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shadders
27 posts
Occasional Visitor
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16-02-2010 14:16
Hi,
I have been examining the Titan 2000 power amplifier (200w) in Build Your Own High End Audio Equipment book by Elektor.
The long tailed pair input consists if JFET's that are no longer available. The design is more than 10 years old, and the book does not specify the performance using the usual Audio Precision THD curve tracer.
Is it possible that the design could be revisited to improve, or provide the technical performance characteristics - such as power provided in 8ohm and 4ohm loads, as well as the THD curves ?.
Alternatively, i was willing to create the PCB's myself, but since the FET transistors are not available, can alternatives be suggested such as a dual FET device to ensure better component matching, or again a redesign of the amplifier to upgrade components that are now not available. Thanks.
Regards,
Richard.
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shadders
27 posts
Occasional Visitor
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02-03-2010 10:34
Hi,
I have been examining the Titan 2000 output stage, and i have a question with regards to the implementation of the output transistors.
The transistors are not set up in the usual emitter follower configuration. They are set up as follows :
Supply Rail (+63v) - 0.22ohm resistor - Emitter - Collector - Loudspeaker Output Terminal (neglecting other parts)
I understand that transistors are bipolar and the collector and emitter are interchangeable, hence
Q1. Why was this circuit designed in this way ?.
Q2. Can the circuit be redesigned as emitter followers with the 0.22ohms resistors placed in the emitter to loudspeaker connecton not changing any other component and without any impact on safety or performance ?
Q3. The book text indicates two of the three current gain transistors, hence is there information missing ?.
Q4. What is the damping factor of the amplifier for an 8ohm resistive load ?.
I would be graeful if the Elektor editorial could reply to these questions. Thanks.
Regards,
Richard.
Post edited by shadders
on 02-03-2010 10:36
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Elektor Editor
584 posts
Power User
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02-03-2010 15:54
Please specify title and page number and I'll be happy to forward the query to our audio department. The Titan 2000 is not included in the book you mention.
regards,
Jan
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shadders
27 posts
Occasional Visitor
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02-03-2010 16:21
Hi Jan,
Apologies - just checked - i thought the Titan 2000 was the 200Watt amplifier in this book, but is not. (Very red faced)
Hence the 200watt amplifier begins on page 87 of the book, and page 90 lists T23-T24, but not T31 the third output transistor for the positive supply.
Thank you very much for the reply.
Regards,
Richard.
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Mark63
33 posts
Occasional Visitor
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03-03-2010 09:19
Hi,
Elektor Electronics 2/99
>> admin
attachment removed -- copyright breach.
Post edited by Elektor Editor
on 03-03-2010 10:11
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shadders
27 posts
Occasional Visitor
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03-03-2010 10:14
Hi Mark,
Thanks. I have the CD-ROM which includes the document you posted. I made a mistake thinking that the book 200watt amplifier was the Titan. Thanks again for your help.
Regards,
Richard.
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Elektor Editor
584 posts
Power User
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03-03-2010 10:36
The book shows a beefed up version of the LFA-150 amplifier originally published in Elektor November 1988. This version has extra output transistors T 31 and T32 and runs off a slightly higher supply voltage (+/- 63V rather than +/- 56 V for the LFA-150).
The type numbers for T31 and T32 may be found in the bottom right hand corner of the circuit diagram.
This project being 20+ years old, we regret we no longer have the original design files to refer back to. I remember the LFA-150 was a blast at the time but sadly the source of the output transistors dried up.
Jan
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shadders
27 posts
Occasional Visitor
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03-03-2010 15:44
Hi Jan,
Thanks for the reply. The output transistors are available - Sanken manufacture them and they are available from Farnell.
WHat i originally was unsure about was the output transistors - seem to be in a collector-follower arrangement, with the output resistors in the emitter to +Vcc supply connection - with the PNP devices used in the positive cycle to conduct.
If i swapped the PNP devices with the NPN devices and vice versa, and used as emitter-follower with the output resistors between the emitter and loudspeaker connection - would this circuit still be safe and peform the same ?.
Thanks and Regards,
Richard.
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ATCONS
52 posts
Frequent Visitor
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02-01-2011 13:21
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ATCONS
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02-01-2011 13:40
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