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Old 12th September 2002, 08:39 AM   #16
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Mr. Pass

Tanks for the answer.

But there is still a question that bothers me: I assume that the decision about the feedback takeoff point was made due to measurement AND listening tests and that several versions have been tried (am I right ?).
Did both correlate or was the feedback takeoff at the output sonically inferior but superior from the measurement point of view ?

Regards

Charles
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Old 12th September 2002, 07:40 PM   #17
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The amps measured about the same both ways, so the
decision was from a sonic and marketing basis.

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Old 9th January 2003, 08:01 AM   #18
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Default Stasis Schematic - Not Viewable

My repeated attempts to download the Stasis schematics and view them have failed. After the download is complete, attempting to open the file gives an error relating to some Kodak...

I have tried to open the file with MS PhotoEditor, Ulead Photoimpact etc., but to no avail.

Can someone please help with some tips or send a copy through email? Thanks in advance.
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Old 9th January 2003, 08:36 AM   #19
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Default Re: Stasis Schematic - Not Viewable

Quote:
Originally posted by Samuel Jayaraj
Can someone please help
shrunk, tweaked, & attached

dave
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File Type: gif stasis2-3schem.gif (30.5 KB, 2747 views)
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Old 11th January 2003, 07:00 AM   #20
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Dave, thank you very much for posting the schematic of the Stasis amp.

I have a few questions about the schematic. I know that Nelson is busy at CES, so I don't really expect answers from him. But anyone else...?

The Vbe multiplier is shown as A42. I presume this is an MPSA42. I wonder how the TO92 package is coupled to the heatsink for thermal tracking. There is an unmarked resistor between the Vbe emmiter and output track. What could be its likely value? A meter like diagram is shon in shunt with the 100E resistor in the bias circuit. What could this indicate?

The transistor types are now shown from the driver stage to output stage. Any ideas? The output devices are loaded with resistors which have marking such as 1(.68), 1.5(.3) etc., Does this mean 1E, 1E5 resistors and the numbers in parenthesis the voltage drop.

A thermal braker is indicated in the CCS of the first stage. Where does this connect?

Finally, can modern devices replace the ones originally used. That is the rail voltage, output power and 2ohm capability of this amp?

I ask because I want to compare this with the Leach Amp which I have decided to build as 2ohm capable, in order to drive 2x18" hornloaded paralleled woofers at 1200 watts (4ohms) ie., Bridged Leach Amps.
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Old 28th November 2003, 02:38 PM   #21
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Default stasis II bias

I have a Stasis II and am concerned about the fact that the VBE transistors are in fact MPSA 6571 on both channels (vce 20 w).
I do not know wether the've been seviced with a replacement or built that way; Are the MPSA 42 the original parts as on the drawings?
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Old 28th November 2003, 06:34 PM   #22
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Sam,

I have two Stasis 3's sitting in front of me. The Vbe multiplier is not attached to the heatsink. The thermal breaker is attached to the heatsink. If you look at the diagram you will find that the resistor is 4.7k. The unknown device is a thermister.

Regards,
Jam

P.S. If photographs are required I may be able to provide them next week.
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Old 28th November 2003, 07:03 PM   #23
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Quote:
Originally posted by Samuel Jayaraj
--snip--
The transistor types are now shown from the driver stage to output stage. Any ideas? The output devices are loaded with resistors which have marking such as 1(.68), 1.5(.3) etc., Does this mean 1E, 1E5 resistors and the numbers in parenthesis the voltage drop.
--snip--
[/COLOR]
Reading the schematic it says that values are for Stasis 2 and the values in parantesis is for Stasis 3.
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Old 28th November 2003, 07:19 PM   #24
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The Statis 2/3 drawing is beautifully inked and lettered. I wish we could get decent output from modern CAD schematic capture.
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Old 29th November 2003, 06:39 AM   #25
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Well, the gentleman who did those , Kirk Rader, is dead. But
now his name lives on forever on the Internet!

(Don't ever say I didn't do you a favor, Kirk.)

He came to Threshold from Audio Research, and so if you ever
get hold of some older AR schematics you might note a
resemblance (except for the tube parts).

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Old 29th November 2003, 11:29 AM   #26
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thank you mr nelson pass, now i can have a closer look at your amps, whereas many years back i can only look at them from the pages of the Audio Magazine, wondering what circuit topology you used....

you are God's gift the the audio industry and diyaudio.com is God's gift to DIY'ers like me....
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Old 29th November 2003, 01:30 PM   #27
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One trick that works in getting a schematic to look like that is to draw it by hand, but at 2X scale. Then photograph it and reduce to 1X. All the little jiggly places drop out of sight and leave behind an elegant looking drawing. Should be easy with a digital camera and all the fancy photo manipulation software available today.
I run across old drafting books at book sales for a dollar or two that show the conventions used, but someone with an eye for detail can pick up the right tricks just by looking over a lot of old, hand-drawn schematics.
It still helps to have a steady hand.

Grey
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Old 29th November 2003, 03:50 PM   #28
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Can somebody please inform what the component I have marked is ???
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File Type: gif stasis2-3schem_quest.gif (32.0 KB, 1586 views)
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Old 29th November 2003, 04:03 PM   #29
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Thermistor 1K?

/Hugo
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Old 29th November 2003, 05:57 PM   #30
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Thanks netlist
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