Mind you, a 45R cart produces ca. 0.87nV/rtHz noise.
To have a S/N several dB’s above 70dBA with cart connected, your preamp should have an equivalent input noise below 0.9nV/rtHz, assuming a 0.5mV@1kHz@5cm/sec MC cart.
Hans
To have a S/N several dB’s above 70dBA with cart connected, your preamp should have an equivalent input noise below 0.9nV/rtHz, assuming a 0.5mV@1kHz@5cm/sec MC cart.
Hans
In the shown cable image the preamp´s chassis and TT chassis are connected to Protective Earth not to analog ground.
Why should Input 2 be connected to analog ground (and not to the chassis) unless you want to compare Diff to SE.
In a balanced connection, to achieve a high CMRR, sender should have equal impedances and so does the receiver.
When connecting input 2 to analog ground, you will have an unbalanced SE connection.
Hans
The screen on normal cable - be that single core or dual core - offers no protection against LF electromagnetic ingress. A screened cable keeps the loop area between the signal and signal return very small and that's why you get less hum pickup than if you just run two separate wires that are not twisted together and have a larger loop area. Its a totally different thing at HF, where the screen acts as an electrostatic shield and you get good rejection of RF ingress. One of the problems Neil Muncy (RIP) solved back in the 1980s was the XLR 'pin 3 problem'. There was a lot of confusion as to what to do with the screen in an XLR balanced connection, with some saying you should only connect it to ground at one end. Muncy explained that both ends of the shield had to be connected right at the chassis where the connector was located. This made the transmitting equipment, the cable shield, and the receiving equipment a single enclosure to RF. For unbalanced connectors, good practice for enhanced RFI immunity is to take a small value cap (5-10nF) from the signal return at the connector directly to the metal chassis right where the connector is located. This diverts RFI to ground away from the input circuits and again, to RFI, makes the system more like a single enclosure. This works very well on phono stages where you have high gain and plenty of opportunity for the cable shields to pick up RFI. When combined with a few turns of the interconnect cable through a lossy toroid, the result is great RFI protection. Unfortunately, even with balanced input stages, RFI is a problem without these additional precautions because of layout and the fact that CMRR drops off at HF.
I'm using a DL103 in current injection mode (ie running into a near short) and have not detected any issues - seems that this is a very good alternative way to deal with MC carts.
BTW here is Hans's graph of cart output vs cart resistance vs amplifier noise (c.f. from the Richard Lee's MC Pream thread)
Regarding point I mentioned above:
3, Wiring topology (ifad had to invent a name for several subjects) floating- balanced- differential, wiring return path and wiring ground....
First of all I would recommend attached pdf "Grounding" from Rane professional to be read, if not done before , I digested it over and over many years ago, moved it into the practice and it is just correct; the shield is extension of the chassis, not signal wire.
Few people mentioned cart is floating source, not balance or differential, I think that is indeed more correct. However floating source needs differential input at receiving end unless we ground one side (grounding one side I see unappropriated).
Just to facilitate discussion , I think we can all agree on following definitions (writtenin my own words ) :
Floating source: an voltage - current source not referenced to ground or anything except 2 connectors it has, referenced to each other.
Balanced source: signal where 2 equal wires are used, one for supply and other for return of the signal and they both have the same impedance, but not necessarily the same signal. If interconnecting 2 units, 3rd wire is shield connected to chassis at both ends.
Differential Source; as balanced but 2 wires carry the same signal of opposite polarity, and still the same impedance
Differential input: and amplifier that amplifies voltage or current differences between 2 inputs
To few comments read in this thread, particularly @ Mark:
Might be I expressed myself in difficult way, also mixing words that I tried to define above; I think it is correct that "single ended" amplifier will be as good as differential, but only if it is not referenced to the ground.
In many (or almost all) "single ended" circuit diagrams ground symbol is used , but that does not need (and I think it should not) be connected to real ground (chassis, mains earth, power decoupling caps...) , than this is just negative input of differential receiver, and it works just fine.
To avoid this ground connection battery or as in next picture, photocell PS is needed, and all is all merry
Above picture is just example of MC preamp, it looks like "single ended", but where is says GND, this is not really GND, it is signal return and all is perfect. Floating source in, floating source out if you wish.
Another thing that might confuse in this picture above (as in many diagrams elsewhere) is RCA connector symbol at input. That necessitates connecting grounds (real dirty ones) between devices by return wire, aka shield. 3 pin connector should be there.
Here I made small sketch also to facilitate. For active devices I used FDA symbol, but it can be also circuit from picture above, As mentioned, GND is not GND if not grounded, it is just return path or - signal.
PS for U1 is battery, I drove symmetrical PS and middle can be taken as reference, effectively transferring floating source to more common differential variety. This can be done also at U2, leaving U1 as floating in, floating out. With battery power this unit is not needed to be ground referenced.
My preference is to put first stage (U1) at least inside the TT, and solder cartridge wiring directly on it, but output can be taken from everywhere, from arm wiring (as most common), after U1, after RIAA, after U2 (making TT an line source). For me it is only important that connection between TT and unit that follows is as drown,;3 wire; (+, - . and shield-ground)
3, Wiring topology (i
First of all I would recommend attached pdf "Grounding" from Rane professional to be read, if not done before , I digested it over and over many years ago, moved it into the practice and it is just correct; the shield is extension of the chassis, not signal wire.
Few people mentioned cart is floating source, not balance or differential, I think that is indeed more correct. However floating source needs differential input at receiving end unless we ground one side (grounding one side I see unappropriated).
Just to facilitate discussion , I think we can all agree on following definitions (writtenin my own words ) :
Floating source: an voltage - current source not referenced to ground or anything except 2 connectors it has, referenced to each other.
Balanced source: signal where 2 equal wires are used, one for supply and other for return of the signal and they both have the same impedance, but not necessarily the same signal. If interconnecting 2 units, 3rd wire is shield connected to chassis at both ends.
Differential Source; as balanced but 2 wires carry the same signal of opposite polarity, and still the same impedance
Differential input: and amplifier that amplifies voltage or current differences between 2 inputs
To few comments read in this thread, particularly @ Mark:
Might be I expressed myself in difficult way, also mixing words that I tried to define above; I think it is correct that "single ended" amplifier will be as good as differential, but only if it is not referenced to the ground.
In many (or almost all) "single ended" circuit diagrams ground symbol is used , but that does not need (and I think it should not) be connected to real ground (chassis, mains earth, power decoupling caps...) , than this is just negative input of differential receiver, and it works just fine.
To avoid this ground connection battery or as in next picture, photocell PS is needed, and all is all merry
Above picture is just example of MC preamp, it looks like "single ended", but where is says GND, this is not really GND, it is signal return and all is perfect. Floating source in, floating source out if you wish.
Another thing that might confuse in this picture above (as in many diagrams elsewhere) is RCA connector symbol at input. That necessitates connecting grounds (real dirty ones) between devices by return wire, aka shield. 3 pin connector should be there.
Here I made small sketch also to facilitate. For active devices I used FDA symbol, but it can be also circuit from picture above, As mentioned, GND is not GND if not grounded, it is just return path or - signal.
PS for U1 is battery, I drove symmetrical PS and middle can be taken as reference, effectively transferring floating source to more common differential variety. This can be done also at U2, leaving U1 as floating in, floating out. With battery power this unit is not needed to be ground referenced.
My preference is to put first stage (U1) at least inside the TT, and solder cartridge wiring directly on it, but output can be taken from everywhere, from arm wiring (as most common), after U1, after RIAA, after U2 (making TT an line source). For me it is only important that connection between TT and unit that follows is as drown,;3 wire; (+, - . and shield-ground)
As usual, my clumsiness, only after i post I read it to review. sorry!
Just to add, by definition cartridge is balanced source as both pins will have the same source impedance.
It is not differential as nobody guarantees that signals on 2 pins will be the same but opposite, and there is no 3rd pin to possibly prove that..
Cheers,
Drazen
Good point, how quiet preamp actually needs to be ? More quiet than cart noise, enough as one cant delete cart noise.
Apparently my existing preamp (post#32) is quiet enough for my Ruby2 cart, But discussion is good as there are quieter cartridges around...
Cheers
I have no (zero) hum on my unbalanced input phono pre with a DL103 MC cart and the volume on the line preamp set to max. The total gain from the MC input to the amp output is 94 dB. The speakers are LS50's (~84 dB sensitivity) and the thermal noise hiss with my ear in the speaker cone is barely audible. Wiring and arranging the grounding schemes to minimise loop area and common impedance coupling are the reasons for it being so quiet.
Here is a link to the recording of the noise
https://www.dropbox.com/scl/fi/de0z...C_MM.wav?rlkey=jjfoz6v49mmku4mxno6qt04bz&dl=0
I tapped the pickup arm a few times to demonstrate the gain involved.
Here is a link to the recording of the noise
https://www.dropbox.com/scl/fi/de0z...C_MM.wav?rlkey=jjfoz6v49mmku4mxno6qt04bz&dl=0
I tapped the pickup arm a few times to demonstrate the gain involved.
True. In previous dialog you indicated the following as an attachment stating "see attachment for balanced connection". The only point I was attempting to make was that the diagram only shows the requirement to "support" a balanced connection. In other words the input lines require an appropriate connection to the phono preamp in order to become in totality a "balanced connection".
As an aside, in the case of the GyroHead previously described each battery powered amplifier can be viewed inside the tube depicted in the above, having two input connections and two output connections, leaving the manner of connection as desired. The resultant magnified currents increases the signal to noise ratios in subsequent amplification stages, that in the development are currently open air breadboarded with minimal noise/hum.
I seem to recall that you are using a Denon 103R MC cartridge and that it has a lower impedance than the standard Denon 103. Do you happen to know what noise levels you are targeting or using for the input to your preamplifier/head amplifier. Is it much below 1nV?
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These discussions will go on forever because we have no real working definitions of "balanced" and "ground". Both terms really need to be shot in the external hearing undiffusor and replaced with a better model.
All good fortune,
Chris
All good fortune,
Chris
I can say how happy I am reading fantastic works from Hans and Bonsai on this subject:
This is must read from Hans and friends:
https://www.diyaudio.com/community/attachments/mm-paper-pdf.1161286/
@Hans Polak , I gave it first read (there will be at least 10 reads of this), article deserves half of cover page on some of bets magazines, I mean that!
Where did you get CH precision test LP from? Couldn't find it on internet. I think that is very useful for anyone playing with vinyl to have, if at all available.
One funny thing; while reading Richard Lee MC preamp article from Bonsai's site, and looking to original circuit, transistors names kind of rang some deeply forgotten bell in my brain; opened this box that I marked "smeče" or garbage - throw it away when I was in high school (but I never threw it away) , and inside are 4 reclaimed metal can BC214 transistors as originally used by Richard Lee, i don't have counterpart NPN's do. I will not use them, but just for fun...
This is must read from Hans and friends:
https://www.diyaudio.com/community/attachments/mm-paper-pdf.1161286/
@Hans Polak , I gave it first read (there will be at least 10 reads of this), article deserves half of cover page on some of bets magazines, I mean that!
Where did you get CH precision test LP from? Couldn't find it on internet. I think that is very useful for anyone playing with vinyl to have, if at all available.
One funny thing; while reading Richard Lee MC preamp article from Bonsai's site, and looking to original circuit, transistors names kind of rang some deeply forgotten bell in my brain; opened this box that I marked "smeče" or garbage - throw it away when I was in high school (but I never threw it away) , and inside are 4 reclaimed metal can BC214 transistors as originally used by Richard Lee, i don't have counterpart NPN's do. I will not use them, but just for fun...
Hi,
I agree, many time discussions oscillate before common ground is established. As I started this tread, I feel it is my call to try to reduce that and brought post #57 and #65, with aim to help streamlining otherwise excellent chat.
Pls look at these posts and if you wish make better, no issues from my side about that.
Cheers,
Drazen
Many thanks for your excellent efforts to mitigate the dangers of these abused terms. In recent years, I've become a radical, arguing against any use of the two terms that doesn't explicitly contain a very exact description of its meaning in that context. To have any meaning at all, the description needs to contain details about both source and receiving impedances both relative to each other and relative to some imagined signal ground, and the receiving end's relative sensitivity to differential vs. common-mode signal.
The fact that more than a Century into this we still conflate all these different conditions allows us to misinterpret each others' thoughts so easily. I argue that we should just say No to "balanced" and "ground" until a better education spreads.
All good fortune,
Chris
The fact that more than a Century into this we still conflate all these different conditions allows us to misinterpret each others' thoughts so easily. I argue that we should just say No to "balanced" and "ground" until a better education spreads.
All good fortune,
Chris
Ha ha ha, cant agree more with you 🙂 !
I think , as posted above, that Rane article on grounding must be learnt by hearth.
Where I'm radical is that I think if there would be single person that invented brilliant RCA connection, should rot in jail forever. So much damage done by this brilliant "invention" that it is impossible to even grasp and idea of its magnitude. Just imagine what would the world be if DIN 5 pole is main connector for everything consumer related, with XLR as alternative, would we then have so much discussion?
Firstly, Hans and Bonsai are extraordinary contributors. I admire their work.
Not sure about the above Drbulj. There are countless elements that go into decisions in the manufacture of products, particularly parts/labour costs. Going balanced can double those costs that consumers are unlikely to accept (unless good copy exists to espouse the universal benefits to ones meaning and particularly pleasures of life of course... perhaps being delivered by a well-balanced socialite).
It seems true that any additional components to a network that supports balanced always has negative consequences to being equal to a "straight wire with gain" . This is to say that the positive benefits of balanced interconnects between networks/components can be easily undone by the electronics used to send/receive those signals. In general op-amps can be viewed all having some character (as countlessly reinforced in this site).
Unless the object is to voice the overall sound (a condition that appears generally necessary for experienced designers) it is a shot in the dark what the sonic result will be for most networks. This is why I try to avoid complex networks if possible, rather instead try to work around them by some understanding of the cause and mechanisms of potential problems that "balanced" networks are being used to solve . This is not to suggest that I have any deep understanding of grounding and shielding techniques.
Not sure about the above Drbulj. There are countless elements that go into decisions in the manufacture of products, particularly parts/labour costs. Going balanced can double those costs that consumers are unlikely to accept (unless good copy exists to espouse the universal benefits to ones meaning and particularly pleasures of life of course... perhaps being delivered by a well-balanced socialite).
It seems true that any additional components to a network that supports balanced always has negative consequences to being equal to a "straight wire with gain" . This is to say that the positive benefits of balanced interconnects between networks/components can be easily undone by the electronics used to send/receive those signals. In general op-amps can be viewed all having some character (as countlessly reinforced in this site).
Unless the object is to voice the overall sound (a condition that appears generally necessary for experienced designers) it is a shot in the dark what the sonic result will be for most networks. This is why I try to avoid complex networks if possible, rather instead try to work around them by some understanding of the cause and mechanisms of potential problems that "balanced" networks are being used to solve . This is not to suggest that I have any deep understanding of grounding and shielding techniques.
Hi Hierfi,
Thanks for comment, I appreciate but don't fully understand what you meant on all subjects. To best of my understanding:
Again, balanced does not mean both wires carry same signal, just that they are both of same impedance and used just for signal, not for shield and grounding as usual with RCA.
"Voicing" reproduction equipment (and media like LP when they are edited for cut) by commercial companies is in my view bad for customers (us) and absolutely not necessary. Besides that is bad for artist too as we don't listen what she-he wonted to present us! All together leading to chaos of misunderstanding and dissatisfaction, all together bad for audio reproduction. Best example is so called "loudness wars" in LP pre-cut editing.
Besides balanced interconnections are used throughout professional audio chains that make media that we listen, (there is no single ended wires there except in very very rare occasions) and that is with good reason. And that reason is not only famous studio noisy environment. Even I admit that modern studio is today digitalizing everything as soon as possible and only bringing back to analog if they want to make Vinyl out of it. It is sad truth that most of the material on vinyl that we listen was zeros and ones before, but at least they cut it from high res masters. (exception being audiophile pure analog records, but that doesn't count for me as I don't listen to audiophile records, but real music.)
Suggest you too study Rane paper on grounding and inter-cons
PS, recently I racked big studio that company shoot down, and my garage is full of Neutrik XLR's (hundreds of them and km of cable) I have not one single RCA cable from there. And that was TV studio, not even music strictly.
Hope I got you right, but please don' offend if I missed the point somewhere.
Cheers,
Drazen
Thanks for comment, I appreciate but don't fully understand what you meant on all subjects. To best of my understanding:
I argued in post#25 that cost of Phono preamp (if DIY) is diminutive in relation to cost of playing vinyl at home, all cost accumulated even if doubled for balanced will not exceed cost of 4 new LP's, so it is worth any penny, because there are not many pennies involved.
I only insist that both "straight wires" are treated with same care and love, because both signal and return are signal, post #65. Typical pro balanced drivers and receivers are not needed here (neither are always used in studio gear, this is more for stage machines with 100's of meters of cables) . Talking SSM2141, 2143 and such, we can do without them and remain balanced.
Again, balanced does not mean both wires carry same signal, just that they are both of same impedance and used just for signal, not for shield and grounding as usual with RCA.
I don't have intention to voice anything, just to reproduce accurately what the artist voiced.
"Voicing" reproduction equipment (and media like LP when they are edited for cut) by commercial companies is in my view bad for customers (us) and absolutely not necessary. Besides that is bad for artist too as we don't listen what she-he wonted to present us! All together leading to chaos of misunderstanding and dissatisfaction, all together bad for audio reproduction. Best example is so called "loudness wars" in LP pre-cut editing.
You say less is more. generally OK but I think not always, one wire extra needed to make balanced interconnection is not much more, but common sense. also that I tried to emphasize in post #65. (The same subject in second quote- answer above)
Besides balanced interconnections are used throughout professional audio chains that make media that we listen, (there is no single ended wires there except in very very rare occasions) and that is with good reason. And that reason is not only famous studio noisy environment. Even I admit that modern studio is today digitalizing everything as soon as possible and only bringing back to analog if they want to make Vinyl out of it. It is sad truth that most of the material on vinyl that we listen was zeros and ones before, but at least they cut it from high res masters. (exception being audiophile pure analog records, but that doesn't count for me as I don't listen to audiophile records, but real music.)
Suggest you too study Rane paper on grounding and inter-cons
PS, recently I racked big studio that company shoot down, and my garage is full of Neutrik XLR's (hundreds of them and km of cable) I have not one single RCA cable from there. And that was TV studio, not even music strictly.
Hope I got you right, but please don' offend if I missed the point somewhere.
Cheers,
Drazen