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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 23rd August 2019, 05:17 AM   #1371
Boydk is offline Boydk  Denmark
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Originally Posted by Hans Polak View Post
I just entered a test order.
No warning, no box that I could check.
I’m afraid that in the Dutch translation on the Digikey site this box got lost, or it is hidden somewhere deep down inside where nobody ever comes.

Hans
Hans.... it´s in the end of ordering, where you have the possibility to change the shipping. The standard (where mouser takes care of the import duty charges) is always chosen by default. To Denmark they ship by UPS. You can choose different shipping methods, but other than the standards you yourself are in charge of the import duties.
Must say, that they recently have cleaned up their act. They used to have all kind of fees and charges sometimes close to fraud (not DigiKey but the shipping companies, specially FedEx and UPS). Now is a different story. In my last shipment, I was notified by a tracking update e-mail, that I had chosen to pay import duties and that i could pay online 66 DKr (10u$). No brokers fee, no extra charges for handling... just the 10 bucks. Very pleasant to do business with them both. The reason for me to choose DigiKey is, that Mouser ships by default using FedEx, and that company (in Scandinavia at least) is the least flexible of them all. Here DHL Express and UPS are flawless at their service
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Old 23rd August 2019, 06:26 AM   #1372
fasterbyelan is offline fasterbyelan  United Kingdom
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Richard Lee's Ultra low Noise MC Head Amp
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Originally Posted by Bonsai View Post
That’s weird. I’m using RS, Mouser and DK here in the UK and never get that issue - all duties and transport costs always included.

.
The same for me, Mouser is now my prefered option. I have found that prices are similar to Farnell but they hold a wide range of parts; delivery is always within two days.
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Old 24th August 2019, 02:21 PM   #1373
gerhard is offline gerhard  Germany
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Originally Posted by syn08 View Post
Same here, two pencils, but I'm still planning for the precision tweezer hand piece MX-PTZ, later this year.
BTW, the tips are hard-grounded, not just the anti-static Meg. Killed a transistor
yesterday for being too lazy to switch off the power. I touched the wrong side of a resistor.
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Old 26th August 2019, 01:01 AM   #1374
kgrlee is offline kgrlee
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Quote:
#375's gain is limited by R4 & 5, which feed the current mirror and appear in parallel with the output resistor R7.
Quote:
Originally Posted by syn08 View Post
Nope. #375 gain is limited by the power supply voltage. It is independent on R4/R5.
Duraglit has a similar 'limitation' with supply voltage.

But at the high gains which seem to be of most interest to herve00fr, Duraglit has some 40dB more gain potential than #375
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Old 26th August 2019, 02:53 AM   #1375
syn08 is offline syn08  Canada
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Originally Posted by kgrlee View Post
Duraglit has a similar 'limitation' with supply voltage.
Nope, it is completely different in this respect. The gain depends on the load and the bias resistors.
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Old 26th August 2019, 01:22 PM   #1376
herve00fr is offline herve00fr  France
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Quote:
Originally Posted by syn08 View Post
Nope, it is completely different in this respect. The gain depends on the load and the bias resistors.
And the bias resistors depend on the supply voltage.

Quote:
Originally Posted by kgrlee View Post
But at the high gains which seem to be of most interest to herve00fr, Duraglit has some 40dB more gain potential than #375
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Old 26th August 2019, 01:33 PM   #1377
syn08 is offline syn08  Canada
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To add insult to injury, too much gain in the head amp is bad for the overload margin. IMO, anything between 15dB and 30dB is good enough, no need to go for more. 40dB or more of gain would also challenge the MM input the head amp is supposed to connect.
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Old 26th August 2019, 01:52 PM   #1378
Bonsai is offline Bonsai  Europe
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Originally Posted by herve00fr View Post
And the bias resistors depend on the supply voltage.
Herve, what models are you using here? Your noise figures seem to good to be true.
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Old 26th August 2019, 02:28 PM   #1379
herve00fr is offline herve00fr  France
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Quote:
Originally Posted by Bonsai View Post
Herve, what models are you using here? Your noise figures seem to good to be true.
In real life, I use 2sk369V instead of 2sk363.
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Old 26th August 2019, 02:39 PM   #1380
herve00fr is offline herve00fr  France
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Originally Posted by syn08 View Post
To add insult to injury, too much gain in the head amp is bad for the overload margin. IMO, anything between 15dB and 30dB is good enough, no need to go for more. 40dB or more of gain would also challenge the MM input the head amp is supposed to connect.
It's diy, you can lower the gain of the MM RIAA preamp.
For very low noise purpose, high gain in the first stage is mandatory.
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