Valve etiquette and care

King_Julian_S

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Hi all...
As Topic suggests...

I noticed a comment made by Charles on a thread I read earlier...
So I was thinking maybe a good idea is to start this seperate thread.
The idea is for the masters to share some knowledge with novices like myself in terms of simple tips and tricks to enable us to learn how to care for our beloved valve equipment and perhaps not even make silly mistakes that could make one regret the things you wish you knew...Matbe even general Maintenance and care tips if there are.

Tx in advance.

So to start it I will steal Charles's tip as the first one. Cause I know I've done this before and thanks goodness I was lucky that mine survived.

TIP...1

"Always connect speakers to valve amps before powering them up as some of them could go "bang" if you don't."

 

Winslow

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Yep. Transformer sees speakers as a load no load puff go transformer happens in a flash.
not all amps are like this but it is a good idea just to be sure.

Turn amp on last turn amp off first.

Don't move or bump when it is hot or on valves delicate when glowing.

Pull valves out at the base

Don't poke around in there if you are not an expert the voltages inside will kill you one time.

Give it at least 30+ seconds before playing give the valves a chance to warm up gives them an easier life and they last longer.  The more modern amps have a slow start feature.

And Myself I run fans on them when not doing critical listening easy enough to turn off if the noise bothers me extends the valves lives in a big way.  Some of them are pricey critters.

I always wear cotton gloves when handling the valves but some say it is not required.
 

croak

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Don't use your amp as a valve tester for that stash of untested NOS you found on the dump. Confirm all good first.

Unlike solid state amplifiers, adding speakers and putting them in series is not safe.

 

King_Julian_S

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Shoo tx guys
I can confirm that I have contravened all of the above...

Just a quest ...
My amp switches off at the mains...
There is a switch on the amps self that apparently cuts the inputs off , so I would normally turn volume off , flick those switches and then off the other equipment and then the wall... So , am I switching it off in the wrong sequence then ? Maybe I should put the amps on their own plug and switch off there first ?

I should also stop fiddling with valves when the amp is on , I find I have this habit to switch on , let it heat up long and then decide I have to ensure they are in their holes properly for some reason and tap on them..
I will have to stop doing that... Tx
 

Winslow

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King_Julian_S said:
I should also stop fiddling with valves when the amp is on , I find I have this habit to switch on , let it heat up long and then decide I have to ensure they are in their holes properly for some reason and tap on them..
I will have to stop doing that... Tx

Remember the old lead lights always having to replace bulbs they did not last long at all.
All the moving around and banging did the filaments in quick. The Filaments are very weak when glowing only reason they don't burn out is because of the vacuum inside same with valves or vacuum tubes

King_Julian_S said:
Just a quest ...
My amp switches off at the mains...
There is a switch on the amps self that apparently cuts the inputs off , so I would normally turn volume off , flick those switches and then off the other equipment and then the wall... So , am I switching it off in the wrong sequence then ? Maybe I should put the amps on their own plug and switch off there first ?

I would do that make up a nice box with outlets for the amps alone and put individual switches on each line if you are running Mono Blocks.
Some nice Shielded cable to the amps.

Here is another hint I run shielded power cable on all my equipment and only earth the shield on the source side on everything.

Also my interconnects use balanced two core cable shielded, one core feed one core return shield only earthed on source side. I do not use the shield as return.
The systems are dead quite and I mean silent as death not a rush or a hum to be heard.
The only thing you can hear is a ever so slight rush with the volume turned right up max with your ear glued on the tweeter from the phono input. That is par for the course.
Playing volumes  not a thing.
 

King_Julian_S

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Mr W
Any ideas on where to source such cables ?
I use a normal kettle type plug , but I also get dead quiet response when volume is all out... And the speakers are very high sensitivity drivers as well.

I do get a very slight " Doooof " sound when I flick those switches I mention above to the on position...


 

Phase

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Nice thread King_ I'm getting into valves for the 1st time now and as a newbie I knew none of the above...
 

Phase

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Please keep the tips coming... and maybe some on the maintenance side...
Thanks in advance  :thinking:
 

Ampdog

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All is not that glum.

The heaters in valves are actually quite shock-proof as they are sturdily 'packed' inside a cathode (the glowing tube seen - not talking about the old directly-heated stuff still used in some S.E.T.s). Do remember that WW2 was won with valve equipment ....

The envelopes are normal glass; no need for special gloves. It is well though to keep too many fatty sticky fingerprints off; they 'burn in' and look ugly (power valve glass temperatures can reach 270o).

No decent valve amplifier should go unstable with no load (there is/should-be a built-in load resistor) .... but yes, not all valve ampliifers are that decent. (...and there are at least an equal number of semi-conductor ones also not liking that!). Short the output of some SS amplifiers even for a fraction of a second and they are gone - not so with valve amplifiers.

I am unsure as to why switching on/off should be done in a certain order of things or without signal; not to my experience - enlighten please? (Again, they are actually more rugged in that sense than many SS ones. The 'road-to-fully-on' is actually more quasi-unstable with many transistor amps, what with the high degree of NFB often employed.)

Heat: One might keep in mind that maximum valve dissipation values (EL34: 25W;  6L6GC: 30W;  KT88: 35W etc.) refer to 25oC ambient (as it does for most electronic components). The greater danger is to the components warmed by valves in the vicinity, like electrolytic capacitors. And then keeping the glass clean also assists in cooling. A valve covered in muck cannot radiate as well as a clean one. In fact, a good idea to keep all electronic stuff clean - and also occasionally blow out the dust inside your PC monitor! (being switched off, of course ...) A layer of sticky dust inside a 20 year old valve amplifier begins to provide other paths for the electrons.

How does one clean a really filthy amplifier? You take out the valves, and dunk it into a bath with hot water and some Sunlite liquid or Mr Muscle (not oven cleaner), and scrubb with a brush!! Then wash/rinse all off thoroughly, and let it dry, even more thoroughly!! - before going back to operation. (This is time consuming, also watch out for moisture in unpotted transformers and such - might have to take the covers off or so - blow,  :blah:.)

Valves are sensitive to heater over-voltages. It would seem that some models from the east do not have their transformers correctly aligned. I have measured 6,9V heater voltage instead of the usual 6,3V. If mains tappings do not allow the right adjustment, the only way out is the rather inelegant way of adding low-value resistors in the heater circuits. It might also be done in the primary. Sadly that influences the power supply 'stiffness' slightly - not too important in valve amplifiers. But heater over-voltage (I mean substantially) drastically shortens valve life, particularly power valves.
 

Andre Vermeulen

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Ampdog....interesting to read re heater voltages.....currently have an amp that shows 5.8 volts for the 6.3volt heaters.....what would be the problems as a result of this?Thank you.
 

croak

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King_Julian_S said:
Mr W
Any ideas on where to source such cables ?
I use a normal kettle type plug , but I also get dead quiet response when volume is all out... And the speakers are very high sensitivity drivers as well.

I do get a very slight " Doooof " sound when I flick those switches I mention above to the on position...

I keep the lowveld audio screened mains cables and recommended gold props and Schurter IECs.
 

croak

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The reason for the switch on and switch of sequence is to never unnecessarily amplify any switch on thumps from gear further up the chain.

IMO as long as the power amps are switched on last and switched off first the others don't really matter.
 

Winslow

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I quote from Line Magnetic 211IA owners manual.

1: Forbidden to operate as unloaded.
2: Forbidden to operate when the output is open or shorted.

I quote from Opera Audio Cyber 800 Mono Block owners manual.

1: Source components and power supplies should be switched on before switching on amplifiers.
2:Always switch the amplifiers off and wait 5 minutes for its power supply capacitors to discharge before connecting or disconnecting any leads.
3: Always use the power switch on the product rather than the mains outlet switch.
4: With the preamplifier volume turned down to zero turn preamplifier on first then turn on power amplifier. This will minimize the chance of damage to the speakers.
5: Note: Never turn on the amplifier unless there are speakers connected to both out put terminals. Operation of the amplifier without a load can damage the output transformers.
6: Note it takes about 1 minute for the EL34 to reach its operating point.

It also gives the same turning on and off sequence in my Audio Research Valve Preamp manual.  These guys know their oats I would presume.

These are all more than decent Amplifiers by a big margin so will obey the guys who made the things.

How many of us have manuals or understand the design of our second hand valve amps these are precautions that are easy to follow why not don't take a chance not worth it.

I have fried a Solid State Mono Block of a very good make by swapping around interconnects amp was off.
Pre was still on with volume up nice pretty blue flash and bang amp cooked nice one.
On having it repaired the tech a well respected fellow said to me never do that turn the volume down always when fiddling around if you are so silly as not to turn it all off first.

Second story fried the power supply on a top class preamp by turning it off and on at the wall and not bothering to turn it off at its power switch.
Well respected Tech the dear departed Gunter Greef asked me what I was doing dold him he just shook his head "don't do that".

As for operating without a load know a fellow who fried his output transformer by switching on with out a load.

So from experience these hints are passed on cant be to careful the stuff is expensive to fix so why take a chance.

King_Julian_S said:
Mr W
Any ideas on where to source such cables ?
I use a normal kettle type plug , but I also get dead quiet response when volume is all out... And the speakers are very high sensitivity drivers as well.

I do get a very slight " Doooof " sound when I flick those switches I mention above to the on position...

You can also try the good fellow Ian (Aka Jim Gore) for power cable 083-4924148.
Not cheap but not silly like prices same as Hi-Phibian's always reasonable prices with excellent service to boot.
No silly things like a rhodium plated ICE plug for R1,500 ea.
I find the sonic advantages worth it.  Cables do work  :tongue:
The Doof with sensitive speakers is annoying don't know what to do about that have the same problem when turning off some stuff.  Always turn volume down and mute before turning off components and power supplies.  Guess we have to live with it unless we install dedicated individual power lines.

Another annoying thing about sensitive speakers is the volume control either too loud or too soft hard to get it just right.
But as those are the only negatives and they sound so good will live with it.

 
 

charles

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"How does one clean a really filthy amplifier? You take out the valves, and dunk it into a bath with hot water and some Sunlite liquid or Mr Muscle (not oven cleaner), and scrubb with a brush!! Then wash/rinse all off thoroughly, and let it dry, even more thoroughly!! - before going back to operation. (This is time consuming, also watch out for moisture in unpotted transformers and such - might have to take the covers off or so - blow,"

I will not do it with all valve amplifiers as some have open OTF's and MTF's and when the water seep into the TF then it will be ruined, specially when it has paper insulation. Handle your transformers with utmost care.

There are lots of "ghost stories"around regarding the handling of valve equipment such as "right" procedure to turn it on or off. I do not believe in most of it.

I have fixed and restored probably hundreds of old and new valve amplifiers in my time. True there are the basic principles when working with valve equipment, but if I have to go by some of the extensive do and dont's in this posting it will take me a helluva lot of time to restore/fix a simple valve amplifier.  Or even to listen to a valve amplifier.

 

King_Julian_S

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Tx all
Some major contributions here.
I suppose like most things you take in what u think is relevant.
But again I must say thank you and thank you again for all the selfless info.

Pls keep it coming 👌.

Eish , since my cleaning endeavors with my Alphason , I have vowed to only ever do dry cleaning from here on 😄
 
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