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Speaker Level to Line Level Converter

post #1 of 15
Thread Starter 
Has anyone here tried using a speaker level to line level converter, specifically in those receivers without preouts? Here's one for example:

http://www.crutchfield.com/S-IV8trDi...aspx?i=127OEM2

Seemingly you could use this to add an amp to your AVR that doesn't have preouts on it. Or am I totally getting this wrong.
post #2 of 15
Yup. Basically, two resistors per channel.
post #3 of 15
Thread Starter 
Quote:
Originally Posted by Kal Rubinson View Post

Yup. Basically, two resistors per channel.

Oh cool! So basically now I can turn my receiver without preouts to one with preouts for only $30. Excellent.
post #4 of 15
Note there is a 60 watt / channel limit on it. I assume that's due to the resistor's power handling capability.
post #5 of 15
Quote:
Originally Posted by MichaelJHuman View Post

Note there is a 60 watt / channel limit on it. I assume that's due to the resistor's power handling capability.

Yup. Gotta dissipate the heat.
post #6 of 15
Thread Starter 
Hmmm...maybe this would work. But it looks kinda bare and open.

http://www.crutchfield.com/S-mFQywdu...spx?I=543ADP12
post #7 of 15
Quote:
Originally Posted by pcdo View Post

Hmmm...maybe this would work. But it looks kinda bare and open.

http://www.crutchfield.com/S-mFQywdu...spx?I=543ADP12

Yup. $1 worth of resistors and $2 worth of connectors.
post #8 of 15
Quote:
Originally Posted by Kal Rubinson View Post

Yup. $1 worth of resistors and $2 worth of connectors.

I was just going to post a topic asking about this. Specifically, what is the value of resistance I should use if I wanted to build wunna-dis-tings?
post #9 of 15
Quote:
Originally Posted by Mr. Hanky View Post

I was just going to post a topic asking about this. Specifically, what is the value of resistance I should use if I wanted to build wunna-dis-tings?

Google "speaker to line schematic" or "speaker to line circuit." Here's a start: http://www.epanorama.net/circuits/speaker_to_line.html
post #10 of 15
Ok, thanks! I will check it out.
post #11 of 15
Quote:
Originally Posted by pcdo View Post

Oh cool! So basically now I can turn my receiver without preouts to one with preouts for only $30. Excellent.


Ummm, yeah it sorta gets you a set of preouts, in a Rube Goldberg kind of way. But it's not really the same thing as a actual preout from a AVR that actually has them or the output from a pre-pro/pre-amp.

All you are really doing is clamping down on the speaker outputs from the receivers own amps by running it through some resistors, to drop it's power output down to a level where it will not overload feeding a power amp.

Probably not the best thing in the world as far as keeping a audio signal as clean and unmolested as possible, but I guess if all you are looking for is a very cheap way to add a bigger power amp to a AVR without a set of preouts, it's also probably about the lowest cost way to do it without buying a new AVR.
post #12 of 15
Quote:
Originally Posted by Johnla View Post

Ummm, yeah it sorta gets you a set of preouts, in a Rube Goldberg kind of way. But it's not really the same thing as a actual preout from a AVR that actually has them or the output from a pre-pro/pre-amp.

All you are really doing is clamping down on the speaker outputs from the receivers own amps by running it through some resistors, to drop it's power output down to a level where it will not overload feeding a power amp.

Probably not the best thing in the world as far as keeping a audio signal as clean and unmolested as possible, but I guess if all you are looking for is a very cheap way to add a bigger power amp to a AVR without a set of preouts, it's also probably about the lowest cost way to do it without buying a new AVR.

Agreed. It will work reliably but, if the user is trying to avoid using the built-in power amps, it is not ideal.
post #13 of 15
Quote:
Originally Posted by Johnla View Post

Ummm, yeah it sorta gets you a set of preouts, in a Rube Goldberg kind of way.

You understate old Rube's good work. ;-)

This is not nearly as arcane or inefficient as Rube's fertile imagination.

Quote:


But it's not really the same thing as a actual preout from a AVR that actually has them or the output from a pre-pro/pre-amp.

Agreed, but it may be closer than you think.

Quote:


All you are really doing is clamping down on the speaker outputs from the receivers own amps by running it through some resistors, to drop it's power output down to a level where it will not overload feeding a power amp.

It's not clamping, it is tapping down. It is as benign as a volume control.

It has the secondary effect of operating the receiver's own amps into a more linear mode of operation than driving speakers.

For example, most receiver power amps will stay out of class-AB operation and be running pure class A. Bass extension can also improve.

The receiver's power supply will usually truely be loafing.

The benefits over just a larger receiver are many. Far less heat, far lighter, and possibly smaller. Paves the way to system refinements involving equalizers, electronic crossovers, etc.

Quote:


Probably not the best thing in the world as far as keeping a audio signal as clean and unmolested as possible, but I guess if all you are looking for is a very cheap way to add a bigger power amp to a AVR without a set of preouts, it's also probably about the lowest cost way to do it without buying a new AVR.

Exactly. But a good power amp is also just a big op amp. Sort of like the output stage of a good preamp on steroids.
post #14 of 15
And I'd wager to say that anyone who does something like this to a lower cost AVR without a set of preouts, is only doing so in order to hook up a more powerful external power amplifier to it to get a louder volume output for as cheap as possible. Yeah you have some basis behind your theories/claims, but these so called "system refinements" you mention are at best questionable when applied to a lower cost budget AVR, and are not what these kind of people are aiming for, what they want louder or more power for hard to drive speakers. I also doubt that many, if any, would notice any real improved bass extension at all with doing this. And that any improvements they will notice at all, will come solely from the larger and more powerful external power amps that they added.
post #15 of 15
How would tapping into the headphone output work? There isn't much power coming from that. Might be worth a try.

Whats the power requirements of a good set of phones?
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