Thanks friends!
I prepared aluminum faceplate (3" X 13", 6mm thick). I sprayed it chrome spray paint used for car alloy wheels. This is supposed stick to Aluminum. But waiting for com-paint lacquer (clear coat) to arrive as it will give some protection and shine to that color. I will post some pics after that.
Here are my (Musical and Electrical) impressions of this build.
PASS B1:
No turn on/off pop. Just start music with attaining max volume within 5 sec. Large capacitors took 1 minute from power on to settle at max voltage, I fed 19.5V. (It draws 18mA with 5mm LED placed on board)
This is having very very dark background. I could not listen any noise with this in middle of chain. I put my ears to speaker components - nothing. Its like dead. :clapping:
With any source it plays clear and sounds live. I mean each instrument/sound is distinctively identified specially w/ chorus etc. Filled low, controlled high still I can not call as warm but live music. Guitar, flute and violin are clean and superb. Vocals - its always filled and I could listen breathing of singer at some places (with ACD input). Few music pieces are audible at first time. :thumbsup:
Well controlled tight bass. All over complete band is represented nicely. Though I have misplaced speaker positions, I can feel they are absent in the scene. I need to go near to confirm that both are working.
Volume control:
This guy works nicely though I could not figure out any difference between my earlier resistor ladder based stepper and this. I did NO tuning after the build. Even I did not bother to measure the resistances of it.
Only one caveat is there. This does not go to 100% silent on 0 level of volume control. My amp plays little music 1-2% of max level as it has sensitivity of 200mV. This was mentioned at Uriah's site(? somewhere I read). Still in midnight silent I have to increase it from 7'o clock position towards 8'o clock position. Normal listening level is at 9'-10'o clock. That level starts bothering everybody in house. Smooth action and no more steps. Way ahead of normal stereo pot. At low volume all details are retained and that all about it.
CNC:
As commented earlier this is very musical :thumbsup:. I am not repeating same story for this. This needs to open at higher side and tighten up at lower ends. I have to wait for week to complete 30 musical hrs.
It is said that modern OP AMP based phono stages are equivalent to older designs of couple of Sq Ft filled with components. Current draw is approx 12mA for both OP AMP operated at +/-12V.
After increasing to 100% volume w/o records played, I find faint white noise sounds like hiss or FM radio w/o station. This is audible very very faint hiss at volume control set to 100% and vanishes with music. It seems something it getting induced at sensitive input of CNC board. But no need to worry about it as it has to be sensitive to cope with 2.5mV input. Overall silent between tracks of LP w/o any kind of background noise.
Power Supply:
I am happy with this module. It is doing its duty. CNC is working like it is battery powered (forgive me), PASS B1 working dead silent, nothing getting more than warm except those two 330E,2W resistances. Either of them touch to 1.5W dissipation occasionally. At any level, I did not notice any audible noise interference or hum from AC Mains.
I am happy with this complete project. It was worth of all efforts, inclusive burning midnight oil by Sachu888, Quad and me
. Thanks to Sachu888, Quad and all participant for encouragement and support. This reduced cost and we could attain quality. Thanks to CaptRajesh for pushing LDR Volume Control and PS in middle. It completed this preamp. I got satisfaction from all boards we designed and built. This fulfilled long desire of owning PASS B1 based preamp. Thanks everybody!
Regards,
