Phono Preamp Tube Rush

It’s unfortunately a fact of life for us lovers of vacuum tube phono stages. Worse if you listen loud, like I do, of course. I’ve had the Hagerman and currently own a Herron. Both are about as quiet as low-rush noise as you’re going to get, especially the Herron. The Hagerman is a really nice sounding stage with romantic beautiful sound; I see why you love it. Sometimes I miss it and wish I’d kept it, but I moved on to a VAC that is better, though for much (!!) more money. If you like the Hargeman you’d probably love VAC phono stages, even the ones built into their integrateds and preamps.

The ONE factor you can play with to combat rush noise is to get a cartridge with a higher output level - that allows you to lower the preamp volume, and audible tube rush will reduce proportionally. The other thing to note is that is you’re loading your cartridge very heavily, you will lose some signal and that will allow tube rush from your phono stage to creep back up in relative level.

If you're using a low output MC cartridge, using an outboard SUT with a higher gain (and phono stage in MM mode) will also allow you to combat tube rush noise. 

Between songs you hear LP groove noise.  Lift the tonearm and I bet it gets much quieter.  Then you will hear self-noise from input resistance and tubes.  

An good SUT can wonders, as they are mostly noiseless.  But not always.  If they use too thin of wire the resistance gets too high and becomes the main source of input noise.  The low-end Cinemag was like this (maybe they have since updated).

Mostly what you hear is noise from resistance, not tubes.  

I use a number of Deccas inc the SG and cannot recall this issue with my Croft 25R with Shuguang Black 12AX7LS. But then again, between vinyl roar, and tape hiss on older recordings, you’re making me second guess what I feel is a near silent amp. In my book, if there’s no trace of 60 or 120Hz anything, I’m golden!

It is difficult to build a high-gain phono stage for mc cartridges using tubes. A SUT or a SS head amp (like a Marcof) is the answer (feeding a tube mm stage).

I used a BD's Cinemag 3440-A through my EAR 834 P through the mm stage with a Dyna D3 and had no issues.

I still have the SUT if there's any interest.

hagtech, In explaining that SUTs can be a source of noise, you wrote, "If they use too thin of wire the resistance gets too high and becomes the main source of input noise."  What???  Where does that idea come from? To begin with, the primary of a SUT is seeing the miniscule output voltage of typically a LOMC cartridge, like 0.5mV of AC, or less.

My tube phono ( Quicksilver ) is as quiet as any solid state preamp that I have used!

I use a Herron VTPH-2 (not 2A) in conjunction with an AT-ART9 LOMC cartridge rated at 0.5 mv, with the Herron's stock tubes and no loading plugs. If I turn the volume control in my system to a setting slightly higher than I would ever use (which is quite loud; some classical symphonic recordings I listen to can produce 105 db peaks at my 12 foot listening distance) the hiss produced by the phono stage is only audible within about 1 foot of the speakers.

In saying that, though, I should point out that I believe the Decca London Super Gold cartridge mentioned by the OP is a high output cartridge, and while the moving magnet input stage of the Herron is indeed tube-based its LOMC input stage is FET-based (i.e., solid state).

@lewm I believe what hagtech is referring to is Johnson noise, that would be produced to some (not necessarily audible) degree by any resistance.

Regards,
-- Al

Those are 2 popular units.,one of which i've tried.-Herron. No noticeable tube rush at "reasonable" volume, from the listening position. 

If you're expecting SS, absolute quiet during blast sessions,in between cuts-good luck on that. Even the finest at unreasonable volume, have some leve of  hiss. 

Real amplified music is noisy. A Fender or Marshall at idle won't win awards for quiet.

@dhcod- You mentioned having tried new tubes.     Were they graded for low noise?    You probably already know, but, just in case- some tube vendors grade their tubes.    Some don’t.   ie(check what’s said, regarding, "Platinum Grade" and, "Kevin’s Stash"): https://www.upscaleaudio.com/pages/grading-matching

I have little if any tube rush with my Luxman.

One of the keys to having low noise in a tube phono stage is careful selection of low noise NOS tubes.

As mentioned above, tube rush is a fact of life with tube phono stages...to a greater or lesser extent. Even with matched NOS tubes, the amount of rush will depend on how much gain is applied to the tube.
When i hear folks say they have no or very little tube rush, that tells me that they are not listening to the speakers that close....or at very high levels. Push up the gain...and there comes the rush.
I have fought this battle for years, as my CAT preamp has had a number of different NOS tubes rolled into it..and there is always some tube rush...IF i listen very closely to the speakers. Not bothersome to me, and I do NOT hear it once the music is playing, but it has always made me question how much is actually lost in the presentation of the music vs. a ss device that is perfectly quiet ( if there is such a device)...vs how much is lost due to the beauty of tube phono stage reproduction vs. ss phono stage reproduction. I still way prefer tubes.

I have a Musical Surroundings Nova Phonemena (solid state with a DC power supply) and a Manley Chinook (tubes).  If I turn up my preamp to the 12 o'clock position with nothing playing, I hear no added noise with the Nova.  There is an audible increase in the noise level with the Chinook, but it's not overwhelming.  I don't notice the additional noise from the Chinook when I'm playing records and that 12 o'clock position on the volume dial is about as loud as I listen. 

Which pre do I like better?  The Chinook.  So yes, some noise is the price you pay for tubes.  I have low noise tubes that I purchased from Brent Jessee and I think they helped, and I'll take a little bit of noise to get that tube magic.

Thanks for the helpful responses!  Thanks mulvely and daveyf especially because I think our experiences are similar. I do listen to my Harbeth M30.1s in the near field which I'm now realizing is another factor. 

I can certainly identify with this topic and the advice so far has been spot on consistent with my experience.  I too have a Herron VTPH-2A and noticed tube rush only a foot or so from the speaker when volume is up quite loud and BEFORE needle touches the vinyl.  I have found a bit of success (in my quest to lower the phono noise floor) by moving from a 0.3mV cart to a 0.5mV and by dialing gain and loading through a Zesto SUT.  I've had discussions with Roger Modjeski about possible noise reduction using his SNL tubes (at ~$100/ea) in the 1st gain stage of the Herron. He thought it might lower the noise floor a few dB but he said it's hard to say.  Haven't pulled the trigger on new tubes yet.

Almarg, You are very kind to answer for Hagtech.  Maybe he will also answer for himself.  Just in case he was not talking about "Johnson noise".  Apparently every conductor creates Johnson noise, It's not a property inherent to transformers only.

I also have the VTPH-2A. Great phono stage. I am using a Hashimoto HM7 SUT with it. At one time, I did have a little tube rush that could be heard from my listening position if I maxed out the gain on my preamp with nothing playing. So, I tried different things - changed/added grounding for the TT; changed the tubes in V1 and V2, and also V5; made the ground wires/connections a bit tighter; moved my SUT around relative to the TT and phono stage; used different shielded interconnects; created some flexible outside metal/copper shielding for the shielded interconnects from TT to SUT and from SUT to VTPH-2A, with the shielding then grounded to the ground posts. Each had a small but additive effect on S/N, eventually reducing noise by about -12dB to what the VTPH-2A is specified at (e.g., around -90dB). You should try some of the little incremental improvements that are out there because they can add up nicely and reduce noise. Noise is rarely just because of 1 piece of equipment or 1 issue.

Now, with max gain on my preamp, I can only hear a faint bit of tube rush if I place me ear right against the speakers. That’s what I would expect at -90dB. Otherwise, from my listening position, it is dead quiet. YMMV.

I have never heard an ARC phonoamp with "tube rush." They do have noise way down which is not a factor up to 110 dB in my system. I do use super low noise 6922's from Roger Modjeski's tubeaudiostore.com. He measures every single tube and puts them into three categories, standard, low noise and super low noise. The super low noise tubes are said to be one in 100 tubes tested. I have purchased 6 tubes and they are all obviously quieter than the ones ARC supplies. From my experience NOS tubes are a rip off. I had NOS Telefunken 6922s and they were no where close to Roger's tubes as far as noise is concerned. With Roger you know exactly what you are getting which is very reassuring. If your phono amp is noisy with super low noise tubes then it is either defective or a bad design. 

I have used super low noise new stock tubes from Kevin at Upscale. I got a 10-20% improvement in noise and a -25% penalty in sound quality from the NOS smooth plate Telefunken 12ax7s and the Brimar 13D5s that I prefer. Lots of tradeoffs in this hobby!

All tube phono stages do not have tube rush.  Sounds like a poorly designed unit IMO.  While it may sounds excellent as you say, there is something not right about the design.

@dhcod - the original Telefunken factory in CT is back in operation!

Happy Listening. 

@bigkidz

I have to disagree that the VTPH-2A is a poorly designed unit as it’s incredibly musical, especially at it’s price point. I really love what it has done for my vinyl experience. With that said I do wonder why Keith didn’t use the 6922/6DJ8 in his phonostage which is what he uses in his linestage. It seems noise would be much less of an issue because the EH 6922 is one of the quietest tubes there is for this purpose with ample gain.

@edwyun 

What tubes are you using in the V1, V2, and V5 positions?

FYI, When I had my VTPH-2a I noticed no difference in noise between the lowest noise new stock tubes and NOS telefunen 12ax7s and Mazda 12 AT7s. I had the version with the 2 12ax7s and 3 12AT7s. I loved this unit and compared it to a few others that were more expensive and it always won out. When I went with the Decca cartridge though, the Trumpet was doing all the same stuff but with some noticeably extra depth in the sound stage so I made a change. Keith Herron is the best. I still have his line stage and amps.

@ three_easy_payments

I agree. The VTPH-2A is a very highly regarded and designed unit. Even way above its price point. And very musical. There is unanimity on that.

As for tubes, I eventually found a set of 12AX7 EH tubes that tested and sounded better than the ones I had. It did make a difference. But then I found some NOS Ei tubes and they were even quieter.  I'm using the 12AX7 Ei in V1 and V1 and 12AT7 Ei in V5.

dhcod, It would take a severely defective tube to cause a 25% decrease in sound quality. I have not used a 12AX7 unit since 1965 and a Dyna PAS 3X but with 6922's the only significant difference between tubes is noise which is much easier to quantify than sound quality. Whatever differences there are in sound quality are marginal at best but having all kinds of crap going on in the background of quiet passages is annoying. I suppose if you only listen to Metal it does not make a difference and besides the tube with those gold pins must sound better. 

@three_easy_payments - I thought my post was very clear in that the phono stages mentioned may sound great but if the unit has noise then IMO something is not correct.  Why would I buy anything that had noise?  Like I said, these products may sound great but the designer did not take the time to design the unit to eliminate the noise so IMO that is a compromise in the design, maybe to make something at a price point possibly.  I don't use 6922/6DJ8 in my phono stage either.  The 12AX7 tubes work better in that application.  Happy Listening.

If you prefer tubes and have a low output moving coil it is best to use a solid state phono pre and employ tubes in the downstream electronics.  My recommendation would be to go with Nagra BPS.  It has high enough gain for low output MCs, runs off a 9 volt battery, is dead quiet and sounds fantastic.

dhcod, It would take a severely defective tube to cause a 25% decrease in sound quality. 

That would completely depend on what a person enjoys in their listening and their associated equipment. Maybe I was being a bit hyperbolic but I just wasn't enjoying the sound nearly as much.

Anyone here actually own a tube phono stage that is so quiet that when you place your ear right up against the speaker and the phono stage is active...and at some mild gain, but with no music playing ( or even at no gain) they hear absolutely no tube noise/rush ( dead silence)...I doubt it.

Again I agree with @daveyf , you can hear tube rush noise on any tube phono stage with just a slight bit of effort (or no effort, depending on the unit). It’s there. Yes the Herron VTPH-2A is very very low noise, one of the lowest I’ve heard - still there. And low noise tube selection is a must, but there’s no magical premium-platinum-plus selection that’s going to make it go away completely. It’s an issue of gain - a LOT of it is needed to amplify cartridge signals.

That said, for my ears, when you get to the low noise level of a VTPH-2A or my VAC phono, it’s low enough to not bother about, since groove noise will take over from there.

On the other hand, hum and buzz from grounding issues are positively insanity-inducing until resolved.

I've also had the experience that some NOS tubes can make for a substantial increase of enjoyment over new production, despite the increased difficultly of finding super low-noise examples. 

@daveyf and @mulveling
Agree 100%.  Can't avoid tube rush even with the best of tube phono stages.  It is very faintly there.  Whether you actually hear it will depend on how low output your MC cart is (and thus how much gain you need).

I have never heard an ARC phonoamp with "tube rush."

I think you will find that ARC uses semiconductors at the input of their circuits as well.

Even transistors have noise if you are placing your ear up against the speaker.

Happy Listening.

There's a fair bit of noise with my Herron. Its actually a bit noisier than the ARC PH3SE that I had for many years before that. Although in fairness I should say most of the noise I'm hearing is not due to the Herron per se, but the particular interaction with my arm cables and cartridge. In other words it could be reduced, and would be, if it was that big a deal to me.

Which its just not. Nor does it seem to be that big a deal to any of the many people who have been over to listen. Maybe link this thread to the other one as inordinate fuss over a little hiss definitely sounds like "What is wrong with audiophiles?" to me.

My rule of thumb is if you can't hear the hiss, rush, or even hum at the listening position with volume at a healthy level, then it's nothing to worry about.

Yes Ralph you are correct usually j fets I think and I do believe it is to reduce noise. My next phono amp Is going to be balanced. Can't wait to try that. I would like just a little more gain for ultra low output cartridges and I believe from what I have read that a balance design should have lower noise levels. Cartridges are balanced to begin with.

It's also possible that some phono amps "throttle down" gain with no signal present. That would give a false reading on the ear to speaker test.

noromance"It's also possible that some phono amps "throttle down" gain with no signal present"

That is ridiculous there is no such phono preamplifier in existence that is intended for Music Reproduction Systems.

I would like just a little more gain for ultra low output cartridges and I believe from what I have read that a balance design should have lower noise levels. Cartridges are balanced to begin with.

The reduced noise can be significant. For a given gain stage, if executed in the balanced domain you get a maximum of 6dB less noise. Now if you have two gain stages or more this adds up.

daveyf 11-11-2019
Anyone here actually own a tube phono stage that is so quiet that when you place your ear right up against the speaker and the phono stage is active...and at some mild gain, but with no music playing ( or even at no gain) they hear absolutely no tube noise/rush ( dead silence)...I doubt it.

I’m doubtful that is even theoretically possible with typical combinations of system gains, sensitivities, and volume control settings, even if a solid state phono stage is used.

Out of curiosity I did some quick calculations of the Johnson noise that would be produced by the resistance of my phono cartridge itself. As I mentioned earlier I use an AT-ART9, which is rated to produce 0.5 mv under the standard test conditions and has a specified resistance of 12 ohms.

I calculated that at room temperature and over a 20 kHz bandwidth the 12 ohm resistance would result in Johnson noise that is about 78 db below the cartridge’s rated output. If we assume for example that the volume control is set such that the cartridge’s rated output results in an SPL of 90 db at the listening position (which I think is a reasonable ballpark assumption), it would mean that the cartridge itself would be producing 12 db of noise at the listening position, within that 20 kHz bandwidth. That would almost certainly be inaudible at the listening position, of course, even when a record is not being played, due to the combination of RIAA equalization, A-weighting, ambient noise in the room, etc. But I would by no means assume that to be the case if the listener’s ear is placed up against the speaker, even if the phono stage, cabling, and the rest of the system add zero noise. My understanding is that an SPL of about 0 db is considered to be the nominal threshold of audibility, and 12 db at the listening position would correspond to a much higher volume right next to the speaker.

Regards,
-- Al

Whether or not you have "tube rush", in my opinion, is much more a function of the topology of the phono circuit than it is a matter of buying super low noise tubes. RAM and Kevin are completely reputable, but any tube will become noisier as it ages, and such aging can occur at different rates for different samples of the same tube type. So even SLN tubes are only SLN on the day they were measured. And one SLN may become only LN, for example, in a matter of several hours of use, while another may remain SLN for a much longer period.
I own both an Atma-sphere MP1 and a Manley Steelhead. The MP1 uses a dual differential cascode input voltage amplifier in the phono section, and the Steelhead uses a hybrid (solid state and tube) version of a cascode. (It’s single-ended.) Neither of these devices ever produces any tube rush at useable settings of the attenuator. The Steelhead, in fact, is silent for practical purposes (meaning you may hear a very faint noise at the sitting position if you are not playing an LP, with the volume control cranked all the way over).
It seems to me that phono stages deriving most of phono gain from the use of 12AX7 tubes at the input might be more likely to exhibit noise at high volume control settings.

Almarg, What formula did you use to calculate the Johnson noise of a phono cartridge? I was prompted by your earlier post to do some reading on it, too, and I would have guessed the noise of a phono cartridge per se would be much lower than what you quote. but I am not sure what are the correct values to plug into any of several equations I found on the internet.
Mijostyn, You can really achieve 110db SPL in your home audio system? I hope you don’t live in an apartment.

Almarg, What formula did you use to calculate the Johnson noise of a phono cartridge?

@lewm

Hi Lew,

I performed that calculation in two different ways, and got the same result both ways:

Method 1: The section of the Wikipedia writeup on Johnson noise that is sub-titled "Noise Voltage and Power" contains an equation for rms noise voltage which makes clear that rms noise voltage over a given bandwidth at a given temperature is proportional to the square root of the product of that bandwidth and the resistance which is responsible for the noise. That section also states as follows:

For a 1 kΩ resistor at room temperature and a 10 kHz bandwidth, the RMS noise voltage is 400 nV.[6]

Footnote 6 indicates that a more exact result is about 403.6 nanovolts, or 0.4036 uV (microvolts).

I then extrapolated from that number to the result corresponding to the 12 ohm resistance of my cartridge, over a 20 kHz bandwidth:

0.4036 x [square root [(12 ohms/1000 ohms) x (20 kHz/10 kHz)]] = 0.0625 uV

0.0625 uV is 78 db less than the 500 uV rating of my cartridge, since:

20 x log(0.0625/500) = -78 db

Method 2: I started with the following paper, although it pertains to microphone amplifiers:

https://www.sounddevices.com/microphone-preamp-noise/

The paper states that:

The noise generated by a 10k ohm resistor (based on the thermal noise formula above) is around 1.8 uV (-114 dBV).

I assumed they were referring to a 20 kHz bandwidth, or at least to something of that order of magnitude. I then extrapolated from the 1.8 uV/10K numbers to the 12 ohm resistance of my cartridge in a manner similar to Method 1 above, and after converting to db relative to the 500 uV rating of my cartridge I got the same 78 db result.

Best regards,
-- Al

Thanks. I can’t argue with your logic, and won’t.I might wonder whether one can model a phono cartridge based solely on its internal resistance, in that calculation.  But I have no better idea.

I might wonder whether one can model a phono cartridge based solely on its internal resistance, in that calculation.

@lewm, that’s a good point. But the inductance of my cartridge is spec’d as 25 uH at 1 kHz. If we assume its inductance is also around 25 uH at 20 kHz, its inductive reactance at 20 kHz would only be about 3 ohms. And it would be progressively less than that at lower frequencies, of course. So it would appear that the cartridge’s impedance is primarily resistive throughout the audible frequency range.

Best regards,
-- Al

@lewm - Sorry I wasn't more clear.  Yes, I meant thermal noise from input resistance. 

The SUT in question had 3900 ohms on the secondary (thin wire), which generated quite a bit of noise, much more than I get from my JFET-based headamp.

And yes, you can use the ESR of a cartridge to perform a baseline minimum noise floor calculation.  You then have added noise (aka noise factor in the RF world) from the amplification (which you can break down by stage).  The first stage is by far the most important.  That's why I use special low noise matched JFETs for MC front-end.

Another good test for "tube rush" is to compare noise level between open and shorted inputs.  Most of the noise you hear open is from the 47k loading resistor.  Shorted, you hear the amplifier and tube rush.  

if executed in the balanced domain you get a maximum of 6dB less noise

Actually, that's not true.  With balanced amplification you get 6dB more signal gain, but you also get 6dB more differential noise gain.  Overall SNR is the same.  

The benefit of balanced amplification is rejection of common mode noise such as power supply crud, and crap injected on both + and - inputs together (sometimes hum).  You get a better amplifier with higher overall performance, but noise floor from a differential source such as the resistance of a cartridge is the same.  

Lewm, according to the meter I have yes with peaks just slightly over 110 dB. (I had ear protection on at the time:) God knows how accurate the meter is. I think more remarkable is that this is with ESLs (using subwoofers from 125 Hz down). From 10 row center the last NIN concert I went to hit 120 dB (I also had hearing protection on) Getting the meter into the concert was a bit rough. Had to take the battery cover off and show that it was working while everyone behind was getting pissed. Anyway, the loudest I ever play it on rare occasions is 105 dB usually with concert videos. Most of my listening with Rock and Jazz is at 95 dB. Don't forget to warm up your ears first! 
I love your Steelhead, almost bought one but right now I am looking at Phono amps with balanced outputs and inputs. Coming from where Manley does you would think they would do that. 
We live in a house I have been building since 1993. 
In regard to the SLN tubes the only thing I can say is that with the system set at 95 db I can not here anything with my ear right against the speaker over the background noise of the house. With the volume maxed out I can just make out a hum, again ear against the speaker. The Tubes are now 6 years old. I have no idea if this is noisier than when they were new but even if they do get noisier with age I suspect a SLN tube will always be quieter than a LN or standard tube of the same age and make.

I then extrapolated from that number to the result corresponding to the 12 ohm resistance of my cartridge, over a 20 kHz bandwidth:

@almarg Most LOMC cartridges have bandwidth well past 20KHz- most have no worries going to 40KHz.

if executed in the balanced domain you get a maximum of 6dB less noise

Actually, that's not true. With balanced amplification you get 6dB more signal gain, but you also get 6dB more differential noise gain. Overall SNR is the same.  

IME you get the same gain- not 6dB more. We might have to straighten out our terms here- it might be that we are talking about the same thing.

Most LOMC cartridges have bandwidth well past 20KHz- most have no worries going to 40KHz.

Hi Ralph,

Yes, I realize that. But what I was attempting to calculate was an approximate figure of the amount of Johnson noise (aka thermal noise) attributable to the cartridge’s resistance **that might be audible** while a record is not being played.

@hagtech, thanks for confirming that the ESR (equivalent series resistance) of a cartridge can be used for purposes of that calculation.

Best,
-- Al

Almarg and Hagtech, Do I conclude from the talk about Johnson noise that (1) MM cartridges with their inherently much higher internal resistance and much much greater inductance will be noisier than MC types?  (But of course the noise that accompanies the greater gain needed for a typical MC vs an MM would swamp Johnson noise in most cases.)  And (2) what about all those high value Rs often used in an RIAA network, again, IF one is obsessive about Johnson noise?
I've never measured the R across the secondary of a typical SUT but I would never have imagined it could be as high as 3900 ohms.  Surprising.  I am not an SUT kind of guy, either.