Line level converter for temporary home AV set-up

[Mxplut]

Hello
Word from Father Christmas is that I have been good enough to deserve a Cambridge x201 subwoofer but not good enough for a new AV amp. That will need to come later in the year when the price of the 2020 models starts dropping

This means that I need to keep using my old JVC integrated unit that only has speaker outs. The sub only has line level inputs. My question is whether it will work to link my speakers to the JVC speaker outs and in parallel connect a line level converter to get a signal to the sub.

surely not ideal, but the alternative is keeping my existing set up and having my new toys gather dust until I can afford the new AV amp. But would it work?

thanks
Ben

 

[rothwellaudio]

Yes, it would work. You need to drop the voltage at the speaker outputs by about 30dB (which is about the same gain as the power amp in the JVC has).

 

[century tek]

If that is a powered sub, the left and right line level inputs would be taken either from the JVC's rec out jacks or pre out jacks (if this model has them).

 

[rothwellaudio]

If that is a powered sub, the left and right line level inputs would be taken either from the JVC's rec out jacks or pre out jacks (if this model has them).

"Rec out" would give a fixed signal level not controlled by the amp's volume control.

 

[Mxplut]

Thank you. My JVC system is a MXS-4 from around 1993. Unfortunately it only has speaker out and headphone out but it sounds like I’ll be ok for a while. I suppose the 30db reduction is an adjustment on the converter?

 

[electronjohn]

There's speaker level to line level converters available for car stereo use. One of those might do the trick.

 

[twiiii]

Use the head phone output.

 

[century tek]

"Rec out" would give a fixed signal level not controlled by the amp's volume control.

Correct but some people use the rec outs and just leave the sub at one set volume. Soooo many options with these things!

 

[RTally]

Correct but some people use the rec outs and just leave the sub at one set volume. Soooo many options with these things!

Well, that is not a very good option unless one is going to listen at the same volume all the time.

The best option is to feed the subwoofer an input that varies with the speaker volume. That way the sub can be dialed in to blend with the mains and not need to be further adjusted.

If the OP is able to solder connections, a speaker to line converter can be easily made with an interconnect and some resistors. I made one for my home gym system to connect a BOTL internet capable Yamaha receiver to an Adcom amp. The resistor end connects to the speaker output connections and the RCA end plugs into the amp. It works well.The same converter could be used to feed the subwoofer in parallel with the main speakers.

See
https://audiokarma.org/forums/index...bad-the-distortion-is-plus-crazy-idea.831588/
https://www.epanorama.net/circuits/speaker_to_line.html

 

[century tek]

Well, that is not a very good option unless one is going to listen at the same volume all the time.

Yeah, there is absolutely nothing wrong with using this option. People do it all the time. It has been discussed to no end around here! If you don't want to hear the sub when the receiver or amp is turned down, then just simply stop the music.

Sure, the optimum would be to use a pre out but many receivers/amps do not have this option so it is either the speaker outputs to the high level inputs on the sub, or other options to explore.

Guess you haven't been around here long enough to know what I know. Not saying you don't know your stuff, but you would know that this is an option in certain circumstances or even by choice to adjust the sub individually. It is still fine to try.

As said, many different options with powered subs.

 

[RTally]

Guess you haven't been around here long enough to know what I know. Not saying you don't know your stuff, but you would know that this is an option in certain circumstances or even by choice to adjust the sub individually. It is still fine to try.

As said, many different options with powered subs.

I am in awe that you deemed me worthy to respond to.

 

[whoaru99]

Thank you. My JVC system is a MXS-4 from around 1993. Unfortunately it only has speaker out and headphone out but it sounds like I’ll be ok for a while. I suppose the 30db reduction is an adjustment on the converter?

Some are adjustable, but I think it's moreso intended just to give an approximation of the attenuation between the two.

For me a voltage divider of ~10:1 usually works OK. That provides roughly 20dB attenuation of the high level signal to feed to the sub.

 

[cademan]

Hey, not defending either person or persons here but a powered sub can be used in any mentioned configuration depending on what works good for you!

 

[loudnoises]

Running the sub with no control over the level means it's always going to sound imbalanced.

You can try to tell yourself this is a good idea, that others do it and it's cool, but it's not...

 

[coonmanx]

Would connecting it to the headphone jack work? Seriously? Volume controlled and a lower signal to boot. Experts....

twiiii already mentioned this... Is he right?

 

[coonmanx]

When my college roommate went with a line level converter so that he could use his old receiver to power a Carver Cube, it was not a good combination at all. I would look for other options first. But in this case it would only be used to run a sub. Still there has to be a better way than amplifying a signal, attenuating a signal back down and then reamplifying it...

 

[the skipper]

Would connecting it to the headphone jack work? Seriously? Volume controlled and a lower signal to boot. Experts....

twiiii already mentioned this... Is he right?

I believe he is correct and you won't hurt anything by trying it.

This assumes the speakers aren't muted when you plug something into the headphone jack.

 

[whoaru99]

...Still there has to be a better way than amplifying a signal, attenuating a signal back down and then reamplifying it...

Sure, pre outs.

But, those adapter gadgets were developed for cases where that's not a viable option.

Far as the headphone jack, as the skipper mentioned, it can work as long as it doesn't disconnect the speakers. That said, in many cases perhaps most, on a receiver the headphone jack output is just speaker output attenuated in a same/similar manner re. voltage divider.

 

[the skipper]

Still there has to be a better way than amplifying a signal, attenuating a signal back down and then reamplifying it...

There are, but your amp doesn't allow it. Ya gotta work with wacha got.

PS. That's exactly what happens when you feed a powered sub via speaker level inputs.

 

[charles 1973]

Perhaps ask father Christmas for a sub that works with your equipment. That is an expensive sub, and to not include speaker inputs is inexcusable. Even Parts Express subs at a fraction of the price have them. Oh and yes, they really rock too.

That said, if the line level adapter works as well in the house as it worked in my car amp from the stock Delco radio/CD player, It can sound incredible. Even the installer was surprised at how well it worked.