# Is my computer considered a "pre-amp"?



## rentonhighlands (Mar 24, 2010)

I am thinking of replacing my entire system. 
I am considering a pair of Mackie MR5's with a dayton sub (all self powered)
Is my computer considered a "pre-amp" or for this setup would I need a external pre-amp? I am just using onboard sound from the motherboard.
I was reading wikipedia and it states The preamplifier provides voltage gain (e.g. from 10 millivolts to 1 volt) but no significant current gain. For clarity would a seperate preamp be advised? 
I am just not sure how to connect the sub.
I know I can come straight out computers sound card and into the mackie's but how would I run signal to the sub?


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## jackfish (Dec 27, 2006)

What is the make and model of your sound card?


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## rentonhighlands (Mar 24, 2010)

I do not have a sound card I am using the onboard sound from the motherboard 
I have a ASUS motherboard model M4A785-M


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## jackfish (Dec 27, 2006)

You have an integrated sound card in that system. Here are the standard soundcard jack colors:
Lime Green- Line-Out, Front Speakers, Headphones 
Pink- Microphone 
Light Blue- Stereo Line In 
Orange- Subwoofer and Center out 
Black- Rear Surround Speakers for 5.1 and 7.1 systems 
Gray- Middle Surround Speakers for 7.1 systems 
Gold- Midi / Game port (Joystick) 
So you can hook the speakers up to the Lime Green jack (middle right) and the subwoofer to the Orange jack (upper left). You will need a 3.5mm stereo male to two RCA female adapter so you can run single RCA cables to each Mackie MR5 speaker and a 3.5mm stereo male to a summed RCA female adapter so you can run a single RCA cable to the Dayton subwoofer.


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## rentonhighlands (Mar 24, 2010)

When I run the sub using the orange output and the left and right speakers using the lime green output how does the crossover work. How does the sub know to only play the low freq?


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## nholmes1 (Oct 7, 2010)

Depends on the drivers and any plug-ins you have installed for your system. Some are more advanced than others and can go quite far into setup including room correction and a few other things. You could also use the built-in crossover on the sub to filter out frequencies about the range you don't want the sub to play.


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## nova (Apr 30, 2006)

Yes, I think you could consider your motherboard's audio out as a pre-amp.
Hook up as Jay says.
As for the crossover, use the Realtek audio software to set your crossover frequency.


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## jackfish (Dec 27, 2006)

> How does the sub know to only play the low freq?


The Dayton subwoofer also has a low pass filter (crossover).


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## rentonhighlands (Mar 24, 2010)

Would I get better sound using the high level inputs or the RCA inputs on the sub amp?
Or does it matter? 

I have decided not to purchase the makie's but to keep my current left and rights and purchase a Dayton 12" powered sub.

When I hook it up my left and rights are using my adcom amp. Does this mean I have to use the high level inputs on the sub amp?


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## jackfish (Dec 27, 2006)

I would use the RCA low level inputs of the subwoofer. Just run a 3.5mm stereo male to summed single RCA female adapter and a regular sincle RCA cable from the orange soundcard jack to the red/right subwoofer RCA input. Then set the subwoofer frequency level at about the low frequency -3dB point of your loudspeakers.


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## fschris (Oct 31, 2009)

I have tried what you are about to do. I used it for a bit but I ended up getting a Yammy RX-v765 which has preouts for amp hook up. I am using a Gigabyte e7aum... (great htpc mb). I found several issues using the MB as a pre amp but it can be done as suggested It is really better just to output a digital signal from the PC and use a RCVR to do the processing. One thing is if you want to listen to music.. for me I had to power up the plasma and PC getting everything to sync just to listen to some music... PITA! That is why it is nice to have a rcvr. The RX-v765 has really come down in price as well and is worth it IMO.


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## rentonhighlands (Mar 24, 2010)

fschris: thanks for the advice. There is no TV involved with my setup. I will be strickly using my set up to listen to music from my computer. Is there a different unit that I can use to produce the digital signal? Also a unit that would produce the digital signal and have inputs for EQ?


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## fschris (Oct 31, 2009)

Agh.... Okay well then go for it... Your PC will make a fine pre amp. For the most part. If you are not trying to decode DTS, BD, DD etc you should be fine.

also if you want to get all geeky google "m audio" ...p://www.m-audio.com/


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## rentonhighlands (Mar 24, 2010)

I purchased a sub. I found a great used sub. It is an AV123 sealed box with a new 10" driver using a 240 brand new Dayton SA240-B 240W plate amp. So I went to hook it up using the suggested setup in this thread from my MOBO. Not too much luck. All I am getting is a hum but no music at the sub but right and lefts are working. 
Here is the way I set it up that did not work.
Lime Green (RCA) 3.5 out to power amp>power amp to right and left using speaker wire
Orange (RCA) 3.5 out to right (red) and left (white) both plugged in to input on sub amp.
I get the music in the right and left speakers but no sound from the sub. 
To test I unplugged the right and left. I took the sub and plugged it into the Lime Green input and the sub gets signal and sound. I get music. 
So I am thinking it is something up on the MOBO side.
Can I have some help please? 
Thanks


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## fschris (Oct 31, 2009)

rentonhighlands said:


> I purchased a sub. I found a great used sub. It is an AV123 sealed box with a new 10" driver using a 240 brand new Dayton SA240-B 240W plate amp. So I went to hook it up using the suggested setup in this thread from my MOBO. Not too much luck. All I am getting is a hum but no music at the sub but right and lefts are working.
> Here is the way I set it up that did not work.
> Lime Green (RCA) 3.5 out to power amp>power amp to right and left using speaker wire
> Orange (RCA) 3.5 out to right (red) and left (white) both plugged in to input on sub amp.
> ...


Check out this link and see if that helps you out...

http://www.vistax64.com/drivers/185663-no-2-1-option-realtek-hd.html

make sure you have the latest drivers.

on the MOBO on jack sends out the center and the sub signals so you need a rca splitter.... if you are doing a 2.1 setup you need to go in the high level inputs i think from the lft and right channel.

but look over that URL i added.


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## rentonhighlands (Mar 24, 2010)

Yes I am doing a 2.1 setup. I am running WIN 7 64 Can I use a splitter on the line out jack? I am thinking I can do a spliiter on the line out to a 3.5mm RCA right and left to the power amp to power my right and left. Then on the same splitter use the 3.5mm to rca right and left to the power amp on the sub. Do they make a spitter like this?


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## rentonhighlands (Mar 24, 2010)

I think I may have found a solution. In winxp start>control panel>sounds and audio devices>audio>sound playback>advanced. At the advanced tab there is a drop down to choose 5.1 surround sound speakers ect. I think this turns on and off audio inputs and outputs. I hope WIN 7 64 has the same options. I will need to check this setting when I get home tonight I will post if this solves this issue. The link provided made me think to look at these options


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## rentonhighlands (Mar 24, 2010)

My solution solved my issue. I added a splitter to the lime green output. Everything works.


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## rentonhighlands (Mar 24, 2010)

Now I would like to add a EQ and a crossover to my system. What I am after is a software or a external hardware pieces not sure yet. This is the reason for my question. What would the forum suggest? 
Questions I have are: 

Is there a EQ made that has a seperate sub output? I find myself reaching around the sub to adjust the crossover and volume of the sub depending on what music I am playing. I would like to adjust the cross over and volume of the sub separate of its amp located at my computer. (I do not want to reach anymore) 

As for the crossover I am not sure I need this. However at this time the way I have my system set up is this. Computer is used as the pre-amp. Out from computer is a splitter one side RCA (left and right) going to the power amp and one side RCA (left and right) going to the sub amp. From the power amp I have speaker wire to the right and left loud speakers. At the loud speakers in each right and left are crossovers between each tweeter and driver. Right now the loud speakers are playing full range or maybe not because each has a crossover. What I am thinking is using a software or external crossover between the loud speakers and the sub. I am also thinking a digital crossover would create a higher quality sound.


Maybe the EQ is all I need. Please give me your thoughts.


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## fschris (Oct 31, 2009)

you should buy a receiver and mess around with it ... If you dont like it return it ... or get something used on ebay just to give your self a base line. something to reference.


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## jackfish (Dec 27, 2006)

You should not need to adjust the crossover on the subwoofer. No, a digital crossover is not likely to improve sound quality. Your loudspeakers already have a crossover employed to accommodate their high and low frequency sections (tweeter and woofer). The subwoofer has a low pass crossover so it is only receiving appropriate low frequencies. Set the "FREQ." dial as close as you can to the -3dB low frequency response of your loudspeakers and leave it. The "GAIN" dial should be set at the point where you turn it down to when you are listening to certain music or passages that make you want to turn in down. Then leave it there. The inherent low frequency rolloff of your loudspeakers should be enough to make it sound OK. If not, you could employ a passive high pass filter (again a frequency about the -3dB low frequency point of your loudspeakers) between the RCA adapter and the cable going to the power amp. Now, just sit and listen for a while and enjoy.

As far as EQ goes, are you looking for subwoofer EQ or broadband EQ? I really doubt with your system much will be gained. Proper speaker and sub placement, and perhaps some room treatment, will likely suffice.


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## rentonhighlands (Mar 24, 2010)

To answer this question As far as EQ goes, are you looking for subwoofer EQ or broadband EQ? I am looking for both. I want adjustablility on my desk. I find myself adjusting the EQ in Winamp alot.


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## rentonhighlands (Mar 24, 2010)

If I was to do this If not, you could employ a passive high pass filter would this help my loud speakers sound a bit brighter? To me the tweeter does not sound loud enough.


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## jackfish (Dec 27, 2006)

All a high pass filter is going to do is relieve your loudspeakers from producing low frequencies below the crossover point. It will not increase high frequency output. To do that, as you have discovered, you need to adjust the high frequency output in your system with tone controls or an EQ. I would suggest setting your WinAmp EQ to a level that provides the most satisfactory sound on most recordings and leave it there. Now stop listening to the system and start listening to the music. If you can't do that it sounds like you need to go out and audition loudspeakers and replace the ones you are apparently dissatisfied with.


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## atienza-ev (Jan 21, 2011)

Hello:

I would also like to use my MacBook as a "pre-amp", primarily to work around the configuration limitation of the Grant Fidelity TubeDAC-09, which is pre-wired for use as a DAC only. (The volume pot is only for the headphone amp. To use it as a pre-amp with the volume control on the unit requires some minor re-wiring and soldering that I would not be comfortable doing.) I would certainly prefer to use iTunes, Vox, or similar music player as a "pre-amp" because I could then use the Apple remote or even an iTouch or iPhone to control my music playback.

I intend to use the optical-out on my Airport Express to relay digital signals from my MacBook to the TubeDAC, then use the TubeDAC's RCA outputs to a new Velodyne VX-11 100-watt powered sub-woofer which will then power a pair of old Tannoy Mercury M2 loudspeakers.

Will this work, and work well? I hope so, as I am very excited by the potential of the low-cost, high-impact upgrades (TubeDAC and Velodyne subwoofer) to my music system. Thanks for your attention.


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## jackfish (Dec 27, 2006)

atienza-ev, Your scenario will not work as the speaker level input and outputs on that subwoofer are a pass through requiring speaker wire hookup to the speaker level inputs of the subwoofer from a receiver or amplifier which is then passed on to the speaker level outputs of the subwoofer along speaker wires to the loudspeakers. Nothing will come through the speaker level outputs if you are only hooked up to the subwoofer with the RCA inputs. Hence, you will need to add an amplifier to power your loudspeakers anyways.


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## atienza-ev (Jan 21, 2011)

Thank you, Jackfish. You are very astute and conscientious to have considered the "pass-through" jacks on my prospective new sub-woofer. (It appears that I will need a dedicated amplifier to drive my satellite speakers. Is there such a thing as a bi-amplified sub-woofer that will itself drive a pair of satellite speakers?)

But everything else should work, particularly using my Mac as a "pre-amp"? The point may be moot now since Rachel from Grant Fidelity has told me that they have for sale some TubeDACs pre-configured for use as pre-amps. Thanks again.


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## jackfish (Dec 27, 2006)

Usually subwoofers with speaker level inputs and outputs are a passthrough only requiring the power of an external amplifier to power the loudspeakers. Some subwoofers add a high pass filter, usually 80 Hz, to the speaker level output but yours just passes through unfiltered what is provided to the speaker level inputs. If you get a Grant TubeDAC09 configured as a preamp (which the current manual says it is) you can get a power amplifier to drive your loudspeakers. The Emotiva UPA-2 is $390 delivered or less used. Other used options should also be available. You could get a 50 Hz RCA inline F-MOD high pass filter to put between the preamp and amplifier and then set the subwoofer low pass filter to 50 Hz which should be a good starting point for your Tannoy M2s and Velodyne VX-11. Because your preamp has two RCA pair outputs you will be able to run signals to both your amplifier and subwoofer. I'd use the transistor output for the subwoofer and tube output for the amplifier/loudspeakers.


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## atienza-ev (Jan 21, 2011)

Thanks again, Jackfish. After a little more digging, I found this, the KingRex T20u amplifier. I think that I will forego the aforementioned system design:

MacBook>Airport Express (optical out)>new Grant Fidelity TubeDAC>new power amp>new Velodyne VX11 or comparable sub-woofer>Tannoy Mercury M2

with this one:
MacBook>new KingRex T20u DAC/amp>Tannoy Mercury M2

Simple, effective and affordable. I may even add now an optical-to-RCA adapter so that I can stream my music to my new system through my Airport Express. My upgrade path will then include first, either the matching KingRex power supply or a new/used sub-woofer or both. The KingRex components are especially appealing for their matching chassis.


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## fschris (Oct 31, 2009)

what is a mac book? oh i better not start ... lol


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## atienza-ev (Jan 21, 2011)

All of this research for a simple, affordable, does-everything well system greatly complements my obsessive-compulsive nature. With more digging I found these from Maverick Audio: the TubeMagic A1 Hybrid Integrated Amplifier and the TubeMagic D1 DAC

And their integrated chassis design appeals to my need for visual order, which is a symptom of my OCD.


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## rentonhighlands (Mar 24, 2010)

What devise can I get that will allow me to control the power of my subwoofer? I no longer want to reach around my sub box and turn it on and off all the time. The built in amp on the sub has the middle switch to set it to so when it is not receiving a signal it will auto turn off. My issue is that the way I have the sub hooked up is a splitter from my computer because I am using my computer as a pre-amp. My computer is on all the time therefore the sub is always receiving a signal. I am not using a receiver that has a sub out so I do not have the RCA connected in this way.

Maybe this? 
http://www.6moons.com/audioreviews/kingrex2/u.html


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