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His Master's Noise: A Thoroughly Modern Tube Phono Preamp
His Master's Noise: A Thoroughly Modern Tube Phono Preamp
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Old 14th June 2018, 09:49 PM   #511
frankwilker is offline frankwilker  Germany
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Hi jpjindex, i think you are right. Tell us your experience, when you are ready.
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Old 15th June 2018, 02:15 AM   #512
jpjindex is offline jpjindex  Brazil
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Quote:
Originally Posted by frankwilker View Post
Hi jpjindex, i think you are right. Tell us your experience, when you are ready.
Sure Frank... I'll do that.
Which cartridge and input transformer do you use?
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Old 17th June 2018, 10:08 PM   #513
frankwilker is offline frankwilker  Germany
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Hi,
my catridge is a Micro Benz Ruby Air III.
The SUT is a sowter 9580.
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Old 18th June 2018, 02:07 AM   #514
jpjindex is offline jpjindex  Brazil
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Micro Benz Catridge impedance = 40 ohms
Sowter 9580 ratio = 1:12.5

With R1=6k8 the cartridge was "seeing" only 42 ohms...

With R1=56K ~ 340 ohms or 8.5x its internal impedance
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Old 17th September 2018, 08:17 PM   #515
Arno Pf is offline Arno Pf  Netherlands
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Again a currrent source of the D3a died...overheating I suspect...getting larger cooling elements for them..

I saw on the opening topic photo's that there are no????? heat sinks at all...how can that be?
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Old 17th September 2018, 09:26 PM   #516
mrdave45 is offline mrdave45  United Kingdom
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Are you building the circuit on breadboard and measuring the current for that specific device or using the listed value. There can be be quite some variance between devices.
Is your multimeter within reasonable calibration? From what I remember you can run some of these tubes over a fairly wide range so a few milliamps out should still be OK, your problems suggests they're very out.
Are you also being careful of static? Don't build on plastic veneers! I learnt this the hard way with synthesiser circuits. Caused all sorts of problems. If you don't have an esd mat then put a wooden or mdf board down.
If you think all that's OK. Stick a heat sink on anyway.
Is the d3a 20mA? Of the 3 tubes I've used this cca on one was significantly hotter than the rest. I think the 6sn7 (impasse) was 8ma and I still put heat sinks on that.
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Old 17th September 2018, 09:44 PM   #517
euro21 is offline euro21  Hungary
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His Master's Noise: A Thoroughly Modern Tube Phono Preamp
Quote:
Originally Posted by Arno Pf View Post
Again a currrent source of the D3a died...overheating I suspect...
DN2540?
I killed a dozen of them (inrush spikes? fake batches from Mouser?) at using only over 300V.
Now I use IXTP01N100D everywhere (as "upper" FET of cascode CCS).
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Old 17th September 2018, 09:50 PM   #518
mrdave45 is offline mrdave45  United Kingdom
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Hmm that's interesting. I got mine from mouser but not had any problem. The hmn shoves a max of 260v into the cca for the d3a and I think the impasse has about (iirc) 350v but then drops a load across a resistor so I've not been taxing them like you have. Having said that, does the input voltage matter that much? Isn't it. The drop across them that's the issue. The reason I say this is the way voltage regulators work, they can be used at very high potential as long as the drop wasn't more than 30v or so?
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F4, Impasse, His masters noise, Troels Gravesen OBL15 and a stack load of analogue synths.
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Old 18th September 2018, 01:22 AM   #519
jackinnj is online now jackinnj  United States
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His Master's Noise: A Thoroughly Modern Tube Phono Preamp
Quote:
Originally Posted by euro21 View Post
DN2540?
(inrush spikes? fake batches from Mouser?)
I've been dealing with Mouser for over a quarter century and never got a fake component from them.
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Old 18th September 2018, 06:54 AM   #520
Arno Pf is offline Arno Pf  Netherlands
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Quote:
Originally Posted by mrdave45 View Post
Are you building the circuit on breadboard and measuring the current for that specific device or using the listed value. There can be be quite some variance between devices.
Is your multimeter within reasonable calibration? From what I remember you can run some of these tubes over a fairly wide range so a few milliamps out should still be OK, your problems suggests they're very out.
Are you also being careful of static? Don't build on plastic veneers! I learnt this the hard way with synthesiser circuits. Caused all sorts of problems. If you don't have an esd mat then put a wooden or mdf board down.
If you think all that's OK. Stick a heat sink on anyway.
Is the d3a 20mA? Of the 3 tubes I've used this cca on one was significantly hotter than the rest. I think the 6sn7 (impasse) was 8ma and I still put heat sinks on that.
Electronic eng, basics are in place and the D3a is indeed 20mA
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