NOS ECC81 Telefunken 6-7

New Old Stock rör ECC81. Telefunken i originalförpackning (plasthölje saknas). Made in Germany.

Tillstånd: Bra
Matchningsnummer:6-7

Vissa rör i öppnad förpackning samt vissa rör utan förpackning är testade med Orange Valvetester från Orange amps. Valvetestern indikerar om röret är Bra, Slitet eller Dåligt. Den ger dessutom ett matchningsnummer. Alla rör säljs styckvis på moodysounds.com och, om röret är uppmätt, anges dess tillstånd och matchningsnummer enligt Orange Valvetester. En utförlig beskrivning av matchningsnummer finns nedan. Kort kan man säga att ju närmare de två siffrorna ligger varandra desto bättre internt matchat är röret (dubbel triod). En 8-10 dubbel triod är ok matchat internt, en 12-12 är bättre matchat. En hög siffra betyder större gain. Siffrorna är också till hjälp om man vill ha ett matchat par, exempelvis två stycken ecc81 med nummer 10-10 kan anses vara ett matchat par.

Läs mer om rörmatchning med Orange Valvetester. Texten är kopierad från manualen från Orange amps.

”…the LED display indicates a ‘matching number’ which is based on a summation of the many results obtained during the test and has been specifically designed to reflect the operation of the valve, according to its normal function in an audio amplifier. For example, power valves are graded with their emission and control grid performance as primary factors, whereas pre-amp valves are graded with different parameters to reflect their role in signal amplification and phase splitting applications. If the valve is faulty or worn, then this will be indicated at the end of the test. The simplicity of operation belies what is going on ‘inside the box’, where a sophisticated microprocessor controlled testing system (incorporating DIVO Technology) is in operation, allowing full control over all inter-electrode switching and measurement operations. In addition all voltages required by the tester are internally derived, stabilized and controlled by the microcontroller, allowing rapid static and transient tests without generating unnecessary heat. The test algorithms used have been developed using data from tests on hundreds of new, used and faulty valves. We are passionate about valve technology and our aim throughout has been to make the Orange VT1000 a sophisticated, modern, truly portable valve tester which is primarily useful but also stylish, appealing to all valve users whether amateur, professional or in the music retail trade.”

”VALVE MATCHING VALUE
A ‘matching number’ indicated by the LED(s) at the end of the test, is based on a combination of measured parameters to give an indication of how the valve will perform, according to its typical function in an amplifier. After the valve has been tested, the tester will assign a matching number ranging from 1 to 15. Basically: the higher the value, the higher the gain of the valve. If a number of valves are tested, the gain or ‘matching valve’ can then be used to group together pairs or quads of valves. For example if two EL34s were tested and both passed with a 10 ‘matching value’ then these valves could be considered as a matched pair of EL34s. Specific tonal variations have been noted, even between closely matched, fully serviceable valves having different ‘gain’ groups, even produced by the same manufacturer. The VT1000 matching number can provide a way to ensure that the amplifier has a consistent tonal quality even after the replacement of one or more valves.

Double triode (pre-amp valves) have two valves inside one envelope i.e. an A & B side. After the VT1000 has tested a double triode (providing that the valve passes) two matching value LEDs will illuminate. For section A the LED will flash and for section B the LED will be constant. If only one constant LED is illuminated, this means that both sides of the valve are the same. In general, the closer the LEDs are together the better, if two matching valves are apart by more than 6 values the VT1000 will fail the valve.

Sometimes new valves don’t give high matching numbers; does this mean that they are still OK? Normally, yes – In general, a higher number indicates a newer or less worn valve, however due to manufacturing tolerances, a range of values are possible, even with new stock. Manufacturers of amplifiers design their products to accommodate these normal tolerances without any deterioration in performance. When fitting power valves in pairs or quartets, the closeness of the number is much more important, as mismatched valves will directly impact the sonic performance of the amplifier. Pre-amp valves are often ‘double triodes’ i.e., they have two identical valves in the same glass envelope and close matching of these two ‘halves’ is very important in some parts of the circuit.”