Question for Patrick: if I have a PSU like Nelson Pass suggested in his F5T paper, with 40.000 uF connected to each rail after the R of the CRC, and that PSU is connected with 2.5 mm2 wires of 15 cm, would I still have to put 10,000 uF closer to the amp pcb? Or would the psu caps suffice?
I cannot tell, you have to try.
15cm should be OK, But I use HF litz wires.
https://www.ebay.de/itm/304154052959
Patrick
15cm should be OK, But I use HF litz wires.
https://www.ebay.de/itm/304154052959
Patrick
Hi,
Thanks Patrick for such a great project. I have had boards for a while, and about to build two pairs.
By any chance has anyone got any OPA604's that could sell me and ship to Australia? High voltage op amps seem to be unavailable at the moment!
Thanks in advance.
Cheers
Rob
Thanks Patrick for such a great project. I have had boards for a while, and about to build two pairs.
By any chance has anyone got any OPA604's that could sell me and ship to Australia? High voltage op amps seem to be unavailable at the moment!
Thanks in advance.
Cheers
Rob
You don't need the servo.
Build the amp without first.
Can always add later.
Patrick
Build the amp without first.
Can always add later.
Patrick
G'Day Patrick,
Sorry another question if I may, When matching Q2 and Q3 2sk209's (4 per channel), does it matter even if each side is matched, the VGS @ 3mA is different on each channel?
Cheers
Rob
Sorry another question if I may, When matching Q2 and Q3 2sk209's (4 per channel), does it matter even if each side is matched, the VGS @ 3mA is different on each channel?
Cheers
Rob
FQA9P25 is a P-channel MOSFET. All those you mentioned are N-MOSFETs.
To use those, build the J2 at the Pass forum, not this here.
And I do not think I used the KSC1845 anywhere in this circuit.
Are you sure you are in the right thread ?
Patrick
To use those, build the J2 at the Pass forum, not this here.
And I do not think I used the KSC1845 anywhere in this circuit.
Are you sure you are in the right thread ?
Patrick
I am sorry that I mixed up P-channel MOSFET and N-channel. In this post you are sharing a LTSpice scheme. https://www.diyaudio.com/community/...t-need-semisouths.343164/page-17#post-6655510
In this scheme is also Q1 - KSC1845.
If I like to use 2SJ618 or 2SJ201 then what changes are needed in this scheme and in this following scheme? https://www.diyaudio.com/community/threads/udness-or-you-dont-need-semisouths.343164/post-6832584
Have anybody tested this scheme and have built it amp?
In this scheme is also Q1 - KSC1845.
If I like to use 2SJ618 or 2SJ201 then what changes are needed in this scheme and in this following scheme? https://www.diyaudio.com/community/threads/udness-or-you-dont-need-semisouths.343164/post-6832584
Have anybody tested this scheme and have built it amp?
KSC1845 is an active device with plenty of voltage headroom.
Very easy to get. So why replace ?
They are both obsolete devices, so I shall not spend any time figuring out how to apply them here.
It is not what this circuit is meant for,
And I will certainly not publish any unproven schematics using them.
You are of course most welcome to run your own simulation using those devices.
In real life, you need to apply thermal compensation for the large positive tempco of the 2SJ618.
In addition, you need to change the values of the source resistors and the gate biasing resistor because of different Vgs ad Yfs.
Success,
Patrick
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And for anyone interested in this, the FQA9P25 is end of life, but still available at Mouser (>11000 pcs in stock).
So time to get lifetime stock.
Patrick
So time to get lifetime stock.
Patrick
KSC1845 is in my opinion a little bit noisy and there are maybe better replacements for using in audio circuit? I read that BC550 is also good to use. What are your thoughts about that? Do I need to change some resistors to use BC550?
Well, the BC550 is a transistor, which surely is an active part. In contrast, for example, resistors are passive parts. Maybe you meant to say that BC550 is not produced anymore, but there are still plenty of these parts around.
Active at Mouser / DK means that it is not obsolete.
Now clear ?
Again, UDNeSS was designed not to use ANY obsolete parts.
It does not matter what you can still get from ebay or diy store or what not.
Everything posted in this circuit, you can get from Mouser / DK with no NOS premium.
Patrick
Now clear ?
Again, UDNeSS was designed not to use ANY obsolete parts.
It does not matter what you can still get from ebay or diy store or what not.
Everything posted in this circuit, you can get from Mouser / DK with no NOS premium.
Patrick
G'Day from Australia!
When matching mosfets of the UDNESS @ 1.4A how close do you get the Vgs?
Thanks in advance
Rob
When matching mosfets of the UDNESS @ 1.4A how close do you get the Vgs?
Thanks in advance
Rob
Circuit still works without matching.
So it depends on how well you want equal current sharing, and channel matching.
If I have enough devices, then 3mV Vgs.
So let's say 10mV.
But you need a large pool to match from.
Patrick
So it depends on how well you want equal current sharing, and channel matching.
If I have enough devices, then 3mV Vgs.
So let's say 10mV.
But you need a large pool to match from.
Patrick