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In the Forum: Horn-Loaded Speakers
In the Thread: Eventually - a reasonable midbass horn from GOTO
Post Subject: A compression driver as a musical instrument.Posted by Romy the Cat on: 2/10/2008
 Johan Dreyer wrote: |
| I had a SG370 mid apart only yesterday.I should have taken a photograph. I have also seen the inside of the tweeter. They are very similar, so I have no reason to suppose the low mid SG 505 will be much different. I'll try to explain. I think they are in basic structure close to the WW 555. |
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Hm, this is infesting. The last person who was trying to spin Goto drivers to me was assuring me that Goto drivers are absolutely dissimilar to 555 drivers. I did express doubts at that time but I had no facts… What you say is very interesting and if you have pictures then it would be fun to see them. | Johan Dreyer wrote: |
| A few observations.The dome on the mid is about 4cm diameter and very beautifully made.It is obviously very thin and delicate compared to the JBL.It has no metal surround but is bonded to a FEP film that is glued to the flat surface surrounding the phase plug.This film is surprisingly big and really very thin and covers a big area. According to Goto this is one of the secrets as conventional compression drivers resonate in the surround (cf the different resonance patterns -frequency response in the otherwise identical JBL 2440 and 2441). |
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Yep, it is my observation as well. A heart of any compression driver is a diaphragm and it’s suspension. A compression driver is very similar to brass instrument where diaphragm is the musician’s lips producing different pitches, overtones and harmonics. The difference is that brass instruments do “a tone by time” injecting the standing wave into the belly of an instilment but the compression divers produce new tones by constantly change the virtual lip’s embouchure. So, the diaphragm and it’s suspension could not be good or bad but they rather have a metaphysical value that could be assessed in context of “everything else”. It is absolutely imposable, at least to me, to look juts at the diaphragm and to say what it is and how it will sound. | Johan Dreyer wrote: |
| All in all it appears exceptionally simple ,but exquisitely engineered.I have no idea how that membrane can be accurately glued-certainly not a field job!.There are no guiding pins,but 2 dimples in the front magnet face where the terminal screws go. I suspect that these may act as alignment guides as the front screws are tightened to match up.I opened mine because I thought it was scraping.The scrape seems to have originated from the front screws working slightly loose durng shipping-gentle tigtening immediatel solved this. |
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You have to be very careful with it. It is remotely possible that the driver has no alignment mechanism and centered by gluing of the VC. This method of diaphragm setting has own plusses and minuses. About your scraping sound – the compression drivers should be cleaned once in a while and they might pick some dirt from air. It is normal.
| Johan Dreyer wrote: |
| I was very disappointed in your tweeter battles that you never tried a Goto tweeter.Like you I really loved the Celestion SL6/600 tweeter's tone,but ultimately found them a bit slow.The Gotos I feel has that tone,but also speed and of course efficiency.All in all I think the best highs for me- I come from a tradition of "British "sound so you may not relate,but I think you will. |
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I am not disappointed in my tweeter battle. It is a different thread, if you wish I will be happy to explain my view on the subject. I did not tried Goto tweeters though in my system.
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