SMD DD1 not registering head unit distortion

[JohnPD]

I've tried it both ways as per the manual, and no matter what it won't register distortion even with the head unit volume all the way up. It does however register distortion of the amp no matter the head unit volume level. Any ideas?

[audiofanaticz]

Some but not all headunits will not distort at max volume when only using rca preouts.
Now if you're using the internal amp of the headunit that will usually distort long before the rca preouts will so you will want to use that as your max volume setting.

[nauc]

i have a Alpine 9887 and a scope, the RCA outs dont clip at full volume.  the internal amp clips at volume 21 out of 35 

[x90e]

I dont suppose anyone knows off hand what volume level the pioneer dmh-160bt or the kenwood kdc-x998 clip at?

 

[JohnPD]

On 7/14/2023 at 4:53 AM, audiofanaticz said:

Some but not all headunits will not distort at max volume when only using rca preouts.
Now if you're using the internal amp of the headunit that will usually distort long before the rca preouts will so you will want to use that as your max volume setting.

Yes, I'm using the rca preouts to a 4 channel amp, and my preout voltage is 5volts, so it will produce less noise to begin with. I'm guessing that I just set the head unit volume to the loudest I want, then use the dd1 to set the gains on the amp

[audiofanaticz]

On 7/16/2023 at 9:53 PM, x90e said:

I dont suppose anyone knows off hand what volume level the pioneer dmh-160bt or the kenwood kdc-x998 clip at?

 

There is a thread, though it maybe buried now that has a bunch of radios that people tested with the dd-1 for max undistorted volume. you will probably have to search for it though.

21 hours ago, JohnPD said:

Yes, I'm using the rca preouts to a 4 channel amp, and my preout voltage is 5volts, so it will produce less noise to begin with. I'm guessing that I just set the head unit volume to the loudest I want, then use the dd1 to set the gains on the amp

If the radio is not showing distortion direct through the rca's or while attached to an amp with the gain at 0 when you use a 0db tone for 40hz and 1000hz then it is safe to say the radio is distortion free at max volume through the rca preouts. In that case then set your amp(s) using your desired overlap -5, -10, etc db level at the maximum headunit volume.
You could use a lower volume if you really wanted but it won't change much except the fact that the radios preout voltages (5 volts as you said in your case) typically wont be achieved unless the volume is all the way up. So if your volume goes to 40 and its clean at 40 you will get 5 volts preout voltage, but say if it goes to 40 but you set it to 20 to tune your amps then your rca preout voltage will only be 2.5volts or there abouts which will require you to increase the gain on the amp to compensate for that lower signal due to having lesser preout voltage. So you should just use the max cleanest volume.

[JohnPD]

Ok, I started from scratch. with a fresh battery in the DD1. My head unit's volume goes to 40. I tested at the amp, and playing the 40hz tone, the head unit distorts at 28, so I wrote down 27, then playing the 1000hz tone I can go all the way to 40. I averaged the two and used 33 as my volume to set my amp gains. The system sounds good, but I'm wondering why I get head unit distortion at 40hz and not at 1000hz? Is this something to be concerned about?