pre-amp

[rlaakso]

<font color='#000000'>I am upgrading a fairly old system. I have a late 1970's pioneer SX-1280 receiver (185 watts per channel). It is in the repair shop as of yesterday. The kids are finally out of the house, and I can set up our finished basement for myself! I will be picking up some KEF Reference 4-2 4 OHM speakers that I purchased on Audiogon. Rainy day today, so I have been researching on the internet about pre-amps. I cannot find the basics, mostly sites that want to sell me something. What is the difference between a pre-amp, and my existing power amplifier? I use it for two channel stero listening. My home theatre set-up is in the same room, but the two systems are separate. How do I hook up the pre-amp? I assume it is hooked up to the Pioneer, but as I say, I cannot find any info this basic on the internet, so I am looking for help on this forum.

Thanks for the help,
Richard Laakso

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[Guest]

<font color='#000000'><table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE">I have a late 1970's pioneer SX-1280 receiver  . . . . .What is the difference between a pre-amp, and my existing power amplifier? </td></tr></table>

I'm not clear what you are using for which system, but let me clarify some terms:

Stereo Systems
1) Stereo Preamp is typically just a multi-source selector and a volume control.

2) An Integrated amp typically adds two amps to a stereo preamp.

3) A receiver typically added an FM tuner to the intergrated amp.

HT Systems
1) Prepro is a multichannel preamp + DD/DTS decoder + DAC

2) Receiver adds 5-7 amp channels to the prepro and maybe an FM tuner.

3) Multichannel amps come in many sizes, 3-7 channels
_

Now, about integrating your current stereo preamp and amps with an HT system, here is what you need to know:

1) Your HT prepro/receiver must have RCA outputs labeled L&amp;R preouts

2) You connect those HT L&amp;R preouts to an AUX L&amp;R input on the stereo preamp.

3) The center and surrounds are handled by your HT receiver.

4) When you do your speaker calibration with the HT prepro/receiver, simply use the stereo preamps volume control to set the L&amp;R SPL levels (you should use a Radio Shack SPL meter).

Now when using the the 2-channel system, you don't need to turn on the HT system at all.

Hope that helped some.</font>

 

[rlaakso]

<font color='#000000'>Thank you for your response.

I have an HTS system in place. It is 5.1, and works great. It is the older 2 channel system that I am setting up, strictly for audio. The pioneer has a tuner allready. I only want to use the pre-amp for the two channel system. Eventually I want to Bi-amp the speakers. I know that this is very controversial, so that is why I say eventually.

I take it that the pre-amp does not increase the power to the speakers. It only provides a cleaner signal from the source. Is this true for my situation?

A brief glance on prices leads me to believe that pre-amps, on average, go for more $$$ than an amplifier. Thus they must be important to the audio system.

I suppose I should have posted this in the beginners forum, because in some ways I am.</font>

 

[Guest]

<font color='#000000'><table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE">I take it that the pre-amp does not increase the power to the speakers. It only provides a cleaner signal from the source. Is this true for my situation? </td></tr></table>

Essentially the idea in 2-channel is to keep the signal as clean as possible from the source to the speakers.  

The problem is most CD players and turntables don't have volume controls, and most amps don't have volume controls.  If you were to hook the CD player directly to the amp it would always be at maximum volume, i.e. too loud.

So, a 2-channel preamp is designed to give you a selector for picking the source (CD player, turntable, tuner, etc.) and a volume control (hopefully with a remote) so you can adjust the volume sent to your speakers.

To integrate a 2-channel preamp into an HT system is not hard, and you may get better sound (than hooking the CD player directly into the HT receiver), because all the extra circuitry (video and DSP chips) in the HT receiver makes it a noisier environment for the music signal than a 2-channel preamp and amps.  So yes, it may provide a cleaner signal for you from your source.

There are basically two kinds of 2-channel preamps; active and passive.  The passive preamp cannot increase the signal strength to your amps-->speakers, it can only decrease (attenuate) the signal.  An active preamp can increase the signal strength to your amps-->speakers, and can also decrease it.

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE"> A brief glance on prices leads me to believe that pre-amps, on average, go for more $$$ than an amplifier. </td></tr></table>
Not necessarily, it all depends on what you want. &nbsp;You can start with 2-channel preamps at $200.</font>

 

[rlaakso]

<font color='#000000'>My amplifier (Pioneer SX-1280) has volume control. Does this mean I have little use for a pre-amp?</font>

 

[Guest]

<font color='#000000'>I'm a little unclear about your current setup, how about telling me a little more:

Your Stereo System
1) Pioneer SX-1280 receiver, which is a combined preamp+amp in one unit (does it also have a tuner?)
2) KEF Reference 4-2 4 OHM speakers (soon to arrive)
3) Source units? (CD player, turntable, tape?)

Your HT System
1) HT receiver?
2) DVD player?
3) Current Main L&amp;R speakers
4) Surround speakers?
5) Center speaker?
6) Powered Subwoofer?

_

I expect the Pioneer SX-1280 with its 185 watts/channel (is that the 8 Ohms rating?) may drive the 4 Ohm KEF speakers just fine.

If your HT receiver has RCA L&amp;R preouts, then you can begin by just connecting these L&amp;R preouts to any spare AUX input on the Pioneer SX-1280 to start your journey integrating your 2-channel with the KEFs as main L&amp;R speakers into a joint 2-channel/HT system.

And yes, you don't need a preamp to start this journey if the Pioneer SX-1280 is truly a stereo receiver and has a volume control. &nbsp;I'm just assuming you're calling the Pioneer SX-1280 an amplifier when it's really a receiver, is this true?</font>

 

[rlaakso]

<font color='#000000'>Yes, the SX-1280 is a receiver with a tuner, and volume control. It is typical of a high-end tuner-receiver of the 1975-80 era. The only input that I am now planning for this receiver is a CD player. I am looking for an excellent audio experience with a two channel system (of course many others are looking for the same thing).

My HT system is set up with an Onkyo TX SR-700 receiver, a Toshiba SD-2200 DVD player, Infinity Overture 2 front speakers, and center channel speaker. The rear surrounds are not matched to the Infinity speakers.
I now understand that the amplifiers of today do not have volume control. I am the original owner of the Sx-1280, and have taken this feature for granted. Now I understand why some people are willing to pay $600 for my receiver on Ebay. It is in excellent condition.

It looks like I need to Bi-amp these speakers with an active crossover, and not a passive one. Perhaps I should look for another SX-1280 on Ebay to do this. I know that bi-amping is controversial, but I believe that if it is done properly it can enhance the sound coming from the speakers.

Why do amplifiers not come with volume control? I didn't consider this with my original post.</font>

 

[Guest]

<font color='#000000'>Actually, some amplifiers do come with volume controls.  For example my Parasound 1205a 5-channel THX amplifier has 5 volume controls, one for each channel on the same back panel as the RCA input and speaker output connectors.

There are other amps with volume controls as well, it's just not a standard.

So I take it you liked the SX-1280 as the central controller for your 2-channel system.  Does it have small metal U shaped jumpers from L&amp;R pre-out to L&amp;R amp-in RCA connectors?

If so, then you can integrate it into your HT system and use an active crossover plus another amp for the bass portion of your bi-amped L&amp;R main speakers.  You might even get a bigger amp instead of another SX-1280 for the bi-amped bass portion of your system since bass takes the most power.</font>

 

[rlaakso]

<font color='#000000'>Bruce'
Yes it does have the jumpers. I am pondering what you are saying here. Why would I want to incorporate my two channel system into the 5.1 system? Would this give me 4 front speakers? Isn't that overkill?

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[Guest]

<font color='#000000'>I thought the orignal objective was to integrate everything into a single control center and provide for dual use.

Obviously even with separate systems in the same room, they can't be used at the same time.  So, instead, integrating them into a combined 2-channel/HT system would allow you to leverage your investment.

No, actually 4 main front speakers isn't the objective, using the same 2 front speakers for both 2-channel listening and HT use was the thought here.

If integrating the 2-channel and HT systems together wasn't your original intent, then you can still upgrade your 2-channel system with outboard amplification for bi-amping the new KEFs from the SX-1280 by adding an active crossover and another stereo amp.</font>