Why don't phonostages have balanced inputs?

[@heyrec]

you are great! this is one of the best explanations out there. After more than 25 years of cutting records for the industry I dare say. Wow.

[@cobar5342]

Very good video and to the point in an articulate manner.

[@net_news]

amazing video!! You are great bro!!

[@primoz.crncec.gramofon]

Great job! :)

[@michaelfidler8218]

Thanks! 😄

[@guillermomartin8248]

Thank you for the informative video! I am a bit confused though. I’m sort of a newbie to turntables but I have been in digital audio for sometime and always use balanced XLR connections with everything. That being said, I have a turntable now Pro-Ject RPM 5 Carbon, they state (Pro-Ject) that the wiring they have in the phono terminal can be used with their RCA > XLR (mini) connection to achiever a balanced connection with an MC cartridge (which I have); that being said, I can exchange my TT for a Carbon 9 RPM which has a direct mini XLR out to XLR in of a phono stage although the RPM 9 is about 1200 more. Are you stating that it isn’t worth it? Or that it isn’t worth it going XLR out from the phono stage to your preamp/processor?

[@michaelfidler8218]

Wiring balanced from the phono preamp can be worth it but a cartridge is a floating source so a balanced input just adds twice the noise power.

[@mfr58]

Great presentation. I would say though, that things may be somewhat different when considering moving coil cartridges in terms of noise pick up, given their much lower output. Rather than using electronics to create a balanced input, we can use high quality input transformers, thus overcoming the complexity and noise. You may object to the vagaries of transformers, but many audiophiles prefer them to high gain electronic input stages. You can of course use them with moving magnetic cartridges too.

[@michaelfidler8218]

I'd say a transformer (being a magnetically coupled device) represents a much greater risk in terms of hum pickup than any floating input you could think of, though. There's also the extra thermal noise generated by the winding resistances, making the noise figure with an MM input worse than a pair of relatively cheap transistors... Unfortunately, Audiophiles prefer many things that are sub-optimal, and we only need to cast our gaze onto valve amplifiers with 3% distortion or so at a few watts to confirm this! I doubt you can use a transformer for an MM cartridge with good results, as they have a very high impedance indeed at the top of the audio band, which would make a flat frequency response a very dubious proposition...

[@mfr58]

@@michaelfidler8218Yes, points all taken. However I think this highlights the split between spec hunting and musical enjoyment. Not that they can't coincide, but we can often be surprised when text book engineering doesn't give the most pleasing results. Whether "pleasing" is the most accurate by measurement or not, music is ultimately about emotional experience. I just listened to the review of your phono stage and it certainly appears impeccable.

[@ruffrecords]

A balanced connection does not require one signal to be the inverse of the other. The balanced signal exists only between the hot and cold. The ground is not a signal connector but just a shield. A balanced connection is one the total impedance of the hot connection is the same as that of the cold connection. Cheers Ian

[@michaelfidler8218]

It depends on the type of balanced connection. For a transformer balanced input you're quite right that the signal doesn't flow to ground. For an electronically balanced output and input there is some ground current as the ground is the reference on each side (before subtraction).

[@ruffrecords]

@@michaelfidler8218 I understand what you are saying but this is a popular misconception. An electronically balanced input is only interested in the voltage between its hot and cold inputs. Ground is not involved. Imagine a cartridge connected directly to the hot and cold inputs. No ground connection at all but it works. The point is that an electronically balanced input or output may well reference its outputs to it own analogue 0V but that reference is immaterial for signal transmission. Try connecting a battery powered electronically balanced output to an separate battery powered electronically balanced input. Just connect the hot s and colds. No ground connection is required.

[@michaelfidler8218]

@@ruffrecords If you connect a floating source to an electronic differential amplifier (like a single stage balanced input) it stops floating with reference to ground as the diff amp has a ground reference and unequal impedance in each arm. If you connect a ground referenced differential output to a diff amp then you get roughly the same voltage on each arm, whereas it appears lop-sided for a floating source... Kirchhoff's law says that current is going somewhere! The ground is important in any case as a floating source will have far more common mode electrostatic interference and noise of which a small amount will make its way past the CMRR of the input.

[@shaunjp2211]

Project x1b,x2b,x8b turntables and S3, DS3 phono stage fully balanced but also with option for RCA single ended.

[@rogerstaton5297]

There are many transimpedance phono stages now that offer current amplification rather than the normal voltage amplification they usually offer xlr connection rather than RCA phonos.

[@michaelfidler8218]

Yes, but those are actually marketing scams because the entire premise is flawed.

[@jedi-mic]

@@michaelfidler8218 do you mean flawed in the sense of current amplification instead of voltage?

[@kenpell2777]

I got your self effaceing humorous reference Micheal very nice😊

[@NackDSP]

I disassembled my Technics Q350 turntable and found the wiring was balanced all the way out to the RCA connectors. So there was no "ground" connection from the cartridge. The separate ground wire was attached to a few small shielding plates. There is a 3 dB increase in the input referred noise of a balance preamp vs. an unbalanced preamp using the same op Amps, but the line noise is now down with the noise floor of the other frequencies. The balanced input stage I built using LT1037 Op Amps show 80 dB SNR in LTSpice and are exceeding that performance in reality. The surface noise of the records I own are 20 dB above the noise floor of my balanced preamp. Many of the claims about record SNR are total BS and I suspect are based on 50 cm/s signal levels with massive distortion not the 5 cm/s where the distortion is 1% up to 5% for larger radius styli. With my balanced input the 60 Hz noise is at the same level as the noise floor of the amplifier. That the performance using a few inches of unshielded twisted pair wiring between the phono player and the preamp. There's no way I would go back to unbalanced. Performing the RIAA digitally is by far the best way to do it. Perfect channel to channel matching.

[@michaelfidler8218]

You can build an RIAA equaliser with channel matching as good as an analogue front end. 80dB SNR is physically impossible with two 3.5nV amplifier inputs (to make 5nV) + the resistors. Half the gain for balanced is BS. Full gain is required each amplifier side for a balanced input with the same output. The input signal from the cartridge doesn't magically double just because you connect it to a balanced vs single-ended input.

[@NackDSP]

@@michaelfidler8218 "Half the gain" Oh, of course you are correct. I got confused looking at the resistor ratios with the resistor shared by the two sides. When I include the RIAA high frequency filter the noise with out a record playing was measured to be 80 dB below the peak signal from a record I played. I don't know what the level was on that record. Maybe it's 15 cm/s ? Anyway. My balanced setup is working really well. Better than predicted using the LTSpice noise calculations. LTSpice predicted 78 dB SNR with a 3 mV input from the cartridge.

[@williamkobling8397]

Michael Fremer actually liked the Pro-Ject X8 which is a fully balanced TT and fully balanced phonostage preamp. I think I would believe him.

[@michaelfidler8218]

Might I remind you that the same reviewer has made a number of claims about mains power cables of a similar nature... You are, of course, entitled to believe what you like, but the objective evidence here is very clear.

[@asaholey]

Try downloading all Michael fremer needle drops and you can hear humming sound in every intro, outro. That guy is pretending to be an audiophile

[@marcbegine]

Pro-Ject Audio Design DS-3B with Ortofon MCQuintet Black S and Pro-Ject Audio Design Xtension 9 EVO, fully balanced in and Out (XLR)😎

[@michaelfidler8218]

OK - 3dB extra amplifier noise...

[@felixfranzen7578]

Hey Michael. Got a question for you. What's the overload margin of the MM Pro in mV's? According to Audio Science Review (who revieved and measured the MC Pro favourably) the Schiit Skoll clips at 154mV (but I guess that's at 1kHz). Will the MM Pro do better? Anyway, I use both hifi carts and DJ ones like the Ortofon Concorde MKII's. Some of those have an output in the 8-10mV range (as opposed to the 3.5-5mV of the average "hifi" MM cart). Will the MM Pro cope with that without transient distortion from specs of dust and such?

[@michaelfidler8218]

The MM Pro should be fine with cartridges up to 8.2mV (overload is 82mV at 1kHz), to give an overload margin of 20dB, but will outperform the Skoll in practice because it's much more linear at high frequency, right up to the point of overload. For something like the Concorde, which has an output of 6mV, you'll be absolutely fine with about 22dB of overload margin. I've not really seen any DJ cartridges with outputs over 8mV, so aim for about 80mV overload at 1kHz when I design things. If you know of something popular with a higher output than this at 1kHz I'd be interested to know?

[@ericlegall5688]

Hello there ! just watch your video, it is great :) I am looking at a Pro-Ject turtable and i was about to buy the new X2B (Balanced), i might as well buy the old X2 (without the 5 DIN plug) and go for a better phono cartidge instead ? Is that wright ?

[@michaelfidler8218]

Yes! Go for a better cartridge, hopefully with a fine-line tip. The balanced phono leads are a total marketing scam, for the reasons outlined. I recommend at VM540ML or Ortofon 2M Bronze (and upwards). I hope that helps, and if you follow my advice to put the money in the cartridge, then you won't be funding fraudulent practices, so win-win!

[@ericlegall5688]

@@michaelfidler8218 thank you very much for your answer, of course it is helping me :) Now I’m questioning myself on the pre-amp side. I am going to investigate your website and products 😊

[@michaelfidler8218]

@@ericlegall5688 good luck with your cartridge upgrade, in any case!

[@sc0or]

There is no chance for a groundloop from a “floating” cartridge to a phono stage imho. Other parts that could be responsible for that loop appearance have nothing in common with rca/xlr connection.

[@michaelfidler8218]

Still a better idea to use a separate drain/shield to the ground referenced conductor IMHO, though.

[@jedi-mic]

@@michaelfidler8218 is it worth putting a small capacitor say 0.22 Peco ferrets on the shield to ground? Would it make it more efficient and give less noise

[@zztop7000]

Your right turntable is still using primitive outdated rca cable. But high end turntable already using fully balanced output I think that there's alot of receiver or processor still don't have balance output. With balance is very expensive. My turntable still using RCA if I switch to fully balanced turntable it's going to cost alot of money. You'll also need a balance preamp and balance amplifier. The benefit of balance turntable is no more humming noise no group loop.😊

[@joshualewis3337]

What about moving coil cartridges though?

[@michaelfidler8218]

Same thing, but slightly different issues. There's no worry about cable capacitance, but cable (and therefore potential loop) length has to be kept super short otherwise hum issues will make themselves apparent quickly with the extra 20dB gain.

[@kenmicallefjazzvinylaudiop6455]

Bugbath!!

[@TrinitronX]

Any discussion of "Balanced" vs "Unbalanced" interconnects and "ground" or "ground loops" should have a preface regarding these terms and what exactly is meant when the speaker or author is using these words. In fact, pictures and diagrams can often be even better to clarify things, because as people often say, "A picture is worth a thousand words". Often due to the complexity of how things can be wired or how signals can be sent (e.g. differential vs. non-differential), the term "balanced" can be used in a way that conflates different concepts into one. This is especially true when using the term "balanced" to mean the classic XLR differential and inverted signal sending method, versus simply a set of transmission lines with "balanced" impedance to ground potential as it's corresponding pair, in other words with the same impedance as the other conductor or wire. In fact, an audio engineering expert named Bill Whitlock would probably disagree with even using the term "balanced" to refer to the classic XLR "differential" signaling interconnect, without first saying that it's "All about Impedances". Indeed, based on the origins of the term at AT&T Bell Labs, he would be correct. "Balanced" has always originally referred to the impedances of each +/- signal wire being balanced with respect to ground, and NOT referring to "differential signaling". Likewise, the terms "ground", "grounding", "bonding" and "ground loop" can get us into confusing language territory because even for electrical engineering majors, these terms and concepts are often not taught in a "real world" or functional sense, but rather in a mathematical and theory-based sense. For example: A common misconception is that all "ground" symbols on a circuit diagram (or a set of many diagrams) are at exactly the same "zero" potential, even in the extreme cases across an AC transformer or AC to DC power supply boundary. In fact, it's more like choosing an origin of a graph or coordinate system, due to Voltage being a differential measurement between two points. Often, two separate DC systems can have a non-zero voltage potential between their respective ground references. The "ground" or "ground plane" on a DC circuit can be a floating ground with no connection to earth ground or the AC mains "third prong" safety grounding system. Indeed, any electronics on an airplane or moving vehicle are floating ground reference points with respect to earth ground potential. Another example: a common myth is that we can simply drain any stray noise voltages by grounding everything, or by having "clean power" and good grounding. Perhaps the prerequisites for "grounding", "bonding", and "ground loop" concepts should be to watch Bill Whitlock's excellent presentations for AES (Audio Engineering Society) about these topics. (As an AES member these can be found in the online video archives in the "e-Library" website, while many slides and papers are available with a quick google search). For "balanced" vs. "unbalanced" and "differential" vs. "non-differential" signal interconnections, similarly the video from Audio Science Review titled "Understanding Balanced Audio" is one great resource (see video: kzbin.info/www/bejne/hGLPe3aCarR2rq8 ). Another excellent and more detailed resource relating to both "balanced" vs. "unbalanced" interconnects, "grounding" and "ground loops" would be Bill Whitlock's presentation for AES 2021 during the COVID pandemic, which can be found for free here on KZbin in the video " Bill Whitlock - Signal Interfaces Debunked - 4/27/2021" (see video: kzbin.info/www/bejne/p4q1maqkra2oj9E ). One gem of knowledge presented in this video was that improving CMRR by using "balanced" connections has next to nothing to do with the signal, but instead with the balanced impedance of the +/- lines. There is an example of visualizing this as a wheatstone bridge circuit which can help to conceptualize it. So, actually given this information... differential signaling would not be necessary to improve CMRR for a phono to preamp interconnection. As long as shielded twisted pair cabling is used, and the impedances of the circuit are balanced it should actually improve rejection of the common mode noise. Going over this problem in detail with diagrams is very helpful, even for a well-informed EE major! I know that I've found it immensely helpful in dispelling some common myths, and to describe the full picture of noise, "grounding", "balanced" interconnects & differential signals, audio noise, "balanced" impedance-matched wire pairs, electromagnetic interference, and common mode noise. All of this is to say: Great Video! ... and for those interested, mentioned above are some further reading and viewing relating to these topics, to get us all on the same page and to dispel some common misconceptions and myths.

[@michaelfidler8218]

You're quite right that there is plenty of confusion in this domain. More than enough to muddy the waters to the extent that there's plenty of hunting to be had for the usual snakes and cold-blooded slimy amphibians who make a living of pseudoscience in audio! Ideally, this video needs to be broken down, with images like you say. I'm planning to start automating a lot of my production process now so I can have time to jump onto the front-end and do this.

[@TrinitronX]

@@michaelfidler8218 Yeah, so much complexity for pseudoscience and even just simple language-based misunderstandings and misconceptions to hide in plain sight. I've seen many forum threads on this topic turn into arguments when in reality everyone might have agreed if the terminology, connection and circuit details were clear to everyone from the beginning. I'd love to hear what you think about the AES 2021 presentation video above, especially regarding the CMRR improvement from a "balanced" as in "wheatstone bridge balanced" type of interconnect from a phono cartridge (either MM or MC) to a preamp. Regarding the RCA to XLR interconnect for a phono cartridge... I'd also love to hear thoughts or see experiments about such an interconnect when done as recommended by Bill Whitlock (slide @ 1:21:30 in the video). I'd suspect that even simply using a shielded twisted pair cable wired as shown in his slide #67 would help when interconnecting an unbalanced RCA to "balanced" XLR yet even with shorted wires to pins 1 & 3 at the RCA end. Maybe even better if a 3-conductor STP cable adapter were to be made specifically for phono where shield and Low/- (pin 3) were kept separated, and on the RCA end the separated shield wire were connected to chassis ground and not to the outer RCA barrel conductor. In other words, a true 3-conductor STP cable and separate signal paths & shield all the way. Of course, depending on the source and receiver, one would have to verify that 3 conductors are indeed kept separated and the Low/- (pin 3) signal is floating with respect to the shield & chassis. Some gear does often connect the RCA receptacle outer barrel to the chassis ground. The final option is the one shown in slide 71, which was glossed over quickly due to time limits on the presentation, but revisited during the Q&A section. The answer touched on how a floating isolating transformer is also equivalent to the wheatstone bridge example, but with very high-Z (impedance). So the main idea was that this would make the other impedances at the sending end negligible towards impacting the wheatstone bridge's balanced state. To do this in a phono to pre-amp interconnect in the millivolt range may be slightly more challenging than in a line-level RCA signal as the example, but theoretically possible to gain the same CMRR improvements (especially for those budget turntables which choose to ground the cartridge's Low/- lines, creating a ground loop in the process).

[@TrinitronX]

@ 7:46 - Just a small bit of information to consider: Not all turntables are well designed with completely isolated tonearm to cartridge wiring. So while the point here may be true for well-designed turnables (and truly floating cartridges). Some entry-level budget turntables (even from reputable brands such as Audio-Technica) hardwire the cartridge's signal (-) lines to the chassis ground internally, thus creating a ground loop path soldered into the PCB. This is surprisingly common with entry-level turntables with a built-in phono preamp, whether or not a switch is included to "bypass" that built-in preamp. Often, this switch isn't even a true bypass and still includes some filtering and ground loop paths still in the circuit when the switch is set to "Phono" or "bypass" mode. Also, some cartridges have wired one or both of the signal (-) lines to the chassis / tonearm ground, giving another ground loop path if the 3rd prong safety grounding system is also connected to the chassis or tonearm. Some of these cartridges have either a disconnect-able tab to remedy the issue, while others do not and therefore the ground-loop path is hardwired permanently inside the cartridge. I posted some real life examples of this here: www.audiosciencereview.com/forum/index.php?threads/pro-ject-phono-box-ds3-b-review.51792/post-1869150

[@michaelfidler8218]

@@TrinitronX It really needs its own discussion thread on ASR. But to be honest when the wiring is lop-sided like this, or the shielding is going through the negative return then all bets are off and you'll get much more hum with a floating single ended setup than a balanced differential one.

[@stirer]

What are your thoughts regarding current injection phono preamps?

[@michaelfidler8218]

Either poorly thought out or a marketing scam I'm afraid, the cartridge inductance will pull the high frequency response down by about 0.5dB in the case of moving coil cartridges, and grossly in the case of moving magnet ones. The usual 'provides electrical damping of mechanical movement' is simply fraudulent IMO as when you calculate the mechanical energy of the stylus in a typical moving coil cartridge, shorting the output (current mode) only removes a fraction of a percent every second, so for the lowest frequency of 20Hz or so you get an electrical damping Q factor of 300! A typical flat frequency response requires a Q factor of 0.7 so it's clear this isn't the mechanism of damping (it's the cantilever rubber/lossy mounting material). Of course it sounds plausible which is why it's popular but the numbers don't work out and it's grossly inferior in terms of overall RIAA accuracy.

[@biketech60]

This is fine theory . How many balanced phono stages have you actually Heard ? Things in theory don't always align with practice . Moving coil cartridges inherently produce a balanced output .

[@michaelfidler8218]

The beauty of a scientific approach is that I don't need to hear something to know that it's going to have inherently worse noise performance and complexity. Magnetic cartridges inherently produce a FLOATING output. Whether is is 'balanced' or not is entirely relative to the way it's connected and doesn't offer any advantages if adequate shielding is used.

[@johnkarapalidis2361]

If you could add diagrams to explain it or photos would help

[@stirer]

Wonderful presentations. What are your thoughts about passive versus active preamplifiers?

[@michaelfidler8218]

Active is vastly better, no compromise between input impedance and output impedace, either of which is sure to cause trouble!

[@omanyaki402]

Good presentation…just wondering, and not argumentative, given your explanations what are your thoughts about turntables themselves designed as balanced - ie Project’s X2 or others? Thanks

[@michaelfidler8218]

I think it's a good idea to use an XLR connector instead of RCA + a binding post, however using a fully balanced input (instead of a floating one connected only on one side to the reference ground, as is the case for RCA) isn't a good idea as you get +3dB more input noise from the electronics straight off the bat. It may be a handy marketing invention to drive sales, but it's certainly not desirable from a holistic point of view.

[@ChickenPermissionOG]

just isolate the audio ground and shield it internally.