Hello, do you think this amp is designed good enough?
I am planning to use it bridged, but I read here some threads where bridging a certain amp was said to be unstable or what.
More, i want to increase the driver voltage by 10V, for the MJE350 and prats to the left.
The power supply is gonna be +-48V, plus the 2x10V for the driver,
I want to get 350W@8oms, into only a woffer, because it will be amp for bass guitar.
I am planning to use it bridged, but I read here some threads where bridging a certain amp was said to be unstable or what.
More, i want to increase the driver voltage by 10V, for the MJE350 and prats to the left.
The power supply is gonna be +-48V, plus the 2x10V for the driver,
I want to get 350W@8oms, into only a woffer, because it will be amp for bass guitar.
Attachments
A) Those MOSFETs are expensive, and you will need three pair per half of the bridge amp to drive 350W/8R reliably.
B) Those MOSFETs sound a bit 'muddy' to me. I prefer a 'tighter' sound to my bass.
C) For a similar front end with a more robust output stage that sounds 'tighter' and costs less, I would build the Super Leach.
http://users.ece.gatech.edu/~mleach/superamp/
A similar version of this amp was produced commercially as the Heathkit AA1800. It tested at 400W/8R with ±95V rails.
If you already have your suppy bought, just build a pair of the v4.5 Leach and bridge. It will put out the same power, and a pair uses the same number of output devices.
B) Those MOSFETs sound a bit 'muddy' to me. I prefer a 'tighter' sound to my bass.
C) For a similar front end with a more robust output stage that sounds 'tighter' and costs less, I would build the Super Leach.
http://users.ece.gatech.edu/~mleach/superamp/
A similar version of this amp was produced commercially as the Heathkit AA1800. It tested at 400W/8R with ±95V rails.
If you already have your suppy bought, just build a pair of the v4.5 Leach and bridge. It will put out the same power, and a pair uses the same number of output devices.
I like the Pass/Thagard A75 - see www.passdiy.com
I modified it slightly for 65V front end and 59 V output rails (42VAC transformer) You could go a little higher rails, but cooling the front end becomes an issue unless you redesign to reduce current in the VAS. I run 6 pairs of Fairchild IRFP240/9240.
I've also bridged Leach 4.5s on 60V rails - performed quite nicely into 8 ohms. You could easily modify it to run on higher rails, just use MJE15032/33 drivers and MJL4281/4302 or MJL3281/1302 for outputs. Follow Leach's directions for the front end changes.
It wouldn't be too difficult to modify the Leach for a MOSFET output stage - replace the Vbe multiplier device with a mosfet like IRF610 mounted on the heat sink, and skip the compensation diodes, and change the base stopper resistors from 3R3 to 221R or so. Power the front end from a separate regulated supply and away you go. I haven't actually done this yet, so beware.
I modified it slightly for 65V front end and 59 V output rails (42VAC transformer) You could go a little higher rails, but cooling the front end becomes an issue unless you redesign to reduce current in the VAS. I run 6 pairs of Fairchild IRFP240/9240.
I've also bridged Leach 4.5s on 60V rails - performed quite nicely into 8 ohms. You could easily modify it to run on higher rails, just use MJE15032/33 drivers and MJL4281/4302 or MJL3281/1302 for outputs. Follow Leach's directions for the front end changes.
It wouldn't be too difficult to modify the Leach for a MOSFET output stage - replace the Vbe multiplier device with a mosfet like IRF610 mounted on the heat sink, and skip the compensation diodes, and change the base stopper resistors from 3R3 to 221R or so. Power the front end from a separate regulated supply and away you go. I haven't actually done this yet, so beware.
www.diyaudio.com/forums/showthread.php?postid=498232#post498232
I've constructed a fair number of DIY complementary mosfet amplifier designs since the Hitachi appl. note
The Pass/Thagard A75 being the most balanced full SS design. I used really cheap IRF630/9630 for the output stage, as they looked very similar to one of the advised device couples.(likely to still have a few hundred of them)
You should still be able to buy a complete A75 board set for less than $30 at Xpress.
If you desire a whole lot of power, Quasi's amp should be your flavor, i think.
I've constructed a fair number of DIY complementary mosfet amplifier designs since the Hitachi appl. note
The Pass/Thagard A75 being the most balanced full SS design. I used really cheap IRF630/9630 for the output stage, as they looked very similar to one of the advised device couples.(likely to still have a few hundred of them)
You should still be able to buy a complete A75 board set for less than $30 at Xpress.
If you desire a whole lot of power, Quasi's amp should be your flavor, i think.
richie00boy said:search on user 'quasi' he is probably the most prolific poster on here regarding n-channel amps, not forgetting kanwar
Hi Kubeek,
Have a look at this...
http://www.diyaudio.com/forums/attachment.php?s=&postid=937736&stamp=1150022131
http://www.diyaudio.com/forums/showthread.php?s=&threadid=56833
K a n w a r
If the first circuit is the one with a pair "up" and a pair "down" (2x2SK and 2x2SJ), it looks like the schematic calls for 100mA per leg. With +/- 30V rails, that gives 3 Watts per device. It's good that there's plenty of heat sink. You could open one of the rail fuses, replace it with your DC current meter and adjust for something more that 200mA. 100mA per leg + the current to power the VAS. If you need to get a little more accurate adjusting just the output stage, you could insert the current meter into the lines that just feed the output MOSFET's
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