My Thoery on the goofy GF-777Z AMP design

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Cpl-Chronic

Member (SA)
Heyya, all. :-P

I'm back with some more way-out crazy ideas about the GF-777Z. Poke holes in it, please. That's how I learn, by putting ideas out there to be tested.

SuperDuper pointed out that the Super-Woofer amps are fed by input signal that is bled from the output stage of the full-range AMPS for the outer speakers. This signal is 'padded' or resistor attenutated & inline with a capacitor to create a highpass shunt to roll off high frequencies from the super-woofer amp's inputs.

My question is why would SHARP create a speaker system based on efficiency over brute power & then devise a noisy signal path when you could split the signal from the pre-amp stage & control all 4 amps independantly & with less noise?

My theory, is the impedance relationship between the outer woofers & primary amp stage causes impedance dips & conversely current increases during low frequencies. If the outer speakers draw enough watts from the outer amps the 'Super-Woofer' amps will get a bass-boost of s few 'db'. The bassier the outer woofers get the more boost will be applied to the 'Super-woofers' because the impedance of the outer system affects the boost applied by the funky 'cascade' circuit. Why else would they ignore the standard split signal from the pre-amp?
 

Superduper

Moderator
Staff member
Wrong. But I am not going to waste my time explaining it to you, and then having you ask for proof.
 

tshorba

Member (SA)
Superduper said:
Wrong. But I am not going to waste my time explaining it to you, and then having you ask for proof.

Even when proof is provided he questions it and won't believe it, I'm with you :superduper: not much point in trying
 

Fatdog

Well-Known Member
Staff member
If I turn the bass to absolute minimum on the outer woofers, my Super Woofers are still boomin' with bass. ;-) It doesn't change if I add more bass to the outers.
 

Cpl-Chronic

Member (SA)
thank you FatDog for the input. As for the others, I won't waste my time with you & your little jabs as if you are so superior to everone else here on this site. I think it's YOUR egos that can't take a dissenting viewpoint & I admitted I was wrong about the amps but I KNOW I'm right about the horns. END OF STORY!!!

You're dismissed & learn some etiquette while you're at it too....

OH & while we're at it why don't I get some apologies about your assumptions that I PROVED to be WRONG!?!?!! HMMM? I'm waiting..... :nonono:
 

Cpl-Chronic

Member (SA)
http://www.enjoythemusic.com/magazine/m ... ingali.htm

And I quote:

"...Special Qualities Of Horns

What special qualities do horns have that endear them to enthusiasts besides having very high efficiencies? The horn may be viewed as an acoustic impedance transformer. When a diaphragm vibrates, pressure waves are created in front of it. This is the sound we hear. Coupling the motion of the diaphragm to the air is not an easy thing to do due to the very different densities of the vibrating diaphragm and air. This can be viewed as an impedance mismatch. We all know that sound travels better in high density materials than in low density materials, and in a speaker system, the diaphragm is the high density (high impedance) medium and air is the low density (low impedance) medium. The horn assists the solid-air impedance transformation by acting as an intermediate transition medium. In other words, it creates a higher acoustic impedance for the transducer to work into, thus allowing more power to be transferred to the air.

A horn is a tube whose cross-section increases exponentially. The narrow end is called the throat and the wide end is called the mouth. The transducer is placed at the throat. When the diaphragm moves near the throat, we have a high pressure with a small amplitude in a small area. As the pressure wave moves towards the mouth, the pressure decreases and the amplitude increases. Excellent natural efficient amplification.

As mentioned earlier, horns have very special properties, including lower distortion than conventional drivers, faster transient response than conventional drivers, and are easier to drive at high SPL's than conventional drivers.

Lower distortion at a given SPL: For an equivalent SPL, horns require a smaller diaphragm, and since distortion is directly proportional to the size of the diaphragm, a large diaphragm electromechanical transducer (conventional driver) has to move much more than a horned diaphragm in order to create the same SPL (sound pressure level). The larger the excursion, the worse the distortion. So, for a given SPL, a horn loaded system will generate much lower distortion than an electromechanical transducer.

Faster transient response: Since the diaphragm is smaller, it is lighter and thus it accelerates and decelerates faster. This, in the real world means superb, fast snappy transients. As the excursion of the diaphragm is very small as compared to an electromechanical transducer, the voice coil is much smaller and again, this translates to a lower moving mass and again, results in fast transients.

Higher SPL's with a given input wattage: Small voice coils also take full advantage of the flux in the pole piece gap. This increases the efficiency of the transducer allowing the amplifier to work with greater ease. Since the amplifier has more headroom and the driver handles peaks and high outputs more efficiently, horns are able to produce much higher SPL's before they distort.

Thus, in the normal operating range, horn designs are faster, more dynamic, have a better transient response, have less distortion, and are easier for an amplifier to drive than conventional driver designs.



Horns Have Impact!

You feel the music, you become part of the music, and the music becomes part of you. The full-range phase coherent wave front of horns produces a solid image and presentation, as opposed to the phase impaired, smeared, and diluted imaging of typical low efficiency conventional driver designs. Horns will never sound veiled or compressed. The performers will be there, in your room, performing for you in the same way and location as the original recording venue. If the performer was six feet from the microphone during the recording session, he will be six feet away from you when the performance is reproduced through your system, not fifteen feet behind the speakers. Why would one want the performers to be fifteen feet behind the speakers if that was not how the material was recorded? We want the performers to be in the same room we are in, in front of us, so that we can feel the music, front row center.

Due to their inherent benefits of low distortion, high efficiency, fast and accurate transient response, and wide dynamic range, horn loudspeakers provide a pure, un-adulterated musical presentation, a more organic and natural recreation of the acoustic event. As a result, each different musical selection is portrayed with its own character and life, not that of the playback medium......"


BAM!!!!

What else can I say? I'll find some stuff on driver coupling, so you can understand the poinjt about the 4 woofer design & you can't deny the 6db roll-off, before the amps, for the super-woofers is pretty decent with the right speakers & ahead of its time too. I heard a few opinons where the right speakers really bring out a nice sound in the triple-7 & i agree. Some said I wouldn't get much below 70Hz & I'm wasting my time with low efficiency subs but I PROVED them wrong with a 20Hz tone on normal settings, Voiume at '3'. It might not kill Conions but has good output that sounds more like a mini stage speaker than a ghetto-blaster & the sound carries farther forward because of the horns.

I LIKE IT!!!! :-D

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'FU@& THE H8-ers * It's about the knowledge' -- I know you guys love that catchy little slogan, eh? YO?
 

tshorba

Member (SA)
Cpl-Chronic said:
OH & while we'ere at it why don't I get some apologies about your assumptions that I PROVED to be WRONG!?!?!! HMMM? I'm waiting..... :nonono:

You are yet to provide proof of anything you have claimed, you demand proof from other to validate what you refuse to accept. By the way comparing a tweeter from its old capacitor (in crossover) to a new capacitor (in a totally new crossover) is not a fair comparison, the difference in the sound you hear could be attributed to simply recapping. Secondly you lowered the crossover point but say it is much better on highs, this disproves some of your assertions of your knowledge. Cans are headphones not speaker drivers, if you can't get simple terminology right why should anyone try and help or beleive your right?

Go back and read the thread, I never said horns don't work but myself and others questioned the design and your assumption for the reasoning behind why they were implemented.
 

Cpl-Chronic

Member (SA)
I just quoted a website thst explains the same aspects of horns I asserted earlier & the fact these horns are a hybrid type doesn't negate the qualities ALL horns share. The high-pressure zone in the neck of the horn is a natural acoustic amplifier & controls transients, increases SPL by a factor of 5 & the lens acts as a compression zone & the amount of refraction there will be negligable, just like a compression horn. Also, if you don't have any reference again for your denial of these facts, then your opinion is just that & it's verry egotistical to assume I have no knowledge that you can learn from. It's YOUR ego on the line, not mine & that is painfully clear to all, BUT YOU!!!

So, if you DON"T WNAT TO BOTHER debating the subject THEN WHY ARE YOU WASTING MY TIME & Y(OURS BY POSTING STUPID COMMNETS ABOUT ME instaed of debating the subject. If you think it's a waste of time, THEN SHUT UP!!! Stop posting useless jabs about me & hijacking this thread because your egos can't take a different view & challege about it.....

I admitted I was wrong about the amp circuits & you CAN understand how I copuld be mistaken, looking at bogus claims in manuals but if you don't back it up with something I can verify myself, then don't blame me for POLITLEY debating the subject. Once you chime in about how I won't listen & it's a waste of time to explain it to me then I will blast you for it because again, YOU NEED TO LEARN ETTIQUETTE & it's a waste of my time to debate horns with you when you clearly don't know what your talking about & your OPINION means nothing in the end.

I made a wrong asumption about how the amps are rated but that small point had nothing to do with the original thread & you knoow it. So far, I've proven my other points & no-one is aplogoizing for theior WRONG ASSUMPTIONS so go bother someone else about your BULLSHIT opinions about whether people listen to you or accept proof. I'm moving on....BUH-BYE!!!
 

Cpl-Chronic

Member (SA)
OK...moving on....The reason for my unorthodox theory about the amps setup is because some things don't jive about the assertion by SuperDuper & the statement FatDog made about the BASS having no effect on the super-woofers. He MAY be right but if FatDog can turn the BASS right down without the super-woofers changing in ouptut then that brings up more questions about the design, that's all.

If there is no purpose to the cascaded & dampened input to the 'Super-Woofer' amps then why go through the trouble of the unusual design instead of just splitting the signal from the PRE stage & feed both AMPS directly? I reject tthe notion that the engineers at SHARP just threw a design together as if they are a bunch of stupid guys who fell into the job. That's a stuid idea in its own right...

There has to be a design goal behind the circuit because it would be both CHEAPER, EASIER & provide a CLEANER signal to the amps by tapping the PRE stage for both amps & avoid clipping to the input circvuit of the second set of AMPS. LOGIC tells me there's some sort of BASS boost going on, that's all.

Now, if fatdog is correct & no change to the output occurs, when he turns the bass down then that flies in the face of what 'Super-Duper' asserted in another thread. IT'S IMPOSSIBLE to have both be true. If the outer amps are feeding the input to the inner amps than BASS adjustment would directly affect the super-woofers.

Now do you understand why I question these assumptions?

P.S. If you jump on my tem 'cascade' amp design, please know I'm using the term loosely & it isn't an invitation to lecture me on cascade amp designs as if it matters to this thread at all...stick to the subject & leave the accustations & jabs out of it......

FU@& the haters It's about the knowledge..... :nonono:
 

tshorba

Member (SA)
Ok cpl, please show me where I have said horns don't work, you will find it impossible because I never said that (as I said in my above post). Get your facts straight before having a go at me. You have a tendency to make assumptions and run with them.

You are stuck on the belief that people don't think horns work, that's your problem. It is not about someone having a different view, it is about you been unable to accept the truth and demanding proof from everyone, not believing it when given, and being unwilling to give any proof of your own assertions. To quote you after proof of the 10%THD was given past thread
Cpl-Chronic said:
My ears tell me a different story & I'm still trying to sort it out between what I see posted in various manuals, datasheets, websites, etc. & what my ears tell from past experiences, etc.

Now before you launch a tirade against me reread my past posts and you will see I never said horns don't work but you are unwilling to accept this because of your assumption that I did. I did make comments regarding the application and obvious flaws of the design.

If it was all about the knowledge as you say you would take on board other peoples input. Have you though about my comments about recapping the tweeters or are you going to avoid this because it doesn't suit your agenda to give an answer?
 

Cpl-Chronic

Member (SA)
I reject the idea the GF horns are for 'show' & don't work well & aren't efficient or similiar to compression horns. Those are assumptions on your part & NOT proven. I've submitted an article laying out the reasons why ALL horns, even these 1's will have very concrete benefits, sound louder, carry further, sound cleaner & handle transients better, compared to conventional tweeters.

If you look at the cross section of the GF horns you can see a very narrow neck that is somehwhat deep before it flares out. In fact, it's pretty close to a classic long-throw configuration designed to carry the high frequencies farther forward. The high pressure area of the neck is doing it's job, naturally & regarless of what type of lens & driver is used. That's why refraction won't matter as much. Picture the soundwave pressure 'pumping' through the lens & controlling the transient response of the cone making the signal response cleaner, louder & more 'musical'. YOU REFUSE to accept that you ARE wrong. You even challenged me by questioning why horns are so great if they aren't used too much in home audio while there's articles posted EVERYWHERE which overwhelmingly state that hrons are FAR SUPERIOR & almost every stage speaker & monitor is built using HORNS. WTF?!?!??!

As for the bickering about dust-caps, domes, wattage ratings & 'defensive tirades', you are the ones who went out of your way to refute my theories without addressing the subject of the thread or providing any reference for me to learn from.

Thanx again guys for raising the bar again...*sarcasm*

Driver coupling & the physics behind the phenomenon....
http://www.zainea.com/mutualcoupling.htm
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Fu#& the HATERS, it's about the knowledge... :nonono:
 

tshorba

Member (SA)
Cpl-Chronic said:
You even challenged me by questioning why horns are so great if they aren't used too much in home audio while there's articles posted EVERYWHERE which overwhelmingly state that hrons are FAR SUPERIOR & almost every stage speaker & monitor is built using HORNS. WTF?!?!??!

Read the thread again, the person who asked why they aren't used as much in home audio was Reli, not me. I am still waiting for proof that I have stated horns don't work.....
 

Cpl-Chronic

Member (SA)
tshorba said:
Cpl-Chronic said:
You even challenged me by questioning why horns are so great if they aren't used too much in home audio while there's articles posted EVERYWHERE which overwhelmingly state that hrons are FAR SUPERIOR & almost every stage speaker & monitor is built using HORNS. WTF?!?!??!

Read the thread again, the person who asked why they aren't used as much in home audio was Reli, not me. I am still waiting for proof that I have stated horns don't work.....

ok. it wasn't you that asked me that but it was you who went out of his way to make a snide REMARk on this thread so.......

Again, good JOB making this discussion personal & HIJACKING IT from the original issue!! It's so obvious.
 

Reli

Boomus Fidelis
Cpl-Chronic said:
YOU REFUSE to accept that you ARE wrong. You even challenged me by questioning why horns are so great if they aren't used too much in home audio while there's articles posted EVERYWHERE which overwhelmingly state that hrons are FAR SUPERIOR & almost every stage speaker & monitor is built using HORNS. WTF?!?!??!
Wrong according to who? You?

Face it, nobody except Sharp's engineers (who have probably died off) can "prove" that the GF777's horns are performing as optimally as you claim.

As I've said before, I really doubt that a mere $400 boombox with a product life cycle of only 1-2 years was designed using rigorous acoustic testing & re-testing.

Regarding my observation that MOST home audio speakers don't use horns......... If they are so great, why aren't they universal? And I am not talking cheapo Best Buy speakers either. I am taking $10-20K+ speaker sets. It strikes me as odd that most of them don't use horns, yet a cheap-crap $400-500 boombox would. That doesn't make me very trusting of your idea that Sharp spent a lot of effort designing those horns, and did it for audiophile reasons, rather than for styling and space efficiency reasons.

I guess one could speculate that the reason most home audio speakers don't have horns is because a living room or studio is not very big, and thus there is no need to project the treble very far, unlike a boombox sitting on a basketball court. But that is just speculation, until someone can "prove" that the Sharp's horns actually produce that desired effect. And hell, even if it WAS proven, it still wouldn't prove that THAT was the reason Sharp installed them.
 
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