Connecting a Step Up Transformer


I've been reading Art Dudley's article in Stereophile regarding the Step Up transformers in the past two issue with great interest. I currently use a Shelter 901 (0.5mV) with an ARC PH3 SE. My preamp is the ARC LS25 MK I. With analog, I set the output at 24dB, but I still have to crank the volume all the way to the 12 o'clock or 1 o'clock position.

I've been thinking that a step up transformer might be the answer if I want to play with some other low output MC cartridges.

So I have the following questions:

1/ Currently the cartridge loading is set at 100 ohm on the PH3 per Shelter recommendation. If I add a transformer, does it mean I need to go back and change the loading on the PH3 back to 47k ohm?

2/ I take it that when you use a transformer, you will still have to match loading? So it is better to find one that allows you to adjust the loading?

3/ The PH3 only has 54dB gain. ARC recommended using MC cartridges with output higher than 0.6mV. So with a transformer, I should be able to resolve the gain issue, and also be able to use low output cartridges, ones with 0.3mV output, correct?

4/ What type of cable do you need to connect a transformer? I assume the phono cable w/ ground will just go into the transformer. How about from transformer to phonostage? Just a regular pair of RCA interconnects? Do I need a ground cable between the transformer and the phonostage? It would need to be the same length as the RCA cable?

FrankC
gundam91

Showing 2 responses by gundam91

ARC LS-25 allows you to select output for each of the sources at 12dB, 18dB, or 24dB. The CD source is set at 18 dB gain at the preamp, and I only need to turn the volume to about 9 to 10 o'clock position to get the same volume. (As compared to vinyl which is set at 24dB gain, and volume would be turned to 12 o'clock/1 o'clock position)

The issue with turning the volume to 12 o'clock and 1 o'clock position is that the background is not as quiet.

FrankC
Thanks for all the input. I will experiement with the volume and gain settings.

FrankC