A preamp is a separate unit which sets between the source and the main amp. Having said that, sometimes a phono preamp can be incorporated in the turntable or the main amp, but it is still generally identifiable as performing a separate function (in this case, amplification and RIAA).
Sometimes people call a volume control in a box a 'passive preamp', but this is not really a preamp. It merely sits at the place in the audio chain where a preamp could sit.
A DAC would not normally contain a preamp. It will have I/V circuitry, which may include some amplification and filtering, but I would not call this a preamp.
Most modern systems do not need a preamp.
Sometimes people call a volume control in a box a 'passive preamp', but this is not really a preamp. It merely sits at the place in the audio chain where a preamp could sit.
A DAC would not normally contain a preamp. It will have I/V circuitry, which may include some amplification and filtering, but I would not call this a preamp.
Most modern systems do not need a preamp.
A pre-amp is for small sources: phono needle, microphone, tape head.
Traditional Tuners already made a Volt or more of output and did not need the preamp.
The pre-amp is to bring small sources up suitable for a Volume control.
A DAC works with several-Volt signals and does NOT need any "pre-amplification". It may need *filtering*, but that's different.
However we usually want a "post amp" between volume control and power amp. And we traditionally have Tone Controls, mono/stereo control, scratch filters, which are conveniently packaged together with the phono preamp, and the whole box still called "Preamp".
Traditional Tuners already made a Volt or more of output and did not need the preamp.
The pre-amp is to bring small sources up suitable for a Volume control.
A DAC works with several-Volt signals and does NOT need any "pre-amplification". It may need *filtering*, but that's different.
However we usually want a "post amp" between volume control and power amp. And we traditionally have Tone Controls, mono/stereo control, scratch filters, which are conveniently packaged together with the phono preamp, and the whole box still called "Preamp".
A complete audio path may start with a low-level source, mike, needle, tape head. Before we do anything else we must preamp it up near 1 Volt. Because records, singers, tapes may have different levels, this may really come to 2V or 0.2V.
Here we traditionally put a Volume control, so that later stages will not overload.
If the source and preamp happen to deliver 0.2V, this is all we can get out of a passive volume control full-up. (If they deliver 2V, we must turn-down.)
The power amp traditionally needs 1V or 2V for full output. We may want a weak recording to play loud.
Therefore we traditionally have a gain of 5 to 10 between the volume control and the power amp.
If ALL your sources are hot 2V sources, CD and DAC, then this added gain won't be needed.
Here we traditionally put a Volume control, so that later stages will not overload.
If the source and preamp happen to deliver 0.2V, this is all we can get out of a passive volume control full-up. (If they deliver 2V, we must turn-down.)
The power amp traditionally needs 1V or 2V for full output. We may want a weak recording to play loud.
Therefore we traditionally have a gain of 5 to 10 between the volume control and the power amp.
If ALL your sources are hot 2V sources, CD and DAC, then this added gain won't be needed.
I received a unit of SMSL M100 DAC from aliexpress.com. On specification, it outputs 2V. My aliexpress.com chinese no-name TPA3251/TPA3255 amplifiers also accept 2V as input. TPA3251 and TPA3255 accept 2V as input.
I discovered that if the right channel volume of M100 is 0dB, when the sound is loud, the right speaker emits a lot of crackles. If the right channel volume of M100 is -1dB or -2dB, the crackles stop.
I made sure to play the same audio data on the left and the right channels by editing and playing audio data in audacity.
I swapped RCA cables on my amplifier, and the crackles appear on the left speaker.
If I swap RCA cables on my amplifier and M100 DAC, the crackles appear on the right speaker. Thus, I concluded that the right channel of M100 DAC is abnormally higher than the left channel of M100 and that there is no problem with RCA cables and my amplifiers.
I filed a dispute to request a full refund with video evidences showing my discovery. The seller says my videos are not a professional test and thus I didn't prove that the product I received is a defective unit. I will have to escalate the dispute so that aliexpress.com intervenes.
Did I receive a defective DAC if the right channel of DAC actually produces crackles or clippings on the right speaker? My onboard soundcard doesn't have nearly as much channel imbalance as this.
Last edited:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.