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Old 29th August 2008, 12:42 AM   #11
lineup is offline lineup  Sweden
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Thumbs up The Voltage Supply = 120 VDC regulated

.
As this amplifier needs a well regulated power supply
at 120 Volt Direct Current, DC
... which is pretty high, except in compare to great Tube / Valves circuits

.. I will use my own precision 120 Volt Discrete Regulator

as this regulator has been posted already twice ( 2 times )
i need not post it here again

my readers will have it in their collection of good discrete regulated power supply schematics,
in the folder named: Lineup Circuits

basically uses one TL431 for good temp stabilty reference
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Old 29th August 2008, 01:34 AM   #12
GK is offline GK  Australia
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Default Re: The Voltage Supply = 120 VDC regulated

Quote:
Originally posted by lineup
.
As this amplifier needs a well regulated power supply
at 120 Volt Direct Current, DC
... which is pretty high, except in compare to great Tube / Valves circuits

.. I will use my own precision 120 Volt Discrete Regulator

as this regulator has been posted already twice ( 2 times )
i need not post it here again

my readers will have it in their collection of good discrete regulated power supply schematics,
in the folder named: Lineup Circuits

basically uses one TL431 for good temp stabilty reference


Nice, revealing schematic Lineup.
You really like to keep us all in suspense, don't you?

Cheers,
Glen
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Old 29th August 2008, 02:14 AM   #13
KSTR is offline KSTR  Germany
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You really like to keep us all in suspense, don't you?

In German that's called "Salamitaktik"...

BTW, SoundPerformanceLab, a german based studio gear maker, have discrete op-amps in many of their products, using +-60V rails...

- Klaus
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Old 29th August 2008, 04:43 AM   #14
Bonsai is offline Bonsai  Taiwan
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Interesting discussion here about supply rails. In my discrete op-amp cct (in the 'real men dont use . . . ' thread), I also run with quite high rails - 25 to 35V either side of 0V. At +-15, distortion simulates at about 10ppm. If the rails are taken up to +-30 or 35V, the distorion drops to <1ppm.

Of course, academic issue at these levels, but I have not managedto work out why (BTW, I checked this with f/back - I have not checked the open loop situation).

Hmmm?

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Old 29th August 2008, 10:21 AM   #15
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Bonsai nice opamp.

Nelson Pass has mentioned the increase of supply voltage to increase performanse in his paper about opamps.

In my view it has not so much to do with the circuit but with the characteristics of the components eg trannies. Using transistors near their optimum operating specs have advantages. Have a look at datasheets eg. in the case of higher voltages look at how capacitances drop at higher voltages. Transistor theory will tell more. As with semiconductors im pretty sure their will be some downfalls too, thinking of noise.
Harmonic distortion content can even be manipulated to a more favourable or better say user or subjective preferred spectrum to a certain degree using diffirent trannies in a certain position or operating at different voltages, thats for those that are more subjective.

Glen could probably tell us more on this.
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Old 29th August 2008, 11:18 AM   #16
GK is offline GK  Australia
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Higher rail voltages for a given output voltage swing and transistor type gives you less distortion (particularly from the VAS) because the percentage of Vce variation is less.

You get less of Hawksford's "slope distortion".

Cheers,
Glen
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Old 29th August 2008, 02:25 PM   #17
Bonsai is offline Bonsai  Taiwan
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Homemodder - thnks

Glen - yes, this is one of the reasons I used a Hawsford VAS stage. I was hoping to be able to find another 1 or 2 places in the cct where I could take out a few more hundred ppb - but I could not find it despite a good few hours of work.
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Old 29th August 2008, 03:48 PM   #18
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lineup, the transistors you are planning to use have a maximum rating of 120V, and you are proposing a 120V supply rail.

This doesn't give a lot of safety margin for transients, voltage spikes and the like. Would it be more reliable if you dropped the supply rail to say 110V or even 100V?
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Old 29th August 2008, 03:56 PM   #19
lineup is offline lineup  Sweden
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the voltage gain in my prototype
will be
x 20 (= + 26 dB)

this is not in any way effected by if you use Feedback or No Feedback
the figure is all the same, to the decimal:
The output Voltage will be 20 times higher
than input voltage


the final testing is done at output level:
20 Volt RMS (= +- 28.3 Volt peak)
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Old 29th August 2008, 06:58 PM   #20
fotios is offline fotios  Greece
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Default 2sc2240 - 2sa970

I have used already these bjts in the improved version of my amplifier by substituting MPSA06-MPSA56 with these in small signal stages.
Great improvement. The rise time it is now 1,47žs instead with MPSAs was 1,9žs (under the same drive signal and load).
2N5551-2N5401 are real "factory workers". I have used them also in my high power (thus with supply rails up to +/-90Vdc) P.A. type amplifiers with success.
My place was - from the first, when i was registered in diyaudio forum - that the bigger the supply voltage level, the bigger the dynamic range the bigger the headroom, etc, etc, etc......
Lineup, he knows.

Fotios
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