I'm about to hook my new HTP-1 up to my system tomorrow. I'm a bit new when it comes to all this talk of maximizing the dynamic range and SINAD of the HTP-1 and using the gain sensitivity setting to help.
My trouble is that I have a mix of amps right now, and so I am a bit flummoxed as to how I should set the HTP-1 (and also gain level match as best I can given the disparate input voltages).
The 4 ohm rated LCR speaker amp is a Purifi 3-channel unit with three 4 ohm gain choices of: 25.5dB/2.17Vrms (High), 20.5dB/3.89Vrms (Medium), 15.5dB/6.93Vrms (Low)
The outlaw has a gain of 29 dB, so the Purifi at 25.5 dB will be decently close since it'll see twice the voltage. You don't have to stress about matching the gain levels since you won't be using identical speakers at identical distances, so the processor will correct the levels appropriately.
The key is what you're listening to and how loud you want to be. You can use the SPL calculator here:
http://www.hometheaterengineering.com/splcalculator.html
In the high gain mode, when the HTP-1 is outputting 2.1V, it will end up at 40V (40*40/4 = 400 watts).
To hit 6 watts, which is probably loud, the HTP-1 is outputting 0.27V at the pre-amp stage. ~93 dB SINAD
In the medium gain mode, when the HTP-1 is outputting 3.8V, it will end up at 40V (40*40/4 = 400 watts).
To hit 6 watts, which is probably loud, the HTP-1 is outputting 0.47V at the pre-amp stage. ~96 dB SINAD
In the low gain mode, when the HTP-1 runs out of steam at 4.1V, it will end up at 24.4V. Your Purifi will never be asked to put out more than 150 watts.
To hit 6 watts, which is probably loud, the HTP-1 is outputting 0.84V at the pre-amp stage. >100 dB SINAD
For your 29 dB Outlaw, it needs 0.17V to hit 6 watts. ~89 dB SINAD if you had configured your HTP-1 to limit itself to 2.2V. ~85 dB guesstimate if you set it up for 4.1V max.
So, long story short,
1) If 150W of clean power is loud enough for your front channels, I'd set your HTP-1 for "7V" maximum and your Purifi at the lowest gain, so that it outputs a high voltage to your LCR speakers which is the most important. At 95 dB SINAD at 0.56V, that's great. The super-expensive Trinnov only hits 92 dB SINAD at that lower level.
2) If 6 watts of power gives you 90 dB of SPL with your speakers/distances, then all of this is academic since everything breaks the 90 dB SINAD threshold. You can imagine that if 6 watts of power gets you to 85 dB of volume and your noise and distortion is at -93 dB, then it's purely academic since the noise/distortion should be negative dB (below 0).
You basically have to make a table to figure out what gives you your best SINAD are your target listening volume while still giving you enough headroom for 20 dB of swing.
Gain and loss - damping and amplification in dB voltage conversioncalculation amplification amplifier electronics - field parameter - Eberhard Sengpiel sengpielaudio
www.sengpielaudio.com
Lets you input your pre-amp output voltage, use the gain reported by the amplifiers to get the voltage at the speaker stage, and then you can do voltage squared divided by resistance = watts
The 7140 manual said to use shorting pins on Pins 1 and 3 of the XLR inputs if using the RCA connections. Is that necessary if the XLR to RCA cables are wired correctly or are the pins a safety precaution?
Yes, you need to do this.*
The manual says so. But this is important if your Outlaw is a true balanced amp. If it's a true balanced amp (and not just a balanced amp that converts to single ended), when you don't have the jumper, the negative input of the amp is floating which could drop your gain.
But you have an HTP-1 with XLR outputs. "Cables" don't matter in the sense of fancy materials, but XLR has benefits. You should very much spend the money to use XLR cables to the Outlaw amplifier.
