LT1115, like AD797, is practically ideal for your DL110 (160R DC). Except for the EVIL Ib cancelling
They are poor for the usual MMs or the usual LoZ MCs .. which some famous name designers on this forum haven't figured out.
Most MCs have more POWER output than MMs though their lower voltage & resistance) needs to be matched and hardly any stuff does this properly. The inductance in a MM also makes it impossible to 'match' them for noise.
Denon DL110 has about 1dB more power than Ortofon MC20 which (if properly matched) has at least 3dB S/N advantage over the Ortofon MMs and even more over the best SHUREs of the time.
This 4dB more power in DL110 means you can probably equal or better a MM for noise .. even in the usual MM preamp that's (or should be) optimised for the inductance of MM.
You need to increase the gain for DL110 and do it in a way that reduces Ein rather than increase it.
BTW, if you are doing BLTs between cartridges, you need to get the levels matched to better than 0.5dB .. preferably better than 0.2dB. (Difficult to do Double Blind on a vinyl playback system.
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Can't remember. It was 25+ years ago.Zero D said:
But if there was a Golden Pinnae (or other) input cap, I would have removed it. I HATE any bits on a production item that doesn't give better performance and/or reliability. I've had young engineers on the carpet when their 'new' designs had more bits that the product they were replacing.
An OP27 is really a 5534 with EVIL Ib cancelling added .. so this was no surprise. Check out the internal schematics from the old datasheets.
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That seems to echo what I found. I could give a list of other DL110 traits I like. One which I take to be true is that it is insensetive to temperture differences, or more so than most.
There were some MM cartridges made with low output that were more like MC. Did anyone try these? I often wondered if the humble AT95 with fewer turns would have been interesting. Target output about 800 uV at a guess.
Is it true to argue that a JFET input is much like having a blocking capacitor in the device? I have always assumed this. If so Douglas could try to find an optimum JFET device to use ( MC/MM ). I totally like the idea of NE5534 as a reference device. BTW. The MC33079 I like is now about 16 pence at RS in SMD. 4 op amps that in some ways please me more than 5534 is not bad for 1/3 the price of a cigarette in the UK.
There were some MM cartridges made with low output that were more like MC. Did anyone try these? I often wondered if the humble AT95 with fewer turns would have been interesting. Target output about 800 uV at a guess.
Is it true to argue that a JFET input is much like having a blocking capacitor in the device? I have always assumed this. If so Douglas could try to find an optimum JFET device to use ( MC/MM ). I totally like the idea of NE5534 as a reference device. BTW. The MC33079 I like is now about 16 pence at RS in SMD. 4 op amps that in some ways please me more than 5534 is not bad for 1/3 the price of a cigarette in the UK.
Personally, I always use a coupling cap. For the most part the other side of the cap is connected to a fairly high resistance source so you don't get huge current transients through the cartridge winding on switch on. Further, if you do, then you'd have exactly the same problem without the cap as well, surely?
If the front end pops (not unheard of) then at least with a cap you won't have 15 V or whatever you are using across the cartridge indefinitely. Lets think about the consequences of that on a $500 or more device - not nice.
I am using 100uF 25V bipolar in parallel with a 0.47uF film cap.
If the front end pops (not unheard of) then at least with a cap you won't have 15 V or whatever you are using across the cartridge indefinitely. Lets think about the consequences of that on a $500 or more device - not nice.
I am using 100uF 25V bipolar in parallel with a 0.47uF film cap.
LT1115, like AD797, is practically ideal for your DL110 (160R DC). Except for the EVIL Ib cancelling
An OP27 is really a 5534 with EVIL Ib cancelling added .. so this was no surprise. Check out the internal schematics from the old datasheets.
Ib comp has no effect for MC, even you can compute the noise of 2pA into 15 Ohms.
And no the OP-27 bears little resemblance to a 5534. The real not simplified schematics have both been published.
Talking power transfer/mathching and carts is problematic. A MC works fine into a FET pre-amp made with massively parallel BF862's for instance (I've seen .3 nV versions) delivering no power to the load.
EDIT Our former member .3nV with only 8 parallel, down near bottom of page. Oh yes, no coupling cap either.
http://www.synaesthesia.ca/LNschematics.html
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"Oh yes, no coupling cap either."
Sure as hell hope
Have anyone ever heard a report of a spontaneous preamp input fault ever destroying a cart? I'm sure its happened at least once in the history of the world but the odds of the turntable being hit by lightning are greater.
More likely a repair tech shorted the rails across the cart and blamed the lack of cap.
A mate of mine powered up his mc-preamp with reverse polarity and burnt out 1 coil in his Monster Alpha cartridge. A real shame, it is (was) a terrific sounding cartridge.
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Actually easy to test! The resistance of a copper wire usually doubles just before failure. I do have a Denon cartridge missing the cantilever. If I get the time I can burn it out while measuring the current. In practice a surge would have to be higher than a slowly increasing power level.
LT1115, like AD797, is practically ideal for your DL110 (160R DC). Except for the EVIL Ib cancelling
An OP27 is really a 5534 with EVIL Ib cancelling added .. so this was no surprise. Check out the internal schematics from the old datasheets.
Point taken.Ib comp has no effect for MC, even you can compute the noise of 2pA into 15 Ohms.
But surely you aren't recommending OP27 for either DL110 (160R DC) or LoZ MC (15R) or even MM? You have much better designs, like eg AD797, for DL110.
I knew it!! AD gurus of old spoke with forked tongue
The 'power' calculation ... V^2/Rdc ... is a measure of potential S/N. It is valid whether the load is matched or not. It's the same calculation that determines the S/N of dynamic mikes or ribbons and again independent of the load.
Most MC are potentially quieter than most MMs. Whether this potential is realised depends on loadsa stuff .. most of which are rarely done.
My MCamp.doc on my Yahoo MicBuilder's files, sez ..EDIT Our former member .3nV with only 8 parallel, down near bottom of page. Oh yes, no coupling cap either.
This is what prompted me to re-visit noise performance. A cursory look at these very detailed pages suggests he’s finally achieved my 0.28nV/rtHz performance. Closer examination says some of his noise measurements are wonky and I don’t believe his rbb’ figures at all. He does mention some of the things which need addressing though there is no need to adopt his supa methods. The bottom line is his slightly (??) more complex circuit is not as quiet and probably has more THD with real MCs. Overload recovery probably OK.
I get my 0.28nV/rtHz with a grand total of 2 devices. Wayne has dug up some new devices that may allow me to use even less Guru Wurcer points out that his AD524 IA is practically ideal for MM and could replace loadsa bits in your balanced input MM playback system
Sadly, I'm not sure even this simplification will persuade Doug to pontificate on balanced inputs in his new vinyl preamp book.
Da really useful info from this would be the identity of the c**p preamp that allowed this to happen.
Maybe slightly more likely than your preamp being struck by lightning but not a lot .. unless it was a DIY effort in which case anything goes
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There's actually a big disadvantage of the input cap(s).
It's physical size .. especially for MC means the input loop is a LOT bigger with the potential to pick up hum, buzz & RFI.
But Doug is going to show us how to get all this yucky stuff unmeasurable with simple unbalanced topologies .... and with his beloved input caps too.
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Well I could really take offence at this as the c**p preamp was one of my designs.Da really useful info from this would be the identity of the c**p preamp that allowed this to happen.
Maybe slightly more likely than your preamp being struck by lightning but not a lot .. unless it was a DIY effort in which case anything goes
The problem was, the power supply was 2 SLA batteries wired to give +/- 12volts and my mate applied the power leads back to front. An expensive error for which I take no responsibility.
What I would like to see in a book on vinyl replay - these are all things I've been playing with lately:
- balanced input/ balanced eq. for magnetic cartridges
- loading for m-coil cartridges
- common base inputs for m-coil cartridges (I haven't tried this yet, when I get a few days off work I want to see if I can modify my m-coil pre-amp to try this)
- gain stages for displacement devices. Balanced and single ended, and equalisation requirements (I know what the theory says, but my WIN strain gauge doe NOT need eq).
- the truth behind the 50k time constant
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