Phono Preamps

[mediatechnology]

But I pretty much agree this P-10 is mostly over engineered

I dunno about that front-end being over-engineered. It just looks deceptively simple and clever to me. Particularly when made flat.

I've built a few 5532/4 based preamps too and they were fine. What about the 5532's high Ib flowing through the cartridge?

My motivation for digging up the old vinyl is certainly not for fidelity's sake. But, I have heard some performances of old songs that I had completely forgotten mixed out completely different than the CD version. Minus a few ticks and pops they're quite listenable.

I think it was Tomlinson Holman.

You and many others... between the 553x and 07x bifet you can cover most audio speed bases.

Still, even after 30 years and less than 50 cents each.

[ricardo]

Perfect is noiseless with infinite gain, etc.

NE5532 is effectively noiseless with infinite gain etc. for Moving Magnet RIAA.

It is remarkable how much effort designers put into getting RIAA accurate to 0.1 dB and then didn't bother to dial in cartridge termination capacitance.

Ditto. But there were certain guidlines which Frank Jones suggested in HiFi News, 70's and most MM cartridge manufacturers designed for these with the notable exception of Grado.

Tomlinson Holman? the APT guy, etc... He did one crazy ass design where the input LTP had a JFET on one side and a bipolar transistor on the other side... Interesting concept, but i never got comfortable enough with it to consider it in anything I ever did.

Don't think much about his designs but the Audio article is definitive on the performance requirements.

http://f1.grp.yahoofs.com/v1/gHldTuaW_G ... README.doc

Your link didn't open. for me.

Sorry. You need to be a member of the micbuilders Yahoo group.

I remember the oddball battery powered Leach head amp, and it was interesting but didn't float my boat as practical for anything.

Leach and the commercial copies were distinctly mediocre. One of my stripped versions had 0.28nV/rtHz using a grand total of 2 devices. I think it is still the quietest MC step up in the known universe when matched to a real MC cartridge. eg it was quieter than the huge & very expensive Denon transformer with their cartridges. With the Ortofon MCs, it was quieter than practically all MM cartridges into a good MM preamp.

But that's why I ran screaming from the high end audio business, decades ago. The sound of the hardware had precious little to do with anything.

You didn't tell them it was carved from solid Unobtainium by virgins.

[ricardo]

What about the 5532's high Ib flowing through the cartridge?

This was something that really concerned me in Jurassic times. There's no problem with Shure, ADC, Ortofon, Goldring and Grado, at least I couldn't measure any difference in distortion, tracking etc. on Test Records. What the high Ib does allow is a small, well defined offset to bias a nice Panasonic o/p electrolytic. This DOES affect the sound.

.. between the 553x and 07x bifet you can cover most audio speed bases.

I went off TL07x when I discovered the latching behaviour. But for NE5532/4, look at what Cyril Bateman used for his ultra low distortion buffers and oscillators. I'm only sorry you can't get NE5532/4 from the old Mullard/Philips factory in the UK. Sheesh! I'll be waxing lyrical about genuine Mullard EL34s and GEC KT88s next

[JR.]

You didn't tell them it was carved from solid Unobtainium by virgins.

When the selling proposition is based on BS there is little point to actually engineering the product above average. In fact subtle flaws gives them a sound difference to trumpet as better.

I instead gravitated to live sound reinforcement where you can't BS thousands of people at the same time... you must satisfy the laws of physics, not some jaded, coked out magazine editor.

JR

[mediatechnology]

This was something that really concerned me in Jurassic times. There's no problem with Shure, ADC, Ortofon, Goldring and Grado, at least I couldn't measure any difference in distortion, tracking etc. on Test Records. What the high Ib does allow is a small, well defined offset to bias a nice Panasonic o/p electrolytic. This DOES affect the sound.

So you actually looked at that? Wow, there's someone just as geeky as I am. Scary. Very scary. And, I've been getting these cards from the AARP...

OK, if you look at the Jung JW-33 the 100 uF does seem to be pointing in the right direction then with the - terminal to the OA output. The bias current of a 5534 should produce a negative potential across the cartridge coil since it has NPN inputs with current flowing into the part. The input stage is non-inverting. I suppose the extra DC component in the cartridge "tightens up the sound."

I think the original TAA article called for a 100 uF beaded Tantalum (rhymes with unobtanium) after the first stage LMAO. I have some of those. Priced them lately? I might be able to sell one and fill up the tank of my pickup truck and still have money left for lunch.

[JR.]

Sell....

[ricardo]

This was something that really concerned me in Jurassic times. There's no problem with Shure, ADC, Ortofon, Goldring and Grado, at least I couldn't measure any difference in distortion, tracking etc. on Test Records.

So you actually looked at that? Wow, there's someone just as geeky as I am.

This was early 80's. I'm really a speaker/mike man. I was hired by Calrec to do mikes, but I did far more electronics there cos that was where the money was.

My efforts with cartridges were far less successful. The brands I mention were those I could easilly (?) take apart & put back again. But I worked with Tony Emerson & Don Barlow who designed MC cartridges for LEAK in pre-Jurassic times.

I think the original TAA article called for a 100 uF beaded Tantalum (rhymes with unobtanium) after the first stage LMAO.

Jung was a pseudo prophet. He may have made exotic measurements of caps but he obviously never listened to them. Tants are evil. I've stripped every single Tant out of a REVOX A77 and replaced them with low leakage Al. electrolytics. Bateman is good on capacitors though I can't claim to have tried everything he did.

One of my specialties is integrating linear & non-linear electronics, DSP & speakers so the whole is greater than the sum of the parts. I call this Powered Integrated Super Sub technology but the Marketing Dept. never liked that.

The other is using Double Blind Listening Tests bla bla to design stuff. They like this even less cos it showed who was deaf.
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On supa OPAs for audio, it would be nice to have a FET i/p OPA with low offset & the performance of NE5534 but only AD745/3 springs to mind. I HATE ib cancelling OPAs. They invariably have poorer real life noise compared to OPAs that don't - cos correlated noise. If I can't get rid of the evil o/p electrolytic, I'm not interested in paying extra and the additional aggro sourcing.

And it would be nice to swing rail-2-rail in a battery app.

Many of the supa OPAs have nasty latching behaviour which they don't tell you about in the specs.

[JR.]

I want to experiment with the technique of transcribing LPs with flat preamplification and performing hiss, click and pop removal in DSP prior to application of DSP-based RIAA de-emphasis. People have reported good results doing it this way since the surface defects which cause clicks, ticks and pops are HF events. The reasoning is that it's easier for DSP applications to remove with less artifacts. I've used Virtos before on de-emphasized recordings and I'd like to see how it performs with RIAA equalization after Virtos.

This may require recording at reduced level, say -20 dB, to prevent overload. I have already obtained the RIAA de-emphasis filter files for Cool Edit 2000. What do you suppose would be a reasonable preamp gain if there is no RIAA de-emphasis using a typical MM cartridge?

I just had another thought that might be interesting. Using some non-real time magic, modify your turntable to playback at half speed before the de-pop/click step. Even at slow speed the clicks and pops will still be HF events, but further away from real audio signals. As long as the speed is restored to normal before RIAA playback EQ this could work.

Tricking the turntable speed may be a hard or easy depending on the turntable.

JR

[mediatechnology]

Worth a try. I think I could also transcribe in real-time (avoiding turntable mods), render the soundfile in half-speed, de-click, then double the speed.

I have some of the Original Master Recordings where they mastered in half-speed.

[JR.]

Worth a try. I think I could also transcribe in real-time (avoiding turntable mods), render the soundfile in half-speed, de-click, then double the speed.

I have some of the Original Master Recordings where they mastered in half-speed.

That would not be the same IMO. I am thinking that there are mechanical resonances associated with the cartridge responding to surface flaws that would decay at similar time constants despite scaling the audio frequency down, so mechanically playing at half speed then speeding up, could shorten the click perturbations even more.

Of course this is just a theory so who knows?

JR