In response to customer demand, Transcendent Sound is
proud to introduce our phono preamp to the marketplace. It is a perfect
match to our extremely popular Grounded Grid Preamp. Likewise, the
performance easily exceeds other high-end preamps at a small fraction of the
price.
Circuit Details:
Our design philosophy is to use simple, easy to build circuits, that employ
innovative features which minimize cost and achieve performance levels that
exceed the most expensive equipment on the market. This is evidenced by
the success of all of our products.
The most important parameter to optimize in a tube phono preamp
is noise. It is the most difficult to eliminate. The most critical
element in reducing noise is the first gain stage. We have achieved very
low noise performance by utilizing the 6C45pi tube.
The 6C45pi Tube:
This is a heavy duty Russian military tube that is unlike any other.
At the plate current levels used, it has more than twice the transconductance of
the commonly used 6922 tube. Also, gain is 65% higher. These two
factors combine to yield a much lower noise figure than is possible with any
other current production vacuum tube. The first stage employs cascoding
for lowest possible noise.
Passive Equalization:
The RIAA equalization is obtained with a passive network that is direct coupled
to the first stage. It has been precisely tuned to give a very accurate
playback response. No feedback is used in this design because it simply is
not required.
Second Stage:
The second stage utilizes a 12AX7 arranged in a current source loaded
configuration. It is the perfect tube for this application. The
first stage boosts the signal level high enough that it easily exceeds the noise
floor of the 12AX7. Only two stages are used because every intervening
tube in the signal path will add noise. This design uses the minimum
number of tubes in the signal path.
The
unit will operate on 115V-60 Hz as well as 230V-50Hz used in Europe and Asia.
Total Performance:
These design features produce a noise figure of at least 75 dbA. This is
outstanding for a tube phono preamp and exceeds conventional designs by at least
10 dbA if not 15. Gain is a whopping 52 dB.
Consequently, the preamp can be driven by all but very low output moving coil
cartridges. Step-up transformers can be added for these types of
cartridges. Contact us for details as moving coil cartridges require
special consideration when mated to a transformer. Connecting the Phono
Preamp to the Grounded Grid Preamp creates a combined gain of 64 dB of very low
noise amplification. By the way, the thing sounds pretty darn good.
Easy Assembly:
The circuitry is contained on two circuit boards, one for the power supply and
one for the preamp. Very little point-to-point wiring is required.
Assembly time should be less than 5 hours.
On-Line Orders Credit cards are not charged until product ships. Export Orders Export orders will have additional shipping charges that will be
manually added. Express Mail to Europe and Asia is about $60.
Contact us for amounts. Power Requirements 115V or 230V, 50-60Hz, 30 watts.
Specifications:
Signal to Noise Ratio: Greater than 75 dBA.
Gain: 52 dB.
Max Signal Out: 20 volts RMS.
Output Impedance: 1000 ohms.
Input Impedance: 47 k Ohms.
Tube Compliment: 4-6C45Pi, 2-12AX7A
Dimensions Overall: 15'W by 11'D by 4 1/4'H.
Weight: 10 pounds.