[basslik]

Originally Posted by USBnoGood

No. Why?

here you go, this was a unbiased test done with the help, and hard work from O.G Killa.
OK, so figured I'd just go ahead and post the answers along with the protools sessions for now and the spec sheet data can come later...



The BLA comparison experiment files:

https://rcpt.yousendit.com/738746161...8e85e0dca57610
(link expires 09/25/09) Protools Session files and photos.


For this test, to make it truly blind (or double-blind as some might say) I needed to not only record the two units in question, but record at least one "control" unit outside the realm of the other two. I decided to record two additional "control" units to try and give listeners some perspective as to what they were hearing, and also to help minimize any effects guessing or bias might play. The devices/setups under test...

1) Stock Digidesign 003+
2) BLA modded Digidesign 003+
3) Millennia HV3D 8 channel mic preamp into a Digidesign 192 IO
4) Millennia HV3D 8 channel mic preamp into a Prism ADA8

In order to try and rule out any variation in performances, and without a proper way to split one performance between all of the units under test and still adequately test the mic preamps of the units; I decided to record two takes of the same song on each device. This way, if people liked one of the takes, but not the other, it is a clear indication that the performance had a greater impact on fidelity than the interface. It would also show, if someone picked both takes from one unit as sounding best, that unit must have some noticeable sonic character that is distinguishable.

Also, to get the mics to match in level exactly from one unit to the next, I had to come up with a way to level match the mics. I tried using a cable tester's -50 mic level tone generator. But it didn't work, the interaction of the mic and preamp electrically changed the mic's level when I used the signal generator electrically to match the preamp's gain knobs. Although it did work for the Bass since the tone generator was going into the whirlwind DI box and then into the mic preamp. So I had to come up with a way that included the microphone.

I decided to use a metronome set to A440 and a ruler. By using the metronome I get a constant acoustic tone, and the ruler ensures that the tone's distance to the mics are the same for each unit. This gave me a steady peak reading on the protools meter. Then I matched that peak meter reading on all subsequent devices as I moved from one device to the next. I recorded one instrument at a time. Doing drums first to a scratch acoustic guitar track on all four units. Then bass on all four, guitar, piano, etc...

You might be wondering why there are 16 files instead of 8?... Because of the sonic differences in the mic/preamp match-ups, even with the preamps levels matched at 440Hz, there is a slight variation in RMS level of the entire mix from one unit to the next. The span was -24.2dB RMS being the lowest to -23.3dB RMS being the loudest. But, between the two takes on each unit the greatest difference was 0.1dB RMS and most had the exact same RMS level between the two takes. So I decided to leave the original files but also include gain adjusted files to "even the playing field" and see if the difference in level is what people liked or if anyone can actually hear the sound of the unit regardless of variation in RMS level of the mix.

The "gain adjusted" versions are all gain adjusted (using audiosuite gain) to -24.2 dB RMS. Some were dropped in level only 0.3dB while one (the loudest) was brought down by 0.9dB and two weren't dropped at all (yet I still label them gain adjusted, I ran audio suite on them with 0.0dB just to keep them concurrent with the other gain adjusted files). Any difference you hear between the gain adjusted and none gain adjusted of the same interface/Tk# is purely from a level change of 0.9dB or less.

So we have:

Millennia/Prism Takes 1&2 with and without gain adjustment.
Millennia/192 Takes 1&2 with and without gain adjustment.
Stock 003+ with and without gain adjustment.
And BLA 003+ with and without gain adjustment.

Below is the answer key with the order of these different files...

File Name Answer Key:
A - 192 Tk1
B - 192 tk1 (gain adjusted)
C - Stock 003+ tk1
D - BLA 003+ tk1
E - Prism ADA8 tk1
F - Stock 003+ tk2 (gain adjusted)
G - Prism ADA8 tk2 (gain adjusted)
H - Prism ADA8 tk1 (gain adjusted)
I - BLA 003+ tk2 (gain adjusted)
J - 192 tk2
K - BLA 003+ tk2
L - BLA 003+ tk1 (gain adjusted)
M - 192 tk2 (gain adjusted)
N - Prism ADA8 tk2
O - Stock 003+ tk1 (gain adjusted)
P - Stock 003+ tk2

Group Answer Key:
Group 1 - A, E, J, N (All HD, no gain)
Group 2 - C, D, K, P (All LE, no gain)
Group 3 - B, G, H, N (All HD, with gain)
Group 4 - F, I, L, O (All LE, with gain)
Group 5 - A, B, J, M (all 192, gain and no gain)
Group 6 - E, G, H, N (all prism, gain and no gain)
Group 7 - C, F, O, P (All Stock 003, gain and no gain)
Group 8 - D, I, K, L (all BLA, gain and no gain)
Group 9 - G, H, I, L (Prism vs BLA, with gain)
Group 10 - B, F, M, O (192 vs stock, with gain)
Group 11 - F, G, H, O (Prism vs stock, with gain)
Group 12 - B, I, L, M (192 vs BLA, with gain)

My own thoughts... I like the sound of the stock 003+ for drums, but I liked the sound of piano and guitar on the Modded 003+. We also noticed, most likely to do impedance matching, that the modded 003+ had an audible amount of additional sustain on the piano (TLM170 mics). It was immediately noticed by Dr. Ford sitting at the piano listening in headphones and I noticed it as well. It seemed the piano in the BLA mod mic preamps seemed to last longer and you can hear the tails of the notes last longer.

For me there is no clear winner. I can hear subtle tonal differences between the two units. But for me to say one is definitively better than another would be lying. It's really up to all of you, listen to the multi-tracks and see if you can hear differences and decide for yourself which one you like the sound of best.

One thing I will say though... comparing the 003 (stock and modded) to the 192 and ADA8 I didn't hear a huge difference either... and for this type of music in the blind listening I was leaning towards a preference of the 192 out of the 4, not the Prism!! But the difference between ALL four units was very small and I must say I feel that changes in the performance really made a larger impact on the sound than the mic preamps and converters did. Which just goes to show, all those people that say, "to get that sound you need to get that musician in that room with that specific instrument" really are speaking the truth.

And Maddawg was asking me "how did you get that kick drum sound?!?!? I really like it! I can't get my kick drums to sound like that" Come to find out I was using the same mic in the kick he has (Beta52), and I was using his 003+ Modded unit!!! The difference was the in the room (and sound in the room mics), the tuning of the drum, and the way I play the kick drum. The sound had nothing to do with the mic, preamp or converter... In the end it's all about acoustics.

Also, from a user's perspective. I could notice a difference in adjusting the gain of the preamps. Since I was trying to match the gain from one unit to the next to the exact tenth of a dB, I really noticed how smooth the gain increase was on the BLA mod. The knobs on the stock unit, while turning them, the gain would jump up at spots and then not increase much at all in other spots. The gain increase wasn't very linear as I turned the knob. Once I got close to the target level, it was much more work getting the exact level, one tiny movement of the knob might increase by 3dB, then a tiny movement down might only drop by 0.5dB, then another tiny movement down would drop it by 1dB then a tiny movement up would add 0.2dB, etc...

With the BLA mod the increase in level was uniform/linear as I turned the knob (no jumps) and a tiny little movement always resulted in a very small change in level (0.1 to 0.3dB) as one would expect. Is this really a big deal? Not really... most people will just turn the knob until the level sounds good and then move on. But it was something I really noticed a lot.

Also as final note... you'll notice there is a Vocal track in each one that I decided not to include in the mixes. I recorded that really quick at the end of a session and I didn't have the metronome with the A440 with me, so I couldn't level match using that technique. I tried to "ear it up" as best I could. But upon listening later, the levels weren't exactly matched between all the units adn the overall level differences between one unit and the next made the vocals on one sound dramatically better on one than another and it wasn't a fair comparison between the units. So I muted it. But its still in there if you want to hear it.

And you'll notice there is a master fader on each one that might have a slight gain adjustment on it. This was to make sure the outputs of each unit were electrically matched. Since the 003's don't have analog trim pots on them, I decide to use a master fader across all four units. I played a -18dBfs sine way out of each unit, (you can see it in the session, it is an aux track labeled "cal") into the prism and adjusted the output from the master fader so that the input into the prism was -18dBfs. I also recorded that test tone with each unit for you all to check/compare.

So that's it. I still don't have the spec sheet reports yet. But in talking with the guys, it might still be a few days before I get them... so I figured I'd just post all this stuff up since someone started asking about it. Enjoy and I'll post the specs when I get them!