Max power at 6 Ohm:
---------
At 4.7 Vrms input ( +- 6.6 Volt peak )
Ouput Power will be 3.6 Watt RMS into 6 Ohm.
Pure Class A Watts!
You find this figure low?
You will be surprised how much sound you can get
from 3.6 W pure Class A ....
To get 4.7 Vrms input,
we can put a good audio OP-Amp in front of this OTA.
Gain of this OP-Amp can be like 4-10 ( +6 to +10dB).
If you already have a preamp, you may not need any voltage gain,
but can feed this CLASS A MOSFET SE (single end)
directly from preamp output.
.......................................................................................
This amplifier will be a very good first amplifier project
for anyone starting to get into diy audio.
.......................................................................................
😎 😎
---------
At 4.7 Vrms input ( +- 6.6 Volt peak )
Ouput Power will be 3.6 Watt RMS into 6 Ohm.
Pure Class A Watts!
You find this figure low?
You will be surprised how much sound you can get
from 3.6 W pure Class A ....
To get 4.7 Vrms input,
we can put a good audio OP-Amp in front of this OTA.
Gain of this OP-Amp can be like 4-10 ( +6 to +10dB).
If you already have a preamp, you may not need any voltage gain,
but can feed this CLASS A MOSFET SE (single end)
directly from preamp output.
.......................................................................................
This amplifier will be a very good first amplifier project
for anyone starting to get into diy audio.
.......................................................................................
😎 😎
I am sorry and I really don't mean to be rude but I fail to see why this is creating any excitement.
Looks like a simple source follower with voltage divider bias as appears in almost every textbook on basic electronics.
Not easy to drive!
Great for cold climates ;-)
All those caps :-(
cheers
Looks like a simple source follower with voltage divider bias as appears in almost every textbook on basic electronics.
Not easy to drive!
Great for cold climates ;-)
All those caps :-(
cheers
lineup; good too see someone that is getting THE WHOLE POINT AND NOTHING BUT THE POINT. It' textbook, brutally simple, easy to make, easy to understand, easy on the wallet, a good starting point, can be driven from any half-decent source (like a OPA134-better put 470R in series with the output). If you want decent specs from it you can put it inside the op's feedbackloop, but that's not for me. This is not only for beginner's; I think seasoned audiophiles (with sensitive speakers) might also benefit from trying something simple for a change. Forget about the specs and listen to the music for a little while. Relax, have a beer (or a good cabernet) 
... and don't forget to let your hands on girlfriend's b... .... 
, it is listening impression sqr... 😎
, it is listening impression sqr... 😎
power supply
I completly agree wih Lineup about this being a great starter amp with the plus of it sounding good (plus its SE, has few parts and is very simple)
As an amplifier building noob i have one question:
On the schematic for the power supply it states that C5-C7 are 22000-47000uF chassi mounted screw terminal type Caps.
What should C8 be and why 😕
I completly agree wih Lineup about this being a great starter amp with the plus of it sounding good (plus its SE, has few parts and is very simple)
As an amplifier building noob i have one question:
On the schematic for the power supply it states that C5-C7 are 22000-47000uF chassi mounted screw terminal type Caps.
What should C8 be and why 😕
The schematic says 25W at the Q (only one to choose from😉 ) and 35W at the bottom near R8. Where does those figures belong?
Steen🙂
Steen🙂
There is one thing to consider when building this amplifier.
This is how to handle heat.
There will be a power of ~60 Watt,
25 Watt in MOSFET and 35 Watt in RESISTOR.
Some good heatsinking is needed.
These ARCOL power resistors are to be put onto heatsinks.
50 Watt rated like in this page 50 Watt HS50 Series may be a good choice.
RS Components Ltd in UK, sells 5R = 5 Ohm (and also 4.7 and 5.6 Ohm)
for £1.78
This is how to handle heat.
There will be a power of ~60 Watt,
25 Watt in MOSFET and 35 Watt in RESISTOR.
Some good heatsinking is needed.
These ARCOL power resistors are to be put onto heatsinks.
50 Watt rated like in this page 50 Watt HS50 Series may be a good choice.
RS Components Ltd in UK, sells 5R = 5 Ohm (and also 4.7 and 5.6 Ohm)
for £1.78
Thanks, Lineup. So the figures refers to the dissipation at those particular points🙂 Thats not so bad😀 This would make a nice project for a weekend, if one had to kill a couple of hours.
Funny how those simple circuits are so appealing🙂 Very nice.
Steen🙂
Funny how those simple circuits are so appealing🙂 Very nice.
Steen🙂
steenoe said:
Unfortunately I don't have enough time to keep up with everything, so the homepage suffers badly. It's more fun to design/build amps and listen to music 😉 I have little or no html knowledge, so I'm just using Word to generate the page. It would be great if someone knew about a good wesite builder.
This is the resistor I had in mind, but you can use whatever resistor with the right value that can take the heat. A lightbulb might be nice. The caddock is expensive, but sounds rather nice though 😉
Caddock MP9100-5,00-1%
www.elfa.se # 60-620-87
Caddock MP9100-5,00-1%
www.elfa.se # 60-620-87
Attachments
I missed the fact that it was dissipation figures, as Lineup made clear. Thanks.
Thats a very good suggestion, and easy to mount on the heatsink too🙂
Brian Donegan😀
Steen🙂
Upupa Epops said:
I think you have missed something...as the output impedance is 1/GM of the mosfet...are you suggesting that the transconductance of the Mosfet at 2,5 Amp current is only 0,4 S...
I figure it's more like 0,25 Ohm outputimpedance. I just turn away when the S/N ratio gets too low 😉
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