Eminent Technology ET-2 Tonearm Owners

@ct0517  I don't have a straight in loom like you.  My loom is terminated in a Cardas phono box with RCA fremale plugs.  From the box to preamp I'm using 1 ft lengths of unshielded silver interconnect.   The phono inputs on my preamp are on the side of the preamp closest to the TT (not on the back).   Following your suggested diagnostics, moving the loom around has no effect on the hum.  Moving the interconnect varies the intensity of the hum.  So, if my assumption is correct and EMI is the culprit, it is being picked up by the ICs and not the loom.  Of course, the ICs are closer to the preamp than the loom.  

Acoustic feedback.  Yep, I've got it.  At listening level, however, it is nearly nonexistent.   But, correct me if I'm wrong, the acoustic feedback is distinct from my hum which is there with no tapping and no noise in the room and without the stylus on the still record. It's just another issue for me to obsess about. Right? :)

@ct0517,

Most of you posts, that are reminders of what others may have said, are greatly of use to your posts that may affect others.

Harry,
I came to a conclusion long ago, that this interference is not one large cloud that fills the room. It is pockets of smaller clouds, or picture those laser beams that protect valuables in a vault. This is obvious as you the move the interconnects and the levels change. The trick is to move the wires/IC’s between these pockets, lines of interference. One needs to be the most anal with wiring arrangement, especially with a turntable, when using Single Ended. Imagine using Single Ended with a large Class A amp that uses 450 watts at idle. With all that current there at idle, if there is a cable in a not so great position, this large amp coming to life will tell you.

Shielded IC’s color the sound and take from the small phono signal. It gets absorbed into the material. Depending on the cable manufacturer you get varying colors. This is going by memory from years ago but is as clear as if it was yesterday. I still do own Purist Audio interconnects. I have multiple looms. My first stock ET2 bypass went just past the turntable to the phono box ...then the Purist Audio IC’s to the preamp. I am not saying it did not sound good, but the straight in just good wire loom destroyed it. The Purist Audio IC’s are kept around for the Dynavector tonearm on the Jean Nantais Lenco TT.

If you did one day go to a straight loom, you would need a very short one based on how your gear is set up. This is good. The location of the phono inputs on your preamp is ideal. You want it coming off the tonearm, dropped down and then back up to the preamp. A happy face loop. So it helps if your preamp is on the same level with the turntable to help create that loop. Your performance in audiophile speak would go more live, immediate - Just saying. One of the things the straight loom brings. The ET2 begs for a straight loom with its design. I run mine outside of the tonearm entirely and braided along the armtube to reduce interference. The arm is set up in its entirety without wiring, then the wiring gets added. That way I know there is no wiring effect altering setup which it does do. The ET2 bearing is just too smooth, slippery. Some pull their hair out on setup due to this.

***********************

Acoustic Feedback is always there, and with a turntable cartridge picking up this feedback and sending this signal through, it can create havoc as we know. Any turntable set up on a suspended floor, main floor, is not ideal and you will need to use various "band aids" to fix the sound. I knew one guy whose turntable set up was good, but his subwoofer was placed between the suspended wood beams that supported the floor. It sent vibrations through the floor to his table.

Good morning Chris,
Thanks for the thorough analysis.  You may just sell me on a loom yet.  My current ICs are so short there is no room to move them more than a couple of inches.  I have a second set that are a little longer I will try moving around a bit.  Yes, I've read the posts and reviews that talk about shielding and coloration.  The Grover Huffmans, however, do get some terrific user reviews.  I should have them next week and will let you know what I hear.

As for the feedback, your idea regarding subwoofer placement is interesting.  I'll try moving mine around.  I don't think I had the feedback with the spring suspension on the HW-19 but I really like the stability and modest sonic improvements the Herbies Tenderfeet brought to the TT.  

Most frustrating is although my two TTs are only two feet apart the Garrard rig is dead quiet and has no feedback.  If a Platine appeared at something I could afford, my VPI would be history.

@vpi: regarding hum:
The Delos has ca. 2.5 dB more output than the Black Beauty in low output configuration, with a quite low source / coil impedance. I suspect the vdH is more in the range of 20-30 Ohms.
I was & am amazed that this information is lacking in all sources I could find, be it van den Huls website, be it eg. Stereophiles / Sculls review! The source impedance is an absolutely essential technical information, as essential as the outpult voltage. There are two reasons:- Stray capacitance couples the static mains voltage field into the tonearms signal wiring and forms a RC voltage divider, the R provided by the source impedance - in this case the source impedance of the cartridge. Ie. a lower source impedance shorts more of the coupled mains field to ground. Shielding should shunt this voltage proportionally to the degree of shielding, and by adding a higher capacitive impedance against the external field.
- For MC transformer compatibility, source impedance is the key parameter (not voltage) - it makes or breaks compatibility.

Assuming a 3x source impedance, this increases stray hum coupling by 9.5 dB, which would result in 12dB more hum with the vdH than the Delos, based on simple and precise signal calculations.
The key issue comparing cartridges is the relationship of the voltages vs. the relationship of the source impedances. This defines in essence the relative hum levels.
Rel. low impedance / rel. high voltage are desirable. The Koetsus are quite good there, with Delos and others. Jan Allaerts and vdH (?) are more tricky in that regard.

Add to that, that the signal shield of the ET2 must be open for the "mobile" wiring loom. The Ortofon arm is almost completely shielded, except maybe 5 mm with visible wires in the horizontal bearing.
In my free external wiring of the ET2 I added a very thin wire from one of the fixing collars of the arm to the ground post. This helps, but not totally cures it.

- A bright timbre of the hum signal hints at stray field coupling (capacitive)
- A dark timbre with sometimes some nasty low harmonics hints at a ground loop, ie. magnetic coupling.