Having reading a number of recommendations regarding the use of “Star” Grounding in the wiring of loudspeaker crossovers, ostensibly to lower noise in the loudspeaker circuit, it appears to me that the use of grounding in the high-level signal path may be comparable to that used elsewhere in the audio circuit (in application, if not in importance). So fa I have been playing around with using a ground plane in the external (passive) crossover enclosure, although I haven’t been able to draw any conclusions so far.
Today, while reading J.A.’s review in Stereophile of the Esoteric MG20 Loudspeaker, I notice that the design employs 5 binding posts. According to the reviewer: “…one pair each for the tweeter and the woofers, and a fifth that grounds the amplifier’s output to the drive-unit chassis…doing so with conventional amplifiers is said to reduce the noise floor by shielding the voice coils from RFI.”.
I'm intrigued and intend to experiment more with this,wondering if the idea of grounding & shielding can/should be extended to include the use of shielded speaker cables and/or running a seperate ground lead from the amp through the (external, in my case) crossover to the loudspeakers...
Anyone else here experimented with this, or have knowledge to share about this topic?
-Chas
Today, while reading J.A.’s review in Stereophile of the Esoteric MG20 Loudspeaker, I notice that the design employs 5 binding posts. According to the reviewer: “…one pair each for the tweeter and the woofers, and a fifth that grounds the amplifier’s output to the drive-unit chassis…doing so with conventional amplifiers is said to reduce the noise floor by shielding the voice coils from RFI.”.
I'm intrigued and intend to experiment more with this,wondering if the idea of grounding & shielding can/should be extended to include the use of shielded speaker cables and/or running a seperate ground lead from the amp through the (external, in my case) crossover to the loudspeakers...
Anyone else here experimented with this, or have knowledge to share about this topic?
-Chas
/sreten.
I would tend to agree and extrapolate the post above, grounding seems to be more or less a mess.
Having to connect several different audio equipments together, with/witout grounding can be pretty frustrating - at least in a home environment. Adding "grounding" to loudspeakers scares me a little bit more..
Having to connect several different audio equipments together, with/witout grounding can be pretty frustrating - at least in a home environment. Adding "grounding" to loudspeakers scares me a little bit more..
Tannoy use a separate ground terminal on their own "Prestige" series loudspeakers, as well as the Esoteric MG series speakers, which they make for Teac.
"The Prestige line employ a unique fifth speaker terminal in addition to a bi-wire pair...With the driver chassis grounded via the 5th terminal, and by using appropriate speaker cable, this proven technology ...electrically earths the driver chassis to dramatically reduce radio frequency interference circulating in the hi-fi system. Eliminating this RF ‘noise’ brings substantial improvements in mid-range clarity and further enhances the soundstage imaging."
They imply using either shielded cable or a separate ground wire. I'm not sure how well this works, but for a commercial design they do use good parts(hardwired crossovers, Hovland & Clarity Caps, van den Hul wiring, etc.) and build to a very high standard.
-Joe
"The Prestige line employ a unique fifth speaker terminal in addition to a bi-wire pair...With the driver chassis grounded via the 5th terminal, and by using appropriate speaker cable, this proven technology ...electrically earths the driver chassis to dramatically reduce radio frequency interference circulating in the hi-fi system. Eliminating this RF ‘noise’ brings substantial improvements in mid-range clarity and further enhances the soundstage imaging."
They imply using either shielded cable or a separate ground wire. I'm not sure how well this works, but for a commercial design they do use good parts(hardwired crossovers, Hovland & Clarity Caps, van den Hul wiring, etc.) and build to a very high standard.
-Joe
Attachments
Thanks, Joe for the confirmation.
Not that I lack originality, but alot of the ideas I get and things I try are inspired by and based upon extrapolation of ideas and techniques I see elsewhere.
I biwire my external crossovers and use star-grounds because these are common practices in high-end designs used by credible designers. The folks at Tannoy have used the 5th terminal to ground the woofer baskets in their top models as well as the Esoteric MG series; Consequently, I'm experimenting with and researching this concept.
In Joseph D'Appolito’s book, "Testing Loudspeakers", he writes:"…in practice, cross-coupling in the crossover networks and the common ground wire introduce low frequencies into the tweeter and high frequencies into the woofers. This makes the case for bi-wiring."
If audio signals can couple(treble into woofer and bass into tweeter)via the "common-ground"(I prefer to view these as "signal+/signal-" leads), then isn't it logical to assume that some RFI can get in as well?
In low-level circuits, we employ star-grounds and shielding to deal with this...
Another trick I'm experimenting with is a shunt RC filter across the speaker binding posts (a'la Walker H.D.Links, Enacom, etc.). Some people simply use 10ohms/.01uF; however, the optimum value of R and C for a particular system depends upon speaker impedance, as well as the characteristic impedance of the speaker cables.
-Chas
Not that I lack originality, but alot of the ideas I get and things I try are inspired by and based upon extrapolation of ideas and techniques I see elsewhere.
I biwire my external crossovers and use star-grounds because these are common practices in high-end designs used by credible designers. The folks at Tannoy have used the 5th terminal to ground the woofer baskets in their top models as well as the Esoteric MG series; Consequently, I'm experimenting with and researching this concept.
In Joseph D'Appolito’s book, "Testing Loudspeakers", he writes:"…in practice, cross-coupling in the crossover networks and the common ground wire introduce low frequencies into the tweeter and high frequencies into the woofers. This makes the case for bi-wiring."
If audio signals can couple(treble into woofer and bass into tweeter)via the "common-ground"(I prefer to view these as "signal+/signal-" leads), then isn't it logical to assume that some RFI can get in as well?
In low-level circuits, we employ star-grounds and shielding to deal with this...
Another trick I'm experimenting with is a shunt RC filter across the speaker binding posts (a'la Walker H.D.Links, Enacom, etc.). Some people simply use 10ohms/.01uF; however, the optimum value of R and C for a particular system depends upon speaker impedance, as well as the characteristic impedance of the speaker cables.
-Chas
Ground "heaven" for speakers is the storage caps at the power amp. Or in practice the negative terminal of the amp. This as another post suggests bi-wire.
Don't use ground planes on passive X-overs, just causes problems. Besides they don't shield magnetic coupling anyway which is more important here.
To reduce cross coupling and feed thru between drivers circuitry, watch the orientation or better yet spacing between inductors is key.
Don't use ground planes on passive X-overs, just causes problems. Besides they don't shield magnetic coupling anyway which is more important here.
To reduce cross coupling and feed thru between drivers circuitry, watch the orientation or better yet spacing between inductors is key.
Advice needed please, friends!
I have heard that some people and indeed some speaker companies ground the individual drive units in their speakers to earth. So....
I am considering grounding all the drive units in my ATC SCM150ASL active speakers. These monsters have their own active crossover and three amps, one each for bass, mid and treble. My plan is to connect an earthing cable to each drive unit chassis, then take these 3 cables to a single earth point on the back of the cabinet, and from there take the earth EITHER to the mains power supply earth OR to a copper rod in the ground outside.
My question is: Is there any danger of the new drive unit earthing causing a problem if the negative of the internal speaker cables happens ALSO to be connected to a drive unit's chassis? And might it also cause hum because of a ground loop? Any advice would be very welcome. Thank you.
I have heard that some people and indeed some speaker companies ground the individual drive units in their speakers to earth. So....
I am considering grounding all the drive units in my ATC SCM150ASL active speakers. These monsters have their own active crossover and three amps, one each for bass, mid and treble. My plan is to connect an earthing cable to each drive unit chassis, then take these 3 cables to a single earth point on the back of the cabinet, and from there take the earth EITHER to the mains power supply earth OR to a copper rod in the ground outside.
My question is: Is there any danger of the new drive unit earthing causing a problem if the negative of the internal speaker cables happens ALSO to be connected to a drive unit's chassis? And might it also cause hum because of a ground loop? Any advice would be very welcome. Thank you.
When I assembled my ATC SCM150 loudspeakers, I decided to install cables connected to each chassis ready to earth each drive unit, BUT when I checked with my multimeter, I found that SOME of the chassis were already connected to the negative terminal of each drive unit and some weren't. Which made me think that if I did connect them all together, I would at best create a ground loop, and at worst I might be causing a problem for the amp.
But the other (middle case) scenario concerned ATC's Super Linear drivers....ATC's range in recent years has speakers which use an electrically insulating layer in the loudspeaker magnet assembly which makes the bass and midrange driver more linear and reduces distortion significantly, compared to their older (non-SL) drivers.
As a consequence of all of the above, I decided NOT to connect the earth cables which I had installed, to each other at an earth terminal at the back of the loudspeaker, to ensure there was NO risk of possible amp damage or distortion. Sometimes it is best to leave well alone!
But the other (middle case) scenario concerned ATC's Super Linear drivers....ATC's range in recent years has speakers which use an electrically insulating layer in the loudspeaker magnet assembly which makes the bass and midrange driver more linear and reduces distortion significantly, compared to their older (non-SL) drivers.
As a consequence of all of the above, I decided NOT to connect the earth cables which I had installed, to each other at an earth terminal at the back of the loudspeaker, to ensure there was NO risk of possible amp damage or distortion. Sometimes it is best to leave well alone!
Hi AllenB.
I have heard of it many times....Tannoy in particular, and on some Linn forums...
As usual there are always opposing views, but google 'loudspeaker earth or earthing" and you'll find some interesting opinions.
Also here, on the Tannoy site: (Tannoy being one of the most famous (and conservative thinking) British loudspeaker manufacturers.)
Earthing / Grounding of Tannoy speakers – Tannoy Support
I have heard of it many times....Tannoy in particular, and on some Linn forums...
As usual there are always opposing views, but google 'loudspeaker earth or earthing" and you'll find some interesting opinions.
Also here, on the Tannoy site: (Tannoy being one of the most famous (and conservative thinking) British loudspeaker manufacturers.)
Earthing / Grounding of Tannoy speakers – Tannoy Support
I've heard Steve McCormack describe the results from connecting the ground lugs on the Tidal Audio Akira speakers to his AC Nexus distribution box ground posts as "mind blowing" and "a real eye-opener".
Mind you the Tidal Akiras cost $215,000 and the AC Nexus $20,000. But he goes on to says that the results of grounding any metal parts in a speaker are unambiguous and hopes the idea catches on with speaker manufacturers.
I tend to listen when Steve McCormack talks.
Mind you the Tidal Akiras cost $215,000 and the AC Nexus $20,000. But he goes on to says that the results of grounding any metal parts in a speaker are unambiguous and hopes the idea catches on with speaker manufacturers.
I tend to listen when Steve McCormack talks.
When I hear terms like that, I suddenly imagine I'm standing behind a bovine and something solid and damp has just fallen on my feet.
It's generally not advisable to drain a noise current into an audio reference ground. Better to drain noise currents from screens (or wherever) to an electrical or chassis ground away from amplifying circuits. Current cannot flow without a voltage drop so, as consequence of Ohm's Law (and unless the circuit has very carefully designed star earthing strategy) noise current injected into a reference ground turns that conductor or PCB track into a noise voltage generator.
(This is one of the benefits of balanced connections, i.e. keeping noise currents away from audio circuitry. If the AES recommendations for balanced connections are adhered to, the cable ground connects only to pin 1 of the XLR connector, which in turn connects only to the chassis at the point the signal enters the unit.)
Because such hyperbole is tantamount to BS, especially when any effect, if it actually exists, would be at best trivial. I'm happy to be proven wrong with some independent measurements showing an audibly significant effect. Until such is provided...