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Balanced DI out (XLR) into poweramp input (1/4")

#22
MYLOWFREQ said:
A DI output is a Mic level signal which won't have enough juice for the power amp. Correct me if I got it wrong..
Click to expand...
Typically correct, but some amps have DI outs that can be switched between mic and line level.
 
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#25
el murdoque said:
I know that a cable is just a cable an that before the poweramp comes into play, cables should be shielded.
I just meant that I don't want to run a ten foot cable on a distance of about one foot on top of my cabinet.
Click to expand...

It shouldn't be difficult to find a 12" XLR to TRS cable. Live Wire (Guitar Center's "store brand") makes them.
 
#27
Its my understanding that you want to have TRS on the 1/4 plug. unbalanced has about 6db drop in signal when compared to balanced signal. The balanced signal should be low impedance, while the unbalanced is typically high impedance.

I have a xlr to unbalanced 1/4 so I can use my shure 58 on my rumble 15. Haven't tried line out from my rumble40 to the input on the rumble 15.
 
#28
with a 1/4 jack you can USUALLY tell how many conductors it expects by how it feels when you insert the cable.
If it "grabs" once before the cable is all the way in then it is a TRS jack. You can feel that sleeve contact settle into the tip groove before it's all the way in, I repeat... USUALLY
 
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#29
Drgonzonm said:
Its my understanding that you want to have TRS on the 1/4 plug. unbalanced has about 6db drop in signal when compared to balanced signal.
Click to expand...
Not always.
Here is some information that explains bal and unbal audio.
[Invalid or Expired Link Removed]

Here is some other info that also shows wiring diagrams for bal/unbal cables.
[Invalid or Expired Link Removed]
 
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#30
DanAdams said:
with a 1/4 jack you can USUALLY tell how many conductors it expects by how it feels when you insert the cable.
If it "grabs" once before the cable is all the way in then it is a TRS jack. You can feel that sleeve contact settle into the tip groove before it's all the way in, I repeat... USUALLY
Click to expand...

You might look into the jack with a flashlight and magnifying glass for the conductors, too. My guess is that since the Baby Sumo is a mono amp, I'd expect to find that it has a TS jack instead of a TRS.
 
#31
Old Garage-Bander said:
Betcha it costs almost as much as a 10 footer too.
Anyone who wants to roll their own, or make a 10 footer into a 9 and 1 footer... XLR connectors are about as easy to put on as anything.
Click to expand...

Last time I bought a few was for a patch bay, and they were pretty cheap from what I recall.
 
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#32
Drgonzonm said:
Its my understanding that you want to have TRS on the 1/4 plug. unbalanced has about 6db drop in signal when compared to balanced signal. The balanced signal should be low impedance, while the unbalanced is typically high impedance.
Click to expand...

Makes zero difference if the receiver end is not differential input.

Unbalanced outputs from preamps are almost always low impedance. Balanced/unbalanced has nothing to do with impedance.

I have a xlr to unbalanced 1/4 so I can use my shure 58 on my rumble 15. Haven't tried line out from my rumble40 to the input on the rumble 15.[/QUOTE]

The level is probably pretty low, this is a case where an impedance converting transformer can be helpful, because the step-up in voltage that occurs naturally as part of the impedance transform will better match the level that the amp's wants to see. The mic's output level is about -50dBu and the amp's input sensitivity is about -25dBu and the impedance transform is roughly +20dB going from low to high impedance. So (-50dBu + 20dB) = -30dBu which is pretty close.

DanAdams said:
with a 1/4 jack you can USUALLY tell how many conductors it expects by how it feels when you insert the cable.
If it "grabs" once before the cable is all the way in then it is a TRS jack. You can feel that sleeve contact settle into the tip groove before it's all the way in, I repeat... USUALLY
Click to expand...

You can usually tell what kind of jack is being used (TRS or TS), but this generally tells you little to nothing about if the ring is being used. I use TRS jacks with switching on all 3 poles for everything even though they are a little more expensive because they are mechanically more robust, with better PCB and contact stability. Many are wired in unbalanced configuration and the ring floats.

macmanlou said:
You might look into the jack with a flashlight and magnifying glass for the conductors, too. My guess is that since the Baby Sumo is a mono amp, I'd expect to find that it has a TS jack instead of a TRS.
Click to expand...

Just a guess, which is all you can do since there is almost no technical information on their website to base an accurate statement on. If I was looking for an amp, I would want to know if the input is balanced or unbalanced, and what the sensitivity is for rated output (and if the rated output is in RMS or peak units).
 
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#37
el murdoque said:
I have a question regarding this. I want to use an output, which is a balanced signal XLR plug, to drive a poweramp which has a 1/4" input. The only cables I found which are XLR female to 1/4" are microphone cables that are 10' and longer.

The output in question is that of an Ampeg PF20T and the input in question is that of a GSS Baby Sumo. I cannot tell if it is a balanced TRS input, but I think it is mono 1/4".
Click to expand...

I can see that you were dealing with very similar issue in March to one which I am dealing now in my recent thread:

Ampeg PF-20T to (power) amp

What 's been your experience since March? Do you like how the PF-20T sounds through Baby Sumo? THX
 
#39
Zbysek said:
I can see that you were dealing with very similar issue in March to one which I am dealing now in my recent thread:

Ampeg PF-20T to (power) amp

What 's been your experience since March? Do you like how the PF-20T sounds through Baby Sumo? THX
Click to expand...

I tried several things. The balanced out of the portaflex is not that strong. The best results were yielded by an audix T-50 k cable that is meant to be used with microphones. I switched to the pf 50 t since then and found that it has enough power for most of my needs.
 
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