Replaced C2 with 10uF (can I leave X7R there or is it much better to reorder the original Panasonic - you had it there for a reason I suppose) for the time being and inserted 5k trimmer (this is what I had in my drawer, I had 10k originally but it was not multiturn, this thing is very delicate so I wanted to use multiturn after all)
I can now turn on the output stage and control the current.
I have set it up at 160mA, I see 35mV offset at the output. (my build does not have servo yet- hopefully never; I forgot to remove servo from the LSpice simulation - for a moment I could not reconcile spice with my build...)
I can now turn on the output stage and control the current.
I have set it up at 160mA, I see 35mV offset at the output. (my build does not have servo yet- hopefully never; I forgot to remove servo from the LSpice simulation - for a moment I could not reconcile spice with my build...)
I am pretty sure Patrick has already given up on me regarding SLHPA.
I bought PCBs from Patrick before Covid. To my excuse I can say that the DigiKey parcel with all component arrived at my office one day after I started working from home in the first lockdown.
Meanwhile I have built UTHAiM so I kept myself busy and less motivated given how nice UTHAiM.
Anyway here it is (one problem - I've blown the protection circuit in the final assembly - I connected the power supply to the protection circuit in reverse - I was very careful during the whole build, checked and rechecked everything, bought a dual lab PS with current limit to test (it saved my life a few times) and then it takes just one brain fart and puff - I guess the op amp is gone and maybe other things)
So, no protection for some time. The offset in one channel is 2-4mV and 10-12mV in the other (I need to look at this channel again, but I can live with 10-12mV offset for now).
(please do not comment on the volume knob - can't remember where I put the one I actually want to use).
I replaced the alu front panel with the wooden one - it was meant to be a prototype before I drill the one supplied with the chassis. But in fact I like it this way.
I bought PCBs from Patrick before Covid. To my excuse I can say that the DigiKey parcel with all component arrived at my office one day after I started working from home in the first lockdown.
Meanwhile I have built UTHAiM so I kept myself busy and less motivated given how nice UTHAiM.
Anyway here it is (one problem - I've blown the protection circuit in the final assembly - I connected the power supply to the protection circuit in reverse - I was very careful during the whole build, checked and rechecked everything, bought a dual lab PS with current limit to test (it saved my life a few times) and then it takes just one brain fart and puff - I guess the op amp is gone and maybe other things)
So, no protection for some time. The offset in one channel is 2-4mV and 10-12mV in the other (I need to look at this channel again, but I can live with 10-12mV offset for now).
(please do not comment on the volume knob - can't remember where I put the one I actually want to use).
I replaced the alu front panel with the wooden one - it was meant to be a prototype before I drill the one supplied with the chassis. But in fact I like it this way.
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Regarding SLHPA and UTHAiM they sound similar and great. In my case probably the diff comes from different xfeed in each of them. I like they xfeed with values in the SLHPA doc so I will make a copy for UTHAiM and compare more. Also SLHPA is dual mono with Patrick's regulators. My UTHAiM has one transformer and dual PSs down the line with capacitance multipliers.
Did I say SLHPA sounds great? Yes it does! Thanks Patrick!
Did I say SLHPA sounds great? Yes it does! Thanks Patrick!
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I am sure you can improve the wiring. 
See photos of my build.
For temporary protection, just use an output coupling cap.
e.g. Panasonic ECE-A1EN102U // WIMA MKS2 10µ
As to sound, the UTHAiM has a lot of power reserve.
It can easily drive 8-ohm speakers, especially with a bit of negative feedback.
The SL is a bit more polite but refined, I would say.
It is my reference when I want to test a player, for example.
I am normally a FET man, but the SL really has something.
For me at least, the King is still the DAO.
https://www.diyaudio.com/community/...a-zgf-headphone-amplifier.225577/post-7325913
It is though a difficult and involved project. Only for capable DIYers.
Patrick
See photos of my build.
For temporary protection, just use an output coupling cap.
e.g. Panasonic ECE-A1EN102U // WIMA MKS2 10µ
As to sound, the UTHAiM has a lot of power reserve.
It can easily drive 8-ohm speakers, especially with a bit of negative feedback.
The SL is a bit more polite but refined, I would say.
It is my reference when I want to test a player, for example.
I am normally a FET man, but the SL really has something.
For me at least, the King is still the DAO.
https://www.diyaudio.com/community/...a-zgf-headphone-amplifier.225577/post-7325913
It is though a difficult and involved project. Only for capable DIYers.
Patrick
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I am not happy with the wiring myself, but I am struggling as too short wires make it difficult to assemble disassemble in the early stages.
Also I see that your motherboard has lots of paths which make wiring easier or redundant.
I know DAO is the King, I studied it but I think it is too complicated for me. I feel intimidated by other builds too (shall I mention Stixx here?).
SLHPA was my first extensively SMD project. I have learned a lot especially after I followed your advice to get thin soldering wire and a sharp tip for the soldering iron.
Also I see that your motherboard has lots of paths which make wiring easier or redundant.
I know DAO is the King, I studied it but I think it is too complicated for me. I feel intimidated by other builds too (shall I mention Stixx here?).
SLHPA was my first extensively SMD project. I have learned a lot especially after I followed your advice to get thin soldering wire and a sharp tip for the soldering iron.
Some people swear on bipolar amps. Some on FET.
You can make good amps with both.
I know a lot more about FETs, and you can make real simple ones.
See how complex the SL is compared to say a F5-HA.
But we shall hopefully soon publish a pocket size headphone amp which is only bipolar based.
That is made necessary by the low voltage, but it is in some ways simpler than the SL.
Patrick
You can make good amps with both.
I know a lot more about FETs, and you can make real simple ones.
See how complex the SL is compared to say a F5-HA.
But we shall hopefully soon publish a pocket size headphone amp which is only bipolar based.
That is made necessary by the low voltage, but it is in some ways simpler than the SL.
Patrick
https://www.diyaudio.com/community/threads/the-pioneer-super-linear-circuit.313163/post-5213484
This is the challenge.
Patrick
This is the challenge.
Patrick
If we are successful with a GB4, we'll let you have our then last SHPP PCB at cost.
https://www.diyaudio.com/community/...ar-headphone-amp-pcb-set.399425/#post-7353642
Patrick
https://www.diyaudio.com/community/...ar-headphone-amp-pcb-set.399425/#post-7353642
Patrick