So what are the differences between our traditional DRD300B and the new TERRAPLANE 300B?

Well... for starters, we've included all of the upgrades like the Caddock Foil resistors, Riedon non-inductive wirewound resistors and more.

A newly styled hardwood base using the very beautiful Bubinga to match our new Ultrapath linestage.

The power supply has been completely redone incorporating a regulated CLFC design (capacitor-choke-fet-capacitor) for the high voltage, using HEXFRED diodes, ceramic fuses and NO ELECTROLYTIC capacitors.

Carefully designed Common Mode Chokes have been added to the 300B's DC filament supply.

A film cap is now used for the 6N1P's cathode bypass capacitor - NO ELECTROLYTICS

A carefully selected film capacitor value now bypasses the Ultrapath ASC oil cap.

All silver output transformers available as an option.
 

THE NEW DESIGN
The schematic diagram below highlights the changes in red.  Over the years I've found that electrolytic capacitors are not a friend of the SET amplifier.  I'm sure this is not news to many of you DIY'ers that have been judiciously using oil caps whenever possible.  However from a manufacturer's viewpoint, it's really hard to use oil caps everywhere primarily because they are SO BIG!  Film caps are, generally speaking, a little bit smaller but not by much.  This new regulated power supply provides the opportunity to rid the high voltage supply of these nasty components.  Say what? "But Ron, you said the the DRD power supply is not in the signal path so why is it important to to do away with the electrolytics?"  Good question but an easy one to answer.  Electrolytics are noisy, that's right they generate noise and this noise will find its way into the signal path. 

Therefore there are several benefits achieved with this new power supply design.  The first and foremost is reduced noise; there is no electrolytic capacitor generated noise and due to the voltage regulation, the ripple voltage is less than 10 millivolts, which is pretty darn good for a 550V power supply.  Low ripple voltage equals low noise and this new power supply design has reduced the noise level of the amp by an order of magnitude.  It was already about as quiet as you can get!  But that's not all.  The voltage regulation has provided a super stiff high voltage rail that doesn't sag under transient conditions and therefore the overall amplifier distortion has been reduced and the dynamics improved.  The quieter operation obtained from the HEXFRED diodes and ceramic fuses are just icing on the cake for this power supply.

I also wanted to rid the 6N1P cathode circuit of the electrolytic capacitor if at all possible.  I played around with different types of capacitors, diode, LED and battery biasing schemes but kept coming back to the capacitor and finally settled upon a Solen film cap for this part of the circuit.  It's a big cap, but there's room inside the amp for it and I think the Solen sounds the best here.

Not being able to remove the electrolytic capacitors from the 300B's filament supply without increasing the noise level leaves one looking for other solutions.  We are already using Schottky diodes and a CLC power supply in our DRD design which was a phenomenal improvement over the typical CRC supply and even supplies utilizing current source regulators.  However I felt the filament supply was still a source, or path, for noise to enter the audio signal.  So I decided to add an additional stage of filtering and one in the form of a Common Mode Choke.  Through extensive testing I'm now certain this additional choke is effectively filtering the remaining vestiges of electrolytic noise, diode switching noise and rf noise.
 

THE SONIC IMPROVEMENT
So what does all of this new stuff do?  Well, it really takes these amps to the next level of resolution.  I honestly don't see how they could get any better.  As I mentioned before, the noise floor has been lowered and the distortion is lower both of which result in an amplifier that retrieves more of the low level information.  You may hear things on your discs that you've never heard before.  This TERRAPLANE really fleshes out the nuances and subtle harmonics while at the same time improving the dimensionality (more of that 3D SET magic).  The details are crisp and clean without any unnatural artifacts and the dynamics are as good as they get from 7 watts of power.

Please note; the above mentioned sonic improvements can only be fully realized with this "package" of improvements as a whole, i.e. the individual design changes implemented here only offer very subtle differences on their own.

No doubt, many of you current DRD amp owners will want to implement some of these changes if not all of them.  If there is enough interest I may offer an upgrade package, however the changes are extensive requiring disassembly of the amp, drilling new mounting holes in the chassis, rewiring, etc.  It might be easier to sell your DRDs and spring for the new TERRAPLANE!

Pricing for the new TERRAPLANE 300B

THE COMBO DEAL
We've taken some criticism over the years for not offering a linestage that cosmetically matched our amplifiers.  Well, now we've finally done it!  Matching Bubinga hardwood chassis for both our TERRAPLANE 300B amps and ULTRAPATH Linestage.  So buy them both now and we'll sweeten the deal with a really great combo offer.  Purchase a set of TERRAPLANE 300B amps and one of our ULTRAPATH linestages and we'll knock 10% off the total price.  You save $425 on an assembled set and $325 on the kits!

Good luck finding an amp/linestage combination of this quality, beauty and craftsmanship for less than 10 grand at your local brick and mortar high end store.  And of the course, if you build it yourself, the kit price for this combo is just plain stupid.... stupidly low!

For you vinyl freaks, a matching phono stage is in the works and will be available very soon too!
 

DRD 300B

DRD 45

TERRAPLANE 300B

45 STAR CHIEF

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