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RE: Humming from Maxxed Out Phono Preamp

Posted by elg (A) on April 15, 2017 at 09:13:53

In Reply to: RE: Humming from Maxxed Out Phono Preamp posted by KevinC on April 14, 2017 at 18:44:18:

Hi Kevin,

Thanks so much once again for taking the time to respond to my issue. Here is a reply quoted verbatim from Pass Labs' technical support team:

Quote:

" With a phono cartridge by the time signal makes it from the cartridge to the speakers we're looking at gain ratios of over 1-million :1
Any electrical field in the vicinity has potential to be picked up and amplified along with the signal of interest. With gains running a million to one some care is necessary.

DISCUSSION:
1) Turntables like Rega with non metallic plinths offer no shielding from magnetic fields, don't put them above any devices with larger transformers.
2) Many tonearm cables are un-shielded, keep them away from AC power cords, and devices with transformers, if you must cross an AC line, do so at 90 degrees.
3) Do not bundle or wrap AC cords into loops, loops focus and intensify fields.
4) Grounding. Typically there are aux ground lugs on the back of phonostages. These typically must connect to some metal on the tone arm. Your INT-60 likewise has a white ground lug on it's rear panel. That may need a wire to the ground terminal of your K&K phono.

The K&K being a transformer coupled device may look like an isolated ground or un-grounded source to the INT-60. Sorry not really sure how the K&K is wired internally, but it does have an external ground connection and potentially both the tonearm and INT-60 would benefit from being star grounded to that point."

Unquote.

I tried exactly as what was suggested by connecting a wire between the ground connection on the rear panel of the phono stage and the ground connection also on the rear panel of the INT-60 but the hum persisted. The Maxxed Out Phono Preamp is connected to the INT-60 via both XLR and RCA cables and I switch between both via the toggle.

BTW, my turntable is a Rega RP10 with Apheta2 cartridge and the integrated amplifier I was using prior to the Pass INT-60 was the Musical Fidelity A1000 feeding into Stirling LS3/5A V2. I had absolutely no hum issue with the Maxxed Out Phono Preamp driving the MF A1000 and the pairing produces magical soundstaging and presence. I totally understand the huge gain challenges pointed out by the technical support person but there is no such issue with my 22 year old MF A1000 which is considered an outdated design compared to the INT-60.

Please let me know if you could think of anything else to resolve the issue and I really appreciate your taking interest in helping me out.

Best regards,
ELG

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