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Discussion Starter · #1 ·
Hi there,

Looking for opinions, experience and anyone who might be able to verify my findings.

This morning, I did test of my Outlaw Audio 990's "Bypass Mode". First, I set my PC to output analog signals. I initially found this problem while listening to vinyl, so I don't want to throw digital into the mix. I used a Galaxy CM-140 SPL meter to take measurements. I had C-weighting enabled and "Slow" mode selected. I was in the "Medium" range (I think it's 50 to 100 dB).

First, crossover frequency did not seem to make a difference. Also, the sub selection of "LFE Only", "L+R+LFE", etc. did not seem to make a difference.

All measurements were taken using Bypass Mode.

So, to recap, I'm taking SPL measurement using pure tones sent using an analog signal from a PC. The 990 is in Bypass Mode for all measurements. The only thing I'm changing is the status of the mains from "Large" to "Small". I also scrolled through crossover settings and sub "configs" while measuring, and those seemed to have no effect.

Freq=76 Hz
Mains Lg = 73.1 dB
Mains Sm = 69.1 dB

Freq=50 Hz
Mains Lg = 63.4 dB
Mains Sm = 53.8 dB

I would expect there to be no change for the mains SPL readings based on Large or Small settings when using Bypass Mode.

I don't particularly care about the frequencies used, or the exact SPLs measured -- I'm mainly interested in the fact that there's a discrepancy between the mains small/large setting while in Bypass mode. (Actually, I think when I go home today, I will redo this test as higher frequencies as well). Is it digitizing the signal somewhere? Overall, it bothers me because I don't know what it's doing, it's not doing what's described in the manual/website, and if it's doing something weird here, what else is it doing that's weird?

Or am I missing something?
 

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Discussion Starter · #3 ·
Hey Wayne,

Yeah, that's what I was initially thinking, but I don't think it should do that. Also, crossover frequency doesn't make a difference. In the measasurements I noted above, it was at 40 Hz. I changed it to 200 Hz, and it was the same thing.

I'm talking with Steve at Outlaw and he said that with analog inputs in bypass mode the mains should get "full range" under all circumstances.

My latest question to them was: if, for whatever reason, there is some filtering going on in bypass mode, does that imply that there is and A/D/A process going on? It's my understanding that there should be no A/D/A in bypass mode...

It also worries me that some operations are just indeterminate in this device. If this is an across-the-board problem, it should have been caught in testing. What else is going on in there that we don't know about? Arrgh...
 

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Discussion Starter · #4 ·
Here are some sweeps I did this morning. Sub is unplugged, mains only. The only change between sweeps is to change front speaker size between large and small. I wasn't paying attention to graph axes when I saved this...

Looks it starts around 150 Hz or so. I did three sweeps for each setting to demonstrate repeatability.

mainslargesmallinbypassmode.jpg
 

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Maybe we should back the boat up:
I initially found this problem while listening to vinyl, so I don't want to throw digital into the mix.
Exactly what did you “find?” What was the audible manifestation?

Also, I overlooked something very obvious when I posted before: Your speakers. They’re going to make or break what you’re seeing. For instance, if they’re small bookshelf models they’re going to roll out the bass naturally.

The only change between sweeps is to change front speaker size between large and small.
Which is which? And what does it look like out of bypass, set to “Large?”

I wasn't paying attention to graph axes when I saved this...
Well, we really only have a “standard” for the REW / BFD Forum. Just make sure any others you post are the same, so we make sure we’re comparing Granny Smiths to Golden Delicious. :D

Regards,
Wayne
 

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Discussion Starter · #6 ·
Maybe we should back the boat up:
Exactly what did you “find?” What was the audible manifestation?
Hey Wayne,

The audible manifestation was just a lack of bass in the music. I think it was Steely Dan's Gaucho we were hearing at the time. I put it in bypass mode in the belief that it would skip all digital processing and bass management, as advertised by Outlaw. As soon as it went into bypass mode, it was clear that there was no LPF on the sub anymore. My IB relies upon the BM of my preamp, so without BM, it's just running full range to the sub. I also expected full range to the mains in this mode.

So, the sub's playing full range, and that doesn't sound too hot. So I just turn off my BFD so that the sub is totally gone. Listening further, I'm disappointed in the sound, specifically the bass. So I started flipping around in the OSD. As I switched from small to large (crossover point was set at 40 Hz, but should be irrelevant), the bass came back to life. And that's when I discovered what I think is this problem. The Outlaw site shows the BM matrix for analog and digital inputs, and for all cases when using analog inputs, bypass mode should send "full range" to the mains. Steve at Outlaw also told me that there should be no difference between small and large when using bypass mode for analog inputs (i.e., in either case, the signal should be full range).

Also, I overlooked something very obvious when I posted before: Your speakers. They’re going to make or break what you’re seeing. For instance, if they’re small bookshelf models they’re going to roll out the bass naturally.
Of course. I'm using the Vandersteen 3A Signature, a rather large floor-stander with an 8" and a 10" per speaker to handle the low end. IIRC, the 3 dB point is 30Hz

Which is which? And what does it look like out of bypass, set to “Large?”
Oh, sorry. I've been sort of haphazard in my descripton here... The "lower" measurement is with the mains set to "small". The higher amplitude measurement is with mains set to "large". I don't have any measurements for it in non-bypass mode and set to "large". I know it's hardly scientific, but in that case (e.g., using "stereo" mode or "upsample" mode), it sounds like the "large"/"bypass" case shown here (what I consider to be the good case). In other words, the "small"/"bypass" case is the one that's wrong, the deviant.

Well, we really only have a “standard” for the REW / BFD Forum. Just make sure any others you post are the same, so we make sure we’re comparing Granny Smiths to Golden Delicious. :D
Yeah, I figured it didn't matter too much for this. I just noticed it as I was re-reading my post, and wanted to say it before someone else did... :R
 

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As I switched from small to large (crossover point was set at 40 Hz, but should be irrelevant), the bass came back to life.
Well, based on your description of what you heard, and your graphs, it appears that either Steve is mistaken, or your 990 is malfunctioning. Not the news you wanted to hear, I’m sure. :(

Regards,
Wayne
 

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Discussion Starter · #8 ·
Yep, I'm really thinking that something is wrong with the 990. Steve's pretty much "the man" in the tech department, as far as I can tell. If he says it shouldn't do that, then it shouldn't do that. Plus, it just doesn't make any sense to roll off the mains in bypass mode. Bypass mode, in my book, is for straight analog, no processing, listening.

The good news is that the Outlaws will likely fix the problem. If it's across the board, with a firmware upgrade or, if it's just mine, with a new unit. There's a guy on the Outlaw board that's going to measure tonight and see what he finds. And we have out own Bob_99 here that has a 990 as well. Wonder if he saw this thread...
 
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Did Outlaw ever address your concerns ? This is a major bug that never should happen regardless of how bass management is implemented.
 

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Wonder if he saw this thread...
I have and will try and put something together to run some tests. I can't do it tonight but will get to it first chance that I get.

Bob
 

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Discussion Starter · #11 ·
Did Outlaw ever address your concerns ? This is a major bug that never should happen regardless of how bass management is implemented.
Unfortunately, they have not yet given me a fix. I have a couple other outstanding issues with them as well. Scott at Outlaw told me they are going to address all my issues "beyond my expectations." This was a couple weeks ago, and I haven't heard back since. Being a firmware engineer, I know that these things can take time, so I've giving them some slack. Still, I've been meaning to compile a concise and meaningful list that describes all my issues and questions, and then I will give Scott a call. I will say that they have been not directly answering my questions, specifically "if there is a HPF filter of some sort applied in bypass mode, is it being implemented in the digital domain. If so, why are you digitizing the analog bypass signal when you should not be?" I've just been too busy to get my act together enough to give him a meaningful call. I will certainly post here when I have more info.

Bob_99 said:
I have and will try and put something together to run some tests. I can't do it tonight but will get to it first chance that I get.
No problem, Bob. I know how we all get so busy! You won't need much of a test though -- just listen to full range speakers in bypass mode with an analog input. You'll hear it straight away. Since my original posts here and at the "Outlaw Saloon" (their forum), others have also heard the issue. Still, if you have time, please do post your observations or measurements.

BTW, I noted that Steve was the tech support guy at Outlaw. He's no longer with the company, so Scott is my main contact there at this point...

FWIW, here's my other thread that shows some measurements of my 990, and some problems therein.
 

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Otto,

I'm not sure if I did this correctly but I set up everything using the wiring scheme indicated for measuring the AVR. I used video 5 for the input and the right channel for the output. Crossover was set to 60 (also did a run at 100 which yielded pretty much the same results). First did stereo and then bypass. Here are the results:

Speaker set to large and sub set to none:
Black is stereo; olive is bypass


Speaker set to large and sub set to LFE:
Green is stereo; gold is bypass


Speaker set to large and sub set to L/R+Sub:
Aqua is stereo; dark blue is bypass


Speaker set to small and sub set to yes:
Purple is stereo; orange is bypass


This is my first time with REW so if anyone can point out mistakes, please do so. If this is not what you wanted, let me know what I need to do differently.

Thanks.

Bob
 

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Discussion Starter · #13 ·
Hi Bob,

I think you got it right. The last one is the one that I'm complaining about. The orange line should have no high pass filter applied.

That first one is weird to me as well. That's with the speaker set to large in stereo mode, so I would expect it to be flat to at least 20 Hz. Instead, there's a big dip at 70 Hz and then it get hotter as it goes lower. I haven't seen that myself, but I'm not sure I measured that path. I will check that again when I have time. I still need to get all my thoughts together and give Outlaw a call. I've lost a lot of enthusiasm for my system after hearing and measuring these differences...

Thanks, Bob!
 

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Hi Otto,

Yes, that first one is really strange but it is repeatable, even at a different crossover. I'm scratching my head over it myself. Also, I'm a bit unclear why you would expect the filter to be gone when the speaker is set to small. To my way of thinking, any time the sub is available, I would expect the filters to be engaged, bypass or not. Otherwise wouldn't you be sending the wrong type of signal to the sub?

:scratchhead::scratchhead::scratchhead:

I'm a bit dissappointed that Outlaw has not given you an answer by this time. They are usually excellent with support. Makes me wonder ...

Bob
 

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Discussion Starter · #15 ·
Hi Bob,

When using "bypass mode" with an analog input, both the main and sub signals should be full range. Here's the bass management matrix for analog intput (and for completeness, here's the digital BM matrix). The thing with analog processing is that I don't want my signal to be sampled into the digital domain. Say I've got my favorite turntable or an uber-expensive DAC -- I want that signal just to go straight through, with no digitization.

So although the mains may be set to "small", since all this BM stuff is applied in the digital domain, we can't have it when using analog inputs that we want to preserve in the analog domain. They're allowing you a means to do all your own bass management if you're into that kind of thing.

As to your #1 plot, I'm going to try to repeat that myself. It may be another bug...
 

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Otto,

Thank you for taking the time to explain it to me. Also, thanks for the great link on the matrix which I can't believe I missed. I look forward to your test results on 1. I was looking at my other tests and it looks like for the 100 Hz crossover, the null is exactly at 100 Hz. However for the 60 Hz crossover, it appears to be around 70 which blows my idea that it was related to the crossover.

Bob
 

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Discussion Starter · #17 ·
Hey Bob,

What firmware do you have? You can tell by turning off your 990 and pressing and holding the "Enter" button (the one in the middle of the Left/Right/Up/Down buttons) and then simultaneously pressing the "Input" button. This has to be done from the front panel. Be sure that you don't hit "Enter" and "Menu" at the same time, as that will do a "System Reset," which will force you to re-enter all your setup information.

The latest firmware version reads something like "Ver 3.11 04".

Just curious, because I know the original firmware version had some bass management issues, though I admit that I don't know what they are.
 

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Otto,

Didn't see your message until this morning so I can't check until tonight. I did install the patch (3.11) and thought that it installed correctly but I'll still check to be sure. Have you had any chance to try the settings of speakers:large and sub:none? I can't imagine why it dips like that.

Bob
 

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Discussion Starter · #19 ·
Almost but ran out of time last night because I accidentally did the "System Reset" instead of the "Firmware Reset" thing. Tonight's looking good for some free time, and it should only take a minute. I was going to start bugging Outlaw again about the problems, but if this is another one, I want it on the list as well.
 

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Almost but ran out of time last night because I accidentally did the "System Reset" instead of the "Firmware Reset" thing.
Oops!

Tonight's looking good for some free time,
My wife is working tonight so it's a great night for me. I'll definitely get the firmware version and if you can think of any other tests that we can do, just let me know.

Bob
 
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