Mullard / EL33-MULLARD

EL33-MULLARD Click on image(s) above to view larger
£65.00

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The Mullard Radio Valve Co. Ltd was founded in 1920. In 1923,to meet the huge consumer demand in electronics Mullard entered an agreement with Philips of Holland and by 1926 Philips bought Mullard and established one of the greatest valve manufacturing companies in world history.

They developed many iconic valve such as the ECC83, EF86, EL34,EL37, EL84, GZ34 and GZ37.These are regarded as the best valves of their type ever made and original Mullard items are high prized by Musicians Broadcasters and Audiophiles the world over due to their sound quality. You can see how these valves were made on the front of our website in the Blackburn storey.
Original Mullard EL33 ouput pentode was used in domestic low power amplifiers and radios. These come in the original Mullard Blue boxes.

I have had many emails from Leak TL 10 owners regarding that is an equivalent to a KT61. It is NOT a straight plug in replacement as suggested in some books.

The KT61 is referenced working with a cathode resistor of 90 ohms and grid bias of -4.4 vdc, with gm of 10mA/V, anode current 40mA, 4.3 W output.

EL33 is referenced with cathode resistor of 150 ohms and grid bias -6 vdc, gm 9mA/V, anode current 36mA, 4.0 W output.

So it needs a minimum bias swing of at least of -1.,6 vdc.

The EL33 needs a cathode resistor of 150 ohms at least, while the KT61 needs a cathode resistor of 90 ohms. If this is not changed then you will fry the EL33 as it will run far to hot. So without changing the cathode resistor to a least 150 ohms a and minimuim of 1 watt type ( found normally between pin 8 and ground chassis) and a minimum bias swing of at least of -1.6 vdc the EL33 cannot be used to replace the KT61.

The KT61 has no direct replacement so with a bias adjustment the Mullard EL33 is the closest that we have found.
These are brand new and come in the original Mullard Blue boxes


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