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Richard Lee's Ultra low Noise MC Head Amp
Richard Lee's Ultra low Noise MC Head Amp
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Old 19th June 2019, 03:32 PM   #31
syn08 is offline syn08  Canada
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Originally Posted by scott wurcer View Post
I guess there could be an issue with one size fits all, but I always try to set the gain for the cart in use.
That's probably part of the disagreement. DIY, no problem tailoring for your very own cartridge. A product, not so much, at least without a very expensive solution (recall JC gain wire wound gain pot). Providing a large overload margin is definitely cheaper.
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Old 19th June 2019, 03:42 PM   #32
billshurv is offline billshurv  United Kingdom
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Richard Lee's Ultra low Noise MC Head Amp
This IS a DIY forum after all. Doing things that could never be commerical products is where the fun is for me. A couple of transistors at the turnable phantom powered in a focusrite Scarlett is a potentially neat way of side stepping a lot of problems that analog front ends can have. A lot of people do rip vinyl. In fact some buy an LP and only play it once.



All good fun, and no bybees were hurt in the process
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Old 19th June 2019, 03:45 PM   #33
mlloyd1 is offline mlloyd1  United States
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Richard Lee's Ultra low Noise MC Head Amp
billshurv:

what a great "coke-spitter" that was.
i'm still wiping my keyboard

mlloyd1

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...

no bybees were hurt in the process
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Old 19th June 2019, 04:10 PM   #34
syn08 is offline syn08  Canada
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Originally Posted by billshurv View Post
This IS a DIY forum after all. Doing things that could never be commerical products is where the fun is for me.
Of course, I was only trying to figure out where Tom Holman's opinion was originating from. TH didn't strike me as a DIYer .
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Old 19th June 2019, 04:41 PM   #35
billshurv is offline billshurv  United Kingdom
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Ah no, I get you now
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Old 19th June 2019, 05:00 PM   #36
scott wurcer is online now scott wurcer  United States
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Originally Posted by syn08 View Post
TH didn't strike me as a DIYer .
No, but I wish he normalized all his data to one standard. Taking his last (worst case) graph I get 120mV for my 4mV cart, which is actually no problem except at the low end (maybe).

I wish there were more discussions of gain structure and overload margin, folks still complain when they use a miniDSP in front of their 106dB sensitivity speakers and find it noisy. They are running everything throwing away bits to get the output level low.

There is also the issue of overload at the input vs the output. I still don't see the point in specifying a line stage at 10V rms out when any normal 100 or so Watt PA would be hard railed at 3-4V.

Another thing about Mr. THX he talks about intermod with warp and LP eccentricity but this is not a pre-amp issue except in the extreme. The damage is done by the tracking angles and effective velocities changing, no amount of low pass filtering can fix that.
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Last edited by scott wurcer; 19th June 2019 at 05:05 PM.
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Old 19th June 2019, 05:10 PM   #37
syn08 is offline syn08  Canada
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Originally Posted by scott wurcer View Post
There is also the issue of overload at the input vs the output. I still don't see the point in specifying a line stage at 10V rms out when any normal 100 or so Watt PA would be hard railed at 3-4V.
Yeah, there is though a good reason for that... traditionally, power amplifiers have clipping protections/flashing indicators/etc... Preamplifiers, not so much. It's probably a good idea to have a "single point of clipping", once again, from a consumer perspective. Of course, this is no good reson to feed a preamp at +/-24V and to make it almost rail-to-rail output (like, ahem, the Blowhard preamp).
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Old 19th June 2019, 05:59 PM   #38
Bonsai is offline Bonsai  Europe
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10V RMS Line stage OL is specmanship IMO. 2V RMS out will cover just about anything on the planet. But I think if you offered a product that overloaded at 2 or 3V out, you would get flak for it. Some things are best just left where they are. That said, the distortion sweet spot on a lot of gear is the 2-3V output level - just look at the AP plots on Stereophile of the more sensible stuff.

With overload and the phono EQ, you have the volume control normally between the EQ OP and the power amp or line stage preamp so having good OL on the EQ amp allows you to essentially adjust the signal chain gain at a convenient place to fit the program material dynamics.

Even for DIY preamps, I'd still design the phono stage for good OL.

(separately, I've just been loaned a Hanna ML moving coil cart - absolutely superb and a big step up from the Ortofon Red I've been using)
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Old 19th June 2019, 06:03 PM   #39
jackinnj is online now jackinnj  United States
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Richard Lee's Ultra low Noise MC Head Amp
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Cables are also very microphonic - I suspect better quality noes with decent insulators are better in this regard. If you move them around they squeak and make all sorts of popping sounds at these amplification levels.
The physical movement of two dissimilar insulators causing charge to move. Tribolectric effect.

Testing for it by the folks at Molex:
Triboelectric Noise in Medical Cables and Wires - The Connector: By Molex
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Old 19th June 2019, 06:10 PM   #40
syn08 is offline syn08  Canada
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(separately, I've just been loaned a Hanna ML moving coil cart - absolutely superb and a big step up from the Ortofon Red I've been using)
Bohoho, waa, waa, sob, sob, nobody is in a rush to loan me such expensive stuff . That must be one great cartridge.
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