Almost ready to start using REW

**salvasol** · **04-18-08, 03:38 PM**

Please be gentle with me ...

After been posponing for a long time the use of REW, I'm decided to start my system performance check.

I just need to get the external card (I have all the rest); and here is my dilema: I know about the Soundblaster card, but I'm looking for a cheap card that I can use to transfer audio and video to my computer; I have a lot of VHS home movies that I want to transfer to DVD; and is my understanding that with the Soundblaster I can use it for the audio only ... I don't want to get two cards.

I need your suggestions to get a card that can be used to transfer audio/video and can be used for REW.

I just downloaded the sinewaves, I will start measuring manually until I get the audio/videocard ... this will serve me to learn more about the system response, to get an idea of the deficiencies and see what I need to correct ...

I forgot: to test using the sinewaves; This is what I'm going to do: Set SPL the same way as when calibrating (75-80db); play sinewaves, write down the measurements for each frequency and then make a graph of the responses, Right??? ... this will give me an idea of the system response, Am I correct???

Please feel free to give all your suggestions ...

**Wayne A. Pflughaupt** · **04-18-08, 05:23 PM**

I suggest posting your “what soundcard?” question over at our Computers Forum, since the one you want involves more than just REW use.

Quote:

I forgot: to test using the sinewaves; This is what I'm going to do: Set SPL the same way as when calibrating (75-80db); play sinewaves, write down the measurements for each frequency and then make a graph of the responses, Right??? ... this will give me an idea of the system response, Am I correct???

That’s about it. If you find that any of your readings are really low – say below ~65 dB, raise the volume and take them over.

Regards,
Wayne

**salvasol** · **04-18-08, 06:54 PM**

Thank You

**salvasol** · **04-19-08, 12:51 AM**

I did it ...

Using SPL and audio test tones courtesy of HTS

... I manually entered the measurements in REW and I got this graph ... can somebody please tell me, Is this good or bad???

Green line was the measurements sending the sub output to front speakers and subwoofers and red line was just using the subs ...

I need to check the receiver EQ (I don't remember if I boosted any frequencies, I'm sure this will affect the system response) ... I can wait to run REW

I also measured 250Hz, 333Hz, 417Hz, 500Hz and 100Hz ... but I didn't include them on the graph.

Volume was at reference (-5.0db in my case

)

**brucek** · **04-19-08, 01:29 AM**

Quote:

can somebody please tell me, Is this good or bad???

Measure using a target of 75dB.

Use vertical axis of 45dB-105dB and a horizontal axis of 15Hz-200Hz.

Quote:

Green line was the measurements sending the sub output to front speakers and subwoofers and red line was just using the subs

Don't understand this statement..

brucek

**salvasol** · **04-19-08, 12:33 PM**

Quote:

brucek wrote:

Measure using a target of 75dB...

How can I do this ... I'm not using REW (just to make graph); I'm manually checking the levels with RS SPL meter ... I set my volume at reference (75db) and measured the level output for each frequency test tone (10Hz, 12Hz, 14Hz, etc.)

Quote:

... Don't understand this statement... brucek

What I mean is, that I have the option on my receiver to send the sub signal to front speakers, Sub or both ... I measured with signal send to Sub only (red) and with signal send to both (green).

**salvasol** · **04-19-08, 12:41 PM**

Sorry, Brucek ... I found this post from you at another thread; now I know what you mean...

Quote:

...

I would set a target level of about 75dB at 50Hz.

Then take readings from about 16Hz to 200Hz at 1/6th octave points.

brucek

**jerome** · **04-19-08, 01:34 PM**

Quote:

salvasol wrote:

How can I do this ... I'm not using REW (just to make graph); I'm manually checking the levels with RS SPL meter ... I set my volume at reference (75db) and measured the level output for each frequency test tone (10Hz, 12Hz, 14Hz, etc.)

Don't you have a sound card on your PC? Even a cheap one, an integrated one for instance? That would get you started with the cabling and the general use of REW. Later on when you received your new sound card, then you only need to calibrate and adjust the levels with the new card.

Also: why would you want to send the low frequencies to your main speakers when you have subs to do the same job? In addition, if you use the LFE output then your subs will take care of ALL the low frequencies, not only for the main speakers.

**brucek** · **04-19-08, 01:35 PM**

Quote:

I set my volume at reference (75db) and measured the level output for each frequency test tone (10Hz, 12Hz, 14Hz, etc.)

Your readings are all around 100dB though, not 75dB.

Quote:

I measured with signal send to Sub only (red) and with signal send to both (green).

And adding your mains increased the level at 10Hz by over 20dB. Does that seem right to you?

brucek

**Wayne A. Pflughaupt** · **04-19-08, 01:44 PM**

Quote:

salvasol wrote:

Sorry, Brucek ... I found this post from you at another thread; now I know what you mean...

The 50 Hz reference was only relevant for that thread because 50 Hz was a good mid-way point between his peaks and depressions.

That said, 120+ dB- yikes! At least lower the volume so you don’t blow up your sub! In your case, I’d use ~80 Hz for the 75 dB Target reference.

Regards,
Wayne

**salvasol** · **04-19-08, 04:16 PM**

Quote:

jerome wrote:

Don't you have a sound card on your PC? Even a cheap one, an integrated one for instance? That would get you started with the cabling and the general use of REW. Later on when you received your new sound card, then you only need to calibrate and adjust the levels with the new card.

Yes my laptop has an internal sound card, but if read correctly the instructions on REW ... I can't use the microphone input; and that's all I have on the card

Quote:

... Also: why would you want to send the low frequencies to your main speakers when you have subs to do the same job? In addition, if you use the LFE output then your subs will take care of ALL the low frequencies, not only for the main speakers.

My subs are not that great, frequency response is 35Hz - 150 Hz

... my main have the same minimum frequency response 35Hz - 20Khz; and on my receiver I have the option to send the sub output to Front speakers or Subwoofer or Both ... and that's what I'm doing (in my mind is like using four subwoofers

)

**salvasol** · **04-19-08, 04:42 PM**

Quote:

Wayne A. Pflughaupt wrote:

That said, 120+ dB- yikes! At least lower the volume so you don’t blow up your sub! In your case, I’d use ~80 Hz for the 75 dB Target reference. Regards, Wayne

That's why there was a burning smell yesterday when I was doing the test ...

The graph didn't seems right to me, I've seen other but they're different ... that's Why I asked if it was correct. Remember I'm still learning how to do things

Well here is my new graph; I set the SPL to 75db @ 50Hz (I just saw the post that is better to use 80Hz) ... like I said before, I have the option to send the LFE/Sub signal to front speakers (red), front + subs (green) or just the sub (blue) ... please explain me What this graph means ... i'm

**Wayne A. Pflughaupt** · **04-19-08, 10:46 PM**

Quote:

salvasol wrote:

That's why there was a burning smell yesterday when I was doing the test ...

Cute!

Quote:

... please explain me What this graph means ... i'm

Hmm... Well if you ask me, I think it means you’re going to have seven years of bad luck, followed by seven years of prosperity.

Just kidding. Seriously, it doesn’t “mean” anything. It is what it is. It’s the response of your mains and sub in the room, simple as that.

At those speaker locations and that measurement location, at least.

That said, notice that your blue sub-only plot looks a bit different than your red front speakers plot, but your green combined plot looks just like the red one. This tells me that your mains are overpowering your subs. IOW, your subs really aren’t contributing anything useful. Maybe you should turn them up?

On the other hand, it appears your mains have better extension than your subs. Have you tried corner-loading the subs?

Regards,
Wayne

**salvasol** · **04-20-08, 03:07 PM**

Quote:

Wayne A. Pflughaupt wrote:

[font="Comic Sans MS"]... notice that your blue sub-only plot looks a bit different than your red front speakers plot, but your green combined plot looks just like the red one. This tells me that your mains are overpowering your subs. IOW, your subs really aren’t contributing anything useful. Maybe you should turn them up?

Do you think it can be because I connected the mains in parallel, and according to an online review my RXV 2700 is sending 272 WPC to the front ???

When you said: "turn them up" I'm sure you mean the volume/Gain on the sub amp, Right??? ... when I calibrated the speakers I set the sub 5db higher than the rest (80db).

Quote:

... it appears your mains have better extension than your subs. Have you tried corner-loading the subs? ...

I agree with you about the speaker extension, like I said I think the 272 WPC has a lot to do with it ...

One of the subs is placed in the corner (Velodyne VRP 1000) and the other is inside the riser near the back wall (is like 2' from the rear corner); this is an Infinity TSS 750 sub.

I know that I need better subs, but that for the future ... I already

more than I should at this time

What is your suggestion, Should I change something to get a better response or is this way okay???

By the way, I wasn't kidding about the smell ... even my kid ask me: What is burnning???

**jerome** · **04-21-08, 01:53 AM**

Quote:

salvasol wrote:

By the way, I wasn't kidding about the smell ... even my kid ask me: What is burnning???

I suggest that you check your speakers and/or power amplifier(s). You probably have damaged one or the other. Did you find the source of the burning smell?

If the smell comes from your speakers then I would check the inductors for burning marks...

**salvasol** · **04-21-08, 12:45 PM**

Quote:

jerome wrote:

I suggest that you check your speakers and/or power amplifier(s). You probably have damaged one or the other. Did you find the source of the burning smell?

If the smell comes from your speakers then I would check the inductors for burning marks...

No I didn't look for the source of the smell ... I think it was the receiver that was overheating

I used my equipment yesterday (to run more test, but his time at the right volume) ... everything worked fine

**salvasol** · **04-21-08, 12:46 PM**

Can I use this for REW??? ... (this will aslo serve me to transfer my movies according to description).

Is a mono output ... so, I think this is fine, Right???

Amazon.com: USB NTSC Tuner / Digital Video...

Shack Stores	Affialites
Electronics Store	Aperion Audio	Axiom	Best Buy	Blockbuster Video
Home Theater Systems	Buy Electrical Direct	Buy.com	Cambridge	CinemaNow
Home Theater Receivers	eBay	Musicians Friend	Newegg	OneCall
Movies and Music	Radio Shack	SonyStyle	TigerDirect	ToshibaDirect
Canada Store	Vanns	Walmart	zZounds
U.K. Store

Advertisement