Balanced to single-ended converter (XLR to RCA / BAL to SE)

Discussion in 'DIY' started by purr1n, Jun 27, 2020.

  1. rhythmdevils

    rhythmdevils MOT: rhythmdevils audio

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    so weird! I eliminated everything else so it has to be that that was buzzing. Maybe it just needed a shake in the mail? :confused:
     
  2. loadexfa

    loadexfa MOT: rhythmdevils audio

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    Happy to loan you mine if you'd like to see if they all buzz for you. Perhaps something "special" about your house's electrical?
     
  3. rhythmdevils

    rhythmdevils MOT: rhythmdevils audio

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    Well it was fine for a couple months. Then I had to unplug everything to rearrange things and when I plugged it back in it was buzzing. And I didn’t drop it or anything. I actually put it on a pillow. So I know it’s not my place. It’s the audio fairy.
     
  4. loadexfa

    loadexfa MOT: rhythmdevils audio

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    Ahh right, I forgot it used to work. Trying mine could add a useful data point, up to you.
     
  5. rhythmdevils

    rhythmdevils MOT: rhythmdevils audio

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    I just had an email conversation with cable solutions which either makes me out to be an ignoramus because I admittedly have not read this whole thread or will be insightful and lead to more discussion. I bought one of these units used which had XLR input and RCA output. I used a regularly configured RCA cable for the output.

    ——————————

    XLR > RCA converter

    I’m curious if you sell the Jensen iso max PO-2XR and if I could buy one with XLR input and RCA outputs?

    Thank you
    Whitney

    —————-

    Hi Whitney,

    PO-2XR is a variation of PO-2XX, so you can order at the very bottom of the PO-2XX product page:
    www.cs1.net/products/jensen_transformers/PO-2XX.htm

    It is a special-order configuration, but we just happen to have one (1) unit in stock right now, so we could ship right away.

    Thanks,
    -Mark

    ———————

    Hi,
    Can you make it with XLR inputs and RCA outputs?

    This is the more robust version of the PI-2XX right? It’s 1:1, and will do a better job of converting balanced to single ended and allow me longer cable runs after the unit? (The PI-2XX says 1 meter max after the unit) )

    Thank you!!

    ————-

    I don’t think we’ve ever sold PI-2XR because the PC-2XR model is devoted specifically to converting XLR to RCA:

    www.cs1.net/products/jensen_transformers/PC-2XR.htm

    I just noticed the second part of your question…

    XLR levels are much higher than RCA levels, so it is typically desirable to reduce the levels in order to avoid over-driving the RCA inputs. The PC-2XR does just that. Unless one wanted to over-drive their RCA inputs for some reason, in which case either PI or PO might make sense.

    With either PI or PC, the output cables should be under a meter in length, but that’s not much of a problem, because one would typically want the longer runs to be done with balanced cables anyway.

    The only reason to prefer any PO model is because it can drive longer output cables, but that capability comes at the expense of slightly inferior specs. PO is typically used for live sound applications where it may not be practical to have the interface device on stage (and where room acoustics are more problematic than any loss of quality imposed by the PO).

    -Mark

    ————————-

    Oh ok so the PC-2XR is not 1:1. I’ve been told to get the 1:1 version. In which case he best sounding unit would be the PI-2XX and select RCA output connectors?

    Thank you! I will share all this information on the headphone forum Super Best Audio Friends where many people buy these units from you.

    Whitney

    ——————————

    Oh ok so the PC-2XR is not 1:1

    [MWS] True.

    I’ve been told to get the 1:1 version.

    [MWS] Why?

    In which case he best sounding unit would be the PI-2XX and select RCA output connectors?

    [MWS] If you overdrive your RCA inputs, it is hard to imagine that producing the best sounding anything. But I am admittedly working in the dark here, so if you would like to tell me more about your application, I may be able to offer you better advice.

    Thank you! I will share all this information on the headphone forum Super Best Audio Friends where many people buy these units from you.
    [MWS] Thank you.

    Whitney

    [MWS] -Mark

    ———————————

    Thanks for your advice! I have a Schiit Gungnir DAC and the XLR outputs sound better than the SE outputs. So it is very common for people to use this converter if they have an SE headphone amplifier so they can use the better sounding XLR output. It’s not much louder and doesn’t overdrive the RCA inputs on amps.

    But someone recently posted that the PO version has better transformers so would sound better hypothetically. And drive longer cable runs.

    I run a .5m rca cable out of the iso max into a switcher and one of its outputs needs a 1.5 meter RCA cable which is longer than the recommended 1 meter. So I was looking into the PO version because of this.

    But it seems you are saying it actually sounds worse.

    Since I don’t need volume attenuation, the best unit for sound quality would then be this one?

    www.cs1.net/products/jensen_transformers/PI-2XX.htm

    Thanks again!

    —————————

    PI-2XX with TRS phone connectors becomes PI-2PP, which is also a very unusual configuration (we have never sold one that way), meaning that it will be special order, with significant lead time and not eligible for return. I would have to ask the factory for the expected lead time, but they have been running weeks (and even months) behind as a result of the pandemic. The website states 3 days, but that was written in better days…I would not expect that to be true right now.

    If that’s what you want, then so be it, but please be aware that you’ll still need conversion cables to interface with those RCA outputs – you cannot just plug in a TS plug and expect that to work. And the conversion cables need to be wired in a specific way – in other words, not just a 2-conductor cable connected to a 3-conductor plug. And if you’re going to be using conversion cables anyway, then it probably makes more sense to go with the PI-2XX, since that configuration is not special order and they are currently in stock.

    -Mark
     
  6. crenca

    crenca Friend

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    ^ What is it about these three products that causes so much confusion? I know I am confused after all that.

    You want either a PI or PO (both 1:1), as the PC (4:1) sounds bad to every SBAF member who has tried it. I rated the PI vs PO close enough, but at least one other SBAFer felt the PO edged out the PI, YMMV - but since you need a 1.5 meter RCA run why not get the PO just to be sure? I think Mark of CableSolutions has it backwards, the PO has slightly better bass distortion/linearity measurements according to Jensen's spec sheets (either that, or I have it backwards).

    So you want a PO (or PI), in a "PO-2XR" configuration - the X for XLR input, and R for RCA output.

    By the way when I ordered mine a month or two ago, Mark told me it would be a special order then sent me an email the next day saying they had at least one in stock so he got it to me within the week,.
     
  7. rhythmdevils

    rhythmdevils MOT: rhythmdevils audio

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    What about needing a “conversion” cable to use the RCA outputs?

    this is definitely confusing and I have a hard time believing he doesn’t know what he’s taking about. I also trust the knowledge and impressions here so.....wtf
     
  8. crenca

    crenca Friend

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    I don't know, but I am guessing he believes you need a 4:1 conversion, whether you understand this or not, and so wants to sell you a "conversion cable" that does this?? Just a guess. I never got in a back and forth with him as to what I need, I just told him what I want so maybe he never got to the point of trying to "help" me ;)
     
  9. rhythmdevils

    rhythmdevils MOT: rhythmdevils audio

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    it sounds like he’s referring to converting from a balanced signal to SE not 4:1. He talks about 3 pin to 2 pin.

    but I guess everyone here has been plugging in regular RCA cables into their PI-2XR units with no problems?
     
  10. hifiandrun

    hifiandrun Almost "Made"

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    Hi @rhythmdevils, I don't have direct experiences but I had phone conversations with David at the Cinemag previously when I was doing a DIY converter using Cinemag audio transformers.

    The Cinemag has a well know model of line transformer CMLI-15/15B2, which has been mentioned many times on the SBAF. The difference between "15/15B" model versus "15/15B2" model has been the later is a double shielding variant. The CMLI-15/15B2's specifications are very similar to the Jensen's line level signal transformers used in PI-2xx. The PI-2XR would be for XLR inputs (two channels) to RCA outputs (also two channels). The PI-2RX would be for RCA inputs to XLR inputs conversion. The PI-2XX is for XLR inputs and XLR outputs, which is mainly for noise reduction (avoid ground-loop, etc). After my conversation with David at Cinemag, my layman understanding with some triangulation are listed below:

    1. The two transformers in PI-2xx carry the lowest signal distortion specifications amongst PI-2xx, PC-2xx, and PO-2xx. The biggest differences is the designated impedances. The transformers in the PI-2xx have a higher impedance (11k ohm for Jensen transformers or 15k ohm for Cinemag CMLI-15/15B2), with the turn ratio of 1:1. The transformers in PC-2xx is a 4:1 ratio (impedance is 10k ohms to 600 ohms), and this is the "weird" sounding one mentioned by @crenca. Note that the 4:1 turn ratio results in 16:1 impedance ratio. The two transformers in PO-2xx have lower impedance at 600 ohms on both side thus the turn ration is 1:1 as well.

    2. The impedances are related to the distortions and the applications. In general, higher the impedances, thinner the internal wiring is required. The transformer is easier to be designed to obtain lower distortion. However, the problem (e.g. limitation) is mainly on the output signal side. If the wire connected from the output of the PI-2xx to the input of the downstream device (commonly it will be a pre-amp) is too long, the signals will be prone to noises. David emphasize that the output line-level cables should be as short as possible, no more than 6 feet. This is usually not a problem if a PI-2XR is used between a Yggdrasil or a Gungnir Multibit and a pre-amp. The XLR cables from Yggdrasil to the PI-2XR can be long. But the RCA cables from PI-2XR to the pre-amp should be as short as possible to reduce noise and distortion.

    3. In some other user cases, for example, someone wanted to convert a single-ended signal to XLR, as in my case, using a Saga as a pre-amp and two Vidars or Aegirs as mono-blocks. Usually, the XLR cable from the Saga to the two Aegirs need to be long. One reason is that people prefer to put the mono-blocks close to the speakers so that the speaker cables can be shorter. Anyway, in this case, the PO-2RX would be a better choice because the specification impedances are only 600 ohms.

    4. Considering the transformer impedances, it doesn't really matter much whether the cables are single-ended (RCA) or balanced (XLR). The most important concern is the impedance on the output side of the transformer. The transformers with higher impedances require shorter cables to reduce the chance of noise or distortion of signals. David didn't explain to me in details as this is very compilated. In many cases, he said it would be a "trial and error" excise.

    Thus, my understanding about all the 3 Jensen converter boxes is: 1) the PI-2XR for XLR -> RCA application would yield the best sonic results. It is important to keep the output RCA cables as short as possible. 2) the PO-2xx box is for the situation where long output cables can not be avoid. However the sonic result might be slightly compromised or at least "colored". In my case, I made a converter box between my Saga and my two Aegirs using two CMLI15/15B based on David suggestions. I made sure that the output XLR cables were short (2.5 feet long).

    The line signal transformer is an interesting beast. It may slightly change the sound. The biggest improvement however, is due to the signal ground isolation. In my DIY project, I felt that the sound seemed quieter and cleaner to me. although there is no easy A-B test for this.

    Again, all the above was just my anecdotical and layman understanding. Please take them with 50 - 100 grams of salt.
     
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    Last edited: Mar 17, 2021
  11. Armaegis

    Armaegis Friend

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    Just buy the PO-2XX that's in stock and use an XLR(f)->RCA(m) adapter cable that grounds pin3* . Since the output of the PO-2XX is floating via the transformer, grounding pin3 in this case does no harm.

    * actually, this part isn't even important since most likely your amp RCA input shell is tied to ground anyways, so go ahead and leave pin 3 alone, who cares
     
  12. rhythmdevils

    rhythmdevils MOT: rhythmdevils audio

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    Haha the PO-2XR or the PI-2XR?

    I’m going DAC > iso max > .5m rca > switcher > 1.5m rca > amp (for one of my amps)

    If 2m rca out of the iso max is fine then I should be good with the PI-2XR which I have currently assuming it’s not broken somehow...
     
  13. Taverius

    Taverius Smells like sausages

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    I'm just happy that trusted ears couldn't find a noticeable difference between the pi and po.

    Mine is a PO, apparently - I had to check, because I honestly haven't cared enough to remember - with RCA outs.

    Filing this under "good enough, stop worrying about it".
     
  14. rhythmdevils

    rhythmdevils MOT: rhythmdevils audio

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    You need to worry more.
     
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  15. hifiandrun

    hifiandrun Almost "Made"

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    One meter (1m) was strongly suggested by David for his CMLI-15/15B. And he said that 2 meters was the maximum tolerable length without significant draw back. Since the ISO-max in your planned set up will be in front of the switcher, which could potentially add other issues (wires exposed in the switcher without shielding for example), PO-2XR should be the safer bet. My analogy was like this: considering the aspects of impedance matching of the upstream / downstream gears, I'd think that the PI-2xx is a part of the input circuit of the pre-amp, where as the PO-2xx is belong to the circuit of the DAC. One exception, in case the switcher is a balanced design, e.g. XLRs in and XLRs out, it would be connected to the inputs of the ISO-MAX (before the ISO-MAX), then the PI-2XR can still be considered - because it sits directly before the pre-amp or amp, where very short cables can be used.
     
  16. rhythmdevils

    rhythmdevils MOT: rhythmdevils audio

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    This thread is crazy. We’ve got a rep at cable solutions saying the PO sounds worse, 2 SBAFers saying they sound a little better. And different opinions on cable lengths after the iso max unit.

    anyone else have an opinion? It would be good for all of us to figure this out. (Or at least me :p)

    :bow:
     
  17. crenca

    crenca Friend

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    @rhythmdevils , I would go with what the Jensen is saying in a rather straightforward manner by comparing these two sources:

    https://www.jensen-transformers.com/product/po-2xx/#section-2

    https://www.jensen-transformers.com/product/pi-2xx/#section-3

    Looking at the specs and the graphs, it is clear that the PO model is made for longer cable runs and has a bit better THD distortion specs and linear FR in the bass. I suppose the question would be how the various input/out impedance ratings play with your equipment in your particular system. In mine between a Gun MB A2 and an OG Saga with very short (< 2 feet) SE & Bal cables they both sound substantially the same....but I do have lots of wax in my ears :p
     
  18. Armaegis

    Armaegis Friend

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    Just ditch all of the crazy hoodoo and spending money on middlemen converting whatchamacallits and get yourself a balanced amp/preamp. There, I fixed your problem :D

    Just go ahead and trust the ears of the sbaf grunts. The cable guy is rolling his eyes at you right now and just wants to sell you something and figures you're another nutjob with audio nervosa. He already said they have a PO in stock right now; just get that and save yourself the wait, get the appropriate converter cable that you need anyways, and hop off the crazy train.
     
  19. Erroneous

    Erroneous Friend

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    I mean, that's all of us here and why this is currently a 7 page thread. Otherwise the RCA outs would be in use. :)
     
  20. rhythmdevils

    rhythmdevils MOT: rhythmdevils audio

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    I’m borrowing @loadexfa ‘s PI-2XR and I just got it and it’s like 1/3 the weight of mine. So I looked into my image archives and it turns out I have the DM2-2XR ie the DM2-2XX with rca outputs.

    anyone have any idea what the DM2-2XX is? Cable solutions doesn’t sell it but Markertek does.

    https://www.markertek.com/product/j...-line-output-isolator-1-to-1-ratio-xlr-in-out

    Here’s a picture of the bottom of mine. Clearly whatever transformers are in this thing are way heavier than the PI-2XX

    [​IMG]
     

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