I've worked in the audio industry for more than 10 years, this is by far the very best amplifier I have ever heard and I've heard them all.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
The topology is not unusual.
There are amplifiers which are almost like that.
There are 3 things I notice are a bit special.
- The use of a DUAL JFET in input.
- The triple paralleled 2SK134/2SJ49 lateral MOSFETs in output.
- The separate regulated input/VAS supply.
The last point, the separate regulated supply for Input/VAS
is something I have recommended many times.
Because it is just crazy to supply the sensitive first stages
from a heavy current un-clean output supply.
Still stupid designers, over and over, keep on putting all of one power amplifier
to use one and same suppply!
This shows a fundamental lack of understanding what happens
when we run an audio amplifier feeding loudspeakers.
There are amplifiers which are almost like that.
There are 3 things I notice are a bit special.
- The use of a DUAL JFET in input.
- The triple paralleled 2SK134/2SJ49 lateral MOSFETs in output.
- The separate regulated input/VAS supply.
The last point, the separate regulated supply for Input/VAS
is something I have recommended many times.
Because it is just crazy to supply the sensitive first stages
from a heavy current un-clean output supply.
Still stupid designers, over and over, keep on putting all of one power amplifier
to use one and same suppply!
This shows a fundamental lack of understanding what happens
when we run an audio amplifier feeding loudspeakers.
I completely agree with you regarding the regulated power supply for the input stage. I haven't seen this kind of topology in other amplifiers, per se. Which amps are almost identical?
Hello,
Lineup, sometimes stupid designers need to meet marketing/cost/retail functions to make profit, it helps to sustain the medium ....... Profits!!!
Nice PCB layout Alex
regards,
Lineup, sometimes stupid designers need to meet marketing/cost/retail functions to make profit, it helps to sustain the medium ....... Profits!!!
Nice PCB layout Alex
regards,
Is the PCB accurate enough to etch? Can we get the layout files?
What kind of power and rail voltage can we expect/use on this?
What kind of power and rail voltage can we expect/use on this?
Power rating is approximately 250 watts (2-8 ohms).
Frequency bandwidth is +/- 3dB from 0Hz-1MHz.
This is a wide bandwidth amplifier, sounds incredible. I understand that the metal can military dual jfets 2N5565's are obsolete and dificult to find, but they are significantly superior to 2SK170's.
Same goes for the output MOSFETS. But I agree that this is a logical upgrade, since all the parts are readily available.
Frequency bandwidth is +/- 3dB from 0Hz-1MHz.
This is a wide bandwidth amplifier, sounds incredible. I understand that the metal can military dual jfets 2N5565's are obsolete and dificult to find, but they are significantly superior to 2SK170's.
Same goes for the output MOSFETS. But I agree that this is a logical upgrade, since all the parts are readily available.
Looks like the 2N5565's are 28 bucks for a pair.
I think I may try this amp out though. It looks interesting.
I think I may try this amp out though. It looks interesting.
The gate resistor value seems quite low (100R). On lateral mosfet amplifiers that I have rebuilt recently I have used 1K for the N channel and 680R for the P channel. The 2 differing resistances helping to compensate for the different gate capacitance values.
I know that the old Hitachi mosfets are more forgiving than the modern equivalents that most of us have to use.
The driver and output stage are very similar to my modified Rauch DVT 50S, which is what I use in my current home system.😎
I know that the old Hitachi mosfets are more forgiving than the modern equivalents that most of us have to use.
The driver and output stage are very similar to my modified Rauch DVT 50S, which is what I use in my current home system.😎
Alex,
I sure would like to have some nice machine routed pcb's of this amp produced. Does anyone have any reservations to this.
Now how do we get the files to a job shop.
Tad
I sure would like to have some nice machine routed pcb's of this amp produced. Does anyone have any reservations to this.
Now how do we get the files to a job shop.
Tad
A group buy board or just files to etch my own are fine by me. I actually have been looking something to etch my self as I have a bunch of copper clad.
Is it usably stable at 2 ohms?
Could someone post a list of the fets and and their availability/alternates???
Could someone post a list of the fets and and their availability/alternates???
Doug,
I have never gotten myself involved in etching my own stuff. If the post by Alexmm is to scale, the dimensions are printed on the board, it should not be to terrible hard to transfer to the laser printer and make.
Does anyone know if this a commercially manufactured amp. Where did this design come from? I have been looking for something greater than 100 watts with jfets in the frontend.
Now how hard is it going to be to source most of the specified components. Most of the good Japanese transistors are scarce and expensive here in the U.S.
Tad
I have never gotten myself involved in etching my own stuff. If the post by Alexmm is to scale, the dimensions are printed on the board, it should not be to terrible hard to transfer to the laser printer and make.
Does anyone know if this a commercially manufactured amp. Where did this design come from? I have been looking for something greater than 100 watts with jfets in the frontend.
Now how hard is it going to be to source most of the specified components. Most of the good Japanese transistors are scarce and expensive here in the U.S.
Tad