upper) and after.

Early stages of rewiring the signals that connect to the volume pot, the tubes, and the otputs (there are two outputs in the Woo, one for low impedance 'phones and the other for high impedance).


Note the caps that physically are close to the signal tubes and provide instantaneous power for big transients.This helps the dynamics (macro- and micro-dynamics) and this kind of circuit modification is a signature of Igor's.

The Woo has two inputs that are switch selectable; this photo shows where they enter the amp. Igor used good Litz wire even for wires this short. Every little bit helps--if you make a bunch of small improvements, you end up with a large improvement.

Vibration isolation

We live with ever-present vibration: from motorized equipment (washing machines, vehicles) or from natural ground-borne vibration that is present even in tectonically quiet areas. Electronics are sensitive to even small vibrations.

There seem to be two largely opposite philosophies to dealing with vibration. One is to support the equipment on rigid cones or spikes (a la Black Diamond Racing); and the other is to provide something springy that makes a natural low-pass filter (filtering out most frequencies above the resonance of the "spring-mass system"). I always found more benefit in springy/compliant damping.

The K Works Audio "Pneufeet" are the compliant type, made from squash balls, plastic cups, and damping compound.

I also use a combination of four Pneufeet in one package, for supporting heavier components:

Sunday, August 26, 2012

Power conditioning

I use two types of K Works power conditioning.

The "Power Station" -- a power conditioner at the system
"Peripheral Silencers" -- several boxes plugged into other circuits of the house

Power Station

Igor makes a power conditioner based on the use of

Shunt capacitors. The five outlet pairs are isolated and have 10 microfarads of shunt capacitance (AC-rated Polypropylenes) between hot and neutral each, and smaller caps from hot and neutral to ground.
Ferrites.
RF-absorbing carbon-fiber fabric ("ERS paper").

It's a relatively simple design compared to the complex power regenerators made by PS Audio. He builds the parts into a large off-the-shelf power strip. (One advantage to having a power conditioner that looks like a power strip? I don't have to worry at a headphone meet that someone will think it looks valuable and "walk off with it.") I haven't used other power conditioners so I can't make a direct comparison, but I can say that it has a very large effect especially noticeable in the upper-end extension and resolution. The increased resolution has a musical effect -- it doesn't lead to thinking about the music, but rather to feeling more of the music. For me, this is always the most important test.

In this photo you can see that a surge protector is present. The power cord is the same design as Igor's "Empowered" series, and a large ferrite (inside the black cover) is visible at the far end from the plug.

An advantage of this simple design---it doesn't put many components in series with the power, meaning it won't limit the current during large instantaneous transients.

Peripheral Silencers

The Peripheral Silencers are boxes containing shunt capacitors and ERS paper that you can plug into other circuits of your house. You don't want to plug these into the same circuit as your system, because they contain a large capacitor shunting neutral to ground, and that may cause hum. But in other circuits of the house, these quiet down the power lines and reduce the noise floor of the system. You can also get a "System Silencer" to put on your stereo's circuit, but I didn't need that because I have the Power Station.

Peripheral Silencer

Friday, August 24, 2012

PS Audio Lambda II transport

I use a PS Audio Lambda II CD transport. (Yes, I'm still using Redbook CDs -- no computer audio here.) I purchased this as a used item in 2010. It's pretty good in its stock form. But after the K Works Audio mod I was getting world-class results from Redbook CD, seeming to exceed even high-resolution computer playback.

It's very analog-like. I prefer analog, actually, but I don't have space for a turntable, and I find most of the music I like on CD.

One of the analog-like things about this is the dynamics, micro- and macro-. Small dynamic changes are filled with musical expression, and large dynamic changes happen with ease.

The highs have extension and resolution that is hard to believe from Redbook CD. Just astonishing.

Upgraded cable linking the main board to the WBT RCA digital out.

Sorbothane washers, used to mount the power and main boards and provide some vibration isolation.

Capacitor upgrades to the power board.

Another view of the power board.

View of the power board showing how it is supported in the middle by compliant material.

So that the IEC inlet would not bridge vibration from the chassis onto the power board, Igor routed out some clearance.

The IEC inlet is also mounted with compliant material (probably sorbothane).

Main board. You can see the complex way ERS fabric was mounted to the top of the digital chips, which reduces jitter. The ERS paper must be installed correctly to increase its effectiveness and prevent static buildup that would be dangerous to the chips.

There are small Polystyrene bypasses on the underside of the main board that help to clean up the power.

Damping compound added to the CD reader assembly. There is a lot of that material on the underside, also.

Thursday, August 23, 2012

Hifiman EF5 mod

The Hifiman EF5 is a hybrid headphone amp (12AU7 input stage and solid-state output stage) designed by Hifiman to drive their inefficient orhtodynamic headphones with some heft. I am using it with a different orthodynamic, the Audeze LCD2.2.

I was a bit antsy about using the EF5 -- I'm a "tube guy" -- I have only used pure tube amps before, not a hybrid. I used to think solid-state could never approach the musicality of tubes (especially a solid-state circuit with two opamps like the EF5). But I am very happy to report that I am wrong---it's great.

Igor had already done an EF5 for another customer and could tell me that it was a good amp for the price ($400). It had some expensive parts in it and was a great stock base for a mod.

I listened to the stock EF5 and I was impressed with transient handling. Leading edges seemed very clean and transients could pop right through a complex mix. However, it was a bit of a "raucous" amp, with things getting too rowdy in loud passages, and there wasn't as much musicality as one could desire.

Igor did things like upgrade the opamps, upgrade the capacitors, add some RFI-absorbing ERS paper, upgrade the power umbilical, etc.

I discovered an amazing NOS brand of 12AU7-- the French Radiotechnique.

The result is a gorgeous-sounding amp. Great dynamics and musicality.

Photos of the interior: