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Quiet amp for active K-402


Ivaols

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Is the hiss there if you turn your preamp off?  (if mentioned above, I missed it)

 

What I did was worked backwards....  whole system off.  Went to power amps & turned only those on.  Dialed gains (which I don't know if yours has) up until I heard some hiss...backed them down till it was dead quiet.

 

Went to active, turned it on...

 

Went to preamp, turned it on and with the gains all the way DOWN, turned the volume control to 100%.  Last, I started moving the gains on the preamp up until I had it as loud as I might want to "normally" listen to.  Actually, I took it a bit higher to let me jam every now & then....but otherwise, left it at that level.

 

Now, I have to turn the preamp up higher to get my signal and it not only sounded better but, I had no hiss.

 

My opinion, variable gains/attenuators are your friend.

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What's the input sensitivity of that amp?  I looked it up and didn't see it (in an obvious location) on their website.

 

I used to have a dbx BX-1 that as i recall, had an input sensitivity of 1v and it was a real bugger trying to keep it quiet.

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34 minutes ago, Chris A said:

I'll send you an updated .xdat file that greatly increases the input channel gains.  It appears to be a gain staging issue.  I would bet it's your preamp (which you haven't identified here) not driving the signal chain with enough output.  The Xilicas have all been dead quiet quiescently in the setups that I've used them in.

 

Chris

 

Thank you. The preamp is a receiver, Marantz SR6012.

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20 minutes ago, Ivaols said:

There is still one input without connection, and two outputs without connection.

OK we're talking about the Xilica, right? That should be ok as long as the unused input is not assigned to any of the used outputs. So the inputs of the Xilica come from a reciever over balanced or un balanced lines?

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2 minutes ago, babadono said:

OK we're talking about the Xilica, right? That should be ok as long as the unused input is not assigned to any of the used outputs. So the inputs of the Xilica come from a reciever over balanced or un balanced lines?

Yes, we're talking about the Xilica. 

The unused input is not assigned to anything. 

Signal from receiver is unbalanced. 

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1 hour ago, Coytee said:

What's the input sensitivity of that amp?  I looked it up and didn't see it (in an obvious location) on their website.

 

I used to have a dbx BX-1 that as i recall, had an input sensitivity of 1v and it was a real bugger trying to keep it quiet.

Input sensitivity for full rated power is 1.8v.

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Here is what I tested:

With only the amp on there is hardly any hiss.

With the amp on and the Xilica turned on the hiss appears.

With the amp on and the Xilica on it is no difference between pre on or off, the hiss is there all the time with same intensity.

Reducing the input gain from the pre to the Xilica has no effect, the hiss is the same.

 

Confused...

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The Xilica mutes when it's not being driven.  Something is wrong on the input side of the Xilica if it isn't automatically muting.

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See page 23 of manual for settings of the ISO (internal system optimizer). I think muting can be turned off. This is the Xilica I'm talking about. I can't seem to copy the manual and paste it here. ?????      I r n idiot with computer stuff sometimes.:sad:

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In fact, I'd recommend raising the threshold of muting above the level "102" to see if that controls the quiescent hiss.

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Does this muting involve the actual relays and buttons on the front of the unit? Or is it a software muting of the DSP? I need to go home and mess with mine. Is this setting, the threshold of the mute, available in the XConsole App.?

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I accessed the function from the front panel-turning it to "bypass".  I heard no increased hiss levels after doing this--there was no audible hiss.  So I believe that, in my setup, there is no need for the Internal System Optimizer (ISO) muting function. 

 

However, in Ivan's case--there may be a need.

 

Chris

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In Ivan's case, if he's already got audible hiss then either the muting function is not set high enough or there is significant EMI on the XLR output cables to his amplifier.  The Xilica is dead quiet in all the setups that I've used (XP-4080s for others , XP-8080 in my setup). 

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I re read the manual about the ISO and it is a "noise gate" and I'm sure its done in the DSP. So Ivan should be able to adjust it until he can definitely hear it cutting in and out if it is like any kind of noise gate I've ever used. Now I definitely want to see where mine is set and experiment with it.:)

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9 hours ago, Ivaols said:

As of now I have to lower the gain by minus 9.5db in the Xilica for the K-402 output. If I can open it up to 0 dB and lower the gain on the amp side it will provide better s/n ratio. 

 

5 hours ago, Ivaols said:

With only the amp on there is hardly any hiss.

 

Are you lowering the gain by -9.5 so that you can drive the Xilica’s Input at a good level as read on the Xilica’s Input Meters..?

 

If the above is the case then even if you can adjust the Mute level of the Xilica it sure looks to me like you would benefit from attenuators on the amplifiers inputs due to the input sensitivity and gain of the amplifier.

 

miketn

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