Summary of Contents for Musical Concepts PasPro 1
- Page 1 Musical Concepts PasPro 1 Vacuum Tube Modification for Hafler DH-101 Preamplifier...
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Page 2: Circuit Description
It is directly dependent on the mu(gain) of each tube. Obviously matched tubes are strongly recommended. The PasPro 1 line stage is a single stage grounded-cathode amplifier with about 24dB gain. That is correct, there are only three amplifier stages, making the PasPro 1 an incredibly straightforward design. All tubes are the 6DJ8/6922/Russian 6N23P type. -
Page 3: Installation Instructions
We recommend that you read through the instructions completely before beginning the modification to determine if you will need the assistance of an experienced friend or professional installation by Musical Concepts. TIP: To deburr a hole you might use a Dremel tool or a much larger drill bit for a drilled hole. - Page 4 5.( )If you are keeping two phono inputs cut the wires connected at 1R/2R and 1L/2L underneath PC-4 by cutting them flush. These eyelet labels are “printed” in circuit foil on the underside of the Hafler PC-4 board. If you are adopting a single phono input approach cut all the insulated wires from the Phono 1 and Phono 2 RCA input jacks.
- Page 5 Preparation of PasPro 1 board for installation 17.( )Your heater voltage regulator is pre-installed with flexible wire leads. >>>>The remainder of this step is a sort of assistance for those who might want to use a different voltage regulator for whatever reason.<<<<...
- Page 6 Phono 1 input RCA jacks on the rear panel to the PP1. Musical Concepts(MC) provides two lengths of shielded 2-conductor cable with bare shield drain wire. On the RCA jack end you will connect all three wires.
- Page 7 29.( )If you have purchased the Alps blue volume control, Fig 12, with your PP1 you can now install it. If you have your own control to use then just follow the basic procedure outlined here. For the mechanical install the details are at the left.
- Page 8 The transformer is mounted in place and ready to be energized. You should have the transformer’s connector just to the left of the power supply partition very near the power connector of the PP1. Give the chassis a sharp rap to dislodge any mischievous wire clippings. ALWAYS REMEMBER THAT THERE ARE DANGEROUS AC AND DC VOLTAGES PRESENT IN A PP1 INSTALLA- TION.
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Page 9: Performance Options
Please let us know your thoughts on your registration card. WARRANTY: The parts used in Musical Concepts modifications are warranted for a period of 1 year from the date of original sale to the original purchaser with the exception of vacuum tubes which are warranted for 90 days. Original Hafler parts are not covered. Parts clearly damaged by the installer are not warranted. -
Page 11: Left Side
Left Side 4 13/16” 1/4” Chassis lip... - Page 12 AMPLIFIER CIRCUIT: Parts for amplifier circuitry begin with 1, for example, R1 is left channel and R101 is right channel. CAPACITORS: Some may use their own parts. Guidelines given. PREAMP STAGES: 1 - PasPro 1 board(bare), Rev D C1,101: 220pf supplied or user’s cartridge matching value(any voltage) RESISTORS: All 1%, ¼...
- Page 14 Musical Concepts PasPro 1 will look like this installed into your stock Hafler DH-101. You can do it equally well. Optional connectors, etc. could be in- stalled.
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