Full Volume Issue


I have had the strangest thing happen to me twice. With my Nu-force P8 preamp in the off position while my cd player and dac are on there is no sound. If I turn on my tv then what is on the cd player comes on at full volume. The first time I turned on the tv and this happened it scared the hell out of me. The preamp didn't have any power to it. How is this happening?
philbrady

Showing 1 response by studio1

Friend

I am assuming that your TV is not connected to your preamplifier. If this is true - then you may have a rare occurance where a microprocessor inside your preamplifier is reacting to signals from your TV remote control!

The fact that the preamplifier does not power up means nothing. In the easiest terms - one of two things sounds like it's happening: 1) the CD Player is sending signal to the preamplifier to preamplify, and the TV remote triggers a microprocessor to a open circuit allowing the 2.3 volt CD Player signal to flow straight through, or 2) you have your CD Player in input #3 which allows signal bypass. If you look below at the specs for your pre you will see that the P8 has this capability. See "input 3".

Specifications:

Audio inputs: 3 sets of RCA inputs and a 3.5mm stereo input jack (for digital media player, PC sound devices). Input 3 can be custom ordered from factory with volume fixed at 0db (gain=1) for Home Theater or PC pass-through.
Audio outputs: 1 set of RCA, 1 set of Balanced XLR, and a 3.5mm stereo headphone output with cross-feeding to create a natural soundstage.
Remote input selection and volume control with memory (last selection, volume level)
Mute and Sleep functions
Digitally-controlled switched attenuator. Volume Range: +30dB to –70dB with 0.5dB steps
Dynamic Range: > 100dB

Input Impedance: 4K ohm
Output Impedance: 40 ohm
THD+N at 1kHz: < 0.01%, typically 0.003-0.005%
S/N Ratio > 85dB
Frequency Response at 20-20kHz = +0dB/-0.2dB at 20-170kHz = +0db/-3dB
Maximum output = 8V RMS
Crosstalk –130dBFS
100W SMPS with PFC (Power Factor Correction)
Dimensions: 1.75”H x 8.5”W x 16”D Weight: 6 lbs.
Power Requirements: 90-240VAC, auto select.

Now, how to fix it! Here are two ways:

1) Send your CD Player through another input.
OR
2) Make sure that you have a power-up and power-down procedure set in place where your amplifier or CD Player are not at the same time.

The reason why you get a RUSH of volume is that there is no preamplifier in circuit to regulate the signal that is being sent dirtectly to your amplifier! So, in effect what you are doing is the equivalent of plugging your CD Player directly into your amplifier with no volume control.

Some people use the first to avoid a thump during power-up on sensitive units.

Hope this helps
Studio1