More 'Audiophile' bullsh*t

[Le TVR]

Chassis is DIY too.
Offcuts of 2 and 4mm alu sheet and big box of heatsink units that I found at a scrap metal dealer!

[TonyRPH]

Le TVR said:

Chassis is DIY too.
Offcuts of 2 and 4mm alu sheet and big box of heatsink units that I found at a scrap metal dealer!

You did a good job! It looks quite professional.

Many moons ago I hand fabricated a chassis using aluminium angle and some plain panels, with some heatsinks I bought.

I don't really have the patience to scratch build chassis any more though!

I used to etch my own boards too - but find that to be too much of a chore now - and it's so cheap to buy from China these days, there's not much point really.

[Globs]

The Maplin DIY stuff looks most interesting, I'm trying to find pictures of my Maplin MOSFET amps. I still have the amps so I can always take new pictures if required .

[Driller]

Le TVR said:

I have a colleagues Azur phono amp here for de-bugging. He's changed the op-amps for AD827 types that he bought off ebay. God knows what they really are, probably TL071s.

Sorry but reminded me of this:

http://m.youtube.com/#/watch?v=2un9rO2ZF4g&des...

[BliarOut]

Driller said:

Le TVR said:

I have a colleagues Azur phono amp here for de-bugging. He's changed the op-amps for AD827 types that he bought off ebay. God knows what they really are, probably TL071s.

Sorry but reminded me of this:

http://m.youtube.com/#/watch?v=2un9rO2ZF4g&des...

I was expecting the 'bag on the head' sketch

[TonyRPH]

So, I was browsing Ebay today and I felt obliged to share this magnificent product.

Do vinyl LPs contain enough (any??) metal particles to warrant demagnetisation?

And I thought the substrate on CDs was aluminium, a non ferrous metal, and hence cannot contain a magnetic field?

All yours for £176 + postage!!!

Advert said:

Magnetically Optimizes CDs/DVDs/LPs

Magnetic fields and static electricity can greatly affect audio and video playback equipment and source material. The Talisman temporarily dissipates magnetic fields and static electricity allowing the phono cartridge or laser reader to transmit a purer, more accurate signal.

Use the Talisman to treat LPs, CDs, SACDs and DVDs. Distortion will be lowered and the sound will be more realistic. The soundstage will open up with improved depth and transparency. You will get more information without glare or harshness. Dynamics will improve and the harmonics will sound more natural. With video, you will get improved colors, focus and depth of image. The Talisman requires no batteries or power cords and never needs recharging.

[jmorgan]

If memory serves the little metal disc in the old leccy meters was an alloy or aluminium but was that disc on a shaft that was moved or was it moved by the electricity induced?

But how is something small like that going to deal with something with a lot more energy in orders of many magnitudes?

[Mr Whippy]

http://en.wikipedia.org/wiki/Cyclic_redundancy_che...

Not sure if all players will use them, but I'm fairly certain anything PC based does otherwise a CD drive on a PC would be absolutely useless for anything.

And I'm sure those who manufacture the laser readers and digital streamers will implement a crc system.

I'd worry more about the DAC as that is when things start to get 'wooly'

Dave

[BliarOut]

TonyRPH said:

So, I was browsing Ebay today and I felt obliged to share this magnificent product.

Do vinyl LPs contain enough (any??) metal particles to warrant demagnetisation?

And I thought the substrate on CDs was aluminium, a non ferrous metal, and hence cannot contain a magnetic field?

All yours for £176 + postage!!!

Advert said:

Magnetically Optimizes CDs/DVDs/LPs

Magnetic fields and static electricity can greatly affect audio and video playback equipment and source material. The Talisman temporarily dissipates magnetic fields and static electricity allowing the phono cartridge or laser reader to transmit a purer, more accurate signal.

Use the Talisman to treat LPs, CDs, SACDs and DVDs. Distortion will be lowered and the sound will be more realistic. The soundstage will open up with improved depth and transparency. You will get more information without glare or harshness. Dynamics will improve and the harmonics will sound more natural. With video, you will get improved colors, focus and depth of image. The Talisman requires no batteries or power cords and never needs recharging.

And I'll bet there's someone daft enough to use it on LPs

[qube_TA]

If it's anti-static device then it'll stop your LP's fluffing up as quickly.

[TonyRPH]

qube_TA said:

If it's anti-static device then it'll stop your LP's fluffing up as quickly.

Yes, but the advert claims "Magnetically Optimizes CDs/DVDs/LPs"...

[PhilboSE]

Mr Whippy said:

http://en.wikipedia.org/wiki/Cyclic_redundancy_che...

Not sure if all players will use them, but I'm fairly certain anything PC based does otherwise a CD drive on a PC would be absolutely useless for anything.

And I'm sure those who manufacture the laser readers and digital streamers will implement a crc system.

I'd worry more about the DAC as that is when things start to get 'wooly'

Dave

There's a difference between the standards for laying down CD audio data and other data. The Red Book defines CDDA for audio which has does have parity bits to support error detection. It may also support error correction, I don't know how much redundancy there is.

This standard wasn't deemed good enough for the persistence of computer data, so the Yellow Book was defined for this purpose with far greater (like 3 orders of magnitude) better error detection and correction.

There's loads of other standards and formats for now-defunct requirements such as Photo-CD, CDi, and all the enhanced audio/video formats for CD.

However, I'd still rate a modern transport to pick up the stored CDDA data on disc with no errors (assuming no scratches etc.). This does mean that it would be possible to get the data off the disc and into the DAC with no errors. And the DAC, knowing the sample frequency, can then do it's work on the digital sample stored in RAM, without worrying about how it got there. Which means you *could* eliminate fancy (=expensive) CD transport systems, posh USB cables, anti-jitter systems and the like.

I don't know whether anyone has such a system, but if you rip the CDDA data and then play it back via a NAS and a DAC, then you'd effectively have the same result. The rips could be done with a £10 transport on your PC and then you would have a system that should give bit-perfect, jitter-free data to the DAC every time.

[budgie smuggler]

PhilboSE said:

The rips could be done with a £10 transport on your PC and then you would have a system that should give bit-perfect, jitter-free data to the DAC every time.

You can also use accuraterip to verify the checksum of your ripped track against other people's rips to ensure that there are no errors.

http://www.accuraterip.com/

Edited by budgie smuggler on Wednesday 1st May 14:57

[BliarOut]

qube_TA said:

If it's anti-static device then it'll stop your LP's fluffing up as quickly.

I've got an anti static brush thingumy somewhere, cost about 79p

[qube_TA]

BliarOut said:

I've got an anti static brush thingumy somewhere, cost about 79p

Would scratch the LP's

[Mr Whippy]

PhilboSE said:

Mr Whippy said:

http://en.wikipedia.org/wiki/Cyclic_redundancy_che...

Not sure if all players will use them, but I'm fairly certain anything PC based does otherwise a CD drive on a PC would be absolutely useless for anything.

And I'm sure those who manufacture the laser readers and digital streamers will implement a crc system.

I'd worry more about the DAC as that is when things start to get 'wooly'

Dave

There's a difference between the standards for laying down CD audio data and other data. The Red Book defines CDDA for audio which has does have parity bits to support error detection. It may also support error correction, I don't know how much redundancy there is.

This standard wasn't deemed good enough for the persistence of computer data, so the Yellow Book was defined for this purpose with far greater (like 3 orders of magnitude) better error detection and correction.

There's loads of other standards and formats for now-defunct requirements such as Photo-CD, CDi, and all the enhanced audio/video formats for CD.

However, I'd still rate a modern transport to pick up the stored CDDA data on disc with no errors (assuming no scratches etc.). This does mean that it would be possible to get the data off the disc and into the DAC with no errors. And the DAC, knowing the sample frequency, can then do it's work on the digital sample stored in RAM, without worrying about how it got there. Which means you *could* eliminate fancy (=expensive) CD transport systems, posh USB cables, anti-jitter systems and the like.

I don't know whether anyone has such a system, but if you rip the CDDA data and then play it back via a NAS and a DAC, then you'd effectively have the same result. The rips could be done with a £10 transport on your PC and then you would have a system that should give bit-perfect, jitter-free data to the DAC every time.

Cheers for the clarification!

I'm sure a bunch of pages back someone linked to a person who had done some CD read-outs and they then checked what the DAC had received and in most cases it was identical, and that was from a range of average commercial readers iirc.

In any case, yes, getting them on a computer and then DAC'ing from there would make more sense for anyone who was worried THAT much.


But then again, if a CD is 16bit, then surely there must be a crc per 16 bit value, otherwise if the first bit were mis-read it could cause some rather odd looking waveforms hehe!


Hmm

Dave

[PhilboSE]

Mr Whippy said:

But then again, if a CD is 16bit, then surely there must be a crc per 16 bit value, otherwise if the first bit were mis-read it could cause some rather odd looking waveforms hehe!

Before being written to the disc, the LPCM audio data is divided into 12-sample frames (six left and right samples, alternating) and subjected to CIRC encoding, which segments and rearranges the data and expands it with "parity" bits in a way that allows occasional read errors to be detected and corrected. 8 bits of subcode data are added to each frame. The resulting 291-bit frame data is EFM-modulated, where each 8-bit word is replaced with a corresponding 14-bit word designed to reduce the number of transitions between 0 and 1, thus reducing the density of physical pits on the disc and providing an additional degree of error tolerance. 3 "merging" bits are added before each 14-bit word for disambiguation and synchronization. A 24-bit word is added to the beginning of each frame to assist with synchronization, so the reading device can locate frames easily. The EFM, merging bits, and sync words thus expand each frame from 291 to 588 bits of "channel data". The frames of channel data are written to disc physically in the form of pits and lands, with each pit or land representing a series of zeroes, and with the transition points—the edge of each pit—representing 1.

Shamelessly "ripped" from http://en.wikipedia.org/wiki/Compact_Disc_Digital_...

[jmorgan]

qube_TA said:

BliarOut said:

I've got an anti static brush thingumy somewhere, cost about 79p

Would scratch the LP's

Still use mine. LP's are fine.

[qube_TA]

I think that given that a decent turntable these days is going to be £four figures then you're unlikely to buy the cheapest solution possible to keep the discs clean.

Granted the item in question is a little questionable but keeping your LPs clean and static free will improve the sound quality a lot without harming them.

[jmorgan]

Mine was thrown in as a freebie when buying the turntable at the time. It was a cheap turntable so says a lot for the brush but the brush shifts the dust and fluff before you drop the needle.