# REW help needed ... please



## imported_juiceblrc (Apr 15, 2008)

I am trying to use REW and I have read the instructions, help quides, FAQ's, various REW help threads etc for hours and I am stuck. I am using a radio shack analog SPL meter. I don't have a microphone. Anyways, I have my SPL meter hooked up by a RCA cable to a 1/8 inch adapter to my laptop line in. Then I have a HDMI from the laptop to my receiver to my TV. So, I think I have everything hooked up properly.

In preferences mic/meter I loaded my calibration file and clicked C weighted SPL meter. I see there is a place in preferences soundcard to put the calibration file too. So, I don't know if I put it in the right spot.

When I go to preferences calibrate or to take a measurement I hear the tone and see it in REW (see the screenshot below). However, my SPL meter is stuck at +2.5 DB no matter where I set it at (70 DB or 80 DB etc.). And I get no output on the graph below (same screenshot). But, if I make a loud noise (such as coughing) it shows up on the graph.

When i try check levels I get the same result and the second screenshot shows up.

Then I tried "SPL meter" in REW and then calibrate. Now I do get the correct SPL on the computer screen (3rd screenshot) but my SPL meter in still stuck at +2.5 DB.

My receiver is at -30.

Can anyone help me? THANKS


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## Wayne A. Pflughaupt (Apr 13, 2006)

imported_juiceblrc said:


> I am trying to use REW and I have read the instructions, help quides, FAQ's, various REW help threads etc for hours and I am stuck. I am using a radio shack analog SPL meter. I don't have a microphone. Anyways, *I have my SPL meter hooked up by a RCA cable to a 1/8 inch adapter to my laptop line in.* Then I have a HDMI from the laptop to my receiver to my TV. So, I think I have everything hooked up properly.


It’s possible you don’t have the correct 1/8 plug. If your computer’s input jack is the type that also shares output duties (e.g. headphone) then it’s TRS (tip-ring-sleeve). If that’s the case then your RCA to 1/8” cable probably needs to be TRS also, and most likely it’s only TS (tip-sleeve). Also those dual-purpose jacks often need to be set for either line or mic levels.




> Then I tried "SPL meter" in REW and then calibrate. Now I do get the correct SPL on the computer screen (3rd screenshot) but my SPL meter in still stuck at +2.5 DB.


Something is probably amiss in your description. I’ve never seen an analog SPL meter that reads down to 2 dB, much less one scaled in half-dB increments. 




> My receiver is at -30.


The receiver setting is irrelevant because it is completely dependent on the speakers in use and has absolutely no bearing on in-room sound levels. For instance, with some super-efficient Klipsch speakers, -30 might get you ear-bleeding levels, or merely conversation-level with something like B&W speakers.

Not entirely sure what the issue is, but I’m guessing it’s either with your RCA-1/8” cable, a setting for the input jack on the computer, or perhaps the meter itself has issues. 

Regards, 
Wayne


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## imported_juiceblrc (Apr 15, 2008)

There is more than one kind of RCA to 1/8 inch connector?

Below are links to my adapter & my SPL meter.

http://www.monoprice.com/Product?c_id=104&cp_id=10429&cs_id=1042902&p_id=7189&seq=1&format=2

http://www.radiohannibal.com/.a/6a00d83420a02f53ef017c3219860b970b-pi


As you can see on my SPL meter I have to manually set it to 60 DB or 70 DB or 80 DB etc. But, the needle always stays at + 2.5 DB when I plug it into my computer. If I unplug the SPL meter from the computer it works properly.

I plugged in a microphone from the rock bank video game into my line in on my laptop and I did get sound from the mic so I know the line in works. I have a seperate line in and line out (headphone jack) on my laptop.

Fundamentally I understand how this should work. Its just there is some issue with the hardware or software that I can't figure out.


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## JohnM (Apr 11, 2006)

Try using the other RCA connection (and swap the input channel in REW). The computer is probably carrying a voltage to power mics on one channel of the mic/line in which back-drives the SPL meter, causing the effect you are seeing.


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## imported_juiceblrc (Apr 15, 2008)

Thanks John. 

I will try this out when I get home from work (in about 5 hours) and hopefully it works.


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## imported_juiceblrc (Apr 15, 2008)

Well a few more hours wasted tonight. For such a simple concept I am finding so many problems with the software & hardware.

So, I realized in the first step I am calibrating the sound card only and I don't need the SPL meter. So, I did that. 

My SPL meter still is stuck at 2.5 DB no matter what input device I try on preferences soundcard. Which input should I use? (see screenshot). I tried using the left RCA rather than the right & this didn't help. I tried plugging the RCA to 1/8 adapter into the headphone jack rather than the line in mic jack & I get no signal at all this way.

Somehow I managed to get a subwoofer graph. (see screenshot). Ignore the drop off from 80 HZ to 100 HZ. This is just a crossover issue I fixed.
I actually did a manual graph based on my SPL meter alone and compared it to the REW graph. Some frequencies are close and some are way off. 

I loaded my SPL meter calibration file (RadioShack-33-2055-4050-CS.cal) in preferences mic/meter. The SPL graph is the same with & without the calibration file loaded. The file says it it -13 DB at 15 HZ and -9 DB at 20 HZ. Shouldn't REW compensate for this? 

Any help is appreciated.


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## Wayne A. Pflughaupt (Apr 13, 2006)

imported_juiceblrc said:


> I plugged in a microphone from the rock bank video game into my line in on my laptop and I did get sound from the mic so I know the line in works. I have a seperate line in and line out (headphone jack) on my laptop.


Okay, good to know that you have separate inputs and outputs for the laptop. :T

That video game mic that works with the computer, can you get us a picture of the plug end? I'm going to hazard a guess that it is a TS plug like this:










If that's the case you need an adapter like this:










Regards, 
Wayne


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## Wayne A. Pflughaupt (Apr 13, 2006)

imported_juiceblrc said:


> My SPL meter still is stuck at 2.5 DB no matter what input device I try on preferences soundcard. Which input should I use?


Use the input that you have selected in your operating system’s recording (input) devices. In this case the internal sound card should be selected as the default device, which is probably the one that was selected when you tested the video game mic.

Regards, 
Wayne


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## JohnM (Apr 11, 2006)

You have a room measurement loaded as the soundcard calibration, you need to remove that.

The calibration files on the mic/meter and soundcard preferences tabs affect new measurements, to change the calibration files for existing measurements use the Change Cal button.


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## imported_juiceblrc (Apr 15, 2008)

Wayne,

My rock band microphone has a USB connection on the end that goes to the computer.

Also, when I connect my SPL meter to the laptop through the RCA to 1/8 adapter I get feedback (noise) sometimes.

I did select the internal sound card when I did my latest tests. Its called stereo mix realtek high definition.

When I use the video game mic I have to select logitech USB microphone as my input.


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## imported_juiceblrc (Apr 15, 2008)

John,



> You have a room measurement loaded as the soundcard calibration, you need to remove that.


Are you saying I calibrated my room rather than the soundcard? I used my soundcard as my input and I could only use speakers as an output. When I calibrated the soundcard so sound came out of the speakers. Also, the input/output vertical lights are steady & not fluctuating with the sound in my room.

I have it hooked up 



> to change the calibration files for existing measurements use the Change Cal button.


I found this and it bumps up the graph about maybe 5 DB (at 15 - 20 HZ) and a 2 - 3 DB everywhere else. Nowhere near the 13 DB at 15 HZ my calibration file says. Thats probably why i thought it wasn't working.

Out of curiosity I unplugged everything from my laptop (no wires, no cables, etc.) & yet I got a graph. My subwoofer is not even on. How is this possible? Maybe all of the graphs yesterday were not actually my subwoofer graphs.

I must seem like an idiot here. I understand home audio/video connections well. I setup all of my friends home theatres (TV, receivers, speakers, blue ray, and do all of the cables, set up speakers with SPL meter, etc). But this computer stuff is so complicated!!!


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## imported_juiceblrc (Apr 15, 2008)

Update: I don't think my computer microphone in is a line in or I haven't setup mic in port to act as a line in properly? When I plug in the SPL meter it shows up as a external microphone. 

Maybe this is causing some of my problems? I have no idea anymore.

If it is my problem than does anyone know what part I need to buy to get it to work?


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## JohnM (Apr 11, 2006)

The line in port is typically labelled "microphone" whatever is plugged into it, it's just a label - it might be configured only for microphones though, which would explain the output voltage on both channels which is affecting the RS meter needle. In that case the easy way to get set for measuring is probably to either:

- get a cheap, 2-channel USB soundcard to use with the RS meter, or
- get a MiniDSP UMIK-1 USB microphone (like your rock band mic but designed for measurement)

If you go for the cheap soundcard I'd suggest you avoid the UCA202 as it doesn't seem to get on very well with the RS meter.


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## tpointon (Mar 18, 2013)

Hi. I can sympathize with your situation. John and Wayne have been very helpful to me as I struggled with understanding REW and I still have a minimal understanding; it is a learning process. In fairness, as far as I can tell, REW and this forum are maintained by volunteers and the software is very sophisticated and tries to accommodate a wide variety of devices. I found a few videos online that helped with getting to know REW. What I say below your quote should be heard with caution because I am still a novice.


imported_juiceblrc said:


> I loaded my SPL meter calibration file (RadioShack-33-2055-4050-CS.cal) in preferences mic/meter. The SPL graph is the same with & without the calibration file loaded. The file says it it -13 DB at 15 HZ and -9 DB at 20 HZ. Shouldn't REW compensate for this?
> 
> Any help is appreciated.


REW measures and calculates but doesn't make adjustments to equalize. Nor does it remain active in your sound system once it has done its job. When you have placed your speakers and chosen listening position and made your sweep measurement, the next step is to click on the EQ button and have REW calculate equalization values suitable to your equipment. You probably need some kind of EQ device in your signal path unless your amp has eq capabilities. (My amp has 6 pre-set eq adjustments to adjust for room modes from 40 to 240 hz. I was able with John's help to get REW to provide the needed 6 values). When you press the EQ button, you'll see at the top right a list of devices for which REW will calculate filter values. 

Here is a tutorial I found quite helpful: http://croweaudio.blogspot.ca/2014/03/room-equalizer-wizard-with-jriver-media.html btw if you plan to use a PC or a Mac as sound source, you might consider Jriver Media Center. I tried it and found it very capable, but decided to go with a small Linux box instead of dedicating a laptop or Mac mini t the task of managing my library.

Good luck!


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## imported_juiceblrc (Apr 15, 2008)

John,

Can you suggest a soundcard for me? I don't want to buy one and then find out it won't work for me or it is the wrong one etc. Is the UCA 222 any good? I see you said the 202 is not. Whatever is the cheapest one that will work for me is fine.

My subwoofer amp is the INUKE 3000 DSP and my receiver is a Yamaha HTR 6060 (if you need this info). I don't have a pre-amp. My laptop uses windows 7.

I would consider UMIK mic but I don't really want to spend $100. And again if I run into issues where the UMIK will not work with my laptop/receiver/amp etc. it will just frustrate me more. Can I just plug it into my laptop with the USB cable? Or do I need more hardware? For example, I read I need phantom power (I think I am correct here). I assume I don't have and i don't know how to get it.

tpointon,

Yes this is frustrating. But, hopefully I will figure it out soon. 
With hardware/software issues if one item is not compatible then the whole process will not work. Trying to figure out if/where there is a problem & how to fix it is so time consuming.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Juice,

Reading through your thread again it occurred to me that you never indicated if your mic input could be used as a line-in. Or if it can be, that you changed its designation. John mentioned that the steady-state 2.5 dB issue was probably due to voltage from the mic pre-amp, which reinforces that the input is in mic mode and not line-in. If the input is mic only, and can’t be switched to a line input, then the Radio Shack meter is never going to work and you definitely will need an external sound card.

As for as the UCA222, I’m pretty sure it’s been used before here. Try using the search function to located some threads to see what the consensus is.



imported_juiceblrc said:


> I would consider UMIK mic but I don't really want to spend $100. And again if I run into issues where the UMIK will not work with my laptop/receiver/amp etc. it will just frustrate me more. Can I just plug it into my laptop with the USB cable? Or do I need more hardware? For example, I read I need phantom power (I think I am correct here). I assume I don't have and i don't know how to get it.


 The UMIK is plug-and-play, so there won’t be any issues – at least none like you’re having here. It’ll work just like your video game mic. Phantom power is only an issue with standard mics that connect via a cable to a pre amp. It’s not an issue with USB mics.

Regards, 
Wayne


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## tpointon (Mar 18, 2013)

imported_juiceblrc said:


> Update: I don't think my computer microphone in is a line in or I haven't setup mic in port to act as a line in properly? When I plug in the SPL meter it shows up as a external microphone.
> 
> Maybe this is causing some of my problems? I have no idea anymore.
> 
> If it is my problem than does anyone know what part I need to buy to get it to work?


Not sure how you're getting along, but here are a couple more ideas. Forgive me if you already know this. 

On Windows, if you go to Control Panel and select Sound, you can choose and configure playback and recording devices. The quick way is to right-click the little speaker icon at the right end of the tray (bottom of desktop screen) and select either playback or recording devices. Whatever selection you choose here becomes the Default Device in REW and other apps. More on this in a moment.

Also, I think that if your SPL meter gives a reading when not plugged in via the adapter, but locks in at 2.5 when plugged in, then there must be something amiss with the adapter or the plug. Your earlier picture shows a stereo plug on the adapter, but the output from the SPL meter must be mono (because it's RCA and only one mic). John or Wayne might better know what will happen in this case, but I would suggest getting a straight mono RCA to 1/8 male mono adapter like the one Wayne pictured earlier to rule out unnecessary factors.

Once you're pretty sure you have a legitimate physical connection, I suggest you play a bit with just the computer and the SPL/mike. With the SPL/mike unplugged, Go to Recording Devices in the Sound Control Panel. Your computer likely has an internal mic. I've attached (I hope) a screenshot taken while I was whistling ... you can see the meter reading. I've also shown the Properties box for this device. Note how it has an option "Listen to this device". If you check this box [and click Apply], you will hear the mic signal from this device through the speakers selected for output. Notice also the Levels tab on the properties box; it may also be useful for adjustment. Be careful if you Listen because you may get feedback.

On my screen, the other "Not plugged in" mic is my mic jack. 

If you plug in your SPL/mic it should show up on this sound panel and you should be able to adjust its properties.

imho, until you can get something reasonable under this scenario, there is no point in trying to get REW to work correctly. 

I hope this helps.

btw, earlier there was confusion around calibration. The first kind of cal is calibrating the soundcard. I struggled a bit with this until Wayne advised that it's not likely a major matter with modern sound cards and can often be skipped, which I did. The other cal is mic calibration and it's I think more important because every mic will have its own level anomalies. The mic calibration file tells REW about these mic characteristics.

Wayne and John: Since I value your status here at the shack, I think Juice and I have struggled a bit with REW because the documentation shows signs of having collected details over a period of time. Some of these details may no longer be as relevant (e.g. soundcard calibration). I know it would be a challenge, but documentation that is more task-oriented rather than feature-oriented would help. If there is any project to work on docs, I would be happy to consider contributing to the effort.


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## imported_juiceblrc (Apr 15, 2008)

thanks for all of your help everyone,

Wayne,

yes it looks like my mic in can't be used as a line in so i will need an external sound card.


tpointon

I tried all of that & it won't work. I need an external sound card.

Yes I was confused by all of the info I researched. I was trying to calibrate the sound card. I thought I needed to do it. And I did that wrong too.


For now I measurement my subs response the long way (SPL meter & plotting a graph). I will get a sound card soon so I can try out other settings & get a faster graph


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