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Music Centre playing up

Discussion in 'Audio Visual' started by alwaysworried, 19 Oct 2015.

  1. gman76

    gman76

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    Hi AW,

    The lens in CD players is quite delicately suspended in order for the radial & focus coils to continually move it into the correct position while playing a disc. Unless the classic lens cleaning disc has changed recently, they have a ring of small barbs/bristles that physically scrape across the lens. Not the way I'd wish to treat it.

    I'm not sure of your budget, but I found this while searching for a system for my MIL recently (didn't buy it in the end), it has a range of old & newer features, including CD, CD-R & CD-RW playback.

    https://www.richersounds.com/teac-system-inc-speakers.html
     
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  2. alwaysworried

    alwaysworried

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    Thanks, very much, gman, for your suggestion about the CD player above. However, it features a deck for vinyl records, which, for me, would be superfluous, and create needless expense. After looking around, I found this (Panasonic SC-PM250BEBS DAB Micro Hi-Fi System, at: https://www.amazon.co.uk/Panasonic-SC-PM250BEBS-Micro-Hi-Fi-System-Black-Silver/dp/B00TTYOG2Q), which seems to be what I need (it seems to be good enough, as regards quality of sound, at least). However, ignorance on my part makes me afraid to order it. I sent a few questions to the merchants that are selling in via amazon, but they could not offer any information. except to send the user manual pdf, which (except for two snippets of information), leaves me in the dark as much as I was without it. The information I gained from the manual is that its speakers are of 6 ohms impedance. Now, the speakers that come with this set could not be conveniently used, because the set would need to be put on top of a tall cabinet (a CD-holding cabinet) that does not have much area to put anything on the top. There would not be enough room for the speakers. Besides, on the walls of our lounge, there are fairly large speakers already fixed in the best positions for sound entry-points, and I should very much prefer to use those, if possible. However, I don’t know whether these existing speakers would be compatible with the player in question. The reason for my uncertainty (I assure you, I’m very ignorant in matters like this) is that there is a sticker on the rear of our existing speakers, which states that they are of 15 ohms impedance. Now, I don’t know whether this means that the player I should like to buy would be incompatible with these speakers, or not. I mean, seeing that the speakers that are supplied with the player are only 6 ohms, would this imply that 15-ohm speakers would be incompatible with the player, or would they transmit sound, regardless of this difference? I’m out of my depth!
    Also, though the set that I mention, above, will play CDs, of course, in the user manual, under the heading of Media Playback, it says this:

    “The following marks indicate the availability of the feature.

    CD-R/RW in CD-DA format or with MP3 files.”

    Now, I examined the file format of my home-burned CDs (burned using Roxio Toast, on my Mac), and saw that they are .aiff files. Would these play in the player I am considering?

    I very much hope that, with your greater knowledge of technology, you will be able to tell me that the player specified above will be OK in respect of using our old speakers, also the matter of playing home-burned CDs. Or that you know enough to tell me that it would not suit my needs.
    With thanks in anticipation of more advice/comment,
    A.W.
     
  3. gman76

    gman76

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    Hi AW,

    I would think that your speakers should be fine as they present an easier "load" on the amplifier, you just wouldn't be able to reach the full quoted output power as this is measured at 6 ohms. Only a problem if you like to push the volume to its limits. (Hopefully @Lucid will come along and correct me if there may be output filter implications on class D)?

    As for your burnt CDs, if you have burnt them as audio discs rather than data and they played on the Daewoo, they will play in the Panasonic. Your Mac will just show the file format as AIFF (Windows may show WAV) as they are uncompressed audio.
     
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  4. alwaysworried

    alwaysworried

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    Yes, they were burned as audio discs. What you say is very reassuring, gman. In view of what you say, I shall go for the Panasonic SC-PM250BEBS DAB Micro. It would be marvellous to be able to play our music once again! I noticed, when cleaning the lens manually, on the Daewoo, that the inside of the case (it was necessary to take the turntable out) was covered with grey dust, which I cleaned off, of course. However, in view of your not favouring lens-cleaning discs, would not the lens also quickly get covered with that dust? I should not like to have to take the turntable off every few weeks, to clean the lens manually!
    Thanks indeed for your speedy response.
    A.W.
     
  5. gman76

    gman76

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    The majority of loose dust will probably be removed by the air flow from the rotating disc above, it's a film layer of grot that builds up, similar to the inside of car windows that needs to be removed.

    This should only be necessary after a few years (less if you are a smoker, the unit is situated in a kitchen or live in an area with higher pollution). I would only suggest cleaning it when you encounter reading issues across multiple discs.

    As Lucid said, the reflectivity of burnt discs is less than that of a pre-recorded disc, so your milage may vary & you may need to clean the lens more frequently.
     
  6. Lucid

    Lucid

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    @gman76 is correct when he says that it's okay to run higher-impedance speakers with an amp rated for something lower. In the case of a 15 Ohm speaker with an amp rated for 6 Ohms, the result will sound like you're working with about 40% of the amp's power output, so yes, the speakers will sound quieter, or you'll have to run the volume harder to compensate.

    There is a caveat though. There has to be enough power coming from the amplifier itself so that the system can afford to lose 60% of it. This is where I think this little Panasonic (and many similar systems) will come unstuck.

    A quick glance at the specs shows me two sets of figures that confirm my suspicions. The first is how they measured the power output: 10W (1kHz, 6ohms, 10% THD). The second is the systems total power consumption in 'normal' operation: 14W

    The power output figure doesn't tell me everything about how they got to 10W per channel. For example, were they driving just one channel or both? I suspect it was just single channel.

    Okay, here we go...

    1) The reason for a 6 Ohm rating rather than 8 Ohms is because it makes the power output look better. Getting 10W in to 6 Ohms means that the amp is generating roughly 7.75 Volts. The same voltage in to an 8 Ohm load gives me 7.5W. The speaker is actually an easier load to drive, but now it seems on paper that we lost 25% of the power. Marketing men hate that. They want the biggest numbers they can get, by fair means or foul.

    If I do the power equation for a 15 Ohm load then the wattage drops to 4W.


    2) The 1kHz signal is a test tone. It's where the amp is operating at higher efficiency, but it doesn't accurately represent what happens when the system has to play real music. I have seen amp paper power figures 'boosted' by quite a bit as much as 17% using this trick. Lets be conservative then and say that we only need to knock off 10% from the power figure to neutralise this cheat.

    3) 10% THD is the amp working very hard, a bit like running a car's engine flat out and in to the red zone on the revs. The car doesn't travel much faster, but sounds far rougher. At 10% THD you'll start to hear the amp struggling. The tone will take on a sharper, raspier edge.

    Measuring the power at 10% THD can inflate the figure by as much as 20% with some amps. Again though, we'll be generous and say we have only to reduce by 10% to get a more sensible number.

    4) One channel driven: Leaving one channel idle means that some of the unused power can be siphoned off to the channel being measured. It's another 10% reduction to neutralise the effect.

    5) Did they measure the power with the tone playing continuously, or was it just for a fraction of a second?


    If I take the 4W for a 15 Ohm speaker, then knock off each of the 10% factors in turn, then the final result is 2.6W per channel. It's true that we don't need a lot of watts to start making some noise with an audio system, but you do need some headroom to handle the louder passages without the amp crashing in to its own red line and distorting.



    The other thing I look at is the audio system's power consumption. Any bit of audio gear is simply taking some power from the AC mains socket and converting it to power suitable to drive a speaker. A Watt is a Watt whether it's coming from the mains or going to a speaker. Since we haven't yet invented an amplifier that breaks the Laws of Physics by making more Watts than it sucks from the mains, then whatever the power consumption is, minus some losses for running the electronics and for heat losses, that's the available power to the speakers.

    This Panasonic running in 'normal' use consumes 14W. Its supposed 10W per channel is more like 7.5W/ch at close to full volume, so it might be reasonable to say that the amp running at half power is kicking out around 7-8 Watts in total. Some of the power from the mains goes to run the features and display of the sound system, so lets say 4W. Then there's the amplifier section itself. 'Digital' amps (class D switching amps) can be up to 90% efficient, but those ones are expensive. A typical budget switch mode amp runs at 70% efficiency, so if we take what's left of the 14W from the mains (10W), then knock it down to 70%, we get 7W. That gives us 3.5W per channel in to 6 Ohms.
     
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  7. alwaysworried

    alwaysworried

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    Well, no one smokes in our house, gman, so there is not much risk of it fouling up. I didn't know that there is any kind of rotating disc that would tend to clean the lens.


    Thanks for the information (gman) and the warning (Lucid). Whew, Lucid, I could never understand, in a hundred years, all the stuff that you spouted. However, I could understand the first bit (quoted), so I take notice of that.

    I need to be absolutely sure that what I eventually buy will work with regard the our existing speakers, also the home-burned CDs. So, in view of your reservations, I have decided not to go for the Panasonic, after all. The only one that seems to come near to being a safe bet, as regards those two factors, is this:

    Sony CMT-SBT100B All-in-one Audio System with Wireless Streaming, 50W. I downloaded the user manual, and have copied a bit of material from it, and will paste it in. It says:

    CD-DA/MP3 player section

    System: Compact disc and digital audio system Laser Diode Properties

    Emission Duration: Continuous
    Laser Output*: Less than 44.6 μW
    *This output is the value measurement at a distance of 200mm from the objective lens surface on the Optical Pick-up Block with 7mm aperture.

    Frequency response: 50 Hz – 20 kHz Signal-to-noise ratio: More than 90 dB Dynamic range: More than 90 dB

    Inputs/Outputs

    AUDIO IN (external input) jack:
    Stereo mini jack, sensitivity 700 mV, impedance 47 kilohms

     (headphone) jack:
    Stereo mini jack, 8 ohms or more

    I thought that to paste it in would make it more easy for you to express an opinion. However, the link to download the user manual is here:
    https://www.manualslib.com/download/906963/Sony-Cmt-Sbt100.html

    If it's not too much trouble for you, I should be very grateful if each of you would please express your opinion about this machine. If you, gman and Lucid, are able to OK it (I mean, as far as my concerns — as stated — are concerned), i would order it. What I am asking/hoping for is a kindness similar to someone finding a seat, on a bus, for a blind man. You can't imagine what a big thing it is for someone as green as me, to be ordering expensive stuff like this!
    With grateful thanks in anticipation,
    A.W. ("the worrit", as they say up here in the North of England)
     
  8. Lucid

    Lucid

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    The Sony is double the price of the Panasonic, and it is an improvement in power too, but I wouldn't exactly call it home and dry.

    As a rough estimate you have around 5 to 6W per channel from it. Still not great. What also concerns me about the Sony is the frequency response.

    It appears that if you play CDs then the lowest frequency they'll deliver is 50Hz. That sucks! Sure, maybe it matches the performance limits of the supplied Sony speakers, but anyone such as you who plans to use something better that can probably gets a nice rich tone is going to find themselves disappointed that the sound is artificially truncated. Play a tape or LP on your current system. Turn the bass control all the way down. Ta-dah! Limited bass. It's a cheap trick to save putting some half-decent amplification in the box. It also explains why the power figures don't add up. Bass requires a lot more wattage than midrange and treble. Chopping off the bottom end of the amplifier frequency range is a cheat to save money. Is that what you want from your audio system?

    You said you didn't want to buy something used, and I totally understand, but if you go for the Sony, or the Panasonic, then you're going to be buying a complete system with a pair of speakers that are redundant for you. I'm going to be brutally honest here, the speakers of such systems aren't great, so if you plan to use them somewhere else or sell them on then be prepared to be underwhelmed.

    When you started this thread almost four years ago I mentioned the Denon D-M39 DAB. This is a micro system of similar footprint size to the two you've been looking at, but there are some crucial differences too. The model has been superseded a couple of times. The current version is the D-M41 DAB.

    Firstly, it's available with or without speakers. The ex-speaker guise can be bought for around £220. Two things from this: 1) it's not far off the price of the £195 price of the Sony, and 2) you're not wasting money on speakers that aren't needed, so all the money is going in to the piece you want.

    Next, there's more power from the amp. It's rated at 2x 30W in to 6 Ohms. That netts down to around 10W per channel. Now you have something that's three times the power of the Panasonic for the same price as the less powerful Sony. The Denon is an award winner too. See LINK

    My F-in-L has had his Denon D-M39DAB for a little over four years. He plays music on it every week. It hasn't missed a beat.

    I had a think about used alternatives that might have more power. There was the ARCAM Solo Mini which netts to the same 10W in to 15 Ohm. The TEAC Reference 300 and Ref' 500 systems have more power, but finding a good used one isn't a job for a novice. All these were a lot more money than the Denon when they were available new. I'm talking £500 to £800. That makes the Denon very good value, and IMO a very good choice for you.

    If this or any other reply was helpful to you, then please do the decent thing and click the T-H-A-N-K-S button. It appears when you hover the mouse pointer near the Quote Multi-quote buttons. This is the proper way to show your thanks for the time and help someone gave you.
     
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  9. alwaysworried

    alwaysworried

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    Thanks, as usual, Lucid, for spelling it out so finely. (By the way, in being engrossed in reading and replying, sometimes, I forget to click the Thanks button. I have now corrected that omission.) What you say is good advice, I am sure, but, since you have given a kind of thumbs-down to the Panasonic and the Sony machines (your advice is what I asked for, after all), I looked at the Denon with the link provided. However, it is out of this pensioner's price range at the moment. I shall need to confer with my better half about that, and perhaps, at a later date, we may buy the Denon.

    I suppose that this now concludes our long-drawn out conversation. You have saved me from making an expensive mistake, at least. I really do appreciate the time and trouble that you and gman have taken to comment on my enquiries, so I offer my grateful thanks to you both (and I click the Thanks button).

    Best wishes to you and gman, A.W.
     
  10. Lucid

    Lucid

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    Price was one of the issues I was very careful to address, so I'm rather surprised that you infer that the £189+delivery Sony with its redundant speakers is at an acceptable price, and yet the Denon in silver at £199.90+del from Peter Tyson is considered "out of this pensioner's price range". The logic in your decision escapes me, particularly when the Denon addresses a key area where the Sony is weak. Care to explain the thinking?
     
    Last edited: 10 Aug 2019
  11. alwaysworried

    alwaysworried

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    I can understand your puzzlement, Lucid. The fact is, I must have looked at the wrong item, as I thought that what you were suggesting was three hundred and odd pounds. I shall take another look at it.
    A.W.

    I did take another look at it, Lucid, and I found a rather off-putting review from a user. I paste it in: Bought this but had to exchange it as some of my original cd’s (not copies) would not play - it just displayed “unsupported”. Richer Sounds Guildford gave me a new replacement unit but that still sometimes refuses to play cd’s that I have bought. It also doesn’t play cd-r copies at all. Very annoying and has spoilt what is otherwise a great sounding unit. END OF PASTE-IN

    Most of my CDs are CD-Rs.
    Regards,
    A.W.
     
    Last edited: 10 Aug 2019
  12. Lucid

    Lucid

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    You ought to take a look at the reviews of the Panasonic and Sony systems you were considering. Here are just a few excerpts. Each line is from a different user's review:

    Panasonic

    "We ordered two different models unfortunately the first one didn't work. The second CD player work fo 10 minutes"

    "Sound quality is crap"

    "Don't waste your money. Rubbish, even for a midi"

    "Very cheap and nasty cds either jumped or was running fast"

    "I found I couldn't skip more than one or two tracks - if I did it stopped playing completely and I either had to eject and reinsert the CD, or turn the unit off and on again"

    "...attempt to play a CDR. It didn't work and I thought perhaps that it may have been due to it being a CDR so tried a further two factory recorded discs. Responses NO PLAY and NO DISC"


    Sony

    "Bought this to play my CD,s problem being it will not play any of them not even sony label bands, total rubbish"

    "Awful product! Cheap, lightweight feel to it. Sound quality below average."

    "...had 2 CDs freeze while playing, these CDs have no scratches whatsoever and they play on all other CD players"

    "took ages to load and read CD and the CD tray action was noisy and clunky"

    "Played one track from a CD, let out a high pitched noise and stopped playing. Will not play or eject the CD"

    "It's a cd player that does not play cd's! Avoid!"

    "...the sound quality is awful. ... There is no presence or clarity whatsoever, just annoying vibration."


    "now failing to play (CDs) at all - occasionally showing the total track length and track count, but usually just displaying 'no disc'."


    End-user reviews tend to be something of a mixed bag. Positive and negative reviews need to be taken with a pinch of salt. I understand you reading the reviews and expressing a bit of caution. However, I also think you need to take a look at the bigger picture.

    No matter what piece of consumer electronics one buys, there will always be product failures. The industry average is 2-4% depending on the type of tech' and - to some degree - how close it is to the bottom or the top of the price range of its peer group. If you're looking for perfection both out of the box and for any length of time then you'd better give up with consumer electronics and start buying flawless diamonds.


    You're here because your existing stereo is broken. Doing a repair probably isn't cost-effective, so you're now looking at a replacement, but you have certain restrictions such as size, function, cost, being new, and the technical requirement of driving a set of high Ohm (large-ish?) speakers.

    The first product you listed won't meet your needs. We saved you from a lot of disappointment and wasted time with that one. Need I remind you also that you were ready to push the buy button on it, and not once did you question its poor reviews? For your next choice you doubled the budget. That was sensible. But it has some (IMO) some serious technical shortcomings. Yet again though, you never made a peep about the reviews.

    I have shown you a product that appears to fit all your specific requirements, and is near-as-damn-it bang on budget, and that can drive those speakers better than anything else under £300. Now suddenly you're picking holes and coming up with excuses. In the psychology of sales we call that behaviour unreasonable objections. It's a delaying tactic. It shows that the customer's needs have been met but they're fighting saying yes because it means admitting that their quest is at an end is scarier to them than pretending that no solution is good enough.

    The Denon D-M41DAB isn't flawless. No product is, and certainly no product is for just a couple of hundred quid. However, it does have better reviews than the Sony.

    What I would suggest is you arrange to demo the Denon at a Richer Sounds store. Take along some of your home-recorded CD-Rs and try them in the system.
     
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  13. alwaysworried

    alwaysworried

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    Lucid, first of all, I was mistaken about the price (I failed to acknowledge this fact, in my last post). The Denon is just about within our means. If I can find a Richer Sounds store within striking distance of my home, I will do as you suggest. It's the home-burned CDs that is my main concern, now, seeing that, from what you tell me, the existing speakers will not cause problems as with the other models I considered. I live near to central Manchester, and the city shopping centre is about the furthest I am able to go, not having my own transport, and not being physically very mobile. I shall now look for one of the Richer Sounds stores. If there is one in central Manchester, I should be able to put every last concern to rest.

    You certainly analyse things very thoroughly! Thanks, once again, for your comments.
    Regards, A.W.

    Lucid. Hey, I did find a Richer Sounds store within striking distance of my home (in Manchester). After a telephone conversation with a store staff-member, yesterday, today, I took a tram into Manchester, and the staff-member demonstrated the Denon D-M41DAB to my total satisfaction, playing a home-burned CD of mine, also a pre-recorded one of mine. I bought the appliance immediately, and it is now installed in our sitting-room. It was a complete surprise to me to find that there still are stores that have the expertise/knowledge of their wares so as to be able to talk about them as this staff member did! Also, actually to demonstrate the equipment! I was under the impression that there were only the big stores, such as Curry's etc., who don't seem to have the time (or even much knowledge) of their goods to explain things to a customer before he buys. Even an enquiry by email, of a vendor of hifi goods, failed to obtain answers to my questions. They said they did not know and could not answer (being simply merchants, without much interest in the goods they sell, as long as they sell them).

    Well that ends what I found to be a big problem, and I have you (and others) to thank for being patient enough to explain things to others less knowledgeable. Believe me, I am very grateful!
     
    Last edited: 12 Aug 2019
  14. Colin Brenton

    Colin Brenton

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    Nice work Lucid, and gman76, thanks for sharing your knowledge; I've learnt a good bit as well from this thread :)
     
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  15. Lucid

    Lucid

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    Hello A.W.
    I hadn't realised you updated your story. Edited posts don't flag up the same way as new posts. Anyway, thanks for the update.

    Your comments about Currys and similar big electrical stores really don't surprise me. I don't want to knock them too hard - hell, there aren't that many retailers left - as I know from delivering training to store staff in Currys branches up and down the country that there are some folk who are passionate about what they do. Sadly though, the culture in the business is more about targets and promotions rather than consultative selling and finding customer needs.

    When I started my own journey buying Hi-Fi back in the 80s, Richers were very much in the pile-'em-high-sell-'em-cheap end of the market. A lot has changed in four decades.

    Many of the specialist retailers have gone, and quite a few of not-so-specialist ones too! Julien Richer still specialises in scooping up end-of-line ranges and offering them out at big discounts. However, brands that wouldn't have touched Richers with a barge pole ten years ago are now finding it hard to maintain sales volumes through the dwindling numbers of specialist dealers. Others leverage Richers advertising by giving the company access to their lower-tier products. However it is done, Richers are picking up their game, so that's a good thing from customers' perspective.

    What I would say is that if you thought Richers were knowledgable, then really you've only dipped your toe in the shallow end.

    The North West of England is still well served by specialist dealers, some of whom have been around a long time. For customers who are spending £500 and above, there is a whole other level of performance and knowledge to tap. For example, you were surprised that you could get a demo. I'll bet that when you did, your demo (if it wasn't on the shop floor) was in a dem room piled high with electronics and speakers. That goes against the grain for the real specialist retailers. Done properly, a dem would never have more than one pair of speakers in the room, even if those other speakers were disconnected. That second set will resonate in sympathy with the sound being played, and that would mar the sound of the speakers being auditioned.

    If you ever had five numbers come up on the lottery, or got a nice little £1500 windfall, then a visit to The Audio Works in Cheadle (nr Stockport) or Doug Brady Hi-Fi in Warrington would open your eyes and ears to a whole new world of possibilities. There are other retailers too, but they're a bit further afield.

    I am glad we've brought this to a happy conclusion. I hope you mentioned the outstanding level of support you received here in this forum?

    All the best

    Chris
    Lucid AV
     
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