sub hums if I turn on SPL meter

[subby]

Hi, I'm about to calibrate my SVS PB10.

But my sub starts humming if I turn on my spl meter. If I turn the spl meter to 80 db it hums so hard my ears almost pop.

I also have trouble calibrating the soundcard. If I measure and the sweeping sound comes it only measures about -78db fs. But almost whole my house depresurizes from the sweeping sound. is that to load or to quit?

I'm using the M-audio Delta 44 soundcard btw.

[brucek]

But my sub starts humming if I turn on my spl meter

This would indicate that the cable ground is bad. Are you using an RCA type connector at the meter and a 1/8" stereo phono connector at the soundcard with a proper shielded coaxial type cable between?

I also have trouble calibrating the soundcard. If I measure and the sweeping sound comes it only measures about -78db fs. But almost whole my house depresurizes from the sweeping sound. is that to load or to quit?

When you do a soundcard calibration there should be no sound at all, since it involves hooking a single stereo jumper cable from line-out to line-in of the soundcard. Where is the 'sweeping' sound coming from?

brucek

[subby]

I've hooked up my cables exactly like it shows in the picture with the help files.

I've hooked up the cables like you said just from the 1 line in to the line out and I don't heard the sweaping sound anymore indeed. But I still only get a measure of 53 db wich is still too low.

I Can hear everything from the sub that the spl meter hears. If I hold the spl meter to my chest I can actually hear my heartbeat.

[subby]

Ok, it was indeed a bad connection. The coacial input was to thick at the edge for the input on the RS spl meter (wich is kinda turned more inside the spl meter itself. But I took a nife and cut a piece of the edge away and now the distorting rumble is gone.

now only remains the problem with the soundcard calibration where the measured sweep seams to be to low (only 53 db fs). So I get that warning every time after the sweep.

[brucek]

now only remains the problem with the soundcard calibration where the measured sweep seams to be to low

Tell me about the cable and connectors you're using for the loopback here.

brucek

[subby]

well, the cable should be quit decent. it's just a coax cable with a phono to 1/8 RCA plug at both ends.

I have more doubts about the sound card or maybe the soundcard settings. As I said I have the M-audio delta 44 soundcard wich has a break out box with 4 line ins and 4 line outs. the break out box is connected to the soundcard. you think this soundcard should do the trick? I don't want to spend any more money as needed if this soundcard already is all I need.

http://www.m-audio.com/products/en_us/Delta44-main.html

[brucek]

well, the cable should be quit decent. it's just a coax cable with a phono to 1/8 RCA plug at both ends

This confuses me somewhat.

The soundcard (which should be fine BTW) uses a breakout box that has 4 line-out and 4 line-in channels using 1/4" TRS (for balanced) or 1/4" TS (for unbalanced) connections. In your case you will be using a single channel for REW. You will also have to be aware of the monitor mode, which you want to shut off.

So, tell me again how you have channel one configured and wired (connector and cable) to setup the soundcard cal? Why do you have phono to 1/8" ?

brucek

[subby]

lolz, guess I might be confused with all the different connections

It's indeed coax to 1/4 I'm using, that's the connector.the cable is just coax.

[brucek]

guess I might be confused with all the different connections

Yep, no problem.

I think you only need to use channel one with a TS unbalanced 1/4" connector and cable between line-out and line-in. I assume that your equipment will be unbalanced and (of course) the meter is unbalanced, so this should work fine.

Be sure to shut down the monitor mode of channel one before attempting anything. This is a standard problem with soundcards and REW. The monitor mode allows the simultaneous monitoring of the sound while recording, and it should not be used when using REW. Be sure this is disabled before attempting the soundcard calibration.

Do you think this may be your problem in trying to create a soundcard cal file?

Does REW recognize your card and allow you to select the channel in question on the Settings page?

brucek

[subby]

No, I can perfectly save a soundcard cal file. It also reconizes my soundcard and I can choose both left and right input channels

at the input and output device I have the option to choose between Delta 44 1/2, Delta 44 3/4 or Delta 44 multi. At the intput device I only have line-in when I choose delta 44 multi. with Delta 44 1/2 and 3/4 I only get wave. at the output I can choose SPEAKER in all 3 options though.

I unselected the monitor mixer option but I still don't get below 59 db fs.

I don't really know what you mean by unbalanced TS connector though.

[brucek]

I don't really know what you mean by unbalanced TS connector though.

Unbalanced TS is a two position 1/4 " connector (shown in the bottom of the two connectors) with the Tip and Sleeve connected as opposed to balanced TRS (top picture), which is a three position Tip, Ring, Sleeve connected. Your device allows both, and automatically compensates for the correct levels (like a BFD).

You would use TS, since the meter is unbalanced and likely your equipment (receiver) is unbalanced....



brucek

[subby]

Oh, you mean I'm going to have to buy new coax to TS 1/4 connectors?

I doubt the problem lays there

[brucek]

Oh, you mean I'm going to have to buy new coax to TS 1/4 connectors?

How do you propose to connect an RCA unbalanced SPL meter to the soundcard without an unbalanced TS connector?

brucek

[subby]

But were not even in that stage yet. The problem is now that the soundcard is measured to low. The spl meter isn't connected yet, only line in with line out. Or has it anything to do with the soundcard being unbalanced?

I wonder why this isn't mentioned in the REW guide that you need a ST 1/4 jack if it's so importent.

[brucek]

But were not even in that stage yet.

Yeah, I realize that, and you're correct. I was only responding to your statement that you would have to purchase new connectors. I meant that in the end, there is no getting around it. The meter is unbalanced, so you'll eventually require the unbalanced hookup.

The problem is now that the soundcard is measured to low. The spl meter isn't connected yet, only line in with line out. Or has it anything to do with the soundcard being unbalanced?.

Yeah, the soundcard cal is definitely the first problem at hand, and that can be accomplished with a balanced (or unbalanced) conection between line-out and line-in of one channel.

Are you able to make that connection and select it in REW. In other words, is the channel one selected when you select LEFT in REW or RIGHT. Try both.

I wonder why this isn't mentioned in the REW guide that you need a ST 1/4 jack if it's so importent.

Because 99.9 % of soundcards simply use a 1/8" unbalanced connector which supports left and right channel. Your breakout box is unusual.

brucek

[Wayne A. Pflughaupt]

subby wrote:

The problem is now that the soundcard is measured to low. The spl meter isn't connected yet, only line in with line out. Or has it anything to do with the soundcard being unbalanced?

I wonder why this isn't mentioned in the REW guide that you need a ST 1/4 jack if it's so importent.

1. If the soundcard is unbalanced you don’t need a “ST 1/4 jack.”

2. Probably because few of us home audio types have pro sound cards.

Regards,
Wayne

[subby]

I use about 4 phono to 1/4 jack sockets right now. Do I have to replace them all 4 with a ST unbalanced phono to 1/4 socket or should one be enough to unbalance the signal?

[subby]

Ok, I found a 1/8 jack to 1/4 TS jack plug. So I took 2 stereo cinch cable that leads to a 1/8 ST plug and put the 2 SRT plugs on the cinch cables and plugged them both into a line in 1 and 2 input. the other end I put the 1/8 ST plug into the 1/4 ST plug and put it in a line out. Now REW measures 9db witch should be enough. If I do it the other way around it doesn't work anymore though.

But do I still ned to buy 3 other ST plugs or is one enough? And is it alright that I had only 1 ST plug into the line out but 2 stereo cables in the line ins? they're both the same cable though.

[brucek]

a 1/8 jack to 1/4 TS jack plug. So I took 2 stereo cinch cable that leads to a 1/8 ST plug and put the 2 SRT plugs on the cinch cables and plugged them both into a line in 1 and 2 input. the other end I put the 1/8 ST plug into the 1/4 ST plug and put it in a line out.

I'm somewhat confused by what you're telling me.

Hopefully when you say 1/4 ST you mean 1/4" TS (Tip Sleeve) connector and when you say 2 SRT you mean, quantity two 1/4" TRS (Tip Ring Sleeve) connector? And does 1/8 ST mean 1/8 " phono stereo? I'm also not familiar with the word cinch cable either I'm afraid.


Here's the simplest solution.

You need to get - quantity two, adapters like this one at Radio Shack - very cheap. It's an RCA to 1/4" TS adapter.



They accept a standard RCA cable (which is a mono coax interconnect with RCA connectors on the end). Everyone has lots of them lying around.

Simply connect channel one line-out to channel one line-in of your breakout box as seen below, by using the two adapters shown above and an RCA cable.



brucek

[subby]

Well if you explain everything like that. I must say I have done what was your instructions from the start. So I'm doing everything right.

Think I got unbalanced confused with unbalanced. Because the picture what you show of that coax to RCA is what I've been using from the beginning. Cinch cable is the same as a phono cable. sorry about all the spelling mistakes though.

Actually I just meant mini jack that weant into a 1/4 jack (with the 2 black rings, so that must've been a balanced one). funny, the soundcard got calibrated with that cable but after that the cable was full of noise and I couldn't check the levels of my subwoofer properly. Also my soundcard couldn't hear my spl meter during the calibration (and that was connected just as you told, coax cable with RCA plug). the spl meter works fine though.

I think the problem might be with my soundcard because I tried all different settings. I might e-mail M-audio and ask about the question. But they don't know REW probebly. I just hope I don't have to spend money on another sound card.

[brucek]

I must say I have done what was your instructions from the start. So I'm doing everything right.

OK, that's great - I just wanted to make sure we were on the same page.

So, with just the one mono unbalanced cable hooked between line-out and line-in of channel one, and REW recognizing the presence of the card, and selecting Right or Left in REW (depending on whether Right or Left corresponds to Channel one of the 44 breakout box), are you able to get a decent soundcard calibration? and save that file as soundcard.cal............

brucek

[subby]

It still only get's to 59 db fs wich should still be too low according to REW, but I can save it as a soundcard.cal file.

[brucek]

And how does the file look?

Can you post it?

Example - here's my soundcard file. Set the Graph axis limits from 2Hz to 25Khz and check the soundcard box....



brucek

[subby]

This is what it looks like if I push ok when I get the error message.

[brucek]

That shows an oscillation. Be sure you have all the 'effects' including equalizers, surround, etc turned off.

Are you not able to increase the Wave and Output level and the sweep level higher and get a decent signal into the line-in?

brucek