Quote:
Originally Posted by efunroom
I am confused with low level and high level signal. Many DSP or AMP can accept both of them, but how to determine a signal is low level or high? Can I say line level is low level and speaker level is high level? differential signal is low and unbalanced signal is high?
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It is most simply defined as a voltage level. Higher levels can drive speakers. Lower voltages are called "pre-amp" voltages as they are not amplified enough to drive speakers. (This is somewhat confusing with OEM systems, as several OE amps, such as the BMW pre-bangle cars such as the E36 and E46, took high-level signals into the amplifier and there was no true preamp signal. But in the aftermarket, the signal to the amp from the head unit is always a low-level preamp signal.)
I avoid the use of the term "line level" because it means different things to different people, especially in pro audio compared to car. I always used it to describe low-voltage preamp signals, but pro signals can be very different.
Quote:
Originally Posted by efunroom
Technic said "... the HiFi OEM HU low level outputs can be used directly as inputs of the DQXS without any unnecessary high to low conversion as in the DQL-8". So the output of HU is low level and DQXS also regards it as low level input, but DQL-8 regards it as high level? When high to low conversion is required? it is device dependant?  |
You highlight a problem with many OE interface devices. It is difficult to make an input work with either a high-power speaker signal or with a low-voltage preamp signal. The initial Rockford 360.2 had problems here, as did the JL CleanSweep.
I am not too familiar with all the Audio Control products, but I think that technic is referring to the fact that some have RCA connectors and balanced circuitry on those inputs, and some have high-level LOC circuitry on bare wire inputs.
A true balanced input can accept low-voltage preamp signals, and it can accept medium-level speaker signals (such as from a deck or a small OE amp). It doesn't work as well with very high-power amplifier signals such as from bigger OE amplifiers. That's where the LOC inputs com in, such as in the LC6/7/8 and the DQL-8. The DQL-8 is essentially an LC8 and a DQXS in one box, with the signal going into the LC8, and the output of the LC8 going to the DQXS.
Quote:
Originally Posted by efunroom
Next question is about the flat signal. Can I think that All frequence waves in the flat signal has the same amplitude? What is the benifit to use a flat signal as input?
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Audio gear without any equalization or crossover filtering should amplify all signals equally - it should not emphasize some notes and attenuate other notes. The goal of good design of amps, speakers, etc., is to play all notes proportionally. This is almost impossible to achieve, but is the goal - and electronic components come far closer than speakers do.
A pink noise signal has equal energy at each octave.
Quote:
Originally Posted by efunroom
Back to my configuration, I am thinking about the DSP with digital SPDIF input since I plan to install a carputer. Using a sound card with SPDIF output, the SQ may better. OEM HU will take charge of RADIO. PC will play mp3 and DVD audio. Both of them can play CD. (I am not sure if PC can adjust the volume)
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OEM HU ----> DSP --> AMP(s) --> Speakers
PC ------>
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Alpine has some such products. for example PXA-701, PXA-H900, PXI-H990. Audison also announce the bit one, but I can not find bit1 in Audison website (out of market?). Any experience or suggestion about such DSP?
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Audison website is upgraded only every 3 years or so. Don't know if it is available in your market.
When working with SPDIF outputs, you will get much better sound quality than with most PC soundcards, but you will have a volume control problem. The control panel for the audison bitONE would solve that problem, I believe (again, Technic knows more about this product than I do, he has one and mine has not arrived yet). It sounds like you will want to do in-depth research on this question.