A Zen Split Load Amp

[happyrabbit]

Hammond 196Q2 vs 159ZJ

https://www.hammfg.com/files/parts/pdf/159ZJ.pdf
https://www.hammfg.com/files/parts/pdf/196Q2.pdf

~4.5w @ 7r. Both setups were operating - 15v @ 2a. The upper freq noise is from the power op amp rail to rail leveler shifter. The negative and positive charge pumps are not well filtered. see attached pic for the output noise. Plus the open loops gain isn’t the best.. the 60hz spike is lovely. I am working on discrete voltage regulator for the next PCB. The power op amp helps dampen inductor but limits the 2nd order harmonics.. not the triode profile I was hoping for ! The parallel inductor thd% is ~50% less than the 2 single inductors.

dwight

 

[happyrabbit]

here is the next pcb. A bit different. No more power op amp for the dc supply. The new dc supply will be based on a Sparkoslabs op amp and a to-264 npn bipolar. Also I will be using (1) TO-264 Exicon instead of (2) TO-247. The main current loop is much tighter plus low level stuff is now located on outside. I have also ordered a pair of Jupiter silver foil caps . they are pricey but curious to see how they sound. See attached

 

[happyrabbit]

Done.. I will post the FFT in the near future. See attached. It powered up. Performed a quick check with a volt meter and started listening.

dwight

 

[happyrabbit]

4.5w @ 7r

 

[happyrabbit]

Here is an updated fft. Much more set like ! needed to turn the current up to 2.7a. 4.5w @ 7r.

 

[adason]

Could somebody please fix the thread title?

 

[Mooly]

Fixed 🙂

 

[happyrabbit]

Finished the other channel. It’s impressive.

 

[happyrabbit]

with the covers on..

 

[happyrabbit]

Update.. Added a dc servo for the bias current. The exicon wandered too much @ various room temperatures. I selected the low pass filter (1ohm) used to clean up the noise before the voltage regulator as the current shunt. There is a bit current ripple @ 60hz plus harmonics. Maybe not the best choice on my part… I added a 100r/100uf after the differential to se op amp to knock the noise down even further. ignore the 1khz harmonics on the dc servo bias fft (last fft). See attached. opa196 for the diff to se. ada4422 for the inverting sc servo. Current stabilizes @ ~5S (1m/1uf). a very nice addition to have. not prefect but just as quite as the passive bias pcb using 99db speakers.