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Old 9th November 2008, 11:41 AM   #21
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Quote:
Originally posted by lineup
I believe!
Now I will be quiet and maybe hear our God .. finally
If I may guess it is one no-global-feedback design
I can not imagine such a fast amplifier can work with FB

Quote:
Originally posted by fab


...and how can a no-global-feedback design do THD of 0.000012% ...
Combination of global as well as local feed-back. Anyway thanks for the comments guys it is appreciated, I believe that we have achieved the goals set out for us.

Nico
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Old 9th November 2008, 12:40 PM   #22
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Quote:
Originally posted by darkfenriz
From the waveform one can see very little slew rate limitation, it is rather a first order filter limitation.

If that is really 250kHz, the waveform indicates a bandwidth of around 2-3 MHz (-3dB). It looks really like a square passing through RC.

Guys, could imagine this waveform compressed in time by 10 times, will that still be a nice square? It would be "only" 2,5 Mhz.

Nico, you might have designed a great amplifier, but the -1dB at 7,4Mhz is simply unbelievable to me, sorry.
I have a little experience in designing amplifiers for test equipment whilst at Hewlett Packard, the requirement for wide band linear amp for a "audio" function/signal generators operating from 15mH to 15 MHz was not uncommon.

By the way in this particular design, I was not the designer it was a team effort and I was only the project leader.

We do all kinds of development work, this was our first audio project. What was interesting, the customer was looking for a new approach as they have a legion of audio designers and a company thousand times larger and probably far more capable than us in this field.


We undertake very weird projects ranging from that of tracking people, frequency agile communication jammers, sonar, anti-lock brake systems and many more.

Interestingly, engineers working in a multitude of technologies sometimes create radical solutions.

Most of you outmatch my capabilities as an audio designer. Most of you forgot what I am still about to learn, that was my reason for opening this thread - was there something we missed.

I take a previous comment with caution, that of driving a real load. Real loads could vary by orders of magnitude.

I think those of you in the audio business have far better understanding of what can be hung on the ***-end of an amplifier.

However, we worked purely on a user requirement and trust this is what was needed.

Thank you all again for your participation and on this note I will close the thread.

Kindest regards

Nico
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Old 9th November 2008, 01:33 PM   #23
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Quote:
Originally posted by Nico Ras
- was there something we missed.
Of course… schematic in some, for you, acceptable form. Otherwise, statement: “Most of you forgot what I am still about to learn, that was my reason for opening this thread ” is ridiculous! If everything in this tread remains as is up to now, neither you nor any of us here will learn anything. In that light, similarly ridiculous is the question: “was there something we missed?” when no one ever saw even coarse sketch of topology you have used!? How on Earth are we supposed to know have you people missed something or not?
Everyone have to respect barriers you mentioned (bound by commercial contract), but then this can be seen just as a nice info or advertisement. With all due respect for your efforts and achieved results, that is the only logical way I can look at this tread.
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Old 9th November 2008, 01:36 PM   #24
fab is offline fab  Canada
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Quote:
Originally posted by AKSA
Thank you Nico,
...and can see that you have built and tested many amps over the years. Significantly, you do not appear to be constrained by convention. I take my hat off to you (along with several others here!); progress depends upon unreasonable men......
Cheers,
Hugh
Quote:
Originally posted by Nico Ras

...Thank you all again for your participation and on this note I will close the thread.

Kindest regards
Nico
Nico, you just catch your attention and we are eager to know more on this little treasure....

I think Hugh said it right, we need peoples like you to search for new ideas...

Does it mean that you wil show some info on this design on your web site?

Thanks again.

Fabien
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Old 9th November 2008, 01:41 PM   #25
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Default DIY or Advert?

If its not a DIY project whats it doing here? Free advertising? I'd love to build one but that seems unlikely if its a commercial product are you releasing the circuit diagram again if not whats it doing here?

I'm not trying to insult or offend just asking what seems to be an obvious pertinant question.

RC

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Old 9th November 2008, 03:38 PM   #26
darian is offline darian  France
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Default Too bad we won't have any schematic.

It sounds like a lost cause. It was not worth teasing everyone I guess. To get the low distortion at 1MHz and the stellar bandwidth at 7MHz or so you probably need a very heavy feedback (maybe heavy is even not enough) and a "current type" one. That's all I can figure. You can't get that from some very good diamond buffer topology even with loads of several thousands ohm, so if you can get that with a 8 ohm load I am amazed! Maybe Nico could give us some hints about the general topology or at least how complex this design is (lets say how many transistors in the amplifier schematic...).

Regards
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Old 9th November 2008, 04:02 PM   #27
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Quote:
FOUR PAIRS OF 2SK1058 AND 2SJ162
If the specs are indeed true then we should be seeing full page ads in Hifi magazines for whatever company is funding this.
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Old 9th November 2008, 09:42 PM   #28
syn08 is offline syn08  Canada
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Default Re: Fast Class A Amp

Quote:
Originally posted by Nico Ras
THE THD AT 1 MHZ 0.003%. AND AT 10 HZ 0.0002%. aT 1 KHZ IT IS 0.000012%

TWO TONES 19KHZ AND 20 KHZ GIVES INTERMODULATION PEAKING AT -134 AND -138 DBC, JUST BELOW THE NOISE.

I AM USING FOUR PAIRS OF 2SK1058 AND 2SJ162
Get real. This is almost unrealistic even in Spice simulations.

Smells like another disguised advertising :bs:

Show us the schematics and the measurement setup or get your stuff elswhere.
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Old 9th November 2008, 09:59 PM   #29
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Default Re: Re: Fast Class A Amp

Quote:
Originally posted by syn08


Get real. This is almost unrealistic even in Spice simulations.

Smells like another disguised advertising :bs:

Show us the schematics and the measurement setup or get your stuff elswhere.
What makes you think I need stuff from you? Do you share things you get paid for, if so you will not have a job. Have fun looking for something free.


By the way get a better simulator, free is not good.
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Old 9th November 2008, 10:01 PM   #30
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Default Re: Re: Fast Class A Amp

Quote:
Originally posted by syn08


Get real. This is almost unrealistic even in Spice simulations.

Smells like another disguised advertising :bs:

Show us the schematics and the measurement setup or get your stuff elswhere.
I notice you have a copyright statement on your web site - why not everything for free, post the stuff here.
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