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Digital vs. Analog
jayess
post Aug 26 2012, 13:29
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Have patience, I'm a newbie at understanding the intricacies of good audio. Here's what I'm trying to make sense of: you go to buy cables and they rate them as RCA connections being the worst, optical/digital cables being the next step up, and HDMI the best. Then you start looking at things like Peachtree amps (stuff $1,000 - $2,000) and they only have RCA connectors.

How do you make sense of these inconsistencies?

And if you're going to use lossless, computer based audio to feed an amp what is the best way to go about this?
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LithosZA
post Aug 26 2012, 13:49
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QUOTE
And if you're going to use lossless, computer based audio to feed an amp what is the best way to go about this?

You could get an amp with a built in DAC with HDMI, Optical or USB inputs. All you need is 44.1Khz/16bit or 48Khz/16bit support. Going above this would not give you better quality.

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Have patience, I'm a newbie at understanding the intricacies of good audio. Here's what I'm trying to make sense of: you go to buy cables and they rate them as RCA connections being the worst, optical/digital cables being the next step up, and HDMI the best. Then you start looking at things like Peachtree amps (stuff $1,000 - $2,000) and they only have RCA connectors.

Those amps probably don't have built-in DACs so you need to purchase a seperate DAC and feed that analog output to the amp with RCA.
A lot of things in high-end audio don't make any sense.
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jayess
post Aug 26 2012, 15:02
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LithosZA' said "A lot of things in high-end audio don't make any sense."

Yes, if you apply common sense to the cable logic (HDMI being best), then everything, including sound cards, would all have HDMI outputs.
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[JAZ]
post Aug 26 2012, 15:09
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QUOTE (jayess @ Aug 26 2012, 14:29) *
[...]you go to buy cables and they rate them as RCA connections being the worst, optical/digital cables being the next step up, and HDMI the best.[...]


I would like to point out that it is not the cable or the connections the ones that are better or worse. The main question is the technology that is used with those cables.**

- RCA cables transmit analog audio. As such, there can be degradation in the first DAC, the transmission, and whatever other components are down the audio route. Also you need 6 cables to transmit 5.1 audio

- optical/digital cables ( i.e. S/PDIF) transmit digital audio. If the cable is optical (instead of electrical), ground loops or other interferences due to the connection are avoided. Still, S/PDIF is a realtime transmission protocol, so there is a clock for synchronization and delivery failures are possible. Transmission of 5.1 is possible, but there are limits on the total amount of data transmitted, and the highest sample rates would not be possible in that configuration.

- HDMI cables transmit digital audio. The transmission is done in packed streams (like ethernet cables or many other digital trasmission technologies). HDMI also has more codecs and gives control to the hardware/content makers to limit what you can output and what cannot. HDMI was made basically to transmit digital audio AND video.

- I guess we could complete the list with USB audio. This also transmits audio digitally, and i would consider it (as a technology) something between S/PDIF and HDMI. Many USB audio devices only support up to 48Khz audio, so in terms of audio quality, S/PDIF could be considered better.


Now, if you are really wanting to buy an amp to play audio from a computer, either get a good analog amp and good soundcard, or get a receiver that can receive HDMI or optical S/PDIF (most computers nowadays should have one of those outputs, and if not, buy a soundcard with them). The good thing about a receiver is that you get analog and digital connections, and can connect other inputs as well.



**Note: Cables and connections can make a difference, but only in concrete scenarios, like long distances and high wattage (i.e. in a concert) or degradation over time (i.e. contacts getting oxidized, or disconnecting unexpectedly)
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jayess
post Aug 26 2012, 15:21
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You'll probably laugh at this next question, but as they say, the only dumb question is the one that doesn't get asked. If you're soundcard has analog outputs can it go straight to an amp without having a preamp? Will the soundcard take the place of a preamp or will you need all three?

This post has been edited by db1989: Aug 26 2012, 15:33
Reason for edit: deleting pointless full quote of above post
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Arnold B. Kruege...
post Aug 26 2012, 15:58
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QUOTE (jayess @ Aug 26 2012, 08:29) *
Have patience, I'm a newbie at understanding the intricacies of good audio. Here's what I'm trying to make sense of: you go to buy cables and they rate them as RCA connections being the worst,


With the caveat that in general all cables and all connections are capable of being free of audible imperfections.

QUOTE
optical/digital cables being the next step up, and HDMI the best. Then you start looking at things like Peachtree amps (stuff $1,000 - $2,000) and they only have RCA connectors.


Any good modern AVR has RCA connectors and optical and coax digital inputs, and HDMI inputs. The error is presuming that just because Peachtree has a certain reputation and price, it is necessarily any better sounding. In fact in a well-optimized system, the AVR will probably sound massivly better or at least has that potential.

QUOTE
How do you make sense of these inconsistencies?



I don't see any other than perhaps the rotten price/performance of Peachtree's line of products. It is boutique stuff.

QUOTE
And if you're going to use lossless, computer based audio to feed an amp what is the best way to go about this?


Another relevant point - just because it is lossless doesn't mean it necessarily sounds better.

The most flexible way to convey audio from recordings to a receiver is probably HDMI.
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[JAZ]
post Aug 26 2012, 16:06
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QUOTE (jayess @ Aug 26 2012, 16:21) *
You'll probably laugh at this next question, but as they say, the only dumb question is the one that doesn't get asked. If you're soundcard has analog outputs can it go straight to an amp without having a preamp? Will the soundcard take the place of a preamp or will you need all three?



If you get a power amp (i.e. a pure amplifier only, like what is used to build speaker towers for concerts), then they just amplify (power) the signal coming in. If the signal is line level, the final output will be lower than if it is preamplified. [edit: Probably there could also be line level differences, since there are two standards. Read the _second_ post of this thread for a rather good explanation: http://www.gearslutz.com/board/high-end/56...an-exactly.html ]

But most consumer/prosumer amplifiers are integrated amplifiers (i.e. amplifiers with a volume knob and maybe several switchable inputs).

This post has been edited by [JAZ]: Aug 26 2012, 16:16
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jayess
post Aug 26 2012, 16:53
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QUOTE ([JAZ] @ Aug 26 2012, 10:06) *

QUOTE (jayess @ Aug 26 2012, 16:21) *
You'll probably laugh at this next question, but as they say, the only dumb question is the one that doesn't get asked. If you're soundcard has analog outputs can it go straight to an amp without having a preamp? Will the soundcard take the place of a preamp or will you need all three?



If you get a power amp (i.e. a pure amplifier only, like what is used to build speaker towers for concerts), then they just amplify (power) the signal coming in. If the signal is line level, the final output will be lower than if it is preamplified. [edit: Probably there could also be line level differences, since there are two standards. Read the _second_ post of this thread for a rather good explanation: http://www.gearslutz.com/board/high-end/56...an-exactly.html ]

But most consumer/prosumer amplifiers are integrated amplifiers (i.e. amplifiers with a volume knob and maybe several switchable inputs).


Thanks. I was actually referring to something like the Onkyo M-282.

http://www.vanns.com/shop/servlet/item/features/531299905

Again, common sense says you have the soundcard and computer to select the inputs and control the volume, so from the standpoint it made me ask if you really needed the preamp.
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jayess
post Aug 26 2012, 17:00
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Arnold B. Krueger said "The most flexible way to convey audio from recordings to a receiver is probably HDMI."

Yes, but the soundcards such as a Xonar or Soundblaster X-FI don't have HDMI out; they're optical and S/PDIF.

Again, me trying to learn and understand this stuff: isn't the final output coming out of a amp or receiver ultimately an analog signal? Even if you're inputting digital from a S/PDIF cable or HDMI, isn't the end result ultimately converted to analog?
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Apesbrain
post Aug 26 2012, 18:04
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QUOTE (jayess @ Aug 26 2012, 10:21) *
You'll probably laugh at this next question, but as they say, the only dumb question is the one that doesn't get asked. If you're soundcard has analog outputs can it go straight to an amp without having a preamp? Will the soundcard take the place of a preamp or will you need all three?

Yes, the analog output of your sound card can go directly to the analog inputs of a power amp. If you are otherwise happy with the sound coming out of your PC (e.g. as heard through headphones) then there is no reason to believe you won't be happy with the result.

One risk of this approach is that there is no volume control -- typically part of a separate pre-amp -- between the PC and the power amp. Although volume can easily be controlled by most software music players, there remains the concern that a full-scale signal could be sent to the power amp either by accident or by someone not knowing what they were doing. Not only would this be unpleasantly loud, it would also likely damage your speakers. One nice feature of the Onkyo power amp you linked is that it has an "Input Level" control on the rear panel. Use this to set the maximum volume that you might ever want to listen with all your software volume controls set at full and then you never need worry about it going any higher.
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Roseval
post Aug 26 2012, 18:18
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Connecting a sound card to an amp is the same as connecting a CD player or a tuner or any other source.
A pre-amp can do a couple of things like choosing the source, tone control, volume control, etc.
It also amplifies.
A power amp simply amplifies.
If you connect a source directly to a power amp you are missing the gain of the pre-amp.
It can be done but you canít play loud as you are missing the gain of the pre-amp.


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greynol
post Aug 26 2012, 18:28
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Assuming we're talking about about components that provide a consumer line level output into a power amp that expects full-scale to be conumser line level, then the preamp isn't providing any positive gain.

If we're talking about a turntable and/or power amp that expects commercial pro-audio line level and doesn't compensate for conumer line level then gain will be necessary.

This post has been edited by greynol: Aug 26 2012, 18:33


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[JAZ]
post Aug 26 2012, 19:47
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QUOTE (jayess @ Aug 26 2012, 18:00) *
Again, me trying to learn and understand this stuff: isn't the final output coming out of a amp or receiver ultimately an analog signal? Even if you're inputting digital from a S/PDIF cable or HDMI, isn't the end result ultimately converted to analog?


Yes. What drives the speakers is an analog signal.
Generally speaking, the goal is to reduce the parts where the signal travels in analog form, as well as maximizing the quality of the DAC. (These days this shouldn't be too complicated).
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jayess
post Aug 29 2012, 18:13
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QUOTE (Apesbrain @ Aug 26 2012, 12:04) *
QUOTE (jayess @ Aug 26 2012, 10:21) *
You'll probably laugh at this next question, but as they say, the only dumb question is the one that doesn't get asked. If you're soundcard has analog outputs can it go straight to an amp without having a preamp? Will the soundcard take the place of a preamp or will you need all three?

Yes, the analog output of your sound card can go directly to the analog inputs of a power amp. If you are otherwise happy with the sound coming out of your PC (e.g. as heard through headphones) then there is no reason to believe you won't be happy with the result.

One risk of this approach is that there is no volume control -- typically part of a separate pre-amp -- between the PC and the power amp. Although volume can easily be controlled by most software music players, there remains the concern that a full-scale signal could be sent to the power amp either by accident or by someone not knowing what they were doing. Not only would this be unpleasantly loud, it would also likely damage your speakers. One nice feature of the Onkyo power amp you linked is that it has an "Input Level" control on the rear panel. Use this to set the maximum volume that you might ever want to listen with all your software volume controls set at full and then you never need worry about it going any higher.


Update: I took the plunge and went with two of the Onkyo M-282 amps fed into some KEF XQ 20's in a vertical bi-amp configuration. I used two Monster Y-cables to split the L/R coming out of the Xonar into each amp. Set the line level at 50% (which may still be too high for what I need) and it's working like a dream. Vann's has the Onkyo M-282 amps on sale for $199, so it wasn't expensive to set this up at all.

Thanks for the advice!

This post has been edited by jayess: Aug 29 2012, 18:55
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