Premium Valve Testing
Are your output valves matched for use in your amp?
When buying matched power output valves, it is important to know at what voltages they were matched. Most valve suppliers put a sticker on the valve showing the anode current and the Gm.
But what were the test conditions?
So you might think they must be matched. Not necessarily the case. In the UK a number of suppliers use and maintian venerable testers such as the AVO Mk4. They are limited to a maximum test voltage of 400 volts. This is fine for EL84’s but what about the bigger valves that run at much higher voltages in amps?
If we take the example of the popular EL34 as used in Marshalls, Blackstar etc, the operating conditions can be 480 volts on the anode. The AVO test manual recommends testing at 250 volts.
They are run at 75% full power on an AVO. However, you want them matched in your amp so they really need to be tested at 480-500 volts and run at the typical 75% of full power. Otherwise, there is no guarantee they will be matched in the real operating conditions in your amp.
We reinforce this by providing a test certificate for matched power output valves showing the test conditions.
VTGA-200
Our power output valve tester can test at anode voltages up 640 volts and run the valves up to 100% power. We can also hear them to check for for microphonics and noise. This tester is a class A output stage complete with output transformer.
Here are our other testers :
Maxi-Matcher Tester
In early 2024 we introduced our Maxi-Matcher tester This bad boy tests not one, not two, but four output valves at once! Imagine the efficiency! It covers a wide range of valves, from the common octal base output valves to EL84s and 7189s. Basically, it’ll handle everything from a 6V6 up to a KT120. And being brand spanking new, it’s more reliable than our vintage AVO testers.. This tester is a back up to our VTGA-200..
Our Custom-Built VTGA-100 Pre-Amp Valve Tester with audio check
Ah, the ECC83/12AX7, the rockstar of valves!
We launched this tester in February 2024. and it can handle up to 16 of these beauties simultaneously. It’s a whopping three feet long (or just under a meter), weighs 20Kg (44lbs in old money), and tests each tube in a circuit typical of the V1 position in your amp. Plus, it can check most pre-amp valve types and can even select balanced valves for the phase splitter position.
And there is more!
With this new gear, we can also listen to each valve to check for microphonics, noise, and hum. And even hook up an oscilloscope to look at the noise spectrum for detailed analysis.
The picture below shows 8 ECC83/12AX7 preamp valves being tested.
We teamed up with Chris at Vintage Amp Services to craft this beauty. Chris did an incredible job constructing the unit to our specifications, and put a ton of his own expertise into details of the design. And hey, if you’re in Swindon and need an amp repaired, give him a shout! He’s a veritable expert with vintage valve amps.
Element Engineering and Design Limited in Wiltshire, UK, used an NC machine to tool the strong steel chassis of this tube testing monster.
And as for those old AVO testers? Just hold your horses! We’re not bidding farewell to those faithful friends just yet. They’re still on duty, handling ‘oddball’ valves and rectifiers. We’ve just beefed up our testing game for the more common valves.
Our AVO Testers
We have two AVO testers . Our Mk 3 is now dedicated to testing rectifiers . Yes we test every tube rectifier before shipment.
Out AVO CT160 tester is used to test the much less common valves such as the EH 6973 and Ting Sol 7591 Ok so we cannot listen to these as yet but we are working on it .
