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Old 2nd October 2011, 08:06 PM   #1031
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Quote:
Originally Posted by AndrewT View Post
Testing hFE at constant Ic is a little more consistent than using constant Ib.

I always use constant Ic now, for hFE measurement even though I don't know Tj.

Multimeters, with a give away for free hFE tester built in, generally use constant Ib.
They are no better than a batching tool. The problem is that one does not know what Ic is.
Multimeters usually have fixed Ic to 1mA, but that is usually not accurate enough for comparison between power transistors.

hFE measurement at Ic=100mA is just a fine compromise between accuracy and power dissipation vs. temperature dependency.

At mine proposed NPN/PNP measuring schematic no formula calculations are necessary, mV reading is actually hFE data.
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Old 2nd October 2011, 08:57 PM   #1032
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Quote:
Originally Posted by Smiley 09 View Post
Dear Mr. Andrej

Thank You very much for the most beautiful SSA-V12 version.
You make me the beautiest day since long time awaiting for something to drive my speakers civilized - and You make it.
I know, this is the most Generous Scorpio's gift, You give to the whole worldwide sound-lovers & audio community. Thank You ...

Long Live & let God bless You . .

Andreas
Thank you Andreas

I couldn't even think the SSA Balanced V-12 schematic would make you so happy, I'm really glad it did.

I realize XLR-RCA input connection should also be explained, so here it is.
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Old 2nd October 2011, 10:27 PM   #1033
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Originally Posted by Lazy Cat View Post
I saw you have very small Ic in input pair, is that OK, cause usually input transistors should work at 1-5mA collector current. That also means smaller influence of parasitic capacitances if the collector current is larger, which finally brings you wider bandwidth and higher slew-rate, all though I saw yours sim already shows 380V/us.
Thank-you, on that mod, I wanted to propose as less modifications of original values as possible. But you are right, will see if any improvement in increasing the current in the input trans, witch was supposed to be 0.2 ma in the original schematic, very good sounding, in fact. A way too to reduce the values of feedback resistances as you like.;-)
You only can be impressed by yourself, it is just your idea !
I'm more interested to have your opinion and expert suggestions on my differential protection circuit idea.
http://www.diyaudio.com/forums/digit...ml#post2731810
If you like-it, i would be very happy to see-it added to you nice SSAs.
I'm working on an integrated solution: Remote power-on of the amp from the 12v preamp rail, soft power with a current limited delay of 2 sec to take care of the power caps and switch on the Loudspeakers after 4 more seconds or so with this "protect against everything" instant reactive circuit.

I will not leave your thread for no price, i just do not want to bore-you with less noise as possible :-).
As i said, you deserve my sympathy for your passion, generosity and brilliant expertise, makes-me remember when i was young, so many years ago ;-)
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Old 2nd October 2011, 11:08 PM   #1034
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Originally Posted by Lazy Cat View Post
Yes, this circuit test a transistor at constant collector current level you choose with SW combinations, but the same temperature dependency appears here, base current will go down with temperature rising, so matching is again time dependent. For simplicity and relative only comparisons sake I suggest you to built simpler one.
Thanks LC for your straight forward answer and brilliant advise. Appreciate it.
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Old 2nd October 2011, 11:15 PM   #1035
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Thumbs up Elegant as always . . .

Quote:
Originally Posted by Lazy Cat View Post
I realize XLR-RCA input connection should also be explained, so here it is.
Thank You Andrej for the elegant I/P solution.

Now It is my turn . . . . . . to put Yours genie design into best possible harmony with my ultra low impedance speakers.

My best regards to You,

Andreas
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Old 2nd October 2011, 11:48 PM   #1036
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Quote:
Originally Posted by Smiley 09 View Post
with my ultra low impedance speakers.
Some kind of Planar, Orthophase, ot Condenser units ? Ot just paralleled moving coils ones ?
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Old 3rd October 2011, 03:01 AM   #1037
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Default The most difficult Speakers for all amplifiers on the globe

Esperado,

Apogee Scintilla . . .
APOGEE SCINTILLA - MK4.jpg

Theirs sound is so unique that no conventional speakers come even close.

They require an amp with constant ability drive 0.5 ohm all the time.
Impedance is almost flat line and never leave 0.9 ohm.
The sound, .... incomparable with anything You hear till today - Unique.
They require a nice, civilized arc-welder to drive them, but for return
the listener is constantly in heaven

Regards,

Andreas
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Old 3rd October 2011, 05:40 AM   #1038
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What denominations details? R1-R17, C1-C18
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Last edited by Andrej Maximov; 3rd October 2011 at 05:46 AM.
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Old 3rd October 2011, 05:43 AM   #1039
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What denominations details?
R1-R18, C1-C18
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Old 3rd October 2011, 06:07 AM   #1040
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Originally Posted by Smiley 09 View Post
but for return the listener is constantly in heaven
I believed Hifi was dead ! You use ribbons, i use spherical horns, we gone kick the *** of the smartphone's sound ! Did-you tried some good Class D amp for the basses with your crazy speakers ? They love low impedance. Of course, for treble, SSA would sound gorgeous, i presume.
Ps: my impedance line is quite flat too, between 5.9 and 6.5 ohms all the way, that's one of the secrets ;-)
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Last edited by Esperado; 3rd October 2011 at 06:09 AM.
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