Semi-Scientific SansAmp BDDI Analysis

[scotch]

I've had a love/hate relationship with my old BDDI for a long time. Sometimes I love how it sounds & sometimes I think it's just horrible! I'll never part with it though! (Obviously the problem is me, not the SansAmp!)

A big argument seems to exist as to whether the BDDI inherently "eats" mids or not. It's definitely easy to lose mids as you turn up the bass & treble controls. I just wanted to see what's going on inside the little black box when it's set "flat".

Please give me some input if I'm overlooking any important considerations. I already know that my "source" sound for this test isn't "real-world". But I think I'm still getting an accurate reading as to the eq coloration of the SansAmp. This all may have been a big waste of an hour!

Now, my methodology:
I imported a "pink noise" audio calibration test file directly into Pro Tools. The clip was about 10 seconds.
I then ran the unaltered pink noise out of an auxiliary send of my interface into the SansAmp, and then back into the interface as a separate recorded track. (note: I first ran a test using only a patch cable with no SansAmp to make sure that the new "recorded" track matched the original "imported" track - it was identical after matching the gain structure)
After mixing down the individual tracks from Pro Tools, I loaded both into Audacity where I normalized both tracks to match their overall volumes.
I then used Audacity to view their frequency curves.
The SansAmp BDDI was set with blend at 100%, level at 100%, and all other knobs as close to 50% as I could realistically accomplish.
Here's the results:

Pink Noise alone


Pink Noise through active SansAmp BDDI


I found it pretty interesting. I'll let everyone draw their own conclusions as it relates to the mid-freq controversy.

And yes, I obviously have way too much free time on my hands (it's January)!

[ihateusernames]

oh dear, this should be interesting!

[niftydog]

Don't worry about "real world" - the real world is impossible to duplicate. After all, there's how many thousands of different basses and pickups out there!? All that matters is that you test consistently - it's the comparative results that matter.

Nice work. Seems to me that there might be some benefit in a more detailed spectrum though. Especially since a lot of the interesting stuff for us bassists is below that first 3khz mark.

[scotch]

Originally Posted by niftydog

Don't worry about "real world" - the real world is impossible to duplicate. After all, there's how many thousands of different basses and pickups out there!? All that matters is that you test consistently - it's the comparative results that matter.

Nice work. Seems to me that there might be some benefit in a more detailed spectrum though. Especially since a lot of the interesting stuff for us bassists is below that first 3khz mark.

Yeah, I'd like to find software with more detailed spectrogram data from 3k to 40 hz. Any suggestions?

[niftydog]

Switching the scale to logarithmic instead of linear might reveal a bit more detail in the lower end of the spectrum. Other than that, it's hard to say what the other options are in that window, but perhaps there's a way of forcing Audacity to show you more of what you want. What other options are in those drop down menus?

[scotch]

thanks, niftydog - I figured out how to get better graphs....
(updated in original post)

[bassman251]

Try to reduce treble & bass to around 7 to 9'oclock position, then rerecord. There should be a increase in the mids. People always seem to miss this part when they always mention a mid scoop of the sansamp.

[scotch]

Originally Posted by bassman251

Try to reduce treble & bass to around 7 to 9'oclock position, then rerecord. There should be a increase in the mids. People always seem to miss this part when they claim a mid scoop of the sansamp.

7 to 9 oclock would be cutting the bass & treble significantly, so of course that would emphasize the mids.

In the test I set the controls for eq "flat" (that is, at their halfway position). I'm not claiming either way if the SansAmp is cutting mids, but letting the graphs speak for themselves.

In my personal use of the BDDI, I do reduce the bass & treble to try and get more mids. The problem is, the overall level of the DI goes too low and the sound engineer has to boost the level to the point of adding noise. I have the original model - I believe that the newer ones have higher output, possibly?

I appreciate your input, though. You're absolutely right as how to get more mids out of it.

[niftydog]

Sweet. That really shows the mid scoop nicely.

[Passinwind]

Originally Posted by scotch

Yeah, I'd like to find software with more detailed spectrogram data from 3k to 40 hz. Any suggestions?

I've been pretty happy with Rightmark. I also have and use Wavelab and True RTA, FWIW.

[ihateusernames]

The graph shows more of a crevice than a scoop, guess the sansamp scoops mid crowd was wrong all along

[keb]

Those graphs correspond with those posted in another, similar thread a few months ago (wish I could find it), showing the same notch in the 800-900Hz range.


Edit: Found that thread. (Note: I've actually gone back to using a Pod, using the GT2 set up to give a Tube Screamer-esque type of boost.)

[scotch]

Originally Posted by Passinwind

I've been pretty happy with Rightmark. I also have and use Wavelab and True RTA, FWIW.

Thanks!

Rightmark looks really cool. I'm not sure if I want to buy it as this is just a way to waste time for me. But maybe....

[greenboy]

I don't get the "real world" comments. The pink noise input represents ALL frequencies so when you look at what the output of whatever unit you've fed with pink noise, it shows exactly how that unit set the same way will filter bandwidth.

It'll filter ANY input signal the same way. If there is less content at whatever Hz using that unit with pink noise, there'll be less content at whatever Hz using this bass that bass or a mic'd kazoo.

I also don't get the comments about needing more detail. There's PLENTY of detail there to show how many dB difference there is at any frequency. The only way you could add meaningful detail would be to compare signals over time ; }

Could test at various input levels and settings to draw more conclusions yet, however.

[JanusZarate]

Looks like it's dropping somewhere between 750Hz and 850 Hz. Interestingly enough, the frequency center of the SansAmps's midrange is set at 750Hz.

I'd love to see what a mic'd SVT with a flat EQ (using a fairly flat mic, of course) would look like using the same pink noise and the same recording setup. Who knows - it might explain the choice in midrange scooping by Tech 21...

[Passinwind]

Originally Posted by scotch

Thanks!

Rightmark looks really cool. I'm not sure if I want to buy it as this is just a way to waste time for me. But maybe....

It's still freeware right now, the first commercial release is supposedly coming "soon". I mainly use it for signal/noise measurements and distortion measurements, both of which it does pretty well IME. I tend to use TrueRTA for spectrum analysis, because it works in real time if desired.

TB'er fdeck has a free SA app on his website too, BTW.

[SuperDuck]

I have access to an Audio Precision setup... if people really want super-detailed graphs I could probably make it happen.

[ihateusernames]

Originally Posted by MysticBoo

Who knows - it might explain the choice in midrange scooping by Tech 21...

Now that's one of the more intelligent conclusions posted when this topic comes up, again, and again, and then again.

Maybe this thread will put an end to all the debate and speculation, your suggestion would certainly help!

[JanusZarate]

One easy (but questionably reliable) solution would be for someone to use Ampeg SVX's SVT-CL emulation with an 8x10 cabinet, and run the pink noise test using it. They would have to try several different mic emulations for us to get the whole picture.

The drawback is that it really is just an emulation. But since Ampeg is so intent on touting it as the ultimate SVT software-based alternative, we might as well put it to the test.

The best solution would probably be an SVT-CL (maybe an SVT-VR... Tech 21 never specified which all-tube SVT they were trying to emulate) and an Ampeg 810E, miked with a high-end microphone - maybe an EV RE-20 or a Sennheiser MD-421? I'd have to double-check the curves on those to see what sort of bias we should expect.

For the record, I have an MD-421 Mk. II, but no SVT or 8x10 cab. I do have a demo version of Ampeg SVX, though.

At any rate, the lack of a mid knob on the BDDI is probably the bigger crime... but the real goal here is to compare the emulation to the real thing on a flat EQ setting.

[stedtale]

a dip at 800hz....icky...I <3 800Hz, best Hz ever