Dr. AIX's POSTSHD-AUDIO

A Power Cable Reality Check

I know, I know. Talking about cables is a sure fire way to start a protracted — and unruly — discussion among audiophiles. The subjectivists write flowery prosaic descriptions while those of use who prefer to trust facts and science report the science and move on. That regular posts about cables continue to appear on various Facebook audiophile group pages shows just how unsettled the topic remains among the uninformed. Yet here I am writing another blog on cables — power cables — to be exact. Is there really anything left to be said?

The catalyst in this instance is a recent review I read over at Positive Feedback, a site that features the motto “A Creative Forum for the Audio Arts” — creativity being the key word in that phrase. My reaction to many of the articles/reviews I’ve found on this site confirms their tilt towards the creative with a total disregard for the facts. But it was the review of the Cardas Audio Clear Beyond Power XL cable that eclipsed anything I’ve read for quiet a while. And guess who authored the review? The same gentleman that booted me from the Los Angeles and Orange County Audio Society last year because I dared challenge his unwavering support for the myth of power cables with documentary proof during a meeting here in SoCal! Click here if you would like to read that very popular post. More about his ridiculous review in a moment…

A few days ago I had to remove my Oppo BDP-203 from the rack and I happened to notice that it had a couple of screws bouncing around inside. As a former electronics technician and builder of more than my share of HeathKit products (receivers, guitar and amplifier, test equipment etc.), I’ve always enjoyed peeking inside audio gear. I’ve done a few mods on another Oppo player and a power amplifier in the past, so simply removing a few screws would be a piece of cake. However, inspired as I was from reading Bob Levi’s effusive prose in the PF review (“A liquid elegance and fleshy musical beauty emerged from a previous coolness and thinness.”), I decided to take a look — and some photographs — at the cabling inside the IEC power connector on the rear panel of the Oppo. See below:

The IEC power connector and three cables connecting to the power supply of the Oppo 203

I’ve been through this exercise before but let me restate the facts once again. The power reaching your duplex outlets comes through your home wiring through 12 or 14 gauge copper Romex wire depending on the amperage required (usually 20 or 15 amps) and costs about $.22 per foot. And inside your equipment is more 12 or 14 gauge stranded wire — generic wire that probably costs about the same. Designers of expensive IEC power cords would like you to believe that the 6 foot piece of cable they sell you which may contain “hundreds of the purest copper strands, each and every strand is coated with single poly nylon and only touch each other electrically at the final connection point” is going to magically transform the analog — or digital — signals passing between your components. For someone to claim that power cords “often make extraordinary differences” in the fidelity of your system is like saying that delivering that cord in a velvet bag inside of custom crafted box with dovetail joints has an impact on the sound! It’s just crazy! And anyone that would write such a thing and any website that would publish it should have their “bona fides” revoked. I know I wouldn’t trust anyone that would write something so ridiculous — and easy to prove incorrect.

That’s what I did with a very expensive power cord that a gentleman sent me some years ago. I used the regular IEC power cord recommended by my friends at Benchmark with their DAC 2 HGC and then swapped it out for the $3000 cord, which did come in a velvet bag inside a wooden box. I captured the analog output when using both cables and did a null comparison. To the utter amazement of the vendor in Atlanta, they both produced exactly the same output. Now some high-end audio manufacturers would have you believe that if two signals are identical that they could produce different sonic signatures — but that’s also utter nonsense!

I guess if you’ve got an extra $3000 dollars that’s burning whole in your pocket then throwing it away on a single 6-foot power cord is up to you. But if improving the fidelity of your system is among your priorities, then save your money and ignore the recommendations of people like Bob H. Levi and websites like Positive Feedback.

The Cardas Audio Clear Beyond Power XL – Photo courtesy of PF

Feel free to read the review yourself. Every paragraph contains prime examples of why audiophile “experts” are not always the best sources of information and why audiophiles as reviewers is also not a good idea. Here’s a few gems from the review:

“Top-tier power cords are the best way to tweak a state-of-the-art system for maximum realism and definition. After tube rolling, cable selection and matching, suspension tuning, final equipment selections, speaker adjustments, and room acoustics, you may not quite have that timbral naturalness and background blackness that brings the system to life. For that final adjustment, try different power cords to bring out those important nuances”.

It’s actually hard to read paragraphs like the above without laughing out loud — yet many audiophiles accept these fantasies as facts.

“The Cardas Audio Clear Beyond Power XL in combination with the V12 Amplifier yielded one of those unforgettable, you-have-got-to-be-kidding-me moments an audiophile never forgets! The XL was easily 25% more detailed, produced a blacker background, was smoother than my already smooth reference, and captured timbral realism beyond my ability to describe in English. Like the fictional Red Violin, maybe George has captured DNA and infused it into this power cord such that it reveals not just a great recording, but a great performance just a few feet in front of you. I had to remind myself, this was just a power cord change, not an additional super widget component. The resulting system improvement in realism and mellifluousness with just one Cardas Audio Clear Beyond Power XL was fantastic and unassailable”.

One final anecdote before I post this blog. Before I was kicked out of the LA & OC Audiophile Society (for telling the truth about cables!), I attended one of their regular monthly events. Bob was always very kind to allow me to sell my book (Music and Audio: A User Guide To Better Sound) during meetings. He even gave it a very positive review but I’m guessing he didn’t read the chapter on cables. Anyway, a local vendor was doing an A|B comparison. He was elevating the hard drive attached to his laptop with an isolation pad ($250) between playing back the same digital music selection. He went back and forth a couple of times to make sure everyone could hear the difference (there was none!). I was sitting close to Bob along one side of the ballroom and heard him announce to a couple other members of the society what a huge improvement he experienced with the isolation pad in place. Only he made that pronouncement when the pad was removed NOT in place — he got it exactly reversed.

My father once taught me that integrity is something that is very difficult to establish — but very easy to lose. How much integrity is present in audiophile reviews? From my perspective — not very much.

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

My brother Lee and his beautiful family.

My younger brother is in need of some help. This isn’t the place or platform to relate the details of his current situation but I know some of you might consider making a contribution to the GoFundMe campaign I started for him once you read the narrative I authored. In fact, since I posted this a week ago, many readers have given generously…thank you!

I wouldn’t make this appeal if I didn’t feel his circumstance was compelling and the person worthy. If you want to read more, please click the link below and consider making a contribution.

To thank anyone that makes a donation of $100 or more, I will send a signed copy of my “Music and Audio: A User Guide to Better Sound” (with Blu-ray Demo disc) AND a FREE copy of the latest AIX Records sampler— a $25 value. If you contribute $50 – $100, I’ll send the eBook, downloadable files, and the AIX sampler. Finally, for a donation of $25 – $50, you’ll receive the eBook and demo files.

I will cover all shipping expenses for domestic orders. International shipping will be additional.

Click here to be taken to the GoFundMe page.

Please do not share this link. Thanks for your consideration. And thanks to those that have generously contributed to the GoFundMe campaign!

Dr. AIX

Mark Waldrep, aka Dr. AIX, has been producing and engineering music for over 40 years. He learned electronics as a teenager from his HAM radio father while learning to play the guitar. Mark received the first doctorate in music composition from UCLA in 1986 for a "binaural" electronic music composition. Other advanced degrees include an MS in computer science, an MFA/MA in music, BM in music and a BA in art. As an engineer and producer, Mark has worked on projects for the Rolling Stones, 311, Tool, KISS, Blink 182, Blues Traveler, Britney Spears, the San Francisco Symphony, The Dover Quartet, Willie Nelson, Paul Williams, The Allman Brothers, Bad Company and many more. Dr. Waldrep has been an innovator when it comes to multimedia and music. He created the first enhanced CDs in the 90s, the first DVD-Videos released in the U.S., the first web-connected DVD, the first DVD-Audio title, the first music Blu-ray disc and the first 3D Music Album. Additionally, he launched the first High Definition Music Download site in 2007 called iTrax.com. A frequency speaker at audio events, author of numerous articles, Dr. Waldrep is currently writing a book on the production and reproduction of high-end music called, "High-End Audio: A Practical Guide to Production and Playback". The book should be completed in the fall of 2013.

44 thoughts on “A Power Cable Reality Check

  • I’d like to know what’s inside that bulge just behind the plug.

    Reply
    • Admin

      It’s an RF filter.

      Reply
      • Wouldn’t that be better placed near the device end of the cable?

        Reply
        • Admin

          There’s no need for them at all. The power supply does all the appropriate filtering inside the component.

          Reply
      • Cosga

        audiophiles are the biggest mugs out there, along with high end wine snobs who also fail routinely in demonstrating their supposed superior sensing skills when blinded.

        My fringe has power conditioners, power cords, connectors that look like umbilical cords from a spacesuit.

        His stereo does sound good but then it would, given the 5 grand speakers. It could possibly be even twee if he’d invested the 2k he put into the pointless crap into even better speakers.

        Reply
  • Soundmind

    I can’t believe this argument seems to go on without end. It’s almost like a crusade. Nobody is going to convince anyone on the other side. Don’t confuse them with the facts, their minds are made up. Why do people keep wasting time on this?

    Here are the facts. Among other things I design and build plant facilities electrical power distribution systems. Many are for laboratory buildings using state of the art equipment so sensitive it’s beyond belief, One machine photographed atoms. Electron microscopes. Mass spectrometers. HDA head positioning mechanisms for high density hard drives, and on and on. Must have been way over a hundred million dollars worth over the last 40 years. If I don’t have the right answers then who does? I have access to every wire manufacturer and distributor in the United States. I’ve specified, bought, and installed enough wire to stretch from the earth to the moon and back many times over. All different kinds. And in all that time, with all of that equipment there was not one time I can recall when THHN/THWN properly sized compromised any of it, not even one single time. So why is this rat shit audio equipment so special? If it really matters that’s proof enough for me that the equipment itself is no damned good and is sufficient to reject it. Its power supply is junk.

    BTW, I’ve also installed a lot of IG systems at customers’ insistence and even wrote a spec for accepting testing and trouble shooting these systems but neither I nor any electrical contractor or journeyman I met ever saw a problem that installing IG fixed. The problems if there were any were always somewhere else.

    Reply
    • Sincere thank you to Prof. Waldrep, Soundmind, D Griffin, Benchmark engineers, and others grounded in reality.
      Your words of wisdom have helped me understand the need for being grounded in science. You are teachers of the truth.
      Regards,
      TL

      Reply
  • Geoffrey de Brito

    So the argument is that if no measurable difference can be detected, no difference exists? And, that those who report hearing a difference… are either deluded, liars or susceptible to some kind of mass delusion?

    So do I have that right, is that an accurate “bottom line” for the argument that power cables make no difference?

    Reply
    • Never seen 4 foot of religion fix a 100 miles of sin.

      Reply
      • Eric Thomas

        The sonic properties of any component were honed using known properties. The idea that the power cord, with it’s most basic of those properties should be replaced with something else is just flawed reasoning on it’s own. I once beefed up the cable on an HTR-5730 entry level Yammy and despite increased resolution the midrange slapped me in face. Oh well, it was back to that puny power cord ya know?

        Reply
    • Alan Stephens

      Yes, Geoffrey, you’ve got it exactly correct. Also, uneducated in electricity and electrical engineering — and possibly ignorant about science in general — as well as a burden on those of us who like to engage in reality based discussions. And finally, suckers, at least insofar as the people who are happy to take your money for these cables as concerned. This is possibly not the answer you were looking for, but, ‘bottom line,’ when you’re right, you’re right, so I’m giving you the props you’ve earned.

      Reply
      • i’m open to the possibility that there *might* be audible differences with certain components that can’t be measured, but if there are actually audible differences, then it can be detected in a blind test – especially since the differences are ALWAYS described as “enormous”, “huge”, “mind-boggling”, “jaw-dropping”, etc., but when the people who express these views then take a blind test, and fail spectacularly, they either blame the test procedures, or they change their statement to “well, it was just a very subtle difference” (no longer “jaw-dropping”), and apparently this can’t be detected in a blind-test (since it’s always the fault of the carpenter’s tools that the house collapsed).
        In the specific case of power cords, I simply can’t see how it could possibly make any difference – I’ve tried out two expensive cords myself, on the insistence of sellers, and heard no difference, but I’m always happy to do a blind test along with someone who believes he can hear a difference, but no one is ever willing to do it.
        The website Home Theater Hifi reported a blind test between a Nordost power cable and a stock one done by an audiophile society, and people couldn’t tell them apart.
        Archimago also did measurements of an expensive power cord as well as a stock one and found absolutely no difference.

        Reply
  • Some can hear changes and some can not. It also takes a well set up system in a a good acoutical space. And it can be measured as noise on the line. But hey if you can’t hear s Chand consider yourself lucky….you’ve save yourself thousands!

    Reply
    • Admin

      You say that some listeners will hear changes and some won’t with different power cords. What changes do you hear? And how good does you system have to be to make them audible? Science, physics, and electrical engineering argue against your position. If the signals coming out of an audio component are identical, they will produce the same sound. Any noise on induced on the power line is properly filtered at the power supply of the device and doesn’t end up on the audio bus. Spend whatever you want on crazy expensive cables, that’s your choice. But I know professional studios and engineers don’t bother with that stuff.

      Reply
      • I’d say any equipment affected by the choice of power cord (of sufficient current rating) is defective.

        Reply
        • Admin

          I agree. A properly designed power supply only requires what a simple power cord can deliver.These expensive power cords are a complete fraud.

          Reply
      • Very good well designed power cables can be like a component upgrade. Your response states the VERY reason power cords make a difference. The audio signal will sound the same or very close if its measured the same, but herein lies the rub….they dont’ measure the same and sound different. Most of the time the one with less noise will sound better. “What changes do you hear?” you asked. For my ears and my brain(we all hear in diverse ways) I notice a blacker background, easier to listen to music, better timing, and clearer highs. It is just an overall better listening and more relaxed experience. Even the best power supplys do not filter all noise. So why not feed that power supply with a good clean start. If no one could hear a difference how in the world are all these cable companies staying in business year after year. Listen with your ears and ignore the measurements.

        Reply
        • Admin

          Marc, if you want to believe that you hear “blacker background” and “better timing” with expensive cables AND you have the funds to spend on these products, then you’re certainly entitled. Yes, the best power supplies do filter all of the noise AND they deliver the required DC voltages (plus and minus) to all of the internal components in the device. You ask why these cable companies are staying in business…it’s simple. They buy expensive ads in the audio magazines, give free products to reviewers, falsify their demos, get bogus testimonials, and cater to the editors of the major publications. It’s a rigged system and with people like yourself continuing to swear that science, physics, and engineering doesn’t apply, it’s going to continue. That I was able to determine that the $1.50 IEC cable produced the identical (not close…but identical) signal as the $3000 custom cable is proof enough for me. Professional studios don’t use these products (I have 9 state-of-the-arts rooms in my building), so why would anyone consider spending thousands of even hundred or even tens of dollars on a short stretch of power cord? It makes no sense to me. One vendor of expensive cables told me it costs between $15-50 for the parts that go in to his $500 cables. But he has to spend $200 per cable (on average) for advertising and promotion. If you really want cables that “look great” by the components and get out your soldering iron. Power cords are a complete fraud and do not affect fidelity at all.

          Reply
          • Well good for you if you can’t hear the difference, like I said you will save a lot money on power cords. But you have no place tell me what I or thousands of others hear. We ALL hear different! Myself and several others I know have picked cords out in an A/B ABBA etc…at a 100% success. Rigged? That’s just ridiculous! “Yes, the best power supplies do filter all of the noise AND they deliver the required DC voltages (plus and minus) to all of the internal components in the device.” Another ridiculous statement. There’s no perfect solution for noise-free power. Plain and simple. So yes, I will continue to listen and evaluate power cords, interconnects, speaker cables, components, speakers, etc. and base my purchase decision on what I hear.

          • Admin

            Marc, you’re entitled to believe what you want. It’s a free country and you and your golden-eared friends can continue to support the nonsense offered at outrageous prices by the hucksters. Using your ears should be balanced with a basic knowledge of technology and facts. It never ceases to amaze me that individuals such as yourself refute basic science and electrical engineering principals. But that’s the way the cable companies want it I guess…they’re smiling all the way to the bank. They’re advertising and the support of the major magazines seems to be working. Enjoy your cables.

          • Very similar to discussions with a ‘flat earther’, eh?
            Another version of “don’t confuse me with the facts”.

        • Ignore the measurements?

          Sure…..why not? And while you’re at it ignore the price and the overall gain in fidelity (arguably no gain AT ALL).

          Additionally, ignore the fact that the the power signal is carried to the wall outlet via plain old Romex wire, either 12 or 14 gauge and the fact that the truly Hi Fidelity audiophile amplifiers will ALL have great conditioning circuitry in their power supplies….which is why that hardware costs in the thousands of dollars in the FIRST place. Duh?

          I’m sorry (not really) but I cannot wrap my brain around how a simply six foot 12-14 gauge power cable can condition ANY wall plug supplied voltages / currents with NO active components built into said cable. Sure the power cable might have an RF choke or two built into the sealed ends of the power cable but I said ACTIVE components, NOT passive. If you don’t know the diff, look it up.

          One caveat…..if a truly active high current POWER CONDITIONER is placed in between the wall outlet and the amplifier, THEN it might behoove audio purists to use a high dollar power cable between the power conditioner and the Hi-Fi amplifier.

          Next time someone tells you they can hear the diff, challenge them to a blind listening test. You can figure out the rest. It’s the only way to truly tell if your ears can tell the diff or not. And if you think YOU can tell the difference, ask a friend to help you do a blind test. If you can consistently tell the difference between a high dollar power cable and a $5 power cable from Wally World, then that $300 power cable is worth it to you.

          I’ve done the double power test using my Marantz Model 30 whilst connected to my two Bowers & Wilkins 702 S3 speakers. I purchased the AudioQuest NRG-Y3 from Best Buy and did the manufacturer’s “break-in” period of two weeks before doing the blind listening test. Some might argue the Marantz isn’t HiFi enough to hear a difference but I’d maintain that if they’re THAT certain they CAN hear a difference in their system with their own ears and it was a blind test, then by all means, go with the expensive cable. I returned mine, thankyouverymuch.

          Bottom line, if you think it’s worth it then again, buy it. But I’d add to your comment about “ignoring the measurements”. If I ignore the measurements, then a $100 amplifier will be just as Hi Fidelity as a $10,000 amp.

          Ignore the measurements…………..wait, whaaaaat?

          So, the earth IS flat? So, we really didn’t go to the moon?

          Reply
      • Jaap Miedema

        I had a Shanling SACD player that I put a silver power cord in, with a ferrite ring and it made a very audible difference noticed by myself and my friend at the time. I isolated it to the use of the ferrite ring mainly. You can’t argue with what you hear, especially if someone else hears the effect as well. It was inargueably different (better) with this power cord and the SACD T200 I think it was called.

        Reply
        • You can imagine what you want when listening to expensive power cords but the facts remain. There is not audible change with a power cord.

          Reply
  • Marc

    And one more thing, if you truly believe this is fraud (which I would be careful using that term lightly) why don’t you do you civil duty and report it to the Federal Trade Commission and protect us dum deaf audiophiles.

    Reply
    • Admin

      I actually have been confronted on the legal front a couple of times and when my attorney told those representing a couple of expensive cable companies we’ll see you in court so that they could prove that power cords affect the sound, they all backed off. Funny. If they were so confident, then why wouldn’t they want to proceed?

      Reply
      • Ha ha! I hadn’t heard that story before, mr. Waldrep. I knew that you had been threatened with a lawsuit when you exposed the falsified power cord demo, but I hadn’t heard that your attorney had said “see you in court where you can prove the audibility of your cables” to the manufacturers. That’s a great story :-)!

        Reply
      • GREAT story Admin! I love it.

        Reply
  • Marc, no offense but I think what you are hearing is expectation bias, the AC power travels through tens of feet of regular copper wire from the fuse box to the wall socket, when it goes through the transformer it’s isolated completely from the mains supply, that’s how a transformer works. Now if you upgraded the components on the other side of the transformer you would have a point. But it’s your money, be happy with what you buy.

    Funnily enough I ran my phono stage on pure DC from batteries at one point and neither myself or golden eared friends could tell the difference, between the batteries and the AC supply, go figure.

    Reply
  • It is possible that some things that were not measured could have audible effects in some cases. Some cords match some equipment better than other whether because of impedence or some voodoo about induced field along parts of the chord. There could be differences in the case of some equipment or “noisy” environments and not in others. Most of the time my golden ear doesn’t hear a difference I can ascribe to a cord. But in one case changing up an ac cord to a cheaper cord sounded better, to my ear. I remember Frank Zappa , may he rest in peace, once did a concert mostly recorded on cassette, which of course, with all due respect to Ella and Memorex, sounded nothing like the real thing to his ear…and almost nobody noticed. I don’t pretend to be an engineer, but i do trust my ear and in some cases, for whatever reason, there is a difference. it’s just not because it’s cryo-treated quantum-wound audiophile-blessed.

    Reply
    • Of course, you are entitled to your opinion but science has established the facts in the matter. Unless you have really poor cables or problems with your incoming power, expensive, exotic cables have no effect on the fidelity of your system. A Belden, Mogami, or Canare cable will do the job just as well as SR, AQ, and Nordost.

      Reply
      • Unfortunately, you seem to have been convinced about the merits of cables. I have a $250,000 mastering studio and we used Belden and Canare cables throughout. There is no reason to spend money on Nordost or any other “audiophile” cables. You just have realize that professionals do not subscribe to this nonsense.

        Reply
        • AdminPLUS

          I love how all these people have 250k studios and 9 “state of the arts” in their buildings and yet come on here to comment about ahit they probably haven’t even tried but say they have lol.

          Reply
  • Dr. Yves St Laurence

    I could get from point A to B with a cheap 1966 VW Beetle or a motor scooter.
    But I like my Mercedes 450SL far better. Costs more, but so what?

    Reply
    • The difference between a cheap 1966 Beetle and Mercedes is not merely the added cost. When I first sat in a BMW and took a drive, it was a revelation compared to the Chevy Vega or Honda Civic I owned previously. There was an obvious difference. With power cords, pricey HDMI or digital cables and interconnects, and even speaker cables, there are no perceptible fidelity improvements. You spend more money without any benefit unless you love the look and feel. I have a Fisch power strip and power cords as well as Audience and Cardas speaker cables at the studio. They given to me. They make not difference in the sound coming from my speakers. This is in my $250,000 mastering room…my gear is “revealing” enough. Spend crazy money on cables if you have money to flush down the toilet but your comparison doesn’t hold up.

      Reply
  • John Kennedy

    The unspoken premise inside a lot of these pro-high-end-cable arguments is that the proponents possess golden ears and that they hear things that we mere humans cannot. I know there are quite a few people with better hearing than myself (mostly females), but none can defeat my argument that I like the way that my stereo sounds with basic cables. Even I can tell the difference between the sound quality of my tuner compared to the sound quality of my cd player! I just don’t think it’s the cables. Sometimes, it’s the weather.

    Reply
  • Jacob Miedema

    There is an effect of a ferrite ringed silver power cable on Shanling T200. How audible the difference is depends on the electrical item itself as well I have found. This cable wasn’t overly expensive and bought on ebay (Chinese). Both my friend and myself were surprised by the difference the cable made, which proved to be mainly due to the ferrite filter.

    Reply
    • There is no difference in the sonics of a system using an inexpensive IEC power cord or an expensive one, period.

      Reply
  • Paul at PS Audio is saying he includes courtesy cable meant to be immediately replaced. I have 600 w monoblocks and the well know manufacturer told me “any” 14 awg cable does the same thing.m

    Reply
  • All sorts of cable differences are crystal clear to those like myself, who have spent an entire lifetime as a permanent member of a symphony orchestra, where we listen most intensely in order to be precisely together and in tune with each other. Add to that the 10,000 hours (no exaggeration) of practising and LISTENING needed just to get to the starting gate! No microphones, no loudspeaker, no digital conversion, just the sound of real instruments as nature intended. I don’t care if you can’t measure it, if I can hear it its Real! There’s plenty of science where measurements are unable to keep up with what we can see and hear – astronomy for example, where new theories regularly replace old ones. Even Einstein’s theories are found to need updating in order to explain new realities.

    Reply
  • You said “Science has established the facts” – you should know that Science is not about what you (think) you know, but about what you do NOT know. Science is about trying to understand something – and here is something that you don’t understand because either 1) your equipment is not sufficiently revealing or 2) your ears are not sufficiently sensitive or experienced. SHAME on you for deleting my previous post because I disagreed with you! Please take a more scientific approach here and try to find out why someone with my experience should say what I did!

    Reply
  • Elysian

    There IS an audible difference with certain powercords! So be it. No further discussion.

    Reply
    • Your assertion has never been shown to be true. And that’s also a fact.

      Reply

Leave a Reply

Your email address will not be published. Required fields are marked *