# Velodyne SMS-1 Mic ?



## mikejl46

I purchased a Velodyne SMS-1. It includes a mic that is not the original. Its a Samson R11. Will this mic work?

Dose any one know what mic the SMS1 uses? I would like to purchase the original mic, but not sure what model it is.

Thanks,

Mike


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## Wayne A. Pflughaupt

You should probably contact Velodyne. I believe the stock mic is a Behringer ECM8000, but they all have somewhat different response. If Velodyne did things right, each SMS and its specific mic were a calibrated package, and you won’t get the same results with a substitute mic.

Regards,
Wayne


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## mikejl46

Wayne A. Pflughaupt said:


> You should probably contact Velodyne. I believe the stock mic is a Behringer ECM8000, but they all have somewhat different response. If Velodyne did things right, each SMS and its specific mic were a calibrated package, and you won’t get the same results with a substitute mic.
> 
> Regards,
> Wayne


Thanks, Wayne

I contacted Velodyne today and the mic is a Behringer ECM8000. They can sell me one for $70.00. I can find the Behringer ECM8000 new on ebay for $54.00. Is it going to make any difference if I buy the one on Ebay?


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## mikejl46

I received an email from Velodyne and he said any Behringer ECM8000 mic will work with the SMS 1, in case someone else needs to know.


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## Wayne A. Pflughaupt

Sure, any mic will work, but how well? This graph from Cross Spectrum shows the variance in response between a significant number of ECM8000 mics.









Back in the ’90s I bought some AudioControl 30-band (1/3-octave) equalizers, and the company’s “matching” real time analyzer (RTA). If you’re not familiar with old-styled hardware analyzers, they came with a “calibrated” mic that you’d place at the listening position. The RTA would generate a broadband pink noise signal from your system’s speakers, and the mic would pick up the signal and give a readout of your response on its LED display. You can see the RTA in the center stack of this picture.







​

At the time, I thought it was a curiosity why the RTA cost over $100 more than the 1/3-octave EQ did. Didn’t really make sense – after all, it’s just a LED display, right?

Well, some years later I learned why. The situation with the RTA is “accuracy.” Naturally, an instrument like this is only good if it’s accurate. In a perfect world, a mic with perfectly-flat response would be included with the RTA. Naturally, this isn’t economically feasible, because the cost of such a mic would double or even triple the cost of the RTA. So, they use lower-grade mics instead. 

But what you get with inexpensive “lower grade” is variation in response from one sample to the next (see graph above). So, the solution for that: Each RTA must be calibrated to compensate for the response of the _particular mic_ it’s shipped with. This means each RTA that left the factory required a hands-on calibration and tuning by a technician. Well, that’s man-hours spent above and beyond the cost of merely manufacturing the hardware. And that’s why the “nothing but an LED display” RTA cost more than its companion equalizer. (Naturally, this is merely a variation of REW's use of a mic calibration file to "adjust" the program to compensate for the mic's deviations from flat response).

As I mentioned in my previous post, if Velodyne “did I right” they did the same calibration process with each SMS-1. If that’s the case, (and admittedly I don’t know if it is), then a replacement mic won’t be as accurate as the mic it was originally shipped with. The Cross Spectrum graph should be proof enough of that.

I really wish you had asked us about this before you spent the money on an SMS with a “replacement” mic (and especially something the previous owner obviously just randomly picked up).


Regards,
Wayne


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## tcarcio

I would call velodyne and ask them if they calibrate each mic to each unit and if they do then send the unit back to them and have them cal a mic to your system so you can be sure your getting correct results. If the cost is too high then you might have to just take the loss if the seller doesn't want to refund your money.


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## mikejl46

I sent them an email asking them asking them if they calibrate each mic to each unit. I don't see how they could not or all the SMS 1 units would be inaccurate. Should hear from them today. 


What if I was to run the SMS 1 and get as flat as possable, then run some test tones with Radio Shack meter to see how far off I am and then make corrections. Would that work?


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## tcarcio

You could try that but then the reason for having the SMS is mute. Also I don't know how accurate the RS meter is for that type of thing either.


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## mikejl46

tcarcio said:


> You could try that but then the reason for having the SMS is mute. Also I don't know how accurate the RS meter is for that type of thing either.


I'm pretty much stuck with this thing now. I won't sell it and give someone else the problem I have now, so I some how need to make it work. It is a Parametric EQ and once I get things flattened out, I will probably never touch it again.

Hopefully I can make it work.


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## Wayne A. Pflughaupt

You're an honorable guy not to want to pass this thing on to some other unsuspecting soul, Mike. :T

As tcario noted, the SMS-1 is supposed to be a better and more efficient and faster method than using test tones and the SPL meter, but you can get acceptable results using the meter and manual plotting response, as this fellow has. It was common practice before things like REW came along. The meter’s response basically tracks the C-weighting curve. If I recall, the Excel workbook you can download in the BFD Guide has compensation for the meter’s natural low-freq roll out built-in. If not, you just add the correct adjustment dB figure to the meter’s display. Post some of those excel graphs and we'll be happy to help you determine the parametric filters you'll need to program into the SMS-1. We'll make this work. :T

Regards,
Wayne


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## mikejl46

Wayne A. Pflughaupt said:


> You're an honorable guy not to want to pass this thing on to some other unsuspecting soul, Mike. :T
> 
> As tcario noted, the SMS-1 is supposed to be a better and more efficient and faster method than using test tones and the SPL meter, but you can get acceptable results using the meter and manual plotting response, as this fellow has. It was common practice before things like REW came along. The meter’s response basically tracks the C-weighting curve. If I recall, the Excel workbook you can download in the BFD Guide has compensation for the meter’s natural low-freq roll out built-in. If not, you just add the correct adjustment dB figure to the meter’s display. Post some of those excel graphs and we'll be happy to help you determine the parametric filters you'll need to program into the SMS-1. We'll make this work. :T
> 
> Regards,
> Wayne


Thanks, Wayne

I feel much better about this now, and feel more like I can make this work using the SMS 1. I'm waiting on an email from Velodyne to see what they have to say about the ECM8000 mic. Either way I'm going to pick up a ECM8000 mic and go for it.

I'll be back.

Thanks again,

Mike


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## mikejl46

Here is what my sub looks like using the Excel Workbook for Radio Shack Model 33-2050 that I have.










Measurements from Radio Shack meter

20.0, 69
22.0, 67
25.0, 75
28.0, 79.5
31.5, 84
36.0, 88.5
40.0, 92.5
45.0, 86
50.0, 82
56.0, 79
63.0, 90
71.0, 88
80.0, 82
89.0, 75
100.0, 74
111.0, 57
125.0, 50
142.5, 50
160.0, 50


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## Wayne A. Pflughaupt

What kind of sub is this? That’s a pretty severe spike at 40 Hz; it’s pushing the limits of what can be reasonably equalized (more on that topic here). Do you have any other placement options?

Regards,
Wayne


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## mikejl46

Wayne A. Pflughaupt said:


> What kind of sub is this? That’s a pretty severe spike at 40 Hz; it’s pushing the limits of what can be reasonably equalized (more on that topic here). Do you have any other placement options?
> 
> Regards,
> Wayne


It's a Adire Rava sub. I have it back in a corner. I may be able to move it to one other location.

I was messing around with REW and imported the Freq readings from the radio shack meter.

Would these setting work to flatten it out some, or doesn't it work that way.


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## Wayne A. Pflughaupt

mikejl46 said:


> Would these setting work to flatten it out some, or doesn't it work that way.


Sure, that would be a good place to start.

Regards,
Wayne


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## mikejl46

Here is the email from Velodyne.


Hi Mike,

It does not matter if you have the original ECM8000 Behringer mic . It will work . 

Jeff Davis
Product Support / Technical Assistance


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## mikejl46

The SMS-1 worked out ok without the original mic. I was able to take down the high spots just fine. 

Here is a graph of the before and after.










Thanks,

Mike


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