P EARL , I NC . - Electron Tube Coolers for Increased Service Life . . . . P EARL T UBE C OOLERS have been doubling the service life of hot-running audio vacuum tubes for nearly 30 years, during which time over 300,000 pieces have been fitted into audio systems the world over.



. . . . Perhaps the longest running, best documented, best warranted and most successful tube audio accessory of all time P EARL T UBE C OOLERS have inspired several much more costly imitators; none of which combines the functions of cooling and microphonic reduction, nor anything like the cost/benefit ratio achieved by the long-established P EARL design.



. . . . Continuously refined, our heatsink design has evolved from an oxide blackened, louvered fin device with black EDPM O-rings  later found to have inadequate long-term thermal withstand  to the present day solid copper device with 3D -contoured, contiguous fins coated with 2 mils of high metal content, high temperature powder coat and held in place by high thermal withstand, red-orange, silicone O-rings.



. . . . With heat from the within tubes envelope and pressure from the external O-rings the powder coat slightly softens to then flow in a conformal manner with an intimate thermal interface and unmatched microphonic control resulting.



. . . . Based on research begun in the early 1950s by the US military and the aeronautics industry, P EARL coolers achieve the sorts of glass temperature reductions shown over 60 years ago to greatly increase the operating life of soft-glass enclosed electron tubes.



. . . . Determined during the 1950s research is the fact that the soft glass typically used in receiving tube manufacture is susceptible to high temperature operation in that it becomes effectively porous at elevated temperatures, thereby allowing atmospheric contamination of the high vacuum within the glass. By several extensively researched and solidly confirmed mechanisms such contamination has been shown to have destructive effects on the electron emitting surfaces upon which tube functioning is completely dependent and extended service life relies. . . . . All major vacuum tube manufacturers of the day clearly illuminated the benefits of envelope temperature reduction.



. . . . In a Nov. 1959 data manual Brimar Valves, UK stated:



. . . . The use of close-fitting screening cans of high thermal conductivity in intimate thermal contact with a large area of the [soft glass] bulb, in conjunction with an adequate heatsink can materially reduce the operating bulb temperature and very considerably improve the life of the valve.



which is an exact description of the P EARL electron tube cooler's form, function and effect.



. . . . The 198 pg. P EARL Audio Note, P EARL T UBE C OOLERS and Equipment Reliability provides both a present-day overview and several magazine reviews as well as an extensive overview of the period literature and patents. It can be downloaded here while a 3 page Quickstart Introduction is available here .





. . . . As of Jan. 1, 2017, P EARL T UBE C OOLERS are underwritten by a lifetime, transferable end-users' warranty that is also retroactive, meaning that every P EARL cooler in the hands of an end-user is now warranted against defects in materials and/or workmanship.



. . . . If your coolers have black O-rings, please contact us for no-charge, replacement high temperature, silicone O-rings.





. . . . Dealer inquiries are welcome, we have distribution openings in some countries and will advise. Tube Coolers for Small Signal Tubes.

Sizes, fitted tubes, cooling specs & minimum "glass-to-glass" spacing. Type: MCF-7 Fits Tube Types: 6AU6 6136 6J6



MCF-7: 7-pin Miniature

Cooling Performance Buy this

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eBay Type: MPCF-7 Fits Tube Types: 6005 EL90 M8245



MPCF-7: 7-pin Miniature Power

Cooling Performance Buy this

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eBay Type: MCF-9 Fits Tube Types: 12AT7 ECC81 12AU7 ECC82 12AX7 ECC83 6DJ8 ECC88 6AN8 7199



MCF-9: 9-pin Miniature

Cooling Performance Buy this

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eBay Type: MPCF-9 Fits Tube Types: 6BQ5 EL84 6CL6 EL86 6FQ7 6CL6 12B4 12BY7



MPCF-9: 9-pin Miniature Power

Cooling Performance Buy this

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eBay Type: OCF-8 Fits Tube Types: 6SL7 5691 6SN7 5692 6SJ7 5693 6BX7 6BL7 Buy this

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Tube Coolers for Power Tubes.

Sizes, fitted tubes, cooling specs & minimum "glass-to-glass" spacing.

Type: PCF-125 Fits Tube Types: EL34 KT77

PCF-125 Cooling Performance

Convection and Fan Cooled

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Type: PCF-150 Fits Tube Types: GE - 6550 Sylvania - 6CA7

. EL519 EL509 6L6 5881 KT66 6LF6





PCF-150 Cooling Performance

Convection and Fan Cooled

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Type: PCF-175 Fits Tube Types: Svetlana

Winged "C"

6550A/B/C Ei - KT90A/B/C Buy this

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Type: PCF-200 Fits Tube Types: KT88 8417



PCF-200 Cooling Performance

Convection and Fan Cooled

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eBay Type: PCF-250 Fits Tube Types: 6C33C 211 805 811 813 845 Buy this

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