jack to XLR - pre amp to power amp connection

[subdude]

i have a pre amp with 1/4" jack line out and an output impedande of 680 ohm that i want to connect to a power amp with XLR input and an input impedance of 20Kohms.
do i need a DI box or can a simple adapter be used?

thanks

[flyfisher]

You just need the appropriate cable.

It would be worth confirming the wiring of the 1/4" jack socket though. It might be wired "TRS", which is a 3-way connection (tip, ring, sleeve) using a 'stereo' jack socket and would allow a balanced connection between the pre-amp and power amp. Balanced wiring is less susceptible to interference, though the advantage is generally less important with short cables.

The pre-amp manual should describe the cabling requirements.

[markstuk]

You also want to check your preamp output is "hot" enough to drive the power amp properly... This is not always the case....

Cheers


Mark

[quote name='flyfisher' post='1370106' date='Sep 12 2011, 09:15 AM']You just need the appropriate cable.

It would be worth confirming the wiring of the 1/4" jack socket though. It might be wired "TRS", which is a 3-way connection (tip, ring, sleeve) using a 'stereo' jack socket and would allow a balanced connection between the pre-amp and power amp. Balanced wiring is less susceptible to interference, though the advantage is generally less important with short cables.

The pre-amp manual should describe the cabling requirements.[/quote]

[subdude]

regarding signal strength, plenty of signal arriving at the power amp, no problem there.

so i just get 2 cables with a 1/4 jack to a male XLR?

thanks for your input

[Alec]

[quote name='subdude' post='1370157' date='Sep 12 2011, 10:13 AM']so i just get 2 cables with a 1/4 jack to a male XLR?[/quote]

Probably, but without knowing what kit you've got at both ends, it's impossible to say for sure! Like Flyfisher says, for a proper job, you should find out if the output is balanced or not.

And does the power amp have jack inputs? If so, and if the pre's outputs are unbalanced, there's no great benefit in running over the XLRs, other than their latching capacity.

[subdude]

the pre amp has 2 unbalanced 1/4" jack output connectors.
the power amp has only 2 XLR inputs. if there were unbalanced inputs into the amp i would use them.

[bremen]

[quote name='subdude' post='1370283' date='Sep 12 2011, 12:12 PM']the pre amp has 2 unbalanced 1/4" jack output connectors.
the power amp has only 2 XLR inputs. if there were unbalanced inputs into the amp i would use them.[/quote]

Pin 1 jack sleeve, pin 2 jack tip. Pin 3 no connection.

[url="http://en.wikipedia.org/wiki/XLR_connector"]http://en.wikipedia.org/wiki/XLR_connector[/url]

[fillerbunny]

[quote name='bremen' post='1370288' date='Sep 12 2011, 02:18 PM']Pin 1 jack sleeve, pin 2 jack tip. Pin 3 no connection.

[url="http://en.wikipedia.org/wiki/XLR_connector"]http://en.wikipedia.org/wiki/XLR_connector[/url][/quote]

This, but with pin 3 also to earth / pin 1 for unbalanced XLR. Power amp manuals usually have this explained.

With my old Ampeg SVPCL (unbalanced 1/4" only) to Crown XLS (XLR only) this was the only way to connect without almost complete gain loss, and that's the way I connect my BBE 383 to QSC PLX. A regular 1/4" patch cable would do, but I prefer XLR whenever I can use them.

[subdude]

QUOTE (bremen @ Sep 12 2011, 02:18 PM)

Pin 1 jack sleeve, pin 2 jack tip. Pin 3 no connection.

[url="http://en.wikipedia.org/wiki/XLR_connector"]http://en.wikipedia.org/wiki/XLR_connector[/url]




bremen,

thanks for that, very helpful.


[quote name='fillerbunny' date='Sep 13 2011, 08:07 AM' post='1371351']
This, but with pin 3 also to earth / pin 1 for unbalanced XLR. Power amp manuals usually have this explained.

fillerbunny,

does this only apply if the XLR input is unbalanced or does one bridge pin 3 and pin 1 in any case when coming from an unbalanced 1/4 jack output?

thanks for the help.

[Bill Fitzmaurice]

[quote name='subdude' post='1370067' date='Sep 12 2011, 02:39 AM']i have a pre amp with 1/4" jack line out and an output impedande of 680 ohm that i want to connect to a power amp with XLR input and an input impedance of 20Kohms.
do i need a DI box or can a simple adapter be used?

thanks[/quote][url="http://www.rane.com/note110.html"]http://www.rane.com/note110.html[/url]

[fillerbunny]

[quote name='subdude' post='1371867' date='Sep 13 2011, 04:37 PM']fillerbunny,

does this only apply if the XLR input is unbalanced or does one bridge pin 3 and pin 1 in any case when coming from an unbalanced 1/4 jack output?

thanks for the help.[/quote]

If the XLR input was unbalanced, I guess only two pins would be connected anyway so no jumper bridging pins 1 & 3 would be necessary.

These manuals by [url="http://media.qscaudio.com/pdfs/plxuser.pdf"]QSC[/url] and [url="http://crownaudio.com/pdf/amps/139441.pdf"]Crown[/url] (pages 15 and 9, respectively) illustrate the correct wiring. Unbalanced XLR to TS plug cables are widely available, I used to use one I built myself but now use a commercial cable just for the security of not having to live in anticipation of my cold solders failing...

I have no clue what would happen if pin 3 wasn't earthed, I just know that a balanced TRS to XLR cable didn't work for me between a preamp with unbalanced output and a power amp.

[subdude]

thank you all for your input and informative links, all questions answered!