My 2nd GF-777Z ** PROJECT M70 SIZZLE

[THAFUZZ]

The SHARP 777Z horn design is an exercise in trade-offs. The horns use a hybrid horn lens similar to the M70 horns that acoustically amplifies the center dome energy which creates an extended frequency range, while damping midrange & lower midrange frequencies.

It's hard to explain but horns are much more efficient than open faced tweeters & that makes up for the fact that the tweeters are partly covered & blocked out by the narrow horn neck. Only the dome is visible from the mouth of the horn & therefore the primary emitting surface that couples acoustically to the horn. It is inefficient, compared to a properly designed compression horn but the freq response curve for the entire horn is boosted in the treble range vs the same tweeter in a traditional open face mounting at the expense of mid & low mid ranges.

Most people don't realize the 777Z was designed to fill a room with sound, not hang off your shoulder or sit on your picnic table...If I stand about 5-10 feet back from it, the horns come alive but standing next to it, the horns sound subdued because of their narrow vertical axis & wide horizontal axis. They were meant to throw the high frequencies farther forward than traditional open faced tweeters...

That is the best I can explain it ....


Brace yourselves,

The long protracted 'Is this a horn?' debate is coming.....

Thank You

 

[Beosystem10]

Those aren't horns, technically they're bell ends. The horn is the entire structure from the root to the bell end.

 

[Cpl-Chronic]

Trust me, yes it is a horn. I studied basic waveguide & horn theory. It has a narrow neck opening to couple the tweeter's energy to the denser air in the neck of the horn. As the air travels out of the wide mouth of the horn, it's velocity increases & therefore increases acoustic output. Thus, you have acoustic amplification. Google horn theory & educate yourself. The design of the sharp horns follows a classic long throw design that carries the soundwaves farther forward than traditional tweeters. It uses a hyrbrid lens to couple the tweeter's center dome energy to the horn's neck & out the 'BELL' or ,MOUTH' of the horn.

If you look at the inside of the SHARP 777Z horns you can see the domes of the tweeters peeking through the neck of the horns. They actually perform the same task as traditional compression horns but with a trade-off between efficiency & the boosted frequency response of the entire transducer, as a whole.

The 'BELL' or horn becomes an extension of the tweeter's emitting surface.

http://www.sonic-horns.com/sonic_horn_shape.htm

http://en.wikipedia.org/wiki/Horn_(acoustic)

 

[Beosystem10]

Finish the course then I'll budge.

 

[Cpl-Chronic]

https://www.grc.com/acoustics/an-introduction-to-horn-theory.pdf

 

[Beosystem10]

Yes, as I already said, the horn is the entire structure from source (AKA root) to bell end so we're agreed apparently.

 

[Northerner]

Bell end...chuckle chuckle :-0

 

[Beosystem10]

Bell end...chuckle chuckle :-0

Seriously Si, that's what it's called.

 

[Cpl-Chronic]

@Beosystem10:

Yeah, I think we are talking about the same concepts here but our terminology is different. Yes, I am talking about the entire horn, including the 'emitter' or in this case, the tweeter, the 'lens' or 'housing' for the emitter that mounts to the neck, the 'neck' or 'throat' & lastly the 'bell' or wide end of the horn. In its entirety, it is a working horn in every sense of the word.

Some have mistakenly claimed that the sharp 777 horns are NOT really horns, fake, only for looks, etc. That is simply not true.

Cheers,
Cpl

 

[Beosystem10]

Quite so.

 

[riker1068]

 

[Line Out]

The Philips D8634 and D8623 also have horns, the emitter is just a piezo plate. The D8623 has just a plain round horn, as the D8634 has eight "plates" inside of the horn. Don't know if they are there to control dispersion or just for looks. Been thinking of replacing the piezos with small car dome tweeters.

Some Sharps (for example GF-8686H) have very little piezos with "horns" but those are miniature and I don't know if they coul be called horns. In any case, they also have much higher sensitivity than just plain plates.

 

[Cpl-Chronic]

Well, to continue the discussion, yes, horns are a special kind of 'Wave-Guide' & vise versa. so to speak. Even a shallow wave guide will boost acoustic output by a few db's for the same amount of electrical power input to the driver. A well designed horn can boost acoustic output by a magnitude of 5(+15db) versus a front loaded flat face cabinet. The basic concept is akin to a venturi forcing air into a high pressure zone & then opens up to increase air velocity. As the air travels from the small end to the large end of the horn, guide, etc. the air increases in velocity at the mouth end of the bell, increasing acoustic ouptput & reducing transient nosie. Even the small conical horns/wave-guide of the Philips units you mentioned do boost acoustic output & reduce noise from the piezos.


The same is true of the inset center woofers of the Sharp 777. The shallow wave-guides of each center woofer acts to boost output & diminish transient noise. That is why on low volume, the 777 has a very stage speaker type of punchiness you do not get from other blasters.

It has a very precise bass sound on low \volumes for that reason & sounds more like a bass head than a Warm Lasonic Hi-Fi type of bass....

Cpl

 

[riker1068]

I like the 777 and look forward to getting dome more of them

 

[riker1068]

Are those center woofer the bose 2ohm? Did you change or add dust caps? Mine has the wires showing in the face of the woofer. Can I just cover the original dust cap with another say... 3 inch dust cap? I hope to try to play with mine on Saturday.

 

[Cpl-Chronic]

Never tried new caps so don't know how that would affect sound. The visible leads never bothered me personally. I was more interested in sound improvement over asthetics of the woofers....& price too.

Cpl

 

[riker1068]

I like your response. Sound is more important. Price helps as well. How ya liking the 6400 ?

 

[Cpl-Chronic]

Are those center woofer the bose 2ohm? Did you change or add dust caps? Mine has the wires showing in the face of the woofer. Can I just cover the original dust cap with another say... 3 inch dust cap? I hope to try to play with mine on Saturday.

Yes, all 4 woofers have a DC resistance of 2 OHMS & is probably in the realm of 2.3-2.5 OHMS nominal impedance....