What Shunyata and Furman (SMP) Have in common - Inductance!

Hi Sadono,

As far as I know, the license/patent comes from Jack R. Harford / Electronic Systems Protection. Please post a link to any legal documents / reporting regarding licensing issues with Furman.


https://patents.google.com/patent/US4870528A/en

You are completely wrong about Furman SMP using MOV's, I've disassembled them. They do not use MOVs and they are very good. Please see their spec sheet.


https://www.furmanpower.com/furman-technologies/series-multi-stage-protection

In addition to Furman, SurgeX and Brick Wall, the other licensees I know of are PS Audio and McIntosh. Among those, McIntosh charges the most, followed by SurgeX for the same basic technology.  Furman is the most affordable in their $180 power strips.

In regards to Chang, I stand corrected, Chang advertises no coils in their tech. How pathetic, since that essentially means they can't block anything below RFI. Also, their claims are questionable. A well designed coil is a good thing, with no lag, unless you are a surge.   Please go spend tens of thousands of dollars on their gear if that makes you happy.

Best,
Erik

@erik_squires

"Zero Surge® was incorporated in March 1989 by J. Rudy Harford." He is the founder, and was the former owner and president. And yes, he’s the license owner.

https://zerosurge.com/about-us/

Look at the SMP circuit on the page you linked. Are you blind or clueless as to what a MOV looks like? There are clearly MOVs.

https://www.furmanpower.com/sites/furmanpower.com/files/_/Power-Report/smp-circuit.jpg

Still don’t believe me? "Furman’s Series Multi-Stage Protection Plus (SMP+) addresses some of the shortcomings of traditional MOV-based protectors by employing a variety of circuits to clamp, absorb, and dissipate transient voltages without having the device sacrifice itself. The company claims that MOVs used in a properly designed circuit will not fail.

Furman’s SMP+ circuitry takes pages from both shunt-and series- mode playbooks and adds its own twist. Along with a high-voltage MOV and a high-amperage thermo-fuse varistor, SMP+ uses a tuned circuit that includes series inductors, a bridge rectifier (which con- verts AC to DC power), and high-voltage capacitors."

https://zerosurge.com/wp-content/uploads/2016/10/Sound_and_Vision_July2007_Zero_Surge.pdf

"SMP allows Furman products to offer this protection without damaging any of their own internal components—that is, they are virtually non-sacrificial"

https://www.mixonline.com/technology/furman-sound-implement-smp-technology-381312

"• Zero Surge’s patented filter technology protects sensitive electronics from even worst case surges, repeatedly, without degradation or failure. MOV-free."

https://zerosurge.com/wp-content/uploads/2017/09/zero-surge-brochure.pdf

" • No sacrificial or wear components (no MOV’s)"

https://www.brickwall.com/pages/the-worlds-best-surge-protectors

The series mode surge technology patent states, "Provides an inductor system as the first means of protection."

"A branch circuit SPD (Surge Protection Device) using an MOV in front of, in back of or sideways of, a small ferrite core series inductor, labeled as ’series something’, is in my opinion, a marketing persuasion by our competitors intended to ride on our back and confuse you, and the only way to promote a product ’looking like ours’ without violating our patents. Are you a Switch or a Filter?

An MOV is a semiconductor switch. Switches will wear out and can suddenly fail when stressed. The monitoring of these switching devices over time as ’functional’ is tedious and a guessing game at best. A filter properly designed for its application will not wear out and will only fail if misapplied. Think about your passive LC subwoofer crossovers...when will it wear out?...perhaps when you wire it up to 440V just for fun?...or when you listen to too much music?" Michael McCook, SurgeX International

Furman purposely added MOVs to create a hybrid surge protection device that does not violate the patent. Due to the patent, Furman can not call the design series mode technology, and renamed it SMP+ in 2005.

SurgeX does not have the same basic technology as other series mode designs. They have added ASM (Advanced Series Mode) technology. This adds an extra winding to the air-core inductor to further improve the surge protection and lower the let-through voltage.

https://www.ametekesp.com/-/media/ametekesp/downloads/white-papers/surgex-ametek_white-paper_advance....

You do seem right about McIntosh, as the MPC1500 appears to use series mode surge technology as a repackaged Torus. "Torus Power Technology under license from Plitron Manufacturing Inc."

https://www.mcintoshlabs.com/-/media/Files/mcintoshlabs/DocumentMaster/us/mpc1500om05L.ashx

What led you to believe that PS Audio licenses series mode technology? They use a circuit breaker, fuse, and MOVs for surge protection in the Power Plant regenerators. Paul McGowan does not like large inductors, and advertises how the Power Plant regenerators have low inductance.

Inductance is not good for transparent sound quality. It reduces current and rolls off the highs. Inductors are called chokes for a reason. I won’t deny that many people like them, as evidenced by people that find series mode technology transparent, and all of the Furman & Audioquest fans.

You can’t lump all Furman products together anymore than you can McIntosh and PS Audio. Some use series mode protection, and some use plain old MOVs.  You are misreading the article if you think that all Furman surge suppressors use MOV's. That's' not what they mean to say. They mean to say they sell products with a variety of features.

The products Furman labels as SMP are clearly series mode, non sacrificial components. I make that clear in my blog post that this is the key feature.


PS Audio constantly changes it’s product line. Based on their current web products it’s not clear if they are using series mode protection or not. It was clear in models no longer available on their web site.

Inductance is not good for transparent sound quality. It reduces current and rolls off the highs.

Only if you don’t know how to do AC analysis properly. If you believe this is universally true then you should be advocating the end to all linear power supplies.


Also, hard to tell if you like inductance or not. You seem to say that SurgeX is better than a Furman because they use MORE inductance, but then also want to take the position that all inductance is bad. Have to pick a side here.


Furman also ads LiFT to the strips I recommend, further lowering the noise floor, without adding inductance. That makes them better than a SurgeX, right??

They are specifically talking about the Furman products using the SMP circuit. It is laid out clearly in the circuit picture that it uses MOVs. The same circuit board is used in all Furman products with SMP. I’m sorry to burst your bubble, but it’s the truth.

Yes, your blog is incorrect, too, and you’ve been spreading false information. Read the series mode patent and look at the SMP circuit. There is NO inductor as the first means of protection. Also, no real series mode products use MOVs. This means by legal definition that SMP is not series mode surge protection. It is a hybrid.

The whole point of series mode technology is to avoid the use of MOVs. It’s fully ironic to use MOVs and call it series mode. It would be akin to saying you’re dying of thirst, and then eating the saltiest food you can, or calling a fat guy slim.

What PS Audio products do you think used series mode? I’m sure old reviews can confirm or deny this. They are not a current licensee, if they ever were.

You are misunderstanding things. I’m saying the SurgeX ASM products are better surge protectors than Furman, because they use no MOVs.

LiFT is a negative, IMHO, as it digs down into the audible region, and throws the baby out with the bath water. I understand some people like that squeaky clean sound.

Your own link :
https://www.mixonline.com/technology/furman-sound-implement-smp-technology-381312
basically is spec for spec identical to the description of the multi-stage protection described by Brickwall. Down to the clamping voltages. Now stop