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Thread: Consumer and Pro-audio electronics: Connectivity

  1. #31
    Senior Señor boputnam's Avatar
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    Addendum...

    Two things:

    Rane makes a thingy called Balance Buddy: Rane Balance Buddy which by description sounds like the perfect device. It DID NOT work for me. It apparently does not isolate the Pin1 / shield from the chassis - so when rack mounted this bad boy GL's bad.

    Radial has a newbie: Radial Twin-Iso that has the right idea. There isn't much on this on the Radial site - only that press release. Maybe Oldmics has some experience with these... I'm presently employing Radial's JDI in these same positions and it works superb, but is over-engineered for this application.
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    bo

    "Indeed, not!!"

  2. #32
    SteveW
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    Balanced power - It worked for me!

    I struggled with all the interconnect issues for years. When rigging up some 50 pcs. of gear things get interesting real quick. You get something optimized and it all starts over as soon as you repatch. The tool kit included Jensen tranformers, Balance buddys and the like, Tascam LA's, wood racks, lifts, aux chassis grounds, star grounds, cable tricks of all sorts - it keeps going, along with a zillion if's, ands, or but's.....
    The fix: one Equitech balanced power supply. All the AC grounds and signal grounds (unbalanced too) are directly referenced the center tap of an isolation transformer that is referenced to earth ground. Neutral and hot become +60v and -60v (out of phase). Interconnect schemes are WAY easier to deal with. The 60 Hz. issues are gone along with audible noise floor.
    Soapbox statement: The whole problem starts with unbalanced power, and the only way to eliminate all the resultant problems is to balance it.
    You still have to deal with +4/-10 issues but that's easy. Not to sound like an Equitech rep, Furman sell these things too. A good explanation of why this works can be found at www.equitech.com
    These things will cure everybodys headaches (heartaches?) except for maybe Bo's.

  3. #33
    RIP 2010 scott fitlin's Avatar
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    Steve

    For years now, I have been looking at EquiTechs boxes! I have been told by a few who do electrical work for recording studios it works, and its ( balanced AC ) is also supposed to sound better. Not just lower noise, but also better sound.

    What are your findings, besides getting rid of GL,s and lowering your noise floor?

    EquiTech makes nice, big commercial boxes for people like me!

  4. #34
    Senior Señor boputnam's Avatar
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    Hey, Steve...

    Thanks for the referral, and testimonial. Sounds like the proper solution. I actually saw a few one of these in the racks of Charlie Daniels' Band at the Grand National Rodeo on Friday.

    Got a source for them?
    bo

    "Indeed, not!!"

  5. #35
    SteveW
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    Scott

    I bought the rack mount 5Q model. 40 amps continuous. Got it with the OFC and meter option. Also got an upgrade (not referred to on their site) that gets you a bigger transformer for more headroom and cleaner power yet. That gets you about 50 amps worth. It added another rack space to the height of std unit too. Wall mount versions are functionally the same. Didn't go that way cause I could get the juice needed in a rack version and be able to move it if desired. That was the plan anyway, but not anytime soon..... it took two guys just to lift it off the ground, and four to raise it up high enough to stick it in the wall. Some of the outlets on the back are filtered (HF) for power amp feeds too. It indeed does all the things they say it does.
    If your starting with a complex and/or poorly grounded system to begin with it would do wonders. Benefits realized obviously depend on the system complexity and ones ability to address issues. Some lucky guys with playback only systems might get away with just proper attn. to grounding and be happy. I started with a system in a control room that had every worthwhile band-aid know to man applied - starting with isolated power grounds at same lengths....all that stuff. Everytime you get another toy, the first thing you gotta do is figure out which one of 14 ways of interconnect your gonna try first. Not having to do that bit anymore is better than a recording that mixes itself.

    My observations: Started with all as it was. Then fed entire system with balanced power. Console and amps on '10' was same noise floor as it used to be on '5'. Started pulling bandaids one by one. Before balanced, doing this just increased noise. Balanced, it only got quieter. After optimising the grounding for balanced power, which was more fun than it should be - I could barely hear the noise floor when full up. Gear was Neotek series 2 to bridged Crown K1's to JBL 4435's (the ones Giskard is fixing - because the noise floor was so low I didn't know it was full up).
    They make some audiophile stuff too, but that may be for those folks that feel the need.....

  6. #36
    SteveW
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    Bo...

    Sorry, can't help with source. Got mine through a one man Internet gear house called Calipso music over a year ago. I searched and came up empty.... like as if he's gone away. No wonder, he sold me the unit for 2800.00. The guy said his markup was something like 50 bucks. Equitech drop-shipped it to me. They (Equitech) said they would sell to me direct, but wanted about a grand more than this guy did. At the time I was just window shopping, wasn't really convinced yet - it seemed like a good idea but was leary about the value-add thing in regards to the overall scheme of things. Couldn't pass on the deal, took the chance and gee wiz... it paid off (for once). Good at twice the price!

  7. #37
    Alex Lancaster
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    Smile

    Hi:

    Apparantly it is a 6 KVA isolation, center tapped transformer, what else does it have?

  8. #38
    SteveW
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    Ummmm....well, it's not an Isolation tranformer if that's what you mean. It does not supply a regulated voltage either. The unit I have is fed 240 V. If regulated final supply is desired then you need to feed the unit with an 'isolation transformer' that does just that. Personally, I don't care if my voltage swings from 118 to 122 V. If your question is in regard to what it has that's different than an iso transformer - that's easy.... Iso doesn't provide balanced power. Equitechs web site is chuck full of the particulars.

  9. #39
    Senior Señor boputnam's Avatar
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    Important caveat

    As I now better understand it, these balanced power supplies must be used in complete power isolation - that is, if your system incorporates, say, audio from a TV with cable or PC with modem, you're toast. The cable and modem open to different ground source(s), and the balanced power supply cannot be used.

    Hopeful I was - wiser I am...
    bo

    "Indeed, not!!"

  10. #40
    jkc
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    Isolate

    For those of us in countries with 230 Volts where lifting the ground is a definite no no mains isolating transformers seem to do the trick. I have 5 of them stashed under the house with the amps.

    The transformer laminations can hum and buzz away to their hearts content and keep the noisy amp fans company.

    The 9 amps stashed in the basement make quite a racket even before they start pushing electrons up to the speakers.

    It is also possible to lift the amp circuit boards from ground with a resistor or diodes if you know what you are up to and the amp case can still be at ground for safety’s sake.

    I recently was able to cure hum bars on my TV by making the power cable and video cables the exact same 10 meter length, works on the theory that the very small current flow is equal in all cables so no “loop”

    However something must be a bit loopy when you have 10 Kw’s driving a JBL surround system.

  11. #41
    Trying to be nice Infredible's Avatar
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    Nasty hum

    Quote Originally Posted by boputnam
    Surfing the most interesting "Describe your HIFI System" sub-forum, and based upon some pm's I received from it, it occurred to me many of us are encountering the same problem: 60Hz hum from connecting consumer gear to pro audio.

    Consumer gear is not grounded - it persistently has only the two-pronged plug, fat on one ear (for polarity purposes). Hooking audio outs from a consumer preamp, amp, etc. to pro audio gear (EQ, amp, etc.) typically results in a nasty 60Hz hum. VERY simply speaking, that hum is caused by the consumer gear "seeing" another possible ground path, and trying to ground through the pro audio gear.

    I use two solutions:

    First, and best, is a DI - Direct Injection box. These have "ground lift" switches, which alleviate the problem.

    Whirlwind makes a great stereo model (the Direct2) which has 1/4" unbalanced inputs/bypass and balanced Lo-Z XLR outs. The added benefit of the DI is it converts the connections to XLR, which all pro audio gear takes. Come out of the DI with a short mic cord into the pro gear. Go into the DI from your consumer gear with a lead that converts RCA's to 1/4" unbalanced. Monster Cable makes some nice (and pricy...) ones.

    Checking the Whirlwind site yesterday, I found they're now offering a VERY nifty DI (the "pcDI") that accepts 3.5mm (1/8") mini TRS plug AND RCA's in TWO SEPERATE INPUT SIGNALS in one DI. So cool. The mini would connect your PC to the consumer gear, and whipe out that hum! As well, you can use the RCA's, too. Check it out: http://www.whirlwindusa.com/dirbox.html

    Whirlwind by email confirmed that FirstAudioUsa (http://www.firstaudiousa.com/page1.html) is a reputable dealer (I Googled to them...). I ordered some through [email protected] who has an "eBayStore" that hosts competitively priced Whirlwind gear.

    Second - and a nearly as good cheaper alternative - is an odd little lead that Radio Shack makes. The "Audio System Ground Loop Isolator" - Part No. 270-054 http://www.radioshack.com/product.as...5Fid=270%2D054
    This uses inductive coupling for the audio signal, so the interconnected gear cannot seek ground across them. The lead is RCA-to-RCA, so may keep your wiring needs simple (for now...). There is slight signal loss, but it is not anathema to the solution.

    Hope this helps.
    email with questions
    Hi Bo,

    Last sunday I got my satellite system installed and of course since then I have a nasty ground loop hum that I can't get ride off.
    I was reading you recommandations in the above thread and was wondering about something. I'll describe my system connection:
    Everything is consumer gear except my EQ which uses XLR in and XLR out. My receiver has only a two prong plug. I was thinking about ordering the pcDI which looks like a good solution. But here's is my question. My receiver is a big Yamaha which has a preOut/mainIn that output the preamp signal for external amplification and the mainIn to use the internal amplification from another external source. So I insert my EQ in the the preOut/mainIn loop and everything gets EQed. If I insert a pcDI in between PreOut and EQ in will it work? Since the EQ out goes back to the receiver for amplification. I guess the ground will still seek is way toward the EQ?
    Hope you get the picture.

    Fred.

  12. #42
    Trying to be nice Infredible's Avatar
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    Ok, a trip to RadioShack just solved the problem. I plugged the EQ to the amp with a ground lift prong and an isolation transformer in between the amp and EQ just cleaned the signal to a 0 background noise. Thanks Bo!

    Fred.

  13. #43
    Senior Member Don Mascali's Avatar
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    The Cable TV isolation transformers work but not for Broadband signals. I have Comcast Digital TV and a cable modem. I lost the DTV signal strength and quality with the inline isolation types at the converter. The internet connection also causes problems with my PC connected to the audio gear. My CATV tech friends tell me most of it comes from the signal amplifiers up the line having a different ground potential than at the house.

    My solution was to go outside and drive a ground rod halfway between the cable and the power entrance and bond all three stakes together with 6 ga copper wire using NoOx compound on all connections. It has been the best so far, but still not perfect.

    If I unplug the cable all of my stuff sounds great. I use a wide range of Pro and consumer and a lot of it is that lowly regarded Behringer stuff.
    4406, 4412A, L100, L100t3 (3 pair), L1, L7, 4645C, 4660A, 4695B, SR4735 and various DIY JBL Pro loaded systems.

  14. #44
    Senior Señor boputnam's Avatar
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    Quote Originally Posted by Infredible
    I plugged the EQ to the amp with a ground lift prong and an isolation transformer in between the amp and EQ
    Hey, Fred...

    Try this without "floating" the EQ ground. What you're doing is not as bad as floating the ground on an amp, but if you can avoid it is better. The isolation transformer alone should be enough (unless there's another source of GL).

    You did not have a GL until the satellite, right? How is the satellite connected to the Yamaha - RCA's (single end'ers)? If so, that is where the isolation transformer needs go - between the satellite and the amp.
    bo

    "Indeed, not!!"

  15. #45
    Senior Señor boputnam's Avatar
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    Quote Originally Posted by Don Mascali
    My CATV tech friends tell me most of it comes from the signal amplifiers up the line having a different ground potential than at the house.

    My solution was to go outside and drive a ground rod halfway between the cable and the power entrance and bond all three stakes together with 6 ga copper wire using NoOx compound on all connections. It has been the best so far, but still not perfect.
    Don...

    Try peeling-back the shield on the coax, preventing it from connecting to the preamp input. I only use the signal lead, and the hum "left the building". Your friends are at-least partially right - grab a volt meter and measure across the shield and signal wire - you will be astounded at what is travelling that coax...

    ---------------------------------

    And, Don - I'm sorry for beating you up on the Behringer boxes. They are wonderfully priced, but realize that at those price points reverse engineering alone will not afford the top-quality filters that make for good, audiophile listening. That was my point. I was paying your acoustic tastes a compliment and suggesting you move-up the cost curve a bit - you will be rewarded.
    bo

    "Indeed, not!!"

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