Hey Guys,
I just made a minor but very interesting discovery. I had a connection established between the “Phono Line Out” on the back of the PhonoPlus V.2 into an “Aux In” on the back of my stereo amplifier so that I could listen (Monitor) while I was recording. Out of curiosity, I unplugged this connection and the background noise dropped by about -5dB (from -65dB to about -70db). Not a lot to get excited about, but directionally correct. After all, you did use the term “tweaking” in an earlier posting. So I quess every little bit helps.
Question: My right and left channel signals with no source turned on register about -5dB different from one another. Is this normal?
if a record has only 45 db snr and he has 55 or better elsewhere with his gear then the vinyl/tape snr is quite important
you cant do better than you start with
if he grounds the thing correctly there should be significant hum
and yes it is vital not just important
and because of the large original phone preamp gain needed
that snr of that preamp will be more important than the snr on the sound card following
I think that’s actually a different switch to what waxcylinder was asking about. Some phono pre-amps have an additional switch which the PhonoPlus v.2 does not appear to have. From a quick look at the manual the switch on the front labeled “Input” is as you say, a switch for changing the input from “phono” to “line”. This switch is very important and you have it set correctly.
I’m probably teaching my Grandmother how to suck eggs (an old English expression meaning that you probably know this already), but the reason for that switch is that some turntables (notably many DJ decks) have a phono pre-amp built into the turntable, whereas traditional high quality domestic turntables usually do not. A phono pre-amp is required for two main reasons: 1) because the output from a magnetic cartridge is so small, it needs to be amplified significantly before being fed into other equipment such as power amplifiers or cassette recorder inputs. 2) vinyl records are created with the treble boosted and the bass much lower - this has several advantages including not throwing the stylus across the room each time there is a loud bass note - but it also means that this pre-emphasis must be reversed when playing the record, and that is what RIAA equalization does. Phono pre-amps are designed to fulfil both functions - to boost the signal from the cartridge, and apply the necessary tone changes (equalisation) to make the record sound right. If you’ve never done this, there’s a little experiment that you can try (this does not help with the job in hand, but it’s safe to try and interesting to do at least once in your life ) which is to switch the input from phono to line. What you will immediately notice is that the volume drops a lot, and it sounds terrible - all tinny with no bass.
Back to the switch that waxcylinder was talking about - some phono pre-amps have an additional switch that allows the input of the phono pre-amp to be matched to the type of cartridge being used. With some cartridges this can make a subtle but noticeable difference. With other cartridges (such as my ortofon, and from what I hear also Grado cartridges) the difference is so small that scientific measuring equipment is required to detect any difference. As the PhonoPlus V.2 does not appear to have this switch, it will be designed to have an average input capacitance load that will suit most cartridges reasonably well - the absence of the switch is unlikely to have a detrimental effect on your set-up.
Grounding the turntable to the pre-amp is the important one. After the initial pre-amp stage, all signals are very much stronger and so less susceptible to hum. In purely analogue systems, an additional Earth connection between the pre-amp and the power amp can reduce hum, but just as often it will increase the amount of hum (a phenomenon known as “Earth loops”).
Something that more often has a beneficial result is to plug all of the system into the same power socket (using a power strip). Unless you have a phenomenally large amplifier (several thousand watts) there should not be any danger of overloading the socket by doing this, but a proper multi-way power strip should be used rather than stacking several of those little multi-way plugs.
I find that quite exciting - but I’m a bit obsessive about audio - but yes, that’s exactly what I meant by “tweaking” - doesn’t make a lot of difference by itself, but it’s in the right direction. If the amp was plugged into a different power socket then it may be an example of the Earth loop issue - if it wasn’t, then it’s just picking up a bit of noise
It’s not unusual, and at such a low level it’s not particularly important, but out of my obsessiveness I’d probably be swapping leads around to see if I could find out where the difference is coming from and if I could get the channel with the higher noise floor as low as the other channel.
Unless it was one of my old favourites with sentimental or collectable value it would be in the trash.
I quite agree about not being obsessive about numbers, but my passion (and some might say obsession ) is with sound, music and what I hear. If you are not able to hear a -50 dBfs broadband hiss through a little bit of vinyl crackle, then it doesn’t matter and we can agree to differ.
Steve,
I am not obsessive about numbers, but I do appreciate fine wine, well engineered autos, etc, including good music. I have never been able to accept mediocrity in anything that I attempted. I appreciate your attention to detail. Your posts have helped to shorten my learning curve and have stimulated my thoughts about several things. Thank you for all the help. I’ll be asking some more questions in the Forum section on editing in a few days.
Charlie
Interesting. I actually monitor while recording via Audacity software fed to my PCs external active loudspeakers - I do have hardware monitoring available on my external USB soundcard - but I prefer to monitor what Audacity itself is getting. In order t do this it is necessary to have the option for “Software Playthrough” enabled in the Recording Preferences (and note carefully that should you ever want/need to record streaming audio then this option will need to be turned off for that).
Yes, as whomper says this is not uncommon. However you can correct for this by using the Effect > Normalize
Unlike Audacity’s Amplify effect which works on both stereo channels equally - the Normalize effect works on each stereo channel independently. Be careful with this though as it can alter the stereo balance.
WC,
I think that you might find the following instructions stated directly from the USB PhonoPlus V.2 manual to be interesting:
MONITORING WHAT YOU RECORD:
Set the front MONITOR SOURCE switch to PREAMP in order to monitor the analog audio coming directly from the preamp. This is useful for auditioning and cueing records or tapes prior to recording. This signal has no latency.
Set the front MONITOR SOURCE switch to CPU in order to monitor the digital audio coming back from the computer. This is useful for playback from the computer and software configuration. See discussion below.
A third position on the MONITOR SOURCE switch is labeled BOTH and it provides a mix of the preamp and computer signals. During typical operation either a record (or tape) is playing back, or the computer is playing back, but not both at the same time. You can listen to either the preamp, or the computer, without changing any settings. You will also be able to hear any computer alert signals while you are listening to the record or tape if the alerts are also routed to the USB CODEC in your computer’s sound setting control panel.
Some recording programs and computer systems provide what is called a “Play-Through” function. This can be performed through software or hardware. When Play-Through is set to ON, the computer will output the audio that is being recorded, at the same time that it is actually being recorded. There is a short delay, or latency with this audio signal. There is also a potential for the computer’s audio inputs and outputs to be inadvertently connected together thereby forming a feedback loop. This can accidentally create very loud and disturbing sounds. Therefore Play-Through is usually set to OFF as the default setting in both software and hardware.
If Software/Hardware Play-Through is set to ON and the MONITOR SOURCE switch is in the BOTH position, then you will most likely hear the original preamp signal together with the computer audio signal slightly delayed, thereby creating an echo effect. This is normal behavior, so while using the BOTH setting it may be preferable to leave the Play-Through set to OFF.
With the included Audacity recording software the Play-Through function can be found under the Audacity menu at: Audacity => Preferences => Audio I/O.
yes, I saw that yesterday when I was looking at the ART site - but as I said, in an earlier post in this thread, I personally prefer to monitor in software via Audacity’s software playthrough - as that way I get what Audacity is getting rather than the signal from earlier in the recording chain via the hardware.
Yes that does give a little latency - but that is not imprtant to me for LP & tape transcriptions or for recording FM off-air. Latency gets to be an issue when you are recording multitrack and you are trying to synch the new track with ones recorded previously.
So how are we getting on with squeezing the static out of your recording chain?
This will probably be the last piece of info relative to Noise Reduction on my setup. I thought about a remark that either WC or Steve made earlier that one of the most vulnerable links in the chain is the weak signal coming from the Cartridge to the PreAmp. So I decided to upgrade the TT to PreAmp cables. I suspect that this is beginning to get really picky, but guess what? It did reduce the SNR by another -5dB from about -62 -64dB down to about -68 -70 dB. So I guess I have done enough experimenting and fine tuning. The Noise Demon that I was plagued with at the beginning of these Postings has disappeared. It’s time to listen to some Music and do so recording.
Thanks,
Charlie
+1
(and I’m lucky to live in a country with very good wine at very affordable prices )
Regarding the initial question about dedicated sound cards… You can read some reviews here on this thread: Sound Card Reviews
For internal dedicated soundcards my personal experience with an Asus Xonar Essence STX is very good (you can read my review about it in the above mentioned thread).
Based on my personal experience with an ART Preamp, I’d say their stuff is pretty good too.
) which is to switch the input from phono to line. What you will immediately notice is that the volume drops a lot, and it sounds terrible - all tinny with no bass.
- but yes, that’s exactly what I meant by “tweaking” - doesn’t make a lot of difference by itself, but it’s in the right direction. If the amp was plugged into a different power socket then it may be an example of the Earth loop issue - if it wasn’t, then it’s just picking up a bit of noise 
) is with sound, music and what I hear. If you are not able to hear a -50 dBfs broadband hiss through a little bit of vinyl crackle, then it doesn’t matter and we can agree to differ.
)