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Old 4th July 2011, 10:48 PM   #2371
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They are the transformers sans the 230V cables. Yes, this stage is suffering from some juice.
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Old 5th July 2011, 02:23 AM   #2372
tvi is offline tvi  Australia
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A bit late, may still be of interest
Takman Resistor Audio Patent

Quote:
A resistor 1 is used in high-fidelity amplifiers for audio equipment. The resistor 1 includes a cylindrical resistor body 2, a tubular sheath 3 into which the resistor body 2 is coaxially inserted, and a conductive film portion 31a formed on the inside surface 3a of the sheath 3. The conductive film portion 31a faces to a resistance film 22 covering the surface of the resistor body 2 with an annular space 6. An insulating slit 32 is formed at a central point along the resistor axis 1a, separating the conductive film 31 into left and right parts that are electrically isolated from each other. The sheath covering the resistor body 2 prevents distortion of signals in the resistance film 22 caused by extraneous electrostatic induction charges.
Doesn't mention endcap/lead material

Stax Audio Resistor took a very different tack

Rgds
James
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Old 5th July 2011, 07:43 AM   #2373
MiiB is offline MiiB  Denmark
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The TAKMAN RTM are capless MELF resistors....But what kind of contacting they have made I am not sure about, as the PDF datasheet does not tell in english...and I cant interpret the Japanese...(could Google translate it, but info is in a graphics file so not translatable)

http://www.takman-e.co.jp/pdf/rtm.pdf
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Old 5th July 2011, 08:54 AM   #2374
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One possibility is buying some and try with a magnet.
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Old 5th July 2011, 09:26 AM   #2375
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Quote:
Originally Posted by MiiB View Post
info in graphics file
The middle parts reads 'metal', the first and last parts in traditional Japanese are not clear enough to make out.
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Old 5th July 2011, 09:59 AM   #2376
MiiB is offline MiiB  Denmark
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I'am sure its not iron or steel based...more like nickle copper or tin..that can be plated on the ends for form a solder-able contact layer.

not sure about the nickle sound-vise. as the tests i have done with my loudspeaker terminals clearly indicate that nickle as a barrier layer under gold is not as good as gold without the nickle...

but surely removing the magnetic eddy-current creating steel-endcap on the MELF will be a good thing...and to my limited knowledge surely better, regardless of the possible nickle use...

Last edited by MiiB; 5th July 2011 at 10:12 AM.
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Old 8th July 2011, 11:34 AM   #2377
hesener is offline hesener  Germany
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Default watch this.....

Hi, in the process of building my Hi-Z FPS phonostage, and when doing some initial testing I stumbled across something quite interesting. Attached IR pictures show that the 8x NE5534 have quite different temperatures, ranging from 41C to 57C (!) with no signal.
Datasheet says their idle current is 4...8mA. No oscillations observed (of course I checked). Then I swapped two opamps, and the temperature stayed the same for the same opamp, meaning it has nothing to do with the design or the PCB. (check out the lower righthand corner of the attached pictures where the opamps were swapped, all others stayed where they were)
Now, given that theses guys now operate at vastly different temperatures, may that have an impact on the paralleling, the balance of the circuit, the sonics? Don't know.... Have 30pcs on order and when they are here I will stuff one channel with matched opamps, the other one with unmatched, and do some comparison...

Anybody ever came across that issue? I'm a little puzzled...
Attached Images
File Type: jpg IR_0225.jpg (26.6 KB, 310 views)
File Type: jpg IR_0227.jpg (27.2 KB, 305 views)
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Old 8th July 2011, 11:40 AM   #2378
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Interesting! Possibly the varying supply current is the cause; a variation of 1:2 in dissipation must have a temperature effect. Although I wouldn't expect many showing the max of 8mA.
Maybe use different opamps from your stock and see if the variations remain as high.

Edit: The thermal R for a DIP08 is about 60 degrees / W IIRC, so your 16 degr delta temp could be caused by about 0.25W dissipation difference.
Taking a delta supply current of 4mA with +/-15V supplies would give a delta dissipation of about 0.12W so can only explain half of the 16 degrees temp difference. Hmmm.

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Last edited by jan.didden; 8th July 2011 at 11:50 AM.
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Old 8th July 2011, 12:34 PM   #2379
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Makes me wonder how images of me Mr Self amp would look like, unfortunately i don't have a Flir yet.

(ah, such a step up from Swarovski military night vision items 20 years ago. Mega Drool => FLIR SYSTEMS, INC. Voyager II Long-Range Thermal Night Vision System at West Marine )
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Old 8th July 2011, 01:41 PM   #2380
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Hesener, i am aware of thermal differences in that design. 57° is a bit extreme of cause.
Our prototype stage had 1 Opamp quite hot. It is easy to simply exchange it. Fortunately the NE5534A is not that expensive. It will be interesting if the thermal differences affect
sound in any way.
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