Hi word,
Schematic attached represents my first full discrete high power headamp (for mine 32 and 300R headphones), also I would like to use it as a small power amp during summer (already have a Class A SE mosfet amp for speakers, but it's way to hot to live with during summer). I want to know if there is something wrong with design, particularly if there is a better way to apply compensation. Power supply will be fully regulated and separated for input stage (few more volts then 24V shown) and triple EF buffer. Mind you, I am not an EE, I just keep an aye and take notes from big boys around this forum, so be nice, thank you!
Schematic attached represents my first full discrete high power headamp (for mine 32 and 300R headphones), also I would like to use it as a small power amp during summer (already have a Class A SE mosfet amp for speakers, but it's way to hot to live with during summer). I want to know if there is something wrong with design, particularly if there is a better way to apply compensation. Power supply will be fully regulated and separated for input stage (few more volts then 24V shown) and triple EF buffer. Mind you, I am not an EE, I just keep an aye and take notes from big boys around this forum, so be nice, thank you!
Hi TzeYang,
Thanks for replay...first image 1kHz step response just before clipping occurs driving 32 Ohms.
Thanks for replay...first image 1kHz step response just before clipping occurs driving 32 Ohms.
Hi,
does the current from D3 defeat the current mirror?
C1 looks a bit small, unless you have a very high source impedance.
What's the dissipation in each of Q17 & Q18?
does the current from D3 defeat the current mirror?
C1 looks a bit small, unless you have a very high source impedance.
What's the dissipation in each of Q17 & Q18?
AndrewT said:
Hi Andrew,
Thanks for replay,...yes it does, but distortion without cascade are 30db higher (second harmonic)
AndrewT said:
Should I put something like 100pF instad?
AndrewT said:
It's about 220mW, a bit high for TO-92, but I would eventually put small heatsinks on them.
can the mirror cascode be applied outside the mirror voltage sensors?aparatusonitus said:
1k0 and cap ranging between 330pF and 1nF would be more effective.
4.6mA in the drivers seems a bit light for a 32ohm ClassA output stage.
AndrewT said:
Probably yes, but I've not tryed that...but I will try that and report back.
AndrewT said:
Ok, thank you.
AndrewT said:
But standing current is twice as that?
9.2mA and 48V plus the base current feeding the outputs, all from a bc547.aparatusonitus said:
you are joking, aren't you?
Ah, I see now thank you, so I will change Q17/18 for TO-126 devices (BD139/140) and ouput Q's for TO-220 (MJ15030/15031). How much current you would suggest for each buffer driver stage to stay in class A for 32 phones for full dynamic range?
The 4pair of BDs may make a good output stage.
It's just the To92 drivers I'm concerned about.
Some fast, high gain, 5W To126 drivers would probably be more suitable
It's just the To92 drivers I'm concerned about.
Some fast, high gain, 5W To126 drivers would probably be more suitable
beautiful headamp. I'm trying out something similar but with a totally different VAS stage.
Do you mind posting the open loop gain of the amplifier?
Do you mind posting the open loop gain of the amplifier?
AndrewT said:
If I connect a LED's string from PSU rails (3 psc. from +24V, 2 pcs. from -24V) and keep the same static for entire amp, THD looks like this for light load of 600R and 1Vpp output...
...for as per original sch THD looks like this
...it's like 30dB improvement for H2/H3 so I would really like to know why...or is it just sim playing with me as usual?
- Status
- Not open for further replies.