15095 vs 15095A

[hasbeen]

Is there a difference between the Altec Peerless 15095 and 15095A transformers? Thanks!

[bfish]

The 15095 xfmr core and can are internally tied to pin 8, which is also one end of the 15k winding, therefore limiting its application to those where the hi-Z side of the device is (or should be) at earth ground potential, such as is used in single-ended devices. Improper application of this xfmr can cause serious problems, including equipment damage.

The 15095A xfmr core and can are internally tied to pin 2, which has no connection to any of the windings, therefore allowing greater flexibility in its' use. A jumper from pin 2 to 8 will make it the equivalent of a 15095.

Both versions saw application as line-level input AND output isolation devices. Both exhibit the same bandwidth, being extremely flat from 30 to 15kHz, with a 3dB/octave rolloff both above and below.

There seems to be signifigant confusion regarding the use or even the need for isolation xfmrs in home applications. One needs to keep in mind that most of the gear that has provisions for isolation xfmrs was designed for use in theaters, auditoriums, and such locations where various system components are located at signifigant distances from each other, and often on different legs of the house wiring. In such installations, signal isolation becomes mandantory. For home use, often the only place isolation is needed is at the interface between consumer (-10dB, hi-z, unbalanced) and pro (0dB, lo-z, balanced) equipment, though isolation alone is usually insufficient to maintain low-noise signal integrity. Judicious selection of the proper matching device for the application can often eliminate the need for any active components at the interface.

While Altec/Peerless line xfmrs are among the finest ever made, one should note that ALL xfmrs degrade the signal to varying degrees. Used correctly, they can reduce noise and maximize gain. When they're not needed, simply install the proper jumpers in the octal socket provided (instead of the xfmr) to pass the signal straight through.

[Steve Schell]

According to Joseph Esmilla there is a difference in their grounding schemes. He discusses this on his very good web page on using microphone transformers as moving coil phono stepup devices.

http://members.myactv.net/~je2a3/mic-mcstep-up.htm