Heyya all. =)
This is kind of a long post so I apologize if you already know about coupling:
I'm all geeked over my first super-blaster. The GF-777Z. I've realized 1 thing about this blaster that no-one seems to touch upon. It's glory is unrealized in its original form. The 4 woofer, 4 amp design has real advantages over the more traditional large 2 woofer approach & takes advantage of the the acoustic law of driver coupling. For every watt of power applied, 2 identical drivers add a 3db boost in SPL over a single driver.
For example, 2 woofers @ 15w each will be 3db louder than 1 woofer @ 30w. Now, remember that doubling the amlifier power of any speaker only yeilds a 3db increase in SPL. Therefore, 2 woofers have the SAME SPL as doubling the amp output on a single woofer. A 10db increase in acoustic output roughly corresponds to a doubling of 'volume' to the listener, on average & requries 8 times the amplifier power. If you use 4 woofers, the acoustical power output is 6db higher, over a single woofer, for every watt of amplifier power.
Now, all 4 woofers in the GF-777Z are simple paper cones with treated & untreated edges & a 4w rating. Add to that, 4 amps that EACH put out 8w RMS into a 4 ohm load @ probably 0.5% THD rating. Peak to peak which is probably what the '8w max.' speaker rating is. If I'm wrong feel free to post here & let me know where my guess is off.
Well, I figured, if I find some good, high efficiency woofers, with a high SPL rating, I might make this thing into a high-octane performer. I know the crap speakers are holding this thing back but the right set of fast accurate woofers would bring this thing into its own. What do you think?
Crazy or Crafty?
This is kind of a long post so I apologize if you already know about coupling:
I'm all geeked over my first super-blaster. The GF-777Z. I've realized 1 thing about this blaster that no-one seems to touch upon. It's glory is unrealized in its original form. The 4 woofer, 4 amp design has real advantages over the more traditional large 2 woofer approach & takes advantage of the the acoustic law of driver coupling. For every watt of power applied, 2 identical drivers add a 3db boost in SPL over a single driver.
For example, 2 woofers @ 15w each will be 3db louder than 1 woofer @ 30w. Now, remember that doubling the amlifier power of any speaker only yeilds a 3db increase in SPL. Therefore, 2 woofers have the SAME SPL as doubling the amp output on a single woofer. A 10db increase in acoustic output roughly corresponds to a doubling of 'volume' to the listener, on average & requries 8 times the amplifier power. If you use 4 woofers, the acoustical power output is 6db higher, over a single woofer, for every watt of amplifier power.
Now, all 4 woofers in the GF-777Z are simple paper cones with treated & untreated edges & a 4w rating. Add to that, 4 amps that EACH put out 8w RMS into a 4 ohm load @ probably 0.5% THD rating. Peak to peak which is probably what the '8w max.' speaker rating is. If I'm wrong feel free to post here & let me know where my guess is off.
Well, I figured, if I find some good, high efficiency woofers, with a high SPL rating, I might make this thing into a high-octane performer. I know the crap speakers are holding this thing back but the right set of fast accurate woofers would bring this thing into its own. What do you think?
Crazy or Crafty?
But it sounded convincing. "I'll buy that for a dollar" 
with Cpl. I swapped mine out and it pounds like all hell broke lose. The original speakers do hold it back from its full potential. Save the old speakers tho. Some old folks like originality so if you plan on selling the 777z down the line then keep them or sell them to somebody in need of the originals.
Well, so far am pleased with the sound. It's close to balanced. I'm using the original inner super woofers as the outer speakers & they work quite well witht he new horn tweeters. Upper mids are still a bit muted but that should smooth out with the ESS 6.5's I ordered. I'm hoping the new outer woofers will make the mids a little clearer & warmer while boosting the 40-80Hz band...which is perfect for kick-drums & bass guitars. Plus, a light woofer with a foam surround is what I need for the rich mids to mate with the horn. Reggae sounds awesome so far & even rock & roll isn't tinny anymore. 
Keeping the horns was an improtant goal as horn laoded tweeters are 5 times more efficient than a naked dome or cone tweeter & the sharp GF horns are a decent design. The new sub-woofers were not very expensive but are decent quality & roll off at 40hz in a small sealed box(0.16 cu feet). They really 'pound' & the box rattles my bookshelf now. 
