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Old 3rd November 2013, 06:46 PM   #101
borys is offline borys  Poland
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Ok I will put BC550/560 thanks.
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Old 4th November 2013, 06:13 AM   #102
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Originally Posted by borys View Post
Next step is as mr Mile advised stabilised psu for front end, next prapobly cascaded vas (here I may need some help).
You can simple stabilised psu for front end just add zeners in parallel with C4 and C5 and recalculated resistors value.
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Old 4th November 2013, 06:41 AM   #103
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Very nice. For line level voltages when high gain transistors are available might get away without this level of complexity ? As an ongoing research SYMEF has been claimed to sound much better than LM3886 so far Thanks for posting.

kind regards,

Harrison.

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Originally Posted by ChocoHolic View Post
Keep on going this project.
My comment is just about the naming.

From my perspective this thread is showing only one schematic with a diamond topology and this was the Non Differential Elektor Diamond.
Attached a principal sketch of an input configuration which I would link to the title of thread.
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Old 4th November 2013, 07:00 AM   #104
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Quote:
Originally Posted by OnAudio View Post
Very nice. For line level voltages when high gain transistors are available might get away without this level of complexity ? As an ongoing research SYMEF has been claimed to sound much better than LM3886 so far Thanks for posting.

kind regards,

Harrison.
HD50 with +/-50V rail and 2 pair of outputs is without casscodes, but HD150 with +/-75V 4 pairs and HD300 with +/-95V rail and 6 pair of outputs must use cascode in diamond drive and vas.
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Old 4th November 2013, 07:52 AM   #105
borys is offline borys  Poland
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I putted the cascade (added bc546/556 for now) and it looks ok so far. I have some work left to do anyway. Amp will be playing whole day at work.
I have putte 470R resistors in front 2 amplifiers (mayby bit too big value). Amp is bit slower but stable.
The overshoot at 1kHz at one of scope reading is with 0,47uF parallel with 8R.

apexaudio
I have few questions:
1. front stage - use the capactance multiplier psu + resistor as current source or better use ccs instead of resistor (with capactance multiplier psu) ?
2. second stage of differential amps - the max Uce voltage while clipping is around 28V (+/-45V psu) so I can use bc550/560 paris too ?
3. I am going to try fets in front stage - do I have to change a circuit a lot ? (in some amps I was just soldering j-fet instead od bjt and all looked ok)

thanks
Attached Images
File Type: png 1kHz.png (59.1 KB, 406 views)
File Type: png intermod.png (54.1 KB, 397 views)
File Type: jpg hd1.jpg (62.7 KB, 377 views)
File Type: jpg hd2.jpg (66.1 KB, 367 views)
File Type: jpg hd4.jpg (61.5 KB, 356 views)
File Type: jpg hd5.jpg (66.4 KB, 34 views)
File Type: jpg hd6.jpg (62.5 KB, 32 views)

Last edited by borys; 4th November 2013 at 08:00 AM.
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Old 4th November 2013, 10:09 AM   #106
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Quote:
Originally Posted by borys View Post
I putted the cascade (added bc546/556 for now) and it looks ok so far. I have some work left to do anyway. Amp will be playing whole day at work.
I have putte 470R resistors in front 2 amplifiers (mayby bit too big value). Amp is bit slower but stable.
The overshoot at 1kHz at one of scope reading is with 0,47uF parallel with 8R.

apexaudio
I have few questions:
1. front stage - use the capactance multiplier psu + resistor as current source or better use ccs instead of resistor (with capactance multiplier psu) ?
2. second stage of differential amps - the max Uce voltage while clipping is around 28V (+/-45V psu) so I can use bc550/560 paris too ?
3. I am going to try fets in front stage - do I have to change a circuit a lot ? (in some amps I was just soldering j-fet instead od bjt and all looked ok)

thanks
1. use ccs and zener + resistor or ccs as current source, post #68
2. second stage or diamond drive DD can use bc550/560, use hawksford cascode circuit from SR200 in vas for higher cliping level
3. use Sansui circuit for single n fet front end, post #54
Regards

Last edited by apexaudio; 4th November 2013 at 10:24 AM.
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Old 4th November 2013, 08:43 PM   #107
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Quote:
Originally Posted by borys View Post
...
The overshoot at 1kHz at one of scope reading is with 0,47uF parallel with 8R.
Is the green trace the negative supply voltage? If it is, where is the scope connected, close to the output transistors, close to the power supply...?
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Old 4th November 2013, 08:53 PM   #108
borys is offline borys  Poland
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PMI
The green supply voltage is connected after fuse and thin wire (maybe here is the bug). I have to prepare nice board and test again.
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Old 4th November 2013, 10:05 PM   #109
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Quote:
Originally Posted by borys View Post
PMI
The green supply voltage is connected after fuse and thin wire (maybe here is the bug). I have to prepare nice board and test again.
Those excursions on the green trace that I see are huge. They look like 10V pk-to-pk... If those are real, whether on the ground bus or on the rails, it will affect the rest of your readings.
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Old 4th November 2013, 10:43 PM   #110
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Quote:
Originally Posted by borys View Post
PMI
The green supply voltage is connected after fuse and thin wire (maybe here is the bug). I have to prepare nice board and test again.
With respect, I don't think so. I repeated one of my tests with a 6ft extra wire in the connection from the amplifier board to the positive supply terminal. Note the vertical scale of the second trace. That oscilloscope channel is set to 2V/division.

What you can see is the effect of a bit of added resistance from the wire, about 100~150 millivolts when power is drawn from that rail. No spikes or ringing on the supply at all, and I am not known for neatness when it comes to arranging test leads...
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