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By Jud Barber Why does a preamp costing less than half the price of other high end products have sonics judged to be as good as (some say better than) these marks? Let's look at the details of the design and build quality of the Joule Electra LA-100. There is where the secret is; but it's really no secret. All you need to do is pull the cover and start looking.
HIGH ENERGY STORAGE - The next thing you will be aware of is the large number of capacitors, over 150,000 microfarads of energy storage. They are used in the two regulated filament power supplies and two separate tube regulated B+ supplies. HIGH COST TUBE REGULATION is usually found in very expensive hardware like that mentioned above.
PREMIUM QUALITY PARTS - Further examination will reveal that all the resistors are of the expensive Holco brand. We auditioned several different brands of metal film resistors and the Holcos were head and shoulders above the rest. The prominent white caps are MITs, the best available at any cost. And cost they do; triple the cost of other high quality caps. Cardas jacks and Cardas wire are used in point to point configuration to avoid lost definition and detail in the signal. WE LISTEN - The LA-100 has a stereo/mono switch by popular demand. To prevent this feature from causing crosstalk between channels a triple pole switch is used with the center contacts grounded. Channel crosstalk is -80db. PURE DC - Now you will notice something funny. At the bottom of the signal boards there are two batteries (yes the batteries are included). They are part of the adjustable bias circuit and insure that pure DC is on the signal grids of the gain stage. Critical listening has shown this to be significant in producing the sonic signature of the LA-100. The result is clear, open treble; rich, full upper midrange; warm balanced lower midrange; and a solid deep bass presentation. Again unique to Joule Electra. MAXIMUM CHANNEL SEPARATION - The next funny (read innovative) thing you will notice is the brass shaft that connects the selector switch to the front panel. You will see this on a lot of preamps but the switch won't have multiple decks and wide spacing like the one found on the Joule. It shortens the length of the signal inputs and reduces cross talk between the channels. The multiple decks allow paralleling of the contacts which reduce the lack of transparency caused by the single contact arrangements found on most preamps, even the Joules' competition. SIMPLICITY - The second duty this switch performs is to allow all switching functions to be done with one switch. The tape monitor loop is available between each of the selector points eliminating the need for another switch. Each input is "virtual direct". SONIC EXCELLENCE - You will now note the unique shunt to ground input block, using custom made pots to our specifications. This volume/balance system is completely passive and functions outside of the signal path.The signal passes through two high quality resistors and then directly to the input tube grid. HIGH-TECH CHASSIS - Now for the icing on the cake, and you may argue that it was the first thing you noticed. The signal board is mounted on an exotic tri-flex suspension system to isolate it from the cruel world of vibrations and feedback. State of the art materials are used for this including EAR vibration bushings and ISO-DAMP sheets. Where have you seen this before? Probably nowhere! TUBES ONLY - And now the last straw--six, yes 6 tubes in a line stage only preamp. A carefully selected Sylvania 5751 for the Gain Stage and a RCA 5751 for the Mu Follower, and the 6EM7 regulator tube and 0A2 voltage reference tube, industry standards since the fifties. None of this is snake oil--all of it is what makes the )oule Electra a giant killer. Audition one in your home today. GIANT KILLER? YOU BE THE JUDGE! Thank you, ...Jud and Marianne Barber |
POWER SUPPLY ISOLATION - The
first thing you will notice is two separate construction boards. The larger one contains
the power supply, and the smaller one is the "Signal Board". The power supply
board uses broad copper traces to connect the major components, but some of the heavy
current is direct connected With separate insulated conductors.
POINT-TO-POINT WIRING - Then
you will notice that the smaller board, the "Signal Board" is unique
in that it has NO traces. That's right all the connections are point to
point with the component's lead wire being the only wire on the board. Each connection
point is a large copper pad on the board where all the leads are sealed together
with silver bearing solder. This construction technique is unique to Joule Electra.