John Curl's Blowtorch preamplifier part II

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The Real Steve Eddy,
You are correct that if the artist doesn't make sure that a recording is done well then all bets are off. But that is exactly Neil Young's gripe that the sound of his music is not what he hears in the studio and that is what he wants people to hear. I can't say anything about the implementation of the Pono player, that is to be seen.

Richard I guess I will have to pay more attention to the formats used to record the music and also the digital side of things. I just want to get the speakers right so whatever you have that is high quality can be heard.
 
Strangely (or not) ........
My MP3 player displays bitrate
and it jumps all around ?

Because ... one option when encoding into MP3 is to use Variable bit rate - you use more bits when things get busy, in the signal, and ease off during the simple bits. Video compression uses this technique always, except for low quality transmissions.

To add to Richard's points, the 'offness' in MP3 can be largely due to the on the fly processing in decoding the signal - take the time to create a full resolution, uncompressed version of an MP3, offline, and play that - you might be surprised ... ;)
 
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The large memory is a real draw, and makes it more practical to use lossless formats. But, I've got a Sansa Clip (had a Fuze until it was stolen), which has a micro-SD slot, and which plays FLAC, MP3, Ogg, WAV, etc. Combined with a DIY O2 portable headphone amp it drives my AKG's just fine, and blows the doors off any iPod. The Clip has consistently been rated one of the best sounding PMP's (see anythingbutipod.com). Do we really think that a $400 player will change the market more than a $69 player that plays lossless formats and outperforms the competition?

PS: I'll consider a Pono when RockBox has been ported to it!

Ditto! I've got a Sansa Clip + and was able to find a sale on 32Gb micro-SDs.

Cheap and cheerful. :cool:

On-board memory doesn't make much sense because in 8 months you'll be able to buy something twice as big for half as much ... unless it's a sound quality thing ...

Rockbox (free replacement firmware Rockbox - Free Music Player Firmware) is fun too! ;)
 
You are correct that if the artist doesn't make sure that a recording is done well then all bets are off. But that is exactly Neil Young's gripe that the sound of his music is not what he hears in the studio and that is what he wants people to hear.

Does he have artistic control over how its mastered once he's finished recording? That would be a good place for him to start. But then is he saying what's heard on people's iPods doesn't sound at all like what he heard in the studio? If so that has nothing at all to do with having more bits than 16 and sample rates higher than 44k1. However there's no marketing initiative when that's acknowledged other than ditching S-D DACs and crappy analog stages - certainly no more revenue to be gleaned from music downloads.
 
Why don't Hi-Fi mags measure cartridges or TT's anymore, why does a 5k cartridge sounds better than a 500.00 one , or does it ...

yep :drink:

With vinyl playback, the easily measurable errors are so large, and the differences that are heard are so relatively small, that it's embarrassing. That doesn't mean the differences aren't (necessarily) real and audible, however.

One thing I just came across again was the huge effect of off centering. You can easily get 20 times more wow from off centering than good turntables are capable of, from a *good* record. By eye, and taking some time to do it, you can't correct centering better than 0.1% wrms it has been claimed (so there would be great measurable and likely audible benefit of auto-center-correcting turntables using lasers). Of course it's centered near 0.5 Hz where we hardly hear it, especially those who listen to vinyl a lot. While other tiny measurable defects stand out like sore thumb. The weirdest is that people hear (or claim to) the difference the superiority in transient load response of idler wheel drives compared to direct drives that show virtually unmeasurable changes under realistic loading. But direct drives have large poles (SP10 has 10 poles for example) so as to minimize the audibility and interference of their own cogging (10 poles puts it right at the sweet spot btw), but that doesn't by itself maximize the transient response, which would be maximized with a large number of poles per revolution--which is exactly what idler wheel drive has. Meanwhile, belt drives have decoupled motor which can't respond faster than the decoupling system--which works by making that response very low frequency and hence very slow. So it would make sense that people can hear these claimed differences, there are indeed differences like these there, but it isn't at all easy to measure them.

Shure and the like moving magnets work by using a LCR resonance to cancel out the frequency response error caused by an LR lowpass (not to mention damping other resonances). Well these resonances are not all strictly minimum phase, so though you can get everything to something like flat amplitude response, what it does in the time domain is messy. So measuring cartridge playback is not well done in obvious ways that people typically do. I remember J Peter Montcref dropped the stylus onto an unmoving record and analyzed with FFT. Well that's good in some ways, but it's noisy and inaccurate and doesn't even necessarily correspond to behavior around the stylus operating point. But it's pretty obvious that putting moving the stylus resonance from 16kHz (rhetorical hypothetical moving magnet) to 100kHz (good moving coil) is a good idea nevertheless.
 
The Real Steve Eddy,
You are correct that if the artist doesn't make sure that a recording is done well then all bets are off. But that is exactly Neil Young's gripe that the sound of his music is not what he hears in the studio and that is what he wants people to hear. I can't say anything about the implementation of the Pono player, that is to be seen.

That's not what I've gathered from what I've read. From what I've read, all he means by what's heard in the studio is that it's not MP3 being played in the studio. He's just been playing the numbers game, that's all.

se
 
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Does he have artistic control over how its mastered once he's finished recording? That would be a good place for him to start. But then is he saying what's heard on people's iPods doesn't sound at all like what he heard in the studio? If so that has nothing at all to do with having more bits than 16 and sample rates higher than 44k1. However there's no marketing initiative when that's acknowledged other than ditching S-D DACs and crappy analog stages - certainly no more revenue to be gleaned from music downloads.
:

I met with Neil Young on this project almost two years ago. He is really serious and he is not in it for the money. It has evolved since I met him and it seems to be going great guns- almost $5M in Kickstarter already. That impressive uptake on something that is still unknown. And 15K new customers introduced to the concept of quality audio. (That could double the market place in one shot.) If it crashed I suspect high end audio will be doomed to vanish with the boomers.

He is picky about audio quality and I would not want to be explaining to him why one of his projects was "remastered" into junk to sell it. Unfortunately there are artists and consumers who think the overcompressed fuzz that passes for music is the desired goal. Dynamics are scary to producers and possibly consumers. Perhaps listening on public transit or airplanes has changed the concept of silent background to low hum and rumble background that you need to mask with the music. And to a large extent music has moved from a rare and special experience to wallpaper to mask out the rest of the world.

Unfortunately he will not be able to get better quality content than others, like HD tracks, if it doesn't exist. He may be able to get the content owners to break out original analog masters for a fresh transfer if he can convince them there is money in it. What is still unclear is whether anyone (not a Pono user) can buy the tracks and play them on other systems. If so it would be great for the marketplace.

Can you give me an easy way to test the DAC for the "noise" you are talking about? I have the demo board for the ESS dac they are using. The ESS dacs measure really well (I am not a fan of the sound from them yet). Your condemnation of SD DACs seems to fly in the face of the resurgence of DSD as the preferred audiophile format. (One that Pono has not announced support for.)

For a little more than the Pono you can get the LG G2 phone which supports up to 192/24 on its audio outputs and is a very good smartphone. There are a number of other products focused on hi-res audio for mobile in Asia. I'm told that ESS is moving something like 100K of the mobile ES9018 a month in China. Really amazing is the $10 hit to the BOM for it on seriously price constrained products.
 
Can you give me an easy way to test the DAC for the "noise" you are talking about?

Curious - the scare quotes are because you don't think it exists? Have you seen the plots I've linked to and shown on my blog for the ESS? In particular the measurements of the Weiss Medea+? You'll need to look at the noise accompanying sine stimulus tones in the range -30 to -40dB wrt full scale.

I have the demo board for the ESS dac they are using. The ESS dacs measure really well (I am not a fan of the sound from them yet). Your condemnation of SD DACs seems to fly in the face of the resurgence of DSD as the preferred audiophile format. (One that Pono has not announced support for.)

No condemnation of S-D DACs from me, they just don't sound good to my ears. For a critique of DSD as an audiophile format, I can only refer you to Lipshitz and Vanderkooy's paper which to date hasn't been shown to be wrong in any important respects.
 
Shure and the like moving magnets work by using a LCR resonance to cancel out the frequency response error caused by an LR lowpass (not to mention damping other resonances). Well these resonances are not all strictly minimum phase...

How do you get an LR lowpass that isn't minimum phase? Ditto the LCR resonance. The equivalent circuits are not at all like an all-pass.
 
Thats called loss of transmission, if the signal ist translated into audible acoustical energy from the cartridge.

Non damped resonances in the cartridge body, non decoupled Headshells, ringing arm tubes, bearings and whatever you want, which means, the groove is not tracked proper.

The audible energy is also traveling somewhere in the chassis/arm Assembly.

I can assure you, my thingie is extremly quiet.

Important is also good distribution of the low freq resonances.
Suspended TTs should work around 3,5 Hz, Arm/ Cart. around 11Hz.
Significant deviation here comes in touch with warped records and or excentric records.
Motor cogging is also often in this area.

If we have problems in this area, ist very hard to get constant tracking weight and thus the resonances in the upper area can depend from the lower ones( modulation)

Thats why heavy arms and harder suspended cantilevers create lesser problems, when properly aligned.

Air bearing tangential means there is also an extrem low horizontal resonance, because the complete arm is moving left /right and vice versa, the vertical resoance is almost standard or somewhat higher since the arm is short.

BTW : To match the DL103 with the light arm carrying the grado, you will get non magnetic wights with a sticky tape from the guys in the car tire service center.
Looks ugly, works good and is easy removable.
I think you will need 7-10 gramms on top of the headshell and do not forget a heavier counterwight.
 
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Curious - the scare quotes are because you don't think it exists? Have you seen the plots I've linked to and shown on my blog for the ESS? In particular the measurements of the Weiss Medea+? You'll need to look at the noise accompanying sine stimulus tones in the range -30 to -40dB wrt full scale.

Actually its not noise but noise modulation you are referring to. Calling it noise makes it too simple and mislead me. I set up the multitone test you mentioned to see what I can discover. I did not find a smoking gun yet. The IM/HD products are below -115 dBC at every level I tried. They do change with level but the peak at -115 to none clearly identifiable above a floor of -125 at approx -36 to -37 dB drive seems pretty innocuous. I will need to do more work to make sure of what I'm looking at and further document it. If you have more ideas on catching this please provide them.

No condemnation of S-D DACs from me, they just don't sound good to my ears. For a critique of DSD as an audiophile format, I can only refer you to Lipshitz and Vanderkooy's paper which to date hasn't been shown to be wrong in any important respects.

You are talking about this paper: http://sjeng.org/ftp/SACD.pdf . They are very specific that a delta sigma DAC can be "perfect" if certain rules are followed and that a 1 level system cannot work. Finding ways to validate/prove this for the cognocenti won't be easy and there is a lot of push for DSD right now.
 
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I've always thought that is half the sound of playing vinyl.
Close the perspex cover on a turntable and half the 'magic' disappears.

Dan.

I have long been baffled by the need to put a sensitive electro-mecanical transducer in the direct acoustic field at high energy representing a delayed version of what is being transduced. Atomic force microscopes, which are the closest analog to a turntable in the industrial world are encased in elaborate acoustic chambers on very sophisticated vibration isolators: AEK-2002 Acoustic Enclosure I suspect a turntable in that environment would get much closer to the sound of a CD, meaning less life, duller dynamics, and constricted space. Certainly putting a turntable between the speakers really defies common sense.
 
BTW : To match the DL103 with the light arm carrying the grado, you will get non magnetic wights with a sticky tape from the guys in the car tire service center.
Looks ugly, works good and is easy removable.
I think you will need 7-10 gramms on top of the headshell and do not forget a heavier counterwight.

Thanks, since I golf the same stuff is available in thin stick-on form for club weighting.

Shhh, I also have 5 lb of bismuth shot (very slightly diamagnetic) to be lead free. A tweak in the making!

It is a quantum mechanical effect that occurs in all materials; where it is the only contribution to the magnetism the material is called a diamagnet. Unlike a ferromagnet, a diamagnet is not a permanent magnet. Its magnetic permeability is less than μ0 (the permeability of free space). In most materials diamagnetism is a weak effect, but a superconductor repels the magnetic field entirely, apart from a thin layer at the surface.

To be less ugly, there are very low melting point metals that could be mold
ed into cute shapes like hood ornaments.:clown:

I have a serious question, how do the H and V resonances on an ordinary arm get to be 3x different?
 
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Yes I've seen stories of folks with steel platters and thin felt pads have the cantilever crush itself on the first play (maybe urban legend).

If you use the cueing device to lower the arm, there is no problem.
While lowering it by hand, you just feel the increase of pull but it is OK.
The pull may damage the needle if the cart approaches the steel platter from the side and it is at record level or below. Fortunatelly, this kind of movement is allowed by only a few tonearms.
The magnetic pull affects the tracking weight. Zero the arm away from the steel platter. Rotate the arm over the platter and lower the cartridge. You will notice that the downward force is not zero there.

Re: test disks - In my view this is a coupled resonator problem if the H and V frequencies are different. Add the out of round and non-flatness exciters, do the disks do a good job of separating the two?

The test disks are good enough.
The problem is on the cart and arm. There are various coupled mechanical sub-systems that feed one the other, the final mix btn H and V occurs at the fulcrum of the cantilever due to it’s compliant construction.
If you have an old true monophonic cartridge with coils and mechanical construction outputing only the H signal, you may be able to form some good judgment (I don’t have one)


Playing an LP at 0 volume can still be quite audible.
:)

George
 

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