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I'm done with the SMS-1, it limits the output of my Submersives - Page 2

post #31 of 58
Quote:
Originally Posted by Stereodude View Post

Quote:
Originally Posted by BeeMan458 View Post

"The 0 dB reference level represents an average 85 dB SPL and a maximum 105 dB SPL. The LFE (Low Frequency Effects) channel used by AC3 (Dolby Digital) and DTS is +10 dB higher. This means that the maximum output for bass peaks is 115 dB SPL. The purpose of the +10 dB gain for the LFE channel is to increase the dynamic range of bass events such as explosions, crashes, punches, and rumbles. This means when the volume is set to 0 dB that the subwoofer could be asked to produce an output of 115 dB SPL".
Yes, but considering bass management and 7 channels at 105dB and a subwoofer at 115dB you get 117.3dB according to the dB calculator on this page.


Wrong calculator. "Summing up to ten non-coherent or uncorrelated noise sources"

All bass sent to the subwoofer is coherent for all practical purposes.

Read the notes for that calculator.

"For beginners: non-coherent means the signals of the overdubbed channels are irrelative like a violin and a trumpet,
that means having no correlative relationship. Sometimes we say uncorrelated when we mean non-coherent."
post #32 of 58
Quote:
Originally Posted by BeeMan458 View Post

Not arguing on any level. In response, I'm just posting the facts as I understand them. Room gain and bass management? That's whole "nother" story. I'm just posting in regard to what the THX reference standard is and everything else is outside my pay grade.
THX calls for an average of 85dB with headroom and an additional +10dB bump for the LFE channel and headroom. My comments are intended to address the simple of it all as opposed to trying to address room gain, bass management and the synergism of seven highly efficient (+95dB/1W/1M sensitivity) speakers banging away in unison while coupled to a pair of bad boy fifteen or eighteen inch subwoofers with over 2,400 peak watts behind the subwoofers.
Yes, but THX assumes you have 5 or 7 speakers capable of 105dB covering the entire frequency range. People who run their speakers as small require the subwoofer to pick up the redirected bass. That means the subwoofer must utimately be capable of something greater than 115dB.
post #33 of 58
Quote:
Originally Posted by J_Palmer_Cass View Post

Wrong calculator. "Summing up to ten non-coherent or uncorrelated noise sources"
All bass sent to the subwoofer is coherent for all practical purposes.
Read the notes for that calculator.
"For beginners: non-coherent means the signals of the overdubbed channels are irrelative like a violin and a trumpet,
that means having no correlative relationship. Sometimes we say uncorrelated when we mean non-coherent."
If we were adding up 40Hz sine waves from every channel I'd agree that they're coherent, but how is a 40Hz and 65Hz sine wave coherent?

Further, 7 coherent channels at 105dB + a coherent sub at 115dB still doesn't equal 121dB. It's 125.14dB
5 coherent channels 105dB + a coherent sub at 115dB also doesn't equal 121dB. It's 123.236dB.
Edited by Stereodude - 1/3/13 at 11:20am
post #34 of 58
Quote:
Originally Posted by Stereodude View Post

Quote:
Originally Posted by sputter1 View Post

That's how I understand it.
Except that's not how the math works. 105dB*7 + 115dB = 117.3dB, not 121dB.



You only need three channels at 105 dB and one channel at 115 dB to get 121 dB via bass management (AKA electrical addition).


http://www.sengpielaudio.com/calculator-coherentsources.htm
post #35 of 58
Quote:
Originally Posted by Stereodude View Post

Except that's not how the math works. 105dB*7 + 115dB = 117.3dB, not 121dB.

The above makes the assumption that even the surrounds are cranking out 105dB. I realize this is all in the hypothetical but that's some crescendo.
post #36 of 58
Quote:
Originally Posted by Stereodude View Post

Quote:
Originally Posted by J_Palmer_Cass View Post

Wrong calculator. "Summing up to ten non-coherent or uncorrelated noise sources"
All bass sent to the subwoofer is coherent for all practical purposes.
Read the notes for that calculator.
"For beginners: non-coherent means the signals of the overdubbed channels are irrelative like a violin and a trumpet,
that means having no correlative relationship. Sometimes we say uncorrelated when we mean non-coherent."
If we were adding up 40Hz sine waves from every channel I'd agree that they're coherent, but how is a 40Hz and 65Hz sine wave coherent?

Further, 7 coherent channels at 105dB + a coherent sub at 115dB still doesn't equal 121dB. It's 125.14dB
5 coherent channels 105dB + a coherent sub at 115dB also doesn't equal 121dB. It's 123.236dB.



Coherent means in phase.

Peaks of 40 Hz and 65 Hz sine waves will be 100% in phase at certain times even thought they are different frequencies.
post #37 of 58
Quote:
Originally Posted by J_Palmer_Cass View Post

Coherent means in phase.
Peaks of 40 Hz and 65 Hz sine waves will be 100% in phase at certain times even thought they are different frequencies.
So, that only means the calculated "coherent" SPL is correct what 1/25 of the time? The other 24/25th of the time the non-coherent SPL is correct.
post #38 of 58
Quote:
Originally Posted by Stereodude View Post

Quote:
Originally Posted by J_Palmer_Cass View Post

Coherent means in phase.
Peaks of 40 Hz and 65 Hz sine waves will be 100% in phase at certain times even thought they are different frequencies.
So, that only means the calculated "coherent" SPL is correct what 1/25 of the time? The other 24/25th of the time the non-coherent SPL is correct.



That means if you use a signal generator with a simultaneous -5 dB FS 40 Hz sine wave and a - 5 dB FS 65 Hz sine wave, you will clip on a digital basis due to coherent signal addition of 6 dB.
Edited by J_Palmer_Cass - 1/3/13 at 11:51am
post #39 of 58
Quote:
Originally Posted by Archaea View Post

do you play your equipment 10dB above reference like carp? tongue.gif
the problem seemed legit, but at levels far far far above normal.

With 20 subs I would say I could barely manage those levels biggrin.gif Pretty much he room felt like it was going to crumble, both with the SMS-1 in and out of the system wink.gif
post #40 of 58
Man I really wish I knew what y'all were talking about here. redface.gif
Makes me wonder how much more potential my system could be if I took the time to learn all this verbage.
post #41 of 58
Quote:
Originally Posted by carp View Post

Hey Craig, the preset I used was #6 which doesn't apply any eq, that way I could be sure that I was measuring the same frequency response as when I took the SMS-1 out of the chain.
Now, the other presets had some cuts and boosts (mostly cuts, very little boosting) but I wasn't using any of them for this comparison. I double checked to make sure no HPF was on and absolutely no eq applied.
Did you try raising the Volume past 15? It could be that, in your particular unit, Unity Gain is higher than 15. You might want to pose your questions/issues in the Official Velodyne Support Thread. http://www.avsforum.com/t/304306/offical-velodyne-support-thread There are some factory support guys who post there. They may be able to shed some light on the issue.

Quote:
Originally Posted by carp View Post

Craig, are you still using your sms-1? When you get a chance can you check it sometime make sure it's not happening to you?
I no longer have my SMS-1. I took it out when I moved to Submersives and Audyssey XT32. It was no longer necessary. I probably never saw the limits of the SMS-1 because, at the time, I had a pair of JL Audio F112's. They were the limiting factor in that system, not the SMS-1.

Craig
post #42 of 58
Thread Starter 
Quote:
Originally Posted by craig john View Post

Did you try raising the Volume past 15? It could be that, in your particular unit, Unity Gain is higher than 15. You might want to pose your questions/issues in the Official Velodyne Support Thread. http://www.avsforum.com/t/304306/offical-velodyne-support-thread There are some factory support guys who post there. They may be able to shed some light on the issue.
I no longer have my SMS-1. I took it out when I moved to Submersives and Audyssey XT32. It was no longer necessary. I probably never saw the limits of the SMS-1 because, at the time, I had a pair of JL Audio F112's. They were the limiting factor in that system, not the SMS-1.
Craig

No, I didn't try any higher than 15, but I'll do some more experimenting. I'll try Velodyne support too. If there is an issue I can figure out that would be great, I do like using it.

I do know that when I was calibrating the sub with the speakers the difference between using the sms-1 and not using it was only around 1 db with the test tones.
post #43 of 58
Quote:
Originally Posted by Stereodude View Post

Quote:
Originally Posted by carp View Post

Dammit guys I said this already but I'll try again, MY RECEIVER IS AT -10 WHEN CALIBRATED, so that means it is at 0 when the sub is 10 dbs hot.
My first post meant I was running the subs 10 dbs hot, NOT that the sub out volume was at +10 on the receiver.
Ok, that sounded angry - sorry!! eek.gifsmile.gif
That doesn't mean you're not clipping your LFE signal somewhere in the chain. For example, I can clip the SW output of my Pioneer Elite SC-05 with the SW level trim at 0 and the master volume at 0. You're probably clipping the input of the SMS-1 (or it's clipping its output), but it can start at the receiver's output.

I'd like to hear more about you clipping the SW ouput, call me curious. tongue.gif
post #44 of 58
Quote:
Originally Posted by sputter1 View Post

I'd like to hear more about you clipping the SW ouput, call me curious. tongue.gif
Well, curious... I found all of my receivers will clip the SW output if you turn up the volume enough and have a sufficiently "hot" signal. I tested my Pioneer Elite SC-05, Onkyo TX-NR809, and Pioneer Elite VSX-84TXSi. Here's the output of a -0.01dBFS 40Hz signal DTS encoded into all 6 channels. The SC-05's master volume is at 0dB and the SW trim is at 0dB.

post #45 of 58
Don't bother fixing the SMS....Just sell it to me biggrin.gif:D:D
post #46 of 58
Thread Starter 
Quote:
Originally Posted by pokekevin View Post

Don't bother fixing the SMS....Just sell it to me biggrin.gif:D:D

I was thinking about selling it. However, I dragged my old HSU MBM-12 out of storage today because I was going to sell it and wanted to make sure it still works fine. I plopped it down behind my LP fired up some music... and really dug it. So much so that I called the guy and told him I changed my mind I'm going to keep the mbm. Sh*t move on my part, he lives a couple hours out of town and was already on his way - I apologized profusely and he was very cool and understanding about it, but I feel bad about it.

In the past I could never use the MBM right behind my LP because of fear of my kids messing with it, but I have them trained very well now not to touch my toys.

So, I'm thinking I could use the sms-1 on the MBM and not with the Submersive so I can have independent volume control since my receiver has dual sub outs, but it's like an internal y cable, no independent volume.
post #47 of 58
Quote:
Originally Posted by Stereodude View Post

Quote:
Originally Posted by sputter1 View Post

I'd like to hear more about you clipping the SW ouput, call me curious. tongue.gif
Well, curious... I found all of my receivers will clip the SW output if you turn up the volume enough and have a sufficiently "hot" signal. I tested my Pioneer Elite SC-05, Onkyo TX-NR809, and Pioneer Elite VSX-84TXSi. Here's the output of a -0.01dBFS 40Hz signal DTS encoded into all 6 channels. The SC-05's master volume is at 0dB and the SW trim is at 0dB.



Can you stop the clipping by lowering the master volume to any specific level while leaving the SW trim @ 0 dB?

Can you stop the clipping by lowering the subwoofer output trim to any specific trim level while leaving the MVC @ 0 dB?
post #48 of 58
Quote:
Originally Posted by carp View Post

I was thinking about selling it. However, I dragged my old HSU MBM-12 out of storage today because I was going to sell it and wanted to make sure it still works fine. I plopped it down behind my LP fired up some music... and really dug it. So much so that I called the guy and told him I changed my mind I'm going to keep the mbm. Sh*t move on my part, he lives a couple hours out of town and was already on his way - I apologized profusely and he was very cool and understanding about it, but I feel bad about it.
In the past I could never use the MBM right behind my LP because of fear of my kids messing with it, but I have them trained very well now not to touch my toys.
So, I'm thinking I could use the sms-1 on the MBM and not with the Submersive so I can have independent volume control since my receiver has dual sub outs, but it's like an internal y cable, no independent volume.

Haha does the mbm really add to the experience?
post #49 of 58
Quote:
Originally Posted by J_Palmer_Cass View Post

Can you stop the clipping by lowering the master volume to any specific level while leaving the SW trim @ 0 dB?
Can you stop the clipping by lowering the subwoofer output trim to any specific trim level while leaving the MVC @ 0 dB?
On the SC-05, yes to both. On the VSX-84TXSi, no not with this particular worst case test tone.

I'm not sure on the Onkyo. I didn't test it as closely. I only checked it for maximum output before clipping with a different test tone (-0.01dBFS 40Hz sine wave DTS encoded in the LFE channel only).
post #50 of 58
Quote:
Originally Posted by Stereodude View Post

Quote:
Originally Posted by sputter1 View Post

I'd like to hear more about you clipping the SW ouput, call me curious. tongue.gif
Well, curious... I found all of my receivers will clip the SW output if you turn up the volume enough and have a sufficiently "hot" signal. I tested my Pioneer Elite SC-05, Onkyo TX-NR809, and Pioneer Elite VSX-84TXSi. Here's the output of a -0.01dBFS 40Hz signal DTS encoded into all 6 channels. The SC-05's master volume is at 0dB and the SW trim is at 0dB.



Hmmm, you would be badly clipping the input of the SMS-1 with the use of those AVR subwoofer output jack voltage readings. Around 9 V RMS maximum readings if your chart is calibrated.

According to the thread below, the SMS-1 can only take an input of around 400 mV RMS when clipping starts.

http://www.hometheatershack.com/forums/electronic-processing-equalization-devices/6346-behringer-fbq2496-velodyne-sms-1-distortion.html#axzz2H0snJSms


"So for those owning the SMS-1, I would definitely set the subwoofer output on the receiver as low as it goes. Typically the subwoofer output can easily give a couple volts, and as you can see, it doesn't need much more than 0.4 volts to clip the input stage of the SMS-1."
post #51 of 58
Quote:
Originally Posted by J_Palmer_Cass View Post

Quote:
Originally Posted by Stereodude View Post

Quote:
Originally Posted by sputter1 View Post

I'd like to hear more about you clipping the SW ouput, call me curious. tongue.gif
Well, curious... I found all of my receivers will clip the SW output if you turn up the volume enough and have a sufficiently "hot" signal. I tested my Pioneer Elite SC-05, Onkyo TX-NR809, and Pioneer Elite VSX-84TXSi. Here's the output of a -0.01dBFS 40Hz signal DTS encoded into all 6 channels. The SC-05's master volume is at 0dB and the SW trim is at 0dB.



Hmmm, you would be badly clipping the input of the SMS-1 with the use of those AVR subwoofer output jack voltage readings. Around 9 V RMS maximum readings if your chart is calibrated.

According to the thread below, the SMS-1 can only take an input of around 400 mV RMS when clipping starts.

http://www.hometheatershack.com/forums/electronic-processing-equalization-devices/6346-behringer-fbq2496-velodyne-sms-1-distortion.html#axzz2H0snJSms


"So for those owning the SMS-1, I would definitely set the subwoofer output on the receiver as low as it goes. Typically the subwoofer output can easily give a couple volts, and as you can see, it doesn't need much more than 0.4 volts to clip the input stage of the SMS-1."

I'm finding this interesting even though I don't have the knowledge to read Stereodude's graph. If i'm following correctly, the suggestion being made is to reduce the sub trim level on the avr and bump the lvl on the SMS-1? I think some or all AVRs go +10/-10 on the trim level so bringing it down to -10 and raising it on the SMS-1 will solve the clipping?
post #52 of 58
Quote:
Originally Posted by sputter1 View Post

I'm finding this interesting even though I don't have the knowledge to read Stereodude's graph.

In the simple, equipment likes dome tops not flat tops and when one gets the hair on their dome cut, they get clipped.

Square wave, vs modified square wave vs full sine wave.
post #53 of 58
Quote:
Originally Posted by sputter1 View Post

I'm finding this interesting even though I don't have the knowledge to read Stereodude's graph. If i'm following correctly, the suggestion being made is to reduce the sub trim level on the avr and bump the lvl on the SMS-1? I think some or all AVRs go +10/-10 on the trim level so bringing it down to -10 and raising it on the SMS-1 will solve the clipping?
Well, it depends on how loudly you listen. If you listen at reference (0dB) even a setting of -10 on the SW channel trim will only reduce the voltage of a worst case amplitude signal like this to 4.48Vrms, which is still way beyond what the SMS-1 can reportedly handle.
post #54 of 58
Quote:
Originally Posted by Stereodude View Post

Quote:
Originally Posted by sputter1 View Post

I'm finding this interesting even though I don't have the knowledge to read Stereodude's graph. If i'm following correctly, the suggestion being made is to reduce the sub trim level on the avr and bump the lvl on the SMS-1? I think some or all AVRs go +10/-10 on the trim level so bringing it down to -10 and raising it on the SMS-1 will solve the clipping?
Well, it depends on how loudly you listen. If you listen at reference (0dB) even a setting of -10 on the SW channel trim will only reduce the voltage of a worst case amplitude signal like this to 4.48Vrms, which is still way beyond what the SMS-1 can reportedly handle.

Calibrated at 75db, the highest I would ever run the MV at would be -5
post #55 of 58
Quote:
Originally Posted by J_Palmer_Cass View Post

Hmmm, you would be badly clipping the input of the SMS-1 with the use of those AVR subwoofer output jack voltage readings. Around 9 V RMS maximum readings if your chart is calibrated.

According to the thread below, the SMS-1 can only take an input of around 400 mV RMS when clipping starts.
http://www.hometheatershack.com/forums/electronic-processing-equalization-devices/6346-behringer-fbq2496-velodyne-sms-1-distortion.html#axzz2H0snJSms

"So for those owning the SMS-1, I would definitely set the subwoofer output on the receiver as low as it goes. Typically the subwoofer output can easily give a couple volts, and as you can see, it doesn't need much more than 0.4 volts to clip the input stage of the SMS-1."
The scope plot is accurate. The SC-05 can output a clean peak to peak voltage of ~22.6V, which ~8Vrms with a sine wave. My 84TXSi has the same output capability. My Onkyo NR809 is pretty much the same also.

FWIW, the RMS voltage of that signal is listed on the plot. Keep in mind that RMS voltage is really not the right thing to discuss when talking about clipping since the RMS voltage changes depending on the shape of the waveform (it's effectively related to area under the curve). The measured RMS voltage keeps increase even as the waveform becomes more and more clipped. On the other hand, peak to peak voltage is always peak to peak voltage regardless of the waveform's shape and it doesn't increase as the waveform gets more and more clipped.

At least the balanced 2x4 MiniDSP clips at ~4.6Vrms [with sine waves] / 13.5Vpp and IMHO it should accept and output even high amplitude signals since they clearly can exist in the SW output. If the SMS-1 really clips at 400mVrms it's completely and utterly useless for SW equalization in any serious HT system and highly questionable for a 2.1 music setup.
post #56 of 58
Quote:
Originally Posted by sputter1 View Post

Calibrated at 75db, the highest I would ever run the MV at would be -5
Of course it's dependent on what receiver you have, but in the case of the Pioneer Elite SC-05, -5dB on the MV with -10dB on the SW level trim (as low as it goes) can still output a SW voltage of ~2.5Vrms (sine waves). The Onkyo 809 would fare a little better since the SW trim can be reduced to -12dB and its SW output isn't quite as "hot". It would be somewhere around 1.4Vrms (sine waves) This assumes you don't use some of the other LFE reduction options in the receiver.
post #57 of 58
Thanks Carp, interesting thread. I am almost positive I tested for this when I got my SMS years ago and was hitting the same max with or without the SMS in the chain, but I am curious to retest this now. I am also curious to test it with my multiple sub configuration since the first time I tested was with a single which should not matter in theory I would not think, but you never know.

Question...........I have one Y-cable coming out of my sub out on my pre-pro now, one end goes to my SMS and the other to my BK amp. Can I just unplug the BK from one end of this Y-cable and then use 2 more Y-cables attached to each end of the Y coming out of the sub out so I have 4 sub outputs? Any issues doing this? I would like to test this now after reading this thread to confirm (I hope!) my original findings and to see if going from 1 to 4 subs has caused this to change for any reason.

Thx
post #58 of 58
Hi, would like to get some FB here are my settings ?
Everything is set to 80hz and small, all speaker are at 75db, sub at 85db

I do find lower sub level using with my Rotel 1570
I also noticed higher sub vol without sms-1
I know the volume on sms is just a utility gain but I never notice any changes to the sub volume...





Edited by motogp34 - 10/15/13 at 10:11pm
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