Western Electric MIRROPHONIC

Western Electric MIRROPHONIC

WE25a horn and WE555W.

Jensen-Erpi Ta4181a 18" 24V field coil woofer.

Motiograph se7018 network : 16 Ohm 400Hz (?) network

Flat baffle 170x120cm

The field coils of both woofer and driver are supplied by a Motiograph Tungar PSU

WE555W and WE555 differs only in diaphragm. WE555W was manufactured till 1931 and has a lighter duralumin diaphragm : very good treble response. WE555 , manufactured after 1931, has a heavier ,rugged aluminum diaphragm : warmer sound.

This Mirrophonic style system sounds very clean and straight . Its frequency response is very flat . Its sound is beautiful but less exciting and lifelike in respect to the we15a system.

The we555W response on trebles is very smooth but it's flat till only 6000Hz. I boost the 6000-13.000Hz region employing the treble control of a Scott 121 preamplifier. In this way treble balance and energy is correct , the trebles have a better dispersion due to multicell pattern and I can avoid to employ a tweeter with its related network and phase relation . Due to only 2 way system , sound coherence is reached.

JENSEN field coil speakers

Jensen ERPI ta4181a 18"

Field coil : 24V , voice coil impedance 12 Ohm .

Western Electric never manufactured his woofer during 30's , but they were Jensen made. WE Ta4181a and Ta4194a were Jensen made under ERPI spec. ( Electrical Research Product Inc ).

WE ta4181a and ta4194a were Jensen 18" with field coil magnet at 24V and 10V respectively.

Jensen instead usually made for pro and home audio purposes the same 18" speakers but with High voltage field coils ( from 100 to 300V) and lower voice coil impedances ( usually 8 Ohm ) . They were Jensen L18 , M18 , V18 and HF18.

Jensen M10.

The Jensen M10 has the same magnet of Jensen 18" , but cone is 13.5". M10 has bakelite spider instead Jensen 18" has cloth spider.

This speaker exists in many versions ( M10 , V10 , M20 , ERPI TA4151a ). The main differences are inbuilt or not PSU , field coil impedances. Usually this speaker has 8 Ohm voice coil. Instead WE ta4151a has 11 Ohm voice coil.

This is a widerange speaker , usually employed in console radios or studio monitors. WE ta4151a was used fullrange or with we597a tweeter added or as bass speaker on we15a systems.

The sound of M10 is really beautiful , fast , clean , very lifelike. Probably one of the best cone speakers ever made.

Jensen and Erpi 18" and 13,5" speakers are made in modular way.

The magnet housing is always the same and is fitted with various field coils ( high or low voltage). the basket comes with his own cone , spider and voice coil. The basket assembly is bolted to the magnet housing with 4 bolts. So when a cone brokes , was replaced the entire basket cone assembly , just bolting it : no cut or glue needed.

In photo at left there the 2 style magnets employed on ta4181a. At Right one ta4181a with ERPI style magnet. Ta4181a were supplied both with ERPI and Jensen pedestal style magnet housings. Same sound and data.