[TheChairGuy]

Finally and this is something I really need to look further into I have found that the lower the circuit noise of the phono preamp the lower the apparent surface noise, I am not totally sure why but I have found this to be a real issue, perhaps someone may have a comment on that one. I found that when I went to full battery power for my system that apparent surface noise took a neat dive and low level musical detail took a nice ascent.

On the whole I think this is a fascinating topic and worth lots of investigation.
Cheers
Zero One

ZO,

Yes, noise (of any sort) seems to ride on the already present surface noise (hiss, click, pops, etc) to make matters worse.  Everything from quieter phono stages to higher quality (ie, quieter) main bearings and motors seems to add or detract from the the ever present surface noise issue.  Most of us (at least those that genuinely enjoy their turntable) have found various ways to reduce the noise in many ways.  You seem to be finding out very much firsthand 

I just read something about the RIAA equalization...which I hadn't known before.  The initial RIAA equalization reduces bass and boosts treble as the record is cut as reducing bass output (which is large, storage-wise) allows for more information to be cut into the grooves.  On playback, your phono stage boosts bass an equivalent amount and pads down the treble.  Depending on how the phono preamp designer designs that playback RIAA curve may effect how noise of various types ultimately sounds.

This may be old news to many of you, but I hadn't known that until I read it yesterday.  Your phono stage may well have more input into the issue of noise than I had previously given it credit for 

John / TCG

[TheChairGuy]

RIAA equalization is therefore a form of preemphasis on recording, and deemphasis on playback. A record is cut with the low frequencies reduced and the high frequencies boosted, and on playback the opposite occurs. The result is a flat frequency response, but with noise such as hiss and clicks arising from the surface of the medium itself much attenuated. The other main benefit of the system is that low frequencies, which would otherwise cause the cutter to make large excursions when cutting a groove, are much reduced, so grooves are smaller and more can be fitted in a given surface area, yielding longer playback times. This also has the benefit of eliminating physical stresses on the playback stylus which might otherwise be hard to cope with, or cause unpleasant distortion.

A potential drawback of the system is that rumble from the playback turntable's drive mechanism is greatly amplified, which means that players have to be carefully designed to avoid this.

That part about rumble is interesting, too.  Of the three primary types of drive systems....rim drive has the highest rumble figures.  It should be that rim drive would have distractingly high rumble figures in a modern stereophonic recording...yet the medium still has many happy audiophiles listening to it (old Garrard, Lenco, Goldrings, etc).  Ah, another topic brewing on that one, perhaps 

[Daygloworange]

RIAA equalization is therefore a form of preemphasis on recording, and deemphasis on playback. A record is cut with the low frequencies reduced and the high frequencies boosted, and on playback the opposite occurs. The result is a flat frequency response, but with noise such as hiss and clicks arising from the surface of the medium itself much attenuated.

A similar preemphasis was done manually at the mixer by the recording engineer with analog multitrack reel to reel recorders during the recording process, however both treble and bass were emphasized. If you playback a blank tape on a multitrack machine with all channels open and all faders full up on your mixer, there is a tremendous amount of rumble, and some hiss on playback. Upon mixing, the engineer would de-emphasize via the mixer Eq. The bass cut lowered rumble, and the treble cut reduced tape hiss. Both resulted in a lower overall noise floor. It wasn't a perfect method, as with the boosted bass, it would introduce crosstalk between channels ( the boosted bass would spill over and be picked up by the playback heads on adjacent tracks), and with boosted treble, it could saturate the tape and cause distortion.

You had to be careful in how you assigned instruments on your tracks on the tape machine. For example, you would never assign a kick drum or a bass guitar near a vocal track, or an track with acoustic guitars, as with those tracks you would be adding gain with compression,(vocals and acoustic guitars nearly always have compression added to make their average volume smoother, and less choppy) and raising the db on low level information.

Cheers

[Wayner]

The RIAA curve was developed to help keep the stylus in the groove when playing low frequencies. The stylus is an electro-mechanical device used to convert mechanical vibrations into electrical signals. The strength of some lower frequencies would actually throw off the stylus before the RIAA curve was developed. As the ability to record dynamics with better microphones came in being the problem became more pronounced. Hence necessity was the mother of invention. The introduction of the RIAA curve came into existance. And yes, it's kind of like a Dolby playback circuit, re-constructing low frequencies and moderating the mid and high frequencies.

As far as record surface noise, it's a simple equation of loudness of noise to loudness of music. If you pay attention, the noise is worse in between songs and when the dynamics of the music passes the noise floor, the perceived noise disappears from the complexity of the music along with hiss. Of course cleaning, type of cartridge/arm/table/suspensions all contribute, for better or worse.

As far as multi-trackstudio recorders, the rumble referred to is a different rumble than the vinyl type. It is mechanical noise from the mechanisms within the recorder itself and is usually associated with flutter which is an undesirable, uneven contact with the record/playback heads.

The reason to isolate heavy instruments from softly recorded instruments in multi-tracking is from an effect called bleed through. Bleed though can also occur between wrappings of the analog tape on the reel itself. The magnetic field on the tape is so strong, it influences the next layer or 2 of tape on top or underneath. You sometimes here the effect on vinyl when you faintly hear the recording start before it actually starts. That is the bleed.

W

[Daygloworange]

The reason to isolate heavy instruments from softly recorded instruments in multi-tracking is from an effect called bleed through. Bleed though can also occur between wrappings of the analog tape on the reel itself. The magnetic field on the tape is so strong, it influences the next layer or 2 of tape on top or underneath. You sometimes here the effect on vinyl when you faintly hear the recording start before it actually starts. That is the bleed.

W

The reason for isolating instruments I gave are valid. Print through and crosstalk are 2 different things. This print though effect happens between layers during tape storage, and on certain instruments (like drum parts) actually plays back like echoes. Crosstalk is between the multi channel heads on the record and playback heads. Those are 2 distinctly different issues.

Cheers

[TheChairGuy]

Man, this turned out to be a very interesting discussion!!

Thanks, gents 

[Wayner]

Daygloworange,

I think we're in agreement about the effect caused by saturated tape with an inherently strong magnetic field capable of influencing adjacent tracks as well as layers on the reel tape. This effect is probably not known to the genreal public at large, aka the guy off the street, but can be considered surface noise as it is not part of the intended recording; it is a cause/effect made by the medium used (incorrectly).

What I was trying to get at is that at mix down, we can usually deal with crosstalk, but can't deal with bleed through. Of course, I'm sure you'll agree that poor recording technics don't usually result in Grammy awards. I also know that cross talk usually isn't a problem unless there are quite passages with 1 or more dominating tracks destroying an attempt at creating a sonic signature, wheather that be natural or synthetic. It's hard to control when it's not supposed to be in the mix and even tougher to get rid of.

This is one of the reasons that bothers me when I hear people complain about one medium vs another. Any idiot can sit behind a mixing board and record some crap. Even mix it down into some form of more crap. I sure many of us think that there are entire albums we could consider as surface noise! It also makes me appreciate the truly remarkable recordings, because I know they just didn't "happen". Some folks actually planned an outcome. Not that ad-libbing is bad as that can be planned for as well.

[Daygloworange]

Wayner,

My intent was merely to clarify, not argue. Yeah, we agree on all the issues with magnetic tape that can wreak havoc on a recording. Analog multi tracks are a bear to set-up and maintain, and are in a constant state of degradation from head wear and so on...They can suffer from microphonics, which add to the noisefloor as well.

Most people of the street are unaware of how much it takes to maintain a multitrack reel to reel. De-magnetizing heads, alignment, bias adjustments, cleaning the heads, capstan, pinch roller etc..

Tapes don't like to be stored. The print through effect happens, and is permanent, and they get noisier with each pass across the heads. The high end starts to roll off.

There are a lot of reasons why recordings are not as good as they can be, some of it is due to the tools, but a lot of it is due to humans being lazy, complacent, careless, and sometimes ignorant, to just plain stupid.

A long time ago, the band I was playing in was given a block of time in a pro studio here in Toronto to record some stuff. Toronto has a number of top notch recording studios. This was at Cherry Beach Sound. The caveat was that it was a hands on internship for some students of a recording engineering program. I won't name it, but it's well known, and charges a lot of money for the 3 year program. These guys were in their 3rd year. It was bad. Real bad. There was so much these guys didn't know about. It was embarrasing to watch them. We were asked not to interfere with the engineering or recording aspect. Although we did intervene during the mixing aspect. It was pretty awful. We let them mix it first, then we redid the mix. Our was way better, but it was still bad. It was still fun for us though. We got to really rip. The students were really impressed with what we had done though, and we got to chat and hang out. They were amazed that we were all self taught.

I was really unimpressed with what was coming out of that school.

Cheers

[Zero One]

Just following up on the influence of phono amps, as stated they really can effect the surface noise.  I feel it is a combination of 4 things, low circuit noise, loading in terms of resistance and capacitance and of course the accuracy of the RIAA equalisation.

The phono amp I am currently using is a diy job and the main circuit is very basic and cheap, but I have paid a lot of attention to shielding and paths/ earthing and the power supply, subsequently it is very very quite, this certainly helped a lot.

But the one thing I did intergrate was variable capacitance and resistance loading via a pair of multi position rotary switches, this acts a bit like a fine tuning control and is very handy for some LPs as I can reduce surface noise considerably on noisy recordings and still have a good sound, of course I know the number of preamps you can buy so equipped is pretty limited but you could DIY like I did for not much money.  The loading is also dependent upon the cart, just because the MM cart is supposed to be 47K doesn't mean it always sounds best at that.

To implement the above phono stage effectively you need very low capacitance in the phono leads, this was a problem for me until rewired the tonearm with external wiring and made some new very short interconnects of my own home brew variety, interestingly the sound became more spacious, but the real benefit was much lower noise and the ability to tune the capacitance as needed, rather than have the interconnect and tonearm wiring dictate it.

Finally and this I have not addressed but I will in a future phono amp build, I feel some sort of adjustable filtration for rumble and noise are a good thing, there have been a few phono amps thus equipped but it should be possible to DIY a really good one, elliot sound products has a very good rumble filter circuit,
Here: http://sound.westhost.com/project99.htm
This is very steep but it would be hard to implement a variable version without multiple boards.

Oh and just a question:  A while back I read somewhere that one of the reasons that low output MC are quiter running is because they don't tend to pick up surface noise as much as it is below the threshold of the system, not sure bout this though I can see some merit here, but this gets me thinking. Most Phono pre for MM are pretty high interms of amplification, but what if the phono amp was in many stages so the first was very low gain/low noise stage, with just enough to perform the equalisation, then the next adding a bit more with some further filtaration and so one. It seems to me that with multiple stages all addressing different issues it should be possible to get something that works really well, I know from doing/teaching LP to CD conversions the results are amazing if you apply the right sort of filtering in the digital domain ( for example really well structured equalisation), but much of this I feel could be done in the analogue doman with a suitable amp.

[TheChairGuy]

Should add that lower inductance will yield less coil noise...so moving coils (lo / medium or high), in particular, will contribute less coil noise than any moving magnet or moving iron (even low output ones) to the overall 'noise' issue at hand. 

Yet, another reason audiophools embrace them.  As well, the expensive ones are well damped internally (the weak mechanical vices must be overcome by zealous use of damping) by some master craftman...probably damping out sympathetic resonances before they ever reach you.

[GBB]

I agree with others who state that the phono stage can have a big impact on the audibility of surface noise.  My pet theory is that this is related to the overload characteristics of the phono stage.  A pop can have a very large transient signal and if your phono stage doesn't handle large transients gracefully then this pop will sound like it lasts a long time and really get in the way of the music.  A good stage will have a quick pop and then quickly get back to the music.  I guess this could also apply to the cartridge / tonearm where the transients could excite some weird resonances, but I think this would be a 2nd order effect.  I've found that as my phono equipment improves, I become less and less aware of surface noise.

---Gary

[Zero One]

Hi Gary

Now that is an interesting thought regarding overload characteristics, I had not thought of that, mmmm I need to look into it. Makes good sense and considering what you see on a waveform when you look at one with clicks and pops I can see some work is needed here.  One issue here is is guess lots of cheap stages run low voltages and have very little headroom, plus their power supplies are not very strong either, many folk say valve stages are the go, I wonder how much of this is due to increased headroom etc.

If you analyse the time taken for a click or pop it is generally very short but it often doesn't sound like it!
Thanks
ZO

[macrojack]

The comments about power supplies in phono stages leads me to wonder once again about battery supplies.
Naturally, nothing could be quieter and the DC current is nice and stiff, so why aren't they everywhere? Is there a downside to battery powered phono? The few reviews and all of the comments I've read have been very positive.

[Zero One]

Gday Macrojack

Yep that is exactly how my phono amp is run. +/-12V from two 7.2Ah SLAs and it does indeed sound better than the mains supply by a margin, quieter and better low level detail.  I feel in my case it is a fair comparison too as the seperate mains supply I have is a really good one, well filtered and all.

One of advatage a lot of folk don't consider though is that batteries are utterly consistent, they sound the same what ever time of day it is, mains supply can be quite variable depending on the time of day and what other items are in use in your area. Around my place anythime after 10.00pm is sweet and around dinner time is awful. As luck would have it phono stages seem most effected by the mains variation!

Ultimately I will build a regulated battery supply running either +/- 15v or 18V (this depends on the chips I use in the next phono amp.  I have used a regulated +/- 12V battery supply for a CD rom based audio player and the results were very very nice, like chalk and cheese compared to the std switchmode so yep batteries rock big time in my world anyway.

As to why they are not used more often in commercial phono pre and amps etc, I can only guess that most makers think there would be consumer resistance or maybe the fact that it is a pretty simple solution that is hard to justify great expense at the retail end may be a factor, the charging issues are pretty simple to solve, perhaps others have a good insight into this, but whatever it works and works well.