Adding a 2nd output ?

q · 17328

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Offline q

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on: November 06, 2009, 11:13:35 AM
Can I add another output?(like my Foreplay3) and what do I need to be careful of
thx again
q


Offline Koda

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Reply #1 on: November 12, 2009, 12:06:42 PM
I was wondering that same thing, the "Y" splitter I use for a sub input is most likely not the best way to go.
Since the FP3 uses dual outputs, perhaps the same kind of thing can be done to the Quickie?
Hopefully someone that has built a FP3 can offer some words of wisdom on how to add another output  with minimal sonic damage.
  Thanks, K.

Kevin Erickson

Offline Grainger49

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Reply #2 on: November 12, 2009, 01:44:43 PM
Q

Adding another speaker output is easy.  Just parallel them with the existing outputs.

The trick is if you want to play both of the speakers at the same time.  That changes the impedance of the connected load and should require you to change the output tap on the transformer.

So the answer is yes, and no.  No, if you want to play two 8 ohm speakers at the same time, you should change the output transformer tap.  Of you want to play a 4 ohm speaker and an 8 ohm speaker at the same time, it is not advisable.  And, yes, you can parallel the outputs.

Confused yet?

Edit:

Ok, I see what you mean.  As PJ suggests a series resistor with the hot lead to the second output would give you less interaction between the two.  The high impedance of the amplifier's inputs really helps.
« Last Edit: November 12, 2009, 03:24:05 PM by Grainger49 »


Offline Koda

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Reply #3 on: November 12, 2009, 02:06:53 PM
Confused? Sort of...
I want to use the Quickie as a standard preamp to drive both my main and sub amps, so I do not have a transformer.
Can I just parallel the two output jacks, or do I need to isolate them somehow so they do not "interact" with each other?
  Sorry if I was not being clear.
      Thanks, K.

Kevin Erickson

Offline Paul Joppa

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Reply #4 on: November 12, 2009, 02:24:13 PM
It's thought to be "good practice" to put a resistor between them, so the main output is direct and the secondary one has the resistor. We use 1K in the Foreplay. I don't think it's terribly important though - the serious interaction problems are quite unlikely, and a resistor big enough to really eliminate them will be far too large to drive a normal cable.

Paul Joppa

Offline q

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Reply #5 on: November 13, 2009, 09:43:23 AM
Quote from: Paul Joppa on November 12, 2009, 02:24:13 PM
It's thought to be "good practice" to put a resistor between them, so the main output is direct and the secondary one has the resistor. We use 1K in the Foreplay. I don't think it's terribly important though - the serious interaction problems are quite unlikely, and a resistor big enough to really eliminate them will be far too large to drive a normal cable.

Cool
I was going to benchmark my ForeplayIII's output and apply to the Quickie
Same Resistor value etc??
thanks you guys
q


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