Audio Transformer ... How?

[Ext User(nimbiotics@gmail.com)]

First I want to apologize for my poor english. I'm not english
speaker.

For space sake, I will describe my situation giving only details I
think are strictly necessary. If you need any more details please
don't hesitate to ask.

I've got an amplified signal from a 40watts stereo amplifier. I need
to feed this to a device that will only receive preamplified signal.
I can control the output of this amplifier with high accuracy in up to
+65500 increments so I was thinking about using this feature. The only
issue was to determine my top value.
I was told by a friend that I should use a 1:1 audio transformer and
start testing for saturation (basically by monitoring the output, no
hitech involved here, dont have the knowledge)

I searched the net for the audio transformer and I am now more
confused than when I started. I wouldn't even know how to hook up the
transformer so I will definetly need help on that to. Do I have to use
one transformer per channel? How am i suposed to wire it? How am I to
know what my max volume level should be on my amplifier?

Any and all comments will be highly appreciated.

Muchas Gracias in advanced
Mario Osorio

[Ext User(Stuart)]

<nimbiotics@gmail.com> wrote in message
news:1173652616.625080.323530@64g2000cwx.googlegro ups.com...
> First I want to apologize for my poor english. I'm not english
> speaker.
>
> For space sake, I will describe my situation giving only details I
> think are strictly necessary. If you need any more details please
> don't hesitate to ask.
>
> I've got an amplified signal from a 40watts stereo amplifier. I need
> to feed this to a device that will only receive preamplified signal.
> I can control the output of this amplifier with high accuracy in up to
> +65500 increments so I was thinking about using this feature. The only
> issue was to determine my top value.
> I was told by a friend that I should use a 1:1 audio transformer and
> start testing for saturation (basically by monitoring the output, no
> hitech involved here, dont have the knowledge)
>
> I searched the net for the audio transformer and I am now more
> confused than when I started. I wouldn't even know how to hook up the
> transformer so I will definetly need help on that to. Do I have to use
> one transformer per channel? How am i suposed to wire it? How am I to
> know what my max volume level should be on my amplifier?
>
> Any and all comments will be highly appreciated.
>
> Muchas Gracias in advanced
> Mario Osorio
>


Quote: "I've got an amplified signal from a 40watts stereo amplifier. I need
to feed this to a device that will only receive preamplified signal."


It is not considered good electronic practise to connect a power amplifier
(your 40 watt amp) to a pre-amp for a number of reasons. However there are
situations when this is the only possibility.

So the way to do it is to isolate the power amp from the pre-amp or
transform a power device from an electrical device (per-amp)

The way to do this is either with a step down transformer or more simply
with a resistive network or attenuator. Probably a 20db pad would do - if
this email survives formatting it would look like this

amp output xxxxxxxxx-xxxxxxxxx to pre-amp input
x
x
x
x

Where the network looks like a T with a resistor either side of the junction
and the base of the vertical connected to earth.


Look up on google " 20db pad from speaker output to line in"
http://www.whirlwindusa.com/dirbox.html

[Ext User(Richard Crowley)]

<nimbiotics@gmail.com> wrote ...
> I've got an amplified signal from a 40watts stereo amplifier. I need
> to feed this to a device that will only receive preamplified signal.

You can use one of the attenuators that the car audio
installers use to take power amplifier outputs and feed
into line-level inputs. Like these...
http://www.partsexpress.com/webpage.cfm?webpage_id=3&CATID=35&ObjectGroup_ID=743
They call them "High/Low Adapters"

Or you could make your own with a few resistors for
less than it costs you to buy a cup of coffee.

[Ext User(Stuart)]

"Richard Crowley" <rcrowley@xpr7t.net> wrote in message
news:12v98ac1us1kv9c@corp.supernews.com...
> <nimbiotics@gmail.com> wrote ...
>> I've got an amplified signal from a 40watts stereo amplifier. I need
>> to feed this to a device that will only receive preamplified signal.
>
> You can use one of the attenuators that the car audio
> installers use to take power amplifier outputs and feed
> into line-level inputs. Like these...
> http://www.partsexpress.com/webpage.cfm?webpage_id=3&CATID=35&ObjectGroup_ID=743
> They call them "High/Low Adapters"
>
> Or you could make your own with a few resistors for
> less than it costs you to buy a cup of coffee.
>
>

Forgot about those - I remember I set up a system for a friend years ago and
found one of these adapters at Strathfield Car Radios for $5 - good one a
lot cheaper than DI boxes

[Ext User(GregS)]

In article <1173652616.625080.323530@64g2000cwx.googlegroups.c om>, nimbiotics@gmail.com wrote:
>First I want to apologize for my poor english. I'm not english
>speaker.
>
>For space sake, I will describe my situation giving only details I
>think are strictly necessary. If you need any more details please
>don't hesitate to ask.
>
>I've got an amplified signal from a 40watts stereo amplifier. I need
>to feed this to a device that will only receive preamplified signal.
>I can control the output of this amplifier with high accuracy in up to
>+65500 increments so I was thinking about using this feature. The only
>issue was to determine my top value.
>I was told by a friend that I should use a 1:1 audio transformer and
>start testing for saturation (basically by monitoring the output, no
>hitech involved here, dont have the knowledge)
>
>I searched the net for the audio transformer and I am now more
>confused than when I started. I wouldn't even know how to hook up the
>transformer so I will definetly need help on that to. Do I have to use
>one transformer per channel? How am i suposed to wire it? How am I to
>know what my max volume level should be on my amplifier?
>
>Any and all comments will be highly appreciat

Radio Shack has a type of audio isolation transformer that should work well
with some sort of attenuator out of the amplifier. These isolators are frequently used in car audio
and anytime you want to isolate hum and other things.

greg

[Ext User(nimbiotics@gmail.com)]

Thanks a lot for your answer

[Ext User(nimbiotics@gmail.com)]

Thanks a lot for your answer

[Ext User(Geoff)]

nimbiotics@gmail.com wrote:
> Thanks a lot for your answer

That's two lots !

geoff

[Ext User(nimbiotics@gmail.com)]

Guess u r rite. Make it 3 lots...

Mario Osorio

[Ext User(Keith G)]

<nimbiotics@gmail.com> wrote in message
news:1174316124.176038.231720@e1g2000hsg.googlegro ups.com...
> Guess u r rite. Make it 3 lots...
>
> Mario Osorio



Thank you for removing ukra from your future posts....

;-)