Correct
When I had check a few different stock head units of the pre Rushmore bikes that I had done installs on they were showing a distorted signal out at 1/2 volume with a 1k and 40hz test tone using a DD-1

 

yeah but what does that really mean? that you can't raise the volume passed 1/2.....then why not set the gains there. Was the distortion level the same for high level and low level inputs, what about -5db or -10db test tones. I agree the stock HU is pretty crappy but if that's all a guy has to work with then we should find work arounds or solutions when "just buy another headunit" is not possible.

 

I was able to tame the distortion by lowering the input signal to the amp by means of a pac sni-35 line converter.

I know most people don't have access to a distortion detector or a scope. Most either use a DMM or caveman method of setting by ear.

Normally after each step on a install after finding the sweet spot I will take down voltage readings for a reference and for some reason I did not do that on the last stock head unit I used on an upgrade.
If I had the numbers I would gladly pass them on.
I do remember the the gains on the sni35 were around the 9:30 to 10 o'clock position with the volume at 3/4.

 

^ that's making the most of it, for sure!!!

 

I just lined up an install for this evening using a pre Rushmore HK head unit so I will have some solid number to go off of for other to use for a reference when using a line out converter

 

sounds good. list of all components too?

 

http://www.wccaraudio.com/smd-distor...ctor-dd-1.html

video here but disregard the second device.
Nice cheap option

 

Install is complete
Bike was an 01 street glide with stock Radio Sounds HU.
PAC SNI 35 line converter
Arc is 125.2 bx amp
Rockford fosgate 6.5 speakers

TESTING EQUIPMENT USED
SMD DD1
BLUE POINT 586 DMM


Using a 1k -10db at 3/4 volume was the happy spot on the head unit (not showing any distortion)
The line out converter was set with same test tone with 1.01 volts (11oclockish) before showing any distortion.
Amp was showing distortion at 20 volts with a clean input signal. I wound up setting the amp at 17.3 vac which was 75 watts rms per the manufacturer.

Note :When Using a stock Radio Sounds HU the Arc 125.2 amp is just about the biggest amp you will be able to fit on top of the HU without any modifications

 

So how does it sound?

 

The system sounded warm with good punchy bass with a good balance of highs that were not shrill sounding.