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Yellowstone Preamplifier
$25,000.00
In the process of developing the Yosemite preamplifier, further experiments were done in several areas to see just how far the new platform could be stretched. Eventually it became clear that what had been created was not simply a set of premium options but a truly separate product with a somewhat different cost and use case. Enter the Yellowstone.
While the Yosemite is the consummate purist’s choice, the Yellowstone verges on the excessive. New in-house power transformers were designed from the ground up, using Tectronix Analog Oscilloscope transformers as a model. Tectronix Analog Scopes are among the most highly executed pieces of audio equipment ever made, and their transformers contribute in large part to their special characteristics. These transformers are legendary amongst true tube aficionados for several reasons, namely that they function as built-in regulators, removing DC, maintaining very low voltage variability and achieving extremely quiet noise figures. We have additionally made them 400% overspecified for the application and added double internal shielding to them.
Far from satisfied with this change, we also added chokes to both power supplies, more than tripling the weight of the unit, and even further reducing noisefloor. We have also opted to use very expensive Jupiter Condenser copper and beeswax capacitors throughout the entire unit. The results are a vanishingly quiet line and phonostage. Fitting for such changes, every Yellowstone also ships with a selection of premium NOS tubes.
From a function standpoint, while the Yellowstone’s basic platform is retained, several key changes were made. First, the inclusion of swappable MC step transformers - these are custom made for ampsandsound and offer several choices of impedance and core material. True vinyl lovers will have essentially totally freedom to fine tune the MC input to their exact needs and desires.
A remote control was also added for those customers who desire greater convenience, and great pains were taken to select a high quality microprocessor relay latch of sufficient fidelity and quality as to match the Yellowstone. This necessitated the addition of another power supply to the preamp, so the microprocessor runs on its own separate power supply, totally isolated and separate from the audio signal path.
Whereas the Yosemite is a product that could conceivably have been built in eighty years ago, the Yellowstone allows for certain modern DNA in function, and will appeal to those who possess systems of greater complexity. Yellowstone is also intended as a permanent installation in the systems of those who need the absolute last word in detail and fidelity, with even deeper bass, and even more exquisite tonal and textural refinement.
Some of the interesting points of the pre.
The Line and the Phono are modeled/inspired by the Marantz 7.
The line and the phono each are completely separate, having their own power transformer, choke and power supplies.
The pre is completely wired via turret boards in a manner we call mission critical.
Volume control is sourced from Khozmo and is a Relay Latch system with 64 steps. The volume know is actually just an optical encoder. It too has its own dedicated power supplies.
The pre was designed to be modular, All power transformers are under their own isolated cover are to reduce EMI/RFI bleed out.
The front head unit houses the volume control and input selector… the PCB for the volume control is again isolated/shielded from the analogue aspects of the pre.
The rear tail section houses panel mount versions of the I/O.
The front and rear have internal access panels to inspect and service the volume control or I/O without tearing down the whole pre.
The nature of this pre was to give all the sonic dividends of the Marantz 7 but in a more robust/serviceable package. Though heavy, its meant to be lab grade… as such, failures should be very uncommon and fixing them straight forward.
The phono sec is a modest gain of 40 but is intended to make robust use of the SUTs. We chose to wire them via octal sockets. Each SUT is a single channel and ratio as to negate the need of a switch.
We do facilitate custom SUTs for customers to help match with their prized Carts.
Specs:
- 120V or 230v configurable.
- 2 Single Ended (RCA) line level inputs
- 1 XLR Balanced line level input
- Input impendence of Single Ended inputs is 50K
- Input impendence of XLR input is 600ohms
- MM input impedance is 47Kohms
- MC input impedance is 50ohm
- Output impedance is 2Kohm
- Line level gain is 10 - 12AU7s for gain and driver
- Phone section gain (all tube) before MC SUTS is 40 - 12AX7s for gain and 12AU7 driver
- Included SUTS are 1:9, 1:18, 1:36 and 1:24 special for SPUs.
- THD+N = 0.0110%
- THD =0.0021%
- Noise 13.04uVrms
Tube compliment for Phono:
- 12AX7 left and 12AX7 right are used for gain.
- The centered 12AT7 is the Driver
Tube compliment for Line:
- 12AU7 left and 12AU7 right are used for gain.
- The centered 12AU7 is the Driver
Balanced to Single ended conversion done with custom Cinemag input transformers.
Supplied SUTs are custom supplied by Cinemag with Altec 4722 pinout.