What solution do folks use for the dreaded BFD hum? - Page 32 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #311 of 330 Old 01-14-14, 05:27 PM
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Wayne

Thanks for the reply. I will give your suggestion a try and see how it works. It sounds like I should have maybe done a little more homework before giving this eq a try. I was intrigued by the possibility of using this with REW to improve on sub performance but I guess in practice there are always trade offs. I have a lot of high end equipment which without the BFD is dead quiet. As I see it it's a worthwhile experiment even if I can't find a workable solution. If after 30 days of tinkering I can't quiet this unit it'll be heading back to Parts Express. Thanks again.
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post #312 of 330 Old 01-14-14, 06:18 PM
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Re: What solution do folks use for the dreaded BFD hum?


It’ll cost a bit more than the BFD, but the Yamaha YDP2006 digital parametric EQ is dead silent. The drawback is that they are a vintage product and you can only get them used. See here for a quasi-review.

Regards,
Wayne



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Last edited by Wayne A. Pflughaupt; 01-15-14 at 01:02 PM.
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post #313 of 330 Old 01-15-14, 07:55 AM
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Re: What solution do folks use for the dreaded BFD hum?

Wayne,
I read through your series on gain structure this morning and while I don't pretend to understand all of the technical details I have a pretty good idea of how to go about using the BFD in my system now. I haven't tried this yet but I was planning on testing the noise performance of the BFD using the same connections mentioned in my first post, except using the -10db input setting on the BFD and dropping the gain on the Samson converter. Dropping the gain will undoubtedly limit the power of the EP4000 but frankly, at least for the subs I'm currently running should still be more than enough.


Dan

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post #314 of 330 Old 01-15-14, 01:11 PM
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Re: What solution do folks use for the dreaded BFD hum?


Quote:
Aleph30 wrote: View Post
Dropping the gain will undoubtedly limit the power of the EP4000 but frankly, at least for the subs I'm currently running should still be more than enough.
Dropping the S-Convert gain has no affect on the amp’s power output. You can simply increase the amps gain controls to compensate – that’s what they’re there for, to accommodate a wide variety of input signal levels.

Really, you probably don’t even need the S-Convert. The EP4000 can be driven to maximum power with a mere 1.23-volt input signal. Most modern receivers’ sub outputs generate way more than that. If you’re not sure if yours can, it’s easy enough to determine your output voltage – Part 7 of the gain structure article outlines an easy-to-accomplish process that anyone with a digital volt meter can do.

Regards,
Wayne



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Last edited by Wayne A. Pflughaupt; 01-15-14 at 01:50 PM.
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post #315 of 330 Old 01-21-14, 08:24 AM
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Re: What solution do folks use for the dreaded BFD hum?

For what it's worth I thought I would give a quick update on my progress in trying to solve the noise issue with the BFD. Wayne, as you suggested I removed the S-Convert and used a RCA-to-TR adapter on the input of the BFD. This didn't solve the noise issue but it was one less piece of electronics in the signal path. I still have plenty of output from my preamp/xover to drive the BFD. As a cheap experiment I built an AC box with the reverse polarity parallel N5401 diodes and a 22R parallel resistor to ground to see if I could break the ground loop. FWIW, this is the same scheme used by Nelson Pass in the A-75 amplifier I built 15 years ago. I had high hopes this would solve the problem but after trying several combinations of plugging in the AC using this box the noise was still there. What I found is after powering up everything if I touch the chassis on the BFD the noise level drops, but then comes back again intermittantly. It's not so much a hum as it is just noise. I ordered a ART DTI box today from Sweetwater Music and hope this solves the problem. In the grand scheme of things the fan noise from the EP4000 is much louder than that from the BDF, but that problem will be solved by replacing the fan with one that is quieter. I really like the ability to measure room response using REW and then send the filters to the BFD using the MIDI connection. It would be great to put the BFD before the preamp and correct the entire system but I'm concerned fidelity would suffer. Some day when I have nothing to do I might give it a try.

Dan
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post #316 of 330 Old 04-23-16, 07:18 AM
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Re: What solution do folks use for the dreaded BFD hum?

I have been living with the hum for years. Recently bought a new surge protector and was plugging all the power cords back in and decided, like Popeye, "That's all I can stands and I can't stands no more". (The cheater plug removes the hum) I want to try making the RCA to XLR plug to try and eliminate the hum. I have a male XLR connector and a Monster Bass 300 RCA Subwoofer cable that I had used before adding the BFD DSP1124P. I have stripped one end of the RCA and after looking at what's inside I am confused as to what connects (and what doesn't connect) to the XLR pins. I will attach a picture. This is a description of Monster Bass 300:

Balanced Subwoofer Cable Improves Bass Response
• More Accurate, Realistic Home Theater Bass w/ Greater Clarity
• 24k Gold Contact Straight-Cut Turbine Design Connectors
• Special Low Frequency Wire Network Delivers Deeper, Tighter Bass
• 12 Ft Length

Any help would be appreciated.
Thanks in advance
Ron
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post #317 of 330 Old 04-23-16, 01:37 PM
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Re: What solution do folks use for the dreaded BFD hum?


Basically there are only two functioning connections from the RCA: The signal (+), which appears at the connector tip, and the signal (-), which appears at the connector sleeve.

You’ll need an ohm meter to determine where all the wires are showing up on the connector. I expect that the two insulated wires have continuity with the RCA tip, and the two bare wires with the RCA sleeve. However, it’s possible that only one of the insulated wires is actually connected to the tip, ditto with the bare wires and the sleeve.

As far as the XLR connections, the signal (+) will go to Pin 2 and signal (-) to Pin 3, with a jumper to Pin 1. If the hum and noise persists, try disconnecting the jumper.

Regards,
Wayne




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post #318 of 330 Old 04-23-16, 04:14 PM
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Re: What solution do folks use for the dreaded BFD hum?

Hello Wayne.
Had to run out to the hardware store to get a new multimeter as the one I had has died. Had to watch a short you tube video to get up to snuff on using it as I have never really used it much.
The brown wire goes to the tip by itself. The black, bare silver, and the ground shield are all connected to the sleeve.
So, does this mean that all 3 of the sleeve connecting wires need to go to Pin 3?
Just so you know, my understanding of this kind of stuff is limited!
Thanks,
Ron
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post #319 of 330 Old 04-23-16, 05:37 PM
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Re: What solution do folks use for the dreaded BFD hum?


Quote:
So, does this mean that all 3 of the sleeve connecting wires need to go to Pin 3?
Yes. You might want to trim out a good portion of the strands of the copper shield wire to make it all fit the XLR. BTW, you can find soldering tips in my article on making your own cables. Link in my signature.

Regards,
Wayne




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post #320 of 330 Old 04-23-16, 07:16 PM
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Re: What solution do folks use for the dreaded BFD hum?

Wayne,
I have tried with and without the jumper. The hum is still present. I plugged the cheater in as test, and the hum goes away 100%. I had read through all the posts where the cause of the hum is solely from the BFD and the cheater plug stops it cold. (True for my case) I thought part of this fix was to "leave the ground/shield open". (Page 7 post 68 from Bobqspr). I don't really know what that means but what I have done is connect everything from the RCA to the XLR. Am I supposed to leave somethings unconnected? I have the cheater plug in right now listening to some Pandora and it is so much better without that dag gum hum!
I realize this is a really old topic for everyone but I'm hoping for a solution. Sorry for bringing back such a difficult topic!
Thanks
Ron
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