OB6 vs REV2

[AlainHubert]

Just a small audio demo of the same patch (first programmed on the OB6 and very carefully recreated on the REV2 taking into account the differences in both machines), with only the onboard reverbs respectively.

I think it's pretty clear how good the OB6 sounds...

I like my REV2, but I LOVE my OB6.

https://soundcloud.com/thealien666/ob6-rev2

[Sleep of Reason]

Perhaps it's different in person, but the only thing clear to me is that the REV2 has a ton of advantages in functionality with negligible difference when recorded, especially when it's going to be sitting in some mix. 

[DavidDever]

Perhaps it's different in person, but the only thing clear to me is that the REV2 has a ton of advantages in functionality with negligible difference when recorded, especially when it's going to be sitting in some mix.

The knob-per-function approach of the OB-6 (both keyboard and module) is great, but one quickly discovers that the serious modulation capabilities of the REV2 (and its predecessors) are sorely lacking.

Though I'm not holding my breath, I would love to see a full-featured, discrete VCO-based instrument from DSI with a complete mod matrix, a la the Oberheim Matrix-12 / Xpander.

I've got a Matrix-6 and Matrix-1000 which, while lacking the knobby immediacy of the REV2, can take one to places in OB territory with its capable mod matrix that the OB-6 cannot - that said, the tone of the OB-6 clearly makes up a good portion of the difference!

[AlainHubert]

I'm not holding my breath either for such a "perfect" polyphonic synth, combining a superb analog sound like the OB6 or P6, AND as many features as the REV2 modulation wise, from DSI.

The Matrix-6 (which I also own) does offer a lot of modulation possibilities (although a pain to edit without a controller), but it sounds somewhat dull compared to an OB6 thanks to its CEM3396 (basically the same chips used in the REV2 which also pales a little in comparison to the OB6). However, the REV2 offers a lot more voices (the 16 voice model).

BTW the Oberheim Matrix-12/Xpander didn't use discrete VCOs (like in the P6 and OB6 from DSI) but rather the famous CEM3340, which also sounded bloody great. Much nicer than the DCOs of the CEM3396/PA397/DSI120, IMHO.

[DavidDever]

BTW the Oberheim Matrix-12/Xpander didn't use discrete VCOs (like in the P6 and OB6 from DSI) but rather the famous CEM3340, which also sounded bloody great.

Actually, the Matrix-12 and Xpander used a dual-VCO CEM 3374 per voice*. The filter/VCA IC (CEM 3372) is the same as used for the Sequential Prophet-T8 and -600 (both of which use CEM 3340 VCOs, which are now available in Rev G form).

My remark about the discrete VCO was that it makes more manufacturing sense (having the existing implementation from the OB-6 and/or Prophet-6) to use that optimized design, rather than an off-the-shelf oscillator IC.

* - availability of which, compared to the CEM 3340, is one of my primary reasons for not pulling the trigger on one.

[AlainHubert]

I stand corrected, CEM3374 indeed inside the M12 and Xpander.
I agree with you that producing a 16 voice OB6 (possibly called OB16 ?) with the flexibility of a REV2 would be really fantastic, and nothing in the current design prevents this from happening. DSI only have to put 16 DIMM sockets to receive as much OB6 voice cards in there, followed by a beefed up software to control them. The current MCU/DSP technology is more than able to deal with that.

 

[Sleep of Reason]

Again, the DCO vs VCO debate is overplayed to me. I would personally much rather hear a REV2 with some SSM based filter, I.E. a REV3. Let's get a reverse P5 Rev-style debate going just to see what people say in that situation.

[DavidDever]

Again, the DCO vs VCO debate is overplayed to me. I would personally much rather hear a REV2 with some SSM based filter, I.E. a REV3. Let's get a reverse P5 Rev-style debate going just to see what people say in that situation.

That could be interesting, for sure.

To me, the DCO vs. VCO thing is all about pitch relationships, to which end you can also throw octave-divider based tone generators into the mix. Sonically, on a per-voice basis, it's not as conclusive a difference (all things being equal).

[AlainHubert]

Also the nature of the ramp generator design inside the CEM chips (VCOs or DCOS) is very different from some other discrete components VCOs. The waveform of a Minimoog oscillator is very different from the one from a CEM3396. Actually, the OB6 is very similar with a pronounced curved slope at low frequencies, and lots of high harmonics too.

But I agree that the main culprit for the CEM3396 slight "harshness" is probably the filter, which distorts the sound somewhat, even though the datasheet says, and I quote:"Special care has been taken in the design of the filter and VCAs to insure low intermodulation distortion...". Notice how they said "low distortion" which means it can still be there and noticeable.
I'd be willing to bet that the SEM inspired filter of the OB6 has an even lower distortion level...   

Let's face it, some early CEM chips sounded really great. Some later ones, not so great. Hence the audible differences between them.

[LoboLives]

Also the nature of the ramp generator design inside the CEM chips (VCOs or DCOS) is very different from some other discrete components VCOs. The waveform of a Minimoog oscillator is very different from the one from a CEM3396. Actually, the OB6 is very similar with a pronounced curved slope at low frequencies, and lots of high harmonics too.

But I agree that the main culprit for the CEM3396 slight "harshness" is probably the filter, which distorts the sound somewhat, even though the datasheet says, and I quote:"Special care has been taken in the design of the filter and VCAs to insure low intermodulation distortion...". Notice how they said "low distortion" which means it can still be there and noticeable.
I'd be willing to bet that the SEM inspired filter of the OB6 has an even lower distortion level...   

Let's face it, some early CEM chips sounded really great. Some later ones, not so great. Hence the audible differences between them.

Something that I learned recently is the P6 oscillators seem to be naturally driving the filter hard If they are fully cranked. The trick is to decrease them to roughly 50 to 70 percent and then decrease the amp envelope to about 60. Bring up the master volume and adjust the overall volume. I’ve noticed a considerable difference by doing this. The sound is warmer and a bit more full sounding. It eliminates the harshness and makes the overall tone more akin to the P5. In fact a lot of the Prophet 5 presets John Bowen programmed into the P6 actually have the oscillators and amp envelope down!

[MPM]

I couldn’t hear any difference in that sound comparison in the first post at all.  Tried two different headphones too.

Anyway, in the short time I’ve been creating patches on the OB6, I’ve then tried to make some of them on the Rev2 just to observe the similarities. Finding that I’m getting closer results on the Rev2 if I use it’s 4pole setting, which is a bit odd.
Also finding the OB6 a bit more consistent when using narrow pulse wave. On the Rev2 it’s a bit random.

Anyway. I’m quickly realising what preferences I have for each, and both are definitely keepers.

[AlainHubert]

I couldn’t hear any difference in that sound comparison in the first post at all.  Tried two different headphones too.

Anyway, in the short time I’ve been creating patches on the OB6, I’ve then tried to make some of them on the Rev2 just to observe the similarities. Finding that I’m getting closer results on the Rev2 if I use it’s 4pole setting, which is a bit odd.
Also finding the OB6 a bit more consistent when using narrow pulse wave. On the Rev2 it’s a bit random.

Anyway. I’m quickly realising what preferences I have for each, and both are definitely keepers.

Soundcloud audio compression doesn't help matters, but there is still a very slight difference nonetheless. The OB6 has a little more high end content.

You can download the uncompressed audio version (.wav format) here:
https://www.dropbox.com/s/4ttgg87ohw5sn6d/OB6-REV2.wav?dl=0

[discorules]

Just a small audio demo of the same patch (first programmed on the OB6 and very carefully recreated on the REV2 taking into account the differences in both machines), with only the onboard reverbs respectively.

I think it's pretty clear how good the OB6 sounds...

I like my REV2, but I LOVE my OB6.

https://soundcloud.com/thealien666/ob6-rev2

Cool but would be VERY nice if you could make a video with a step-by-step comparison in the patching process. I'm an owner of a Rev2 and been thinking seriously in get an OB6 also. But the price and (apparently) poor construction quality (plastic knobs ?) are holding for while.

[MPM]

...But the price and (apparently) poor construction quality (plastic knobs ?) are holding for while.

The plastic knobs are actually very solid and Larger than the Rev2’s. I’m thinking about asking DSI if they’ll sell them so I can put them on my Rev2.

[AlainHubert]

I’ve seen reports of wobbly knobs on the OB6, but on my unit (module version) they’re very stable and feel solid. I’ve had my unit for about a year now without any issues with the plastic knobs.

[discorules]

I’ve seen reports of wobbly knobs on the OB6, but on my unit (module version) they’re very stable and feel solid. I’ve had my unit for about a year now without any issues with the plastic knobs.

Thanks for the info. If you had to explain in a few phrases why do have you got an OB6 already having a Rev2, what would you say?

[AlainHubert]

Thanks for the info. If you had to explain in a few phrases why do have you got an OB6 already having a Rev2, what would you say?

You're welcome. 
Because both machines are very good at what they do. One offers instant gratification and the other offers tons of possibilities modulation wise. And although it's possible to get both to sound very close, not without a little work, they also differ enough to justify having both (but that's only my personal opinion, based on my particular needs and preferences).

BTW, it was the other way around; I got the REV2 after I already had the OB6.

[discorules]

I couldn’t hear any difference in that sound comparison in the first post at all.  Tried two different headphones too.

Anyway, in the short time I’ve been creating patches on the OB6, I’ve then tried to make some of them on the Rev2 just to observe the similarities. Finding that I’m getting closer results on the Rev2 if I use it’s 4pole setting, which is a bit odd.
Also finding the OB6 a bit more consistent when using narrow pulse wave. On the Rev2 it’s a bit random.

Anyway. I’m quickly realising what preferences I have for each, and both are definitely keepers.

Soundcloud audio compression doesn't help matters, but there is still a very slight difference nonetheless. The OB6 has a little more high end content.

You can download the uncompressed audio version (.wav format) here:
https://www.dropbox.com/s/4ttgg87ohw5sn6d/OB6-REV2.wav?dl=0

After listening to the WAV example i'm seriously rethinking about my wish to get an OB6 already having a Rev2. The patches sounds almost the same, the OB6 has more high end for sure but that's all... I really don't know if such a thing justify the us$ 3000 price tag, at least in my case.

I've watched a lot of OB6 videos and usually the demos are way more into the timbral spectrum i like most (70s disco / 80s synthpop), sounds i could not or have a lot of struggle to replicate on my Rev2. But now i'm wondering the problem is more about the synthesizer operator (me) than the synthesizer itself... 

[MPM]

I've watched a lot of OB6 videos and usually the demos are way more into the timbral spectrum i like most (70s disco / 80s synthpop), sounds i could not or have a lot of struggle to replicate on my Rev2.

I’d say I only got a “thin impression” of the OB6 (and Rev2) on YouTube etc.
It was hearing the OB6 live on stage that grabbed me. And I could never emulate that sound on a Prophet 08 or Rev2, Nord Leads or Moogs.
I tried to get there stacking A+B layers on the Rev2 and came close on some patches, but it got too tricky or fell apart when I introduced other modulations.

On my 2nd trip to try the OB6 in the store, I hit sequencer start, and stepped from preset 000 all the way to 499 with the sequencer running.
When a patch interested me I took note of a few things, asking myself if it could be replicated in Rev2:

# was VCO2 on Low Freq? If so, what was going on in X-MOD?
# in X-MOD was NORM->BP or VCO1 lit up?
# was FILTER MODE lit up in X-MOD or LFO or Aftertouch?
# I turned the Filter mode pot to find where it was set. Was it on BP? If not LP, where?
# were 2 Effects being used simultaneously, + Distortion?

I knew it would be a challenge to get patches with those exact parameters on the Rev2 in a single layer, but went home to try it out even with two layers.
On return, ignoring the OB6 patches which sounded similar to the Rev2 (or Nords/Moogs), I went back to the ones I loved having the above # settings in action (Lucky I wrote the patch numbers down!).
So I messed around with those to see where it’d take me, and sure enough I walked out with an OB6.

In a nut shell. The Rev2 can make lots of similar voices to the OB6, and vice versa. It’s a question, and an exercise, to determine if the voices you struggle to get on the Rev2 are indigenous to the OB6 by virtue of its unique parameters.
As for the price vs. voices and programming, that's down to you.

And FINALLY watch this Casio do an OBXa patch and question life itself

https://www.youtube.com/watch?v=yKuT0UpAxIc


.

[Shaw]

I’ve owned and played both, and I still have the OB-6.  My thoughts:  It’s all in the filter. The Rev 2 can do 2-pole, but that’s a far cry from the variation available from the OB-6 state-variable filter.


There are other differences as well, but the difference in filters is the first place to look for the difference in sound between these two synths.


My 2¢.