DB Systems DBP-6MC Resistive Loading Kit

This whole thing started up again when I tried to improve the phono-input section of my main system—not to enhance its performance (although you might expect that to happen), but to provide a fairer, more flexible context for evaluating new cartridges.

The technical reason: Taken in isolation, even the small collection of phono cartridges that I own—Miyabi 47, Rega Elys, Grace F9E, Denon DL-103, and EMT OFD 25—represent a pretty wide range of resistive-loading requirements. The low-impedance Miyabi 47 and the high-impedance Denon DL-103, for example, couldn't be more different from one another, despite their similar outputs.

Now: Having cast aside most of the cartridge-alignment tools I've bought over the years—the Cart-A-Lign, the Geodisc, the Dennessen Soundtraktor, various incarnations of the WallyTractor—in favor of the elegant, accurate, and easy-to-use DBP-10 alignment protractor, my phono-accessory thoughts turned once again to that product's manufacturer, DB Systems (footnote 1). So in February I ordered their DBP-6MC Resistive Loading Kit, an ancient but eminently serviceable thing to have, and very affordable at $49.

The DBP-6MC kit is based around a pair of flexible Y-adapters, each having two phono sockets at one end and a single phono plug at the other. The idea, of course, is to plug the Y-adapters into the phono inputs of your preamp or integrated amp, then to plug your left- and right-channel tonearm leads into one leg each of the two phono-socket pairs. The remaining sockets can then be loaded with your choice of resistive plugs (also included), to provide a specific value in parallel with your phono cartridge. The DBP-6MC comes with five pairs of color-coded resistive plugs: 10, 20, 50, 100, and 200 ohms. Using any of those values in parallel with 47k ohms will greatly decrease phono input impedance overall, allowing the cartridge's "motor" to electromechanically damp itself. The DBP-6MC also includes an "empty" pair of plugs, into which you can solder the alternate resistor values of your choice.

I pause here to confess the selfish sub-motive lurking beneath all the self-congratulatory twaddle about "fairness" and "flexibility." My reference preamplifier, the damn good Shindo Masseto, has two pairs of phono inputs: one for moving-magnet cartridges, the other for moving-coil, the latter providing additional gain and appropriate loading with a pair of custom-wound Lundahl transformers. (I don't know the specs of those transformers, but because they were said to be designed around the low-output Ortofon SPU series of pickup heads, it's a safe guess that their primary coils are of low impedance and their impedance ratio is high.) As I mentioned above, I also own an EMT OFD 25 mono pickup head: a wonderful-sounding MC device, but with gain so high that, when I use it to drive the Shindo's MC inputs, I'm forced to turn down the volume controls on my Shindo monoblock amps just to keep the resulting loudness from blowing my scalp free of the rest of my head, Mr. Weatherbee style.

Yet while the gain provided by the Masseto's MM inputs would seem ideal for use with the OFD 25's high output, the 47k ohm load impedance wouldn't. Indeed, EMT's distributor recommends for the OFD 25 a load between 100 and 300 ohms.

Thus I reasoned: What could be better than to use the 100 or 200 ohm plugs of the DBP-6MC, alongside the EMT pickup head, into my Shindo Masseto's MM inputs? That would surely sound heavenly.

I began by revisiting the EMT OFD 25 straight into the 47k ohm inputs, with the DB Systems Y-adapters in-line but without extra resistors in place: That experience refreshed my memory of how tonally off-kilter the sound was the last time I tried it. After that, inserting DB Systems' various resistive plugs was a simple enough matter—doable even with the volume turned up.

But the 200 ohm resistors only made my records sound deader and duller, stripped of musical life and sonic presence alike. So did the 100, 50, 20, and 10 ohm plugs, to even greater degrees.

In every sense, used in parallel with every loading resistor at my disposal, the MM inputs on my Shindo Masseto didn't sound good with this high-output pickup head: I appeared to be stuck using the much-better-sounding MC inputs for the rest of my life—oh, the drudgery—and having to compensate by turning down the volume whenever I wanted to hear my mono records.

But the DB Systems resistive-loading kit will stay. I'm a loading believer—47k ohms on an MC cartridge is for people whose hearing is shot beyond repair—and I remain convinced of the kit's future usefulness, although I continue to believe that the load presented by the coil of a transformer to the coil of a cartridge will always be better still: empirically superior, howsoever mathematically non-analogous. In any event, I'll be happy to trot out the resistors whenever a cartridge manufacturer requests them.

Company Info
DB Systems
PO Box 460, 214 Main Street
Rindge
NH 03461
(603) 899-5121
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mw679's picture
Loading Kit with SUT

Thank you for this review, just came across it as I was looking for more information on this particular kit from DB Systems. Can this be used with a step up transformer? Would the y adapters still connect to my phono input on my receiver with my cables from my SUT connecting into them intstead of the turntable leads directly? I've been searching for an answer on this but haven't come across any info yet. Thanks again.

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