will ppi .2 art amps handle an 8v preout from head unit

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ken - 24 Apr 2004 17:03 GMT

I am going to purchase an Eclipse cd8454 head unit. It has an 8v
preout at 55 ohms and was wondering if a ppi art a600.2 and and
ax606.2 would handle the 8v preout from the head unit. I do realize
the gains would have to be almost all the way down but was wondering
even if the gains were way down would that high of a signal still clip
the amps. also I do have a shematic from ppi to increase the a600.2
input voltage from 2.5v to 8v but it requires putting a 30k resistor
in the left and right input channel. I would prefer not to mess with
amps internal parts if posssible. That is why I would like to know if
it would be possible to handle the 8v input without modifying the amp.

Thanks
Ken

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Daniel Snooks - 26 Apr 2004 03:28 GMT

> I am going to purchase an Eclipse cd8454 head unit. It has an 8v
> preout at 55 ohms and was wondering if a ppi art a600.2 and and
[quoted text clipped - 9 lines]
> Thanks
> Ken

This isn't as big an issue as you might think. The 8v is a rated maximum.
The signal sent to the amp is regulated by the voltage. In other words, when
the volume of the head unit is at full (let's say that is 30) then the amp
is receiving 8v (this varies with the material being played of course).
However, most decks do not operate in a linear fashion, meaning that around
75% volume (23 out of 30) you probably only have about 4v. In your situation
(a 8v head unit mated with a 2.5v amp), you simply will leave the gains on
the amp at minimum, and probably use about 60% volume as the maximum. You
should be able to tell when you are approaching the limits of the amps
inputs long before you overdrive it into clipping.
I am using a RF head unit (4v) and an old Zapco AG200 (2v) right now. I have
noticed that it doesn't matter what the gains on the amp are set at, the
deck starts distorting the signal past 25. So I use 25 as my maximum, and
set the gains on the amp accordingly (about 1/3 for now).
Hope any of that makes sense ... any comments about these ideas?

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