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Thread: Patented Infinite Shape Feature (ISF) in Blackstar amps

  1. #1
    Supporting Member Steve A.'s Avatar
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    Patented Infinite Shape Feature (ISF) in Blackstar amps

    This fully interactive control allows you to infinitely adjust the response of the tone control network between any of the traditional voicings. In this way you can design your own sound and truly find the sound in your head.

    Getting The Sound In Your Head

    ISF works in conjunction with the Bass, Middle and Treble controls to give you access to infinite new sound possibilities.
    HT-5RH ISF Details - Blackstar Amplification

    So does anybody here know if this control adjusts the value of the slope resistor? A lot of the amp builders here have been using that trick for many years. (One way to do that is to add a 33k resistor in series with a 100k pot wired up as a variable resistor which gives you a range of ~33k to 133k.)

    Thanks!

    Steve Ahola

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    I actually have a Blackstar... and by "infinite new tone possibilities" they mean about two. That aside, I don't actually know how it works. I'd assume it's some sort of slope control or mid-shift control. I'm somewhat partial to the James tone stack with a mid-shift control. Shifting the centre point around (or making it wider, steeper and so on) seems to give the illusion of 'infinite tone shaping' abilities.

    Although I'd be slightly disappointed if the patent office actually granted them the ability to monopolize the use of a potentiometer in place of a resistor... Never stopped Randall Smith though, haha.

  3. #3
    Site Janitor tboy's Avatar
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    Marshall used a variable slope resistor in at least one amp - the JCM800 Model 2000. The knob was labelled "sweep" and the range was 10k - 110k.
    -tb

  4. #4
    Senior Hollow State Tech Bruce / Mission Amps's Avatar
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    Hmmm... where did it say it was patented? I briefly looked over the site and didn't spot it...
    If not patented (who'd pay to bust it if it was anyhow)... I was under the impression that it was illegal to claim a patent if there is none.

    It does say "patented applied for"... which means nothing good or bad.
    It means they released it thinking they can own it, unless someone at the patent office is alerted or spots the preexisting artwork... etc. I don't think it is the patent office's duty to discovery much though, is it?
    U.S. Patents are a joke anyhow unless you have BIG bucks to fight or defend.
    Bruce

    Mission Amps
    Denver, CO. 80022
    www.missionamps.com
    303-955-2412

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    I spent some time simulating various iterations of their design, trying to figure it out. I don't think I ever came up with the real deal. In the end I concluded I'd rather just stick with one design. You mileage may vary, of course.

    jamie

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    Yes, patent has been applied for it and in fact any patent search engine that can search British patents will find the application document, which the reveals technical details of the circuit. The amps use the circuit depicted in the patent document but the pedals use a different kind of a circuit, which is an active one. No, it's not a variable "slope resistor".

  7. #7
    Supporting Member Steve A.'s Avatar
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    Quote Originally Posted by Bruce / Mission Amps View Post
    Hmmm... where did it say it was patented?
    It uses the word "patented" on the product description pages for the amps that use the feature.

    Quote Originally Posted by teemuk View Post
    Yes, patent has been applied for it and in fact any patent search engine that can search British patents will find the application document, which the reveals technical details of the circuit.
    Can you post the number of the patent application? Or is that one of those things that if you told me you'd have to kill me?

    Thanks!

    Steve Ahola
    Last edited by Steve A.; 12-15-2011 at 09:18 PM.

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  9. #9
    Supporting Member Steve A.'s Avatar
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    Thanks- that is a very interesting circuit!

    Steve

    P.S. I am surprised that you can view and download files from sewatt.com without becoming a member and logging on (since you need to do that to even view the forums). Sometimes I think it must be easier to hack into the Pentagon than to enter the sewatt.com (along with the sibling sites including ppwatt.com).

  10. #10
    Old Timer J M Fahey's Avatar
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    Well, in fact they vary *two* slope resistors at the same time, the low shelving and the high shelving one.
    Nice, and probably works well, but not *that* patentable.
    As has been said above, *anybody* knows that varying parts values (including resistors) changes Tone Control characteristics, and the method of doing so, either with pots or switched resistors "should be self evident to anybody normally versed in the art" , which is a condition stated by the Patent Office. (not the exact words but something very close which means that).
    Would be similar to somebody asking a patent on fitting trimmer resistors to tube cathodes, to fine tune bias, and claiming "I deserve a Patent because I donīt know anybody doing so and canīt find a prior Patent on this subject" ... which may very well be true, of course.
    Iīm not criticizing the idea itself, which I find interesting and probably useful, but the patentability issue.

    *Real* Electronics Guru Don Lancaster has some strong ideas about Patents and their problems.
    If you have some spare time, browse the links shown in:
    "Guru's Lair: Patent Avoidance Library"

    If you have a lot of spare time, browse the rest of his site, very interesting.

  11. #11
    Supporting Member Steve A.'s Avatar
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    Quote Originally Posted by J M Fahey View Post
    Well, in fact they vary *two* slope resistors at the same time, the low shelving and the high shelving one.
    Nice, and probably works well, but not *that* patentable.
    When I look at some of the other patents granted for guitar amps (like a fixed bias/cathode bias switch- or most of R. Smith's patents) I don't find the Blackstar one to be that objectionable. As I recall most of R. Smith's patents included sample values (probably different from what was used in the actual amps but they would get you in the ballpark)- is that no longer required, or just for the patents in the UK?

    Steve

  12. #12
    Old Timer J M Fahey's Avatar
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    Hi steve a
    Please let me be more precise, Iīm afraid I was not.
    If we define "patentable" as something that those hardworking Public workers there can grant, well, thereīs a lot of "Patentable" stuff.
    Their basic "patentability" test for them is whether it was previously patented or not; not much more than that.
    As Don Lancaster explains, the problem is not so much getting a piece of paper stating that such and such thing is patented in your name, but being able to defend it in Court.
    And it can be challenged, not by proving it was already patented (which in theory you are protected against) but simply by showing that *somebody* published it earlier, in a Trade Journal, a Magazine article "somewhere" , *maybe* in some Forum such as ours.
    Please trake a look at:
    http://www.tinaja.com/glib/bustpat.pdf

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    It's funny. There are things I'd be embarrassed to say I held a patent on. I guess I'm just too hard on myself that way.

    I did find that there was a patent issued on the idea of using a variable voltage, variable resistance output on a voltage regulator to fake a dying battery for pedals. It's not mine.

    It was applied for six months after I published the scheme at geofex.

    Silly me. I was taught that to be patentable, any invention had to be NOT obvious to one skilled in the art.

  14. #14
    Old Timer J M Fahey's Avatar
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    Well, that patent, if granted, dies a violent death the very second anybody, not even you, refers to your Geofex article.

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    the isf is stupid.

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    Quote Originally Posted by J M Fahey View Post
    Well, that patent, if granted, dies a violent death the very second anybody, not even you, refers to your Geofex article.
    I don't think this is necessarily true, unless the patent office actually has an obligation to chase up any claims (for free...). Usually court battles are fought over this sort of stuff. In order for something to be patentable it must show an 'inventive step' (whatever the patent office decides this to be) and not be common public knowledge. There have been an ENORMOUS amount of cases fought based on the latter assumption. For instance a rather large pharmaceutical company actually lost the rights to patent their product in Australia because they had patented their product in other countries before doing this in Oz, thus deeming their invention common public knowledge. From there, it was basically free reign for any company in Australia to produce this drug. Note that this case was actually instigated by one their competitors and the patent wasn't simply transferred to anyone; it was actually abolished.

  17. #17
    Old Timer J M Fahey's Avatar
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    Dear exclamation mark.
    Maybe I was not clear.
    I meant the patent dies, not at the Patent office, but functionally, as something that protects you from competition.
    Problem is, infringers usually donīt care to prove anything, they just copy you and pocket the cash.
    *If* you start legal procedures, which considering the expenses and headaches remains a big *if*, only then the accused (which may be only one among many) will have to defend himself, which he can do by referring to an earlier publication ..... or even ignoring you and letting you start and move the case forward.
    The famous litigation cases we all read about, are among Industry giants (Microsoft/Apple/Samsung/Sony/HP/Google) which are fighting for zillions of dollars and have the Lawyer armies (and Political connections) necessary .... but at a smaller scale often itīs out of reach.
    Imagine some Chinese OEM company copies the ISP .... Blackstar may sue them, no doubt, Iīm sure it will be a big headache.
    well, itīs just a personal opinion

  18. #18
    Noodle of Reality Steve Conner's Avatar
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    That document isn't a patent, it's a rejected patent application. Look at the last page.

    Bruce Keir of Blackstar (formerly of Marshall) has one patent which can be seen here:
    Patent US5467400 - Solid state audio amplifier ... - Google Patents

    I believe it is for the thing that Marshall used before Valvestate: FDD or whatever.

    Usually when a small company says "patented" they mean "patent pending". I'm named as an inventor on three or four patent applications, but none of them has ever been granted. Here's one that expired.
    Patent US20040136055 - Automatic power control of a ... - Google Patents
    "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

  19. #19
    Old Timer J M Fahey's Avatar
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    Quote Originally Posted by Steve Conner View Post
    I'm named as an inventor on three or four patent applications
    WOW !!!!!
    And Iīm not kidding

  20. #20
    Old Timer tedmich's Avatar
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    Quote Originally Posted by Steve Conner View Post
    That document isn't a patent, it's a rejected patent application. Look at the last page.

    Bruce Keir of Blackstar (formerly of Marshall) has one patent which can be seen here:
    Patent US5467400 - Solid state audio amplifier ... - Google Patents

    I believe it is for the thing that Marshall used before Valvestate: FDD or whatever.

    Usually when a small company says "patented" they mean "patent pending". I'm named as an inventor on three or four patent applications, but none of them has ever been granted. Here's one that expired.
    Patent US20040136055 - Automatic power control of a ... - Google Patents

    PAF!! indeed

  21. #21
    Supporting Member Steve A.'s Avatar
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    Quote Originally Posted by R.G. View Post
    I did find that there was a patent issued on the idea of using a variable voltage, variable resistance output on a voltage regulator to fake a dying battery for pedals. It's not mine.

    It was applied for six months after I published the scheme at geofex.
    I saw the Dan Electrode DA-4 power supply recently with an adjustable voltage from 3 to 9 vdc... AND it can power up to 15 pedals! Does anybody actually have 15 pedals that sound better at one specific reduced voltage? For a lot of pedals you want the headroom from the full voltage (in fact some of them sound even better with 12vdc, 16vdc or 18vdc). It would make a LOT more sense to me if the DA-4 could supply both the full voltage and a variable voltage at the same time. If you are going to run multiple pedals you are going to need a daisy chain cord so you could plug that into a jack on the wall wart which supplies the full 9vdc. While the cord permanently attached to the wall wart would be the variable supply (set it to 9vdc if you want the full voltage.)

    Dan Electrode

    There was some griping around here when we found out that Sal Trentino had patented the fixed bias/cathode bias switch in the mid-90's as I recall. 6 months before the date of the patent application Dan Torres had included a design for a fixed bias/cathode bias switch in his column for Vintage Guitar magazine. It wasn't his design- someone in Europe had come up with it and mailed him the drawing. What was really cool was that it used just a single pole double-throw switch (most designs would use a DPDT switch). This was specifically for a Fender blackface amp and it did involve replacing one of the resistors in the bias supply circuit.

    I had included a fixed bias/cathode bias switch in my mods for the Pignose G40V so I sent an email to Sal to see if he wanted me to redact it from my article. But he was cool about presenting the switch in a non-profit educational context. It was the amp mfgs who would have to pay him royalties if they were to include it in their amp. (Some of the mfgs got around that by using a fixed bias/cathode bias switch, but calling it something else altogether.)

    I think that patents are great because disseminate ideas rather than hide them under a bushel. We can study the designs- or at least a rough sketch of them.

    Steve Ahola
    Last edited by Steve A.; 12-17-2011 at 06:10 PM.

  22. #22
    Supporting Member Steve A.'s Avatar
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    Quote Originally Posted by Steve Conner View Post
    That document isn't a patent, it's a rejected patent application. Look at the last page.
    Are you referring to the 14 page ISF patent application PDF posted at sewatt.com? I just looked at the last page again and did not see anything that looked like a rejection notice.

    I think that a lot of amp mfgs will submit patent applications with the hope that it might impress potential customers. "These guys aren't just copying everybody else's design- they have come up with something new that can be patented. I need to check that out!"

    With guitars and amps it seems like copyrighted trademarks are enforced more than patents. Like guitar headstocks and body shapes. And possibly the Dumble Overdrive Special logo (it seems like the cloners are afraid to copy his logo although they have no problems copying his designs.)

    Steve Ahola

  23. #23
    Old Timer J M Fahey's Avatar
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    Yes, Trademarks and Logos are *very* easy to enforce.
    Remember you have to convince a Judge, who is versed in other knowledge but not a Technical one , that you are right.
    *Anybody* will notice that your "Dumble" trademark is the same as the "Dumble" Howard patented in, say, 1 microsecond.
    And realizing that your brown sweet carbonated water called "Koka Kola" might hurt Coca Cola would take less than a minute.
    But if , say, the classic TMB Fender tone control were patented, and the infringer had one with doubled Cap values and halved R and Pot values (which ends having the exact same EQ curves) it would be very difficult to defend in Court.
    The infringerīs Lawyer might easily say: "Your Honor, *no* part value in the Defendantīs schematic matches the Patented one" ..... and he would be right.
    I remember the first Tube patent was challenged in Court and almost overturned because the tube was explained to the Judge as "some kind of lamp" and the Judge saw with his own eyes that "it was a very poor kind of Lamp, that it provided very little light"
    I have 1 Patent registered in Argentina and Spain and two Trademarks registered in my name, and my Patent Lawyer always insisted: "provide as little and as generic detail as possible in the Application, or it will be very easy to beat by a minor variation"

    As of the patent linked earlier, I see two contradicting statements at the end :
    1) it says "valid from 01/01/2006) on" which looks like it was granted after all , and
    2) the first three "claims" which define what is *really* being patented are crossed with an "X" , "because they exist on earlier patents" , more specifically they say that there exists a "document indicating lack of novelty or inventive step" which is ground for denying.
    All other earlier patents mentioned are labelled "A", which maybe does not hurt.
    Or maybe I understood it upside down.
    Really not sure, Iīm not a Lawyer.
    Maybe Steve Conner knows better by being in closer contact with this stuff than us.

  24. #24
    Supporting Member Steve A.'s Avatar
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    Quote Originally Posted by J M Fahey View Post
    But if , say, the classic TMB Fender tone control were patented, and the infringer had one with doubled Cap values and halved R and Pot values (which ends having the exact same EQ curves)
    I agree that they should have the same EQ curve but I was wondering if anybody has tried doing an A/B test with those two tone stacks.

    Steve

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    probably wouldn't be too much different except in the way that the EQ interacted since you'd need different pot values.

    looking over some of the schematics I have...it seems like you'd generally need a .1 and a .2 400v rated cap. those get pretty big...


    actually looking over it some more I'm not sure if that would technically be possible or as easy as simply halving and doubling...

    the initial filter values are selected in relation to the output impedance of the triode stage.

  26. #26
    Old Timer J M Fahey's Avatar
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    I agree that they should have the same EQ curve but I was wondering if anybody has tried doing an A/B test with those two tone stacks.
    It was just an example on the not-so-perfect patent protection provided to many electronics circuits.
    Donīt read too much into it.
    Thatīs why. AFAIK, actual schematics are not patented, while, curiously, their *drawing* may be protected (as work of art).
    As of the results, a same-curves halved impedance wonīt work the same if driven from a triode plate (as in BF/SF Fenders) with its relatively high intrinsic impedance, but I *guess* (didnīt do the Math, may be wrong) that when driven by a cathode follower the difference may be barely audible, if any.
    When driven by an Op Amp, the difference is inexistent for all practical ends.

  27. #27
    Supporting Member Chuck H's Avatar
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    It's all about who actually knows what's going on. "WE" here at AMPAGE (or MEF, whatever) know and exploit all manor of circuit manipulation and see Randall Smith's patents and this BlackStar patent as pedantic. But we are an obsessive bunch. We know that in an overdriven guitar amplifier the slope resistor can make or break the overall tone. To a patent court, that AT BEST has the consultation of some lab coat EE, the slope resistor is a pedestrian issue based purely in the final balance and knee frequencies. Add the caveate that the amp is intended to be overdriven, so all inclusive chaos must be considered, and any consulting EE will throw up their hands. Forced to admit that the refinement of overdrive is a black art that is opposed to any schooling or known technologies. At this point the decision must be made based on the FACT that no one in the loop besides the claimant has a real clue about what's going on... Pattent granted. Even if some minority (like us) knows it's old news, we don't happen to be in on the arbitration. That's how these patents get granted. The only thing anyone wanting to use patented technology, as it applies to guitar amps, has is the likelyhood that they can demonstrate a precident. Which has become eminently more possible with information technologies.

    JM2C
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    i think the bigger issue is that people in the know and who aren't trying to make money off their ad copies realize that the type of circuit given in the isf is pretty much worthless.

  29. #29
    Old Timer J M Fahey's Avatar
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    I think being able to change the tone controls frequency turnover points has some practical utility.
    The example graphs show it can go from about 250Hz (classic Fender) to 750Hz (beyond Ampeg.
    A 3:1 frequency change is *very* noticeable.

    Too tired to draw now, but Iīll post two variable turnover tone controls I used successfully in many amplifiers; one of them with a 3PDT switch changing treble control frequencies 5:1 (*very* noticeable) and another one with a midrange slope pot.

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    right but it's all about how that ends up working within the rest of the circuit.

    The graph does show a noticeable shift but the turnovers are also interacting with the rest of the tone controls.

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