trouble using DD-1

[Todd Geisler]

Redoing the stereo in my new car trailer, upgrading components. I purchased the DD-1 to be able to accurately set the amplifier gain.

The head unit is a Kenwood KDC-BT572U, one of the only components I didn't upgrade (yet). This head unit is rated at 2.5 volts on the pre-outs. I measured, cant find my notes but I believe it was around 2.3 volts actual measured. The volume goes to 35 total, found the preouts didn't show distortion on the DD-1 till 33 on the volume. One odd thing is the DD-1 didn't see the 1khz signal till the head unit was at 32 on the volume. I see in the instructions the DD-1 needs to see 1.2 volts to recognize the signal. With this head unit, that puts it at very high volume. The voltage to volume setting isn't very linear. The voltage stays below 1 volts for quite a long time, then ramps up the last 1/4 of the volume it seems.

I verified three sources for distortion, CD, Bluetooth and USB, all three showed the same volume level vs distortion within one volume number.

I then connected the head unit to the new JL Audio XD400/4v2 amplifier with the speaker outputs unhooked. Gains set all the way down, DD-1 leads hooked to the front speaker output on the amp. The DD-1 showed distortion with very low volume on the head unit. Per the instructions said to try -5db which showed distortion at mid volume and zero gain. Wound up having to use the -10db to set the gain and not have distortion show up.

I'm confused why the DD-1 shows distortion through the amp when the head unit output was clean?

I have everything adjusted with the -10db, sounds good, had to turn down the front channels to match the rear channels with how the amp is wired, but either way the sound is clean, so no real concerns over the distortion.

Starting to think part of the problem is the average out put of the preouts being only 2.5 volts. I've considered replacing the head unit with the Pioneer DEH-80PRS which has 5 volts outout.

I hope this babbling makes some sense.

thanks

Todd

[Joshdashef]

When you found the clipping point of your radio with the RCAs hooked into the amp but the speaker wires unplugged, were all your filters set off or crossovers set so they don't interfere? 

Check any eq setting on your radio, turn them off, see if that makes a difference. 

It is possible the radio is the route of all the trouble or it could be an RCA dud. Pull all your RCAs out and check the connections to make sure they are tight and not loose just in case. 

Try changing the battery in the DD-1 for a fresh one. 

Try the 40hz - 0db track, and see if it gives you any different results. 

It is possible that you are seeing expected distortion at 1/2 to 3/4 volume and that is just normal for the radio, not many aftermarket radios can go all the way up without distortion. 

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You mentioned you were looking at the DEH 80 PRS, this is the current radio I am using and although I haven't measured the voltage of my RCAs, the radios limit is 62 but with volume source input +1 (bluetooth Iphone) I don't clip until 62, so I tuned at 61. 

Only issues I have with this radio is the screen is not very bright during the day, at night it is no problem. Also it has two modes network and standard - I have only used network mode since I am using an active setup so all my crossovers are within the radio instead of on my amps. 

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Btw nice wire job, looks clean as hell man!

[CstrokerV]

the Amp produces distortion also that’s why you have to dd1 every item in the line when you  use it... the dd1 is used to match the voltage from the deck so if it hits 2 volts and it produces the 1% distortion the light comes on..  and not seeing the 1k as long as it sees it before the distortion light comes on then it should be ok. I’m assuming.....  my deck had 0 distortion with volume all the way up and with the sub out all the way up... but it’s also a 4 volt output