Easy/affordable way to test valves?

clarkefan

Is testing for "good" valves, or matching them, doable without expensive gear?

Over the years I've accumulated a couple of shoeboxes of old and more recent preamp and power valves, I'm interested in sorting them out.  Would be useful for spotting bad or weak new ones as well.

Happy to consider any ideas, thanks!

DJH83004

The Orange VT1000 would fit the bill, it tests most of the pre amp and power amp valves found in guitar amps (excluding rectifiers) and will match triode halves and output valves. They are expensive new, but have noticed they are starting to crop up secondhand. Alternatively take them to your guitar tech, who will probably charge a couple of pounds per valve to test.

57Deluxe

/\ last bloke I went to wouldn't - said it took him too long!

57Deluxe

hangon though - a slew of ideas on YTube...

https://www.youtube.com/results?search_query=home+made+tube+tester

DJH83004

You could always keep a look out for an emissions tester, which does all the basic tests, e.g heater integrity, grid shorts etc. And a good / bad measurement of electron emissions from the cathode. They will also test rectifiers, (generally they short the anode & grids together and test the Valve as a diode).
so if you are not looking for actual values of plate current and transconductance, they are a great go / no-go tester and simple to use.

ecc83

Clakefan, I have a chassis in my roof which is basically a 15W EL84 amplifier. I built it years ago and it could easily be modified so that you could plug in various valves and set bias and read electrode voltages. Next put a signal through them, drive the bits off 'em and give them a tap with a pen.

If they  survive all that and sound ok and the volts come out right they are pretty close to being right.

You can have the chassis if you come by but! IT IS NOT SAFE! All open to the pinkies so you need to know what you are doing around live kit.

Dave.

Wazmeister

Orange VT1000 - essential if you own any valve amps, imho

RiftAmps

I think the VT1000 is a bit of a rip off - it can only test a limited number of valves and the 'matching' number means squat in real-life terms.

You can pick up a good old built-like-a-tank emissions+shorts tester for much less, such as this Sencore - http://www.ebay.co.uk/itm/SENCORE-MIGHTY-MITE-TC-114-Valve-Tube-Tester-6L6-6V6-ECC83-12AX7-/302361104237?hash=item4666204f6d:g:hEAAAOSw3h1ZTv38

jpfamps

The problem with old valve testers is that that all hazardous to use as high voltages are exposed, and often in a poor state of repair, so I would not advise getting one unless you really know what you are doing. 

A significant proportion of the cost of the VT1000 was getting it through approvals for Worldwide sale. This is not a cheap process, and a cost that needs to be recovered.

The VT1000 certainly isn't perfect, but does subject the valves to a wider range of tests than most vintage valve testers.

The ultimate test though is in the equipment that the valve is going to be used, as few tester can test for microphonics or noise.

crunchman

I've got a couple of cheap little single ended 5W amps.  If you don't have a tester they can be handy for checking valves.  Just one preamp valve and one power valve.  Not a lot of use for matching though.

(Don't really need 2 though.  If anyone wants to buy a Champion 600 let me know.)

Gassage

The best way is to stand on them in bare feet.

If they're good they'll not break. If they're bad, they'll break and you'll hear that characteristic squealing noise.

jpfamps

crunchman said:

I've got a couple of cheap little single ended 5W amps.  If you don't have a tester they can be handy for checking valves.  Just one preamp valve and one power valve.  Not a lot of use for matching though.

(Don't really need 2 though.  If anyone wants to buy a Champion 600 let me know.)

That's actually not a bad way of doing it as you can listen to the valves.

clarkefan

Thanks all for your thoughts I thought a DMM could be used but apparently there's more to it than that

Thanks for the link to YouTube,  and fair point about old testers, I know enough to know I'm not savvy enough to be safe so will avoid.

Wonder if you can rent those Orange testers for a day?

DJH83004

I would still keep a look out for a second hand VT1000, they will test all common pre amp and output valves you are likely to come across in a guitar amp. The matching feature is useful, whilst it doesn't give any absolute valves of PC or TC,  it does 'score' the valves with a matching value, so you can pair / quad them up.

thermionic

I'm guessing that buying an old tester like that, it would only be as good as its calibration.