SOLD Step-up Transformer w/Cinemag 3440As and ground-lift switch
Will Ship To: Anywhere
Courtesy of Wojciech over at the Asylum, a pair of Cinemag 3440A transformers in a nice cast aluminum case (sorry, I thought it was steel), w/decent RCA's and a ground-lift switch. Good starter for someone (like me) getting started with low-output MC's. Works great at the 1:18 (150 ohm) tap for a Denon 103 or 103-R (and most low output moving coils) into a phono stage looking for an approx. 5 mv signal, give or take.
It's currently strapped to the 1:18 (150 ohm) tap. With the standard 47k input impedance of most phono stages, that works out to 145 ohms load impedance and about 25 db gain.
As an example, the BH Seduction w/C4S has 40 db gain, pretty typical for MM phono stages. At the 1:18 tap, a 0.25mv Denon 103-R with the combined 65 db gain drives pretty much anything out there without the need for an active line stage. I'm running that setup straight into a BH Stereomour (with just a passive volume control at the front-end) with great results.
Cinemag lists only the load impedance of their transformers, rather than listing the transformers' turn ratios. A Cinemag 3440A phono transformer has taps for load impedances of 37.5, 150 and 600 ohms. Those figures are the load impedance that the phono stage 'sees' from the cartridge. (Note: this is not the same thing as the internal impedance of the MC cartridge.) These stated cartridge load impedance figures of 37.5, 150 and 600 ohms are measured in reference to a hypothetical 50k ohm MM phono stage impedance. Dividing that reference input impedance of 50k ohms by the square of the turns ratio for any of the 3 transformer taps gives one of the stated load impedance values.
When solving for the turns (or step-up) ratios, you get (approx.) 9:1, 18:1, and 36.5:1. If you need less gain, try the 9:1 (600 ohm) tap. I wouldn't imagine you'd use this transformer for the 36.5:1 (37.5 ohm) tap. If you can afford one of those wonderful, pricey, super-low output MC carts that needs more gain, you're probably going to buy a Bob's Devices 'blue' Cinemag step up, which new goes for something like $1,175. (Instead, Wojciech lusts after a pair of Hashimoto's . . .)
Edited by DownhomeUpstate - 5/23/14 at 5:36pm