12VDC versus 240VAC HiFi

[Mohsen]

After much research and advice from the wise fellows of the forum, I'm setting up a media server with Raspberry Pi + HiFi Berry.

I had assumed that a 12v dc audio system, much like a cars, with amp, 2 way component speakers and a sub woofer, would be the most efficient way to create a sound of decent quality for less power consumption. However, after doing some hypothetical maths....

• 2 Pairs of Speakers = 560 watts
• Subwoofer = 240 watts
• Amp = 640 watts
• https://www.caraudiocentre.co.uk/product_m-alpine-sxe-1750s_p-20265.htm
• https://www.caraudiocentre.co.uk/product_m-alpine-pwe-s8_p-33197.htm
• https://www.caraudiocentre.co.uk/product_m-alpine-pmx-f640_p-23894.htm

Thats a lot of consumption and a lot of voltage drop to contend with. Are the figures stated on car audio products theoretical or are they typical? Might a 240v system be more efficient in this circumstance after all?

Are there any other boaters with a HiFi / audiophile background who could offer an opinion or perhaps explain their setup?

Many thanks 

[dmr]

The speakers dont take any power from the 12v supply, and neither does the subwoofer unless its active. The 640watt is the absolute maximum power that the amp can supply to the speakers, not the power that it consumes from the 12volts. You will likely only use that 640w for a fraction of a second once in a blue moon, if ever. Most of the time you will be sending probably less than a watt or so to the speakers. What really matters is how many watts the amp is taking from the 12 volt during typical use and the manufacturers rarely quote that figure. My car radio is typically drawing less than an amp from the boat 12volts but I am aware that some car hifi types have to fit bigger alternators so I really don't know where all their power goes.

I suspect the differences between different systems are more significant that the 12v/240v decision.

Class D (or T) type amplifiers might be more efficient but I have no first hand experience of these.

Are you sure that a good car stereo would not meet your needs?

..............Dave

[MtB]

On 31/10/2017 at 23:41, dmr said:

Are you sure that a good car stereo would not meet your needs?

 

I suspect the way the OP is using the term 'hifi', he is not an audiophile looking for high fidelity sound reproduction as exemplified by Quad's slogan from the 1970s "The closest approach to the original sound". Rather, someone using the term to mean a sound system that just packs a hefty bit of punch in which case I agree, modern car radios are remarkably good when connected up to a large pair of really high quality domestic floor standing speakers. 

I have a JVC KD-D895BT driving a pair of Tannoy 611 MkII Dual Concentric floor standing loudspeakers and the sound quality is delightful given the low cost of the whole system. The 611s are an old model and deeply unfashionable in appearance so sell on ebay for shockingly small sums, and therefore represent spectacular value for genuinely hifi money.

http://www.audioreview.com/cat/speakers/floorstanding-speakers/tannoy/611mkii/prd_120655_1594crx.aspx

https://www.ebay.co.uk/itm/Tannoy-611-MKII-Stereo-Speakers/332430001288?hash=item4d665f4488:g:ZDYAAOSw41tZ46vh

[dmr]

Only possible issue is that speakers like this are most likely 8 ohm whilst almost all ordinary car stereos are happier with 4 ohm speakers so you want get the full power out of them. If they are loud enough this is not an issue.

Essential the amplifiers have to run off 12volt so the maximum power they can produce is limited by this 12 volts. $ ohms gives more amps so more power for the same voltage. The "proper" car amplifiers get round this by stepping up the 12 volts.

I do wonder how a pair of small modern bookshelf speakers plus a subwoofer would compare with your big speakers?. One thing that has advanced quite a bit over the years is getting more good quality sound out of smaller speakers.

...............Dave

[MtB]

On 01/11/2017 at 00:33, dmr said:

If they are loud enough this is not an issue

 

Tannoy dual concentrics are famous for their efficiency.

The really expensive Dual Concentrics are favoured by the extreme audiophiles who build their own 3w and 5w valve amplifiers find the volume from them more than adequate. The speakers I suggested are however infinite baffle rather than folded horns like the best Tannoys, but they have a 'passive driver' which ramps up the efficiency far above ordinary infinite baffle speakers.

[nicknorman]

... or get some decent headphones, then you won’t be a noise fascist!

[Sea Dog]

My guess would be that, for a similar quality and level of output, if there were any efficiencies to be gained by going the 240V route they would be offset by the losses in the inverter producing the 240V.  Interesting though, and I'm looking forward to the conclusion.

 

[cuthound]

36 minutes ago, nicknorman said:

... or get some decent headphones, then you won’t be a noise fascist!

Yes and pound for pound spent you get far superior sound quality from headphones than speakers.

[Mohsen]

9 hours ago, dmr said:

The speakers dont take any power from the 12v supply, and neither does the subwoofer unless its active. The 640watt is the absolute maximum power that the amp can supply to the speakers, not the power that it consumes from the 12volts. You will likely only use that 640w for a fraction of a second once in a blue moon, if ever. Most of the time you will be sending probably less than a watt or so to the speakers. What really matters is how many watts the amp is taking from the 12 volt during typical use and the manufacturers rarely quote that figure. My car radio is typically drawing less than an amp from the boat 12volts but I am aware that some car hifi types have to fit bigger alternators so I really don't know where all their power goes.

I suspect the differences between different systems are more significant that the 12v/240v decision.

Class D (or T) type amplifiers might be more efficient but I have no first hand experience of these.

Are you sure that a good car stereo would not meet your needs?

..............Dave

 

Thats useful info cheers. So if you were placing that amp say 5m from the power source and trying to work out voltage drop to size cable, would you use that figure of 640watts? e.g. if I ran 10mm2, I calculate around 10% voltage drop between battery and amp.

I am limited by a few factors, space being the obvious one on a boat and the fact that they will be playing MP3 (albeit high bit rate). I'm going for Raspberry Pi + HiFi Berry as none of the car stereo's I have found have the functionality I want.

As for the headphones argument. I have a decent pair of sennheiser 25's. However, these don't work so well when others want to enjoy the music/movie. It shouldn't be assumed (although it always is by at least a few) that when someone wants a decent sound system, they intend to crank it up and disturb everyone else.

[Dr Bob]

1 hour ago, Sea Dog said:

Interesting though, and I'm looking forward to the conclusion.

 

Yes, me too. Some good stuff above.

38 minutes ago, cuthound said:

Yes and pound for pound spent you get far superior sound quality from headphones than speakers.

...but it makes it difficult to get to the kitchen and back for another beer! .....and if I ask SWMBO, she tells me I am shouting.

[OldGoat]

'Speakers are rated in "music power" watts which - in my cynical view - bears little relation to "Watts RMS". It was and is an attempt to make speakers appear more powerful than they are.

I have no idea how you estimate the real power consumption of an installation, other tan measuring it in use.

[dmr]

1 hour ago, Mohsen said:

 

Thats useful info cheers. So if you were placing that amp say 5m from the power source and trying to work out voltage drop to size cable, would you use that figure of 640watts? e.g. if I ran 10mm2, I calculate around 10% voltage drop between battery and amp.

I am limited by a few factors, space being the obvious one on a boat and the fact that they will be playing MP3 (albeit high bit rate). I'm going for Raspberry Pi + HiFi Berry as none of the car stereo's I have found have the functionality I want.

As for the headphones argument. I have a decent pair of sennheiser 25's. However, these don't work so well when others want to enjoy the music/movie. It shouldn't be assumed (although it always is by at least a few) that when someone wants a decent sound system, they intend to crank it up and disturb everyone else.

Right, to be rude and contentious, if you are listening to MP3 you might as well as forget hifi and just use a really cheap car stereo.

Any good (mechless) car stereo will have aux input so you can plug your "media server" into that. You get the advantage of convenient  radio reception and even bluetooth if you like that sort of thing.

That 640w will only ever be used for a fraction of a second. though strictly due to amplifier ineffficienct the pull from the 12volts will be at least twice that. But, short transients  will come out of the amplifiers supply capacitors rather than down the cable. Once again we really need to know the typical current draw.

I would guess that 6mm cable would do, but obviously 10 would be better. Because the cable run is longer than a car, and because there will be transient demand it might well be worth one of those Huge capacitors that the car HiFi use.

On this subject, you will need to take great care with the cabling and the amp (or car stereo) and your "media server" must be off the same supply and close to each other. I use my laptop as my music source ("media server") with a huge hard disc full of WAV files (and some MP3) and a half good USB sound card. The laptop is on the table here but the car stereo is a few feet away but fed from a totally separate 12 cable. It sounded bad with tone of interference due to the different zero voly potentials due to the negative cable volt drops. There is actually potential for doing big damage too. My solution was a little audi transformer but that I suspect this would upset the HiFi purists (or maybe even please them as tey like valves and old technology).

I agree that headphones do have a place but they are just not the same "experience" and are not sociable, though silent discos are rather fun. Bluetoooth headphones are attractive but in my opinion bluetooth is surely the modern day work of the devil.

..............Dave

[GUMPY]

Bluetooth and MP3 have no place in the world of decent sound reproduction.

[WotEver]

1 hour ago, dmr said:

Right, to be rude and contentious, if you are listening to MP3 you might as well as forget hifi and just use a really cheap car stereo.

It's certainly not a contentious point...

[dmr]

15 minutes ago, Loddon said:

Bluetooth and MP3 have no place in the world of decent sound reproduction.

Yes, but we are fighting a loosing battle here.

One could argue that the speakers will always be the weakest link rather than the MP3, and high rate MP3 might be ok, but I reckon that speakers mostly just mess up the frequency response a bit and make some not unpleasant harmonic distortion. MP3 does bad stuff. I am sure that I sometimes hear all sorts of unpleasant "harshness" in MP3, at least at typical bitrates, and my hearing is not the best after years of abuse. If its there at lower bit rates then it must be there to a lesser extent at higher bit rates?.

My wife has one of those little Bose Bluetooth speaker things which is truly impressive but I find it wearing at  higher volumes or for longer periods.

..........Dave

[WotEver]

1 minute ago, dmr said:

I find it wearing at  higher volumes or for longer periods

And that's the big give-away of 'lesser' systems. I have an old-school system that I can (and do) listen to for hours. I also have, elsewhere, a cheap 'n cheerful Sony CD setup which becomes tiring after more than half an hour. 

6 minutes ago, dmr said:

If its there at lower bit rates then it must be there to a lesser extent at higher bit rates?.

Absolutely...

http://uk.pcmag.com/audio-reviews-and/66745/news/why-your-mp3s-sound-bad-high-resolution-audio-explained

[dmr]

We've got a fairly old but good JVC car radio (The CD bit has not worked for years, they never do on a boat) driving 4 reasonably ok car speakers. Its good enough for me except the speakers rattle with deep bass, and we do like a bit of Reggae and Dub from time to time. If ever I get miserable Dub side of the moon cheers me up.

What I would like to do this winter is find a good mechless car stereo that has a subwoofer output with selectable cross over frequencies and stick a small passive sub woofer behind the sofa. It will certainly have bluetooth so hopefully Gillie will use that rather than the Bose and I can still send my WAV files via the USB soundcard.

The only real issue is that they almost all have the aux input on a 3.5mm jack on the front panel and I would prefer the inputs, probably phone, on the back.

..............Dave

[GUMPY]

I don't care how high the bit rate is I can still hear  (sh) it when listening to MP3.

I dont listen to music on the NB as there is just not room for a decent system. On the barge I did but that system is now in the cottage with upgraded speakers. I'm still tempted by a Quad CD player to replace my modified Marantz then the whole system will be from one manufacturer 

[cuthound]

1 hour ago, WotEver said:

And that's the big give-away of 'lesser' systems. I have an old-school system that I can (and do) listen to for hours. I also have, elsewhere, a cheap 'n cheerful Sony CD setup which becomes tiring after more than half an hour. 

Absolutely...

http://uk.pcmag.com/audio-reviews-and/66745/news/why-your-mp3s-sound-bad-high-resolution-audio-explained

The link confirms my findings, although my ears are no longer what they were. 

For convenience I re-ripped all of my CD's into FLAC and back to back listening skills gains the original CD show little if any loss of sound quality. Any differences can, I think, be attributed to the A/D converters in the CD plater and streaming equipment.

The main advantage is I no longer have to look through several hundred CD's to find a particular track, I simply searth my music files for it and be listening to a Pacific track in seconds, not hours.

[MtB]

1 minute ago, Loddon said:

I don't care how high the bit rate is I can still hear  (sh) it when listening to MP3.

 

There was a programme on the wireless a couple of years ago discussing the considerable shortcomings of MP3. The illustrated the considerable amount of music information lost in the encoding by playing a CD music track with the MP3 track subtracted from it. The resulting ghostly sound was perfectly recognisable as the track, and represented they said, the missing data. 

I think people these days use the term 'hi fi' very loosely. The OP simply means a sound reproduction system. He is not interested in the highness of the 'fi' or he would be limiting his sound sources to vinyl and FM. Or possibly a Revox (or better) tape machine running at 7.5ips. Or arguably, a top flight CD player.

 

[GUMPY]

7.5ips surely you mean 15ips!

[dmr]

25 minutes ago, Mike the Boilerman said:

 

I think people these days use the term 'hi fi' very loosely. The OP simply means a sound reproduction system. He is not interested in the highness of the 'fi' or he would be limiting his sound sources to vinyl and FM. Or possibly a Revox (or better) tape machine running at 7.5ips. Or arguably, a top flight CD player.

 

Hiss crackle pop    hiss crackle pop   hiss crackle pop   hiss crackle pop   hiss crackle-pop + end of side distortion. 

and it wears out a bit more everytime you listen to it.

...........Dave

[Jess--]

26 minutes ago, dmr said:

We've got a fairly old but good JVC car radio (The CD bit has not worked for years, they never do on a boat) driving 4 reasonably ok car speakers. Its good enough for me except the speakers rattle with deep bass, and we do like a bit of Reggae and Dub from time to time. If ever I get miserable Dub side of the moon cheers me up.

What I would like to do this winter is find a good mechless car stereo that has a subwoofer output with selectable cross over frequencies and stick a small passive sub woofer behind the sofa. It will certainly have bluetooth so hopefully Gillie will use that rather than the Bose and I can still send my WAV files via the USB soundcard.

The only real issue is that they almost all have the aux input on a 3.5mm jack on the front panel and I would prefer the inputs, probably phone, on the back.

..............Dave

have a look at the tpa3116 amps on ebay (search for tpa3116 2.1 bluetooth), they have all the inputs / outputs on the back + bluetooth, are small, dc powered (ok on 12v or 24v) and have plenty of punch, 2 x 50w + 1 x 100w (all RMS)

downsides are that it is not car stereo sized (it's a hell of a lot smaller) and the crossover freq is not easily adjustable

I have 3 of them in use (1 with bluetooth and 2 without) and have had no issues despite them driving fairly meaty subs

[WhiteSuit]

Interesting topic, I love my music and listen at home with NAD equipment driving B&W speakers preferably from a vinyl source. This provides what I consider to be a realistic hi fi sound. My wife has no musical taste so I also have a set of B&W headphones which shields me from mind numbing tv!  When you have a good setup you don't need to be unsociable with volume to appreciate the sound. 

I was advised by my local car audio shop not to use domestic speakers with car CD player as the ohm difference requirements would destroy the speakers. Their advice was Alpine CD player linked to Focal speakers and a sub. I was impressed and upgraded basic component speakers initially and they are reasonably impressive for their small size. I don't think I can justify the £250 price tag of the matching sub and find a place to fit it for the improvement it would give. 

My question is how to wire in a socket to plug in my decent headphones as this would give me the best sound for pound as I am the only person on board who requires this. Car sets don't have a headphone output. Could I simply wire in the second speaker output from the set to a headphone socket? The only details I can find are that they have a resistance of 26 ohms. Any answers please?

[Sea Dog]

AM radio anyone?