even more lateral fets
#1 even more lateral fets
overwhelmed I was by the phenominal enthusiasm for the last lateral fet amp, so I am moved to post another.
Voila! The choke loaded source follower lateral fet amplifier. Similar to the MOFO championed by Mike Rothacher on diyaudio but with a leteral fet and a smaller choke. This one has an opamp front end giving a gain of 3 because I don't have any active pre-amp to feed it. it will be powered from half the ps of the other amp and 2 large 24v smps that I had lying around.
because I'm not sure of the heat sink dissipation figures I'm going to start the bias at about 1.1 amps(30ish watts) and hope it will move to 1.6 amps without getting too hot.
fingers crossed.
and another of the ps
Voila! The choke loaded source follower lateral fet amplifier. Similar to the MOFO championed by Mike Rothacher on diyaudio but with a leteral fet and a smaller choke. This one has an opamp front end giving a gain of 3 because I don't have any active pre-amp to feed it. it will be powered from half the ps of the other amp and 2 large 24v smps that I had lying around.
because I'm not sure of the heat sink dissipation figures I'm going to start the bias at about 1.1 amps(30ish watts) and hope it will move to 1.6 amps without getting too hot.
fingers crossed.
and another of the ps
There's nowhere you can be that isn't where you're meant to be
#2 Re: even more lateral fets
I may have to put this one on hold.
Just testing 1 channel at 1.0 amp the sink got to 50 degrees, and it was still showing signs of climbing, albeit very slowly.
I need bigger sinks for this...oh waily waily...this was supposed to be a cheap experiment.
The meter showed 34 watts out of the wall.
Just testing 1 channel at 1.0 amp the sink got to 50 degrees, and it was still showing signs of climbing, albeit very slowly.
I need bigger sinks for this...oh waily waily...this was supposed to be a cheap experiment.
The meter showed 34 watts out of the wall.
There's nowhere you can be that isn't where you're meant to be
#3 Re: even more lateral fets
Heat is always the problem with solid state it seems.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
- pre65
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#4 Re: even more lateral fets
What about a fan to cool things like wot I used on my 50W S/E Mosfet amps ?ed wrote: ↑Thu Jun 21, 2018 10:38 am I may have to put this one on hold.
Just testing 1 channel at 1.0 amp the sink got to 50 degrees, and it was still showing signs of climbing, albeit very slowly.
I need bigger sinks for this...oh waily waily...this was supposed to be a cheap experiment.
The meter showed 34 watts out of the wall.
The only thing necessary for the triumph of evil is for good men to do nothing.
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
#5 Re: even more lateral fets
seriously?
fans are for air conditioning and computers, eny fule know!
I had a fan in an MF A100 back in the eighties, my first and last...the fan didn't stop the A100 sounding awesome but it did stop the music.
I'll just have to wait for my birthday and convince the boss to buy me some...if anybody has a couple lying around please let me know..min 0.75 c/w
There's nowhere you can be that isn't where you're meant to be
#6 Re: even more lateral fets
it's alive
unforunately my poor little sig gen only goes to about 1.6v RMS so I couldn't find the clipping point
but it sings
I could only run it for half an hour but it sounds awesome even hamstrung at 1A bias. This has promise.
unforunately my poor little sig gen only goes to about 1.6v RMS so I couldn't find the clipping point
but it sings
I could only run it for half an hour but it sounds awesome even hamstrung at 1A bias. This has promise.
There's nowhere you can be that isn't where you're meant to be
#7 Re: even more lateral fets
Improvise man, you must have a mains transformer that you can use as a step up or if its a dual primary an autoformer to give you 6dB of gain.unforunately my poor little sig gen only goes to about 1.6v RMS so I couldn't find the clipping point
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
#8 Re: even more lateral fets
you've found a nerve, reminding me how useless I am these days...I have a pot in the workroom where I put details of projects on hold. These are usually mid point when the boy comes in: 'Dad, can you fix this please, it was an accident, honest'...so, about 3 or 4 years ago I was in the middle of a replacement sig gen..I've just found the outline in aforementioned pot...here it is:
I can't bring myself to fiddle with the old one when this is still unfinished.
It did occur to me that the old one had an opamp buffer on the output, I suppose I should have put some gain in at that point...c'est la vie.
the clipping point is one for the future...I was listening to it during my 30 minute window of opportunity before it set fire to the music room, when the mem sahib came in and said 'isn't that a bit loud!!'
I can't bring myself to fiddle with the old one when this is still unfinished.
It did occur to me that the old one had an opamp buffer on the output, I suppose I should have put some gain in at that point...c'est la vie.
the clipping point is one for the future...I was listening to it during my 30 minute window of opportunity before it set fire to the music room, when the mem sahib came in and said 'isn't that a bit loud!!'
There's nowhere you can be that isn't where you're meant to be
- IslandPink
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#9 Re: even more lateral fets
Good effort Ed.
What's the tone like - different to a Mosfet output ?
Have you got a link to the DIY-A thread ?
What's the tone like - different to a Mosfet output ?
Have you got a link to the DIY-A thread ?
"Once you find out ... the Circumstances ; then you can go out"
#10 Re: even more lateral fets
far too early to nail it down...the brief listen was fairly bright and ultra revealing of minutae, the bass was profundo..the music was dirt-like, dirt like.IslandPink wrote: ↑Fri Jun 22, 2018 12:56 pm Good effort Ed.
What's the tone like - different to a Mosfet output ?
Have you got a link to the DIY-A thread ?
bear in mind I was aiming to see if I could identify the aforementioned difference, I thought no better place than a single stage, single ended, and I also have an ultra simple pp to compare it with....
there will be more, maybe, I'm conscious of posting into a void at the moment....
I'm confident that the large smps are workable though...
just google mofo amplifier for background but imo you must read Mike's 'build this mofo' paper, it's a real hoot.
There's nowhere you can be that isn't where you're meant to be
- IslandPink
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#11 Re: even more lateral fets
Better than the music being 'dud-like' ( ...and they called that .... tobacco juice .. )
Thanks for the circuit. suspect that 1058 thing can handle a far bit of current. So is the 60mH like the loading on a valve, then ?
Thanks for the circuit. suspect that 1058 thing can handle a far bit of current. So is the 60mH like the loading on a valve, then ?
"Once you find out ... the Circumstances ; then you can go out"
- IslandPink
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#12 Re: even more lateral fets
Had a look at the datasheet.
So, looks like you could run 2 or 3A with more heatsinking ?
Input capacitance looks very flat vs. Vgs from -2V onwards . This seems like a very good thing.
I had a look at the datasheet for IRFP240 used in the Pass F4 and not sure I could find an equivalent graph , but the capacitance vs. Vds was pretty non-linear.
So, looks like you could run 2 or 3A with more heatsinking ?
Input capacitance looks very flat vs. Vgs from -2V onwards . This seems like a very good thing.
I had a look at the datasheet for IRFP240 used in the Pass F4 and not sure I could find an equivalent graph , but the capacitance vs. Vds was pretty non-linear.
"Once you find out ... the Circumstances ; then you can go out"
#13 Re: even more lateral fets
I've decided to build another one of these...I loved the sound of the first one and all the talk of current mofos has spurred me on..
I'm going to use the exicon fet again though cos I think it's great.
but I've got some changes planned, to wit:
Use the bigger chokes and max out the current
Use a proper case with some Conrad heatsinks
change the opamp to a Muses02 from the original LTC1150, but may up the gain slightly from 3 to 4(it's got rave reveiws from the Topping DAC)
or
replace the opamp with DA6116 which goes to a gain of 15db and integrate an IR remote control.
In regard to the front end I think I’m quite keen to try one of these Muses opamps, and it might be fun to compare with Steve’s valve front end when we finally escape.
Also, I did think the IR remote control and integrated scenario might be a bit OTT as the Topping E3 that I’m looking at has an IR remote for the volume. I miss the armchair control of the SB and the current control via netbook cannot be in range of the listening chair....oh compromise waily
I'm going to use the exicon fet again though cos I think it's great.
but I've got some changes planned, to wit:
Use the bigger chokes and max out the current
Use a proper case with some Conrad heatsinks
change the opamp to a Muses02 from the original LTC1150, but may up the gain slightly from 3 to 4(it's got rave reveiws from the Topping DAC)
or
replace the opamp with DA6116 which goes to a gain of 15db and integrate an IR remote control.
In regard to the front end I think I’m quite keen to try one of these Muses opamps, and it might be fun to compare with Steve’s valve front end when we finally escape.
Also, I did think the IR remote control and integrated scenario might be a bit OTT as the Topping E3 that I’m looking at has an IR remote for the volume. I miss the armchair control of the SB and the current control via netbook cannot be in range of the listening chair....oh compromise waily
There's nowhere you can be that isn't where you're meant to be
#14 Re: even more lateral fets
The designers of this LatFET amp have very high aspirations so it will be interesting to see the feedback from the builders. XRK has built a lot of amps so he is well placed to assess it. Expensive BOM though.
https://www.diyaudio.com/community/thre ... ts.350957/
https://www.diyaudio.com/community/thre ... ts.350957/
"Its good enough for Government work."
#15 Re: even more lateral fets
moving on from post #13...things move lightening fast here.
more cutting, drilling, filing and bleeding this may actually happen sometime soon...
more cutting, drilling, filing and bleeding this may actually happen sometime soon...
There's nowhere you can be that isn't where you're meant to be