Cpl-Chronic said:
Well, the sinks lack fins & the usual techniques for maximizing air contact but they are still pretty massive compared to most boomer amps, unless someone can point out a blaster with beefier sinks. I really haven't seen the guts of too many blasters but the M70 for sure puts out more watts with 1/2 the size sink & both M70 sinks are flat u shaped plates that are stuffed behind a woofer so almost no air circulation occurs.
Once again, you take a stand and insists that it's true unless someone else "proves" to you that it's not. Tshorba just showed you an example. There are many more examples like that with boomboxes using large finned heatsinks. You said yourself that you haven't seen the guts of many boomers. We are telling you that there is nothing special about the GF-777 heatsinks. That is a common and inefficient design.
As for the M70, you need to understand a couple things. First, the M70 uses a completely different amp setup. Like the GF-777, it has 4 amplifiers but those 4 amplifiers powers only 2 speakers as each pair of amps powers only 1 channel (they are operating in bridged mode) and produce 7wpc (RMS) quite effortlessly (through 8-ohms). In contrast, the GF-777 pushes their 4 hitachi-amps (weaker than the 4 panasonic amps used in the JVC's imho) to power 4 speakers. Secondly, the M70 heatsinks are black and if you'll do some research, you will find that black sinks transfers heat better than plain silver sinks, and finally, unlike the 777 which made absolutely no effort to properly orient the sinks for reasons of convection, the M70 heatsinks are properly oriented in the vertical position and the U-shaped channel acts like a chimney that will draw cold air through and across the plates as heat rises. Anyone who's ever lit a match in a fireplace understands the chimney effect as the lit match instantly draws air up and resulting flow develops. The 777 sinks with the horizontal plates actual block, impede and trap heat in the pocket. It would take lots of lab time and proper instruments to determine which is actually more efficient but I would not be suprised one bit if the M70 heatsinks do a far better job at eliminating heat than the GF-777. In fact, if you look at the back of most M70's you will find a large amount of dust on the rear ventilation slats which suggests that the M70 design is quite efficient in pumping air through the chassis via simple convection. JVC did it right and took the time and effort to engineer a proper heatsink large enough for the application, coated for efficient heat tranfer, oriented to promote air flow rather than impede, and channeled to further charge the air flow.
Tshorba's amp is one example but on boomboxes (or all amps in general) where cooling is taken seriously, the cooling fins/slats are almost always vertical to properly channel air flow as the natural flow for heat is to rise. In fact, if you were to purchase a heatsink from companies such as thermalloy, their products always have product datasheets that show thermal resistance values given and the specs depend upon whether natural convection or fan cooling is employed and even the installed orientation will make a difference. You'll also find many will be black anodized for maximum heat transfer efficiency.
The point here is to make you aware that (1) there is far more to heatsink design and implementation than you know and (2) there is nothing special about the GF-777 heatsinks which really while they look impressive, does not suggest prowess of any remarkable nature. In fact, that design is quite cheap/common and lacks engineering time/effort to maximize efficiency.
Man, some JBL woofers in a 777? 
