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As I read the instructions whilst I built the IVY-III yester-day, I noticed that, in a chart, R32-R35 is listed as n/a. As I am using this with the Buffalo-II with 2vrms output, should I have populated R32-R35? I also seem to be lacking R13-16 (o no!) and am wondering if I can get away with not having them until they come, as they only affect gain (presumably, with them not populated, gain will be zero or infinite). I ask for reasons two: one, I want to listen to the DAC! and two, I've local head-fi meet on the fourteenth of August and I really want to have this project done by then. Other than these two things, wonderful packaging! A suspect that which was packed will sound even better than it looks.  |
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R32-R35 are not used for BUF-II
R13 - R16 are critical. So please double check that they were not misplaced.
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Russ White wrote:R32-R35 are not used for BUF-II Rats. I'll break out the wicker and excise the evil offenders! Russ White wrote:R13 - R16 are critical. So please double check that they were not misplaced. I thought so, but I figured I'd ask. I'm going to scour the area, but I would be shocked to find them: I would have had to either drop them AND fling them away, or open one of the bags, remove just these Rs and put the rest back. Grrr! I want my resistors! :'-( One last question: is there any merit to using better thermal compound? |
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Just got home. I will send out the missing resistors asap.
For thermal paste, basically, no. :)
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Brian, that's very nice of you indeed. Do you think that the resistors will make it by the fourteenth? I'd really like to have the DAC ready for the local head-fi meet.
As for the thermal paste, I'm surprised that you don't think that it would make a difference: I'd love to know your thoughts on this. Is it simply that the transistors don't dissipate enough heat to warrant the better stuff? |
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A bigger heatsink would do much more than the tiny improvement of a better thermal paste. Also, some if not most of the higher end pastes' have aging issues: they start out better than your normal paste, but in 1-2 years they degrade to a thermal resistance that's actually much worse than the normal paste.
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Quote:As for the thermal paste, I'm surprised that you don't think that it would make a difference: I'd love to know your thoughts on this. Is it simply that the transistors don't dissipate enough heat to warrant the better stuff? "Better" thermal paste might save you a few degrees C, but you likely won't be running anywhere near the danger zone for the Qs (150C). The thermal paste I ship with the kits was meant for CPUs, so it should be more than adequate for a couple transistors running around 50C. There is certainly no harm in trying other pastes; I just think your time and money are better spent elsewhere.
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LeonvB wrote:Also, some if not most of the higher end pastes have ageing issues: they start out better than your normal paste, but in 1-2 years they degrade to a thermal resistance that's actually much worse than the normal paste. Now this surprises me hugely: one would think that better pastes last longer than their cheaper counterparts. Is there a reason why this is not so? Brian Donegan wrote:There is certainly no harm in trying other pastes; I just think your time and money are better spent elsewhere. The paste is my room-mate's, so there's no extra money to be spent. Additionally, his comes in a syringe, which I expect will make the application easier. The sentiment is not unnoticed, though. Which reminds me -- is there a particular way in which I should apply the compound? Most sites dealing with this sort of thing are related to CPUs; the only transistor related site I could find recommended that I use my fingers (!) and apply the compound to a washer. Yes, I'm being excessive. Typical of me: I have what may just be the best DAC (  ) and I want to treat the accompanying parts as well as I can. |
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For application, you can use the edge of the plastic package as a wiper, or just use your finger. You want to be sure you have full coverage of the back of the transistor, but a very thin coat. Once clamped, you want the layer of thermal compound to be as thin as possible. The point is to avoid any air in the interface, and instead replace it with a thermally conductive medium.
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Quote:Is there a reason why this is not so? Yes there is: many of the high end pastes are meant for high end equipment (fi. in a PC: a high-end CPU, overclocked), and most of that equipment needs frequent replacement to remain up to date. So there's little need for it to work for a prolonged period of time. Instead the manufacturer focusses on the lowest possible thermal resistance for the short term.
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