Noise tests on my audio recording setup

Following BillW58’s recent thread on noise removal tests (see ) and some email correspondence I have had recently with another forum user (patcurci) on a related matter I have been led to do series of tests on my recording setup.

Update: following discussions on a recent thread by user brgavato (see: ) I have added a further piece of kit into my recording chain. I am now also using a passive switch 3-in, 1-out to switch between my input devices. See below in the thread for review/tests.


  1. Audacity 1.3.12 running on Dell Dimension 2400 desktop with Windows XP-HE
  2. Edirol UA-1EX external USB soundcard
  3. ARTcessories DJ-Pre11 phono preamp
  4. Technics SL150 DD TT with SME 3009-11 (Improved) tone arm
  5. Technics FM tuner St-X902l
    All the equipment is located in close proximity on or near my desktop – all of it is powered from a surge protected multi-way drop, itself powered from a single wall socket.
    All the test recordings were done with a null signal input and then amplified 25dB and played back on my attached active speakers at maximum volume. Numbers at the end of each test set-up are the available headroom for further amplification (after the original 25dB amp.). Note: the higher the number => the less noise on the track.

Test Results

  1. Edirol soundcard attached to FM tuner (with tuner turned off) - loudish hiss generated 36.7
  2. Edirol soundcard on its own, RCA leads isolated - hiss, but nowhere near as loud as with the FM tuner attached 49.7
  3. Edirol soundcard on its own with RCA plugs touching - loud hum (disguises/hides the hiss) 18.1
  4. Edirol soundcard connected to ART pre-amp, with preamp unplugged - very slightly lower hiss than in 2 50.0
  5. Edirol soundcard connected to ART pre-amp, with preamp unplugged & transportable phone in nearby cradle/base-unit - same as 4 50.0
  6. Edirol soundcard connected to ART pre-amp, with preamp on - loud noticeable hum, hiss not audible 20.9
  7. Edirol soundcard connected to ART pre-amp, with preamp on, but careful placement of leads and unit - much reduced hum and hiss noticeable again 36.4
  8. As 7 but with TT RCA leads unplugged and earth wire removed - loud hum and hiss, worse on R channel 20.2
  9. As 7 but with TT earth only connected to ART - sounds same as 8 but waveform looks “cleaner” 21.2
  10. As 7 with TT RCA leads connected but no earth - nasty loud rasping hum, masks hiss 7.1
  11. all re-connected properly and careful lead placement - sounds same as 7

1 & 2 above => that my FM tuner contributes a little noise even when turned off, on standby
2 & 4 => that my Edirol generates a little hiss
4 & 5 => the transportable phone and base unit in close proximity appear to generate no additional noise
7 => that the ART (or the TT/arm/wiring/cartridge) adds some hum to the hiss provided by the Edirol
6,8, 9 & 10 => my right channel is noisier than the left
6 => that careful placement of the RCA and earthing leads is important in reducing noise
10 & 9 (&7) => proper TT earthing is absolute critical (but I hope we all knew that already)

And do remember to turn down the speaker volume when the tests are finished - otherwise you may blow the speakers!

I need to point out that the “noise” in all these tests is totally undetectable with normal recordings (and my aging ears) even when listened to on high quality playback equipment and that therefore I make no attempt to remove the “noise” from my recordings as I do not wish to mess with or remove any of the real signal any more than necessary.


Do you really mean amplified 25 times (27.96 dB) or amplified 25 dB (about 18x)?

It will take me a while to digest the results, but I generally agree with your comments at the end.

That said, my (apparent) mania for noise reduction is not aimed at reducing or eliminating the noise generated by the electronics, but to find an effective means to reduce the vinyl surface noise, which is always louder than the hiss from the electronics. Also, in some cases with recordings from the pre-Dolby era, one can hear the tape hiss on the recording. I’d like to reduce that as well.

Note that I say “reduce” not “remove”. I rarely go for more that 12 dB of noise reduction, and will settle for 9 or even 6 dB if the final result is acceptable to my ears.

– Bill

I couldn’t agree more. In the real world, Noise “Removal” is a misnomer that leads to unrealistic expectations.
I think there is a touch of irony in the fact that noise reduction is most effective when the noise level is really low to begin with.


it’s a fair cop - you got me :blush:

Yes I do mean amplified 25 dB (as per the Amplify dialog box) and NOT 25x as you correctly point out - sorry.


Update: original post corrected following Bill’s comments

I have added a new piece of kit into my recording chain. As I record from multiple input sources I was getting fed up with continually re-plugging the RCA leads from my USB soundcard to my various input devices – plus I was conscious that this will lead to degradation of the plugs/leads over time.

Skytronic 3-way Switching Unit - Ref: 128.234 RCA stereo sockets 3-in and 1-out (manufactured in The Netherlands)

Taking it out of the box the first impressions are that it is a sturdy well-built piece of kit. It weighs over twice as much as the Cables4All device that I also considered but is also smaller (13x7.5x4.5 versus 20x11.9x4.7) so I’m guessing that the Skytronic is more sturdily built. It has 4 non-slip rubber feet and the buttons feel good and secure in operation. The supplied documentation is somewhat sparse, but hey what do you need.

I ran some bench tests before assembling it all in its proper location, testing:

  1. my FM tuner (no signal - turned off, but in standby) connected direct to my Edirol UA-1EX soundcard
  2. my Technics TT and ART preamp connected direct to the Edirol
  3. FM tuner => Skytronic switch => Edirol
  4. TT => switch => Edirol
  5. and finally just the switch => Edirol, with the switch set to position 3 with nothing connected on #3 input (but with TT & tuner connected on #1 & #2)

At normal recording volumes there was no discernable noise. Amplifying with Audacity by 25dB still gave no audible noise, but a small indication of noise on the waveform. Amplifying with Audacity by50dB noise can be heard on 1-4 but not 5. The waveforms show similar noise amplitudes between the 1&2 recordings and th3 3&4 recordings. The 5 recording shows a very tiny amount of noise, barely audible, and it requires amplification by a further 25dB to show up properly on the waveform. So I have to agree with the reviewer Martin Turner on Amazon that “In operation this is beyond whisper quiet …”

What extremely little additional noise there is could just as easily be down to the additional cabling/plugs. And I think that over time I will get less noise than if I was repeatedly unplugging and re-plugging the RCA leads to my various output devices. (Plus it has enabled me to place both the Edirol and the switch on a high-ish shelf well away from my cats! )

All in all I would recommend this device if you have different input sources that you need to record from. Note that the USB soundcard is not essential – if you have a line-in port on your computer and a good on-board soundcard then you could go straight from the Skytronic switch to your computer.