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Red Rose was a creation by famed designer Mark Levinson.
This model is the Reference Line Level Preamp, utilizing four tubes and a separate power supply to minimize interference.
Featuring all Phillips NOS (New Old Stock) tubes, no phono stage, dual volume controls, and completely and thoroughly inspected and tested by our tube technician where it passed with flying colors.
Original MSRP was $10,000.
The below information is copied from Raptor Electronics site owned by Brian Hawkins who was an integral part of the AudioPrism - Red Rose engineering team.
All configurations were a tube line stage unit incorporating two each 6DJ8/6922 and 12AU7/5814 tubes, one each per channel, supplied by an external power supply
The preamp board is isolation mounted to the black anodized aluminum chassis with the cover dampened.
The external power supply has connectors for the preamp and AC power. It provides rectified and filtered DC voltage for both high voltage and low voltages. The external supply provides 500VDC for high voltage regulators, 11VDC for filament regulators and 11VDC for aux power.
The preamp takes the 500VDC and regulates it to 450VDC for the two 295VDC 12AU7 and two 145VDC 6DJ8 regulators. Additionally the 450VDC regulator utilizes the 11VDC for a low voltage reference regulator.
Each tube has an independent filament regulator that provides 6.15VDC in operate and 3.5VDC in Standby from the 11VDC.
The preamp has five line inputs and a switched non-buffered Tape Out. Operating modes are Standby, Mute, On and -1.5dB. The last will reduce both channels volume by 1.5dB to provide finer steps in control.
Two independent 23 position stepped ladder volume controls with discreet resistors provide attenuation with 3dB steps per position. The preamp is muted for 30 seconds after power is applied or when switched out of Standby position to either the On or -1.5dB position. Mute will defeat the output or restore immediately if the 30 second power on or Standby delay has occurred.
A front panel bi-color LED indicates red for Mute, green un-Muted. A rear panel switch allowed floating the chassis or connecting it to circuit/signal ground to obtain the lowest signal hum.
The 6DJ8 dual section triode is operated in parallel in grounded cathode mode and provides 20dB of gain. The 12AU7 White follower buffers the output without gain but provides a low impedance drive. No global feedback is utilized and the 6DJ8 is direct coupled to the 12AU7. Later Mantissa and all Red Rose Model 3 tubes were JAN/Philips 6DJ8 and 5814. These tubes were treated with a proprietary method. Tubes were selected for low microphonics, noise, distortion and 0.1dB balance between channels. The rejection rate from the selection process for the 6DJ8 was very high while the 5814 was much better. The 6DJ8 higher fallout rate was due to the stringent requirements imposed on the gain tubes for greater then 90dB Signal to Noise un-weighted and very low microphonics.
The external power supply was painted black and configurable for 100, 120 and 230 volts with transformer wiring changes. A detachable IEC power cord is utilized with the AC inlet providing a fuse within a pull-out drawer.
The supply has a 9 pin connector for the umbilical cord from the preamp to connect. The Mantissa Silver Signature Reference and the Red Rose Model 3 Silver Signature used a larger inductive capacitive supply with a 19 pin connector and larger umbilical cord from the preamp.
The Silver Signature units had upgraded Kimber RCA connectors and KCAG silver signal wiring, silver contact volume attenuators with HALCO resistors, Multicap PPFX-S capacitors and Caddock resistors.
Additional dampening was added to the chassis and the front panel thickness was increased. The Reference provided more independent supplies for the high and low voltage reference supplies and thicker umbilical cord for additional connections.
Our Testing Process for Preamplifiers at SkyFi:
We start with a visual inspection of all internal components to make sure there are no signs of stress or aging. Capacitors are checked for telltale sings of bulging or leaking, resistors are checked for signs of overheating or cracking, and transistors are checked for signs of stress or damage. Special attention is paid to the power supply which is the most common source of failure for preamps. We then power up the unit and run a simple 1k sine wave while monitoring the low voltage output on an oscilloscope for signs of distortion or noise to get a baseline.
At this point we will lubricate and clean all switches and potentiometers (that are not sealed) with a high quality contact cleaner, and then re-test all functions for any signs of noise or scratching.
Final testing involves putting actual music through the preamplifier We have learned over time that some issues are only noticeable to a trained ear while listening to a familiar source material. Our test bench has reference vintage Kef speakers that we are super familiar with which will quickly reveal any discrepancies. Some preamps will then move into the listening room where they will be tested with our in-house reference system.
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PURCHASING FROM SKYFI
This item will be professionally packaged and insured for safe transit to your home.
This item is also available for pickup in Glen Rock, NJ, with convenient parking near our building.
Click here for specifics on our specialized packing process that separates us from the rest.
If we don’t have the original manufacture’s packaging, we use heavy duty double-ply corrugated boxes with Instapak expanding foam custom inserts. In many cases this has proven to be better than the original packaging! We also use high quality fiber reinforced tape to seal our packages. Lightweight items will be bubble wrapped and shipped in a high-quality box.
NJ Residents or anyone picking up without a resale certificate will need to pay NJ Sales Tax.
Thanks for looking and be sure to call us at 201-879-0000 with any questions.
WHO WE ARE
SkyFi Audio is a small startup business specializing in the purchase, reconditioning, and reselling of select high-end audio equipment. We only buy equipment the we admire and are passionate about. No mid-fi, no gimmicks, no junk.
Each piece of equipment is cosmetically restored and fully tested in our well-equipped lab by an engineer with 30+ years of experience in the HiFi world. If it does not meet or exceed the original manufactures specifications, it will not be sold. We are very selective about the equipment we purchase, focusing on mostly analog, high-build quality, American, and European built units.
Through our sister company, which is an authorized dealer for McIntosh, Audio Research, Sonus Faber, ClearAudio, Pro-Ject Audio Systems, and Sony ES, we have access to OEM parts, service, and support. If you’re local and looking for new equipment from the above-mentioned manufacturers, please drop us a line as we can arrange both sales and professional installation in the tri-state area.
We do not accept or review any offers that do not go through the official Audiogon system. We have too many items for sale and it’s nearly impossible to keep track of offers outside of the official system. Please don’t message, email, or text any offers.
We prefer working through PayPal which allows you to use a credit card or bank transfer. We do not charge extra for any payment fees if you purchase the item at the asking price. You can also send us a personal check (which will need to clear before shipping), certified check, money order, or wire transfer. International clients without access to PayPal should use a bank wire transfer.
If you’re picking up an item we do not accept PayPal. You must pay in person with a certified or bank check, or wire transfer. If you make a PayPal payment and are picking up the item, your PayPal payment will be returned.
TRADE IN POLICY
We accept trade-ins of equal or lesser value under certain conditions. Simply click here to submit your gear for full consideration. We will only consider high-end equipment from mainstream manufacturers such as McIntosh, Mark Levinson, Audio Research, Krell, etc. and will typically pass on displays, projectors, receivers, dated surround processors, and mid-fi equipment of any type. We will offer a fair value for your equipment, but keep in mind we’re running a business and will need to be able to resell the equipment at a profit after investing a great deal of time and resources in testing, certifying, repairing, cleaning, and packaging the incoming equipment. If you’re looking for top dollar, we suggest selling it directly on your own.
SELL US YOUR GEAR (Working or Broken)
We’ll also purchase your used or broken gear and arrange pickup if you are in our local market. Simply click here to submit your gear for full consideration.
SCHEDULING AN APPOINTMENT
We are currently operating from our shop located inside our dedicated building in Glen Rock, NJ. You’re welcome to make an appointment if there’s a piece of equipment you’d like to see in operation before or after purchase. We have several well-equipped, dedicated listening areas plus a dedicated studio with tons of equipment of all makes and models. We’re not a store, so please don’t make an appointment if you’re just curious as to how a speaker or piece of equipment sounds. In essence - no tire kickers please.
You can call or text 201-879-0000 with any questions, or to schedule an appointment. We can also arrange to install, calibrate, and tune your newly purchased gear in your listening room if you’re local to our area. This is super useful when purchasing large speakers or heavy amplifiers. It’s also great for ensuring your new turntable is setup correctly in its final resting place.