[needanamp]

i heard that most speaker amps have ADCs in them? if so, this is surely a bad thing, as say you have an amazing DAC, but the ADC and corresponding DAC is likely to be of lower quality, considering you may pay $1000 for your DAC, and the ADC and DAC in the amplifier combined totals $80 or some small value. This is therefore a waste of your good dac and is not good for audiophiles.

so, can someone explain whether

A) speaker amps do have ADCs then DACs
B) why (i guess maybe to digitally equalize with bass and treble etc control -but why not do this in analogue???)

C) some speaker amps do not




thankyou.

 

[VicAjax]

A) no.
B) n/a
C) yes.

the only amps that would have ADCs in them would be class-D and class-T amps (digital-switching), as far as i understand. however, this isn't necessarily a bad thing.

standard tube and solid state amps do not have any conversion, unless they are HT receivers.

 

[needanamp]

The heart of an A/V receiver is the DSP, digital signal processor. It is used for tone control, speaker level balance, bass management and DSP effects like "Jazz", "Hall", even "Stereo" and decoders like Dolby Pro-Logic II and DTS:Neo 6. It can only work with digital streams, so any analog streams must be converted to digital using the receiver's ADC, analog-to-digital converter. After the DSP, the signal is then sent to the DAC like any other digital signal.

This extra conversion step will alter the sound. It can make it warmer (reduce treble) but may make it so warm as to be muffled in comparison to a digital signal which is sent directly to the DSP.


sorry, i got confused with a reciever. Why do SOME class D and T amp transform analogue signals to digital, then back again?

 

[Redo]

Many receivers have a pure mode, that shuts off all video circuitry and internal processing. This is great for analog sources and PCM sources, and it just passes the signal along to the AMP (or in the case of PCM, sends it to the DAC first)

 

[ls20]

class d aims for high power efficiency, so they use pulse wave modulation. the resulting square wave signals LOOKS like a digital waveform.

in car audio, class a/b are used for speakers (<6" drivers), and the efficient but less accurate class d amps are reserved for subwoofers

 

[roadtonowhere08]

The Crown XTi series have the Cirrus Logic CS4272 ADC/DAC. Supposed to be very high quality.

 

[VicAjax]

Quote:

Originally Posted by needanamp /img/forum/go_quote.gif The heart of an A/V receiver is the DSP, digital signal processor. It is used for tone control, speaker level balance, bass management and DSP effects like "Jazz", "Hall", even "Stereo" and decoders like Dolby Pro-Logic II and DTS:Neo 6. It can only work with digital streams, so any analog streams must be converted to digital using the receiver's ADC, analog-to-digital converter. After the DSP, the signal is then sent to the DAC like any other digital signal. This extra conversion step will alter the sound. It can make it warmer (reduce treble) but may make it so warm as to be muffled in comparison to a digital signal which is sent directly to the DSP.

this quote refers only to A/V Receivers designed for home theater... not to amplifiers in general. A/V receivers have to be able to process the digital signals from a DVD or other multi-channel media, so therefore they have built-in DACs. since they must have these processing abilities anyway, they usually include a whole slew of other digital signal processing doodads, which may or may not be of any use.

in order to use these DSP functions with an analog signal it may receive, the receiver will have to convert that analog signal into the digital domain, since that is where the processing occurs. then, in order to amplify the signal, it must be converted back into analog.

 

[VicAjax]

Quote:

Originally Posted by needanamp /img/forum/go_quote.gif sorry, i got confused with a reciever. Why do SOME class D and T amp transform analogue signals to digital, then back again?

my understanding of D and T amps is dodgy, but here goes:

the analog signal is converted to digital. the digital signal is amplified as a PWM signal through digital power switching, or pulses. the signal isn't converted back to analogue until the binding posts, essentially.

there are many high-end Class D amps on the market now, by Bel Canto, PS Audio, TaCT, Rotel and others... they mostly use an ICEpower amp module developed by Bang & Olufsen.

Onkyo has recently released a less expensive 2-channel integrated amp that uses Class D, and it's starting to get rave reviews. and Onix (AV123) is about to release a line of digital amps as well.

most of the Class T amps are low-power budget amps, the most famous being the Sonic Impact, which could be had at Target for $30 or less. it's starting to go a bit more upmarket. i saw something about a 60 watt T amp being made in Europe. that's pretty damn beefy for a T amp.