I think that i saw this explanation 100 times ...but Most and Considerably is no equal to All ...so overkill sells to those who really want overkill circuits and usually you start of thinking about overkill ones after being bored with the others...As i allready said, that AIWA c22 current feedback transimpedance preamp sounds Really Well compared to any other phono preamp that i built or heard in the last 5 years, while it is only a transimpedance amp supplied with +-15v. Yet you might really Consider the phono preamp in the attachment one of the best solid state phono preamp ever made for good reasons but that is only if you have the whole Kenwood l-02 amp and really good and powerfull speakers because that preamp has real Slam! Of course it has some cascodes that need higher voltage supply...some op-amps have cascodes inside too. I'm not here to argue about overkill vs good enough circuits, i'm absolutely sure that overkill designs have the potential to sound better than usual ones, while there's no evidence that an "usual" cheap design can't be better than many of the "overkill" ones .If you simply consider a valve vs solid state...you can make a very good phono preamp with just two valves , or with just two fet transistors, nothing less than three bipolars will work properly , ten's or hundreds of transistors per op-amp, but they will never be equal in virtues and nothing guarantees one being better than other.
Most of the guys in the "overkill team" think that 40db headroom is what you really need for a phono preamp. If you think about the compresssors or the soft clipping circuits (valve or solid state) they are here for a reason.In the recording industry you can have a soundcard supplied by +-12v that can handle anything just because of those soft clipping circuits before the ADC and here's the art of making cheap recording sound cards, not in the best headroom or infinite linear response. As somebody said in another topic, 24 bit is pretty much useless at recording with microphones when the background noise ask you to go beyond a jet aircraft noise if you really want the benefit of the 24 bit dynamics. ...
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Most of the people who claim they need 40dB overload margin have never bothered actually logging things off their vinyl to see what is needed and just repeat what the last loony said.
I am happy you like your AIWA although one contemporary review of the whole microsystem says 'Although each component performs surprisingly well, it’s the preamp that lets the side down'. For me it fails at the first hurdle with a 47K load. That's not the way I do MM interfacing anymore.
But this thread is about the TI app note phono.
I am happy you like your AIWA although one contemporary review of the whole microsystem says 'Although each component performs surprisingly well, it’s the preamp that lets the side down'. For me it fails at the first hurdle with a 47K load. That's not the way I do MM interfacing anymore.
But this thread is about the TI app note phono.
The aiwa preamp was the only one to convince me that an active design can be good enough...And anyway, the input impedance of that lm4562 in open loop is still 30kohms, the current noise is still higher than ne5532 and headroom still counts...
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I am sure it has. It's however not what Hiten and the OP have. And I have OPA1632 for MM duties with the cartridge loaded at around 150Ohms.
I wonder what mm cart will take 150 ohms...I personally don't really care of what others say about audio equipment, it's only my ears and oscilloscopes that listen to it.
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AT150MLX Dual Moving Magnet Cartridge (DISCONTINUED) || Audio-Technica here it says that you need 47kohm minimul for load, not 150 ohms...it's mm cart not mc...I have Ortohon OM 5...it's loaded normally for an mm cart...
You said you like transimpedance amplifiers. So consider one! Think about what happens as you decrease load towards zero and it starts to become a true transimpedance* stage. Only by really thinking out the box will you make progress to a better phono stage.
*Hint the other name for transimpedance is I/V converter.
Sorry to everyone else I'll go back on track now.
*Hint the other name for transimpedance is I/V converter.
Sorry to everyone else I'll go back on track now.
The overload margin of this TI design is well over 20dB -- at least in simulation, even with 12 volt rails.
When I transfer from vinyl to digital I use Audition -- on old recordings hitting a tiny bit of dust is like hitting a boulder with your car -- I wonder what some of those 1960's LPs would look like with potato chips and dried soda baked into the grooves.
Ok...i understand now...i didn't really put together these bits of information you've thrown out at me in real time . So you load this AT cart with 150 ohms and use this chip basically in open loop with it's 70db open loop gain...You must have gone this way if you really want to properly compensate that cartridge:
Website of Wayne Stegall - Phono Equalization Calculations http://waynestegall.com/audio/spice-models/riaa/riaaci2st-psps.txt
US4470020A - Virtual ground preamplifier for magnetic phono cartridge
- Google Patents
The only problem with current to voltage converters is that mm cartridge aren't great at givin' enough current...which makes for the fact that the SNR isn't really great when using this technique with mm cartridges.
By the way...the last patent link might show the internal guts of AD844...
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He was totally wrong on the damping front (someone here has tried it).
Not open loop at all. If the load is non zero it starts to look like a std inverting amplifier.
MM are fine at giving current and the SNR is superb. Sims that Hans Polak did show SNR around -76 to -80dBA WITH THE CART CONNECTED. All plots are on here if you look. Huge bandwidth, low noise, great overload. Never caught on for many reasons but once a decade or so someone dusts it off and tries it. It's good.
Not open loop at all. If the load is non zero it starts to look like a std inverting amplifier.
MM are fine at giving current and the SNR is superb. Sims that Hans Polak did show SNR around -76 to -80dBA WITH THE CART CONNECTED. All plots are on here if you look. Huge bandwidth, low noise, great overload. Never caught on for many reasons but once a decade or so someone dusts it off and tries it. It's good.
Thanks for the info!They're not wrong.The guy in 1984 actually built that thing based on v15type 3.You can do it with an Ad844 today.I will read the whole topic made by Hans! The idea of using op1632 for phono was first given by Thorsten...i read the article back then...Yet i can't believe in any way that 150 ohms is a realistic load for the AT cart.The load can't be smaller than the dc resistance of the cart coil.
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No I mean you cannot electrically damp a cartridge. Doesn't work as the generator is too inefficient. The whole 'stylus stabiliser' claims are bogus. But he got the important bits right.
I used to verify spice syms with the reality and they get it right most of the time, or at least very near to the real thing.The basic theoretical calculations done by these two guys should be accurate and Lentz rule never changed...People are lazy and never read the spice directives, but Wayne Stegall actually give you the real values for the circuit as well...I never saw a public comment on his work.He was the first to mention the work of Daniel R Mohr, but he never gave a name, just mentioned the year of the patent so i found it with google. Website of Wayne Stegall - Phono Equalization Calculations. At least until proof will be given against it's calculations i will keep his work as a priority to check within the course of this year.I never doubt the math guys as i know no math at all.
you should check out the muffsy phono pre. it's based on the CNC design and provides information on how to set gain for this topology
https://www.muffsy.com/phonostage-gain.html
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