Think you know but could i suggest if doing the live test DC at input and connected load, that use some inexpensive or not important speakers/drivers to do the test, this just to be sure not to hurt any coils/drive trains in important/expensive MF/HF drivers.
OK. Thanks LC.
BTW smps is great improvement over analog ps. A totally different amp. !!!
I told you guys long time ago, I perform a lot of tests so you don't have to worry about anything. 😎
I'm glad that you hear the same difference over conventional PSU. Toroids and big elco banks are a history for me.
My opinion it all depends how you like it to sound
I always say it sounds different never say improved or better😛
I always say it sounds different never say improved or better😛
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At certain point one comes to a conclusion that better is the right word.
I recommend to try it some day. 😉
I'm a beta tester of a new SMPS brand .I test the F1 with it but also these modules from Thel Audio Audiophiler Hochstrom-Spannungsregler, einstellbar, Voltage Regulator
Very good. Some guys I know also likes the use of linear regulators after conventional PSU, my suggestion was they should test unregulated SMPS + linear regulator.
So far I prefer SMPS1200, but still opened to listen to rival contender.
So far I prefer SMPS1200, but still opened to listen to rival contender.
LC is TR2 usefull for dc offset?
I tried ΤR1 but the best i can take is 7mv and then goes to negative.
too big steps for very small adjustments.
I tried ΤR1 but the best i can take is 7mv and then goes to negative.
too big steps for very small adjustments.
Hi back
TR1 and TR2 sets DC offset plus VAS bias current at the same time. Both works in pairs reciprocally as explained in User manual instructions - last chapter. +/- 5 mV of output DC offset is easy to set with TR1 and TR2, which is quite remarkable result as we speak of no DC servo control here. VAS bias current is 12 mA at cold start, also set with TR1 and TR2.
TR3 sets the output bias current which for the whole amp (complete amp's idle current - no signal connected) has to be 280 mA.
Hopefully you'll find the way to persuade the amp to work as intended.
Please be very careful, measuring probes sometimes likes to jump between pads making short circuits with catastrophical results.
Regards, L.C.
TR1 and TR2 sets DC offset plus VAS bias current at the same time. Both works in pairs reciprocally as explained in User manual instructions - last chapter. +/- 5 mV of output DC offset is easy to set with TR1 and TR2, which is quite remarkable result as we speak of no DC servo control here. VAS bias current is 12 mA at cold start, also set with TR1 and TR2.
TR3 sets the output bias current which for the whole amp (complete amp's idle current - no signal connected) has to be 280 mA.
Hopefully you'll find the way to persuade the amp to work as intended.
Please be very careful, measuring probes sometimes likes to jump between pads making short circuits with catastrophical results.
Regards, L.C.
at the begining they were 1-2mv but after burn in two of the modules climb up at 7mv and the other 2 at 25mv.
i brought down at 7mv them two but now i will try for even lower,or should i left them there?
i brought down at 7mv them two but now i will try for even lower,or should i left them there?
Hi Back, if it's same procedure as on VSSA it's a balance and need concentration. Both TR1/TR2 increase VAS bias in clockwise direction, and decrease Vas bias anti clockwise, as qouted LC you shall end up at 12mA when cold. Which one (TR1/TR2) needed to be turned depend on DC offset, if DC offset is too positive the one pull offset in negative voltage, and if DC offset is too negative the other pulls offset in positive direction. Using two DMM is best, this way you have reading of VAS bias and DC offset in realtime. You need all time to read and strategic pick the correct trimmer to end up 12mA and no DC offset.
Here is visual helper from VSSA thread though VAS bias had another target: http://www.diyaudio.com/forums/vend...lateral-mosfet-amplifier-321.html#post3814157.
Here is visual helper from VSSA thread though VAS bias had another target: http://www.diyaudio.com/forums/vend...lateral-mosfet-amplifier-321.html#post3814157.
Hi LC,
Lazycat FO v1.1 & v1.2 landing to Singapore .thanks nice job.
Tonight I have to compair with FO v1.1 with my dartzeel cTH 8550.
Cheers
Lazycat FO v1.1 & v1.2 landing to Singapore .thanks nice job.
Tonight I have to compair with FO v1.1 with my dartzeel cTH 8550.
Cheers
+1
Definitely use two DMM, much easier and faster to get correct bias.
For setting bias of my F5 I even used three DMM, my F5 has a common PS for both channels, so setting bias on one channel had impact on the other channel.
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For the measurement of VAS bias current, Brytt writes "when cold". For how long after switching on it stays "cold" for those measurements to be accurate?
Mark.
Mark.
If mounted to proper heatsink 1 minute is an appropriate time to set DC offset and VAS bias at cold start. Later, when heated DC offset should be rechecked and corrected but only with one trimmer (TR1 or TR2), not affecting VAS bias.