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Balanced Outputs.

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I am installing XLRs on my DIY 4 channel amp that has 2 Icepower stereo amp modules in it. Would I just solder the 3rd wire to the ground pin on the XLR jack in the DIY amp?

 

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On January 11, 2020 at 8:44 PM, Ron E said:

I am installing XLRs on my DIY 4 channel amp that has 2 Icepower stereo amp modules in it. Would I just solder the 3rd wire to the ground pin on the XLR jack in the DIY amp?

 

I believe so.  As long as each channel has HOT (+) and COLD (-) connections to the respective XLR pins, the shield wire can, indeed should, connect to ground.  It is critical that the left and right COLD (-) connections are kept discrete, as opposed to sharing a common ground as in a single ended connection.

 

As I type this, I’m enjoying Diana Krall’s Live In Paris in balanced mode from a Pono player into a DIY TPA3255EVM class-D chip amp driving DIY “Supers” and into a pair of balanced iNuke1000dsp amps, each powering a pair of DIY Exodus Anarchy TH subs.  In my small basement space the result is glorious.

 

The first photo shows cables I made to connect the Pono’s two 1/8” TRS outputs to another balanced class-D chip amp via RCA connectors. In that case, the HOT and COLD of each channel connect to the pins of RCA connectors.  The RCA collars are connected to the shield wires.  Keeping the COLD (-) connections discrete necessitates two RCA connections for each channel.

 

5a24abbb23730_20171203_201027(Medium).thumb.jpg.49ef2364df84450ab33ca58f7ec9f754.jpg

 

The second photo shows balanced connections from a Pono player through modified Monoprice XLR balanced cables.  The XLR connectors were removed from one end and replaced by 1/8” TRS plugs.  The HOT of each channel to the tips, the COLD of each channel to the rings, and the shields to the sleeves and to ground.  The remaining XLR plugs connect to corresponding XLR connectors in the front (to the left) of the case that now houses the chip amp.  The balanced signals pass through the case to be fed, still balanced, to the pair of iNuke sub amps by unmodified Monoprice XLR cables.

 

The braided shielding shown is grounded.  It was probably unnecessary for the short runs inside the case, but I had it available and it couldn’t hurt. 

 

A Pono player is sitting on the Mean Well 48v power supply.  Also in the photo, at the top, is another class-D chip amp connected to another Pono player in balanced mode by DIY cables with a pair of 1/8” TRS plugs and four RCA connectors.

 

TPA3225EVM.thumb.jpg.f97482699864649f59c534ceac680069.jpg

 

In the above photo, the two connectors toward the top of the case, with red shrink tubing, are Neutrik Speakon outputs to the Supers.  The two connectors closer to the Mean Well are Neutrik XLR connectors passing the Pono’s balanced output to the pair of iNuke sub amps.  The iNukes’ dsp controls the signals sent to the subs.

 

A4751B20-D2E1-4EA5-AAA8-3C892909EE70.thumb.jpeg.56e3ca4ad7a70a2cec193dda6fc8c989.jpeg

 

FWIW, the yellow Pono player seems to have died.  The two black players are alive and well.  I see that NIB Pono players are available on eBay for less than $200.  I guess I’ll buy one as a backup.

 

Despite it’s many faults, the excellent ESS Sabre DAC and balanced output make a Pono player the perfect pre-amp for my chip amps.  I doubt I can replace them for less than $500 with anything nearly as good.

 

3DC07EDB-7290-4EDF-A698-E54496654C8E.png

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I'm using balanced connectors from my pre-pro to my amp.  Everything into the pre-pro is rca or digital.

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So I can run balanced from my Xilica to my amps which are not balanced, but will have XLRs because I prefer them, correct? What do I run the ground terminal on the XLR jack to for ground...amp chassis?

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7 hours ago, Ron E said:

So I can run balanced from my Xilica to my amps which are not balanced, but will have XLRs because I prefer them, correct? What do I run the ground terminal on the XLR jack to for ground...amp chassis?

 

It's not clear to me what you're contemplating.  People often refer to any XLR cable as  "balanced" when they are not actually referring to a balanced (B) circuit.   The whole process was counterintuitive to me.  It took several diagrams and much advice from those more knowledgable than I before I was comfortable connecting a B Pono player to a B amp.  The TPA 3118 "Wiener" amp with four RCA inputs is converted to single ended (SE) by inserting regular SE RCA cables into two of the four RCA jacks and inserting shorting plugs in the empty RCA jacks.  Converting the TPA3255EVM to SE requires the removal of jumpers on the board.  I have always connected SE to SE or B to B never B to SE or SE to B.  Watch out for white smoke.

 

It sounds like you want to run a B output to a SE amp.  I'm reasonably certain it can be done, but I'm absolutely certain I'm not the one to tell you how to do it.  I would start with Xilica for advice.

 

I found the following informative, but I still wouldn’t presume to tell you how to connect a B output to a SE input.  I’m pretty certain a transformer is needed.  I’m also certain that it cannot safely be done with cables and connectors alone.

 

https://crookwood.com/blog/dealing-with-unbalanced-gear-in-the-studio/

 

Perhaps Rich @rhing can chime in.  He knows about such things.

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Thanks,I know there areconvertors that will convery from balanced to unbalanced, and I believe also the other way... I just would prefer not to have to add another external device, and I cannot afford to buy
4 balanced amp modules for the horns when I have enough unbalanced modules for the job. I could always get 2 minidsp 2x4s, but I prefer to run Xilicas.

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1 minute ago, Ron E said:

I just would prefer not to have to add another external device, and I cannot afford to buy

 

 I understand, but can you afford the smoke?

 

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Could I just not hook up the amp to the ground wire jack on the inside of the amp since it is not a balanced amp module? Amp is a Icepower 50wpc stereo amp module.

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1 minute ago, Ron E said:

Could I just not hook up the amp to the ground wire jack on the inside of the amp since it is not a balanced amp module? Amp is a Icepower 50wpc stereo amp module.

 

I don’t know, so I can’t make a recommendation.  Perhaps someone else does and can.

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A lot of circuits with an xlr input or output, can run unbalanced simply by connecting pin 1 (ground), to pin 3 (negative).  However, a transformer will help you do that safely so you don't let out the magic smoke. Good transformers aren't cheap. I would start with Jensen, first.

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@Ron E what ICEpower amp(s) are you using? I thought their amp modules were balanced in. I am in the beginning of designing and building an amp using their modules also.  

If it is in fact an unbalanced input you can take the pin 3 from the Xilica and run it to the ground input on the amp module(through pin 3 of the XLR you are installing) Pin 1 of the XLR you are installing should go directly to the chassis.

Google "Pin 1 problem".

 

ICEpower 50ASX2SE

Is this the one? I do indeed see it is single ended(not balanced) input. The input connector has two signal ground connections one for each channels input signal. These ground inputs are where the pin 3 of the XLR should go.

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[mention=55367]Ron E[/mention] what ICEpower amp(s) are you using? I thought their amp modules were balanced in. I am in the beginning of designing and building an amp using their modules also.   If it is in fact an unbalanced input you can take the pin 3 from the Xilica and run it to the ground input on the amp module(through pin 3 of the XLR you are installing) Pin 1 of the XLR you are installing should go directly to the chassis.

Google "Pin 1 problem".

 

Thanks, I have the 50asx2, and I have 3 of the 50asx2btls too. The btl versions are balanced in, but the other ones are single ended only. I have read about modding them,but I have not seen where anyone can verify that it works properly. Some of the people are saying they get hum or that it sounds very bad. 

I am a little confused... pin 3 goes to ground, and pin 1 goes to chassis ground. Shouldn't only one pin be going to the chassi ground, and the other 2 go to the amp module, or is pin 3 going to the negative of the rca, and pin 2 to the positive rca? The amp modules have rcas on them, and when we used them as unbalanced before we cut the rca cables to hook up to the rca jacsk... so this should be pretty easy once I k ow the way to wire it.

 

So e people are saying it could burn up without a transformer...if so would it damage the icepower amp or the xilica crossover?

 

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You will not damage either. Pin 2 of XLR goes to signal in, pin 3 goes to that signal's ground and pin 1 of the XLR goes directly to the chassis. Does this make sense to you?

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Got it, thanks!

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14 hours ago, Ron E said:

So e people are saying it could burn up without a transformer.

 

Not what I said, it all depends on the equipment.

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To guarantee having a functioning Pono player for the foreseeable future,  I recently sniped a bid on eBay and got a black NIB Pono for under $200, including sales tax and delivery.  Now I can continue to feed a balanced diet to my class-D chip amps.

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The player arrived yesterday in its wooden box inside sealed original packaging.  Although I intend to set it aside as a spare, I charged it up and confirmed operation.  Now I’m set for life.

 

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On 1/9/2020 at 4:09 PM, babadono said:

^what he said.

As long as the balanced output DOES NOT have an active signal on pin 3.

The picture shown is not for a balanced output to a single ended input. It is for a single ended output to a balanced input. XLRM connectors plug into balanced inputs.

 

If the equipment uses servo balanced outputs pin 3 can be grounded without equipment damage, or left unconnected. Behringer and DBX, among others, use servo balanced outputs. Outputs that are not servo balanced may need a resistor on pin 3 to ground, with the signal connected to pin 2. 

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