Expanding questions about tubes in a preamp

I dont see how anyone could ascribe a commercial interest in this conversation. Actually the number of microphonic tubes one encounters is directly dependent on the number of tubes used over the years and also the sensitivity of the application. As sensitivity increases so does the percentage of microphonic tubes you will encounter. Put a fork in me....this is hopeless.

If you’re selling tubes you have a commercial stake in this nonsense so it’s no wonder you’re a bit testy (accidental pun) as helping people be worried about non-issues is clearly part of your business model...ethics be damned! If I don’t hear something it doesn’t matter to me. Period. I’ve owned piles of not so "pedestrian" (and you’re also a tube amp elitist? yeah man...insecurities galore dude) tube amps since the mid 60s, microphonic tubes are so rare as to be irrelevant, and if they display an audible bit of microphony they’re gone (in my career as a professional musician I can’t afford risking a bad tube)...I don’t need to test tubes as I can hear them, and that’s all the qualification I need.

Which post indicates insecurity? I have sold vacuum tubes on both a retail and wholesale basis for over 20 years so I think it fair to assume that I test more tubes in a day than you do in a year or perhaps over your entire life. Please tell me your vacuum tube qualifications other than using tube gear, albeit relatively pedestrian gear. You tend to believe that if you dont hear something that it doesnt exist. 

I'm absolutely right, but I do get that the insecure among us do get testy when somebody pokes holes in their silly paranoia driven tweaks...don't be sad "auddie"...again, dump audibly microphonic tubes...you won't regret it.

Dont listen to wolf he is dead wrong on this one.  

12AU7 mu 17 and requires a lot more input than 12AX7 mu 100.
Amplifier was designed for ????
Distortion in one case will be several multiples of the the other.
Perhaps the cymbal sparkle is odd harmonic?

... wanted more sparkle (cymbals) and discussed doing some tube swapping to 12au7s instead of 12ax7s... May try in the future.

Have always been experimenting with isolation, and swappng out interconnects: so I went in the closet, pulled out some old Harmonic Technologies interconnects - and POP! out came the cymbals, clearer more defined voice and PrAT I hoped for...

tomic601

...  ALL tubes to some degree ARE microphonic. Some less so than others- certainly a classic case is the 6922 vs 6DJ8. 

Huh? A 6922 is a 6DJ8. They're the same tube, just different nomenclature.

Like most topics here, some synthesis required...

yes ALL tubes to some degree ARE microphonic. Some less so than others- certainly a classic case is the 6922 vs 6DJ8.  The key is how much and what are the modes?

The various products vary of effectiveness as broad band dampers.

microphics you can’t hear can still consume power and inject noise in a wide bandwidth system and turn into artifacts you can hear.

Start with great tubes - @bdp24 gave you good advice - Roger Modjeski ( RAM ) built some great testing and grading equipment and knew how to use it. Andy at Vintage tube also knows his way around killer but let comprehensive and automated test equipment. He can be trusted :-)

Dampers can change the sound - you may not like it. You  should experiment :-)

Gents, how the hell does adding damping rings change the sound of a tube. Nonsense!

Answer: by reducing microphonics. The effect is easily measured and heard.

But using a low microphonics tube is more effective yet. Installing dampers on them has the most effect.

Hope I'm not putting words in @mulveling mouth--get a tube preamp that uses a better tube. I've never liked preamps with 12AX7s--the timbre seems off and dynamics seem non-linear. Hard to be sure, though, as it is the whole system being listened to, not just the tube type. In the preamp alone, there is the circuit, its parts quality, its layout, its build quality, and its output impedance match (or not) to the amplifier input. Add the source, amplifier, loudspeakers, cables, and the room and who knows? Even with something like the BHK preamp which uses either tube, there is still the possibility for optimization for one or the other.

geoffkait :
I enjoy your post very much and over the past couple of years have learned a lot from them.  But, you have a nasty demeanor.  Why is it acceptable to verbally assault others?

Skeptics say anecdotal, audiophiles say empirical. 

Hi,
wolf_garcia,
how do you explain same tube being microphonic on gain stage and not on the driver stage?  Same pre no tricks, no dampers used. Same quiet scenario in the more sensitive phono stage. It was a CCa 1962 pair brand new. Did i throw away the tube? No, used it, enjoyed it and after 2000hrs sold it to a new happy owner and the tube is running quiet and strong as new. Why i sold it? I am done with NOS tubes, just kept 60 of them after being struck with NOSphilia and having owned 552, a small fortune. That was an example and i have similar findings with other NOS tubes having  microphonic tendencies in the phono stage and being quiet in the line stage. Dampers do work in cases and it is not paranoia, but just a way to solve an issue. Just tossing a tube does not help.

ieales,
"A with tube damper testing is it is impossible to install / adjust them without moving the tube and refreshing contacts"
you can surely adjust the position of the damper on the glass if you use something that can roll on the glass while a tube is working (with gloves of course).
The way i put it is you may or not hear a differene but is far from anecdotal.
I agree with you that any chassis damping will have positive results for resonance control especially in areas like focus and bass quality.

Whatever is the most cutting. 🤗

Geoff, it's marone. Or were you calling him a deep red person?

What a maroon! 🐰 I guess audio school can’t fix your hearing. Tee hee

I've actually tried dampers and they provided zero improvement of the tonal aspects of any part of the performance of the tube amp and preamp, not unlike Kaitty's futile and irrelevant snarky posts. Microphonic tube paranoia is simply providing another tweak people can hang their hats on that has zero basis in sonic reality...if a tube seems microphonic, don't use it. Problem solved.

ieales
A with tube damper testing is it is impossible to install / adjust them without moving the tube and refreshing contacts.

Dampers could work by two methods: Vibration control and resonance damping. Assuming the envelope vibrates, what happens? The tube is a vacuum and sound does not travel in a vacuum. It could damp sound, which has very little energy, from travelling down the envelope to the base and up into the electrodes. One should be able to mathematically calculate the energy required to vibrate the electrodes. If resonance damping is the m.o. then where the damper is placed will affect its utility. Since all tubes vary slightly, how does one know if the location is correct for the particular tube. Model or item. AT, AU, AX, AY, BH // 66, 77, 88, 90, 120 150 for but two families.

It is quite trivial to set up a test wherein one records the output of a tube device w/wo dampers and delta the difference.

Since damper claims are anecdotal, I assume it’s never been proven.

>>>>>You sure make a lot of assumptions. When you ASSUME something you make a fool out of me and UMA Thurman.

ieales

Sound improved greatly adding the preamp in: better defined bass, voice
/ vocals more clear and moved "vertically up" in soundstage; veil over sound lifted slightly; soundstage expanded in width and depth with most instruments more clearly defined in the soundstage, rhythm and ’ toe-tappin ’ factor greatly enhanced...

Today’s Music: Dixie Chicks, Grateful Dead (especially Franklin’s Tower, on repeat), June Christy " Something Cool (both mono and stereo), Best of Blondie and Best of Van Morrison...

A  with tube damper testing is it is impossible to install / adjust them without moving the tube and refreshing contacts.

Dampers could work by two methods: Vibration control and resonance damping. Assuming the envelope vibrates, what happens? The tube is a vacuum and sound does not travel in a vacuum. It could damp sound, which has very little energy, from travelling down the envelope to the base and up into the electrodes. One should be able to mathematically calculate the energy required to vibrate the electrodes. If resonance damping is the m.o. then where the damper is placed will affect its utility. Since all tubes vary slightly, how does one know if the location is correct for the particular tube. Model or item. AT, AU,  AX, AY, BH // 66, 77, 88, 90, 120 150 for but two families.

It is quite trivial to set up a test wherein one records the output of a tube device w/wo dampers and delta the difference.

Since damper claims are anecdotal, I assume it's never been proven.

Hi,
looks silly or not if it works it's ok. If my memory is correct ARC did supply tube rings sometime with their gear. Virtually all tubes have the tendency to be microphonic (more the signal tubes) but it does not mean that they are bad ones. Most depends in their location on the circuit, a gain stage will expose it more and a driver stage less, so sometimes you do not even know it. Have you tested that all the tubes you are using are not microphonic and how? What sound do they make when you tap them?
Everything works, and my comment on a previous post that they sound more linear after using a tube damper is because microphonics/micro vibrations are somehow reduced. Last about hissing, we are talking about tubes which obviously have more hiss than ss.

Did you learn that in audio school, wolf boy? 😳

If a tube is microphonic simply replace it as dampers won't save it and are basically useless (and look silly)...note how many great tube amp designers don't bother with dampers...Shindo, Dennis Had, VTL, VAC, etc...they didn't get the memo? The myth that "all tubes are microphonic" is ridiculous and isolating everything is impossible and unnecessary...just listen to your amp and relax.

It has been argued to me that higher end audio component companies are making upfront decisions on the type and quality of the tubes in use.  So, if you have a high end product line, one should expect that the high end line is using the top quality tubes for their product and there shouldn't be a need to upgrade tubes - they were already upgraded in the first place.  Just let it ride.  I understand the desire to dink with sound and search for improvements.  We all do it.  

@insearchofprat:
Why change the EF86?
Unless the unit has been left on continuously for 10 years, the tube should have plenty of life.
Putting back 12AU7 will reduce gain about 6db.

Hum could be failing PS in the Wolze.

How is the Wolze interfaced to the HTA-5550?

Have you 'backed-up' from the power amplifier with shorting plugs to see where the noise originates. By that I mean put shorting plugs in the power amp and see what noise appears in the speakers. Then add the next upstream device with shorting plugs.

Just FYI, about 15 years ago when I added HT, every Yamaha model I tried, about 6, hummed. I designed and built recording studio wiring, so it was not user error. Denon, HK, Pioneer, Onkyo were all dead quiet.

Since the HTA-5550 does not need a pre-amp to accept signal from the SA-8001, is the Wolze simply a coloration effect?

Have you tried running theSA-8001 digitally into the HTA-5550?

Not certain if it’s OK to swap 12au7 for 12ax7 in the event your unit has been modified.

Maybe someone here knows.

My only familiarity with 86’s is from re-tubing a couple of vintage Vox guitar amps for a neighbor.

It seemed that he went through 86’s quite often as he had accumulated lots of duds.

I also recall 86’s with shiny/sparkling plates and others with normal dull plates, but don’t recall particular brands (other than the shiny Telefunken I had on hand).

Have you tried contacting the designer of the preamp?

Anyway, what type of noise are you experiencing (gently tapping on the unit will tell you if it’s microphonic)?

If this is it, then gently tapping on either/both tubes will tell you which one (or both).

DeKay

DeKay

Thanks for your clarification - probably the route I will go will be to
change to 12au7s

Can you suggest changing the EF86 to ?

Describe in detail what extraneous noise you are experiencing.

If it's "hiss" from the tweeters, then dampers are not the solution (cabling type and placement of the cables/gear would be as well as shielding unused inputs with shorted plugs).

I posted to your prior query and will add that your unusual preamplifier (which may be modified - due to it using a 12ax7 in place of a 12au7, which was standard in the original design) now uses two extremely high gain tubes (12ax7/EF86).

The original 12au7/EF86 design makes more sense (on paper anyway;-).

As far as micro-phonics go the 86 tube is notorious for such.

I'm wondering if the 12ax7 should be replaced with a 12au7 and if the 12ax7 was substituted in error @  one point and then remained.

DeKay

Gents, how the hell does adding damping rings change the sound of a tube.

Get two 6550’s one GE NOS green label and one Chinese junker, flick each and listen to the Chinese one ring like crystal and the GE just go thud. That’s the reason.
It’s all about airborne feed back from your speakers, if your tube pre and power amps were in another room there’d be far less concern.
This is why the flick test in my first post will give you a fighting chance against micro-phonics in tubes.


Cheers George

As others have shared, there are types of noise that are intrinsic to the component and the tube itself. As geoff points out all tubes have some degree of microphonics and the gain of the component in which the tubes are used has a huge effect on this phenomenon. Placement or isolation of a component also can have positive results. I agree with ieales that damping, isolation or relocation of the component are where you should start. Hiss is usually a component issue. I do not like dampeners for numerous reasons not least of which is mentioned by Ralph at Atmasphere. 

Hum is either a design or installation fault.
Hiss is a gain structure fault.
Microphonics are a tube fault.

IMO, chassis damping has more effect than tube dampers.

I first used VPI blocks on my Citation II in the late 70’s/early 80’s, whenever they became available. Blew me away. Been collecting more ever since.
Ditto support damping as seen here
http://www.ielogical.com/assets/M-125/VPIBrickDamping.jpg

NO ONE has ever failed to hear the difference!!

@OP - why such a cryptic topic?

... Phew! - this is getting more complicated - may have bitten off more than I can really manage at the moment...

Thanks to all for obviously educated and experienced info.

Gents, how the hell does adding damping rings change the sound of a tube. Nonsense! If your tubes are microphonic (ringing) adding dampers may quiet them down. If you have a noisy tube it won't help. But it also won't hurt. I have never heard anyone complain about, nor have I noticed, a change in sound due to the use of tube damping rings.

Using rubber bands as tube dampers? Sure, go ahead. As long as you don't mind smelling cooking rubber and the bands sticking to your expensive tubes, then cracking and falling off. Rubber bands are not designed to be heat treated.

Next silly suggestion: why not just coat your tubes with a healthy dollop of undercoating? It made my '67 Bug quieter.

I've had tube preamps that were too noisy for my system's downstream gain structure (both rush noise and microphonic feedback), and no amount of super special tube selection or tube dampers or HRS damper plates or expensive isolation stands did jack about it. Certainly, once you get "Platinum" selected tubes from Upscale Audio, there's not much (if any) improvement to be had from better selection. 

You have to pick a preamp with reasonable gain for your system and good signal to noise ratio. This is one measurement you can glean from Stereophile reviews that actually matters - for example, see the ARC Reference 6's 100dB signal/noise, which is excellent for a tube pre, and tests in my difficult system bear this out.

BTW if your line stage uses 12AX7 and EF86s, those are NOT typical choices for a modern tube line stage. 6SN7, 6922, 6H30 seem to be preferred (also in my experience). Though with the old 6SN7GT types, it is HARD to find quiet examples today.

Getting rid of microphonic tubes is far more important than damping rings. They have a tiny effect by comparison. I would only use them if you already have decent tubes.

Heat in tubes causes failure. The more damping rings and the like, the shorter the life.

if you buy into the tube damping thing, may as well go big
https://shop.mapleshadestore.com/Standard-Tube-Halo_p_1268.html

I use quiet  tubes, and I'm done with it. Careful, the more you learn, the more it increases unnecessary obsession. 

Herbies tube rings are the only way to go the others over damp the tube and you loose life and dynamics.

Uh, they’re all microphonic, even the ones that say ultra low microphonics. I used to get all my 12AX7s and other tubes from an insider who worked in maintenance at Goddard Space Flight Center, they were all WA military grade tubes. Sylvania, RCA, mostly. The only tube dampers that actually work and don’t hurt the sound are Herbies tube dampers. The rest of them you can throw in the trash. On 6SN7 tubes you should realize even better performance by using two, two dampers, one on the glass where the getter is located and another on the tube base. Yes, I know what you’re thinking, “but then I’d be spending more for dampers than I did for the tubes!”

Hi,
i would suggest to experiment with Herbies tube dampers, check them as there is variety of those, and not loose their grip or pressure on the glass over time. Silicon or rubber ones do work somehow are cheap but get loose or crack after some use due to heat. Whatever you choose will do in vibration control tame microphonis and make your tubes sound more linear if you want that. What i have found is that putting them on the upper part of the envelope, above top mica, is less affecting the tube character.

insearchofprat OP
Expanding questions about tubes in a preamp

First weed out any mircophonic tubes.
Do this by turning up the volume to where it sits normally for loud listening, get someone to gently flick each tube with his finger nail while you listen at the speakers for the bad ones. A quiet "bonk" is ok, loud or a tinkle behind the bonk (tinkle can be very loose stretched heater filaments) or sometimes when real bad you'll get run away feedback, quickly turn down the volume..

Once you have a batch of good non microphonic tubes in, then these cheap red "O" rings the thick ones, two per tube one high, one low not too tight. I have seen power tubes get a dent around them when they were too tight. (don’t bother with expensive audiofool tube dampers).
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313.TR5.TRC2.A0.H0.Xsilicone+%22o%22+rings.TRS0&_nkw=silicone+%22o%22+rings&_sacat=0&LH_TitleDesc=0&_osacat=0&_odkw=Red+silicone+%22o%22+rings

Cheers George

The RAM Tube Store meticulously measures all tube parameters, including noise. They then grade each tube, and offer matched pairs and quartets. They offer a Super Low Noise 12AX7's for use in phono amps, etc. A very quiet 12AX7 substitute is the 5751, which provides slightly lower output.

So just putting some rubber rings (O-Rings) picked up at a local hardware store would not be a good idea - or is it just again an experiment worth trying?

Better than paying for Herbies. I would try one per tube that fits snug (not real tight) and also a couple sized bigger. The big ones will let you shim or slide something between the o-ring and the tube. This will let you experiment with the vibration control effects of different materials- wood, paper, metal, whatever you want. I doubt you will find anything that does what you're looking for, but at least this keeps the learning costs down.

Using a tube damper will not quiet a noisy tube. Noise is usually inherent in the tube. Hum could mean the tube has a fault or it’s coming from elsewhere in the circuit.

Dampers can be used to reduce microphonics from a tube. They are often used to tighten up bass or reduce excessive overtones. And they will change the sound, so experimentation is necessary.

The only time I’ve used dampers is on a component with exposed tubes. Acoustic vibration from a speaker or vibration from the audio rack can be heard through some tubes.

... So just putting some rubber rings (O-Rings) picked up at a local hardware store would not be a good idea - or is it just again an experiment worth trying?

Good advice from Millercarbon.  I think you first need to decide if you like the sound you have.  If you do, just enjoy the sound and spend the money elsewhere.  Damping tubes can change the sound, but not necessarily for the better --try some inexpensive dampers and see for yourself if you must.  I have used various dampers, including Top Hats, Mapleshade (which can be overtightened and break the tubes, as I found out), Ensemble Kevlar sleeves and (the best) Andy Bouwman's octal tube dampers, and ultimately I found I liked the tubes without damping, I guess they sounded too dry and lost some bloom with the dampers, to my taste.

If you want dampers PM me I'll stick some in an envelope for you. The postage will be more than they're worth. Of course there are those who like them. There are also those who are happy to make money selling them to you. We have all kinds here.

My advice if you are curious is try some simple proof of concept tests that cost little or nothing to try. If tube damping is good you can damp a tube with a rubber band- cut some paper into strips wrap around the tube put a rubber band around it. Listen. Not something you want to leave on there very long but plenty long enough to listen and hear what it does. 

The expensive Herbies Tube Dampers I have are nothing more than a semi-circle of wire with a couple three bits of silicone that contact the tube. You could cut up some silicone made for kitchen use, its made to handle heat, try that. Point is you don't have to run around asking people, you can figure these things out for yourself and not even have to trust some stranger you never have and never will meet, who may even be so nuts he has his own website devoted to time travel and audio tweaks.