# SMD DD-1 Product Review



## eddieg (Dec 20, 2009)

Hello everybody, 
My name is Eddie and I am located at Israel.
Not sure if this product was already reviewed over here but I would like to post my impressions any way as it is a fabulous little “Gizmo”.

Steve Meade and D’amore industries are mainly SPL oriented for the best of my knowledge but some of the measurements products and tools they offer today are easily qualifying for tuning SQ oriented audio systems as well. 

*What is the DD-1 product purpose? DD stands for Distortion Detector (1 is the version) *

So what does it measure? What does it do? And why it is “revolutionary” in compare to the old school methods of testing with an Oscilloscope and Multi-meter? 

The DD-1 is measuring THD, not Voltage RMS, not showing you sine wave clipping – neither does voltage nor clipping can tell you how much THD you have in your audio channel (in fact clipping comes after THD is audible for best of my knowledge).

The DD-1 alerts THD (distortion) detection once the THD is greater than 1% (no this is no a mistake, not 0.1 nor 0.01 but greater than 1%)

*Method of measurement* 

The DD-1 is provided along with a test CD that includes nine tracks: 
1.	40hz -0db attenuation
2.	1Khz -0db attenuation
3.	40hz -5db attenuation
4.	1Khz -5db attenuation
5.	40hz -10db attenuation
6.	1Khz -10db attenuation
7.	40hz -15db attenuation
8.	1Khz -15db attenuation
9.	PinkNoise

The device has a single input of type female RCA and that is to ease of use as you can connect the head unit RCA cable directly to the DD-1 (It can be any analogue source type).

But it is also provided with a Input converter from RCA female to two probes (plus and minus – red and black) so that you can directly connect it to speaker wire or to amplifier speaker outputs. 

*Process of testing*

Before I proceed here is a link directly to the product page:
SMD Distortion Detector DD-1 - SMD Distortion Detectors - SMD Tools - SMD Products

*Testing HU’s THD directly: *

Connect the RCA output of the HU directly to the RCA Input of the DD-1 using the RCA cable going towards the amplifier. 
If it is a speaker channel then use the 1Khz 0db attenuation track.
If it is a subwoofer channel then use the 40hz 0db attenuation track. 
Raise the volume of the HU until you see the correct frequency detected (either 40hz or 1Khz) and continue to raise it until detection LED is showing RED. 

Take the volume down a little until the distortion LED is turned off and you are set – now you know your maximal HU’s volume. 
Needless to say the HU’s audio settings – EQ, Boosts etc. should all be FLAT. 

*Testing HU’s THD through the amplifier – yes it is doable!*

The process of the test is identical to measuring HU’s THD directly connected to the DD-1 only this time you are to connect the probes to the amplifier’s speaker output and set the amplifier gain to the minimum thus you measure the signal as it goes out of the HU and through the amplifier on its minimal gain so that the original signal leaving the HU is minimally affected by the amplifier. 

*Testing the amplifier’s THD level*

Well now that we’ve found the HU THD threshold we can continue tuning the amplifier’s gain by connecting the DD1 directly to the speaker output.
Set the HU to its maximal unclipped/undistorted volume and play the test tone – as follows: 

1.	For SQ oriented speakers/subwoofer use the -5db attenuated tracks. 
2.	For a compromised system between SQ to a loud/SPL system use the -10db tracks.
3.	For a rather loud system use the -15db tracks.

In my case study I’ve used for the speakers a -5db at 1Khz track but for the sub when I’ve used the 40hz -5db track the system was too flat for my taste and did not perform well on the low and as I would like it to. 
So using the -10db 40hz track to tune the subwoofer channel and the result is spot on!

In my car audio case study I’ve got to the conclusion that I need a stronger mono block in order to set a steeper ration between my subwoofer to the front set from the first place – my subwoofer lacks power after fine gain calibration and if I try to add more it starts to distort in a way it gives away its location so – either stronger amp as the amplifier had reached a limit or this is something which is affected by the subwoofer box and for what it seems – it is distortion and change of amplifier should fix this. 

A picture of the DD1 which I’ve purchased: 










*As for versions: *

After the DD-1 there is the DD-1HV which stands for “high voltage” 
Now the DD-1 can measure between 1.2VRMS to 125VRMS which is “just” 15KWatts at 1ohm so it should fit any SANE person…
And after that comes the DD-1Plus which also gives you a voltage reading.
The price for a DD-1 is about 150 USD before shipment and taxes. 
As well check the CC-1 and the AMM products!

*Now for a few short pictures: *

1.	System tuned with subwoofer gains set to no distort on a 40hz -5db track.










2.	System tuned with subwoofer gains set to no distort on 40hz -10db track.










Take in mind that what you see is pink noise RTA reading – there is a big difference is subwoofer output between the two – in everyday music the difference is huge. 

3.	The DD1 detects 40hz frequency sine wave being played – no distortion detected yet. 










4.	The DD1 detects distortion at 40hz.










Thank you very much and hope you enjoyed the review.

Eddie


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## Audiophilefred (Oct 24, 2012)

Very nice review


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## WestCo (Aug 19, 2012)

It is an interesting tool.

Question is: A decent o scope is $60, bnib shipped. Would you rather do the scope or the dd-1? My answer is the the o scope, but I am not everyone. I have seen that the dd-1 can detect clipping, but o scopes were able to detect clipping sooner.

THD won't kill your drivers, but clipping will.


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## WestCo (Aug 19, 2012)

eddieg said:


> (in fact clipping comes after THD is audible for best of my knowledge).


No, this is not correct.

Clipping can be a cause of THD, but is not a result of THD. 

You could have a THD of >5% without having clipping.

If fairness, it is a very good device if you are trying to determine if a source unit is distorting or if it is a result of the amplifier.
This comes in handy when your having system problems and it is pretty simple to use. 

Setting gains conservatively is always the way to go. Maybe in SPL you'll want to push things to the limit.


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## sirbOOm (Jan 24, 2013)

Where can I get a $60 O-scope?!

I have a DD-1. I find setting gains with it does make a positive difference but you absolutely must start from the first point in the signal chain and I've found that occasionally mine will detect distortion before the signal Hz itself after an amplifier yet the source signal passes the DD-1 test just fine. When this occurred, each amplifier was brand new and I'd assume working fine. Most of the time it was an aftermarket HU sending signal through RCAs. Can't really use the DD-1 to detect "clipping" in an RCA if there would be any possible. Maybe I was doing something wrong.

When used a lot, it eats through 9V batteries and I wish the negative wire clip wasn't so smooth. Slips out of my hand every friggin single friggin time I try to connect it to a ground.


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## WestCo (Aug 19, 2012)

sirbOOm said:


> Where can I get a $60 O-scope?!
> 
> I have a DD-1. I find setting gains with it does make a positive difference but you absolutely must start from the first point in the signal chain and I've found that occasionally mine will detect distortion before the signal Hz itself after an amplifier yet the source signal passes the DD-1 test just fine. When this occurred, each amplifier was brand new and I'd assume working fine. Most of the time it was an aftermarket HU sending signal through RCAs. Can't really use the DD-1 to detect "clipping" in an RCA if there would be any possible. Maybe I was doing something wrong.
> 
> When used a lot, it eats through 9V batteries and I wish the negative wire clip wasn't so smooth. Slips out of my hand every friggin single friggin time I try to connect it to a ground.


Signstek Mini Pocket-Sized Handheld Digital Storage Oscilloscope ARM DSO Nano DSO201: Science Lab Oscilloscopes: Amazon.com: Industrial & Scientific

Price went up to $65

But that's pretty standard for those. Damn good tool.


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## WestCo (Aug 19, 2012)

sirbOOm said:


> Where can I get a $60 O-scope?!
> 
> I have a DD-1. I find setting gains with it does make a positive difference but you absolutely must start from the first point in the signal chain and I've found that occasionally mine will detect distortion before the signal Hz itself after an amplifier yet the source signal passes the DD-1 test just fine. When this occurred, each amplifier was brand new and I'd assume working fine. Most of the time it was an aftermarket HU sending signal through RCAs. Can't really use the DD-1 to detect "clipping" in an RCA if there would be any possible. Maybe I was doing something wrong.
> 
> When used a lot, it eats through 9V batteries and I wish the negative wire clip wasn't so smooth. Slips out of my hand every friggin single friggin time I try to connect it to a ground.


I've used it for rca diagnosis. It can be done.


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## eddieg (Dec 20, 2009)

Thanks guys! 

I also have a MDSO and I am using it as well, however, cliping usually would occur after noticable THD is evident. -> again for best of my knowledge for already I see I am to check my sources... 

The DD1 tells you when you have reached the mark of 1THD, most amplifiers would alert as soon as it is detected if they have THD or clipping controll, for example I have a Zed Audio Leviathan and indeed it detects "clipping" though it supposed to be THD for as much as I know before the DD-1 does. 

But as mentioned it takes for normal music up to 5%thd so it would be noticed by our ears and a subwoofer is much more forgiving and it can endure even 10% THD before it starts to be noticable by our ears. 

The DD1 give you a good starting point and it provides you with a better "knowing" of your system usable gain range. 

For 150 USD it worths every dime, cent, wha eva


By the way - I've bought my MDSO from DX.com at about 70USD - it works great but the back cover is useless and the USB port brok so I had to solder a new port my self - build quality sucks but it works great!

I've used the MDSO mostly up until to today first to diagnose If I have a signal entering crossovers - for example, in my dad's car the midbass speakers stopped playing and when I've dyagnosed the crossovers using the MDSO I've noticed that the signal is perfect, no clipping as well - so then I've done a battery test to the speakers and seen that they are operational so I've then figured out it was the wiring in the doors which had to be replaced. 


Using the DD1 - it is in order to find the thresholds of the HU and amplifiers for volume and gain and it works really great.


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