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Quote:
Originally Posted by Kal Rubinson /forum/post/14946977


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.
 

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

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Quote:
Originally Posted by MichaelJHuman /forum/post/14947328


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.
 

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Quote:
Originally Posted by Kal Rubinson /forum/post/14949111


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?
 

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Quote:
Originally Posted by Mr. Hanky /forum/post/15293221


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
 

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Ok, thanks! I will check it out.
 

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Quote:
Originally Posted by pcdo /forum/post/14947167


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.
 

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Quote:
Originally Posted by Johnla /forum/post/15299981


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.
 

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Quote:
Originally Posted by Johnla /forum/post/15299981


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.
 

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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.
 

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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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Quote:Originally Posted by Johnla

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.
Hmm..

So, what about using one of these to attach a powered/active sub without high level inputs to a 2 channel amp without a pre-amp output?

Would putting one of these resistive devices on the same amp outputs as the left and right speakers cause any wacky impedance crap going on, or should it work pretty well, much as if the sub had its own built in high level input?
 

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Hmm..

So, what about using one of these to attach a powered/active sub without high level inputs to a 2 channel amp without a pre-amp output?

Would putting one of these resistive devices on the same amp outputs as the left and right speakers cause any wacky impedance crap going on, or should it work pretty well, much as if the sub had its own built in high level input?
Quote:Originally Posted by Johnla

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.


Well, there is always this for the person who doesn't want to deal with an external converter...

https://www.monoprice.com/product?c_id=109&cp_id=10918&cs_id=1091806&p_id=11497&seq=1&format=2

An amp with a built in converter. I always wondered how good these amps are though...
 

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No name, pig in a poke. Also, I am guessing that it uses the same type of resistor-based voltage already discussed.
This should work.When I had my Sony Rx I looked into this before I ended up just getting an Onkyo TX-NR838 with Preouts
BEHRINGER ULTRA-DI PRO DI800 *Allows direct connection to speaker outputs with up to 3,000 Watts*

Professional Mains/Phantom Powered 8-Channel DI-Box

  • Professional and multi-purpose 8-channel direct injection box for stage and studio applications
  • Provides impedance and signal matching for the direct connection of instruments to mixers and amplifiers
  • Ultra-flat frequency response due to servo-balanced operation
  • Optional mains or phantom-powered operation
  • Allows direct connection to speaker outputs with up to 3,000 Watts
  • +20 dB gain switch for pre-amplification of low-level signals
  • Switchable input attenuation allows input levels of up to +40 dB
  • Ground Lift switch eliminates typical ground loop problems
  • Link output for easy connection to further equipment
  • 1/4" TRS and gold-plated XLR connectors
  • Illuminated switches for secure operation in dark stage environments
  • Shielded toroidal mains transformer for minimal noise interference
  • High-quality components and exceptionally rugged construction ensure long life
 

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This should work.When I had my Sony Rx I looked into this before I ended up just getting an Onkyo TX-NR838 with Preouts
BEHRINGER ULTRA-DI PRO DI800 *Allows direct connection to speaker outputs with up to 3,000 Watts*

Professional Mains/Phantom Powered 8-Channel DI-Box

  • Professional and multi-purpose 8-channel direct injection box for stage and studio applications
  • Provides impedance and signal matching for the direct connection of instruments to mixers and amplifiers
  • Ultra-flat frequency response due to servo-balanced operation
  • Optional mains or phantom-powered operation
  • Allows direct connection to speaker outputs with up to 3,000 Watts
  • +20 dB gain switch for pre-amplification of low-level signals
  • Switchable input attenuation allows input levels of up to +40 dB
  • Ground Lift switch eliminates typical ground loop problems
  • Link output for easy connection to further equipment
  • 1/4" TRS and gold-plated XLR connectors
  • Illuminated switches for secure operation in dark stage environments
  • Shielded toroidal mains transformer for minimal noise interference
  • High-quality components and exceptionally rugged construction ensure long life
Its $120.00 on all of the sites.not to expensive
 
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