Looking for intel regarding connecting a Berhinger DCX2496 w my (150ohm output) single ended tube pre-amp.
Unfortunately I don't have a lot of specs on my discontinued preamp.
I am using the second out of the preamp to the Berhinger to be used as a low pass to amps>subs.
A couple of questions:
What equipment can measure the specs I need to understand my preamp. And what info am I looking for? Ohms? Voltage?
Lots of XLR/RCA connection "boxes" out there. Mostly designed for pro applications. I guess I could buy some and experiment... but thought I would cast about for successful home audio applications.
I am working through trouble shooting. I made my own cables (XLR on one side and RCA on other) and am going to move the hot pin around and see if that works. Even if it does work, I don think it solves the impedance mis-match. Whats the best practice here or... not a big deal, don't worry about it if it sounds good?
Thanks in advance for any help or insight here.
Unfortunately I don't have a lot of specs on my discontinued preamp.
I am using the second out of the preamp to the Berhinger to be used as a low pass to amps>subs.
A couple of questions:
What equipment can measure the specs I need to understand my preamp. And what info am I looking for? Ohms? Voltage?
Lots of XLR/RCA connection "boxes" out there. Mostly designed for pro applications. I guess I could buy some and experiment... but thought I would cast about for successful home audio applications.
I am working through trouble shooting. I made my own cables (XLR on one side and RCA on other) and am going to move the hot pin around and see if that works. Even if it does work, I don think it solves the impedance mis-match. Whats the best practice here or... not a big deal, don't worry about it if it sounds good?
Thanks in advance for any help or insight here.
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Have a look at this Hypex app note - towards the end there's a clear diagram for recommended way to connect RCA o/p gear into an XLR input.
The Rame app note gives even more info
The Rame app note gives even more info
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So what you want is a mini howto on connecting an unbalanced output to a balanced input, and do it properly? No problem then:
On the unbalanced side, use coax.
On the balanced side, use matching shielded twisted pair cabling.
You can pretty much transition anywhere in between, giving you liberties WRT cable construction.
Transitioning unbal > bal involves the following connections:
Signal --> Hot
Ground (--> [Zout]) --> Cold
Ground --> Shield (may need to be interrupted in some cases = "ground lift")
[Zout] signifies a replica of the signal-side output impedance, as closely as possible. If the 150 ohms are from a cathode follower, they'd hardly be ultra-precise, so in that case I'd look up the coupling capacitor, make a series R-C with the same value and a 150R, and call it a day. (In an "sand" output stage with very low internal output impedance plus an external series resistor, one would use that resistor value.) You could always measure output impedance if you wanted to get really fancy. Eh, whatever. CMRR should be plenty decent as-is at this point, it's not like we're talking kOhms worth of mismatch.
I don't know how it is with the 2496 gear, but other Behringer stuff at the time does not seem to follow AES48-2005 guidelines when it comes to XLR pin 1 (shield) routing (in a nutshell: go straight to chassis or go bust). A ground lift may prove handy under some circumstances, these being that you cannot get a totally clean signal. Anyway, the input can take very high levels... should be about +16 dBu unbal, that's roughly 5 Vrms, so don't be shy. Input impedance is roughly 35k bal, usually any output with at least a cathode follower should be fine with that.
I don't know whether you're aware of the mods for these devices. Seems like they used a number of surface mount ceramic caps in the nF down to hundreds of pF range in the audio path that for some unfathomable reason were chosen to be the smallest (and possibly cheapeast) possible size with a correspondingly crummy dielectric... that's not doing high-frequency distortion figures any favors. 2n2 are the worst offenders but there's some 390p and 220p, too. Not sure about the 100p right now. Stock performance is about 0.03% at 20k if memory serves, you can get this down by about an order of magnitude. It's not "bad bad" and still likely to be swamped by speakers and amps in many circumstances, but the standards of DA/AD devices are somewhat higher than that.
On the unbalanced side, use coax.
On the balanced side, use matching shielded twisted pair cabling.
You can pretty much transition anywhere in between, giving you liberties WRT cable construction.
Transitioning unbal > bal involves the following connections:
Signal --> Hot
Ground (--> [Zout]) --> Cold
Ground --> Shield (may need to be interrupted in some cases = "ground lift")
[Zout] signifies a replica of the signal-side output impedance, as closely as possible. If the 150 ohms are from a cathode follower, they'd hardly be ultra-precise, so in that case I'd look up the coupling capacitor, make a series R-C with the same value and a 150R, and call it a day. (In an "sand" output stage with very low internal output impedance plus an external series resistor, one would use that resistor value.) You could always measure output impedance if you wanted to get really fancy. Eh, whatever. CMRR should be plenty decent as-is at this point, it's not like we're talking kOhms worth of mismatch.
I don't know how it is with the 2496 gear, but other Behringer stuff at the time does not seem to follow AES48-2005 guidelines when it comes to XLR pin 1 (shield) routing (in a nutshell: go straight to chassis or go bust). A ground lift may prove handy under some circumstances, these being that you cannot get a totally clean signal. Anyway, the input can take very high levels... should be about +16 dBu unbal, that's roughly 5 Vrms, so don't be shy. Input impedance is roughly 35k bal, usually any output with at least a cathode follower should be fine with that.
I don't know whether you're aware of the mods for these devices. Seems like they used a number of surface mount ceramic caps in the nF down to hundreds of pF range in the audio path that for some unfathomable reason were chosen to be the smallest (and possibly cheapeast) possible size with a correspondingly crummy dielectric... that's not doing high-frequency distortion figures any favors. 2n2 are the worst offenders but there's some 390p and 220p, too. Not sure about the 100p right now. Stock performance is about 0.03% at 20k if memory serves, you can get this down by about an order of magnitude. It's not "bad bad" and still likely to be swamped by speakers and amps in many circumstances, but the standards of DA/AD devices are somewhat higher than that.
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Perhaps read the User Manual?
https://www.parts-express.com/pedocs/manuals/248-669-behringer-dcx2496-manual-41812.pdf
The connections for unbalanced send are documented. You do NOT need to fret about impedances and such in this situation.
https://www.parts-express.com/pedocs/manuals/248-669-behringer-dcx2496-manual-41812.pdf
The connections for unbalanced send are documented. You do NOT need to fret about impedances and such in this situation.
Attachments
OK. I saw that. But the Berhinger is not picking up the signal from my Pre-Amp.
The pre-amp has two active outputs. Both set of outputs work fine when sending signals to my main amps as I have swapped them repeatedly. As mentioned, I have been successful w sending signal to both the mains and the Berhinger. But have had intermittent problems w losing that signal. I couldn't figure out why the inconsistencies, but I mistakenly blamed it on the Berhinger due to the problems discussed by its many users... bad cabling, loose solders, bad input boards, etc..
I have an Audio Note DAC that has both balanced and unbalanced analog outputs. Both output types are passing a signal on the Berhinger. So, I know the Berhinger works (to the extent its receiving a signal), and I know my cables are functioning.
BTW... the cable is DIY w RCA on one end and XLR on the other. I have tried moving the hot pin around w no luck.
The manual says that pins 1 and 3 have to be bridges. Not sure if I need to bridge on both sides of the cable or just one side (I'm assuming the RCA side). Anyway... I've tried both ways w no luck.
The pre-amp has two active outputs. Both set of outputs work fine when sending signals to my main amps as I have swapped them repeatedly. As mentioned, I have been successful w sending signal to both the mains and the Berhinger. But have had intermittent problems w losing that signal. I couldn't figure out why the inconsistencies, but I mistakenly blamed it on the Berhinger due to the problems discussed by its many users... bad cabling, loose solders, bad input boards, etc..
I have an Audio Note DAC that has both balanced and unbalanced analog outputs. Both output types are passing a signal on the Berhinger. So, I know the Berhinger works (to the extent its receiving a signal), and I know my cables are functioning.
BTW... the cable is DIY w RCA on one end and XLR on the other. I have tried moving the hot pin around w no luck.
The manual says that pins 1 and 3 have to be bridges. Not sure if I need to bridge on both sides of the cable or just one side (I'm assuming the RCA side). Anyway... I've tried both ways w no luck.
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You need a cable with these connections:
output signal (RCA center) --> pin 2
output ground --> pin 3 + pin 1
That has got to work. Make sure you do not accidentally reverse unbalanced signal and ground, as this could short the signal out.
If you are "losing" the signal, does it affect both preamp outputs or just one? Have you checked your DIY adapter cable for an intermittent short?
Maybe you should attempt to write down what exactly happens in which scenario, with as many details as possible. Having the "raw data" so to speak makes it much easier for us to assess the situation.
Congrats on getting "Behringer" wrong consistently, BTW
output signal (RCA center) --> pin 2
output ground --> pin 3 + pin 1
That has got to work. Make sure you do not accidentally reverse unbalanced signal and ground, as this could short the signal out.
If you are "losing" the signal, does it affect both preamp outputs or just one? Have you checked your DIY adapter cable for an intermittent short?
Maybe you should attempt to write down what exactly happens in which scenario, with as many details as possible. Having the "raw data" so to speak makes it much easier for us to assess the situation.
Congrats on getting "Behringer" wrong consistently, BTW
OK... A recap. I have a Preamp w 2 active outputs. I send one out to my mains and send the other output to a DCX. The DCX is not picking up the signal. I have swapped those outputs and the mains work fine on both outputs and the DCX wont work on either outputs.
To make sure the DCX was working properly, I used my Audio Note DAC that has both balanced and unbalanced analog outputs. Both signals get picked up by the DCX. So, I know the DCX works and I know my DIY cables work.
Why wont the DCX pick up the signal from my preamp?
To make sure the DCX was working properly, I used my Audio Note DAC that has both balanced and unbalanced analog outputs. Both signals get picked up by the DCX. So, I know the DCX works and I know my DIY cables work.
Why wont the DCX pick up the signal from my preamp?
I am trying to send a signal from my pre-amp /RCA outputs (Emotive Audio- Epifania) to the DCX/ XLR inputs and then the DCX/XLR outputs to amps>subs /RCA inputs.
Some info about my preamp: it says its phase is inverted. Do you think that has any effect?
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Good question. I cant definitively answer that question. I think it was both most of the time but I remember a few times where one side was not puting out.
A couple more info nuggets I haven't shared.
The manufacturer made some modifications to the preamp so that it would play nice w my amps, which are Eico HF-60's. The Eico's have 1Mohm input ( that's what my tech told me anyway) and use the 16ohm tap on the OPT's.
FWIW- The preamp states that the signal phase is inverted.
Sounds like one inverting gain stage + a cathode follower or something, a very common setup for a basic tube pre. What sort of tube complement does it have, maybe two dual triodes (e.g. 12AU7) and perhaps a rectifier?
Troubleshooting an intermittent fault can be very tedious, making it hard to even isolate the source of the problem.
I use one of these, by the way: ART CLEANBoxPro Stereo Balanced/Unbalanced Converter
For $69 it is a good buy and you don't have to rely on a cable. But you may have more issues, I am not figuring it out from what you are saying.
For $69 it is a good buy and you don't have to rely on a cable. But you may have more issues, I am not figuring it out from what you are saying.
Here is one review on the PE site of the above link:
Does everything I ask of it.
First of all, I'd like to state how I use it and what I've been able to achieve:I have connected the home audio level outputs (-10 dB RCA) of my uDac to the unit, connect a pair of balanced xlr cables between the unit and a DCX2496.Previously I was unable to get a full +4 dBu signal to come out of my home audio device(s) for the purpose of maximum signal to noise and control within my pro audio DCX2496, i've also tried a portable music player, but since getting this device I have gotten nothing but strong clean input to my DCX. The output volume controls are also handy in case you want a more fine control on your DAC.
Does everything I ask of it.
First of all, I'd like to state how I use it and what I've been able to achieve:I have connected the home audio level outputs (-10 dB RCA) of my uDac to the unit, connect a pair of balanced xlr cables between the unit and a DCX2496.Previously I was unable to get a full +4 dBu signal to come out of my home audio device(s) for the purpose of maximum signal to noise and control within my pro audio DCX2496, i've also tried a portable music player, but since getting this device I have gotten nothing but strong clean input to my DCX. The output volume controls are also handy in case you want a more fine control on your DAC.
It works perfectly on both outputs. Sounds like a dream..., on the mains anyway.
The attenuator itself is made by Khozmo.
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