XLR VS 1/4 TRS...have you noticed?

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philboy

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I always thought there was no difference between XLR connectors and 1/4 TRS (NOT stereo... but BALANCED) connectors...

Doing some tests with my new Presonus Eureka preamp i noticed i'm loosing at least 15dB when using the 1/4 balanced TRS output to the 1/4 Balanced inputs of my mixer (instead of using XLR to XLR). Then i figured i could try with a special nutrik cable: XLR (from pre) to 1/4 TRS studio cable (to mixer) : still -15 dB. A bit confused, i tried with an ordinary 1/4 guitar mono cable from pre to mixer : still -15, no difference with the balanced 1/4 TRS... Seems that no matter where i put a 1/4 connector (weather balanced or unbalanced) in the chain i loose 15dB. The difference if huge very audible.

I thought it might be the mixer inputs so i tried in all the other inputs (total of 8) with the same results. Then i gave a try and hooked directly in my DELTA66 soundcard, and again the same thing. Then i thought it might be the preamp itself, so i hooked up with the same configurations in my three other preamps (A RP220, A Joemeek and a Focusrite), re-did all the tests and the results were exactly the same.

Please note that although i'm not an expert, i'm using proper cables and i'm not confusing "stereo 1/4" cables with balanced 1/4 TRS cables. Also i tried with various cables making sure there was no problem with the cable itself...

This makes me conclude that whenever you're using 1/4 connectors, weather it's unbalanced (TS) or balanced (TRS) you're loosing 15 dB compared to a direct XLR to XLR. Is this normal? Althought you might be able to run longer cables with Balanced 1/4 TRS instead of mono ones, i'm rather surprised of this gain loss. Any comments? (just trying to understand...)

Maybe someone better informed could explain?

Thanks for reading!

Kind regards

Phil
 
Sounds like something else is going on here... XLR & TRS connection, although mechanically different are electronically identical... and 15 db loss is better than double what you would expect if you were somehow going from balanced to unbalanced.

Any input sensitivity switches you're missing?
 
Hello evryone and thanks for replying. No hyped trims, input pads /eqs/ switched on on the mixer, as i have carefully triple-checked the signal path from A to Z... As mentionned is i thought there might be something wrong with my mixer inputs, i switched to inputs 3-4 /5-6 / 7-8 and the same results (evenm tried line in's). I'm using high quality neutrik cables (around 25$ per cable) and none are damaged. Note that i may never have discovered this as i usually hook evrything directly to my soundcard, it's only because i first decided to test with a direct XLR cable and when switched back to 1/4 TRS i noticed this loss of gain... Also tried with the Delta... my soundcard inputs have no pad/eq/gain trims as it has only balanced line ins located ina breakout box. Internally evrything is set-up to "+4 "

I really don't understand....All my other pres behaves the same way also as mentionned.

Thanks anyone who can answer this one!!!

Best regards

Phil
 
philboy said:
Note that i may never have discovered this as i usually hook evrything directly to my soundcard
Click to expand...

Was the soundcard input switched to -10?
 
" Was the soundcard input switched to -10?"

Hello,

No, i have carefull checked and the soundcard inputs are all set to +4...

I'm getting the same results either directly into the soundcard or directly into my mixer (tried various inputs), with all of my four different preamps, and i tried with many cables making sure the problem wasn't the cable itself...

Thanks

Phil...still trying to figure out and still troubleshooting...
 
How are you determining/calculating the loss?... that might help.
 
Hello,

I first noticed the loss simply by *hearing* the very noticeable difference. After hearing this i decided to watch on my mixer "VU Meter" to confirm what i was hearing. With any connector using a 1/4 TRS i'm getting -20 with the -15 led flashing to the mixer V.U. and only when i'm using direct XLR to XLR then i get -5 with +2 and +5 leds flashing.

Then i connected directly into the DELTA66 (setting to +4) and monitored via
Cubase SX 2.0's mixer large V.U. meter. Again 15dB of difference. Tested a third time with a mono guitar cable and scores the same level than with the 1/4 balanced...

Tried to swap inputs from 1 to 4, swapped wires, tried with different pres, always the same results.

I can only conclude : eventhough the connection is balanced, 1/4 TRS connections gives lower output than XLR's...

BTW anyone actually tried the test???

Regards

Phil
 
What's your mixer? It is very common for mic inputs to have more sensitivity than line inputs. Thus the same signal will have more level through the mic input than the line input.

My Mackie, for instance, gives +10 db at the mic input, even with the trim all the way down. The line input is -10db with the trim all the way down. The same signal sent into both of those inputs will show a 20db difference with the trim all the way down.
 
philboy said:
I can only conclude : eventhough the connection is balanced, 1/4 TRS connections gives lower output than XLR's...
Click to expand...

That's just not correct. There's some sort of technical problem or routing issue that you haven't sorted out yet.

What are you using as your sound source? Have you tried a test tone that is calibrated for +4? I don't doubt that you are getting the results you are, but it is without question some sort of equipment failure/mismatch.

The fact that the difference is around 15db leads me to think you still have some sort of level mismatch somewhere between -10 and +4. Also, you need to test those cables to make sure they are indeed wired properly.

A bal/unbal mismatch will give you about a 6db difference, which is why I think you might have a -10/+4 mismatch going somewhere. Keep looking.
 
Hello,

Thanks for helping evryone, really appreciated...

i'm using a Mackie 1202 VLZ and also tried a Behringer MX2004A i borrowd from a friend. Both gives exactly the same results. I have at least 30 pairs of cables : many XLR to XLR, many 1/4 to 1/4 TRS (All of them are nutrik high-quality studio microphone cables) 6 XRL to 1/4 TRS studio vables, many 1/4 mono...etc.... tried them ALL !!!!

Note that when i'm connecting to the DELTA66, i do bypass the mixer and connect directly from preamp out to delta in.... i don't see where i can have an impedence mismatch there?!?! The difference is huge. I just tried to pan hard left and right and monitor into my Autio-Technica phones, and it's clearly audible as one side is much louder.

Again, swapped inputs into the delta, tried inputs 1 to 4, tried directly to the mixer, same thing... no input pads, all mixers pres to 0, no EQ...

My sound source is a SM57 that i placed near the back of my computer monitoring the motherboard fan, which is a regular kind of white noise sound and permits to have a constant V.U. level.

I asked some friends if mine to do the test, can't wait to have their results...

I really wish i could explain this.... really confused....

Phil
 
On the 1202 there is 15db of difference between the line and mic inputs.
On the Behringer, it is 20 db.

I would imagine the Delta has a similar pad on the line inputs.

No mystery there.
 
philboy said:
I always thought there was no difference between XLR connectors and 1/4 TRS (NOT stereo... but BALANCED) connectors...

Doing some tests with my new Presonus Eureka preamp i noticed i'm loosing at least 15dB when using the 1/4 balanced TRS output to the 1/4 Balanced inputs of my mixer (instead of using XLR to XLR). Then i figured i could try with a special nutrik cable: XLR (from pre) to 1/4 TRS studio cable (to mixer) : still -15 dB. A bit confused, i tried with an ordinary 1/4 guitar mono cable from pre to mixer : still -15, no difference with the balanced 1/4 TRS... Seems that no matter where i put a 1/4 connector (weather balanced or unbalanced) in the chain i loose 15dB. The difference if huge very audible.

I thought it might be the mixer inputs so i tried in all the other inputs (total of 8) with the same results. Then i gave a try and hooked directly in my DELTA66 soundcard, and again the same thing. Then i thought it might be the preamp itself, so i hooked up with the same configurations in my three other preamps (A RP220, A Joemeek and a Focusrite), re-did all the tests and the results were exactly the same.

Please note that although i'm not an expert, i'm using proper cables and i'm not confusing "stereo 1/4" cables with balanced 1/4 TRS cables. Also i tried with various cables making sure there was no problem with the cable itself...

This makes me conclude that whenever you're using 1/4 connectors, weather it's unbalanced (TS) or balanced (TRS) you're loosing 15 dB compared to a direct XLR to XLR. Is this normal? Althought you might be able to run longer cables with Balanced 1/4 TRS instead of mono ones, i'm rather surprised of this gain loss. Any comments? (just trying to understand...)

Maybe someone better informed could explain?

Thanks for reading!

Kind regards

Phil
Click to expand...

I haven't read all the responses, but could it be that your XLR inputs are mic inputs (which are not padded) and your TRS inputs are line level inputs (which are padded)? Sounds like that's the difference you are hearing.
 
sdelsolray said:
I haven't read all the responses, but could it be that your XLR inputs are mic inputs (which are not padded) and your TRS inputs are line level inputs (which are padded)? Sounds like that's the difference you are hearing.
Click to expand...

That is exactly what is happening, pretty much.
 
arcaxis said:
I just looked at the block diagrams for two Behringer mixers I have. On the line inputs there appears to be a non-switchable resistive divider (padding) connected to the T&R connections. These do not appear on the XLR inputs. My guess is that the resistive divider does account for some apparent loss on the line inputs at least on Behringer mixers.
Click to expand...

It even says it in the manuals for the Mackie and Behri mixers. The mic input starts with 10db of gain. The line inputs start with -10db of gain.
 
" I haven't read all the responses, but could it be that your XLR inputs are mic inputs (which are not padded) and your TRS inputs are line level inputs (which are padded)? Sounds like that's the difference you are hearing."

Well... might be that... i actually didn't think about that... as i was thinking that the XLR input on a mixer (with the gain trim turned down) would give the same gain as a 1/4 TRS input on the same mixer...i might have been wrong about this... didn't know that a line level input is actually "padded"

This means that on a mixer channel, the line is less sensitive than a XLR input, eventhough the XLR in has the trim pot completely down?

If it's the case then it explains things...

Anyone else can comment on this?


Thanks evryone!


Phil
 
boingoman said:
On the 1202 there is 15db of difference between the line and mic inputs.
On the Behringer, it is 20 db.

I would imagine the Delta has a similar pad on the line inputs.
Click to expand...

Already done.
 
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