Thanks....yes I have a real problem with it....low gain and insufficient high frequency response (dull)
Many thanks Mooly. I'd love to see your attached file but cannot open the .asc file even after downloading a few apps that should work
The first stage will clip first at the high frequencies due to the "rising with frequency" output from the MM transducer. Raising the gain of the first stage will reduce the overload margin at those higher frequencies. After the first stage, the RIAA network will attenuate all frequencies but with more attenuation at these higher frequencies and provide a level response before the signal is applied to the second stage and also result in an evenly distributed overload margin for the second stage.
The RIAA network -- while the values are correct such as they are, no consideration was given to the noise of the network given the high value buildout resistor.
There us no chance of clipping the input as 500mV is required. Surprised the riaa is out by 20 plus dB on the low end. I matched my preamp to a CD copy of Fleetwood mac the EQ change is to the top end response. 20hz to 2khz follows RIAA curve 0.1db
Are you actually using the LM4562? A quick perusal of Self's 'Small signal design' will show that the current noise of the 4562 makes it just about the worst choice possible for MM stage. In this application, it's even noisier than the 5532, let alone 5534 - which is vastly quieter.
In my own experiments, I've found that higher source Z doesn't only exacerbate the 4562's popcorn noise issue (still here, even in batches purchased in 2022), but even affects its stability. When I first got samples of the 4562 around 2008/9, I seem to remember that trying it in a phono stage created a cyclic instability, that was solved by swapping it for an OPA2134 (same slew rate if I recall).
I suspect you could pick a randon dual OA and it'd be better than the 4562 for MM phono input noise-wise. I'm quite staggered that Ti would've suggested it in the apps data. It really doesn't like those kind of source Zs. With low source Z (and careful vetting, for the popcorn problem...) it's stellar, and can give figures that will challenge all AAs bar top-of-range AP / R+S.
In my own experiments, I've found that higher source Z doesn't only exacerbate the 4562's popcorn noise issue (still here, even in batches purchased in 2022), but even affects its stability. When I first got samples of the 4562 around 2008/9, I seem to remember that trying it in a phono stage created a cyclic instability, that was solved by swapping it for an OPA2134 (same slew rate if I recall).
I suspect you could pick a randon dual OA and it'd be better than the 4562 for MM phono input noise-wise. I'm quite staggered that Ti would've suggested it in the apps data. It really doesn't like those kind of source Zs. With low source Z (and careful vetting, for the popcorn problem...) it's stellar, and can give figures that will challenge all AAs bar top-of-range AP / R+S.
First put bigger caps, 22 uF, and +/- 12V rails, see what happens.
Then change out the chip, put a socket, and do the op amp rolling bit till you are satisfied.
TL072 was chosen for my build because it is cheap, easy to find, and has enough slew rate (above 8 is enough for audio).
Proper techniques of termination, grounding, shielding and so on also matter, I got RCA cables without shield continuity, had to exchange them, they were the noise source.
Then change out the chip, put a socket, and do the op amp rolling bit till you are satisfied.
TL072 was chosen for my build because it is cheap, easy to find, and has enough slew rate (above 8 is enough for audio).
Proper techniques of termination, grounding, shielding and so on also matter, I got RCA cables without shield continuity, had to exchange them, they were the noise source.
Indeed. When Nat Semi's team still had the great Mr Pease at the helm, which makes its inclusion even more incredulous! I totally get why they would've wanted to maximise its market potential (they even suggested a tape head amp), but considering it's easily outperformed by an IC that came about 30 years earlier (5534), it does seem odd to me that it'd be included without raising a few eyebrows.
Any opinions about quality of same devices made by different suppliers?
The consensus seems JRC is better than TI, which in turn is better than ST, so the chips should be chosen in this way for builds.
The consensus seems JRC is better than TI, which in turn is better than ST, so the chips should be chosen in this way for builds.
I once visited NS and had a chance to peek into bob pease´s cubicle. no way in hell he would be in the management of NS.
If JRC make a version of 49720 / 4562, then we will all be happy!
(that's not actually a joke BTW. I think Ti is approaching Vishay levels of hegemony, and it can only be a bad thing for consumers)
(that's not actually a joke BTW. I think Ti is approaching Vishay levels of hegemony, and it can only be a bad thing for consumers)
it is often specmanship, and TI is good at hiding the not so good values. especially when it comes to noise with HighZ capacitive sources like photodiodes, the common mode parasitic capacitance is a big contributor. I ended up better using a non-RRI from analog even though the specs sounded better of the competitor.
Many RIAA preamps only give 200-300 mV output with 5mV input at 1kHz. They then feed a line stage with 10-15 dB overall gain so the final result is 45-50 dB gain before feeding a power amp.
Thanks very much geoff...I was completely unaware of this software. I've just downloaded and will start to learn how to use it...very much obliged 🙂
The NJM4562 is not the same IC! But you can bet that most of them give the same specs, unlike the LM4562, where around 30-40% have various degrees of burst noise!
Bassreflex makes a good point re: Ti massaging specs. Several conversations broke out at Ti's groups re: burst noise. They said nothing and locked the threads. It was then noticed that the noise specs were revised to show noise spec BW above 400Hz!
Bassreflex makes a good point re: Ti massaging specs. Several conversations broke out at Ti's groups re: burst noise. They said nothing and locked the threads. It was then noticed that the noise specs were revised to show noise spec BW above 400Hz!
Here NJM series (JRC) parts sell for double price compared to TI and ST...just saying, must be superior quality.