There are many types of add-on sockets with leads for the current meter. Use or buy your own DVM,
and that will be much better than a cheap meter box included with a socket.
TubeDepot.com | TubeDepot Bias Scout Kit
Amazon.com: Eurotubes Bias Probe for Octal Base Power Tubes.: Musical Instruments
and that will be much better than a cheap meter box included with a socket.
TubeDepot.com | TubeDepot Bias Scout Kit
Amazon.com: Eurotubes Bias Probe for Octal Base Power Tubes.: Musical Instruments
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For some popular tubes,take a look at the Orange Tube Tester.Though it looks like a toy and implicit limitations,it does a great job for what it is.Compared it with a TV-7 and it's spot on.
Valve Tester – Orange Amps
Valve Tester – Orange Amps
Not all valve/tube testers test a true load but those that do apply a signal to the grid and impose a current load and voltage to the plate appropriate to the valve/tube that is a continuous load not a constantly variable one you get with a music signal .
What you seem to be asking for is not an emission/GM tester but a "performance tester " that is directly connected to the tube (tubes ) WITHOUT it affecting the normal performance of the amplifier in ANY way .
There is industrial equipment ( or was ) that tested in this way but it cost a fortune .
Rayma is right check the tube current when playing music and judge for yourself just remember its continuously variable on a music signal .
And remember you are also checking other variables so the tube is not being tested under scientific conditions relevant to the tube -IE -- in isolation .
Even testing with a fixed tone still doesn't impart the true state of the tube while its still part of the amplifier that's why high end mutual conductance testers have many controls to vary the conditions under different fixed signals and loads .
If anybody knows of a commercial high end tester that tests the tube ACCURATELY while still installed as part of your favorite amplifier please let me know ?
If what you want was an acceptable practice in industry every tube/valve equivalent book would need to be re-written.
What you seem to be asking for is not an emission/GM tester but a "performance tester " that is directly connected to the tube (tubes ) WITHOUT it affecting the normal performance of the amplifier in ANY way .
There is industrial equipment ( or was ) that tested in this way but it cost a fortune .
Rayma is right check the tube current when playing music and judge for yourself just remember its continuously variable on a music signal .
And remember you are also checking other variables so the tube is not being tested under scientific conditions relevant to the tube -IE -- in isolation .
Even testing with a fixed tone still doesn't impart the true state of the tube while its still part of the amplifier that's why high end mutual conductance testers have many controls to vary the conditions under different fixed signals and loads .
If anybody knows of a commercial high end tester that tests the tube ACCURATELY while still installed as part of your favorite amplifier please let me know ?
If what you want was an acceptable practice in industry every tube/valve equivalent book would need to be re-written.
duncan2,
What Eurotubes.com (in the US) does is re-test all the JJ tubes that they sell.
I know their designer, and also another designer who I worked with in a Test and Measurement company.
They create special test equipment, nothing like a classical tube tester.
I know that they test the tubes at, or near to, some data sheet operating conditions,
voltage, current, bias, transconductance, etc.
They also test for noise, microphonics, and who knows what else.
I believe they will test at your specific voltage, current, and bias if you request.
But I would not expect them to test them at higher than the specified maximum levels.
It is not fair to other customers to Abuse several tubes in order to find matched ones, and then to sell the rest to unsuspecting customers.
I always purchase matched tubes, even for single ended mono-blocks. But even when I use them in push pull amps, the match is superb (I use individual self bias when I can; but self inverting output stages have the cathodes tied tougher, and the match is good here too).
Whenever I can find the tube type I want, and it is a type that is manufactured by JJ,
I always purchase them from Eurotubes.com.
Sometimes I have them shipped to me, and sometimes I just drive over and pick them up.
They are in the greater Portland Oregon area.
I think they sell to a number of overseas countries.
They are known by both Electric Guitar and Hi Fi people alike.
What Eurotubes.com (in the US) does is re-test all the JJ tubes that they sell.
I know their designer, and also another designer who I worked with in a Test and Measurement company.
They create special test equipment, nothing like a classical tube tester.
I know that they test the tubes at, or near to, some data sheet operating conditions,
voltage, current, bias, transconductance, etc.
They also test for noise, microphonics, and who knows what else.
I believe they will test at your specific voltage, current, and bias if you request.
But I would not expect them to test them at higher than the specified maximum levels.
It is not fair to other customers to Abuse several tubes in order to find matched ones, and then to sell the rest to unsuspecting customers.
I always purchase matched tubes, even for single ended mono-blocks. But even when I use them in push pull amps, the match is superb (I use individual self bias when I can; but self inverting output stages have the cathodes tied tougher, and the match is good here too).
Whenever I can find the tube type I want, and it is a type that is manufactured by JJ,
I always purchase them from Eurotubes.com.
Sometimes I have them shipped to me, and sometimes I just drive over and pick them up.
They are in the greater Portland Oregon area.
I think they sell to a number of overseas countries.
They are known by both Electric Guitar and Hi Fi people alike.
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Measuring cathode current is easy : install a resistor 1ohm between cathode and ground, voltage across resistor in mV equals current in mA
( as screen current is added the cathode current will be somewhat higher, the
data sheet for the tube will give an approximation of plate / screen current. If
no other info is present assume 5% of current is screen)
If amp is under load, then the AC voltage across the resistor is measured,
best with an oscilloscope.
Very true. If one has one of these a serial resistor of an ohm and a proper
oscilloscope set up for differential will do the job.
I use 3 current-metered supplies and a test bed to connect them to tubes. One supply is for plate current, another for screen current, where applicable, and the last one is a grid bias/control supply, connected to supply negative voltages. With a copy of the published specs for the tube DUT, I can see if a tube will work in its intended application using this setup.
This is what I found but it is for octal tubes only.
Bias King Bias and Matching Twin Meter For Sale
Bias King Bias and Matching Twin Meter For Sale
6A3sUMMER - JJ use an Amplitrex AT 1000 tube tester , yes its digital/computer controlled but you still plug the tube into the tester not an amplifier as the OP asks about .
Yes it does a lot of things automatically but I can measure noise /insulation/gas test/ plate to 100ma /GM etc on my old AVO .
I am not saying its not sophisticated and modern but several websites have criticized it including -
We had problems with the AMPLITREX AT 1000 tube tester.
Somewhere I have the circuit for a digital tube tester , I cant remember if its from EW or elsewhere I will try and find it .
Yes it does a lot of things automatically but I can measure noise /insulation/gas test/ plate to 100ma /GM etc on my old AVO .
I am not saying its not sophisticated and modern but several websites have criticized it including -
We had problems with the AMPLITREX AT 1000 tube tester.
Somewhere I have the circuit for a digital tube tester , I cant remember if its from EW or elsewhere I will try and find it .
duncan2,
The Ampiltrex was only the beginning at Eurotubes.
No one piece of test equipment does it all, and no piece of test equipment is perfect.
There are many other kinds of test fixtures at Eurotubes.
One is another specialized tube tester.
One tests at extremely high voltage and current
One tests noise
Etc.
Every time I go there, there is more testing.
And after anyone gets tubes from Eurotubes (or anywhere else for that matter), the best test equipment in the world is the amplifier that they are installed in.
The exact voltages, currents, bias, drive impedance, load including all reactances, local negative feedback (if any), global negative feedback (if any), the complete amplifier power supply, and whatever else is particular about a circuit, topology, etc.
In my amplifiers:
I have had current sense resistors in the cathodes, control grids, screens, and plates, depending on the circuit, the tube, the particular need, etc.
One time, I put a 15 Ohm resistor in one plate lead, to equalize the 15 Ohm DCR difference of the Push and Pull plate leads of the output primary. That allowed easy measurement to check the current balance adjustment - just turn the pot until the DC voltage from plate to plate was zero.
Testing is only as good as how creative the test is.
The Ampiltrex was only the beginning at Eurotubes.
No one piece of test equipment does it all, and no piece of test equipment is perfect.
There are many other kinds of test fixtures at Eurotubes.
One is another specialized tube tester.
One tests at extremely high voltage and current
One tests noise
Etc.
Every time I go there, there is more testing.
And after anyone gets tubes from Eurotubes (or anywhere else for that matter), the best test equipment in the world is the amplifier that they are installed in.
The exact voltages, currents, bias, drive impedance, load including all reactances, local negative feedback (if any), global negative feedback (if any), the complete amplifier power supply, and whatever else is particular about a circuit, topology, etc.
In my amplifiers:
I have had current sense resistors in the cathodes, control grids, screens, and plates, depending on the circuit, the tube, the particular need, etc.
One time, I put a 15 Ohm resistor in one plate lead, to equalize the 15 Ohm DCR difference of the Push and Pull plate leads of the output primary. That allowed easy measurement to check the current balance adjustment - just turn the pot until the DC voltage from plate to plate was zero.
Testing is only as good as how creative the test is.
My L3-3 tester does that. But as has been said before: you can test them in the amplifier. Hook up a signal generator to the input and measure.
As for testers: for matching (if that is necessary is a discussion or several on their own...) using a conventional tube tester is useless as they give you a single reading at an operating point that might with a lot of luck be the same as in your amplifier.
Since I have built an eTracer all my other testers have gone on eBay or the shelf. Before the eTracer my method of testing tubes for matching them was a bunch of adjustable power supplies (set to replicate the intended operating conditions) and a meter.
As for testers: for matching (if that is necessary is a discussion or several on their own...) using a conventional tube tester is useless as they give you a single reading at an operating point that might with a lot of luck be the same as in your amplifier.
Since I have built an eTracer all my other testers have gone on eBay or the shelf. Before the eTracer my method of testing tubes for matching them was a bunch of adjustable power supplies (set to replicate the intended operating conditions) and a meter.
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The L3-3 tube tester is a card operating machine not a fully adjustable manual tester .
I had the AVO equivalent but it meant buying new cards continually due to tube innovation.
It also wouldn't do exotic tubes .
In answer to tube matching my MK4 AVO VCM can be modified for tube curve tracing but a graph can be built up at various grid/plate values just by using the adjustable controls , yes it takes a while as its manual but you get there in the end .-
AVO K4 IV Tube Valve Tester. Page with panel meter information.
I have completely refurbished it with the original meter being in place and working well when I bought it its ex UK government weather station and war dept used.
R36 is now of a value of =0.1 %.
I had the AVO equivalent but it meant buying new cards continually due to tube innovation.
It also wouldn't do exotic tubes .
In answer to tube matching my MK4 AVO VCM can be modified for tube curve tracing but a graph can be built up at various grid/plate values just by using the adjustable controls , yes it takes a while as its manual but you get there in the end .-
AVO K4 IV Tube Valve Tester. Page with panel meter information.
I have completely refurbished it with the original meter being in place and working well when I bought it its ex UK government weather station and war dept used.
R36 is now of a value of =0.1 %.
Why are Eurotubes.com spammed and promoted in almost every tube thread?
6A3Summer, you must have a boat load of shares!
I mean, perhaps it's relevant advertising for those in NA... but for those in EU and the other 7/8ths of the world, there are plenty of UK and EU alternatives for sourcing valves.
6A3Summer, you must have a boat load of shares!
I mean, perhaps it's relevant advertising for those in NA... but for those in EU and the other 7/8ths of the world, there are plenty of UK and EU alternatives for sourcing valves.
Eurotubes seems to test and deliver it's goods with warranty. Not so very common these days. ( and i have no affiliation )
mondogenerator,
So many posters in Tubes / Valves badmouth JJ tubes.
And they do that very often.
JJ quality has increased dramatically over the decades.
I do not have any shares, free tubes, or any other such bribes from Eurotubes.com.
Eurotubes takes the shipment of tubes they get from JJ, and does extensive re-testing.
But if anyone badmouths a company that I know well, and that I deal with regularly, and that is wrongly accused, I will defend them.
Badmouth often.
Then I will defend often.
Is that wrong?
Source your favorite brands, and favorite dealers as you wish, of course.
Keep all purchases local if you wish.
Eurotubes.com sells outside of the US.
I purchase various products from China, Russia, Europe, etc.
I am not afraid to pay for shipping, and to pay for customs if any.
You can do the same if you wish.
What is wrong with that?
And . . . I do purchase NOS tubes when I need a particular tube type that is not available in current production, JJ or other brands current production too.
I do not exclusively use JJ tubes.
So many posters in Tubes / Valves badmouth JJ tubes.
And they do that very often.
JJ quality has increased dramatically over the decades.
I do not have any shares, free tubes, or any other such bribes from Eurotubes.com.
Eurotubes takes the shipment of tubes they get from JJ, and does extensive re-testing.
But if anyone badmouths a company that I know well, and that I deal with regularly, and that is wrongly accused, I will defend them.
Badmouth often.
Then I will defend often.
Is that wrong?
Source your favorite brands, and favorite dealers as you wish, of course.
Keep all purchases local if you wish.
Eurotubes.com sells outside of the US.
I purchase various products from China, Russia, Europe, etc.
I am not afraid to pay for shipping, and to pay for customs if any.
You can do the same if you wish.
What is wrong with that?
And . . . I do purchase NOS tubes when I need a particular tube type that is not available in current production, JJ or other brands current production too.
I do not exclusively use JJ tubes.
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Mondogenerator , if its any consolation after the annihilation of the British valve industry and outsourcing to all parts , usually east (far ) you can only blame government policy (profit ) .
This applies to the USA too but the USA is now back to its starting its own manufacturing base which personally I approve of.
Likewise Brimar -UK under new British control has got funded to reestablish a British manufacturing base .
This is still in progress and staff are advertised for but I wholeheartedly approve of ANY country taking back its long gone manufacturing and as an ex. engineer I still remember what it was like back in the old days when you were tripping over all types of engineering factories from mechanical to electrical/electronic .
If you have to "blame " anybody blame the politicians not the general public of any country.
This applies to the USA too but the USA is now back to its starting its own manufacturing base which personally I approve of.
Likewise Brimar -UK under new British control has got funded to reestablish a British manufacturing base .
This is still in progress and staff are advertised for but I wholeheartedly approve of ANY country taking back its long gone manufacturing and as an ex. engineer I still remember what it was like back in the old days when you were tripping over all types of engineering factories from mechanical to electrical/electronic .
If you have to "blame " anybody blame the politicians not the general public of any country.
FWIW and just commenting : I don´t make many tube amps; only, say, 10 a year or so (compared to 200-300 SS ones in the same period) and have mixed feelings about JJ
Up to some 10 years ago I was sometimes burnt by inconsistent quality, say I had to buy 6 EL34 to get 4 perfect ones (so I knew they CAN make good stuff), 1 acceptable although somewhat outside of what´s expected and 1 "why did they ship his?"
Mind you, that on power tubes; no problems with 12AX7 .
But now they provide consistent quality.
In the old days, sometimes I asked Customers to buy tubes themselves, worst case I did not get stuck with "dogs" which I would have to replace out of my pocket.
Consider tubes here cost about twice the International market price so a bad one hurts and warranty simply does not apply.
Sometimes when I had to buy them myself I resorted to "Guitar Amp branded" ones, say "Fender" , "Marshall" or even Sovtek tubes, knowing that although they can only come from the few remaining manufacturers, at least they are "pre-sorted" by them, no shining stars but no dogs either.
Up to some 10 years ago I was sometimes burnt by inconsistent quality, say I had to buy 6 EL34 to get 4 perfect ones (so I knew they CAN make good stuff), 1 acceptable although somewhat outside of what´s expected and 1 "why did they ship his?"
Mind you, that on power tubes; no problems with 12AX7 .
But now they provide consistent quality.
In the old days, sometimes I asked Customers to buy tubes themselves, worst case I did not get stuck with "dogs" which I would have to replace out of my pocket.
Consider tubes here cost about twice the International market price so a bad one hurts and warranty simply does not apply.
Sometimes when I had to buy them myself I resorted to "Guitar Amp branded" ones, say "Fender" , "Marshall" or even Sovtek tubes, knowing that although they can only come from the few remaining manufacturers, at least they are "pre-sorted" by them, no shining stars but no dogs either.
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