Home


Scott 265A Amplifier
    Laboratory Power Amps HH Scott

 

HOME

FOR SALE & GALLERY RADIOLA INFO WHAT'S NEW RESOURCES
LINKS AT AUCTION INFORMATION CONTACT updated 8/05/2017

265-A #1


265-A #2



  
HH Scott Laboratory Amplifiers

    model 265A mono Power Amps

click on small images to enlarge

From the early 1950's in great original cosmetic condition. These are very clean, no rust or corrosion and all silk screening is in very good condition. I have just completed an electronic restoration and they work perfect. These amps are so rare that there is very little technical information on them. I have managed to secure and re-master the only published technical bulletin/owners instructions that I'm aware of plus a schematic. Reprint instruction manual available


The literature boasts the following features:

  • Dynamic Power Monitor - (protect speakers from overload & burnout)

  • Variable Damping Control - (permits electronic control of damping)

  • Class A circuitry throughout

  • First order difference tone intermediation of less than .1%

  • 70 watts music power (65 watts continuous)

  • Multiple output impedance - (2, 4, 8 & 16 ohms)

  • Both high & low level input jacks - with variable input level control
     


Here's what the electronic restoration involved:

  1. First I un-did some electronic modifications that were done by someone in the past.

  2. I carefully restored the electronics to the specifications of the schematic that was drawn by the HH Scott Co.

  3. New tubes, capacitors & power cords have been replaced.

  4. I made three modifications to the circuitry of each unit as follows:

  5. One; was to install a surge resistor in the power supply B+ line.

  6. Two; modified the output tube's cathode bias circuitry to obtain the correct filament voltage for the two 12AX7's.

  7. Three; the power transformer was designed for a lower AC line voltage than what's supplied to most of our homes today (mine is 121 volts). This made the tubes run quite hot as not only was the B+ voltage elevated, the filament voltage was also quite high. Since there are no taps on the power transformer's primary, I solved the problem by installing a bucking transformer in the power transformer's primary. This devise is carefully installed and hidden under the chassis. It can be seen on the underside images of the amplifiers just above the power transformer's terminals.

There are minor physical differences in the two amplifiers. One has a holder for a spare line fuse, one filter can and has no serial number. The other has no such holder, has two filter cans and a serial number of 2119. The chassis colors vary a bit also. The transformers and circuitry are the same in both units.

< Reprint manual & modification info available

< beautiful  replica Pam clock available

the 265A is no longer available

RadiolaGuy.com
© C.E. Clutter

Home

Member of:
Northwest Vintage Radio Society

Member of:
Antique Wireless Association

return