No pre out on AVR, can I use headphone socket to connect to power amp?

[Jason101]

Hi,

I have a Sony str-dh790 receiver with no pre out.

I have bought a used pair of hard to drive speakers with low sensitivity, kef reference 201/2.

I would like to experiment by running the speakers with a Cown Xli1500.

Can I use the headphone socket on the front of the Sony receiver to connect into the Crown amplifier RCA inputs using a 6.35mm 1/4 inch male TRS stereo plug to 2x RCA male audio Y Splitter order to listen to stereo music via the Crown amplifier?

The Crown amplifier has a switch to accept either an input sensitivity of 0.755V or 1.4V via the RCA input.

Would this work and how would the volt output from the headphone socket compare to the volts requirements of the Crown RCA inputs?

If the speakers sound much better with the Crown power amp, then I will look for a more permanent solution.
My source to the Sony AVR amp is via hdmi Chromecast lossless Deezer from mobile device.

Thanks

 

[staticV3]

Hi @Jason101! Welcome to ASR.

Can I use the headphone socket on the front of the Sony receiver to connect into the Crown amplifier RCA inputs using a 6.35mm 1/4 inch male TRS stereo plug to 2x RCA male audio Y Splitter order to listen to stereo music via the Crown amplifier?

Yes. May not be optimal, but it'll work.

Would this work and how would the volt output from the headphone socket compare to the volts requirements of the Crown RCA inputs?

Sony do not specify the output voltage of the DH790's headphone output.

If you're curious, a basic $15 multimeter is all you need to measure output voltage yourself.

 

[Jason101]

Hi staticV3,

Thanks for the welcome and your reply.

That's fantastic, I'll use this non optimal (& non expensive) method to try out the speakers with a more powerful amp.

If I like the results then I'll know it's worth upgrading the AV to one with pre amps, maybe a rotel or anthem.
I'll try the multinmetre too.
I just didn't want to do anything silly like damaging the amp or speakers.
Thanks

 

[mhardy6647]

Yes. May not be optimal, but it'll work.

yup.

As to which sensitivity to pick on the Crown -- I'd try both and see which works better.
I'd probably start with the higher voltage level input for the amp and, if volume is inadequate, switch to the other level.
Just be cautious with levels, especially to start -- out of deference to your loudspeakers.

 

[eeMGee]

Hi,

I have a Sony str-dh790 receiver with no pre out.

I have bought a used pair of hard to drive speakers with low sensitivity, kef reference 201/2.

I would like to experiment by running the speakers with a Cown Xli1500.

Can I use the headphone socket on the front of the Sony receiver to connect into the Crown amplifier RCA inputs using a 6.35mm 1/4 inch male TRS stereo plug to 2x RCA male audio Y Splitter order to listen to stereo music via the Crown amplifier?

The Crown amplifier has a switch to accept either an input sensitivity of 0.755V or 1.4V via the RCA input.

Would this work and how would the volt output from the headphone socket compare to the volts requirements of the Crown RCA inputs?

If the speakers sound much better with the Crown power amp, then I will look for a more permanent solution.
My source to the Sony AVR amp is via hdmi Chromecast lossless Deezer from mobile device.

Thanks

I would not recommend it - AVR has got headphone socket connected via two 330 Ohm resistors in series (660 Ohm in total) directly from power amps outputs, so when it has output power about 100 W/6 ohm you can expect about 25 Vrms or 35 Vp on the RCA input connector of the Crown amp (input impedance is 10k) with AVR volume on max.
So be careful with volume control to not overload it...

When you plug the headphones with impedance from 32 - 120 Ohm into the headphone socket it will make voltage divider with the 660 ohm resistance so it will give you from about 1,2 Vrms to 3,8 Vrms for the headphones max., so it is safe for them. Most AVRs use this cheap connection to the headphone socket via serial resistor only (470 - 1k).

Edit: You can put 100 Ohm resistor in paralell to the input impedance of the Crown amp, but it requires some DIY.

 

[DVDdoug]

Edit: You can put 100 Ohm resistor in paralell to the input impedance of the Crown amp, but it requires some DIY.

If you're going to do that, you might as well add another resistor (4 resistors total) and make your own voltage dividers to connect to the speaker outputs on the back. (Resistors that add-up to around 5K should keep the power low-enough that you don't burn-up the resistors.)

You can also buy speaker-to-line-level converters.

 

[Jason101]

Thank you eeMGee and DVDdoug

I didn't realise this about the headphone jack. That sounds like one risk too many with my beloved and rare speakers.

I think I would feel much safer to buy a speaker-to-line-level converter, as you have suggested.

I haven't found any hifi rated ones in or offering shipment to the UK.

The only one I can find that states for Hifi use (rather than car/auto audio) is the Russound ADP-1.2. But not available here. The Russound is rated for Hifi and rated up to 200w
Where as the ones I can find here are for auto car stereos and are rated at 40w and not recommended for hifi.
I don't know if I can use them on hifi?

Just a thought, the Crown's input sensitivity is a selectable input sensitivity. There is a 1.4Vrms and .775Vrms option.
I was wondering if that had any impact on hooking it up via the headphone jack or as to which Speaker-level to Line-level Adapter to use?

 

[Roland68]

Hi,

I have a Sony str-dh790 receiver with no pre out.

I have bought a used pair of hard to drive speakers with low sensitivity, kef reference 201/2.

I would like to experiment by running the speakers with a Cown Xli1500.

Can I use the headphone socket on the front of the Sony receiver to connect into the Crown amplifier RCA inputs using a 6.35mm 1/4 inch male TRS stereo plug to 2x RCA male audio Y Splitter order to listen to stereo music via the Crown amplifier?

The Crown amplifier has a switch to accept either an input sensitivity of 0.755V or 1.4V via the RCA input.

Would this work and how would the volt output from the headphone socket compare to the volts requirements of the Crown RCA inputs?

If the speakers sound much better with the Crown power amp, then I will look for a more permanent solution.
My source to the Sony AVR amp is via hdmi Chromecast lossless Deezer from mobile device.

Thanks

You can buy a used Yamaha RX-V779 without Atmos, RX-V781 or RX-A850 - 880 with Atmos. All with preamp outputs for all channels, so can also be used as a complete preamp. Approx. €200-400.

 

[Jason101]

You can buy a used Yamaha RX-V779 without Atmos, RX-V781 or RX-A850 - 880 with Atmos. All with preamp outputs for all channels, so can also be used as a complete preamp. Approx £200-400.

Thanks, but at this stage I'm not after a permanent solution. As I've recently acquired a pair of Kef Reference 201/2 speakers and I'm yet to decide if I'm going to keep them.

So far I've only run them on my budget Sony AV, the Sony str-dh790
And I would need to hear them with a load more watts before making an informed choice.

I think the cheapest and easiest way would be to use my AV as a pre amp to the Crown power amp via the headphone jack OR a Speaker-level to Line-level Adapter to use.

And I just need some advice, as my previous post.

If I'm going to keep the speakers, then I'll look for a more permanent solution

Cheers.

 

[eeMGee]

This adapter should work:

https://www.amazon.co.uk/dp/B08G883DVQ

 

[Hayabusa]

If you're going to do that, you might as well add another resistor (4 resistors total) and make your own voltage dividers to connect to the speaker outputs on the back. (Resistors that add-up to around 5K should keep the power low-enough that you don't burn-up the resistors.)

You can also buy speaker-to-line-level converters.

You should make sure then that the min speaker pole is really ground

 

[Philbo King]

If the AVR is old enough to have a Tape Out (Rec), it would be the ideal solution.

 

[Bruce Morgen]

If the AVR is old enough to have a Tape Out (Rec), it would be the ideal solution.

That would be before the AVR's volume control circuit in its internal signal chain -- IOW, you'd have to control volume via some other means, e.g. the power amp's volume/level control if it has one.

 

[Hayabusa]

You should make sure then that the min speaker pole is really ground

Extra: I see the crown has XLR in, so even in the case the output of the sony is balanced you can make a balanced attenuation resistor network:

some thing like this (R1 is not needed)

I would go for 20dB attenuation: R2 = 1k(1watt) (for balanced 2x500ohm (1/2 watt) R3 100ohm (1/8watt)

 

[eeMGee]

For your headphone socket this can be used:

https://www.amazon.co.uk/Stageline-21-2840-Passive-Level-Attenuator/dp/B0057G44WM

and

https://www.amazon.co.uk/Pro-Signal-SIGNAL-PSG00179-6-35mm/dp/B0B23R6C2S

or any other 6,35 mm jack to RCA cable.

 

[Jason101]

Extra: I see the crown has XLR in, so even in the case the output of the sony is balanced you can make a balanced attenuation resistor network:

some thing like this (R1 is not needed)

View attachment 384330

I would go for 20dB attenuation: R2 = 1k(1watt) (for balanced 2x500ohm (1/2 watt) R3 100ohm (1/8watt)

I think a diy solution may be beyond my skill and time availability to learn at moment with a young family. But I bet it be perfect for anyone else finding this thread in the future.
Also the 20dB attenuation information is great to go alongside eeMGee's suggested headphone socket attenuator.

 

[Jason101]

I did have a couple of other thoughts on solving this problem.
(Crown amp arriving tomorrow).

I was wondering if I could use an HDMI to RCA converter?

I have seen some that have an hdmi input on one side and on the other side have rca outs for stereo and an hdmi out for vision (vision only, I think?).

I don't know the output signal rating on the rca's.
I'm wondering its possible to plug the converter into the AV's hdmi out, then plug an hdmi cable from the converter to the TV and the rca out from the converter into the Crown amp and leave in situe to listen to stereo music as well as watch movies in 5.1 surround sound both via the Crown amp?

https://amzn.eu/d/82cjghQ

The other, probably daft thought I had was the receiver has 2x sub outs. One I'm sing for a sub. I was wondering if they are full range and if I can use the other sub out as a pre out?

 

[Jason101]

Bump