A few people sent PMs asking for Bill of Materials for the circuits.
Firstly I have, as an exception, already posted component values in the schematics.
But they should be treated as provisional, and will only be finalised after we have completed all build and tests ourselves.
This will help us and you, to avoid confusions due to multiple revisions.
From our experience from the F5X and the Joachim Gerhard projects, we have also decided only to publish final schematics and BoM at our own website.
This will allow us full flexibility for Version control and editing.
So I can only ask you to kindly bear with us for now.
When we are ready to publish them, we shall put up announcements here.
Thank you for your interest,
Patrick
Firstly I have, as an exception, already posted component values in the schematics.
But they should be treated as provisional, and will only be finalised after we have completed all build and tests ourselves.
This will help us and you, to avoid confusions due to multiple revisions.
From our experience from the F5X and the Joachim Gerhard projects, we have also decided only to publish final schematics and BoM at our own website.
This will allow us full flexibility for Version control and editing.
So I can only ask you to kindly bear with us for now.
When we are ready to publish them, we shall put up announcements here.
Thank you for your interest,
Patrick
Some test results :
Current configuration is DAO standard, bias 195mA.
10kHz square wave with 56R load is perfect without any overshoot.
Gain is 0.876, in line with expectation (Load = 56R, Zout = 7.8R, of which 6.8R is pure resistive.).
DC offset 4mV.
Also as expected some load is required for stability.
For headphones with high impedance, especially at HF, a Zobel of 27R 10nF will ensure perfect response.
Next steps would be to add TCs and HAGS module.
Patrick
.
Current configuration is DAO standard, bias 195mA.
10kHz square wave with 56R load is perfect without any overshoot.
Gain is 0.876, in line with expectation (Load = 56R, Zout = 7.8R, of which 6.8R is pure resistive.).
DC offset 4mV.
Also as expected some load is required for stability.
For headphones with high impedance, especially at HF, a Zobel of 27R 10nF will ensure perfect response.
Next steps would be to add TCs and HAGS module.
Patrick
.
Attachments
Took a bit longer than I wanted, but HAGS is finally tested.
Without any trimming, initial DC was 160mV.
After one trimming resistor (calculated value), DC was down to less than 4mV at steady state.
Cold start value was about 15mV, but this settles to near zero after 3 minutes.
Bear in mind that the DAO following the HAGS is unity gain, and 10mV is 1.5µW for a 65R headphone, I do not consider servo necessary.
Attached also square wave response for 10kHz and 100kHz, as well as frequency response to 2MHz.
-3dB is at about 1MHz. So performance meets expectation.
(Green is input, cyan output.)
🙂
Patrick
Without any trimming, initial DC was 160mV.
After one trimming resistor (calculated value), DC was down to less than 4mV at steady state.
Cold start value was about 15mV, but this settles to near zero after 3 minutes.
Bear in mind that the DAO following the HAGS is unity gain, and 10mV is 1.5µW for a 65R headphone, I do not consider servo necessary.
Attached also square wave response for 10kHz and 100kHz, as well as frequency response to 2MHz.
-3dB is at about 1MHz. So performance meets expectation.
(Green is input, cyan output.)
🙂
Patrick
Attachments
Very nice performance. Indeed, the offset is small enough not to need a servo, as long as it does not drift, and I expect you have paid your usual attention to the thermal design so that it does not drift.
Hi Patrick, just beeing patient and keeping a very keen eye out.
Just a query - on post #64 back in Feb, you mentioned that you were using the "Standard DAO" at 195mA - Is this the previous non-Taylored version with the IRFP fets or is this pushing the smaller 2sk/j units well above the 100mA detailed in the design sheets?
Just a query - on post #64 back in Feb, you mentioned that you were using the "Standard DAO" at 195mA - Is this the previous non-Taylored version with the IRFP fets or is this pushing the smaller 2sk/j units well above the 100mA detailed in the design sheets?
The 2SK2013 is a TO220 device and fully capable of 200mA or more in Class A.
The very original schematics I published years ago uses a 2SK1529 at ~330mA bias.
Patrick
The very original schematics I published years ago uses a 2SK1529 at ~330mA bias.
Patrick
Time to publish Part 4 & 5.
Next on the to do list is to test the new TCS circuit.
Needs to get new PCBs made first.
Patrick
Next on the to do list is to test the new TCS circuit.
Needs to get new PCBs made first.
Patrick
Like all of us, this is hobby for me and I happen to have a busy day-time job as well.
Hope it is understandable.
Patrick
Hope it is understandable.
Patrick