Phono stage changes

I have used a Musical Surroundings Phonomena II+ as my phono stage for about two years now, I’m thinking.  My preamp is a line stage, as most today are.

When I originally was shopping for tube preamps, I was leaning towards getting one with a phono stage built into it.  But the more I’ve thought about it in recent years, I may go a few days between playing vinyl, with the preamp running sometimes 8-10 hours per day. I would have been burning up the life of the tubes in the often-unused phono section had I gone that route.

The Phonomena II+ did sound good, yet something was bothering me–background noise.  I am using the Audio Technica ART7 moving coil cartridge, which has a very low output of 0.12mV.  With the Phonomena’s gain set to maximum, sadly the noise of the electronics (that low “rushing” noise of amplification) was audible above the surface noise of the quietest records I own.

I had two phono stages on my short list–the Rogue Audio Ares (preferably the Ares Magnum with upgraded Cinemag step-up transformers), or a Conrad-Johnson EV-1, which matches the rest of my C-J-based system.  As luck would have it, my “wanted” post on US Audio Mart resulted in a hit within 48 hours, and it only took an extra day or two before I took up the seller on his offer and had it shipped in.  It arrived, in beautiful condition, a bit dusty inside, but nothing a careful cleaning won’t take care of.

Now, keep in mind I do not yet own a step-up transformer.  All I could cobble together was an ancient Musical Fidelity AC-1 pre-preamplifier I had on hand.  I got everything connected, and noticed a couple of things.  First, that AC-1 is one sensitive little beast–it picks up hum from just about anything.  I finally had to half dangle it off of a nearby shelf to minimize the hum.

And through the EV-1, the sound of everything connected was rather lackluster.  But I kind of expected that.  I don’t know how transparent the AC-1 is but more importantly, these are apparently the original tubes in the EV-1, and it did sound kind of tired.  It did sound a little better after using it for a couple of hours, but it wasn’t where it needed to be.

Time to replace the tubes.  The EV-1 uses two 12AX7, one 12AU7, and one 5751.  Uncle Kevvy to the rescue–I decided to try some Gold Lion 12AX7s and a 12AU7, and one Tung-Sol 5751 from Upscale Audio.  I did see a note on about some earlier C-J preamps being hard on the 12AU7, and didn’t quite get a straight response from Upscale about my concerns (the email, to be fair, wasn’t directly from Kevin Deal).  So I ordered the 12AX7s and the 5751 from Upscale. I’m using his same Tung-Sol 5751 recommendation in my C-J power amp and it is sounding excellent.

A long couple of days of Internet digging turned up the Brimar CV4003, which is the British military equivalent of the 12AU7, and happens to be Uncle Kevvy’s favorite 12AU7.  I ordered two, one as a spare, and they are en route to me from Turkey (of all places).  And the price was very reasonable. In fact, I may order a couple more spares next month, along with another matched set or two of spares for the preamp (which uses the Mullard CV4058/M8080–by far the best 6C4 variant I have used).

That leaves the SUT.  More digging. I fancied making my own with existing transformers, but ended up buying a kit from a small place called K&K Audio. They are a US distributor for the Swiss-made Lundahl transformers.  I spent a couple of weeks digging for the right transformer ratio to use with my ART7, and finally settled on 1:20, which will give me the gain I am looking for, plus the load impedance is almost dead on where I wanted it (120Ω, and the combination works out to 117Ω).  I ordered the K&K kit version with the Lundahl LL9226.  One deciding feature was that K&K’s kit allows me to set the step-up to any one of the three ratios it offers (1:5, 1:10, 1:20), so I am future-proofed when I get a higher-gain cartridge in the future.

Finally, I’ve added a set of Vibrapods and Vibracones to the mix, and those are arriving here soon as well.  The EV-1 proved to be slightly microphonic on its old tubes, so these will help.  (I’ll have a separate post on the Vibrapod/Vibracone system once I get them all in my system.)