Do I need a pre-amp?

jwl

Hello,

I am trying to figure out if I need a pre-amp or not. I have received different answers from different manufacturers, so I would like your help in understanding why I would need/want one. What I am trying to do is connect regular speakers to a computer (sound card).

I bought an AMP, but it was DOA so I am in the process of shopping for an AMP to use with the equipment below. It is on another thread, but so far the leading contenders for a new AMP are ADCOM GFA-535, ATI AT602 and Emotiva UPA-200.

I have a Klipsch Promedia DD5.1 preamp/decoder, but I am not sure if that will work as a pre-amp for this type of equipment. If you know, please let me know.


Here is the equipment I am using (I pasted links to manuals below).

Polk Monitor 40 Series II
Polk PSW10
HT Omega eClaro (PC sound card)
If needed, I have a Klipsch Promedia dd 5.1 preamp/decoder

Polk Monitor 40s: http://ec1.images-amazon.com/media/i...L000074437.pdf
Polk Sub: http://www.polkaudio.com/downloads/m...SW10_12_MN.pdf
HT Omega eClaro: http://www.htomega.com/filedown/eclaro.pdf

klipsch dd5.1:
http://www.klipsch.com/promedia-dd-5-1
http://www.themusichelpers.com/z/248061100000001


Thanks!

J

jwl

I found out from HT Omega that the eClaro RMS value is 2.8Vpp/2Vrms. Is that enough for an AMP? Do different AMPs require different or more?

dudeinaroom

That should be more than enough to drive an amp. Using the "headphone" style analog connections is not seen as having the best quality for sound reproductions. Using the optical digital connection would be ideal. Running the signal into the Klipsh should be a better way to go. Are you looking to go with surround or just stereo? If you are planing on going stereo a separate DAC paired with either an integrated amp or a preamp/amp combo would be better.

jwl

dudeinaroom - Right now, I am just trying to connect the computer to a pair of speakers and a sub woofer and control the sound with the computer. I happen to have the Klipsch. My understanding is that the HT Omega eClaro in this setup is the DAC. I know I need an amp in between. The question is do I also need a pre-amp.

Where I am struggling is that folks seem to differ as to what the voltage rating for input signals means to an AMP. For example, the ATI AT602 says it requires .9 volts. The sound card puts at 2 volts. Some people are telling me that this will result in the sound card telling the amp to play at full volume and therefore I must have a pre-amp to prevent me from blowing my speakers. Others are saying the .9 volt rating is the minimum voltage required for the AMP to comprehend that sound is being sent to it.

11tsteve

hook everything up and see what works best.

" For example, the ATI AT602 says it requires .9 volts. The sound card puts at 2 volts. Some people are telling me that this will result in the sound card telling the amp to play at full volume and therefore I must have a pre-amp to prevent me from blowing my speakers.".............

this doesn't make sense to me. you will be controlling the gain of your signal via the volume of the computer, no matter what you hook up. the computer will be acting as your DAC/preamp, if it works, and so will stop the amp from just playing full volume all the time.

make sure the volume control is off before you hook stuff up and play any music.


even though i run TOSLINK out to external separates, i can still use my computer volume of i wish. but, i choose to use the computer volume at 100% gain all the time, because i believe that will be the bset quality output signal, and i use my pre-amp volume knob. you seem to be hung up on controlling the volume from the computer...its really not an issue to make it so no matter what the external equipment. it is more dependent on how you set up the computer to deal with sound... i.e. drivers.
make sure the volume control is off before you play any music.

dudeinaroom

.9 volts is what it would take to get the amp to full volume, you could very easily overdrive the amp if you are not careful with the computers volume control. I don't know what the voltage is for full volume of the sub, so you could end up with a miss match in volume. Now if the sound card has individual volume controls for each channel you could turn down the front left and right volume sliders so you would have more flexibility with the master volume and also match the sub better per it's slider in your sound cards software. Ideally for better sound quality you would want to use an external DAC instead of the one on the sound card. For your need though the sound card may be enough for you.

jwl

I am using an HT Omega eClaro for a sound card. What does an external DAC get me that the sound card does not? This could be a two part question. First, is an external DAC better then my sound card period and if so, why. Second, I am assuming there are different quality DACs, so it would help to know what I would need to look for in a DAC to improve over what I have and determine how much improvement exists.

dudeinaroom

An external DAC has it's own power supply, so you don't get the noise that comes from a computers supply that is powering multiple components. The build quality is usually better in a separate outboard dac and uses higher quality components in the audio chain instead of the smallest, cheapest that will fit and work. There is no shielding on an inboard to keep out stray rfi which the inside of a computer is filled with. Most also consider the headphone style plugs to be an inferior audio connection, and a computer db style plug to be even more so, which the wiring harness for audio connections on that card have both. As far as the actual cards quality I have no Idea, it could be the best in the world. This is just how most see it. Now whether or not you will hear the difference is the determining factor in which route you take.

jwl

What makes a great DAC?

dudeinaroom

Too many factors to list from design, implementation to components used. Best bet is to jump on the net and do a little research and read some reviews. You could also use a search engine and type in DAC site:polkaudio.com/forums to see what is on here.