Experience setting gains with SMD DD-1 with JBL HU and Kappa 5 amp

System is a JBL HU--->DSR1--->Infinity Kappa 5-channel Amp. I was able to get ahold of a SMD DD-1 distortion meter. Everything was measured at the amp channel outputs after disconnecting all speaker wires.

1. JBL Head Unit - Followed instructions in manual and believe it or not no distortion until a volume of 59. Back it down to 58 and no distortion. Put it up one to 59 and there's distortion. Repeated this process several times.

2. I set the gains on the front/rear channels first following the instruction manual. These ended up pretty close to where I had arbitrarily set them. They end up being a hair above 9 O'clock.

3. Set the bass channels following the instruction manual and this was lower than where I thought I'd be. This ended up being at about 10:30.

I also turned my amp 180 degrees so the adjustments were towards the door for easier adjustment. Just as I was finishing up the amp went into protection mode - solid red light with no blinking. I thought crap what did I do? I checked all my connections and the manual and this can be triggered if there's an insufficient voltage. Sure enough, I went to start the truck and the battery was almost dead. Jumped it and drove it and everything is working perfectly. The gains are set and I won't be touching those again. Hoping this may help some with the JBL HU and either the Kappa 5 or JBL Stadium 5 amps (same amps).

 

Oh yeah...I ripped the CD provided with the DD-1 and it automatically uploaded to Apple Music so I could play the appropriate track through my phone.

 

I have a question:

When I tested for distortion I was able to put the stock JBL HU volume all the way up to 58 before there was distortion detected (with 60 being the maximum for the HU). I then proceeded to set the gains for the sub and K170's at a HU volume of 58. I have never listened to music even at a volume of 50 and my maximum tends to be 45-47. Does it make more sense to repeat the process of setting the gains for the K170's and sub using a lower HU volume that is closer to the volume I actually listen to? System is crystal clear up to 50 it just gets so loud it's no longer enjoyable.

In other words, are my gains actually set lower than they could be before producing distortion because I had the HU turned up so high?

I have very little idea what I'm actually doing but I'm learning and as always help always appreciated.

 

@PWMDMD right there with you. Trying to figure out how to do all the gains correctly. Just finished my install yesterday and trying to get the tuning correct. I purchased a sine wave reader/cheap oscilloscope off that I’ll be using to set my gains. What I’m trying to figure out is how the settings in the DSR1 affect the distortion point. I would think the gain level in the DSR1 affects the setting on the amp, so I guess flatten everything on the HU and DSR1 and go from there? Hopefully someone can provide some insight

 

You can set them with a volt meter. For woofers/doors its typical to us a 1kHz signal with 0db boost. Use a voltage/amp/watt/resistance calculator to find the values you need.

For example, in your typical 4ohm speaker, with a 100W amp channel, you would adjust the volume to typically to 75% max and increase gain until it hits 20v. 20v target is found by either using the calculator or knowing the ohms law algorithms. In this case Voltage=Current/resistance.

Theres a lot more to it than that, but this method works well enough to keep your speakers safe. You could also adjust it based off the volume being set to 100% of the head unit, but you'll find yourself turning it up more, of course.

 

The DSR1 does an excellent job of flattening everything out. I've used an iOS app to play pink noise through the system and it was really very flat up to the x-over frequency of the sub and I just wasn't close enough to measure that at the sub. My advice is to leave the DSR1 as is and make all adjustments at the amp. I'm not sure when you pull the negative terminal of the battery if all the settings in the DSR1 would be lost but at the amp you know they are set until you adjust them.

 

Yes, just be aware that if you go above those settings clipping can occur. For me I prefer to tune that way, so that peak volume is achieved sooner, I find little use for the low volume settings when tuned with the volume maxed. Also the stock HU cuts/attenuates power to certain frequencies as it gets louder, so it can be better to tune it to peak at lower volumes.

 

Any pre amp input can boost certain frequencies. So you have to be mindful of that boost, if you tune the power with a 1khz signal and the boost for that frequency is +0db but you have 800hz or 600hz at +3 or +6db and your speakers are not crossed over there (they shouldnt be), you may have clipping that you're unaware of.

 

I really like the DD-1 because you first set the HU volume and then the gains. Turns out the JBL HU doesn't clip until a volume of 59. If you just arbitrarily set the HU volume at 75% of the max of 60 you'd get a volume of 45. If you set the gains at a volume of 45 instead of 58 aren't you leaving a lot on the table?

Edit: Just read your response above - so yes you are leaving some volume on the table BUT for me it unusable anyway since it's already too loud above 50.

 

So it's best to allow the DSR1 to flatten everything out and adjust at the amp?

 

The opposite. You tune the max amp power (gain) to that volume. The amp will slope power to max at that volume. Its arbitrary to the power max, if you tune it to 20, 40, or 60. Gain is the slope increase of power, if you tune it to 20 it will reach max power with little input. You can leave power on the table by under or conservatively driving the gain.

 

Its best to use the DSR1 to tune the sound quality first, then tune your gain accordingly. If thats not the order you did it in, I would recommend tuning the DSR1 to your preference, and then recheck the gain/clipping. If you boosted some of the lower frequencies make sure to check clipping at those signals if you can.

 

First, I just want to say thank you for your help and patience!

1. When I played pink noise all the frequencies were flat. This is not a bad starting point correct? I have little desire to adjust the 33 bands and Q-values in the DSR1.

2. So, right now my amp gains were set at a HU volume of 58 but I find a volume over 50 to be intolerable. If I set the HU volume at say 52 and set the gains on the amp and promise to never go above a volume of 50, I should be able to set the amp gains a little higher than they're currently set and use a little more of the amp at a volumes of 50 and below?

Really do appreciate the help!