NEW class A :Constant Current Push Pull amplifier with single SMPS and hybrid preamp

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Joined 2015
Floating Single Supply
This type of power supply provides very high transient energy , the SMPS works in constant current mode , on condition that the two outputs are perfectly complimentary . I tried this technique with great success on sublimed JLH .
Constant Current Push Pull
To obtain a perfect complimentary ,instead of fighting against the windmills , I said why not have one of the outputs regulates itself for constant current as SRPP, but acting oppositly to the current of the capacitors . When the capacitors asking more or less current the regulated output passes less or more current modulating itself by trying to keep the total current constant . This how is born the CCPP ,Constant Current Push Pull amplifier. Unlike the SRPP it does not subtract the even harmonics neither adds the odd ones , it just duplicates the current of the driving transistor . By this the transfer function of the amplifier is that of a single ended .
By using a mosfet as driving output transistor and a mosfet error amplifier with 35db NFB ratio , it results very low distortion of mainly even orders with very very high definition.
The IRFP9240 has reverse capacitance of 80pf and results an open loop frequency response of 30khz. The input SMD mosfet ssm3k339 has reverse capacitance of 7pf and 120pf input yielding more than 1Mhz closed loop response.
The high frequency current regulator 2sc3597 is mounted upon the heatsink or on the current transistor to have some thermal regulation. The capacitor on its collector tunes the high frequency character of the sound .
The draw back of CCPP circuit , it doesn't have any ripple rejection . Every word uttered by the power supply is heard on the speaker , for that the power supply must be filtered . This SMPS is not equipped neither with EMI filter , although it is full silent after filtering for measurements sake it might need one unit of EMI filter for both channels .
This SMPS (48v/2A)does not start with the high value capacitors , others ones do. I added a soft start circuit which can be mounted on a separate pcb along with the filter on a small heatsink .
Kokoriantz
 

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Disabled Account
Joined 2015
hybrid preamp

Special amplifier requires a special preamp or predriver . The very high quality of the CCPP amplifier gets diminished by standard tube preamps . So I created this dedicated ,one tuned to match the CCPP. The power supply uses standard transformers 220v/2x15v 800ma with separate compartments and 2x12/220 500ma for step up .
The input tube has a ruler straight varying transconductance . Not only it stains the sound with even order harmonics but also expends the dynamic . It is particularly designed audio tube that introduces a metallic sound at preconized 7.5ma , but dissappears at 5.5ma.I adjusted for the velvet voice of Peggy Lee at 6.2ma . The coupling capacitor value 1uf and type determines the low frequency character. R22 22k adjusts the required even order harmonics to be added . It is adjusted just enough to have the voices of CCPP human.
The opamp is not any ordinary . It has open loop response of >10khz, essantial for this circuit . The gain is fixed by R3 about 12db so that 0.5Vrms can fully drive the CCPP. This preamp extends further the tonality of the CCPP amplifier with finner high fequencies.
Kokoriantz
 

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