question on pre eq patch on nashville 400
Moderator: Shoshanah Marohn
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Byron Burton
- Posts: 18
- Joined: 6 Oct 2009 3:15 pm
- Location: Louisiana, USA
question on pre eq patch on nashville 400
i was wondering if the eq patch in/out was just an effects loop. my set up is mullen d10 to matchbox/goodrich L120 vp/ dd3/to input 1 on the amp. if the patch in/out is an effect loop, should i run the dd3 through it? i think it sounds good the way it is but just looking for other options.
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Byron Burton
- Posts: 18
- Joined: 6 Oct 2009 3:15 pm
- Location: Louisiana, USA
I posted this a while back about the loops on the N112 amp and overlap they cause (N400 is similar):
As you can see both the effect loops on the N112 provide too much signal for optimum headroom and signal to noise ratio. The best choice would be the Pre EQ for the least amount of gain overlap (40 mv of overlap). This mean you cannot drive the amp to full power without clipping the reverb unit first!!
The post EQ is worse with 121mv of gain overlap.
RV-5
Nominal Input Level
-20 dBu 77mv
Input Impedance
1 M ohms
Nominal Output Level
-20 dBu 77mv
Output Impedance
1 k ohms
Recommended Load Impedance
10 k ohms or greater
N=112
Pre EQ patch send:
Load impedance: 10k Ohms or greater
Nominal output level: -18.6 dBV, 117 mV RMS
Pre EQ patch return:
Impedance: High Z, 220 k Ohms
Designed Input Level: -18.6 dBV, 117 mV RMS
Post EQ patch send:
Load impedance: 10 k Ohms or greater
Nominal output level: -14.1 dBV, 198 mV RMS
Post EQ patch return:
Impedance: High Z, 1 m Ohms
Designed Input Level: -14.1 dBV, 198 mV RMS
_________________
As you can see both the effect loops on the N112 provide too much signal for optimum headroom and signal to noise ratio. The best choice would be the Pre EQ for the least amount of gain overlap (40 mv of overlap). This mean you cannot drive the amp to full power without clipping the reverb unit first!!
The post EQ is worse with 121mv of gain overlap.
RV-5
Nominal Input Level
-20 dBu 77mv
Input Impedance
1 M ohms
Nominal Output Level
-20 dBu 77mv
Output Impedance
1 k ohms
Recommended Load Impedance
10 k ohms or greater
N=112
Pre EQ patch send:
Load impedance: 10k Ohms or greater
Nominal output level: -18.6 dBV, 117 mV RMS
Pre EQ patch return:
Impedance: High Z, 220 k Ohms
Designed Input Level: -18.6 dBV, 117 mV RMS
Post EQ patch send:
Load impedance: 10 k Ohms or greater
Nominal output level: -14.1 dBV, 198 mV RMS
Post EQ patch return:
Impedance: High Z, 1 m Ohms
Designed Input Level: -14.1 dBV, 198 mV RMS
_________________
This was an earlier reply on the N-400 amp itself:
After 30 years of experience and training with the design of audio systems I know a bit about overloading devices.
Let's take a Boss RV-5 pedal for example:
nominal input level rated for -20dbu (0.21 volts)
Nominal level is the normal operating signal that allows 10db of headroom in live music or 20db of headroom in recording application to allow for volume dynamics associated with playing or recording music. That from my old Yamaha manuals of years ago!!!
The preamp output of the N-400 is 1 volt nominal and can go as high as 8 volts! That is 5 times the nominal voltage the Boss RV-5 want to see for it normal operating range and best signal to noise ratio.
The RV-5's nominal output is also -20dbu, 5 times to weak to properly drive the power amp of the N-400 amp.
The patch output of the N-400 is amazingly a nominal of 0.2 volts, same as the effects pedal requires!
The patch input of the Nashville 400 is 0.2 volts, the same as the nominal output of the effects pedal.
There is no supporting argument for using the preamp to drive a common effects pedal. Those pedal are designed for unity gain and a guitar level signal at their input.
So in layman's terms. using the pre-amp out to feed a common effect pedal is like trying to shove 5 lbs of stuff in a 1 lbs bag.
Your choice, do it either way. I just believe in the things I learned while I studied and trained in the Pro Audio field to preserve proper signal to noise ration and prevent gain overlap (that leads to distortion)
I could go on further into gain overlap, impedance matching and a ream of other subject matter but I do not think it necessary for this application!!
A bit more from the net about operating levels:
Nominal level is the operating level at which an electronic signal processing device is designed to operate. The electronic circuits that make up such equipment are limited in the maximum signal they can output and the low-level internally-generated electronic noise they add to the signal. The difference between the internal noise and the maximum output level is the device's dynamic range. When a signal is chained improperly through many devices, the dynamic range of the signal is reduced. The nominal level is the level that these devices were designed to operate at, for best dynamic range.
In audio, a related measurement, signal-to-noise ratio, is usually defined as the difference between the nominal level and the noise floor, leaving the headroom as the difference between nominal and maximum output.[1][2] It is important to realize that the measured level is a time average, meaning that the peaks of audio signals regularly exceed the measured average level. The headroom measurement defines how far the peak levels can stray from the nominal measured level before clipping. The difference between the peaks and the average for a given signal is the crest factor.
There is some confusion over the use of the term "nominal", which is often used incorrectly to mean "average or typical". The relevant definition in this case is "as per design"; gain is applied to make the average signal level correspond to the designed, or nominal, level.
After 30 years of experience and training with the design of audio systems I know a bit about overloading devices.
Let's take a Boss RV-5 pedal for example:
nominal input level rated for -20dbu (0.21 volts)
Nominal level is the normal operating signal that allows 10db of headroom in live music or 20db of headroom in recording application to allow for volume dynamics associated with playing or recording music. That from my old Yamaha manuals of years ago!!!
The preamp output of the N-400 is 1 volt nominal and can go as high as 8 volts! That is 5 times the nominal voltage the Boss RV-5 want to see for it normal operating range and best signal to noise ratio.
The RV-5's nominal output is also -20dbu, 5 times to weak to properly drive the power amp of the N-400 amp.
The patch output of the N-400 is amazingly a nominal of 0.2 volts, same as the effects pedal requires!
The patch input of the Nashville 400 is 0.2 volts, the same as the nominal output of the effects pedal.
There is no supporting argument for using the preamp to drive a common effects pedal. Those pedal are designed for unity gain and a guitar level signal at their input.
So in layman's terms. using the pre-amp out to feed a common effect pedal is like trying to shove 5 lbs of stuff in a 1 lbs bag.
Your choice, do it either way. I just believe in the things I learned while I studied and trained in the Pro Audio field to preserve proper signal to noise ration and prevent gain overlap (that leads to distortion)
I could go on further into gain overlap, impedance matching and a ream of other subject matter but I do not think it necessary for this application!!
A bit more from the net about operating levels:
Nominal level is the operating level at which an electronic signal processing device is designed to operate. The electronic circuits that make up such equipment are limited in the maximum signal they can output and the low-level internally-generated electronic noise they add to the signal. The difference between the internal noise and the maximum output level is the device's dynamic range. When a signal is chained improperly through many devices, the dynamic range of the signal is reduced. The nominal level is the level that these devices were designed to operate at, for best dynamic range.
In audio, a related measurement, signal-to-noise ratio, is usually defined as the difference between the nominal level and the noise floor, leaving the headroom as the difference between nominal and maximum output.[1][2] It is important to realize that the measured level is a time average, meaning that the peaks of audio signals regularly exceed the measured average level. The headroom measurement defines how far the peak levels can stray from the nominal measured level before clipping. The difference between the peaks and the average for a given signal is the crest factor.
There is some confusion over the use of the term "nominal", which is often used incorrectly to mean "average or typical". The relevant definition in this case is "as per design"; gain is applied to make the average signal level correspond to the designed, or nominal, level.