Electric guitar hum and buzz, how did the engineers using tape manage to avoid it?

cfg

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Occasional hobbyist here. I have done a little recording in the past with budget gear (Reaper, Saffire 6, and a handful of half decent mics) and have struggled to get guitar tracks without buzz or hum. I've never heard a dead quiet guitar amp yet, as there is always some minor amount of hum or buzz, and my tracks likewise have some noise I don't like.

I googled the question, and some answers included surgically editing out the parts before and after the guitar parts, and the fact that amp noise will be masked once when there are other instruments playing. I get that, but here's what I can't figure out. Snipping parts is fine for digital recording, but there's a ton of music from the 60's, 70's, and 80's that was laid down on tape, where presumably editing out sections leading up to and just after certain guitar parts was not an option, and they're quiet. I can't believe every hi gain guitar player from days gone by had a dead silent amp, and yet there are thousands of songs where no hiss, hum, or buzz can be detected when the guitar is not playing and the other instruments are also relatively or completely quiet.

So, just how did the engineers of old using tape manage to avoid hiss, hum, and buzz from hi gain amps? Or, if they did capture some of it, how did they get rid of it with gear of the day? What am I missing?
 
1.) And the most important one...figure out why your amp/guitar is so noisy and what needs to be done to minimize it. If it's the electric, fix it or get some additional equipment that will clean it up.

I've never had a problem with amp noise when recording. First off, my electric is clean, and I have additional equipment to regulate and clean it even more...and everything is wired appropriately (no ground loops). The amps are all good quality, well built...and when the occasional pedal suddenly kicks in a lot of noise...I either find a way around it, sometimes by adding a ground wire or changing order and/or position...or I get a different pedal.
Of course, sometimes it's the guitar...single coils are always noisy, and you try to find a location and position in the room where it's minimal, though with small studio space, and lots of computer gear or just other gear in general, it's sometimes hard to find that quiet spot with a single coil guitar.
It's easier to clean things up before you record...then after.

Otherwise...


2.) With tape, when mixing...you hit the mute button on a track when there is no audio if there is background noise on it.
3.) Turn your amp volume up louder...so when you play, any noise will be buried that much more.
 
Dirty electricity isn't good.
Yes, single coils do pick up hum. But there's a thing called signal to noise ratio. In short, as mentioned by miro, turn it up. When you play, noise is gone, when you're not playing roll off the volume on your guitar.
If your amp has a lot of self noise, have a tech look at it, and/or look into cleaning up the juice coming out of your wall.
 
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Guitars with processing make lots of noise when they aren't playing, but amp distortion used in the early years wasn't as savage as modern distortion devices. Amps did hum - listen to early prog rock live tracks and you can hear it leaking into other open mics. In the studio, despite gates being available, the usual technique was simply to leave the fader down until the instrument was needed. However, my memory of my own recordings in the 70s was that I never really had hum and buzz issues. Mind you, the level of RF rubbish around then was so much lower. My old 30W tube amp and Strat was perfectly clean until I bought a Fuzzface and discovered distortion. From then on, faders and mutes were the way it worked. Moving faders and automation was for us, out of the question, but soon it was mutes, mute groups, then computer controlled mute groups and we were off. In some mixes in the early days, the entire band had hands on a fader.
 
Kepex gates. I don't use gates often for guitars, but even a gate pedal can help in noisy situations. The thing about the old recordings that most often gets ignored is the fact that they were mostly recording using small combos not stage gear. The size came from the tone , the micing and to a certain extent, the room. Guitar shielding, amp power and all the rest of the previously mentioned causes all have to be addressed first. Using an sm57 or similar dynamic mic is not just for the sound of the mic, it's also because dynamics are so much less sensitive making it easier to mic louder sources without picking up as much of the amps inherent noise. If you can't get exactly the right balance of low background noise to good play levels then sometimes it's just easier to set up a noise gate
 
Thanks to everyone for the replies. When mutes or faders were used, was it necessary to bounce tracks? I'm trying to get a better idea of the process of using a mute button or fader. My imagination tells me it would look something like this: A given guitar track with some noise in between parts is listened to, and sections needing muting or fade down are noted, track is played and simultaneously recorded onto another track while the engineer manually mutes the sections requiring it using notes as a guide as to when to hit the mute. Is this correct?
 
Some numbers.
I was going to check the Mex Strat I recently screened so this has shifted my arse..

The barr A was played through an HT-20 head+Greenback. The level at my chair was thereabouts 90dBC on a cheap meter.

Mic was a Prodipe TT1 (about the size of an SM58 and about 1/2dB more sensitive) and was about 2" from the speaker fret.

AI, NI KA6 with gain at 11 o'clock, the chord was hitting -25 to -15dBFS.

Turning guitar VC to zero gave just the amplifier noise at -74dBFS

The spectrum shows the amp noise only. The 50Hz peak is I am sure power traff induced into OPT. The stock 20 is about 10dB worse than this so I modded mine. Never had anybody else be as fussy tho! Tge 100Hz peak is almost certainly OP valves not bang on balance. Not that I could hear either him in the room. Wind up guitar and it gets worse of course.

So, there you have it. With THIS amp and THIS guitar I can get a S/N of about 55dB and with a bit of gain tweaking and getting guitar further from amp and PC, easily another 5dB.

60dB is about the S/N of a good (but not best) old tape machine so "they" did not have too much to do because it would not have been heard.

Last thought. When my Behringer BCA2000 worked it had a remarkably good noise gate in it. I bet there are some STONKING software ones now?

BTW. if that "A" sounds a bit odd? No top E! It pinged off whilst tuning.
Dave.
 

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Since I'm lacking recording chops I'll have to spend some time studying your post ecc83, but thought I'd mention my #1 amp is an HT40 loaded with an early EVM12L (I tried a Greenback before, and that speaker also sounded terrific in the ht40.) I've owned probably 30 or more amps over the years, and still own (among others) a Triamp MK2 and a DR103, but I only play the HT40.

BTW, you say you modded the 20. Can you say what you did to it?
 
Heh! I have boggled you with my decibabble and you confound me throwing amp model #s at me!

I only really know Blackstars. The HT-40 was one of their best sellers a few years ago. Close cousin to the 20 but totally fixed biased whereas the 20 is partial cathode biased(or have I boggled you again?!)

All the HT-series were mainly the brainchild of Cliff Brown, ex Soundcraft engineer and a very clever chap. Now makes the boutique 633 amps. Cliff was given the brief to design good, solid reliable amps but not in the cost arena of the Artisans nor the all singing, all dancing Series Ones. I think he did a bang up job?

The HT-5 was pre- Cliff and, although just a 5W amp, is not a "budget" design having most of the features you would expect of a top studio/small gigging amp, multiple speaker impedance jacks, FX loop (at 2 levels) and, almost never seen on a valve* amp, a headphone socket. The Five also has the lowest hum and noise level of practically any guitar amp yet made. The used to specc out at 80dB below 5 watts!

The hum mod on the 20? Well, I COULD tell you but then.....! Ha! Easy, you just rotate the OPTraff but you need to make up a special bracket. As I say "I" could hear is and it pissed me off. Son, the guitar player wasn't bovvered!

*Forgot! I think it is pretty well known now that most of B's amps are "hybrid" in that a mix of valves and op amps are used?

Dave.
 
A given guitar track with some noise in between parts is listened to, and sections needing muting or fade down are noted, track is played and simultaneously recorded onto another track while the engineer manually mutes the sections requiring it using notes as a guide as to when to hit the mute. Is this correct?

You can do it that way, though that adds one generation loss with tape....but that's not what I meant.
During mixdown...the mutes are applied in real time as you mix from a tape deck. Often more than two hands are needed.
Another option is to set up a gate either during tracking, or on the tape track during mixing, and gate out the noise, though with some tracks, it's not always precise if you have a lot of varying levels/dynamic, as you can only set the gate to one thing.

If you are working in a DAW...just cut/delete the noise in-between.

That said, I would be curious what level of noise you really have...because I can't believe that all you amps have always had a lot of noise.
If you're mostly talking about the more typical low-noise "hiss" that some amps have...that should be easily masked out by louder playing level....and during mixing, it will be masked by all the other tracks that are playing....so it may only need to be dealt with in spots where the other tracks drop back or out of the mix...the real quiet spots...which would be easy to mute or gate or edit...etc.
 
I had no knowledge of Brown, so the information is interesting and greatly appreciated. Although I'm confused by you saying the 40 is fixed bias as I just biased my amp. There's a bias pot (50mA spec.) and a balance pot. Regardless, I actually have three Blackstar's. The first one I bought was an HT1 (no verb). Terrific little amp. Then I bought an ID:Core Beam (another super fun amp that I play late at night) and then the HT40. The funny thing is, the PCB of the HT40 looks more like something you'd find in a desktop computer. I don't have a clue what all those circuits are doing, but whatever they're doing it works, because I just don't play any other amp these days.
 
You can do it that way, though that adds one generation loss with tape....but that's not what I meant.
During mixdown...the mutes are applied in real time as you mix from a tape deck. Often more than two hands are needed.
Another option is to set up a gate either during tracking, or on the tape track during mixing, and gate out the noise, though with some tracks, it's not always precise if you have a lot of varying levels/dynamic, as you can only set the gate to one thing.

If you are working in a DAW...just cut/delete the noise in-between.

That said, I would be curious what level of noise you really have...because I can't believe that all you amps have always had a lot of noise.
If you're mostly talking about the more typical low-noise "hiss" that some amps have...that should be easily masked out by louder playing level....and during mixing, it will be masked by all the other tracks that are playing....so it may only need to be dealt with in spots where the other tracks drop back or out of the mix...the real quiet spots...which would be easy to mute or gate or edit...etc.

Thanks, that helps. I think my amps are relatively quiet. I am indeed talking about the low noise hiss that even the best amps have in some small degree. And it makes sense that other instruments would mask hiss. I think I got good answers on how songs recorded on tape manage to be hiss free. I'll have to work on my recording techniques too.
 
It may also be worth mentioning that mix automation came in during the 1970's which allowed volumes and mutes to be programmed. Another technique (if you didn't have automation) was to mix a song in sections and then edit the sections together. If you needed lots of changes at one particular point you could stop the tape just past the point, make the changes, rewind the multitrack and then carry on.
 
I had no knowledge of Brown, so the information is interesting and greatly appreciated. Although I'm confused by you saying the 40 is fixed bias as I just biased my amp. There's a bias pot (50mA spec.) and a balance pot. Regardless, I actually have three Blackstar's. The first one I bought was an HT1 (no verb). Terrific little amp. Then I bought an ID:Core Beam (another super fun amp that I play late at night) and then the HT40. The funny thing is, the PCB of the HT40 looks more like something you'd find in a desktop computer. I don't have a clue what all those circuits are doing, but whatever they're doing it works, because I just don't play any other amp these days.

"Fixed" bias. I just KEEP messin' wid yer head don't I!? Yes, it's a paradox. Fixed bias* is, as you say, usually variable (except for some tight-ass designs that want to same 50cents or so!) and "we" do it properly with a 1R sense resistor in the cathode (with either a protection diode or a big ass resistor, A100) . In the 40 the bias is derived from a dedicated traff winding and, rare this, a FULL wave rectifier!

The Blackstars came in for a lot of stick for their hybrid design and I will agree, PR could have been handled better perhaps (but! There is only ONE kind of bad publicity?) I shall bang on a bit about my take on the design philosophy...

Front end is an op amp, why? Well, it is lower in noise than a triode input (hiss) and there is buggerall hum, no AC heater current* The IC is fed from 12-0-12 volt supplies (15,15 in the S Ones) so it can handle around 10 volts peak input which is way more than an ECC83. Op amps also practically live for ever and never go "miccy".

The pre amp OD sounds are produced virtually ALL by the valves, the other ICs are used as buffers and tone control circuits and FETs used for signal switching, much more cost effective than relays and MUCH quieter (in the sense that relays put clicks on the signal rails)

"You can't please all of....." of course but the amps sell well, the company has weathered two recessions (and looks like we are in for another biggy!) so they must be doing something most people like?

*The Artisans are the only amps using AC heating. A design decision was made to go over to DC because it has several benefits.
Hum is eliminated and this is especially important for a PCB design (the PCBs look like computers because that is a cost effective way to make them. 'Puter MOBOs are pretty reliable?) .

Valve life is increased because they are somewhat protected from mains V variation. The absence of AC means that cathode/heater leakage matters little (BIG hum!) and modern valves are often not good in that respect.

*Cathode bias on the other hand IS fixed! By the value of the resistor, in fact if you ever come across a VERY early Artisan 15 or 30 shout! Needs a mod.
How did you set bias balance? We had a special test circuit but putting Mk1 lug against the speaker and setting for minimum hum is just as good. N.B. can use a scope but AUDIBLE hum and visual hum often do not correlate.
It could be argued that a bias balance pot in a guitar amp is Lilly gilding but there you go!

Dave.
 
I set bias balance with the trim pot by measuring offset on each tube (pin 8 and ground) independently until reading was the same, then the overall bias. The balance was pretty close to start with, but I say gild that lilly. I didn't quite understand what you were saying about the MK1 lug against the speaker, and if you're able, it would be great if you could explain it a little more clearly.

I had a very strange problem recently. After I bought the amp, I switched out the stock tubes for a pair of NOS British Mullard's, dual getters. The amp ran dead quiet for months, then all of a sudden I had hum, lots of it. Unfortunately, I couldn't place the exact time the problem started as I didn't play for a few weeks, and I wasn't sure I could trust my memory that the amp was as quiet as I thought I recalled.

Now the only potential catalyst I could recall was leaving the amp on standby overnight, twice, but I'm not sure that would mess up the tubes. In any event, then the problem manifested to where the amp would start hum free for about a minute, then a small pop, and then the hum would kick in. I monitored bias during one of these episodes. The bias slowly climbed to 67mA, then the pop, and the bias immediately fell to 33mA with an accompanying drop in volume. I then dropped in a pair of TAD EL34's, used, but seemingly in good shape, and the hum problem resolved itself. I biased and balanced, and was just glad to have the amp back to sounding the way it should. I'm still puzzled how one or two NOS Mullard's could go south, but it is what it is.

OP amps, SS rectification, IC's, and the switching power supply would turn off many so-called amp aficionados, and in fact, just a year ago I might have let my prejudices prevent me from considering the HT40 as a main amp, but because I had recently stumbled onto the very decent small HT1, I was somewhat aware of Blackstar's sound, and then I stumbled on the HT40 at a fire sale price in a pawnshop which I couldn't pass up. I figured I had picked up an amp I could easily flip if I didn't like it, but within a few weeks I knew I had found the sound I had been groping for for over 33 years. Very strange really. The only problem is that it's one very heavy amp with the EVM12L and its huge magnet and cast basket.

I'm curious as to what your connection to Blackstar is. Can you say? With that much information you must work (or have worked) for them, or know someone who does.
 
Ha! "Mk1 lug". Ear close to speakers so you can hear the hum that results from OP valve imbalance.

The problem with the NOS Mullards just might have been linked to leaving the amp on standby for an extended period? The S Ones and most of the HT range do not shut HT off for SB function, instead they bias the OP valves to cut off (or very close, 1 mA or so). It is therefore possible,(but unlikely IMHO) that the 34s did not like having HT on anode and G2 and heaters running but no anode current. I can only say I never had nor have ever read of such an issue.

This form of SB function comes about because the DPR control in the S Ones does not allow HT to be switched off. Blackstar then turned necessity to an advantage. You probably know the amp is silent UNLESS there is a jack plug in BOTH input and speaker jack? This affords some protection against that bête noir of valve OP stages, no speaker plugged in! N.B. The HT-20 does not even HAVE a standby switch!

Me? I answered an ad in the local rag in 2005 after being "let go" for months. Long/short, they wanted someone who knew valves (would not kill hisself) to do servicing and help with "lab" work in the development of new products.

As a new company they could only offer me part time 20hrs a week but in fact, after tax I was about as well off as I had been at the stingy bastards I was with previously HELLERMAN TYTON Northampton yer &^$£"$r!

Unfortunately after just a few years I developed cancer and had to give it up. I made a 100% recovery and even though I was by now into retirement, the OEM Ian Robinson tempted me back to help out in the "lab"

Then! Wife went suddenly very ill and so I had to leave and become a carer. I shall always remember my time at Bs with affection. Great bunch of guys (well mosty, TKWIM!) and gals.

I am of course well behind in their latest products (would love more info on the Unity bass circuits!) but will help out as far as I can with stuff I worked on. Please do not however ask for schematics. I know most stuff is now on the web but it did NOT come from me!

Dave.
 
Has anyone mentioned just trying the ol' "stand up and turn slowly until the hum and/or buzz is nearly gone?" That's what I do in-studio when I'm getting a buzz, assuming it's not a broken amp or cable or switch or something causing a really loud 60-cycle hum...if it's just the "normal" level of buzz one gets from a guitar plugged into an amp that's cranked, just try the turning trick before you start tracking.

And as far as what everyone else has said in terms of tape and real-time mute-pressing (I call it "mix-dancing." If you've never seen any footage of say, a mid-70's Steely Dan record being mixed, I'd hunt some down on YouTube. 5-7 guys standing around the board at all times, each with their part to "play." When someone messes up, they have to start all over. It's amazing), the only trick I didn't see mentioned was punching in silence where the guitars aren't playing. They'd literally just record silence in those sections.
 
Has anyone mentioned just trying the ol' "stand up and turn slowly until the hum and/or buzz is nearly gone?" That's what I do in-studio when I'm getting a buzz, assuming it's not a broken amp or cable or switch or something causing a really loud 60-cycle hum...if it's just the "normal" level of buzz one gets from a guitar plugged into an amp that's cranked, just try the turning trick before you start tracking.

And as far as what everyone else has said in terms of tape and real-time mute-pressing (I call it "mix-dancing." If you've never seen any footage of say, a mid-70's Steely Dan record being mixed, I'd hunt some down on YouTube. 5-7 guys standing around the board at all times, each with their part to "play." When someone messes up, they have to start all over. It's amazing), the only trick I didn't see mentioned was punching in silence where the guitars aren't playing. They'd literally just record silence in those sections.

That's what I'm doing. My SSS-Strat puts off a nice buzz going straight into the interface, which is above my PC tower. When I angle
the head straight at the PC it disappears completely - and there's a decent amount of arc to play with so I can bob around some while
I'm playing. I also put a limiter on it set very low.. just in case. My bass is silent.

I've been in one of those 5-man fader rodeos - it was a hoot. Lots of fun, actually.
 
the only trick I didn't see mentioned was punching in silence where the guitars aren't playing. They'd literally just record silence in those sections.

Its pretty easy to 'spot erase' noise on tape. Especially with an autolocator or other such functions. Always found that much easier than dong the console mute/unmute dance.
 
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How did they avoid it?

The best way is to have gear that does not buzz or hum in the first place. Secondly they would have gated the signal using good quality gates that you would barely notice were working. If there were long gaps between playing you could record silence on the tape. Manually mute the track on the console, before automation there were often many pairs of hands working faders and mutes, the mixing was almost a performance LOL. And later when there was automation no problem by chasing the noise on the fade out. I have done all of the above in the past.

Funny I have a Marshall JTM30 valve amp in the studio that gets used a lot by guitarists to track without bringing in ridiculous 100 watt tops and quad boxes, and I noticed the other day that it had an acoustic hum stating to happen and was generating a little more speaker hum than it did, so I sent it in for a check up and the tech replaced the Filter Caps, varnished the power transformer and cleaned all the pots, the thing is near silent now.

Alan.
 
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