Will j109bl duals work instead of the 2n5565 items. I have a nice pile of them.
It seems with an amp of 65-70 volt rails 4 output pairs would be a better choice especially if it is biased on the hot side. I also like the decoupling caps at the output devices. I have read much good press about this Hitachi mosfets. Made especially for audio.
This thread has generated a nice bit of interest in a short time. I hope we are able to get something together. There are never enough new designs to try out with 100+ watt output.
Tad
It seems with an amp of 65-70 volt rails 4 output pairs would be a better choice especially if it is biased on the hot side. I also like the decoupling caps at the output devices. I have read much good press about this Hitachi mosfets. Made especially for audio.
This thread has generated a nice bit of interest in a short time. I hope we are able to get something together. There are never enough new designs to try out with 100+ watt output.
Tad
My personal choice would still be the 2N5565's and either three pairs of MOSFETS, or two pairs.
Count me in as a customer for the PCB board if Alex can do the following:
1.) Add rail fuses.
2.) Remove the small heatsink from BSS71/BSS74 and place the BD249C/BD250C near the output MOSFETS, so they can be mounted on that same main heatsink.
3.) Go back to a three pair MOSFET design.
4.) Leave the MOSFET 10nF decoupling capacitors.
Count me in as a customer for the PCB board if Alex can do the following:
1.) Add rail fuses.
2.) Remove the small heatsink from BSS71/BSS74 and place the BD249C/BD250C near the output MOSFETS, so they can be mounted on that same main heatsink.
3.) Go back to a three pair MOSFET design.
4.) Leave the MOSFET 10nF decoupling capacitors.
As far as I remember, you can print a pdf file at certain ratio which can adjust to you requirement. The most important thing is that you would have to have some grids along the pcb so you can make measurements on your print out and see if they are print with the right ratio. That's what I do with all my pcbs. Alex, pls kindly add that to your pcb to make things easier.
Is it possible to use Vishay/Siliconix U430 instead of? I have some of these.
Hmmm... I don't think it will be that easy and quick... to find something that deserve the "by far the very best I have ever heard and I've heard them all". Too good to be true, don't you think? Especially when you didn't disqualify class-A amps.
1. I believe that in the future more people will love the lateral mosfet amps. I have been waiting for such moment when a superior design will be created. Paralleling output mosfet has drawbacks and benefits (e.g. input capacitance versus transconductance). Then it is logical to guess that there must be an optimum number of pairs, and three seems to be the one for this?
2. Separate supply for the front end... almost every amp will benefit from this. Since I'm only after good amps, I have always used separate supply since I built my MF A1 (12V front end) and Stochino (56V front end) for the higher voltage. I have done many tweaking with the types of the front end regulators, so I have a feeling that the one in the diagram is not optimal.
3. Majority of people like the typical JFET input, no doubt. Very quiet yes, but a bit boring imo (especially for low current). That's for the typical K170. I like mosfet better even tho the transconductance is lower and distortion is higher. It seems the specified 2N input JFET has characteristics that is closer to mosfet than K170. Then I miss the chance of building this amp with the preferred JFET.
4. I think the key success/failure of LMOSFET amps is the driver for the FET. I will build or not build an LMOSFET amp simply from looking at its driver. This one is okay, tho like LineUp said, nothing unusual. I have built similar amp based on MP300 input stage. The MP300 is a drain follower where the gate is driven by driver's collector. To have stronger drive, the gate is modified to be driven by emitter follower (hence a source follower) and increased driver's voltage a-la NSA amplifier. Since I cannot design one, I have not many option but have to build this one also
Hi Alex,
PCB B is better and is the one I'd be interested in. This is nearly a perfect board. Few nitpicks if you could change would make it perfect IMO.
1.) This one is important. Can you please change the 2SK170's to 2N5565's. At least as an option. Instead of PCB A, maybe you can use PCB B with the 2N5565's. This way some people can order one board and others can order the other.
2.) The 100nF capacitors are not needed IMO.
3.) Can you label the following: BSS71, BSS74, BC546B, BC182B, MPSA93, MPSA43.
4.) I see you've omitted the 47uF capacitors in the power supply. If you're using 10,000uF, can you add in addition 100uF capacitors? The main power supply should be 10,000uF - 100uF - 1uF - 10nF. It does make a difference sonically.
5.) The 220uF capacitor from 330ohm resistor going to ground is not necessary IMO. Also, you've included 2 1uF capacitors in the main power supply, only one is really needed. And the 1N5408 diodes are also not necessary IMO.
This again looks like an excellent board. What determines my purchase is if the 2N5565's are put in.
Thanks!
PCB B is better and is the one I'd be interested in. This is nearly a perfect board. Few nitpicks if you could change would make it perfect IMO.
1.) This one is important. Can you please change the 2SK170's to 2N5565's. At least as an option. Instead of PCB A, maybe you can use PCB B with the 2N5565's. This way some people can order one board and others can order the other.
2.) The 100nF capacitors are not needed IMO.
3.) Can you label the following: BSS71, BSS74, BC546B, BC182B, MPSA93, MPSA43.
4.) I see you've omitted the 47uF capacitors in the power supply. If you're using 10,000uF, can you add in addition 100uF capacitors? The main power supply should be 10,000uF - 100uF - 1uF - 10nF. It does make a difference sonically.
5.) The 220uF capacitor from 330ohm resistor going to ground is not necessary IMO. Also, you've included 2 1uF capacitors in the main power supply, only one is really needed. And the 1N5408 diodes are also not necessary IMO.
This again looks like an excellent board. What determines my purchase is if the 2N5565's are put in.
Thanks!
Thanks, appreciated. I have far less experience with high end amps. My F5 is currently the best little amp I've heard. From the big pro-amps, I recall a Crest who wasn't too bad and from consumer types I kind of liked the Technics SU-A1. Of course, you will agree that the amp-speaker combination is not to be neglected. What speakers would be a good match for this fellow?
/Hugo