First time graph - please critique!

**Jarin** · **03-12-08, 10:26 PM**

Ok, been messing around with REW and the new analog RS SPL meter for a few days now. I have a SVS dual 12" sub, and in front of it the Velodyne SMS-1 processor. I let the Velodyne SMS-1 do its thing, and then set up REW to check out a graph. I'm currently using a 24-bit Live SB USB sound card, laptop, and the new analog RS meter and loaded the new analog values for the meter.

I think I've done everything pretty close to correct. I had to jack up my receivers volume a bit above what I thought was 75db to get REW to not give me a 'level too low' message, but I guess that's ok.

Anyways, here it is...thoughts? (sub+mains, receiver crossed over at 80hz, SVS sub tuned to 20hz.)

J

**brucek** · **03-12-08, 11:08 PM**

It looks like you left your mains on for the measurement? Hard to comment without knowing what the crossover is you're using and a graph of the sub alone.

brucek

**Wayne A. Pflughaupt** · **03-12-08, 11:20 PM**

I wouldn’t mind seeing a “before” graph to gauge how well the SMS-1 “does its thing.”

Regards,
Wayne

**Jarin** · **03-13-08, 12:19 AM**

Quote:

brucek wrote:

It looks like you left your mains on for the measurement? Hard to comment without knowing what the crossover is you're using and a graph of the sub alone.

brucek

Yep, sub+mains using the receivers 80hz x-over, sub tuned to 20hz. Interesting that the DB level is seemingly a bit low, both my meters were showing higher levels than the graph shows, although it was consistent. I must have calibrated the SPL level wrong or something.

I'll re-calibrate and retry tomorrow and post new graphs with sub-alone before SMS-1 calibration, and sub-alone after the SMS does its thing.

Amazing piece of software, real nice stuff.

J

**Jarin** · **03-13-08, 01:41 PM**

Ok, I re-did things today sub-only.

I did a factory reset on the SMS-1 unit and ran a test:

And then I let the SMS-1 auto-eq for a bit, and ran another test:

Hmm, not sure it's improving anything much really.

J

**Wayne A. Pflughaupt** · **03-13-08, 02:50 PM**

So you’re saying that this is “before and after” with the SMS?

Regards,
Wayne

**Jarin** · **03-13-08, 03:06 PM**

Quote:

Wayne A. Pflughaupt wrote:

So you’re saying that this is “before and after” with the SMS?

Regards,
Wayne

Yea, first graph taken just after a factory reset, to clear anything I might have set on it - so basically, no EQ. The second graph after just a basic auto-eq. I didn't delve into any of the bells and whistles whatsoever on it. Just an auto-eq and save to default preset.

Historically, since I've started to mess with the SMS, I've seen that peak between 50 and 60hz from its microphone and real-time graphing, and now again with the REW graphing and SPL meter. I've not been able to EQ that peak with any further SMS modifications.

J

**brucek** · **03-13-08, 03:35 PM**

Yeah, well I suppose the after response of the sub only is a bit better, but my concern is the rather poor integration of the mains and sub in your initial plot. It appears quite poor.

It is hard to judge whether the mains + sub plot is a result of poor phase adjustment causing the dip around the crossover, or are the mains not capable? It would be interesting to see a mains only....

brucek

**Jarin** · **03-13-08, 03:52 PM**

Quote:

brucek wrote:

Yeah, well I suppose the after response of the sub only is a bit better, but my concern is the rather poor integration of the mains and sub in your initial plot. It appears quite poor.

It is hard to judge whether the mains + sub plot is a result of poor phase adjustment causing the dip around the crossover, or are the mains not capable? It would be interesting to see a mains only....

brucek

I see what you mean - that area between 60 and 100 does appear low, correct? I'll do a mains only as well and see what that shows, I'm curious myself now.

They're Def Tech 7002's (12" internal powered driver for the low end). Crossed over at 80hz. I can definitely play with phase, and various other items and see what happens.

Does the sub alone look horrible? I've no room treatment at the moment (on the list of upcoming things to do).

Appreciate all the help. This is certainly an interesting hobby. :-)

J

**brucek** · **03-13-08, 04:01 PM**

Quote:

Does the sub alone look horrible?

Absolutely not. It looks quite smooth and quite capable. Yeah, you have a bit of a peak at ~55Hz - no big deal. That's a nice subwoofer response.

If you establish that your mains are capable and track a proper target, then the problem is integration from phase or time. The new RTA features of REW will help there as you can watch the screen (with the mains + sub showing) and adjust phase (or time) in real time to see the results..

brucek

**Jarin** · **03-13-08, 04:08 PM**

Quote:

brucek wrote:

Absolutely not. It looks quite smooth and quite capable. Yeah, you have a bit of a peak at ~55Hz - no big deal. That's a nice subwoofer response.

If you establish that your mains are capable and track a proper target, then the problem is integration from phase or time. The new RTA features of REW will help there as you can watch the screen (with the mains + sub showing) and adjust phase (or time) in real time to see the results..

brucek

Nice! I was hoping there was an RTA feature (haven't dug that deeply yet). The SMS-1 has that, it runs the test sweep continuously and the adjustments you make show up real-time. So REW can do that as well?

J

**brucek** · **03-13-08, 04:37 PM**

Yep................set up your levels, and select the Spectrum tab, select RTA (~ 1/24th octave, 65536 FFT with a Hann window) and run the sig gen with Pink Periodic noise and press the red button.............

**Jarin** · **03-13-08, 08:45 PM**

Quote:

brucek wrote:

Yep................set up your levels, and select the Spectrum tab, select RTA (~ 1/24th octave, 65536 FFT with a Hann window) and run the sig gen with Pink Periodic noise and press the red button.............

Wow, that's nice! I could easily see phase come into play with my mains vs. sub as I turned the knob real-time. Here's the new graph with sub about 150 degrees out of phase with the mains Def Tech's.

What do you think now...? Not sure about that dip around 120 tho!

J

**brucek** · **03-13-08, 09:15 PM**

Quote:

What do you think now...? Not sure about that dip around 120 tho

Yeah, that's a lot better. The dip at 120 is fairly sharp -should be fine.

brucek

**Jarin** · **03-13-08, 09:33 PM**

Quote:

brucek wrote:

Yeah, that's a lot better. The dip at 120 is fairly sharp -should be fine.

brucek

It's all worth those small moments when you can pop in a new DVD (Pink Floyd - Pulse, just came today), and actually enjoy it without having to fiddle with anything! Pretty rare nowadays it seems...

J

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