I just purchased a 4ch Crunch DSVU line driver/preamp. So the rca's
from my pioneer deh-p7400mp run into the line driver then into my 2
amps. The amps are lanzar rack series. One is a 900.2 powering two
12" subs and the other is a 250.4 driving six other drivers in the
front soundstage. My reason for purchasing the line driver was for
the 2 built in analog VU meters. But now I'm having to contend with
this issue:

OK soooo

What's the proper way to use a line driver. There are adjustments on
it that allow me to increase the volts for both the 1/2 channel and
the 3/4 channel. It appears that I can +/- the volts from 0 up to 12
volts. I do split the front output rca into 2 which I then plug into
my 4 channel amplifier. So I understand I'm halving the signal volts
that my headunit allots for those channels. My question is: What
should I be cautious of here? Is there a specific volt level I should
set. How high should I increase it? Can I damage my amplifiers by
sending to high of signal volts into it's inputs?

This is an expensive game we're all messed up in here isn't it. Just
want to take care of my gear.

Thanks

eidsvikDM wrote
What's the proper way to use a line driver. There are adjustments on it
that allow me to increase the volts for both the 1/2 channel and the 3/4
channel.
It appears that I can +/- the volts from 0 up to 12 volts. I do split the
front output rca into 2 which I then plug into my 4 channel amplifier.

Why are you using a splitter on the RCAs?

So I understand I'm halving the signal volts that my headunit allots for
those channels.

That is not true. Splitting the outputs is running them in parallel, which
means the voltage remains constant. You have halved the impedance.

My question is: What should I be cautious of here?

If you set gains on the line driver too high, you could overdrive the inputs
of the amp. Basically, if the amp inputs are rated to handle =4V and you
run 6V into the amp, it will clip.

Is there a specific volt level I should set.

What is the output voltage of your head unit? What is the input voltage
range of your amp?

How high should I increase it?

Ideally, if you set the line driver up properly, you can leave the gains on
the amp at their minimal levels.

Can I damage my amplifiers by sending to high of signal volts into it's
inputs?

Yes.

--
Regards,
Dan Snooks

Hey really appreciate your input....to answer a few questions....

Why are you using a splitter on the RCAs?
My HU has only 2 rca outs at the rear. One labeled front and one
labeled rear. I've selected the rear rca (within the HU on screen
settings) as a subwoofer. I run that signal to the line driver then
onto the 900.2 amp that runs my subs. The front rca output goes to
the line driver then onto the four channel amp that runs 2 pairs of
drivers in the front and 1 pair of drivers on the rear deck. I use a
Y splitter on this single cord and then plug it in to the four channel
amp. This was the area where I was concerned about halfing the signal
strength.

That is not true. Splitting the outputs is running them in parallel, which
means the voltage remains constant. You have halved the impedance.

This I didn't know. I'm getting pretty serious about the DIY thing
and thought that impedance was only manipulated by changing the wiring
configuration to the drivers from the amplifier. Didn't know that HU
output signal had that affect.

If you set gains on the line driver too high, you could overdrive the inputs
of the amp. Basically, if the amp inputs are rated to handle =4V and you
run 6V into the amp, it will clip.

Ok this may make sense. I'm gonna check my line driver and see what I
have it set to. I'm not sure what clipping is our sounds like but I
think I may be experiencing that.

What is the output voltage of your head unit? What is the input voltage
range of your amp?

Output voltage is 4v for the HU and a range is given for my amp 100mv
~ 4v

Ideally, if you set the line driver up properly, you can leave the gains on
the amp at their minimal levels.

I understand that the gains on an amp aren't volume controls. Are you
stating I should match the gains with the signal level? Keep them as
low as possible?
They are aet at about 35% now for the 4ch and about 50% for the subs?

Hey you are giving me a real hand here. I appreciate it.

Off to do some tuning

-Jason

Hey Jason... how do you like those lanzar rack amps?
Have you had any problems with them? Can they handle a 2 ohm load? Are
they pretty reliable?

Thanks!!
Garrett

eidsvikDM wrote:

Hey really appreciate your input....to answer a few questions....

Why are you using a splitter on the RCAs?
My HU has only 2 rca outs at the rear. One labeled front and one
labeled rear. I've selected the rear rca (within the HU on screen
settings) as a subwoofer. I run that signal to the line driver then
onto the 900.2 amp that runs my subs. The front rca output goes to
the line driver then onto the four channel amp that runs 2 pairs of
drivers in the front and 1 pair of drivers on the rear deck. I use a
Y splitter on this single cord and then plug it in to the four channel
amp. This was the area where I was concerned about halfing the signal
strength.

That is not true. Splitting the outputs is running them in parallel, which
means the voltage remains constant. You have halved the impedance.

This I didn't know. I'm getting pretty serious about the DIY thing
and thought that impedance was only manipulated by changing the wiring
configuration to the drivers from the amplifier. Didn't know that HU
output signal had that affect.

If you set gains on the line driver too high, you could overdrive the inputs
of the amp. Basically, if the amp inputs are rated to handle =4V and you
run 6V into the amp, it will clip.

Ok this may make sense. I'm gonna check my line driver and see what I
have it set to. I'm not sure what clipping is our sounds like but I
think I may be experiencing that.

What is the output voltage of your head unit? What is the input voltage
range of your amp?

Output voltage is 4v for the HU and a range is given for my amp 100mv
~ 4v

Ideally, if you set the line driver up properly, you can leave the gains on
the amp at their minimal levels.

I understand that the gains on an amp aren't volume controls. Are you
stating I should match the gains with the signal level? Keep them as
low as possible?
They are aet at about 35% now for the 4ch and about 50% for the subs?

Hey you are giving me a real hand here. I appreciate it.

Off to do some tuning

-Jason

Just red your other post... thanks!!
Garrett


Sanitarium wrote:

Hey Jason... how do you like those lanzar rack amps?
Have you had any problems with them? Can they handle a 2 ohm load? Are
they pretty reliable?

Thanks!!
Garrett

eidsvikDM wrote:

Hey really appreciate your input....to answer a few questions....

Why are you using a splitter on the RCAs?
My HU has only 2 rca outs at the rear. One labeled front and one
labeled rear. I've selected the rear rca (within the HU on screen
settings) as a subwoofer. I run that signal to the line driver then
onto the 900.2 amp that runs my subs. The front rca output goes to
the line driver then onto the four channel amp that runs 2 pairs of
drivers in the front and 1 pair of drivers on the rear deck. I use a
Y splitter on this single cord and then plug it in to the four channel
amp. This was the area where I was concerned about halfing the signal
strength.

That is not true. Splitting the outputs is running them in parallel, which
means the voltage remains constant. You have halved the impedance.

This I didn't know. I'm getting pretty serious about the DIY thing
and thought that impedance was only manipulated by changing the wiring
configuration to the drivers from the amplifier. Didn't know that HU
output signal had that affect.

If you set gains on the line driver too high, you could overdrive the inputs
of the amp. Basically, if the amp inputs are rated to handle =4V and you
run 6V into the amp, it will clip.

Ok this may make sense. I'm gonna check my line driver and see what I
have it set to. I'm not sure what clipping is our sounds like but I
think I may be experiencing that.

What is the output voltage of your head unit? What is the input voltage
range of your amp?

Output voltage is 4v for the HU and a range is given for my amp 100mv
~ 4v

Ideally, if you set the line driver up properly, you can leave the gains on
the amp at their minimal levels.

I understand that the gains on an amp aren't volume controls. Are you
stating I should match the gains with the signal level? Keep them as
low as possible?
They are aet at about 35% now for the 4ch and about 50% for the subs?

Hey you are giving me a real hand here. I appreciate it.

Off to do some tuning

-Jason

eidsvikDM wrote
Hey really appreciate your input....to answer a few questions....

My HU has only 2 rca outs at the rear. One labeled front and one
labeled rear. I've selected the rear rca (within the HU on screen
settings) as a subwoofer. I run that signal to the line driver then
onto the 900.2 amp that runs my subs. The front rca output goes to
the line driver then onto the four channel amp that runs 2 pairs of
drivers in the front and 1 pair of drivers on the rear deck. I use a
Y splitter on this single cord and then plug it in to the four channel
amp. This was the area where I was concerned about halfing the signal
strength.

Many 4 channel amps have an option to share a single pair of input. In other
words, you plug a pair of RCAs into channels 1 & 2, then set the amp to use
the same signal for channels 3 & 4. Check and see if your amp has this
feature, it is far superior to using a Y.

Output voltage is 4v for the HU and a range is given for my amp 100mv
~ 4v

So, basically what this means is that you don't need a line driver :-)
Heh, anyway, you like the nifty display, set the line driver to output 4V.

I understand that the gains on an amp aren't volume controls. Are you
stating I should match the gains with the signal level?

Yes. Read on.

Keep them as low as possible?

Absolutely. Here is a scenario. You are using a 4V output head unit and the
amp can handle 100mV ~ 4V input (sound familiar?). You set the gains on the
amp to minimum (turned fully counter-clockwise). When you play music, as you
increase the volume on the head unit, the voltage output of the head unit
increases (for example ... 25% volume = 0.8V, 55% volume =1.8V, 80% volume =
3.7V). Notice that the output voltage doesn't really match the rated output
levels like it should ... this is typical.

The idea of leaving the gains at the minimum setting on the amp is that it
will take a 4V input to get full power output from the amp. Hence, when you
turn the gains UP on the amp (clockwise) you increase the sensitivity of the
input. At maximum gain, the amp will only need an input voltage of ~100mV to
get full output.

They are set at about 35% now for the 4ch and about 50% for the subs?

So, in your case the 4 channel amp will produce full power when the input
level reaches about 2.7V and the sub amp will reach full power when the
input level reaches 2V.

Are you able to turn the head unit volume up past 75% without the music
being distorted? What volume setting on the head unit do you normally listen
at?

Hey you are giving me a real hand here. I appreciate it.

My pleasure, hope any of this helps.

--
Regards,
Dan Snooks