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XLR output to RCA input done properly?

Ricardus

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There are DI boxes that is differential that compatible with differential incoming signal. Differential ops am in these DI. It is just like adding differential input for your amp that don't include one.
What commercial DI boxes have opamps? The three most popular I can think of are the Countryman, Radial, and the Neve. These are all FET amplifier circuits with no opamps.
 

kongwee

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What commercial DI boxes have opamps? The three most popular I can think of are the Countryman, Radial, and the Neve. These are all FET amplifier circuits with no opamps.
ART CLEAN Box Pro. They have single line circuit to look at and make sure it is differential. I don't know about other brand. FET is only part of differential circuit. Opamp is just an integrated IC chip. Transistor, LCR in one package.
 

Ricardus

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That's a slightly different animal because it doesn't have a 1/4 inch input for guitar for keyboards. It's a box specifically designed for DJs or something to convert to balanced.

For example I work in recording studios and have built 9 DIs and none of them have RCA inputs or opamps.

But what's the point here anyway? I'm not advocating for DIs. I'm advocating for a solution using THAT chips.
 
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SoundOfMind

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I don't know how much gain will be passed through the circuit, but having more than 5 volts might be wise just so you don't hit the rails. When I build my THAT box, I'll be using +15/-15 just to have the headroom.
The Mean Well RD-3513 has +/- 13.5V, although it would require mounting in a box. Should be fine for the purpose. It's $17.10 at Jameco.
 

Prometeo

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If I want to connect my DAC's XLR output to a preamp or integrated amp's RCA input, what are my options?

This Emotiva adapter cable seems to do it "properly" https://emotiva.com/products/balanced-xlr-female-to-unbalanced-rca-female-adapter-interconnect but it'd be nice to have a cable wired the same way but with a male RCA end to avoid more connections then necessary. Does anyone know of any? (or perhaps someone who could wire a custom cable this way?)

I'm also seeing people talk about using a "1:1 transformer" to do the conversion? https://www.superbestaudiofriends.o...le-ended-converter-xlr-to-rca-bal-to-se.9506/

Not sure what to make of all this and which way to go.. your insight would be much appreciated, thanks!
One late question:
Does your DAC also has RCA outputs? What model is it?
 
OP
OP1M.DR3M

OP1M.DR3M

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One late question:
Does your DAC also has RCA outputs? What model is it?
It's somewhat of a theoretical question but yes it has rca outputs.. currently Schiit Modius but considering Schiit Bifrost 2, Denafrips Ares 2, or SMSL VMV D1SE next
 

Prometeo

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It's somewhat of a theoretical question but yes it has rca outputs.. currently Schiit Modius but considering Schiit Bifrost 2, Denafrips Ares 2, or SMSL VMV D1SE next
In accordance of everyone giving you good advice on how to pass from XLR to RCA, there is the underlined question. Are you interested in sound quality? Or just to have a “sounding” connection? Once in analog domain every process in the chain distorts the final sound.
I have a I2S Roon endpoint to my DAC then real Full XLR from my DAC’s internal class A preamp to the XLR inputs of the amplifiers, and then to the speakers.
All 100% balanced. No middle preamp. No RCA’s - (I’m talking “religion” here, so I respect yours)
I recommend: Use your DAC’s RCA Outputs and a AB Switch box to connect the other stuff, or use a pizza cable. This is not a sarcastic answer, I use this myself as I have another parallel system with a higher WAF (Wife acceptance factor).
If the trend is to continue your original path as the only system in place, I will recommend and active conversion.
Also, I will add two brands to your DAC list: original West Lake M-DAC and Topping 90SE.
 

rdenney

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I built an interface to go from an unbalanced RCA output on my preamp to a balanced input on my power amp. I was using an adapter cable before, and near as I can tell it worked fine.

But I'm pondering adding a MiniDSP Flex inline between the preamp and the power amp, and if I'm going to spend hundreds I want it to have balanced connections--I see that as the long-term endpoint for the stuff that I buy.

My preamp came with the option to have balance outputs, but I've never seen that particular preamp (a B&K MC-101) with the balanced optional output actually installed, and I can't find schematics to identify just how they did it. And maybe I do recall somebody's off-the-cuff comment that their balanced output wasn't all that well implemented, even though their amps also have balanced inputs.

I originally thought to build something inside the preamp enclosure, but couldn't find power that would work and didn't want to put a transformer inside a preamp whose main transformer is in a separate box. So, I ended up building a separate enclosure.

So, I bought a couple of the Sparkfun Outsmarts modules that use the THAT 1646 differential amplifiers, and a Meanwell +/- 15VDC power supply, and installed them in an enclosure:

Outsmart-front.JPEG


Outsmart-inside.JPEG


The balanced output uses a TRS quarter-inch phone plug, and I bought cables with that plug on one end and an XLR on the other end to go to my amp. The ones I bought were too short--ideally I'll like to use very short RCA cables on the preamp end and longer balanced cables to get from there to the amp.

The Outsmarts takes the unbalanced signal and reamplifies it with reversed polarity to create the other side of the balance pair. Thus, it provides 6 dB of gain--twice the voltage swing compared to the unbalanced input. It's quite clean for use with vintage equipment, but it someone is wanting a dac with a SINAD of 115 or more dB to go into an amp with a SINAD that high, this device will bring it down to something around 100. Still effectively transparent to my ears, and still better than my old analog preamp. Still better than the CD's I listen to. So, not much of a compromise. But if that is intolerable, buy a DAC with properly implemented balanced outputs and forget this stuff.

As to what I can hear, the only effect that is apparent to me is the gain, and even that is a subtle effect. Playing the highly dynamic drum solo on the Chesky demonstration CD, I can still make the clipping indicators on my Buckeye NC502MP amp flash, but not quite as often and not quite as brightly (meaning: duration not as long). I cannot hear any audible clipping even when those indicators are flashing on the transient peaks, so I can assume they are fairly conservative.

I used the 15-VDC bipolar power supply because the THAT chip's voltage swing is limited to a range about 2 Volts less on each end as the rail voltage. So, that power supply gives me +/- 13 volts on the chip's output. That exceeds the "maximum" output voltage of my preamp (which is 12 volts, unbalanced). It vastly exceeds the input sensitivity of the amp, but I may not always use an amp with 26 dB of gain.

In practice, I can more often use the line-amp bypass feature of my B&K preamp. Even vintage analog sources that output, say, 500 mV instead of the 2 full volts a typical CD player will produce can drive the power amp to loud levels. That was not always the case before.

The only weird thing is that the Sparkfun modules will hiss on their outputs if their inputs are floating and undriven. My preamp doesn't have an on-off button, but rather uses a switch to change the output from the line output to the headphone output. "Off" is in the headphone output position. If the power amp is on, the hiss is objectionably loud. It vanishes when I switch the preamp so that the unbalanced input is being held to nominally zero volts instead of floating.

Unlike a DI box, these do not have extraneous controls--no volume control or anything like that. And they do not have musical-instrument preamplifiers in them that have to be attenuated, as would usually be the case with a DI box.

Rick "who will probably build more of these--they are handy" Denney
 

Ricardus

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I've got PCBs that do the same thing as those Outsmarts boards. For balanced input and balanced output, all using the THAT chips. That is if anyone wnats to build their own. I'm building a box right now and will be using the identical PSU. I have an additional filtering board I'll add as well.
 

Ricardus

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Unlike a DI box, these do not have extraneous controls--no volume control or anything like that. And they do not have musical-instrument preamplifiers in them that have to be attenuated, as would usually be the case with a DI box.
Which DI's have you used that have volume controls? I'm just curious?
 

rdenney

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Which DI's have you used that have volume controls? I'm just curious?
All of them that I see, either passive or active, provide a pad of some sort, either fixed or variable, in the -3 to -30 dB range, give or take. Some provide gain; others don't. All of them that I see use transformers to make the match, which will have consequences. All of them are designed to be plugged into microphone inputs on mixer boards (read: very low level) and the active ones seem to get their power from the mixer's phantom power. Of course, they are designed primarily for plugging electric guitars into mixer boards, and the guitars themselves have a gain control, and so does the mixer board. But the pad helps prevent overdriving the mixer input.

In our application, the upstream device may or may not have output attenuation, and the downstream device may or may not have input attenuation. Of course, one or the other of them will have some kind of attenuation or gain control. But that's why I powered mine enough to fully accommodate any potential stereo preamp.

None of the instrument DI boxes seem to me really purpose-built for use in matching unbalanced to balanced line-level stereo equipment.

Rick "the THAT modules seem to have 15-20 dB higher SINAD, too" Denney
 

Ricardus

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All of them that I see, either passive or active, provide a pad of some sort, either fixed or variable, in the -3 to -30 dB range, give or take. Some provide gain; others don't. All of them that I see use transformers to make the match, which will have consequences. All of them are designed to be plugged into microphone inputs on mixer boards (read: very low level) and the active ones seem to get their power from the mixer's phantom power. Of course, they are designed primarily for plugging electric guitars into mixer boards, and the guitars themselves have a gain control, and so does the mixer board. But the pad helps prevent overdriving the mixer input.

In our application, the upstream device may or may not have output attenuation, and the downstream device may or may not have input attenuation. Of course, one or the other of them will have some kind of attenuation or gain control. But that's why I powered mine enough to fully accommodate any potential stereo preamp.

None of the instrument DI boxes seem to me really purpose-built for use in matching unbalanced to balanced line-level stereo equipment.

Rick "the THAT modules seem to have 15-20 dB higher SINAD, too" Denney

I just built 9 DIs, and only two have pads.
 
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rdenney

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I just built 9 DIs, and only two have pads.
Great. I was going off the dozen or so Sweetwater sells.

Rick “none of which I’d particularly want in a home stereo” Denney
 

ADU

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This is slightly OT, and may be a dumb question. But I'm just sort of curious how the balanced XLR outputs on the Schiit Modius would be different that the XLR outputs on a pro audio mixing board. Wouldn't they both be designed to output a +4 dBU line level signal?
 

ADU

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It's somewhat of a theoretical question but yes it has rca outputs.. currently Schiit Modius but considering Schiit Bifrost 2, Denafrips Ares 2, or SMSL VMV D1SE next

If you don't mind me asking, what are you currently using the Modius RCA outputs for?
 

Ricardus

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This is slightly OT, and may be a dumb question. But I'm just sort of curious how the balanced XLR outputs on the Schiit Modius would be different that the XLR outputs on a pro audio mixing board. Wouldn't they both be designed to output a +4 dBU line level signal?
They should be.
 
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ADU

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They should be.

Thank you, Ricardus.

I assume that the XLR outputs on the Modius are fixed level, and designed to interface with the XLR line level inputs on a balanced headphone amp, like the Schiit Magnius. But would they also be usable in a variable mode to connect to a pair of powered monitors, and adjust their volume?

I'm just trying to understand some of the connection options on the OP's gear a little better, to see if there may be some better solutions than what he's currently trying to do. And to that end, it might also be helpful to know how the Modius's RCA's are currently being used.
 
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ADU

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Based on a closer look at the specs and some reviews on both the Modius and the Magnius, it appears that there is no volume control on the Modius. So I guess its output is fixed on both RCA and XLR. And it looks like it would have to be connected to something like the Magnius to be used as a preamp and volume control for some powered speakers.
 

ADU

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This will probably already be obvious to most here. But generally speaking, you don't want to try to connect a balanced +4 dBU line level XLR output to an unbalanced -10 dBV RCA input (or vice-versa) because the cables, pins and signals are different, and not really compatible without some conversion or transformation. So it's generally easier to simply rearrange a few components to avoid having to do this... At least in home audio.

This kind of conversion is fairly trivial though in pro audio. And can be accomplished with just about any halfway decent mixing board. I assume that people are looking for or suggesting other options though because they think a mixer wouldn't deliver good enough sound quality. Or because they think it would not be a good fit with their other home audio gear.

There are some other ways to accomplish this with products like the ones below from Radial. But they are a little on the expensive side. Which is why it's usually better, and also more cost effective, just to rejigger your other gear a bit to simply avoid the problem.



The Radial J+4 is designed to convert -10 dBV consumer line level to +4 dBU pro line level. While the J-Iso goes the other direction. And both are in the $250-300 range. (If you want quality components, like the Jensen transformers in the J-Iso, I guess you need to pay for it!) Rolls or ART may also make something similar. But I think the two Radial products above may be best for something like this, if you really need dedicated boxes to perform the conversion.

Fwiw, the Bellari HA543 headphone amp (made by Rolls) that I'm using was only $100. And it can accept either balanced XLR line level inputs (like the Schiit Magnius), or unbalanced RCA line level inputs. The outputs on it are not balanced though. So it is not balanced all the way through.

Using a headamp with balanced +4 dBU XLR inputs (like the Magnius or HA543) could potentially free up the RCAs on the Modius for something else though, if that's really what you want.
 
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