[SET Man]

Hey!

    Lastnight I got around to do some dusting off my system a bit. Than I tighten those screws that hold my Fostex 167E to my crappy looking cabs Man! I had to do a almost 2 turns for each screws. Amazing how screws got loosen over time.

    While blowing off dust on my speaker drivers something came into my mind. Hmmm... I remembered that I've read somewhere that grounding the chassis of speaker driver improve the sound.

Tonight after listing to my system for a while... just want to make sure if tighten up those screws have any affect on sound. Well, I can't tell. So...



Off to grounding the Fostex chassis! I'm too lazy to take them out of the cabs and solder the wire to the chassis. So, I came up with a better solution. Using gounding lug. I unscrew one screw, using exacto knife to scrap off some paint around the screw hole than put the screw back with the grounding lug. Now I could use alergator clip to make the connection on the super horn tweeter posts. The other plus side with tis is that I could change the polarity and do disconnect it on the fly for comparison

Okay, so does it work? So, far I could say that yes it does work! I could hear some change in the sound. The sound seem to have better focus, image more solid and overall with less glare.... quieter?  Oh! and the bass seem tighter too. Oh! by the way I ended up connecting it to the negative side.

It had been only a few hours with this. But so far I think I like the improvement. I guess I will just have to leave the clip on... well I'm just too lazy to open them up.

This is nothing new. I'm sure some of the DIYer and some speaker manufaturers already know about this. So for those with Fostex driver I do reccomend you give this a try.... yes those Omega and Horn Shoppe people if haven't done so already.

If you do thise please let me know if you hear and like or dislike the improvment.

Well, back to enjoying my music a few more minute before I go to bed.

Take care,
Buddy

[kfr01]

I'm curious. 

What's the theory behind this?  Any links you have would be greatly appreciated. 

[SET Man]

I'm curious. 

What's the theory behind this?  Any links you have would be greatly appreciated. 

  Hey!

    Well, I'm listening to my system right now and again I did some comparison between grounded and not grounded. And I am now could 100% say that I'm not crazy, it does changed the sound in a good way.... at least for me

   As for the info and link about this? Well, I don't have it. This came up when I was doing researchs on Single Driver speaker back in 2001 to early 2002 to build my own pair. I did not pay much attention to it since my priority back then was to get the project going and tweaking would come in later. But somehow this stick in my head after all these years and it just came out from the backof  my head a few night back.

  Anyway, as for the theory behind this. I have to admit that I'm not totally sure about it. But I think this have to do with the driver's voic coil responding to the grounded speaker chassis. Maybe this give a better control of magnet field? Or with grounded chassis just like grounding amp chassis this helps blocking out the RFI and EMI getting to the voic coil?

   Anyone want to try this and let me know just to confirm my own result?

   Well, I don't have the link or info about this but I do know that I'm diggin' it! I'm now enjoying my system even more! I'm amazed of how much I could squeez out of these cheap pair of Fostex in my crappy looking plywood cab! Well, back to enjoying the music! Woo Hoo!

Take care,
Buddy

[oldtimer]

I have a pair of Visaton B200's in OB. I will try this and report back. If there is going to be a change in sound I will hear it.

Nigel

[andyr]

 Anyway, as for the theory behind this ... I think this have to do with the driver's voic coil responding to the grounded speaker chassis. Maybe this give a better control of magnet field? Or with grounded chassis just like grounding amp chassis this helps blocking out the RFI and EMI getting to the voic coil? ...

This appears to make some sense but there's "grounding" and then there's "grounding"!   

To "ground" the speaker chassis (spider?) does sound like it might be a good thing to do in a magnetic field (to drain off any magnetically-induced currents in the metal chassis) but I would say this should be done to the earth pin of the nearest mains wall socket ... not the black/return binding post of the speaker.

The reason ... because this binding post is connected to the black/return output binding post on the amp and, if you have an amp which uses a feedback loop, the magnetically-induced currents you are draining off are probably interfering with this feedback loop!   

Regards,

Andy

[SET Man]

 Anyway, as for the theory behind this ... I think this have to do with the driver's voic coil responding to the grounded speaker chassis. Maybe this give a better control of magnet field? Or with grounded chassis just like grounding amp chassis this helps blocking out the RFI and EMI getting to the voic coil? ...

This appears to make some sense but there's "grounding" and then there's "grounding"!   

To "ground" the speaker chassis (spider?) does sound like it might be a good thing to do in a magnetic field (to drain off any magnetically-induced currents in the metal chassis) but I would say this should be done to the earth pin of the nearest mains wall socket ... not the black/return binding post of the speaker.

The reason ... because this binding post is connected to the black/return output binding post on the amp and, if you have an amp which uses a feedback loop, the magnetically-induced currents you are draining off are probably interfering with this feedback loop!   

Regards,

Andy

Hey!

    Andy, good point about amp with feedback. But still I don't think this will cause any interference with the feedback loop... than again I'm not an expert on amp design.

   Okay just to point out... I'm using a pair of SET monoblocs with no feedback. And my speaker are Fostex FE167E of which are magnetically shielded. I'm make the grounding connection on the front as show on the photo I posted. I'm not sure if the metal... steel I think.... shielding cup that cover magnet is connect with the chassis in a way that the it conduct the electrical flow. If so than that the magnet itself also have grounding shield around it too.

  Anyway, thanks for your input on this... yes I think this have to do with the magnetic field.

Take care,
Buddy

[SET Man]

I have a pair of Visaton B200's in OB. I will try this and report back. If there is going to be a change in sound I will hear it.

Nigel

Hey!

  Nigel, yes that would be great... as long as you are comfortable doing it.

   I'm talking about change... improvment in my case... of full sound spectrum here from low end to high end!

   Please let me know your result. This could be a great but so far obscure tweak for single driver speaker like Fostex and etc.

   Not sure about multi-way speaker system but it might work too. But if you going to try do so at your own risk... especially with SS amp!

Take care,
Buddy

[moray james]

the best place to make the connection to ground is ritght at the motor top plate but this is not all that easy to do so the next best place is on the speaker chassis. You will need to take a metre and check to see if you have continuity between the chassis and the top plate (don't forget the paint on the chassis). Most chassis frames are rivited or bolted to the top plate and so there is connection between the top plate and the chassis. As long as you have contact between the chassis and top plate then you can simply solder a small piece of wire between the negative contact and the rivit that mounts the terminal strip to the chassis. This is neat and clean and can be easily removed. You can have a look over at myasylum in the High Efficiency section and search under moray+james+tweak and there should be a bunch of responses of people who tried this.  This mod seems to work well on all kinds of drivers. If you try this mod make sure that you experiment to both the negative as well as the positive terminal. I have even used a three position switch so that the mod can be disconnected or switched between pos or negative connection as some amplifiers seem to have preferences that might be due to some amps inverting. It's a nice tweak anyway. Regards Moray James.

[moray james]

As I mentioned in the above post you can make your ground via the negative speaker connection which on a single ended amp is grounded. There is a slight twist that you might also want to experiment with. You will need to drill a small hole into the backplate of your driver so that you can mount a small tab connector to the back plate (which is your central polepiece) using a small self tapping machine screw. This way you can then connect your negative speaker connection to the top plate as mentioned in the previous post and your positive speaker to your backplate/polepiece. These two parts are electrically separate so there is no worry of shorting. Regards Moray James.

[SET Man]

As I mentioned in the above post you can make your ground via the negative speaker connection which on a single ended amp is grounded. There is a slight twist that you might also want to experiment with. You will need to drill a small hole into the backplate of your driver so that you can mount a small tab connector to the back plate (which is your central polepiece) using a small self tapping machine screw. This way you can then connect your negative speaker connection to the top plate as mentioned in the previous post and your positive speaker to your backplate/polepiece. These two parts are electrically separate so there is no worry of shorting. Regards Moray James.

Hi,

    I see I think I must have read your post or maybe others a few years about this and just remembered it.
 
Hmmm.. positive on the pole piece? You mean the metal part at the back of the magnet right? If that is the case I wil have a little problem... my driver is shielded and have a metal cup covering the magnet.

     Anyway... Thank you for the tip.... I will keep that inmind next time I open up my speaker. I'm just too lazy lately to do anything like that But the sound now with the grounded chassis like in the picture sounds great. I will think I will just leave it like that... for now

But Moray, can you explain to me in detail why this little tweak work? I know it works but I'm still not sure why? But I think it got to do with magnet field right?

Take care,
Buddy

[moray james]

Buddy: have not got that explaination for you, sorry. You cant very well try this on your shielded driver but you could use some more gator clips and try it on your tweeter. Regards Moray James.