which amp is this?

nazirdigi · 12th December 2010, 09:37 AM

nice pcb layout anybody know this amp pls explain and watts,v.
what are the transistors used.

djk · 12th December 2010, 06:40 PM

A quasi-comp all N-channel Hexfet design. It has a bias transistor on the heatsink, so it's probably class AB. The 63V caps suggest it should run at about ±57V or so, maybe 300W/4R.

ontoaba · 08:53 AM

Not a good pcb, an electrolyt may explode. Not good design, it has huge drop voltages that means it lost much power rating and getting very hot. 14dBgain for high open loop gain will affect in high damping factor, it will not satisfy your ear for long time listening.

ravslanka · 13th December 2010, 06:14 PM

hi nazirdigi

this is quasi nmos350 workin on +-70 vols.this is nmos200 pcb modified by me.
forgot to raise the caps voltages.you can find the schematic and pcb on quasis site.
Nmos350 / 500 - Quasi's DIY Audio Site

regards

ravs

be a vegeterian.......

quasi · 14th December 2010, 01:21 AM

Yup, looks like a hot-ed up Nmos200. Nice work Ravs.

Q

ravslanka · 14th December 2010, 05:28 AM

hi quasi,

no see long time whats going on

ravs

be a vegeterian....

djk · 14th December 2010, 12:36 PM

http://sites.google.com/site/quasisd...attredirects=0

T7 would benefit from a resistor in the range of 330R in series with the base. This resistor prevents the voltage reference (D1, D2) from collapsing when T7 saturates during a negative clip, improving the recovery time (see any Pass amplifier schematic with a similar front-end).

I would also consider using gate zeners if driving a 2R load.

quasi · 15th December 2010, 03:49 AM

Quote:

Originally Posted by ravslanka

hi quasi,

no see long time whats going on

ravs

be a vegeterian....

Hi Ravs
My life is so busy man and I have little time for DIY. Even so I recently helped a friend build a set of AOS transmission line speakers (very nice) and I have begun to build an Nmos350 Mk2.5 (not yet published) as well as some other small electronics projects (non-audio).

I am also trying to landscape our garden, raise 2 sons, keep a happy wife and a hectic job.

How's life with you man?

Cheers
Q

nazirdigi · 18th December 2010, 12:02 AM

hai ravslanka can u upload the working pcb layout and the changes .what are the voltage do u use and the transistor.

12th December 2010, 06:40 PM	#2
djk diyAudio Member Join Date: Feb 2001 Location: USA	A quasi-comp all N-channel Hexfet design. It has a bias transistor on the heatsink, so it's probably class AB. The 63V caps suggest it should run at about ±57V or so, maybe 300W/4R. __________________ Candidates for the Darwin Award should not read this author.

13th December 2010, 08:29 AM	#3
ontoaba diyAudio Member Join Date: Nov 2009 Location: Kudus, & Malang	Not a good pcb, an electrolyt may explode. Not good design, it has huge drop voltages that means it lost much power rating and getting very hot. 14dBgain for high open loop gain will affect in high damping factor, it will not satisfy your ear for long time listening. Last edited by ontoaba; 13th December 2010 at 08:53 AM.

14th December 2010, 12:36 PM	#7
djk diyAudio Member Join Date: Feb 2001 Location: USA	http://sites.google.com/site/quasisd...attredirects=0 T7 would benefit from a resistor in the range of 330R in series with the base. This resistor prevents the voltage reference (D1, D2) from collapsing when T7 saturates during a negative clip, improving the recovery time (see any Pass amplifier schematic with a similar front-end). I would also consider using gate zeners if driving a 2R load. __________________ Candidates for the Darwin Award should not read this author.

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13th December 2010, 06:14 PM	#4
ravslanka diyAudio Member Join Date: Oct 2006 Location: delhi	hi nazirdigi this is quasi nmos350 workin on +-70 vols.this is nmos200 pcb modified by me. forgot to raise the caps voltages.you can find the schematic and pcb on quasis site. Nmos350 / 500 - Quasi's DIY Audio Site regards ravs be a vegeterian.......

14th December 2010, 01:21 AM	#5
quasi diyAudio Member Join Date: Sep 2004 Location: Adelaide, Australia	Yup, looks like a hot-ed up Nmos200. Nice work Ravs. Q

14th December 2010, 05:28 AM	#6
ravslanka diyAudio Member Join Date: Oct 2006 Location: delhi	hi quasi, no see long time whats going on ravs be a vegeterian....

18th December 2010, 12:02 AM	#9
nazirdigi diyAudio Member Join Date: Oct 2009	hai ravslanka can u upload the working pcb layout and the changes .what are the voltage do u use and the transistor.

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