Testing & Matching
We pride ourselves on our rigorous testing & matching standards.
All new production tubes are tested on modern equipment which simulate real-world conditions with all vintage tubes are tested on calibrated vintage equipment. We do this because tube specs have changed over the 100+ years they have been around. Modern tubes will sometimes not test properly on vintage equipment and vice-versa. Please do not trust your 50 year old emissions tube tester to give an accurate reading on a modern tube for appropriate Ip / Mu parameters.
Preamp tube testing
Our preamp tubes are tested using power-regulated Maxi-Preamp testers for Mu (gain) and Gm (general mutual transconductance) at proper operating voltages. Preamp tubes are also screened for all other appropriate parameters such as shorts.
* Preamp tube balancing: If you require a balanced tube, or a specific balanced tube within a matched set, please leave an order note/comment when submitting the order explicitly stating your request.
Power tube testing
Our power tubes are tested using power-regulated Maxi-Matcher power tube testers for Ip (plate current) and Gm (general mutual transconductance) at proper operating voltages. Power tubes are also screened for all other parameters such as shorts.
* If you require a certain Ip grade such as low, medium, or high, please leave an order note/comment when submitting the order explicitly stating your request. You may do the same if you know the specific Ip you need in mA. We can see if we have something to match in stock.
Tested and/or matched by emissions on a fully calibrated Hickok TV-7 tube tester.
Industry standard for tolerance difference in matched sets of tubes is 10-15%. Our goal is to aim for 5% or less in all of our tubes. Some tube types vary in terms of their data range (low, medium, high Mu/Ip/etc.) and if 5% is not possible with a given tube/type, then we will use the industry standard 10-15% (15% being the absolute maximum before we will refuse to match the tubes, and quite rare for our matching standards).
A note on Psvane tubes
Psvane tubes are frequently sold only with factory matching or in proprietary Psvane packaging (ie. specially boxed pairs). We still screen, test, and match nearly all Psvane tubes ourselves in-house to our own high standards. This also allows us to offer them in different configurations such as matched trios or octets. Please see below in 'Factory testing and matching' for more information regarding factory tested and matched tubes that we sell.
Factory testing and matching
Nearly all of our stock is screened, tested, and matched in-house directly by us here at Viva Tubes. The only time that we are not going by our own test data is if a tube is explicitly stated to be 'Factory tested' or 'Factory matched' (ie. the Tung-Sol KT170 that we purchase directly as factory tested and matched sets. Larger sets are matched using the provided factory test data). Generally this is only done for industrial tubes or such high powered tubes like the KT170 as stated.