Connecting pre-out to a Pre-amp

[silentsound]

Hi,

Is it ok to connect the front L/R pre-out from the AVR to one of the input in the stereo pre-amp? I'm trying to use the same set of speakers for music and movies. As per the AVR spec, the pre-out is 1.0V/500 ohms and the pre-amp spec says maximum input impedance is 47k/200pF and max input signal is 10V.

Thanks,
SilentSound.

 

[hifipal4all]

It is not advisable to connect this way. Generally any pre-out signal has to directly go to the power amp's input. If you connect it to stereo pre-amp's in, there will be distortion in the output when you increase AVR's volume beyond certain point.

If you want you can just try this method ... connect the L/R pre-out of the AVR to one of the input in the stereo pre-amp and just keep the AVR's volume level to very minimal level and use the stereo pre-amp's volume control to vary the volume. The AVR's volume must remain in the same position.

Cheers,
Ramesh

 

[silentsound]

Hi Hifipal4all,

Makes sense to keep the avr volume to minimum. Thanks for the idea. Let me try it out and let you know.

SilentSound.

 

[flanker.r]

Are you connecting one speaker to both the strereo amp and avr amp at same time. the protection devices will kick in as current will try to flow from one amp the other and power up the output transistors. This will happen when both amps are switched on at same time

Also when you keep avr volume at min, no signal will be sent to your stereo preamp. remember, volume controls are always part of preamp circuit. Use tape out of AVR and feed it into your stereo preamp input but do not connect two amps to same speaker . This is dangerous to the amp!!!!!!

 

[silentsound]

Hi flanker,

Thanks for the warning. I was not going to connect two amps (avr, stereo amp in my case) to the same speaker.

This is what I'm trying to do:

CD Player -> Stereo Pre(CD Input) -> Stereo Amp -> Front Speakers.
DVD Player -> AVR Preout -> Stereo Pre (Video input) -> Stereo Amp -> Front Speakers.

Sub, Center and surround speakers are connected to the AVR.

As for as the volume is concerned this needs to be set using the spl meter as one of the other member (relativex I think) suggested.

Cheers,
SilentSound.

 

[murali]

Silentsound,
I am running my system exactly as you wish to. Instead of AVR I use a surround processor/preamp whose output goes to my stereo preamp. I try to set the stereo preamp volume constant and close to unity gain (11'o clock or 12'o clock position) and then control the entire 5.1 speakers volume using the processor volume control. No issues and works fine.
Some stereo preamps come with home theater (surround processor) pass-through provision (unity gain) in which case you don't have to touch its volume control. Otherwise, this is what everyone does.
Trust this helps.

> murali

 

[hifipal4all]

CD Player -> Stereo Pre(CD Input) -> Stereo Amp -> Front Speakers.

This is absolutely fine.

DVD Player -> AVR Preout -> Stereo Pre (Video input) -> Stereo Amp -> Front Speakers.

Do not try or connect this way. Already you will be getting variable output from your AVR's Preout and again you are trying to route this variable output to a Stereo Pre's (Video input) and this signal level is again controlled by the Stereo Pre's volume control which is totally incorrect. It is like trying to connect 2 preamps in series for one Stereo Power Amplifier

This is the right method ....
1) Use a Coaxial cable or an Optical cable from the DVD player to the AVR for Centre channel, Surrounds & Subwoofer.
2) Use a 2 RCA cable and connect the AVR's Front speakers analog preout to a Stereo Power Amp and not to a Stereo Preamp or a Stereo Integrated Amp.
3) Ensure that the wattage of the Stereo Power Amp is equal to AVR's front channels wattage as per AVR's specs.

Cheers,
Ramesh

 

[flanker.r]

Ramesh is right.

Thats the correct way to go about connecting.

Only thing to add is, you should not power on both the amps (the avr and stereo amp) at same time, if both the amps are connected to the same speakers. if you do, power from the amp that is playing will try to pass into the output transistor of another amp and the protection circuitry will kick in and shut down the 2nd amp

 

[flanker.r]

Hey sorry dude,

you have already clarified that you would not be connecting two amps to one system. missed that!

 

[Sumit]

Hi Ramesh!!

I am unable to understand your solution. I think our friend here wants a to use AVR, Stereo Pre and Stereo power along with CD and DVD player.
Your solution eliminates the stereo pre amp. Maybe you can help me understand your solution.

I suggest two options to your problem:

Option1: I feel our friend wants to use AVR for surround and centre channels. Then he wants to channel out LR via pre-out of AVR and into Stereo pre. From stereo pre to Stereo power amp. The CD player shall be connected to Stereo pre-amp and DVD player to the AVR.

Now, when he wants to run CD player, the AVR could be turned off.
When he is using the DVD player then he needs to use AVR (For centre and surrounds) and Stereo Pre & Power for front LR.

Balancing the Volume b/w AVR and stereo Pre could be tricky. One will have to use both remotes- AVR and Stereo Pre for perfect volume control. I don't think it is going to be easy.

This is how I feel it would be done. However, these are my assumptions- All theory. I could be wrong here. If there are other people having different views then I am all ears.

Option 2: Another alternative is probably to use a switcher. The LR speakers shall be connected to the output of the switcher and both- the AVR and Stere Pre shall be connected to the input/s of the switcher. In this the pre-out of AVR is not used-Regular LR speaker connections are used using speaker wire.
One has to toggle inputs from the switcher for desired source.
But, purists condem the use of switcher. They say that it deteriorates the quality of sound. It's your call.

lemme know what u think.
Sumit.

This is absolutely fine.



Do not try or connect this way. Already you will be getting variable output from your AVR's Preout and again you are trying to route this variable output to a Stereo Pre's (Video input) and this signal level is again controlled by the Stereo Pre's volume control which is totally incorrect. It is like trying to connect 2 preamps in series for one Stereo Power Amplifier

This is the right method ....
1) Use a Coaxial cable or an Optical cable from the DVD player to the AVR for Centre channel, Surrounds & Subwoofer.
2) Use a 2 RCA cable and connect the AVR's Front speakers analog preout to a Stereo Power Amp and not to a Stereo Preamp or a Stereo Integrated Amp.
3) Ensure that the wattage of the Stereo Power Amp is equal to AVR's front channels wattage as per AVR's specs.

Cheers,
Ramesh

 

[marsilians]

Basic rule of thumb for variance and distortion in sound output is to increase the no. of paths from source (CD, DVD, AVR) to speakers.

flanker.r and Sumit have the right suggestions. Now if I were you, the simplest I would do is as follows assuming your AVR is multi-channel,

All sources - CD, DVD, STB, MP3 player -> AVR using toslink or coax or analog.

AVR -> stereo power amp (analog cables also called RCA) (from pre-out on your AVR -> RCA in on your amp.

l/R speakers to L/R on Stereo power amp

C/SL/SR speakers to your AVR.

This will ensure there is additional power for the above 3 and you should hear better soundstage and volume levels.

Re: setting volume controls, its best to have the volumes on your sources set to maximum (CD/DVD, etc.) If you are using pre-pro adjust the volume at that location or at an AVR and not at the power amp. Good rule of thumb ro remember this is to adjust volume on the device which is doing the Digital Signal Processing (DSP).

Leave the power amp volume at its highest since its not doing any processing, its just amplifies the sound.

The con to this setup is that your AVR has to be on at all times for audio. This is OK for stereo listening since your center/surrounds wont be getting any input anyways.

 

[silentsound]

Hello Sumit,

I prefer the 1st option where I don't have to use a switch. To manage the volume issue between the pre-amp and avr I'm thinking of setting the pre-amp's volume at a fixed level so that the fronts match the level of centre and surround speakers. This need to be done using a SPL meter and the front speaker level setting in the avr.

Whenever I need to watch a movie I need to set the volume at the pre-fixed level in the pre-amp. (This is what one other member also suggested).

SilentSound.

 

[silentsound]

Hi marsilians,

Thanks for your comments.

Now if I were you, the simplest I would do is as follows assuming your AVR is multi-channel.

My AVR is a 7.1 channel THX Select Yamaha receiver rated at 120 W RMS.

All sources - CD, DVD, STB, MP3 player -> AVR using toslink or coax.

AVR -> stereo power amp (analog cables also called RCA) (from pre-out on your AVR -> RCA in on your amp.

l/R speakers to L/R on Stereo power amp

C/SL/SR speakers to your AVR.

This is exactly how I used to have my components connected.

When I got hold of a used NAD pre-amp I just wanted to see the sound effect of connecting my CD player to the pre-amp instead of the AVR. I couldn't believe the difference. The soundstage was much wider than before. One more improvement is clarity at low volume levels. I don't listen at very high volume so I like the clarity. I don't think I would go back and connect my cd player to the AVR.

SilentSound.

 

[marsilians]

Its good to hear you like the pre-amp's processing. I use them myself and would not go back to a receiver though I feel that you have to carefully match with the power amp and speakers to get the "right mix" Otherwise I have heard some doing a terrible job than a receiver.

A receiver is a sort of jack of all trades while pre-amps do few things and very well.

If you put down the NAD model no., I can maybe take a look at this connections and suggest a different setup if thats the way you want to go.

Now I am curious, why do you still need to keep the AVR if the pre- is doing its job?

 

[silentsound]

Hi marsilians,

My pre-amp is NAD - 1240 and the power amp is NAD-2400. After hearing the difference I'm itching to get a better pre and power though.

I need the AVR for movies. I've my centre, sub and 4 surrounds connected the AVR.

This way for music I need to use only the cdp, pre and the power amp.

For movies I need the dvd player and the AVR in addition to the pre and the power amp.

SilentSound.

 

[Sumit]

Marsilians> You are asking SS to connect all sources including CDP to be connected to the AVR. Hence, the processing shall be done by AVR. This means that the stereo pre-amp is ruled out of the equation!!

I suggest to connect like this;
AVR>Stereo Pre-Amp>Stereo Power Amp>Speakers

When u are watching a movie then u will have fix volume on the Stereo Pre-Amp and vary the volume from the AVR. When u shall use the CDP then u may shutdown the AVR.

Let me know what u think.

PS> I have a attached a diagram for your reference.
Sumit

Basic rule of thumb for variance and distortion in sound output is to increase the no. of paths from source (CD, DVD, AVR) to speakers.

flanker.r and Sumit have the right suggestions. Now if I were you, the simplest I would do is as follows assuming your AVR is multi-channel,

All sources - CD, DVD, STB, MP3 player -> AVR using toslink or coax or analog.

AVR -> stereo power amp (analog cables also called RCA) (from pre-out on your AVR -> RCA in on your amp.

l/R speakers to L/R on Stereo power amp

C/SL/SR speakers to your AVR.

This will ensure there is additional power for the above 3 and you should hear better soundstage and volume levels.

Re: setting volume controls, its best to have the volumes on your sources set to maximum (CD/DVD, etc.) If you are using pre-pro adjust the volume at that location or at an AVR and not at the power amp. Good rule of thumb ro remember this is to adjust volume on the device which is doing the Digital Signal Processing (DSP).

Leave the power amp volume at its highest since its not doing any processing, its just amplifies the sound.

The con to this setup is that your AVR has to be on at all times for audio. This is OK for stereo listening since your center/surrounds wont be getting any input anyways.

 

[flanker.r]

I have seen a lot of AV Receivers converting analog to digital and do the processing (even the volume adjustment) in digital domain and then convert to analog. Does your AV receiver do that?

If it does you are essentially converting digital signal in dvd/cd to analog (if you use RCA and take the pre-outs) converting it back to digital, apply volume processing, convert to analog, feed it to stereo receiver, re-process in analog domain and amplify. Losses in signal chain, losses in format conversion, etc

you are right. you will get better performance when you go for a better pre-power combo as the pre and power are quite old. the 2400 utilises power envelope and EDP that basically inverts the power supply to the 2 channels. Thankfully, NAD abandoned that approach in later models with good reason

Keep the stereo isolated from the AV section . you will definitely have better results. Yes, a speaker switch/selector is not the purists way of doing things but it definitely a lot better than routing sources through a AV receiver

 

[silentsound]

Hi flanker,

Thanks. I'm not sure how my avr apply volume adjustment to analog signals. But in my case the only time I'm using my avr is when I'm watching movies. My dvd player is connected to the avr using a coaxil cable which is a digital signal. Do I still need to worry about the signal loss you have mentioned.

I know the pre and the power are pretty old and I got them only for my second setup. When I tried with my main setup I realized the difference between the stereo amp and the avr. My next task is to save money for a good pre/power combo or a good integrated amp.

Thanks again for your comments.

Cheers,
SilentSound.

 

[marsilians]

Ok Silent Sound/Sumit

I saw the diagram. Thatas a very workable model. There are 2 things that you need to keep note of and you have to make a decision on yourself.

1. The Digital Signal Processing in your Pre-Amp shoudl be >= AVR if you want good clarity when watching movies.

2. YOu will not have the centre channel for music (some DSPs do sound better if you have the right source).

If you are always happy with 2 channel listening without a sub then you are good to go.

 

[silentsound]

Hi marsilians,

1. The Digital Signal Processing in your Pre-Amp shoudl be >= AVR if you want good clarity when watching movies.

I'm not sure I understood this correctly. But the connection from my avr to stereo is analog connection. Its from the avr pre-out to pre-amp input thru rca cables. Where is the need for digital signal processing. As I said may be I'm not understanding this correctly.

2. YOu will not have the centre channel for music (some DSPs do sound better if you have the right source).

I don't want this but If I needed it I could still play the cd thru my dvd player and get the various dsp effects.

If you are always happy with 2 channel listening without a sub then you are good to go.

Even for this, if I needed additional bass I could always connect my sub to the second pre-out of the pre-amp. I could set the avr to send the lfe signals to the fronts instead of the sub.

Hope this makes sense.

Cheers,
SilentSound.