did you see that the mains xformer is potted with small steel band around it and some bathroom glue...
Yes, and that is why my PSU is going to be in a seperate box a meter or so away from the amplifier...
I have not responded to your email, because I am focusing on getting it done. I have the kits packed.About 8 people will ship today. THe others, who ordered the Matched fets are having to wait a couple of days because I ordered .1r resistors for everyone, not cnosidering that the IRF parts will need .47r. That means they will ship(yours included) when I get them.
FirstWatt Packaging Thermal Characteristics
I have been studying the FirstWatt enclosure and the way boards attach to the heatsinks, which I find to be very appealing:
The question is how much the flanges impede heatflow to the main heatsinks.
I have been studying the FirstWatt enclosure and the way boards attach to the heatsinks, which I find to be very appealing:
- The boards attach to 90-degree aluminum flanges that allow the boards to mount perpendicular to the heatsink.
- The boards mount underneath the flanges, allowing circuit traces to run on both sides of the output FETs.
The question is how much the flanges impede heatflow to the main heatsinks.
Essentially none -- the flange is on the interior face of the 'sink, where little heat is dissipated. The outside of the heatsinks is where all the heat goes.
I was also thinking some month ago, when I had my J2 crisis hearing an original and my clone in contrast, both having the same THD and spectra, if the heatsinks are more important than I thought.....
My thoughts, get the the SS quicker their final temperature only warming up the flange at the beginning with Nelson's heatsinks? Is too much heatsink bad for the sound? Mine got only 45 C degrees, Nelson's 55 C
Not to speak from the Semisouth case itself, it got very hot in Nelson's arrangement, around 75 C.
Is this bigger heat an advantage for the sound?
I even reduced my heatsinks to get a similar heat at the SS, but my results were not definite.
My thoughts, get the the SS quicker their final temperature only warming up the flange at the beginning with Nelson's heatsinks? Is too much heatsink bad for the sound? Mine got only 45 C degrees, Nelson's 55 C
Not to speak from the Semisouth case itself, it got very hot in Nelson's arrangement, around 75 C.
Is this bigger heat an advantage for the sound?
I even reduced my heatsinks to get a similar heat at the SS, but my results were not definite.
Dunno know about the idea, but normally more heat would mean more Yfs.. But in this case, it would appear that this part would not fall under that norm. Isn't this one of the reasons we can get away with no source resistor. No need to protect from thermal runway as bias decreases with increasing temp.
Ilquam,
Check out Conrad's site. They have a write up about this very thing, as they have flanges on their sinks.
Here ya go
http://www.conradheatsinks.com/technical-details.html
Check out Conrad's site. They have a write up about this very thing, as they have flanges on their sinks.
Here ya go
http://www.conradheatsinks.com/technical-details.html
Last edited:
Thermal runaway is a somewhat separate issue from heasink characteristics. Depending on the particular MOSFET, the datasheet will specify a maximum junction temperature and thermal resistance from the substrate to the MOSFET package. Depending on the mounting technique (mica and grease, therafoil, ...) an additional thermal resistance exists from the package to the heatsink. Combining the heatsink geometric/thermal model, air temperature, airflow, and MOSFET power dissipation, one can estimate the junction tempereature.
I was addressing Generg's statement about how the remp of the device might affect performance and ultimately sound. It is interesting to consider that in Nelson's big amps, the fets are biased low, but total temp is high, due to accumulated heat of all the fets. Perhaps this is a way to increase gain/yfs without raising rail voltage.
I don't think you wany a flange that's bolted on. You can see on the Conrad page the performance suffers. Horizontal fins aren't good either.
I agree that an integrated flange like Conrad provides is best, but would ArticSilver or a similar thermal adhesive do good enough for attaching a flange?
I don't think so. You could try it maybe with a much larger surface attached to the heatsink. However, I still don't think it will be as good as a one piece design.
The Conrad WMF30-1F-75 appears to be appropriate for the 60-70 Watts per channel needed for the F5, F6 and other 25W/ch amplifiers. It is very long at 300mm. I much prefer to form factor of the HeatsinkUSA 10.8 heatsinkhttp://www.heatsinkusa.com/10-080/. Unfortunately it does not have the flange.
I know there have been a couple attempts at GB for the sinks. Major pain though and extremely expensive otherwise due to shipping. Rigt now, the store chassis or Heatsink USA are the best options. For my next big amp, I was going to mount 8"x3/8x20" plate to two HUSA 10.08 profiles, but have to have them machined flat to do so, so I am looking for alternatives. Can't say that I care about flange that much ask prefer directly ting to plate. EUVL used flat back version in his F5X, if that tells you something about comparison.
