PASS 50W single ended mosfet amp.

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Michael L
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#331 Re: PASS 50W single ended mosfet amp.

Post by Michael L »

ed wrote: Fri Apr 28, 2017 6:45 pm the bird, the bird is the word, the word's the bird....oh yeah

anyway, at risk of sounding like the record's stuck try this Michael :

http://www.firstwatt.com/pdf/art_leave_classa.pdf

if you're really interested there is tutorial type stuff from novice to master here, I would recommend it to anyone that is interested in class A and/or mosfets..
Very useful info - thanks
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pre65
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#332 Re: PASS 50W single ended mosfet amp.

Post by pre65 »

ratbagp wrote: Fri Apr 28, 2017 7:28 pm At some stage there was discussion about inserting a trimmer resistor in series with the 10K resistor near the CCS mosfet. Was it really necessary?

ray
Not in my case, following the circuit to the letter.
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#333 Re: PASS 50W single ended mosfet amp.

Post by ratbagp »

I've still been thinking of how to build this amp with alternate heat sinking. My latest idea is to attach the mosfets to the flat side of a metal beer bucket like this. Fill with water and plug any leaks. If the water is getting too hot, simply scoop some out and replace with cold water or ice cubes.



ray
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Greg
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#334 Re: PASS 50W single ended mosfet amp.

Post by Greg »

Why stop there, Ray? Drill a couple of holes, some simple plumbing, a pump and a small refrigerator is all you need for constant cooling. Of course, the pump and fridge will require dedicated LPSU's :wink:
Michael L
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#335 Re: PASS 50W single ended mosfet amp.

Post by Michael L »

It would be a pity to waste the heat. Do you have a greenhouse?
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#336 Re: PASS 50W single ended mosfet amp.

Post by ratbagp »

No greenhouse but in winter it would help to heat the house.

I don't think I would need the fridge. I went to a web site that calculates how long it takes to heat water.

http://processheatingservices.com/water ... alculator/

16 US gallons is about 64 litres.
allowing a 70 C degree temperature rise to boiling
and 0.2 kw heating element
results in 1566 minutes or over 26 hours. Obviously there would be heat losses from the water surface and the metal sides of the tub.

That would be for mono tubs.

Presumably the flat sides of the tubs would need to be smooth.

This might be feasible.

ray
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#337 Re: PASS 50W single ended mosfet amp.

Post by ratbagp »

Allowing a much lower temperature rise of 20 C would still give 447 minutes or over 7 hours.

ray
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Nick
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#338 Re: PASS 50W single ended mosfet amp.

Post by Nick »

I believe that a lot of houses already have large metal things already connected together with water filled pipes, maybe you could bolt the mosfets to those?
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Michael L
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#339 Re: PASS 50W single ended mosfet amp.

Post by Michael L »

I am reminded of my late Uncle Ron in Ontario. He had a lean-to glasshouse and decided he could make use of the heat in this to help heat his bungalow. Unfortunately the heat pump pulled so much heat out all the plants froze. His other idea to use a dozen or more large water butts to
act as a heat reservoir in a glazed over patio was much more successful.

My other Uncle - retired EE after looking at the circuit on here wrote - 'Not thrilled with this circuit. apart from not completely grepping the opto-coupler bit - it basically offers the same kind of cross-over distortion around the zero point that purists are supposed to abhor in solid-state amps - i.e its not single ended. If you cut out the upper half, and put in an audio output transformer, it might be getting towards a single ended design'....

I pointed him here because a couple of months ago he said he couldn't understand why I was using valves when there were suitably linear SS devices available. It was he who bought me Philips Electronics kits as a teen.
Last edited by Michael L on Wed May 03, 2017 3:32 pm, edited 2 times in total.
SimonC
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#340 Re: PASS 50W single ended mosfet amp.

Post by SimonC »

Nick wrote: Wed May 03, 2017 12:48 pm I believe that a lot of houses already have large metal things already connected together with water filled pipes, maybe you could bolt the mosfets to those?
If you connected these water filled pipes to a circulation pump and a small gas or oil heater then it could also have the added benefit of keeping the mosfets at their normal operating temperature even when the amp is turned off... saves waiting an hour for them to stabilise.
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#341 Re: PASS 50W single ended mosfet amp.

Post by ratbagp »

I don't have pipes going anywhere near where the amps would be placed.

Going back to the calculator, it takes about an hour to raise the temperature by 3 C. Presumably it would take quite some time before the temperature of the tub of water reached an equilibrium where the heat losses offset the 200 watts from the mosfets. Does this mean the mosfets would have trouble stabilizing because they would take so long to warm up?

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pre65
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#342 Re: PASS 50W single ended mosfet amp.

Post by pre65 »

Is there a preferred working temperature for those mosfets ?
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pre65
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#343 Re: PASS 50W single ended mosfet amp.

Post by pre65 »

I've got the Single ended mosfet amps out today and set them up, first time since Owston.

With the cheap (but worthy) preamp + buffer the sound is "striking". :D

Just warming them up to see how they are after a session of my sort of music. Starting with Mantovani. 8)
The only thing necessary for the triumph of evil is for good men to do nothing.

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Mike H
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#344 Re: PASS 50W single ended mosfet amp.

Post by Mike H »

I’m glad you said “your sort of music” :D
 
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#345 Re: PASS 50W single ended mosfet amp.

Post by Ant »

Phil do you have a link to the circuit at all?
Im really happy with the pass f5 and having more poke is appealing
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