Cannot level match Subs to Mains

Frodo

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Hello Members,

Hopefully someone will be able to help me with this issue.

I have REW installed on a Dell XP13, with a UMIK-1 plugged into the headphone jack of the laptop, and the right/left RCA connectors into my DAC. I use the balanced out connections to connect to my amp and both subs via a pair of Whirlwind Split 6 (dual mono subs with both L/R channels). I've also tried using the balanced out from the DAC directly to the subs and it doesn't make any difference.

Using the Check Level feature, I need to basically set the volume on my farthest sub from MLP to max, as well as my DAC to get to about 76dB. I can dial back the subs volume by about 4 clicks to get 76dB on the closer sub.

Subs are Rythmik EP15. One is 13' in front of me, positioned along the left wall, about 4' from the front wall (sub is facing directly at the right wall). The other sub is along the right wall (facing directly at the left wall), behind the couch of the MLP (about 7'). Room width is 13' by 40' long.

My mains are 8' from MLP in an equilateral triangle set up. Sensitivity is 91db/4ohms.

When I measure the mains, I only need to set the DAC volume at -22 to get 76dB, where the subs need the DAC to be -2dB.

If I leave the DAC at -22dB, it means I'm not really getting much output from the subs at all.

Does anyone have any suggestion how I could get the subs and mains to the same level?

I've tried increasing the volume setting on the microphone in Windows 10 from 53 to 100, but it doesn't make any difference.

I've also done nearfield measurements with one of the subs in the middle of the room, and the mic is about 1/2" from the center of the sub. I have no problem getting to 100dB.

Please note, this is for an audio system only, I don't have anything connected to a DSP to allow EQ'ing.

Thanks.
 

ddude003

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It might be helpful to know the make and model of the DAC and Amp... And are you running a Preamp?
I am guessing there is a gain mismatch between output from the Amp to the Left and Right mains and what I think you are saying from the DAC to your Subs... Do your Subs have a volume/gain adjustment on it? I couldn't find a "Rythmik EP15"... Is it just a E15?

I am also confused about running the mic from the headphone jack... Wouldn't that be mic as input and headphones as output? Maybe its a headset with a mic? And running the DAC from L/R RCA connectors seems odd... Is there a reason to not be using USB? Maybe a sketch of all these connections would help...

Next guess is the Whirlwind Split 6... As included from the manual here for educational purposes:
"* Line level outputs can usually be split 6 times without noticeable loss of signal quality. The actual number of splits that can be accomplished depends on the level of the source signal and the impedances of the source and destinations in a particular application...".
 
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Frodo

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The UMIK-1 is plugged into the USB port as the microphone.
The RCA cable is plugged into the 1/8" TRS as speaker (on laptop), and RCA input on DAC (the cable has both L/R channels because the TRS jack is stereo).
The Split 6 works fine, that's why I mentioned I tried measuring the subs directly connected to balanced output on DAC (volume levels are no different than when using the Split 6). Meaning, I disconnected the amps when doing the test because there's only 1 set of balanced outputs from the DAC.
I use the DAC as the preamp. MSB Platinum III - 7.5 V RMS (20Vpp) on the Balanced Outputs
Subs are E15HP2.
 

ddude003

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Cifte 12AU7 NOS & Genalex Gold Lion Tubes in Pre
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Netgear Nighthawk S8000 Streaming Switch, Lumin U1 Mini Streamer Transport
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QoBuz Studio Premier, Amazon Prime & Netflix
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ThrowRug, SaddleBlankets, WideBand & Bass Traps...
Lets see if I got this straight... You have a MSB DAC with 1 pair of Balanced Outs connected to a Split 6 via its Balanced Inputs... The other side of the Split 6 there is a pair of Balanced Outputs going to an Amps (what kind of amp?) Balanced Inputs, another pair of Split 6 Balanced Outputs to one Rythmik E15HP2s Balanced Inputs and another pair of Split 6 Balanced Outputs to the others Rythmik E15HP2's Balanced Inputs...

Things to think about... The MSB Platinum III, as a Preamp, is driving 3 Amps via 3 pair of Parallel Balanced Outputs... I don't know if the MBS can drive that load... What is the Gain Structure difference between the Amp used for the Left and Right speakers and the Amps in each Sub? Is there a volume control on the subs you can try turning up? Is there a Limiter switch you can turn off on the subs?
 

Frodo

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Right, 1 split 6 for left side, another split 6 for right side to amps and both subs.
As mentioned, if I don't use the split 6's and output from the DAC directly to either sub, measurements and results are pretty much the same as using the split 6's. DAC and Subs both need near full volume. Speaker volume on PC is always 100%.
I tried bypassing the volume control on the DAC (setting to 0 dB), and that worked out to be the same issue.
Also, I use a different PC to listen to music. With this PC (music server), I use HQPlayer and the input on the DAC is done via AES/EBU (digital). The volume on the subs can only be turned up about 5-6 clicks from minimum or else it's way too much bass.
I have no problem using a sine wave file from this PC to level match the subs and mains.
However, I cannot use REW to measure anything from this system. This system uses ethernet out to a digital converter that outputs the signal into AES (into the DAC).
 

ddude003

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Additional Amp
Yamaha RX-A850 Pro (the other 5 channels lol)
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MacBook Pro, Custom i7 7700k De-lid 2xAsus1080ti GFX Audirvana Studio, Hang Loose Convolver, Pulsar Massive & 8200, LiquidSonics, SoX
DAC
Chord Electronics Ltd. Qutest
Universal / Blu-ray / CD Player
Sony UBP-X700 /M Ultra HD 4K HDR & PS5
Front Speakers
Martin Logan ElectroMotion ESL
Center Channel Speaker
Martin Logan Motion C2
Surround Speakers
Martin Logan Motion 4
Surround Back Speakers
Martin Logan Motion 4 (yes, another set of these)
Subwoofers
Martin Logan Dynamo 700
Other Speakers or Equipment
Cifte 12AU7 NOS & Genalex Gold Lion Tubes in Pre
Video Display Device
Samsung The Premiere LSP7T UST Laser Projector
Screen
Elite Screens Aeon CLR3 0.8 Gain 103-inch
Remote Control
PrimaLuna, Lumin iApp, Samsung & Yamaha
Streaming Equipment
Netgear Nighthawk S8000 Streaming Switch, Lumin U1 Mini Streamer Transport
Streaming Subscriptions
QoBuz Studio Premier, Amazon Prime & Netflix
Other Equipment
ThrowRug, SaddleBlankets, WideBand & Bass Traps...
There is a way to do a external / offline sweep with REW... So you can play the sweep on one system and measure with just REW from a laptop with a mic... The two components don't need to be connected... I only did this once a long time ago... So... Maybe someone else jump in and lend a hand...
 

Frodo

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Thanks guys, but I don't have another system I can use for measuring. My other music server doesn't have any hardware for speakers out. It's just a mini-ITX motherboard. As mentioned before, I use ethernet for audio to an external digital converter (AoIP). I would have loaded REW on that system as well if it had the necessary connections (before creating this thread).
 

JStewart

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Nope, I have it set to Normal Mode.

Should it not be on dual if you are running 1 xlr to each sub? I think normal is for running both a right and left channel connection to each sub. Or is that what you are doing?
 

JStewart

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Also, I use a different PC to listen to music. With this PC (music server), I use HQPlayer and the input on the DAC is done via AES/EBU (digital). The volume on the subs can only be turned up about 5-6 clicks from minimum or else it's way too much bass.

Sorry, I missed this. So you're saying there's plenty of bass when using you regular signal chain, but not with REW on another laptop, correct?

There is a way to do a external / offline sweep with REW... So you can play the sweep on one system and measure with just REW from a laptop with a mic..

Thanks guys, but I don't have another system I can use for measuring. My other music server doesn't have any hardware for speakers out. It's just a mini-ITX motherboard. As mentioned before, I use ethernet for audio to an external digital converter (AoIP). I would have loaded REW on that system as well if it had the necessary connections (before creating this thread).

I think the idea here is use the laptop with REW to generate a file that you play with your normal signal chain, then just use the laptop with REW and the usb mic to measure with. I'm being a little slow this evening, so perhaps I don't understand, again! Apologies in advance if that's the case.

What happens when you run a sine sweep for the sub (or use RTA with Pink PN signal) with the laptop that has REW and usb mic, even though the volume is low? Does the sub response appear normal?
 

ddude003

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Preamp, Processor or Receiver
PrimaLuna Dialogue Premium TubePre (2 channel+sub)
Main Amp
McIntosh MC152 SS Amp (2 channel)
Additional Amp
Yamaha RX-A850 Pro (the other 5 channels lol)
Computer Audio
MacBook Pro, Custom i7 7700k De-lid 2xAsus1080ti GFX Audirvana Studio, Hang Loose Convolver, Pulsar Massive & 8200, LiquidSonics, SoX
DAC
Chord Electronics Ltd. Qutest
Universal / Blu-ray / CD Player
Sony UBP-X700 /M Ultra HD 4K HDR & PS5
Front Speakers
Martin Logan ElectroMotion ESL
Center Channel Speaker
Martin Logan Motion C2
Surround Speakers
Martin Logan Motion 4
Surround Back Speakers
Martin Logan Motion 4 (yes, another set of these)
Subwoofers
Martin Logan Dynamo 700
Other Speakers or Equipment
Cifte 12AU7 NOS & Genalex Gold Lion Tubes in Pre
Video Display Device
Samsung The Premiere LSP7T UST Laser Projector
Screen
Elite Screens Aeon CLR3 0.8 Gain 103-inch
Remote Control
PrimaLuna, Lumin iApp, Samsung & Yamaha
Streaming Equipment
Netgear Nighthawk S8000 Streaming Switch, Lumin U1 Mini Streamer Transport
Streaming Subscriptions
QoBuz Studio Premier, Amazon Prime & Netflix
Other Equipment
ThrowRug, SaddleBlankets, WideBand & Bass Traps...
So, yea... I'm a little slow tonight too... Do you have one or two of those Whirlwind Split 6 devices in this system??? And what Amp(s) for the L & R speakers... Oh, and the L & R speakers themselves... What are they? Sorry if I missed this information up-thread...

You do know that you don't need a full physical loop to measure your system with REW... Just the lappy and a mic can do...
 

Frodo

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Yes, plenty of bass when using the music server and playing sine wave loops out of HQPlayer. Far more than enough.
If I'm level matching the mains to both subs (from music server, using SPL meter), I normally have the DAC at -22, for the mains (80dB), and the subs are turned up about 6 clicks on one and 7 clicks on the other from the minimum volume setting (different distances from MLP). With both speakers (Wilson Sasha's), and both subs running, and because of some gain with all four, I need to dial back the subs 1 or 2 clicks on both to get 80dB on my SPL meter. I sometimes dial the subs back even another click because the bass is a bit too loud. Amps are Pass Labs XA160.5.
Yes, I have two Whirlwind Split 6 XLR splitters (one for left side and other for the right side).
I'm only interested in measuring from 15-200Hz frequency range, so that's all I need.
How can I create the REW sweep tones for that range and save it to a .wav file? I could copy that file to the music server, play it in a loop there, and only have the mic plugged into the laptop to take the measurements.
 
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JStewart

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How can I create the REW sweep tones for that range and save it to a .wav file? I could copy that file to the music server, play it in a loop there, and only have the mic plugged into the laptop to take the measurements.

John put a link in post 7 for this.
You will use Tools=>Generator (or the generator icon) to open the signal generator.
Select the signal type and attributes you are looking for.
Press save to file.

2021-01-05 (1).png
 

Frodo

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OK, I've read through John's post again and it seems simple enough.
I won't be able to do this until later, but I do have a question.
To facilitate the 'Check Levels', is it just a matter of setting the desired dB SPL on the other system using a SPL meter before running the measurements? Thanks.
 

Frodo

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OK, so I ran the test and it seems to work, but I have to use my main speakers because there's a signal at the beginning and and another signal at the end to let REW know when to start and stop the measurement. The issue with this, is to compare apples to apples I would like to test the subs on their own using the same method. Problem is the subs are set to 40Hz and the Begin/End signals are not audible from just the subs - only when the main speakers are part of the test as well.
 

JStewart

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OK, so I ran the test and it seems to work, but I have to use my main speakers because there's a signal at the beginning and and another signal at the end to let REW know when to start and stop the measurement. The issue with this, is to compare apples to apples I would like to test the subs on their own using the same method. Problem is the subs are set to 40Hz and the Begin/End signals are not audible from just the subs - only when the main speakers are part of the test as well.

Instead of a sine sweep you could use Periodic Pink Noise.

38267


Change the repetitions field to increase the length of the recording. I'd suggest 90 sec to 2 min.

On playblack record with REWs RTA (real time analyzer.

38268



Above is a recording of a sub using the RTA and Periodic Pink Noise. The settings box is opened to view the settings. In the background is the measurement after saving the RTA capture. The RTA recording of the signal was done with "spatial averaging" a.k.a. moving mic method or MMM. It's also smoothed which helps visualize the level as sub responses can be quite erratic due to room effects.

This video shows MMM technique.
 

Frodo

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JStewart - thanks for the suggestion. I'll have a look at that later on.
Today I figured out a way to use my music server with Windows 10 using the WDM audio device driver.
I was able to install REW on my music server, level match all speakers, and take measurements.
 

JStewart

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JStewart - thanks for the suggestion. I'll have a look at that later on.
Today I figured out a way to use my music server with Windows 10 using the WDM audio device driver.
I was able to install REW on my music server, level match all speakers, and take measurements.

Outstanding.Good to hear.
 

dotnet

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Instead of a sine sweep you could use Periodic Pink Noise.
[...]

This video shows MMM technique.

Very interesting, thanks for linking that video. I had no idea you could use RTA for taking measurements, I always just saw it as a real-time only tool. For room EQ I’ve always used lots of sweeps from various mic positions around the listening spot, and that always took a long time. The MMM technique seems much more straight-forward, I’m definitely giving that a try.

A couple of questions:
- Should they have use pink periodic noise instead of plain pink noise, or does it not matter?
- I suppose the RTA based measurement is for EQ purposes only, not anything timing related?
- Do the RTA settings matter much (16k length, Hanning, 1/24th from memory in the video?), what should suitable settings be?
- This should still be done for each speaker individually, correct?
 

JStewart

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- Should they have use pink periodic noise instead of plain pink noise, or does it not matter?

Periodic has been recommended by @John Mulcahy REW's author for this purpose. I have a basic understanding that periodic has more equal energy vs pink which is more random.

- I suppose the RTA based measurement is for EQ purposes only, not anything timing related?

Yes. There is no timing info available with this method. Eq first then time align after.

- Do the RTA settings matter much (16k length, Hanning, 1/24th from memory in the video?), what should suitable settings be?

Sorry, Windows and FFT length are beyond my understanding. IIRC the settings I use have been recommended by John M. At the moment I can't put my finger on a specific post though. Goes back a ways. Put 'em in the RTA settings and left it that way since.
REW's RTA help does provide some insight to the settings though.

- This should still be done for each speaker individually, correct?

I've seen differences of opinion on this, so for bass frequencies try it both ways and pick what sounds best. I was only removing the peaks below 200Hz and the fronts have a very similar response, so together was fine for me. Above 500Hz it is recommended to only use broad filters i.e. for tonal changes and the same filters for both regardless, . I'm thinking also for evaluating the high frequencies separate measurements would be better to eliminate possible effects of comb filtering.
 

dotnet

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Thanks!

I reckon that if periodic noise is used and the FFT sampling window coincides with the period, then a rectangular window would be best, and there wouldn’t be any windowing artefacts. Not sure what settings (in the noise generator, the RTA window and the prefs) are required to ensure that this is the case.
 
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