Hi Zen-Mod,
you know I've got some problems with one Shunty.
Can you send me an email with the order Informations, because I'll need a new one.
Your email Filter filters my mails out
Best regards
Felix
you know I've got some problems with one Shunty.
Can you send me an email with the order Informations, because I'll need a new one.
Your email Filter filters my mails out
Best regards
Felix
Another beginner's question, I'm afraid...
The cookbook is pretty clear about what to do for unbalanced use - use XLR jacks and "tie (solder) pins 1&3 together inside the cable jack". I have just bought the necessary materials to make the cables to connect the pumpkin (not yet finished) to the DAC on one side and my diy F4 on the other, so each cable will have an RCA plug on one end and an XLR on the other. In the shop I talked to two guys about what was the best cable to use, and ended up following their advice and bought two-core shielded microphone cable. Now these guys (who sell mostly to the pro audio market) advised me to connect the XLR end normally, and then connect the -ve and shield at the RCA end, rather than the XLR end, as ZenMod recommends. So my question: does it make any difference? Obviously there is an electrical connection between pins 1 and 3, as required, but I presume the connection has greater impedance (admittedly small, if the cable is good, but surely more than a direct solder connection...) It goes without saying that I can just do things as the cookbook says, but I'd like to understand if possible...
Cheers
Nigel
The cookbook is pretty clear about what to do for unbalanced use - use XLR jacks and "tie (solder) pins 1&3 together inside the cable jack". I have just bought the necessary materials to make the cables to connect the pumpkin (not yet finished) to the DAC on one side and my diy F4 on the other, so each cable will have an RCA plug on one end and an XLR on the other. In the shop I talked to two guys about what was the best cable to use, and ended up following their advice and bought two-core shielded microphone cable. Now these guys (who sell mostly to the pro audio market) advised me to connect the XLR end normally, and then connect the -ve and shield at the RCA end, rather than the XLR end, as ZenMod recommends. So my question: does it make any difference? Obviously there is an electrical connection between pins 1 and 3, as required, but I presume the connection has greater impedance (admittedly small, if the cable is good, but surely more than a direct solder connection...) It goes without saying that I can just do things as the cookbook says, but I'd like to understand if possible...
Cheers
Nigel
take the twisted pair inside the microphone cable all the way to the RCA and connect them. These will carry the flow and return.
Connect the screen at the send end and use it to attenuate interference on the signal. Leave it unterminated at the RCA end.
Now connect the free pin as instructed.
If your were to convert the input of your receiver end to XLR then you could use XLR all the way and connect the free pin inside the receiver, or better still install a transformer to convert from true balanced to unbalanced.
Connect the screen at the send end and use it to attenuate interference on the signal. Leave it unterminated at the RCA end.
Now connect the free pin as instructed.
If your were to convert the input of your receiver end to XLR then you could use XLR all the way and connect the free pin inside the receiver, or better still install a transformer to convert from true balanced to unbalanced.
Andrew, many thanks for your reply. A few further queries:
So I connect pin 2 of the XLR to the centre pin of the RCA and pin 3 to the outer part of the RCA, being + and - respectively, this is clear. The "send end" you mention is the XLR in the case of the output cable, and your post is clear that I connect the screen to pin 1 of the XLR (and then connect pins 1 and 3), but I also need input cables to connect up the source, for which the send end is the RCA. I presume I connect the screen to the XLR in this case also ??
You mean the receiver end in the power amp, right? That's a tempting idea, actually. The pin connection idea is easy - do you have a link or something that would explain the transformer idea?
One last question: Why is the method you describe better than that proposed at the shop? Is it a question of the impedance, as I wondered in my earlier post? Or is it better screening this way?
In any event, many thanks again
Cheers
Nigel
AndrewT said:
So I connect pin 2 of the XLR to the centre pin of the RCA and pin 3 to the outer part of the RCA, being + and - respectively, this is clear. The "send end" you mention is the XLR in the case of the output cable, and your post is clear that I connect the screen to pin 1 of the XLR (and then connect pins 1 and 3), but I also need input cables to connect up the source, for which the send end is the RCA. I presume I connect the screen to the XLR in this case also ??
You mean the receiver end in the power amp, right? That's a tempting idea, actually. The pin connection idea is easy - do you have a link or something that would explain the transformer idea?
One last question: Why is the method you describe better than that proposed at the shop? Is it a question of the impedance, as I wondered in my earlier post? Or is it better screening this way?
In any event, many thanks again
Cheers
Nigel
transformer input
look up jensen, cine mag, rane etc.
If you require to connect RCA source to XLR receiver, then consider adapting the RCA source to psuedo balanced output.
look up jensen, cine mag, rane etc.
If you require to connect RCA source to XLR receiver, then consider adapting the RCA source to psuedo balanced output.
Re: transformer input
1. "pseudo balanced output" means the transformer idea? I'm interested in trying this if practical, but if not (at least initially), and I have to use RCA to XLR from the DAC to the pumpkin, then do I use the same wiring scheme for input that you described for output? Or are you really saying this is a bad idea?
2. Otherwise, is my post above correct? That is, did I understand your previous post correctly? I'd still like to understand the benefits of this wiring compared to connecting things at the RCA end.
Thanks
Nigel
AndrewT said:
1. "pseudo balanced output" means the transformer idea? I'm interested in trying this if practical, but if not (at least initially), and I have to use RCA to XLR from the DAC to the pumpkin, then do I use the same wiring scheme for input that you described for output? Or are you really saying this is a bad idea?
2. Otherwise, is my post above correct? That is, did I understand your previous post correctly? I'd still like to understand the benefits of this wiring compared to connecting things at the RCA end.
Thanks
Nigel
look at Jensen and see that psuedo balanced amounts to one extra resistor and one extra capacitor.
It's a very cheap way to allow a balanced input to perform as a balanced input should.
It's a very cheap way to allow a balanced input to perform as a balanced input should.
Kamel said:
my neobee account can be nervous sometimes
my gmail account is - well , gmail account .
try once more to write on my >sasica5@gmail.com< account , and if that not succeed to reach me , write via forum mail thingie what you want
😉
@ njepitt
what Andrew wrote is pretty much correct ( look here , if you didn't already - http://www.jensen-transformers.com/an/an003.pdf , and look at that site for more interesting documents ) .
just few things :
- I'm strong proponent of xformers , feeling things in way that I put xformer in signal path whenever I can , sometimes even without thinking are they completely adequate for task/implementation position
; one example is - even if output impedance of cheap CD player isn't low enough , puttin' phone repeater xformer (ancient 600:600 nickel toroid thingie) can spice sound pretty well , and make it pretty listenable ...
-
is bal/unbal and unbal/bal converter itself , but also pretty good "paraphase" stage .....
you don't need to ensure bal signal to it , to ensure proper functionality , even if some parameters are certainly worse than using proper bal input scheme . SUSY functionality will suffer ( ie. will not be in full blast amount) but - in which way compromise will be smaller ( worse sounding) depends really of particular case ;
meaning - is it better to use xformer on source side ( good xformers aren't cheap , and there is always question is preceding stage able to feed them) , or is it better to use "not entirely SUSY" ( ie. unbal feed to ) ........ ?
choice is to you ...... if some element in chain is unbalanced , you need somewhere transition to balanced ; where is most appropriate - sometimes only matter of money involved .
my advice can be - finish first thing first - use RCA-XLR cables made in whichever way you want - for enjoying your newly made amplification chain , then experiment with most adequate ways of converting your source to balanced one .
what Andrew wrote is pretty much correct ( look here , if you didn't already - http://www.jensen-transformers.com/an/an003.pdf , and look at that site for more interesting documents ) .
just few things :
- I'm strong proponent of xformers , feeling things in way that I put xformer in signal path whenever I can , sometimes even without thinking are they completely adequate for task/implementation position
; one example is - even if output impedance of cheap CD player isn't low enough , puttin' phone repeater xformer (ancient 600:600 nickel toroid thingie) can spice sound pretty well , and make it pretty listenable ...-
is bal/unbal and unbal/bal converter itself , but also pretty good "paraphase" stage ..... you don't need to ensure bal signal to it , to ensure proper functionality , even if some parameters are certainly worse than using proper bal input scheme . SUSY functionality will suffer ( ie. will not be in full blast amount) but - in which way compromise will be smaller ( worse sounding) depends really of particular case ;
meaning - is it better to use xformer on source side ( good xformers aren't cheap , and there is always question is preceding stage able to feed them) , or is it better to use "not entirely SUSY" ( ie. unbal feed to
) ........ ?choice is to you ...... if some element in chain is unbalanced , you need somewhere transition to balanced ; where is most appropriate - sometimes only matter of money involved .
my advice can be - finish first thing first - use RCA-XLR cables made in whichever way you want - for enjoying your newly made amplification chain , then experiment with most adequate ways of converting your source to balanced one .
AndrewT and ZenMod,
I've already found an003.pdf and am making my way through it now. I think I'll follow ZM's advice and try the pumpkin just with RCA-XLR cables and see how we go. Once I understand more of the Jensen documents we'll see what's best.
Thanks again.
Cheers
Nigel
I've already found an003.pdf and am making my way through it now. I think I'll follow ZM's advice and try the pumpkin just with RCA-XLR cables and see how we go. Once I understand more of the Jensen documents we'll see what's best.
Thanks again.
Cheers
Nigel
)
I've spent some time looking at Jensen's document an003.pdf and a few things asre making more sense. This .pdf article gives four options for unbalanced output to balanced input. The first (2.1) is a simple cable, configured *exactly* as the guy in the shop said yesterday, which also appears to be how Douglas Self recommends on his site. (I presume the differencefrom what AndrewT was recommending is that 2.1 is for input to the pumpkin, Andrew's suggestion for the output from it. So "send end" was correct for both 🙂 ) Unless anyone advises to the contrary I'll follow Jensen for input and AndrewT for output.
For the future, though, I'd like to give Jensen's 2.4 a shot... This is the circuit ZM posted in post 2692. Is it too off topic to ask how you would figure out what to use for the values of the "added parts" if you had a commercial DAC you wanted to use this trick with?
Cheers
Nigel
For the future, though, I'd like to give Jensen's 2.4 a shot... This is the circuit ZM posted in post 2692. Is it too off topic to ask how you would figure out what to use for the values of the "added parts" if you had a commercial DAC you wanted to use this trick with?
Cheers
Nigel
jensen 2.4 shot - Papa's schm is simpler , omitting both 100K resistor and cap .
do you know how to measure output impedance of your DAC ?
do you know how to measure output impedance of your DAC ?
Zen Mod said:
By Papa's schm you mean the circuit you posted above in post 2693? I found this in the A75 article, but I haven't read through it yet. (Right now I'm ploughing through the Rane article on this stuff that AndrewT recommended....)
Actually, no, I don't think I do know how to measure output impedance... My guess would have been measuring voltage across a known load, or something like that.. I'm also guessing there is something on the passdiy site that'll help. (Reference?) Oddly, I expected figuring out the capacitor value to be the hard part, but apparently if I follow your suggestion I don't need to know this anymore... 🙂
Cheers
Nigel
njepitt said:
yup, that one .
measuring output impedance of any stage ( except output amp hehe) is pretty easy ;
in your case - feed your DAC with sine wave "music" either ditto from PC or from CD transport ;
if you have only DMM , it's important that you use sine between 400 and 1KHz
measure AC voltage on unloaded output and note it
put trimpot (2K2 to 5K is good enough) from output to ground ,connected as variable resistor (one leg to gnd , one leg to output , wiper to gnd)
measure AC voltage on output (to gnd) and turn that trimpot down;
stop when you have 50% of previously measured voltage (unloaded output ) .
disconect pot from out and measure it's resistance - it's exactly same as output impedance of your DAC out .
ZM,
OK, thanks. Seems pretty straightforward. (Apparently I had part of the idea...) Knowing this value presumably substitutes one of the resistors
Stupid question about the Pass A75 article... Figure 10 on page 12 (which is the circuit you posted earlier) shows two triangles; I presume one represents the source, which in the article is a preamp, but in my context is the DAC, but does the other represent the amp we're feeding, which in this case is the pumpkin? If so, then how would we connect R3 and R27, which appear to be feedback resistors? (Or did I misunderstand completely and this triangle is really an opamp?)
Thanks again
Cheers
Nigel
OK, thanks. Seems pretty straightforward. (Apparently I had part of the idea...) Knowing this value presumably substitutes one of the resistors
Stupid question about the Pass A75 article... Figure 10 on page 12 (which is the circuit you posted earlier) shows two triangles; I presume one represents the source, which in the article is a preamp, but in my context is the DAC, but does the other represent the amp we're feeding, which in this case is the pumpkin? If so, then how would we connect R3 and R27, which appear to be feedback resistors? (Or did I misunderstand completely and this triangle is really an opamp?)
Thanks again
Cheers
Nigel
