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Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ.

RE: Hammond 193L Choke Tweak Revisted

I have 2 sets in each of my 2 systems... 1 pair for each systems main audio EQ AC, another pair for the 'dirty' HW & related EQ.

Each set has 2 of the chokes... 3 of them are a 193L/193M pair (as pictured), the 4th, on one system's dirty side is just a pair of 193Ls (I found a good deal on 2 more 193Ls and didn't want to pop for another 193M).

I pull the endbells off and mount them with brass hardware on a bamboo base. The screws can be tightened to help control humming, but I've had 1 or 2 hum such that tightening the mounting screws down did not cure the hum and I had to replace them (just like your experience, Rick... hi, BTW!). And the nut on the bottom of each is a rounded acorn nut (also brass) so they have some coupling to the floor.

Before I wire them up I try them both ways on the AC line (1 line to hot, the other the neutral, then reverse) and measure the AC leakage voltage from the laminations to the outlet's ground. I wire them with the orientation that gives the lowest measured voltage, just as I do with any power transformer. BTW, I forget which way Alan M suggested you wire them (to the short wire or long wire, which distinction of course disappears when you remove the endbells), this has been consistently opposite of his recommendation. Go figure!

The set pictured was an early configuration where I had a separate power cord and outlet for each of the two chokes. Now they just get wired in parallel. On the main audio EQ AC's, they are inline on the DIY AC power cord (12 gauge 4-cross braided with spiral ground) that goes into a PS Audio P10. On the 'dirty' EQ AC's, they are at the end of a DIY extension cord sized to reach to a nearby outlet on a different AC circuit and breaker.

Best I can do in this house without a major rip-up for dedicated lines... maybe someday!

I top each choke with an almost small-fist-sized raw sodalite stone. That was a recommendation by someone on this forum a few years back (Carcass maybe?) and has worked well for me. AND a lot less expensive than the Mad Scientist stuff, though probably not as good.

Before I wired them up inline on the AC power cords on each system's main audio EQ AC, I would just plug them into the 2nd outlet in that pair. Occasionally when I'd unplug for a thunderstorm, I'd. forget to plug in the chokes... and the system never sounded right until I did.

I don't expect to ever be without them!! Or the P10s, which make a huge diff in each setup.

Greg in Mississippi

P.S. On the topic of isolation transformers, there is some buzz on CA where Uptone Audio has recommended that in conjunction with using one of their fully isolated from the AC LPS-1 Ultracap power supplies, to use a low-interwinding capacitance isolation tranformer appropriately sized for their entire system and plug everything else that is not isolated into a low-impedance non-filtered outlet strip on the output of the transformer, removing all fancy AC filter setups. The low-interwinding-capacitance iso transformer provides both surge protection and noise filtering inherently.

This has seemed to work well for those who have tried it, none have said they are going back to their power filters, even pretty expensive ones.

I plan to experiment with this someday, with the ones on the main Audio EQ ACs' before the P10s. I think it will be complementary, but don't have a spare $1k or so to spend on the iso tranformers right now.

Everything matters!

Edits: 01/04/17 01/04/17

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