SMD DD-1 compared to JBL GTO EZ-501 Amp (internal gain setting technology)

[30Hz.wav]

What if you had ignored JBL's manual and put the deck to its maximum UNDISTORTED output before setting the gain?

I was also curious on this. By setting the deck on it's maximum undistorted, would you get the same spot on the gain that the DD-1 detected? This would tell us just how accurate this JBL amp is at detecting distortion, but detecting anything after the deck that is....

[audiofanaticz]

apparently someone stole my 1st comment glory on youtube... lol

Sorry, better luck next time.

What if you had ignored JBL's manual and put the deck to its maximum UNDISTORTED output before setting the gain?

I was also curious on this. By setting the deck on it's maximum undistorted, would you get the same spot on the gain that the DD-1 detected? This would tell us just how accurate this JBL amp is at detecting distortion, but detecting anything after the deck that is....

As Steve already answered, possibly yes you should (in theory), but honestly that answer would be no for a couple reasons.

However the CD that came with the JBL amp only had 1 track and was around -15db (guesstimate since it was not labeled) so you wouldn't be able to get the overlap on the gain settings.

Also unless you have an oscilloscope, or a DD-1 to FIRST check the head unit for maximum un-clipped/distorted volume there is no way to tell where that volume should be prior to using JBL's "new technology" since the amp WILL NOT tell you where your head unit clips. So without a way to know of your radios max undistorted volume, you can only guess or follow JBL's instructions (which are flawed).

The owners manual just tells you to "Turn the head unit volume all the way up", and chances are unless your using a top of the line head unit from most companies the head unit will clip around 3/4 volume. Ive used my DD-1 on a few different Alpine CDA-105 head units already, and 2 of the 3 had a different max un-clipped volume. Sort of like an amplifier that comes with birth-sheets, not all of them say the same amount of power, and they tend to vary by a bit due to different variables in the parts.

The JBL amp is working slightly different than the DD-1.

The DD-1 is looking for 1% THD ((total harmonic distortion) that thing people claim they can hear and tune an amp 100% by ear)) when tuning the amplifier gain.

From my understanding the JBL built in gain setting device is operating somewhat similar to an clipping light on many amps, and is lighting up when the rail voltage is XX volts. Meaning that the light will light up no matter what once the rail voltage meets the desired voltage even if its clipped to death.

There has been a lot of videos done by various users of people with amps that have a built in clipping light lit up meaning the amp is clipping, but both DD-1 and even a Oscilloscope showing that the input and output of the amp is playing clean, even tho the clip light is on.

Edited April 28, 2012 by Audiofanaticz

[kirill007]

That amp looks very nice.

It has been a long time since end caps were used and i sometimes miss them.

I think it's a nice feature JBL has put into their amps, but like you said they should better say to turn your deck up to a few notches below max volume.

[Toby Ratcliffe]

Good video. I would recommend seeing a comparison in distortion using both the jbl, and dd-1 method, and then showing the waveform of the O-scope. That way you could possibly see distortion.

Then after that test is done, run a clamp test using both methods to see if there is any power advantages using the DD-1, like I would suspect there is.

[profundus-sanus]

From my understanding the JBL built in gain setting device is operating somewhat similar to an clipping light on many amps, and is lighting up when the rail voltage is XX volts. Meaning that the light will light up no matter what once the rail voltage meets the desired voltage even if its clipped to death.

There has been a lot of videos done by various users of people with amps that have a built in clipping light lit up meaning the amp is clipping, but both DD-1 and even a Oscilloscope showing that the input and output of the amp is playing clean, even tho the clip light is on.

yea man. thats exactly what it looks like. clipping light is lighting up when the voltage reaches a certain point. Since the deck was obviously clippin and the light was not conastantly lit*. no way it could actually be measuring any form of distortion.

good stuff!

at least jbl is trying haha. keep people from just runnning the gain maxxed out... although a -15db track is kinda on the sketchy side

Edited April 29, 2012 by profundus-sanus

[armykyle1]

Nice wright up.