BFD | Electronic Equalization Devices

**brucek** · **09-16-07, 09:39 AM**

Fair enough, but I think it most important to test another unit.........

**jpmst3** · **09-16-07, 10:08 AM**

Agreed.

**Ilkka** · **09-17-07, 02:53 PM**

"Slartibartfast" over at AV Talk forum has confirmed my measurements. Our absolute levels seems to be slightly off but still the results show that the SMS-1 clips its RCA input rather easily. Also the ~0.5% - 1% THD already at lower levels is not very good performance.

http://www.avtalk.co.uk/forum/index.php?t=msg&goto=243382&rid=5915&SQ=1190058560#msg_243382

**Vaughan100** · **09-17-07, 04:53 PM**

Ag, no. I can't believe this ! I bought this thing last wednesday, and I'm really starting to regret the purchase. I'll give it my best shot tommorrow with the graphs (I'm off work) but the distortion levels are absolutely insane.

I still can't believe that Velodyne would release a product with such high distortion figures.

--Regards,

**brucek** · **09-17-07, 05:13 PM**

Quote:

I still can't believe that Velodyne would release a product with such high distortion figures

Do you feel you are hearing that distortion when listening?

brucek

**Vaughan100** · **09-17-07, 05:18 PM**

I may or may not. But that isn't the point right now. If the product has high distortion figures then that leads me to believe that there is a engineering fault.

Why would I want to keep something in my system that adds additional distortion at even low levels ? Right now I'm just very frustrated.

**Ilkka** · **09-17-07, 05:36 PM**

Quote:

brucek wrote:

Do you feel you are hearing that distortion when listening?

brucek

While 0.5% THD might not be audible but >5% definitely is, especially when it's 'electronic distortion', meaning it contains a lot of high order components.

Here's the spectrum of the SMS-1 THD at 50 Hz, 0 dBu. 50 Hz spike is the drive signal, all the other is distortion.

SMS-1

And here's the FBQ2496 at the same level. Notice the lower level of distortion.

FBQ2496

**Vaughan100** · **09-17-07, 05:44 PM**

Ikka, if I adjusted my sub level in AVR to -10 (it's lowest setting) would I be save from this input stage distortion on the SMS-1 ? Or could I still increase the sub level without fear of having added distortion entering into the mix ?

Thanks.

--Regards,

**Ilkka** · **09-17-07, 05:47 PM**

Quote:

Vaughan100 wrote:

Ikka, if I adjusted my sub level in AVR to -10 (it's lowest setting) would I be save from this input stage distortion on the SMS-1 ? Or could I still increase the sub level without fear of having added distortion entering into the mix ?

Thanks.

--Regards,

I wouldn't set it higher than -5. You can always raise the SMS-1 output level or the gain setting on your subwoofer (plate) amp.

**Vaughan100** · **09-17-07, 05:52 PM**

I'm really struggling whether I should keep the SMS-1 in my system or not. I probably haven't utilized it properly in my system yet although my graphs look pretty flat. I haven't messed around with polarity and phase on the SMS-1.

I wonder if I can even return it. I hate being in this situation.

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