Subject:Getting Rid "Inside Pipe" Sound From Recording

Posted by: BobWard

Date:8/5/2010 9:03:01 AM

I recently got Sound Forge 10 with Vegas Movie Studio 10.

I am converting some very old (40-year) casette tapes to digital format for preservation purposes. These are tapes of radio transmissions I recorded while flying combat missions in Vietnam during 1970 - so the radio transmissions are a little "staticy" to begin with.

The converted digital files frequently have certain portions of the transmissions that sound like someone is talking inside a pipe - other portions sound normal. The "pipe" effect is non-existant when playing the tapes on my casette and listening to them on my speakers, i.e., it seems to be something that was created as part of the digital conversion process.

Not being familar with all the editing tools in Sound Forge, is there a certain tool that would be useful in getting rid of this "pipe" sound effect?

Thanks,

Bob

Subject:RE: Getting Rid "Inside Pipe" Sound From Recording

Reply by: MarkWWW

Date:8/5/2010 9:28:39 AM

It's very difficult to offer advice in this sort of situation without hearing the actual audio. Without hearing the actual audio I'd just be guessing what you mean by a "pipe" sound and my guess might be completely different from what it actually sounds like.

If these recordings aren't confidential, post a couple of short examples somewhere where we can download them - ideally a short section (a few seconds should be enough) showing the problem, and also a section where the sound is OK. Once we've heard what is going on I'm sure someone here will be able to advise on what to do about it.

From your description (the problem occurring only in the digital version) it seems that the problem is being created when the digital version is being created so it would probably help if you described in detail exactly how you recorded the digital version.

Mark

Subject:RE: Getting Rid "Inside Pipe" Sound From Recording

Reply by: musicvid10

Date:8/5/2010 11:09:41 AM

"The "pipe" effect is non-existant when playing the tapes on my casette and listening to them on my speakers,"

Then you've got some internal feedback going on in your computer. Go to Windows Recording Properties, and mute all inputs except the one you are using (line in?) I bet you have "What U Hear" or something similar enabled.

Subject:RE: Getting Rid "Inside Pipe" Sound From Recording

Reply by: BobWard

Date:8/5/2010 1:38:36 PM

I used the "Vinyl Recording and Restoration tool" to do the digital conversion. That may have automatically done some audio corrections that it felt were warranted, when in fact such corrections may not have been needed.

The "pipe" sound is similar to what I hear when my grand kids play with these long map storage tubes and talk into one end of the tube - kind of puts a little bit of a revereration effect to their voice.

I will try recording again without using the "Vinyl Recording and Restoration tool" and see if that cures the problem.

I will report back.

Thanks for your responses.

Bob

Subject:RE: Getting Rid "Inside Pipe" Sound From Recording

Reply by: roblesinge

Date:8/5/2010 3:13:51 PM

Sounds like some EQ was applied by the restoration tool and that created the artifacts you were hearing. Always record raw and then apply effects afterward.

Rob

Subject:RE: Getting Rid "Inside Pipe" Sound From Recording

Reply by: Chienworks

Date:8/5/2010 5:40:58 PM

I've noticed that effect sometimes with a bad stereo cable. If the ground goes bad then the channels end up being combined inverted to each other, which is the classical vocal-remove method. It sounds exactly like someone talking a long way away through a pipe.

I'm guessing you may be going through a 1/8" plug into the computer. These are notoriously bad at sorts and breaks. Try a new cable. For that matter i would assume these recordings are in mono to begin with, in which case recording only one channel would help.

Subject:RE: Getting Rid "Inside Pipe" Sound From Recording

Reply by: BobWard

Date:8/5/2010 6:48:17 PM

Yes, I am using a 3-ft cable (new from Radio Shack) with 2 RCA plugs on one end and the single 1/8" plug on the other end which goes into my laptop "Microphone" port.

Yes, the recordings are Mono, so I guess I could remove either the right or left channel connection.

I will try the "raw" recording tonight.

Bob

Subject:RE: Getting Rid "Inside Pipe" Sound From Recording

Reply by: musicvid10

Date:8/5/2010 7:43:04 PM

I rarely repeat myself, but did you check your internal recording settings for feedback loops, as I posted?

Subject:RE: Getting Rid "Inside Pipe" Sound From Recording

Reply by: BobWard

Date:8/6/2010 8:35:10 PM

I tried, but I could not find any tabs or menus that were labeled "Windows Recording Properties". Where would this be located?

Bob

Subject:RE: Getting Rid "Inside Pipe" Sound From Recording

Reply by: Steven Myers

Date:8/7/2010 3:36:08 AM

To get at the recording properties in Win XP:

If you have the speaker icon in your tray, double-click on it.

Or Control Panel | Sounds and Audio Devices.

Subject:RE: Getting Rid "Inside Pipe" Sound From Recording

Reply by: BobWard

Date:8/7/2010 2:50:03 PM

I am using Win 7, 64 bit.

I did double-click on the speaker icon. Under the Recording tab it lists 'Microphone - Realtek High Definition Audio, Default Device'.

Is there something else I should be looking for?

I did play the cassette tape through my stereo system and it sounds fine, with none of the pipe reverberation sound that I am hearing after recording it through Sound Forge. So the problem is definitely being introduced during the digital conversion process.

Bob

Subject:RE: Getting Rid "Inside Pipe" Sound From Recording

Reply by: Steven Myers

Date:8/7/2010 3:28:27 PM

In Win7, right-click the icon and pick Properties. It isn't as handy as in XP, but you can get from there to all the input devices and levels.

Subject:RE: Getting Rid "Inside Pipe" Sound From Recording

Reply by: BobWard

Date:8/7/2010 6:27:05 PM

When I right-click the Speaker icon, Properties is not an available option. The only way I can get to a Properties tab is to:

1. Rt-Click Speaker icon
2. Select "Recording Devices"
3. Select Recording tab
4. Select Microphone (Realtek High-Def Audio)
5. Click on the Properties tab
6. Now 6 tabs appear: General, Listen, Levels, Enhancements, Advanced

I don't see anything that indicates multiple audio inputs are present.

Bob

Subject:RE: Getting Rid "Inside Pipe" Sound From Recording

Reply by: musicvid10

Date:8/7/2010 7:21:01 PM

So you're plugging your cassette into the mic input?

Subject:RE: Getting Rid "Inside Pipe" Sound From Recording

Reply by: BobWard

Date:8/7/2010 7:32:50 PM

I am plugging my casette tape deck into my laptop through the Microphone input jack on the laptop.

Bob

Subject:RE: Getting Rid "Inside Pipe" Sound From Recording

Reply by: Chienworks

Date:8/7/2010 7:46:17 PM

Ewwwwwww.

Is there a line input? If not, you'll probably need an attenuating adapter. The tape deck is putting out something close to 1 volt RMS while the microphone jack is expecting about 1/1000th that amount. The attenuating adapter will drop the signal level to the right amount for the mic jack.

Also, almost all mic jacks are mono. Plugging the stereo cable into it could cause some issues depending on the physical configuration of the jack, including the cancellation problem.

Subject:RE: Getting Rid "Inside Pipe" Sound From Recording

Reply by: BobWard

Date:8/7/2010 8:31:40 PM

This is a stereo jack. Two RCA plugs go into the tape deck and the 1/8" stereo jack goes into the laptop mic input connection.

Everything I have read indicates that this is the proper way to make the connection to convert tape casettes to digital files. I have not read anything about needing attenuators.

My next option is to use my Canopus digital converter box to do the conversion directly from the tape deck to the computer hard drive, without using any intermediate software such as Sound Forge Studio. I used that box to convert all my old VHS tapes - so I think it will work for audio tapes as well.


Bob

Subject:RE: Getting Rid "Inside Pipe" Sound From Recording

Reply by: musicvid10

Date:8/7/2010 8:51:35 PM

You need to disable any microphone "boost" and set the mic level way down -- so that peaks don't go much above -6dB in the Sound Forge meters. With the kind of voltage your tape deck is putting out (about .7V), you need to be really careful.

Your problem might be caused by hitting input limiting with a too-hot signal.

Subject:RE: Getting Rid "Inside Pipe" Sound From Recording

Reply by: ChristoC

Date:8/8/2010 2:25:06 AM

> My next option is to use my Canopus digital converter box

Given choice of Canopus or Mic Input, there's no choice - Canopus is very likely setup for exactly the optimum level and impedance required for tape deck.

Subject:RE: Getting Rid "Inside Pipe" Sound From Recording

Reply by: jackn2mpu

Date:8/8/2010 5:36:08 AM

"This is a stereo jack. Two RCA plugs go into the tape deck and the 1/8" stereo jack goes into the laptop mic input connection.

Everything I have read indicates that this is the proper way to make the connection to convert tape casettes to digital files. I have not read anything about needing attenuators."

This is part of your problem. Your original recordings are undoubtedly mono and you're trying to play them back on a stereo cassette deck and then recording THAT into a mono input on a computer. All built-in mic jacks on a computer are mono. That old tape is worn and the mono path on the tape is wandering up and down between the 2 tracks on the head. That's going to cause the signal to vary between the two channels. When you plug the adapter cable you're using into the computer you're basically only picking up one channel, not both, because the hot connection is only picking up the channel connected to the tip of the jack. The second channel is the smaller sleeve connection just behind the tip and the return/ground is the longest part of the sleeve furthest from the tip.

With that signal wandering around between the two tracks on the tape head the signal being picked up by your computer is also changing in level. That's part of your problem. The second is you really need to either use an attenuator between the cassette deck and your computer or lower the output of your cassette deck.

If by some odd chance your computer's mic input is stereo then with that old tape you're getting phase issues between the two channels.

Jack

Subject:RE: Getting Rid "Inside Pipe" Sound From Recording

Reply by: BobWard

Date:8/8/2010 9:56:07 AM

Problem is now solved. I connected the tape deck to my desktop computer which has a line input port, unlike my laptop which only had the mic input.

I recorded the tape to the despktop (using Sound Forge) and the digital copy sounds like an exact replica of the original - no reverberation, no pipe sound, etc.

So trying to use the Mic input on the laptop was the problem. I connected a microphone to the laptop and did some test voice recordings and they sound fine.

Thanks for all the advice guys.

Now my next task is to clean up some of the static and hum that was in the original 1970 radio transmissions. Any recommendations on the best tool to accomplish that?

Bob

Subject:RE: Getting Rid "Inside Pipe" Sound From Recording

Reply by: Chienworks

Date:8/8/2010 4:57:16 PM

Sound Forge Pro? If so you should have Sony Noise Reduction included. Regular noise reduction can do wonders for the hum. Click & Crackle filter will amaze you with the static.

Subject:RE: Getting Rid "Inside Pipe" Sound From Recording

Reply by: BobWard

Date:8/8/2010 6:27:20 PM

Actually I have Sound Forge Studio 10. But I see it does have the Audio Restoration tool, which has several adjustment sliders. It also has a Noise Gate tool. I will have to play around with those and see what I can do.

Thanks,

Bob