MY MICROPHONE SOUNDS LIKE SURF (or the OCEAN).
You probably have a bad tube.
CAN I CHANGE THE TUBE MYSELF?
Yes, but it should be a microphone select grade tube, and all tube mics except the 407 & 507 require adjustment of the heater voltage. The mic must be fully disconnected from the power supply which should be turned OFF before engaging in this process. Use gloves if possible, to avoid oily hand contamination of the high impedance tube and circuitry.
WHAT IS A MICROPHONE GRADE TUBE?
A tube selected for use in a microphone which has the characteristics of low noise, low microphony, and adequate gain. Tubes are preselected, burned in using a proprietary process, and then re-tested before final approval. Since the world's supply is not what it used to be
WHAT TUBES ARE USED IN YOUR MICS?
We currently use 6201's, or ECC801s', as well as EF800's and EF814k's. We reserve the right to change tube types in any model at any time.
WHY CANT I FIND A DATA SHEET FOR THE EF814k ONLINE?
EF814k is our designation for a supreme microphone select NOS (New Old Stock) Telefunken tube, and we do not control the internet.
WHAT IS NOS?
NOS stands for New Old Stock. It differentiates tubes that were made during the apex of then free market vacuum tube manufacturing in the USA, Germany, England, and France from currently made Russian and Chinese tubes. We have not yet found any currently made tubes that come close to the composition, construction, and vacuum of NOS tubes.
HOW LONG SHOULD I EXPECT A TUBE TO LAST FOR?
Our tubes are warranted for a year from original purchase date, and should be expected to last for years beyond that. Though we try, and since the world's supply is not what it used to be, we can't always find tubes that will last for thirty or sixty years as could be found during the heyday of vacuum tube manufacturing.
MY EARLY BOCK 251 HAS A 5670 TUBE THAT HAS GONE NOISY, WHAT SHOULD I DO?
We have since converted the mic to 6201/ECC801S, which is a much more common pinout to install replacement tubes into. Have our shop convert the mic to the new pinout and you will be able to replace the tube yourself if you like. Microphone select 5670's are hard to come by, so your chances of long mic life increase when you convert to the 6201 pinout.
WHAT TUBES WERE USED IN MY SOUNDELUX MIC?
Please see the “Soundelux Microphones FAQ”