Hi, i have a preamp with a balanced output that i would like to use with an unbalanced power amp
I have read that a wrongly wired adapter could damage the preamp output section
The preamp was provided with XLR to RCA cables that are missing
Is there a way to connected it in a safe way ?
The preamp is an old pre processor from EAD the TheaterMaster 8800
Thanks a lot for any suggestion
Kind regards, gino
I have read that a wrongly wired adapter could damage the preamp output section
The preamp was provided with XLR to RCA cables that are missing
Is there a way to connected it in a safe way ?
The preamp is an old pre processor from EAD the TheaterMaster 8800
Thanks a lot for any suggestion
Kind regards, gino
It would depend on exactly how the preamp output is wired. A true balanced output should be quite happy with one side being grounded.
Hello and thank you very much indeed
Actually there is no indication in the manual ... the cables XLR to RCA mentioned are missing and no wiring schema is provided ... damn ...
I would not like to fry it ...
Is there a way to see if it is true balanced or not ?
I am willing to look inside in case.
I bought it because it has remote control and dac mostly.
Thanks a lot and kind regards, gino
Gino,
The XLR/RCA cables (that are missing) were most likely wired pin 1 to RCA outer and pin 2 to RCA tip. Pin 3 was probably left floating and not used. That is what you should recreate with a new pair of cables or adaptors.
Unfortunately, most XLR/RCA adaptors have pin 1 connected internally to pin 3. This is not a problem if used on XLR inputs on equipment, but on XLR outputs this "short circuit" grounds the pin 3 output and could, I suppose, cause damage to the active circuitry within your preamp. However, a lot of equipment utilizing XLR outputs may not have active signal on pin 3, but maybe just a resistor to ground.
You should investigate your preamp and see if pin 3 on the outputs is really alive with signal. If it is I would modify XLR/RCA adaptors (if used) and break the internal pin 1-3 connection. If not, you shouldn't have any issues using an adaptor.
Hope that makes sense.
Dave.
The XLR/RCA cables (that are missing) were most likely wired pin 1 to RCA outer and pin 2 to RCA tip. Pin 3 was probably left floating and not used. That is what you should recreate with a new pair of cables or adaptors.
Unfortunately, most XLR/RCA adaptors have pin 1 connected internally to pin 3. This is not a problem if used on XLR inputs on equipment, but on XLR outputs this "short circuit" grounds the pin 3 output and could, I suppose, cause damage to the active circuitry within your preamp. However, a lot of equipment utilizing XLR outputs may not have active signal on pin 3, but maybe just a resistor to ground.
You should investigate your preamp and see if pin 3 on the outputs is really alive with signal. If it is I would modify XLR/RCA adaptors (if used) and break the internal pin 1-3 connection. If not, you shouldn't have any issues using an adaptor.
Hope that makes sense.
Dave.
When I built passive XLR to RCA adapters for work I used a 1K resistor from 3 to ground and direct connect of pin 1 to shield and pin 2 to center on the RCA. If you have active outputs 1 phase sees the 1K. If it comes from a transformer without a grounded center tap the 1K completes the circuit. Active balanced behave properly also. Basically it covers all the bases with no nasty surprises.
G²
G²
Hi Dave, thank you very much for your helpful reply
This is what i have in mind actually. To left pin 3 floating.
I understand there is no problem in this case for the preamp outs.
Good ! i will do it. Thanks again.
it is always the same old story ... with 2 connections i am fine, more or less
With 3 i tend to mess everything .... 😱
and this is what i would like to avoid. I will leave pin 3 floating for sure
😱 how is that ??? they are cheating ??? 😡😀
Seriously ... what is the point of putting balanced 3 pins connections than ?
I am sincerely confused.
Thanks a lot again Dave. I really think that some tests are needed.
I do not want to ruin a piece that i like ... mostly aestitically i have to say
I will buy both some connectors and made some connections and test them
Then on the basis of the tests i will check some adapters
I have found some from Neutrik which i like immensely ... it is a pity that they stay hidden on the back of a unit
1pair Neutrik XLR Female to Teflon RCA Female Adaptor 99 99 Pure Silver Connect | eBay
But first some tests are really needed
Thanks a lot again. Kindest regards, gino
Hi and thanks a lot for the very helpful reply.
I have noticed that many units that come with XLR are not really balanced inside
If i understand well a truly balanced unit should have 4 identical amp stages
Most of them have only two
I wonder why ... only the cable run balanced ?
But i will leave the phase - pin floating just to be sure of no damage
I think i will have to do my own adapters
But better be safe than sorry
I do not want to destroy the unit.
Thanks again. Kind regards, gino
Gino,
I balanced interface doesn't need to have active signal on both sides. The balanced line is achieved with identical source resistances and not necessarily balanced signal conditions. A resistor to ground from pin 3 (if it's the same value as the output resistance of active circuitry on pin 2) still yields a balanced line with all the inherent advantages of that configuration.
Cheers,
Dave.
I balanced interface doesn't need to have active signal on both sides. The balanced line is achieved with identical source resistances and not necessarily balanced signal conditions. A resistor to ground from pin 3 (if it's the same value as the output resistance of active circuitry on pin 2) still yields a balanced line with all the inherent advantages of that configuration.
Cheers,
Dave.
Hi Dave thank you sincerely for your kind and valuable advice
I think i have found a DIY solution
I will buy a pair of 2ft. XLRs and i will cut them in the middle
Then with four RCAs like this ...
An externally hosted image should be here but it was not working when we last tested it.
i will make 4 adapters, for ins and outs ... connecting only the ground and the positive pins and leaving the negative floating
In this way i will not have any problem.
I would have preferred an off the shelf adapter ... but with this pins issue ..
Thanks a lot again. Kind regards, gino
Hi ... it's me again. Sorry 😱
I have the opposite issue now ... an headphone amp with XLR ins that i would like to connect with a dac with rca outs.
I have also a pair of RCA to XLR adapters that seem to shorten to ground the - phase.
Will using these adapters be safe for the headamp ? 🙄
I think so.
Once i shorten to ground a preamp input without any particular problem.
Any advice would be most welcome and appreciated.
Thanks a lot, gino 😀
I have the opposite issue now ... an headphone amp with XLR ins that i would like to connect with a dac with rca outs.
I have also a pair of RCA to XLR adapters that seem to shorten to ground the - phase.
Will using these adapters be safe for the headamp ? 🙄
I think so.
Once i shorten to ground a preamp input without any particular problem.
Any advice would be most welcome and appreciated.
Thanks a lot, gino 😀
It should be no problem on inputs at all. Those adaptors also have an internal short, but grounding an input should be fine in all cases.
Dave.
Dave.
Hi Dave ! thank you very much indeed ! i was not sure about this.
At present i listen HPs a lot and i have this HP amp with XLRs. Now that i have got this valuable advice i will by something nice to keep with the amp. My best dac is unbalanced.
Thanks a lot again. Kind regards, gino
- Status
- Not open for further replies.