# REW measurements of bass management of Emotiva UMC-200 pre/pro



## andy_c (Aug 8, 2006)

Hi all,

In the past, I have heard about some quirks in the bass management of the now-discontinued Emotiva UMC-1, including Sonnie's review of it. I recently bought a UMC-200 for a two-channel setup with subs. Because the UMC-200 is the successor to the UMC-1, I wanted to check out the bass management with REW measurements to make sure there weren't any quirks.

My measurement setup is as follows:

Computer sound adapter: Tascam US-144MkII
"Use loopback as timing reference" REW setting used
Loopback from Tascam right-channel analog output to right-channel analog input
Tascam S/PDIF output to UMC-200 S/PDIF input 1 using S/PDIF left channel in REW software
Analog output of UMC-200 (manually switched between left channel and subwoofer out) to left-channel analog input of Tascam

UMC-200 configuration as follows:
S/PDIF input 1
Stereo mode
Front speakers set to SMALL
Crossover frequency 100 Hz
High-pass slope 24 dB/oct
Subwoofer set to ON
Low-pass slope 24 dB/oct
All other speakers set to NONE

The first thing I did was a measurement of the left channel output from 10 Hz to 1000 Hz. I did this for the maximum left-channel distance setting (minimum delay) of 32.8 feet. I measured again with a left-channel distance setting of 0 (maximum delay). I plotted the frequency response, which was as expected: 6 dB down at 100 Hz (Linkwitz-Riley 4th order high-pass filter, not shown). Then I plotted the group delay vs. frequency for each of these two distance settings. This is shown below, only down to the crossover frequency of 100 Hz, since the group delay gets noisy because of the rolloff of the high-pass filter below 100 Hz. The group delay is not constant, due to the nonlinear phase shift of the crossover high-pass filter.










The group delay at 1 kHz and 32.8 foot distance setting is 3.2 msec. For the 0 foot distance setting, it is 32.3 msec This is a difference of 29.1 msec. To compute what it should be, the speed of sound at 20 deg C is 1126 ft/sec, or 0.888 msec/ft. Then 0.888 msec/ft * 32.8 feet = 29.1 msec. The measured difference in delay of 29.1 msec is right on the money and exactly as it should be.

Next, I measured the subwoofer out for the two different subwoofer distance settings of 0 and 32.8 feet. The results are shown below. I've restricted the maximum frequency, again to avoid noise due to reduced signal level from the rolloff of the low-pass section of the crossover.










Yes, both measurements are present in this graph. At first, I thought I had made an error, but I double- and triple-checked it. The subwoofer distance setting does not change the delay of the subwoofer output at all. So this appears to be a bug in the UMC-200 bass management.

I've tried to get more insight by using HDMI output in multi-channel mode from my laptop with the aid of ASIO4ALL, but I seem to be getting delay reference drift due to using two sound adapters (laptop HDMI for measurement system output, analog input of Tascam for measurement system input).


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## andy_c (Aug 8, 2006)

Well, it looks like my measurements in the post above were wrong. I went back and re-did the S/PDIF measurements and the sub delay is working as it should! I'm not sure what I was doing wrong before, but I cannot get it to misbehave now.

I fixed the delay reference drift I was having with HDMI mode, so now I have a whole lot of data for both S/PDIF and HDMI modes for many combinations of mains and sub distances. I'll do a comprehensive post soon with lots of plots and the MDAT files.

My conclusion is that they have fixed the bass management in going from the UMC-1 to the UMC-200.

I have not checked the EQ though.


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## dougc (Dec 19, 2009)

Good deal - I wish I had something helpful to add. There are so many different combinations and variables...


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## andy_c (Aug 8, 2006)

There were some reports of strange UMC-200 headphone out behavior, namely that the headphone out was being influenced by such things as speaker distance, speaker large/small, and other factors. So I tested the headphone out with S/PDIF in, stereo mode, using the left channel S/PDIF output of the Tascam US-144 MkII, and using the analog out of the right channel of the Tascam looped back to the right-channel analog input as the timing reference.

First, here's a rather strange-looking plot with front L/R speakers set to small, 100 Hz crossover at 24 dB/oct for high-pass and low-pass.










Next, I switched the front L/R speaker setting to large and re-ran the test. Results are shown below, and are more in line with expectations.










You can see that the frequency response at headphone out has changed. This suggests that the signal for the headphone out is being picked off downstream of processing intended for use with speakers. Exploring this further, I decided to look at the group delay at the headphone out with different speaker distance settings. First, here is the group delay with distance set to 32.8 feet (minimum delay).










Delay is about 3 msec at 200 Hz. Next, the distance was set to 0 ft. Results are below.










The headphone out delay has increased by 29 msec, corresponding to the speaker distance change. This confirms that the headphone signal is being picked off from a point downstream of where it should be, at a point after processing that should apply to speakers only.

Finally, here is a comparison plot showing the change in headphone out frequency response as the front L/R are changed from small to large.










These are the only bugs I've found so far, as other tests of the bass management (not shown) reveal the correct behavior.


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## Wolfgang (Feb 17, 2011)

I only just spotted this thread. Great to see someone taking the time to really investigate this. I've not long received my UMC-200. I was curious about the bass management (for the same reasons mentioned), but I see I don't have to check it now.  I think I read somewhere that the last firmware update of the UMC-1 also corrected the bass management issue?

I tried the 200 with my headphones, and there was a noticeable noise floor before playing anything. It seems to be great unit, but the headphone amp is not the finest aspect...


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## Sonnie (Apr 11, 2006)

That is awesome news... glad to know they finally figured it out. :T


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## jmilton7043 (Sep 21, 2011)

After having the UMC-1 for a few years, i am very pleased with the 200. It has better sound with EmoQ2 and is just much more stable than the 1 was. Glad to hear the bass mgt. is working well.


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## chashint (Jan 12, 2011)

To bad the headphone output is messed up.
That is a big problem.


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## jmilton7043 (Sep 21, 2011)

I believe that issue was address in a the latest SW update. I'll check with Lonnie Vaughn and confirm.


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## Wolfgang (Feb 17, 2011)

From what andy c has posted, that suggests it's more serious than firmware?

FWIW, my 200 has the latest firmware update and the noise floor is present. I've decided I'm going to buy an O2 amp for headphone listening.


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