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Old 22nd January 2013, 05:08 AM   #11
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This is great! I have learned more in the last two days about this stuff. Contacted Plitronic today.
The shematic for the +/-35VDC shows a DBA40C rectifier, two 10 000uF capacitors and 2 500 ohm resistors. What type of electrolytics, how much voltage and how many watts resistors? Could you please give me a brief explanation on the correlation between the rectification, wattages and voltages and how/ why they change from the Transformer to regulators? BTW. What am I to use to regulate?
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Old 22nd January 2013, 07:54 AM   #12
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Whoa, there.
You've posted a PDF schematic of the Blue Sky monitors and an image of an STK4044 PCB module assembly.
I think you are talking now about the design of the module PSU. Is it possible to post or link that if it is copyright material?
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Old 22nd January 2013, 09:57 AM   #13
JMFahey is offline JMFahey  Argentina
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FWIW the Blue Sky schematic states "Confidential Information" on its first page.
Anyway they seem to have self-protected by posting a couple bad values to confuse any possible counterfeiter who wants to steal their work.
The amp as shown will burn the Tweeter in milliseconds and the Woofer will be as muddy as the river Nile banks after a flood.

As of the STK modules, I guess they want to sell many of them and so they freely offer suggested schematics to potential buyers.

I think you will lose more than you might win by replacing the internal amps (which after all have been tweaked for those drivers) bny external "flat" amps.

I repeat my suggestion that the "problem" (if any), lies more in the speakers than in the electronics.
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Old 22nd January 2013, 01:30 PM   #14
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Well, the Blue Sky schematic was emailed to me when my blue skys went South. I have since sold them. The STK4044 is an example cicuit from Sanyos datasheet. I can remove them. I am not trying to violate anything or anybody. If the circuit is good then they should be proud, if in fact Blue Sky is selling junk for $2200, then who is really in violation?
Should I remove the schematics?
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Old 22nd January 2013, 02:35 PM   #15
JMFahey is offline JMFahey  Argentina
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Well, not a Lawyer by any means, so don't call me when you shoot somebody , but common sense *seems* to say:

1) as far as the STK/Sanyo/whatever *parts*, their Manufacturers *want* you to use them ($$$$$$ for them) so they design and distribute applications using them.
They keep intellectual property, of course, but implicitly allow and even encourage you to use it.
Damage? : quite the contrary.

2) End Product manufacturers , on the contrary, want you to buy what they made, and frown on competitors copying them , which *includes* DIY (in my personal opinion).
That can very well be considered "damage".
*But*, there is an accepted exception, which is called "Fair use" or something (don't quote me) which applies to any and all Intellectual Property, which recognizes that there are *some* limited uses which don't mean "damage".
One such use is sharing part of that information with fellow knowledgeable people (Technicians or Engineers in this case, might mean fellow Doctors/Lawyers/Architects/etc.) for useful opinion or help in solving a problem.
Which seems to be the case.
You are worried about some Tech problem with your speakers, you share *part* of the data with Techs at a dedicated Forum asking for help.
You are not sharing the PCB artwork (*THAT* is a big no no and very easy to prosecute), cabinet blueprints, transformer winding and lamination data, speaker data, etc. , so "just a part of schematic" wouldn't help that much to a competitor, would it?.
So as long as you don't provide blueprints or disasemble the speakers showing internal "secrets", etc. , don't think there's much harm done, if any.
And of course, if Blue Sky (or somebody who acquired their rights) writes you a letter asking to pull the schematic, by all means comply.
But until then ......

3) in fact Blue Sky sent you flawed info which, if followed, would make you destroy your expensive speakers, how's that?
In the schematic they show active crossovers with a frequency around 450Hz
The woofer will survive it, although with muddy sound, but the Tweeter, as I said before, will have a life measured in milliseconds, specially considering it's driven by a 100W RMS , and there's no limiting circuit visible *anywhere* in that schematic.

So, it looks the other way, doesn't it?
Blue Sky sent you a schematic which if blindly followed would result in the destruction of the cloned product.
Not only that, it would mean the certain destruction of your own, legally owned and paid for speakers, if you happened to try to "restore it to Factory Specs" , how's that?

Naughty naughty Blue Sky

PS: I'm a pencil and paper guy, but if somebody wants to simulate the crossovers built around U2b and U3a , please do and publish the curves.
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