Mullard Mustard Capacitors

Mustard capacitors are a type of film capacitor that was originally developed in the 1950s by Mullard, a British electronics company founded in 1920 and sold to Philips in 1977. They are characterized by their beige colour and their tubular shape. Mustard capacitors are made with a thin layer of metallized polyester film. It is then rolled and inserted into a tubular case. The leads are then attached to the ends of the capacitor. Mustard capacitors are reputed to have excellent sound quality and were extensively in guitar amplifiers from the 1950s to the 1970s. They have a low fail rate and can still be found working perfectly in guitar amplifiers that are 60 years old.

They can be found in hundreds of vintage guitar amps. Many manufacturers including Marshall, Watkins Electric Music, Hiwatt, Orange, Vox and many more. Too many to list in this post.

What are they used for in a guitar amplifier circuit?

They are used for blocking DC voltage and only allow AC voltage to flow through the circuit. These capacitors seldom leak DC voltage into the circuit. They are extremely rugged capacitors.They are also used in tone stacks.

Can you still buy these capacitors?

Yes, you can still find Mullard Mustard Capacitors being sold as new old stock by Vintage Electronics. . These are reasonably priced.

There is also a couple of reproduction Mustard capacitors:

• SoZo Mustard Cap™ Capacitors
• Mallory “Mustard” Capacitors

You can find more information on SoZo capacitors by clicking the link: Sozo Capacitors. Be prepared to shell out some hard-earned cash if you are planning to use these in your guitar amplifier.

Here is an ecommerce link to Mallory Mustard capacitors.