Benchmark's DAC-1 is one of those rare examples of a professional unit which has found favour amongst audiophiles. It's a lot better than the internal DAC in many common CD players and often a more cost-effective upgrade than buying a new player of comparable quality.

Compared to some high-end Hi-Fi DACs however, it's 'not bad' but tends to smear fine detail and lacks air.

The signal path contains ICs which look impressive on paper but are considered obsolete for modern Hi-Fi. We replace these with state-of-the-art devices, such as used in the most expensive players.

Additional mods to the circuit topology streamline the signal path and elevate this little DAC onto a level where it will comprehensively outperform all but the most exotic audiophile players.

"I have to say, after two weeks, the DAC is sounding incredible, testing my REL subwoofers to their limit - I might have to upgrade them next. The sound is a large contrast from what I previously had."
        Robert McAdam, Auckland, N.Z.

"I have played CD after CD and it has truly increased musical enjoyment - the sound is cleaner, huge realistic dynamic range, more detailed than I ever heard with the original. The bass is very, very fast with accurate response and sounds wonderful. The midrange is stunning - fantastic wide and deep soundstage. It's a killer!"
        Andy Thai Lam, Noble Park, Vic.

Good sound relies not just on good cables, but also on good connections.

This superb hand-made valve preamp is quite old but still sounds fine.  The problem is the sockets are just not up to scratch and preventing this unit from reaching its full potential.

The old RCAs have oxidised badly and become unreliable. The fact they have bakelite insulators gives a clue to how old they might be.

The thread on the one at the right of the bottom has stripped and it's come adrift. Looks kinda sad, huh?

One of my absolute favorite pieces of 'Audio Jewelry' is the WBT-0201 E.

Beautifully machined in oxygen-free copper alloy and heavily plated with 24 carat gold.

This has got to be the RCA connector of choice for anyone who's serious about upgrading any high-end audio component.

Here's the thing about the WBTs...
They're fatter than most (which is one of the things I really like about them), which means the existing holes will have to be bored out.  Clearances have to be checked to ensure there's enough room inside and out before proceeding.

This preamp is to be used in a biamp configuration with 4 valve monoblocks so the outputs which were originally labelled 'TAPE' are internally wired as main outputs as well.

The primary source in this system is CD, (via a valve hybrid DAC) so the 'AUX-1' input gets the WBTs as well.

The rest of the inputs are low priority so they're are given a quick facelift with some no-name brand gold RCAs.

Well, it would be a shame to surround those gorgeous WBTs with scruffy old RCA sockets, don't you think? It just wouldn't look right at all!

Interconnects keep getting better -- and as you upgrade your interconnects, you have to wonder if the sockets you're plugging them into aren't the weakest link.

High-end interconnects are usually heavy which means that socket breakage can become an issue as well. Socket replacement / upgrade has therefore become something we do on a routine basis and there are several different grades of connectors we can use.

The WBTs above are the premium choice. They don't just look and sound good, they feel good too because they are precision engineered and very, very solid. You just won't break these ones.

To find out if your unit can be fitted with WBTs, call to arrange an appointment for an obligation-free assessment and quote!

The venerable Audio Research D-40.

This is a surprisingly good sounding little valve amp, shown here minus valve-box and on test after a connector upgrade.

Like a lot of classic amps, it's a basically good design but the way it connects to the rest of the system is downright agricultural by today's standards.

The owner wants to use this amp with his new speakers and cables...  but at the rear of the chassis is the classic yucky terminal block with graunched screws and broken barriers.

There's not much room to work with here, so it is decided to mount the new binding posts onto the little ledge behind the valve-box.

"I'm not going anywhere near that with the drill" he said.

The PCB has to be removed to allow the metal cutting work to proceed safely.

The PCB is dropped through the bottom of the chassis and wrapped in plastic to protect it from swarf and filings.

This way, most of the internal wiring does not have to be disconnected and the board is well out of the way

The connectors to be fitted are quite large so it is necessary to remove quite a lot of metal.

The chassis is securely clamped in preparation for marking and drilling and the circuit board hangs down between two pieces of particle board.

These massive binding posts will take either a 4mm cable or a banana plug.  They are 24mm in diameter so they sit snugly on the 25mm ledge behind the valve-box with a millimetre to spare.   In this position, they're nicely protected and don't increase the effective depth of the chassis.

These posts are a Taiwanese knock-off of a WBT Midline connector and are quite OK for the price.  They also use exactly the same size mounting hole as the WBT originals which leaves open the option of an easy upgrade to 'the real thing' at some later stage.

The old worn-out RCA sockets got swapped for some goldies while we were at it.

Uh-Oh.  Brittle, oxidised cable ends, broken off because of the mechanical stain of loudspeaker binding posts.

Gnarly!

Actually, these Cinemaquest Granites are very fine cables - it's just the ands that are a problem.

Things weren't looking too good up at the amp-end either.  These puny copper alloy spades just aren't up to the job, mechanically or sound-wise.

They really can't support the weight of such a heavy cable and they're too easily deformed when the amp's binding-posts are tightened.

Now, let's talk about doing things right.

These 8mm WBT 'Sandwich Spades' feature a pure oxygen-free copper contact surface reinforced with a steel thrust-plate to take the load.

Sonically and mechanically, these offer a very satisfactory solution - as an added bonus, they look pretty sexy too!

Re-terminated, reinforced with silver solder and padded out to reduce stress on the conductors, the amp-end of these cables now looks like its up to the job.

The cables have individual conductors that have to be split into two bundles and this is neatly covered with heat-shrink sleeving.  A red band is added to identify the Right channel.

At the speaker ends, the cables are again reinforced, both electrically and mechanically and fitted with high quality banana plugs.

These WBTs have a locking system that ensures that they will stay plugged in.

Cinemaquest is a 'spread-spectrum' cable, using different wires for the bass and treble, the speaker ends are fitted with blue bands to identify the treble connections.

The finished product.

One pair of Cinemaquest Granites ready to go back to their proud owner.  Apart from the obvious issue of reliability, these cables immediately sounded better when re-installed.

Using high-class wires in a high-class system is fair enough - but if they're not making the best possible contact, they simply won't deliver the goods.

Similar story...

BI-wire cables made from four runs of Audioquest CV4 twisted in parallel.

Obviously, this guy's looking to deliver current to some seriously low-impedance speakers.  Gnarly ends will only frustrate this goal due to poor contact.

After the ends are treated and dressed, they're fitted with WBT-0600's which are the best self-locking 4mm plugs we've seen.  They're also the most widely copied -- we've seen a lot of knock-offs, but when you look closely, these individually serial-numbered, German engineered plugs just ooze quality.

At the amp-end, the 6mm version of the Sandwich Spades (shown above) are fitted to ensure optimum contact.

In this case, eight spades are required to suit the owner's Quad-Mono Bi-Amp configuration.

By reducing contact resistance and providing stable, reliable connections, significant performance benefits were noted in both of the above cases.  Further, the possibility of amplifier or speaker damage due to bad connections is virtually eliminated.

If you have some quality cables that are failing to deliver because of poor contact, talk to us about having them upgraded.  We supply and fit genuine WBT connectors as the premium choice - but we can fit other brands and 'economy' types if required.

The popular ARC SP-9 MK.I Preamp, ready for a major upgrade. Redundant controls will also be bypassed to shorten the signal path.

The original RCA sockets which were bolted directly into the aluminium panel were badly worn and oxidised.

Fortunately, they're fairly easy to remove.

The holes in the rear panel had to be enlarged slightly to accommodate the new RCAs with their insulating washers.

The back panel starts to look like new with all the shiny gold plating.

Three critical coupling stages (phono stage output, line input and line output) are fitted with Jupiter Condensers (lower RHS). The original Rel-caps are retained (for 'bulk C') and the Jupiters add sweetness and fine detail.

The line input couplers are very large and are fitted beneath the board after removal of the original Wonder Caps

Result: A good little preamp made great!

While we're talking about DACs... the legendary Vimak Delta-Sigma 1800 is the largest, heaviest, most complex DAC I have ever seen. It's also one of the best-sounding Digital to Analog Converters ever made, IMHO.

Packed with electronics & constructed with a LOT of solid metal, it weighs more than most integrated amps.

The Vimak Mk.I has one fatal flaw... it's chock-full of little capacitors which will all eventually fail due to a manufacturing defect within the caps themselves.

First, the performance will drop off, then it will have trouble locking onto the data stream... if not corrected, this superb DAC will eventually be destroyed by chemical erosion. This unit had already suffered some PCB damage which in turn, damaged the delta-sigma stage.

You have to admire the sheer brute force of this beast -- the power supply sits in a shielded compartment with 2 copper-clad C-core transformers. The massive multi-layer PCB contains enough silicon to build a laptop.

This is a full-on up-sampling bitstream converter implemented in discrete logic... obviously these guys weren't prepared to wait for someone else to develop a chipset!

Result: This DAC has been fully restored and should continue to sound great for many years to come as all of the faulty caps have been replaced with highly reliable types.

The Audio Note DAC 3 is another of my favorite converters -- although it's hard to imagine how it could be any more different from the huge Vimak above.

This is a Digital/Valve hybrid which works and sounds extremely well.

This one had lost a channel which was traced to a faulty filter can feeding the valve line stage.

There is a mod for this unit which allows it to work without filters at all, however after auditioning this mod with his system, the owner clearly preferred the sound of the original configuration.

A pair of new filter cans was ordered and custom-made in the UK.

This returned the unit to original spec or perhaps just a touch better as the new cans (foreground) seem to sound a little better than the ones they replaced.

The de-emphasized output on this unit had never been used -- removing it just shortens the signal path and removes some extra switch contacts.

The original RCA jacks (PCB mounted type) are replaced with some high quality chassis mounted ones, silver wired direct to the output couplers.

Inside, you can see the tracks where the de-emphasis has been de-soldered and the silver links to the RCA jacks.

On test, the right channel seemed very quiet but the left one hummed a bit.

The hum was found to be coming from the mains cable which brushes past the tube heatsink (right of image).

An additional earth wire (black) causes the heatsink to act as a hum-shield and kills the hum very nicely.

Result: Unit repaired and sounding better than ever!

Luxman M-4000A, classic MOSFET power amp designed by de Paravincini, an amazing looking piece with its big analog meters.

This one had constant low-level buzz in one channel and had 'survived' several mods. Its owner was hoping for some improvement in sound quality as well.

If a picture is really worth a thousand words, then I don't have to say anything about the wiring!

This shot was actually taken after the unit was rewired -- the entire wiring layout has been rationalised and all of the critical signal and power conductors have been replaced with quality cable.

The Bybee quantum filters that can be seen in the middle of the chassis are in the output circuit and were previously installed by the owner.

The output circuit is now wired with Audioquest CV4+ Spread-Spectrum Hyperlitz. The input circuit is wired with Tara Labs Prism and the power wiring is replaced with 25A pure copper.

The cause of the constant buzz was found to be a combination of an internal ground-loop (cleared by rewiring) and some leaky old axial electrolytics in the voltage-gain stage's power supply. The board is modified to take some new radial caps which, as a bonus have twice the capacitance of the old ones.

The rear panel of the M-4000A consists of a tiny box wedged between massive heatsinks.

Originally, there was a subsonic filter slide-switch on the top, directly in the signal path -- then two very ordinary RCA connectors and then two female XLR type connectors for the speaker outputs (what were they thinking?).

Here (the 'after' shot), the RCA holes have been enlarged to accommodate a pair of WBT-0201 connectors and the XLRs have been replaced with Neutrik Speakons which fitted straight over the original mounting holes (with a slight twist).

Finally, the original puny figure-8 mains cable gives way to some fairly serious double-shielded 25A mains cable.

Inside the tiny box which is the rear panel, this is the view with the L.H. heatsink removed. At the top, we see the Tara Prism cable soldered to the back of the WBTs.

Below the WBTs, the Neutriks provide a 4-way connect which works just fine with the CV4 cable, creating a true bi-wire configuration inside the amp as well as out.

Below them, a custom cable clamp secures the mains input. The fuses have been moved to the Active side of the supply (as opposed to the original setup) and all of the chassis components are tied with a multi-drop ground (yellow/green).

Result: The combination of 'low-fi' wiring and a handful of dodgy mods had effectively concealed this amp's true character. After our upgrade, the transformation was nothing short of astonishing and I'd easily rate it in the top 5 amps I've had on my bench... So, don't just sit there, log on to E-Bay and bid for one... Then bring it to us for an upgrade!

The Luxman LV-105u, was a popular Valve/MOSFET hybrid integrated amp which is just so retro-cool.

This one was "No-Go" and the owner thought it might be the power tranny... and he was absolutely right!  I must admit, I wasn't too keen to repair this unit. I mean... God only knows what else might be wrong with it -- right?!

After discussing the scope of the repair with the owner, he decided to go ahead with it, on the basis that it would still be about the cheapest valve/MOS hybrid he could get - even after a big repair. He was probably right about that too!

The power transformer was absolutely shot and the Service Manual didn't tell us too much about it either.  There was no option but to conduct an autopsy. An ugly piece of business!

These old Japanese transformers are a total pain to pull down -- they're chock full of varnish which sets rock-hard and the whole disaster is brittle and fragile. There's no way to replace any bits that might break along the way either!

Once the voltages were determined, a new tranny could be built from scratch. The nearest available size of bobbin & laminations however meant the new one (left) would be quite a bit bigger.

Fortunately, the LV-105 has a massive transformer bay and, with a little bit of careful drilling, the big Aussie tranny sits comfortably with room to spare.

With grain-oriented laminations and electrostatic shielding, custom-made transformers like this are not cheap, but when you consider that it's dead silent and takes about 4 hours to reach skin-temperature, it's worth every cent.

My concern with this repair was always going to be the number of other issues that might arise after the transformer was installed. Well, the number was 3!
Dry joints, problems in the pre-heating circuit (a Luxman trademark), but worst of all, some dead output FETs - DOH!

The original FETs are very hard to get but after all of the above, I wasn't going to let a little thing like that get in the way!  The output circuit gets modified to work with modern FETs.

Conclusion: The owner decided that the valve/MOS hybrid topology made this operation worthwhile. This is a fairly large repair however and not the sort of thing I would suggest for most integrated amps.

How does it sound? Actually, pretty darn good -- the hybrid circuit makes this unit sound sweeter and more natural than most integrated amps and the bigger transformer gives it a surprising amount of 'oomph' when you turn it up. Overall, I'd say it was worth the effort.

Classé CA-400. This classic monster always reminds me of a bulldozer with its seriously butch handles. It takes two guys to lift this baby on to the repair bench -- the front panel alone weighs more than most A/V receivers!

This unit took some heavy damage as a result of a power surge.

These older Classé amps can only be dismantled by de-soldering a LOT of wires which must be painstakingly labelled to avoid errors on re-assembly.

The CA-400 has many layers and literally dozens of screws.

Final stages of re-assembly after the re-build. At this point, the individual stages have been dynamically tested on the bench and are known good. Now, they must be re-integrated with the power supply and control circuits and tested again. There is absolutely no margin for error here as that giant can in front contains about 3KW of transformer... so if anything is going to go 'bang' it will be a very, very BIG bang!

Result: Complete recovery -- "Amp-osaurus Rex" lives!

Everything about this lovely old Classé DR-6 Preamp looked excellent -- built like it would last forever... but according to its owner, it sounded 'bloody awful' and always had. When I turned it on, my wife ran into the workshop and said: "Yuck, what's that?"

No problems here -- the outboard power supply, like every other part of this preamp seems like a no-compromise device...

All of the ingredients required for an outstanding preamp seem to be here -- or are they?

Closer inspection of the main board revealed a minor defect which had clearly slipped through final inspection -- the unit had gone out missing a couple of small but vital components.

Normally, this sort of thing would have been rectified under warranty but that's long gone now. The values were then calculated and new parts fitted.

Result: It took until 2006 for this unit to reach its potential. I recommended a small run-in period, after which the owner rang to tell us he couldn't believe how good it sounds.

When it comes to upgrading a valve preamp, there are very few mods that are as cost-effective or as dramatic as Jupiter Condensers.

The use of beeswax and paper may seem technologically backward, however there's a growing trend towards the use of organics in high-end audio. Many experts now believe that plastics are not as inaudible as we used to think.

Top side of the Line Stage, with Jupiter Condensers fitted in place of Hovland's house-brand Musicaps.

Because the Jupiters are a fair bit larger than the original Musicaps, some of the condensers have been relocated under the PCB (see pic below). Classic N.O.S. (New, Old Stock) valves were also fitted.

Underneath the Line Stage PCB. These caps were just a tad too long to clear the control-shaft shown in the photo above.

The Jupiters have a distinctly hand-made look so you know straight away these are special components. Also, fact they call them condensers, not capacitors tells you these guys are doing it the old-fashioned way!

Result: Although this preamp was already a superb performer, it could occasionally sound a little sterile and a bit too 'Hi-Fi' on some material. The combination of Jupiter Condensers and selected tubes has made this unit come alive musically -- the 'Hi-Fi sound' is gone.

Believe it or not -- the fact that these condensers and our power amplifier have the same name is purely a coincidence -- cosmic stuff, eh?

The Benchmark is a great little Aussie power amp... Made in Melbourne, Yay!

It's reliable, stable and dynamic... it already sounds pretty good -- but can it sound better?

We need to flip the amp modules over to see what's going on underneath.

Closer inspection reveals that this is a well-designed circuit but it relys heavily on the the quality of the circuit board along with a few key components.

A suite of minor enhancements is then devised to take this amp to the next level of sonic performance.

Critical tracks are replaced with point-to point wiring as part to a general re-think of the amp's earthing -- this isolates small-signal ground returns from heavy power-supply and speaker currents.

Additional caps augment existing parts and the input gets a beeswax bypass.

Result: A/B comparisons against an un-modified Benchmark revealed a wider, deeper sound-stage. Instruments now have clearly defined spatial boundaries against a darker background. Spatial coherency is maintained at higher volumes than before. Overall, this amp now sounds like a much more expensive unit.