Want to build a solid state amp, first attempt!

Boscoe · 8th October 2010, 10:31 PM

Okay so my first attempt at a solid state amp, justneed some help basically. The thing that got me into the idea was the 'Best amp that I've very heard' thread. Looking to build something similir but i don't have that budget! So I came up with the rquirements of this amp:

Needs to be dual channel
100Wrms per channel to 8ohm (but want to be able to drive 4ohm too)
For the cooling and the case design of the amplifier I'm want to use TO-220 package style MOSFETs.
I want a active two channel low pass filter output for a sub.
Realistic budget of £200 just for the electronics not chassis or connectors.
I don't want anything like balance, bass control ect. just a simple power amp!
Looking at space I want to stick to the size of a 2u rack case.

If someone could point me in the direction of some schematics and pcb layouts if possible it would be great help!

I have most probably forgot something if someone could point be where would be good!

Thanks
Boscoe

Bigun · 8th October 2010, 10:38 PM

Project 101 - High Power, High Fidelity MOSFET power amplifier

hope this helps.

richie00boy · 8th October 2010, 11:26 PM

That doesn't have TO-220 output devices.

For the sub out unfortunately it's a little more complex than first glance, take a look at the sub-woofer controller project on my website.

Also I have a TO-220 MOSFET amp that I designed somewhere and it worked really nice, I can dig out the schematic and PCB design if you want.

Boscoe · 9th October 2010, 07:44 AM

Quote:

Also I have a TO-220 MOSFET amp that I designed somewhere and it worked really nice, I can dig out the schematic and PCB design if you want.

That would be great if you can, thanks for the help!

richie00boy · 11:11 AM

I found all the stuff out, I remember now I was going to do some tweaking to the layout to improve ease of build. I'll try and get that done over the next few days. I can also put a kit together if you are stuck for the bits.

Boscoe · 9th October 2010, 02:45 PM

Yeh thanks a lot, although I don't need the kit. What sort of power could this acheive?

Russellc · 9th October 2010, 02:48 PM

Have a look at the F-5 over on the Pass forum.

Russellc

AndrewT · 9th October 2010, 05:02 PM

Hi,
100W into 8r0 would be equivalent to 200W into 4r0.
That would need between 600W and 800W of FET output devices.
2pair of irfp240/9240 (To247)would just about do it. 3pair of other 120W to 150W To220 FETs would be a sensible starting point.

You would struggle to get 40Vpk (100W into 8r0) at the output of a FET source follower amplifier from a 35+35Vac transformer, so you would probably use a 40+40Vac transformer. You would need ~400VA to 800VA to meet the 200+200W target.

jaycee · 9th October 2010, 11:22 PM

Quasi's NMOS200 amp would fit the bill I think. IS there any particular reason to use TO-220 mosfets and not TO-247 ? Anyway, he accommodates both with his extremely neat design

Nmos200 - Quasi's DIY Audio Site

Boscoe · 10th October 2010, 08:59 AM

Looks good thanks and both is fine just didn't want TO-3.

8th October 2010, 10:31 PM	#1
Boscoe diyAudio Member Join Date: Feb 2010 Location: England	Want to build a solid state amp, first attempt! Okay so my first attempt at a solid state amp, justneed some help basically. The thing that got me into the idea was the 'Best amp that I've very heard' thread. Looking to build something similir but i don't have that budget! So I came up with the rquirements of this amp: Needs to be dual channel 100Wrms per channel to 8ohm (but want to be able to drive 4ohm too) For the cooling and the case design of the amplifier I'm want to use TO-220 package style MOSFETs. I want a active two channel low pass filter output for a sub. Realistic budget of £200 just for the electronics not chassis or connectors. I don't want anything like balance, bass control ect. just a simple power amp! Looking at space I want to stick to the size of a 2u rack case. If someone could point me in the direction of some schematics and pcb layouts if possible it would be great help! I have most probably forgot something if someone could point be where would be good! Thanks Boscoe

8th October 2010, 10:38 PM	#2
Bigun diyAudio Member Join Date: Jan 2009 Location: K-W Ontario Blog Entries: 2	Project 101 - High Power, High Fidelity MOSFET power amplifier hope this helps. __________________ "The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.

8th October 2010, 11:26 PM	#3
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	That doesn't have TO-220 output devices. For the sub out unfortunately it's a little more complex than first glance, take a look at the sub-woofer controller project on my website. Also I have a TO-220 MOSFET amp that I designed somewhere and it worked really nice, I can dig out the schematic and PCB design if you want. __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more

9th October 2010, 11:07 AM	#5
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	I found all the stuff out, I remember now I was going to do some tweaking to the layout to improve ease of build. I'll try and get that done over the next few days. I can also put a kit together if you are stuck for the bits. __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more Last edited by richie00boy; 9th October 2010 at 11:11 AM.

9th October 2010, 05:02 PM	#8
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, 100W into 8r0 would be equivalent to 200W into 4r0. That would need between 600W and 800W of FET output devices. 2pair of irfp240/9240 (To247)would just about do it. 3pair of other 120W to 150W To220 FETs would be a sensible starting point. You would struggle to get 40Vpk (100W into 8r0) at the output of a FET source follower amplifier from a 35+35Vac transformer, so you would probably use a 40+40Vac transformer. You would need ~400VA to 800VA to meet the 200+200W target. __________________ regards Andrew T.


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9th October 2010, 02:45 PM	#6
Boscoe diyAudio Member Join Date: Feb 2010 Location: England	Yeh thanks a lot, although I don't need the kit. What sort of power could this acheive?

9th October 2010, 02:48 PM	#7
Russellc diyAudio Member Join Date: Mar 2003 Location: midwest	Have a look at the F-5 over on the Pass forum. Russellc

9th October 2010, 11:22 PM	#9
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	Quasi's NMOS200 amp would fit the bill I think. IS there any particular reason to use TO-220 mosfets and not TO-247 ? Anyway, he accommodates both with his extremely neat design Nmos200 - Quasi's DIY Audio Site

10th October 2010, 08:59 AM	#10
Boscoe diyAudio Member Join Date: Feb 2010 Location: England	Looks good thanks and both is fine just didn't want TO-3.

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