My GF-777Z ** Project PHAT-AZZZ BASS!!

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Cpl-Chronic

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My various mods for my GF-777Z, displayed in photos:

This is a work in progress & will be incomplete, at various points in progression.

This is the finished woofer replacement as viewed from the rear of the interior. The outer woofers have large magnets that actually dwarf the basket it's attached to. With 91db 1W/1M, you would hope so. If you look closely, you can see the transformer wedged to the side of the box between the to outer drivers(woofer/tweeter) The trick is you can't fit these in the GF without major surgery & relocation of the transformer. I'll talk more about that later.


As you can tell by the magnet size & quality of the build, these Subs & Mid-Bass drivers are not f$@%ing around. the Black center mounted woofers are 4-OHM subwoofers with an FS 0f 38Hz in 0.16 cubic foot enclosure. They really pound. The outers are 2 ESS Center channel Woofers that are perfect for mid-bass & low-Mid output & 91db - 1w/1m.


Here's a shot of the car audio cross-overs I bought to filter the high/lows. The old wiring overlapped the outer woofers with the tweeters & used a simple Capacitor crossover for the tweeters. This is why the treble was muddy. These are car audio crossovers & the cross-point is 3K @ 4-OHMS for woofer & tweeter. PERFECT!!!


Now, I have to find some tweeters that will work with the horn apertures of the case. I was lucky to have these tiny little speakers I bought on eBay a couple of years ago. They're poop but the Infinity car tweeters are 4-OHM & a physical match to the old cone drivers.


Here's the old & new tweeter for comparison. Notice the much larger magnet & the cone is made of waterproof polymers & they sound much better too. I had to line them up & drill holes so they would mount properly.


If you look at the next 2 photos, you can see the original tweeter & the new tweeter loaded into the plastic lens of the horn. Notice how the dome of the new tweeter matches the aperture more closely than the original. I had enormous luck that the shitty speakers in my basement would be such a great donor for my tweeter replacements.




This photo shows the new tweeter mounted to the horn.


The transformer was removed & the plastic bracket of the case was trimmed to allow the woofer to fit. The huge magnet on the back was interfering with the original placement of the transformer. Now, it's time to find another spot for it.
 

Cpl-Chronic

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Fatdog said:
Now... let's hear it! :thumbsup:

Heyya Fatdog....still working on it. Once I get the rattles out & the back sealed, I'll post a video of some fat beats. Maybe I can get a digital recorder & a couple of mics to give it real treatment. The crossovers work great & the center woofers really thump but the cancellation from the vented back really robs it of bass. That's why, no-one ahs been successful yet of getting the lows out beyond a foot away from the mighty GF-777Z...will post more pics tonight... :thumbsup:

In the meantime, here's a little teaser to give you an idea how it sounds right now with the new mid-woofers added:

!!!WARNING!!! Turn your computer speakers down before watching:

GF-777Z_SNARL!!!

!!!WARNING!!! Turn your computer speakers down before watching:
 

Cpl-Chronic

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:thumbsup: Some more pics I'm doing some listening tests right now & the bottom octave, below 50Hz is gone but the woofers are damped sufficiently & provide some powerful & punchy midbass. It has a hard time with 20-40Hz range because the woofers are really moving & distorting in such a small box. I hope dead-mat & more insulation around the subs will work better. I'll post a video soon to give an idea in sound quality.

SEALED BACK for better bass response



35-New woofer & subwoofer. I think they look sharp together & understated

Direct Link: http://i48.tinypic.com/244y7ts.jpg

36-Front view of new woofers, loaded

Direct Link: http://i50.tinypic.com/6rukhk.jpg

Transformer in new location.
Notice the 2 white plugs that are sticking out. They are home made so that the transformer can be disconnected from the circuit board that is on the back panel. They are snipped from an old computer connectors I scalped from defunct equipment.

Direct Link: http://i49.tinypic.com/1538ls3.jpg

38-Back Panel power board with home-made Transformer connectors

Direct Link: http://i48.tinypic.com/x6let5.jpg
 

Jboogie2384

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Uuummm, I don't wanna be a party pooper or anything but if you seal up the back how would the amps keep cool trying to produce this bass your expecting from it? Love the look of those grey woofers by the way!
 

Cpl-Chronic

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Jboogie2384 said:
Uuummm, I don't wanna be a party pooper or anything but if you seal up the back how would the amps keep cool trying to produce this bass your expecting from it? Love the look of those grey woofers by the way!

EDIT: I have to add the JBoogie is right to bring up concearns about modding & especially when comes to ventilation & power circuit MODS. What I'm doing is dangerous & shouldn't be tried at home. I do risk unintended consequences if I make any mistakes. *fingers crossed*

You make an interesting point JB but I tihink it'll be OK. The power transistors are bolted to heavy heatsinks & unless I'm out in 120 degree weather, it won't reach critical temps at all. I'll have to take it out for a test as we are reaching 110 degrees on some days. I'll let you know how it does in those conditions but inside my air conditioned house, it's been working fine so far. The transformer is oversized too & runs relatively cool as well which I give credit to SHARP for the quality of the build & expect the AMPS to be pretty solid too. It's probably why these things have survived so long. If I find the power fading from heat, I might rig up a 15v fan to cool the heatsinks & move some air around. It would be easy to wire it up from the power circuit & put a switch in to turn on/off.
 

Cpl-Chronic

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I improved the insulation & finished it for the rear panel. The center woofers are better behaved after the added insulation on the back panel. Overall the sound is better & strong low/mid bass but the sub-woofer octaves below 50Hz are missing. I believe this is where the depth of the plastic cabinet is a limiting factor & the bottom 2 octaves(10-40Hz) is hard to control without a sealed back & plenty of prudent insulation. I'm hoping to get the woofers pumping at 60-120Hz, clean. If I can, those 8watts x2 RMS will pump it out pretty good. I have to wait 'til tomorrow afternoon to test her out thoroughly but in the meantime, some pics will be up soon showing the insulation spots, in case you want to deaden your box more. It really works if you use good acoustic insulation.

MORE PICS COMING SOON...
 

blu_fuz

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Cpl-Chronic said:
!!!WARNING!!! -- TURN YOUR SPEAKERS DOWN BEFORE PLAYING THESE VIDEOS OF THE GF-TRIPLE 7-zee. THESE VIDEOS ARE LOUD & HAVE A LOT OF BASS ENERGY & NOISE!!! Again, this is my crappy camera so you know it sounds cleaner in person. Still, the midbass comes through pretty strong & you get the idea.

Reggae DUB

HASHIM BALLS

Play at your own risk


Nice smoke screen in the HASHIM BALLS link - wonder why you were coughing :hmmm: :blink: :jawdrop: :pimp:


You need better lighting for these vids, I want to see the speakers MOVE :breakdance:
 

Cpl-Chronic

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blu_fuz said:
Nice smoke screen in the HASHIM BALLS link - wonder why you were coughing :hmmm: :blink: :jawdrop: :pimp:

You need better lighting for these vids, I want to see the speakers MOVE :breakdance:
Yeah, I'm goint to work on that & post 1 or 2 more vids later tonight...So far, I'm pretty happy with the way the mods turned out. :afro:
 

Reli

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Good job so far, but how about using Dynamat? Seems like that would be the best way of sealing the bass.
And those tweeter horns seem like they block way too much of the tweeter. I think that was a dumb idea on Sharp's part.
 

Cpl-Chronic

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Reli said:
Good job so far, but how about using Dynamat? Seems like that would be the best way of sealing the bass.
And those tweeter horns seem like they block way too much of the tweeter. I think that was a dumb idea on Sharp's part.
Good idea Reli & already done. I dead-matted the interior before isnulating it & have to get more for the rear panel. It really pounds now. As far as the horns, the center dome of the tweeter fits the horn aperture perfectly & it actually sounds quite balanced & natural for a cone tweeter so I would disagree with you about the preactical aspects of a horn loaded tweeter. You may not know but a horn laoded driver is way more efficient than the bare tweeter mounted to a panel. That's why the old victrolas had that rediculously large horn coupled to the record needle. This acted as a natural amplifier as those old Victrolas used no electricity.
 

Reli

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But the sound from a tweeter (or any speaker, for that matter) comes from across its entire diameter......not just from the center cap region. So if the opening in that horn is only big enough to show the tweeter's center cap, then it's only getting part of the sound. The rest gets trapped inside the boombox. In my unscientific opinion of course.
 

tshorba

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Cpl-Chronic said:
Reli said:
Good job so far, but how about using Dynamat? Seems like that would be the best way of sealing the bass.
And those tweeter horns seem like they block way too much of the tweeter. I think that was a dumb idea on Sharp's part.
As far as the horns, the center dome of the tweeter fits the horn aperture perfectly & it actually sounds quite balanced & natural for a cone tweeter so I would disagree with you about the preactical aspects of a horn loaded tweeter. You may not know but a horn laoded driver is way more efficient than the bare tweeter mounted to a panel. That's why the old victrolas had that rediculously large horn coupled to the record needle. This acted as a natural amplifier as those old Victrolas used no electricity.
The aperture of the horn throat should match the driver, when this is the case the horn loaded driver is more efficient than a standard driver. The way sharp has done the mount/aperture creates a lot of refraction behind the plate due to the larger cone.

The sound is not lost inside the box, but the air space in front of the tweeter is forced through the aperture like a port in a bass reflex design
 

Cpl-Chronic

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tshorba said:
The aperture of the horn throat should match the driver, when this is the case the horn loaded driver is more efficient than a standard driver. The way sharp has done the mount/aperture creates a lot of refraction behind the plate due to the larger cone.

The sound is not lost inside the box, but the air space in front of the tweeter is forced through the aperture like a port in a bass reflex design
Well, you are right that a professional horn has a driver designed to fit the aperture more closely & the entire diaphram is coupled to the lens of the horn in a traditional design while the SHARP horns are more of a hybrid horn using a cone tweeter. Having said that, for a ghetto-blaster, the GF's horns use a workable trade-off that uses the energy of the tweeter's domes where the higher frequencies emanate anyway & amplify them with a horn aperture like the victrola example I used earlier. In effect, they are damping the mid-range frequencies, say between 1-4KHz & boosting the high frequencies from the dome region of the tweeter & it works quite well & sounds very balanced considering it's D-CELL audio anyway. I definitely hear a lot of high freuency energy from the infinity tweeters I loaded & the domes match the lens aperture perfectly. I bet if you pull the tweeters off the horns & listen to them naked, they'll sound flat with too much mid vs treble...
 

Reli

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tshorba said:
The sound is not lost inside the box, but the air space in front of the tweeter is forced through the aperture like a port in a bass reflex design
You are right, I didn't look at it closely enough.
 

Fatdog

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TheSaltineCracka said:
whats the differance between the GF - 777 and the Gf - 777Z?
They are basically the same. The GF-777 boomboxes all have letter suffixes (e.g. Z, H, E, etc.). It's just a generic way to reference them.
 

Cpl-Chronic

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OK FatDog...The moment has arrived for the MOD v2 with a little luantiics thrown in. You guys wanna see woofers bouncing & decent BASS. Watch the video in full sreen to see them bounce. Don't forget, this is D-CELL audiio but I think it''s improved from it's original form. Anyway, let me know if you can hear any difference at all in the lows/highs. everyone tells me the GF is sexy & feature packed but the sound SUC#S BA!_!_S..Anyway, here's a clip of the woofers really being driven by a bassy track....

More Bounce to the ounce

Notice that the sound is pretty balanced between the 3 drivers(BASS/MID/TWEETER) & it isn't grossly distorted although a bit noisy on my camera. The subs I put in probably dip dow to 2-OHMS with low frequencies & I can over-drive these woofers @ 30-50Hz....It's insane!! This box has mroe acoustic power than it can contain without rattling apart on some tracks. I'm not making this s^!# up. I still have to dead-mat the back panel & that should damp it further like a car panel does. Sealing the back & insualting corners & panels DEFINITELY improved woofer control & overall SPL output but the 30-50Hz range is a bit muted but finally, it is there This gives a nice bassy reggae feel with cleaner highs from the infinity tweeters. Overaall the mid-bass speakers melted right in between the 'SuperWoofer'(s) & The insulation works wonders but you have to use the good acoustic stuff they use on the inside of tower speakers & studio monitors, etc.
 
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