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Old 30th March 2014, 08:51 PM   #1
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Default 6AQ5 excellent for line stage?

Anybody test 6AQ5 for line stage?
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Old 30th March 2014, 09:23 PM   #2
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At one time I was intrigued by the SRPP "Mobius". I'd still like to try something like this, maybe as a mu-follower instead.

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Old 31st March 2014, 03:37 PM   #3
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Quote:
Originally Posted by matejsirk View Post
Anybody test 6AQ5 for line stage?
Is the load impedance you used with simulation (470k) quite impractical ?

I just noticed that modern active subwoofers (Yamaha YST-) have as low as 12 kohms input impedance.
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Old 1st April 2014, 02:09 AM   #4
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Quote:
Originally Posted by artosalo View Post
Is the load impedance you used with simulation (470k) quite impractical ?

I just noticed that modern active subwoofers (Yamaha YST-) have as low as 12 kohms input impedance.
The 470K ressitor is simply a DC ground return, not an actual load.

I've used 6AQ5s as series pass devices in active regulators, but these should have good sonic performance as well.
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Old 1st April 2014, 06:22 AM   #5
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Quote:
Originally Posted by Miles Prower View Post
The 470K ressitor is simply a DC ground return, not an actual load...
The schematic matejsirk presented is a LTspice schematic (.asc).
Therefore I have thought that he obviously had used that to simulate the performance of the circuit.
Did you notice the THD reading 0,000658 % with 4 Vpp there ?
I doubt it is not reality with actual loads, like 12 kohms.
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Old 1st April 2014, 07:52 AM   #6
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Quote:
Originally Posted by artosalo View Post
The schematic matejsirk presented is a LTspice schematic (.asc).
Therefore I have thought that he obviously had used that to simulate the performance of the circuit.
Did you notice the THD reading 0,000658 % with 4 Vpp there ?
I doubt it is not reality with actual loads, like 12 kohms.
The simm does look unrealistically optimistic. It's possible he used a no load condition for that. The SRPP will balance for three load conditions: dead short (turns both sections into grounded cathode amps) no load (just one current path: through both tubes) and the specific load resistance where source current equals sink current. Otherwise, the source and sink currents go out of balance, and distortion rises.
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Old 1st April 2014, 08:43 AM   #7
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A dead short will not necessarily balance the SRPP.
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Old 1st April 2014, 01:22 PM   #8
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Quote:
Originally Posted by artosalo View Post
The schematic matejsirk presented is a LTspice schematic (.asc).
Therefore I have thought that he obviously had used that to simulate the performance of the circuit.
Did you notice the THD reading 0,000658 % with 4 Vpp there ?
I doubt it is not reality with actual loads, like 12 kohms.
You're right. I'm not simulate the 12K. I will tonight.
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