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Old 16th August 2011, 01:28 PM   #51
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Quote:
Originally Posted by ingenieus View Post
Thank you for this information.
A similare topology I have found in the magazine "Audio Amateur" 3/96 (THREE: 1996), start from page 22:
"10 Watt Class-A" by Dick Crawford.
Equipped with a dual OP-Amp "LT1124", one pair MOSFET IRFP150/RFH25P08 and an active bias part. Actually not exact matched for this topic, but through the great similarity in the circuit topology I mentioned here.
Perhaps one of the member can scan and upload this article.

Last edited by tiefbassuebertr; 16th August 2011 at 01:34 PM.
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Old 21st August 2011, 08:02 PM   #52
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Originally Posted by lineup View Post
Nice to see you use NE5534 (compensated) and not NE5532.
Because NE5534 is the better one.
And ridiculously lowcost vs. performance.
Hello there.
What is better ?
It seems to me NE5532 is the same as NE5534 with a 20pf compensate capacitor.
This based from Texas Instrument data sheets and contents of Spice model files.
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Old 22nd August 2011, 02:54 PM   #53
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An external capacitor gives you a lot more scope. Just for that freedom of choice that I would vote for the NE5534.

If you look at the internal circuits, they are very similar but there are a few small differences between them.
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File Type: jpeg ne5534.jpeg (94.1 KB, 536 views)
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Old 23rd August 2011, 11:29 PM   #54
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Thanks Ingenues, I am working on a similar design.
I started working with OPA134 then I consider NE553x because of it's +-22volt power supply ability.
With LTspice simulation with NE5534 I can see what happens about the compensation capacitor value about a design of mine close to the one published in this thread.
0pF unstable
10pF unstable
15pF marginaly stable THD 0.0025% @ 20Khz
20pF stable THD 0.003% @ 20Khz
30pF stable THD 0.007%
40pF stable THD 0.015%
60pF stable THD 0.05%
Clearly a THD / stability trade off.

Where can I find NE5534 diagrams giving Gain versus Frequency and Phase versus Frequency at various Cc values ?
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Old 23rd August 2011, 11:33 PM   #55
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Originally Posted by mchambin View Post
Where can I find NE5534 diagrams giving Gain versus Frequency and Phase versus Frequency at various Cc values ?
The there is a bandwidth product that you use.
Bandwidth/ gain = maximum frequency.
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Old 24th August 2011, 12:35 AM   #56
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Originally Posted by nigelwright7557 View Post
The there is a bandwidth product that you use.
Bandwidth/ gain = maximum frequency.
I'd like Bode diagrams to study about stability. To find Phase margin and gain margin.
The Gain Bandwith product ( 10 Mhz for the NE553x ) is not the answer about stability margin.
The TI datasheets, I found are giving Gain versus Frequency but no Phase versus Frequency. Both are needed to find stability margin.
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Old 19th January 2012, 03:02 AM   #57
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Looking for higher voltage op amps
OPA551 is +- 30v 200mA ( it's not +-40v as stated in #1 )
OPA604 is +- 24v
Are they other affordable "high" voltage op amps ?
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Old 19th January 2012, 09:11 AM   #58
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LME49810 etc.
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Old 13th December 2012, 01:02 PM   #59
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Modeling software tells only half truth, another half will be known once the whole thing is built. Nice design, worth trying. The op amp can be replaced with almost any op amp right?
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Old 13th December 2012, 01:29 PM   #60
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Quote:
Originally Posted by ingenieus View Post
An external capacitor gives you a lot more scope. Just for that freedom of choice that I would vote for the NE5534.

If you look at the internal circuits, they are very similar but there are a few small differences between them.
Would be more accurate to compare them within a single manufacturer.
The first sch is from TI and the second one from Phillips and it s likely
that they use these schematics even for the other variant.
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