Line in Overload

[Wiz]

Hi Steve,
My Aiwa turn table was purchased back in 1982 as part of a micro stereo system. The system was housed in a small chrome rack and comprised of 3 separates of 20w per channel amp (SA-A35H), FM/AM Tuner (ST-R35H) and Cassette Deck (SD-L35H). The amp had phono jacks. I no longer have the full system as it was deemed beyond economical repair with one channel u/s and the cassette chewing up my tapes. I disposed of them only a couple of months back. The turn table which by comparison had been little used, (I mainly used cassettes back then), was safely stored away in its original box and packing. When setting it up for Audacity it only needed a new belt fitting as the original one had gone missing. I am between home stereo systems at the moment as I mainly listed to my music in the car which is fitted with a 6 CD Juke Box. With the way technology is moving I am considering a Brennan JB7. Consequently I do not have a system to plug the turn table into. However, I can listen to the turn table via my PC. Same audio connections as for Audacity use. It plays just fine, no distortion and I have to turn the speaker volume way up to detect the hum that Audacity is seeing in standby. (My Logitec speakers/bass woofer have a separate volume control). It’s so good I may just go back to Vinyl

My 12db dual in line attenuator has just this moment arrived !
http://cgi.ebay.co.uk/RCA-skts-RCA-plug ... 588b9bc937
and I have quickly set it up by connecting it in the o/p audio leads of the pre amp. This has reduced the clipping in Audacity by 99% although the record volume slider is still at zero. No room for adjustment. I was expecting a 25% reduction in waveform but it seems a lot less. I will take some before, (with and without), and after full screen shots and post them shortly so you can see what is happening.

Thanks for your interest all round guys.

[kozikowski]

I was expecting a 25% reduction in waveform but it seems a lot less.

You're talking yourself into a broken sound card or a damaged sound pathway. If you didn't get a reduction to 25% (-12dB), then something is broken. That's consistent with other symptoms -- particularly that business with the volume sliders being all the way down. On any sound card I ever met, that kills the input. Dead.

The only non-broken way you might experience these problems is if the computer were actively fighting you. This is a Win7 machine, right? Did you turn off conferencing services? One of the sound features of modern computers is auto level control.

Windows Enhanced Sound
http://forum.audacityteam.org/viewtopic ... 79&start=0

Koz

[steve]

This does indeed sound strange. As Koz has said, turning the record volume down to 0 should produce a recording of silence (no signal).
I'm wondering if it is a driver problem.
What make/model is your computer?

[Wiz]

Hi Again,
OK so here are some partial screen shots processed in Photoshop.

Koz:
I confirm I have Win 7 Ultimate 64bit. I followed that link in last post and the instructions. Have unchecked ''Allow applications to take exclusive control of this device" but dont seem to have the second box to uncheck i.e. "Enable Audio Enhancements". I have searched all the tabs in that audio box but will look again to be sure. I then tried to record once more ...but there is no change to audacity.

Steve:
Well the driver was one chosen by Win 7 on installtion to a new clean hard disk. Sound Max do not have a 64 bit compatible driver and from my searches of the web they do seem to have some negative comments made about them although not in the same connection as my problem.

My PC came from http://www.bigpockets.co.uk . Similar to this one http://www.bigpockets.co.uk/product.php ... +PC+System
Mine is 4800+ Dual-Core PC. Purchased in Oct 2007. Came in a bundle with 22inch monitor/keyboard/mouse etc. Since upgraded from 2 to 4gb of memory and 2x500gb internal hard disks. It scores about 5.6.

I can see a new sound card looming ...must be extra nice to the wife! Although I do have a birthday coming up
Thanks.

[Wiz]

Sorry - 4th pic did not post so here it is ...

[steve]

4th pic

You might just about get away with that for now. It is a much higher recording level than ideal, but the clipping does not look too bad and may not be very noticeable.
A new sound card is probably the solution. It probably does not need to be an expensive sound card, but it does need to be properly supported by your operating system. I use a Behringer UCA 202 USB sound card (about £25 GBP) with my (Linux) laptop and the recording quality is considerably better than the built in sound card.

[Wiz]

Hi Steve,
Yep - that looks pretty good for now and when it played back it sounds fine. I guess I am at that stage where I need to go lie down in a darkened room and ponder until the nose bleed stops New sound card coming shortly to this PC I guess. I will post the results for anyone following this thread.

In the meantime here are two more pics of Audacity recording with my realtek USB mic built into the web cam and a separate old pc mic plugged directly into the sound card mic socket. Note the record level slider. Must say the latter is not very sensitive and as you can see from the wave form not that clear either (this could also be a pointer to the card). ...not sure how good this direct mic is.

Oh yeah ..also improved the earth to the deck and reduce the slight hum!
Cheers.

[waxcylinder]

The image immediately above shows clearly that you have what is known as "DC Offset" in your recorded signal (the waveform is not centred on zero). This is normally caused by a faulty soundcard.

You can use Audacity to correct this though. Immediately after capture, select the whole project and then click Effect > Normalize
Just check on the box that says "Remove ant DC offset ..." and make sure that the "Normalize ..." box is unchecked (as you don't want apply any amplification at this stage, just remove the DC).

Like Steve I also prefer to use an external soundcard - I use the Edirol UA-1EX (now superseded by the Cakewalk UA-1G). It is a bit more expensive that Steve's device but has the advantage of having hardware gain controls. See this sticky thread on soundcards: http://forum.audacityteam.org/viewtopic.php?f=27&t=9477

WC

[Wiz]

Hi All,
Well I have had that promised lay down in the dark which produced a small eureka moment! I have now connected the 12db attenuator the opposite way round . From the eBay link you can see its two male to two female phono plugs the female ends have a 12db on them - male ends are blank. Previously the male attenuator plugs went into the female pre amp phono sockets, now the males of my 1 metre audio leads fit there instead - the attenuator is reversed. Physically the attenuator is closer to the sound card i/p sockets. I am now able to record without clipping but with the record slider set at a max of 1. Acceptable for now. Pre amp female skt to audio lead male phono > male audio lead to female attenuator > attenuator male to 3.5m adapter. Hope that makes sense - may be I have been at this too long .. but it works!

Thanks for the info on DC offset and the fix. I will take all that on board.

I will definately look into a new sound card and the possibility of a USB type. I have as yet to read the link you gave but will do before purchasing.

Thanks for all the help and interest guys!

p.s. a final pic of the best work around.

[steve]

That looks much better.
How does it sound?
How does it sound on really quiet bits?

Web Cam mic:
Clear signs of DC offset - The "silence" between words is clearly below the centre line.

With basic Mic into sound Max:
The "spikes" at the beginning of each word look like what happens if you're blowing on the microphone - need to take care that air from mouth/nose does not hit the microphone. (see this topic: http://forum.audacityteam.org/viewtopic ... 28&t=49854 )

I use the Edirol UA-1EX (now superseded by the Cakewalk UA-1G). It is a bit more expensive that Steve's device but has the advantage of having hardware gain controls.

I think it probably also has better A/D, D/A converters in it.