GB,
Those FQA40N25 devices are robust, TO3P and 280W with gfs of 29 and Ciss of 4nF max. This is highly suited to the ALPHA 20 and provided you give sufficient thermal connection to your heatsink it will be outstanding and last decades.
Mind you, if you live in Quebec and use it as a room heater, it will probably last about fifty years because the junction will never get over 50C!!
Thank you Bangla!
Hugh
Those FQA40N25 devices are robust, TO3P and 280W with gfs of 29 and Ciss of 4nF max. This is highly suited to the ALPHA 20 and provided you give sufficient thermal connection to your heatsink it will be outstanding and last decades.
Mind you, if you live in Quebec and use it as a room heater, it will probably last about fifty years because the junction will never get over 50C!!
Thank you Bangla!
Hugh
Last edited:
https://assets.nexperia.com/documents/user-manual/nexperia-engineers-handbook.pdf
When you forget things ! Or in need to ask. Mosfets 😱
Index of /Home/applications/Library/PhD
this is really good imo one tech. related .
I have 2 hours of time to build so i start now.
When you forget things ! Or in need to ask. Mosfets 😱
Index of /Home/applications/Library/PhD
this is really good imo one tech. related .
I have 2 hours of time to build so i start now.
When you forget things
Mr. XR This amp has perfect DC offset tracking with 0mV to 1mV at cold startup all the way to fully warm operation. As you stated.
That would mean one of the lowest measured generally over other amps, so as you built many of these I need data real voltages over components.
Don't refer to look at simulation I need real world measurment. That's not too much asked.
Provide the imd through the focusrite a at 1Wand 10W, also the thd near clipping will be handy
include a few minutes oscilloscope saved file from cold start on to warm.
Mr. XR This amp has perfect DC offset tracking with 0mV to 1mV at cold startup all the way to fully warm operation. As you stated.
That would mean one of the lowest measured generally over other amps, so as you built many of these I need data real voltages over components.
Don't refer to look at simulation I need real world measurment. That's not too much asked.
Provide the imd through the focusrite a at 1Wand 10W, also the thd near clipping will be handy
include a few minutes oscilloscope saved file from cold start on to warm.
Not so good really, well girlfriend came over quess the rest. Heatsink Fisher 200*300*40 black I must go to bed. Regards Toni
It has been a lengthy journey but my ALPHA20 amp is finally singing beautifully in my main system. I’m using an AKSA Lender preamp with low gain daughter boards installed since the ALPHA has lots of gain on its own.
It has .47R source(r131) and .22R sensor(r132) for a lower bias current since its driving pretty easy going speakers (Klipsch Forte I’s, 8ohm, 99dB).
Hypex transformer softstart (cool additional features)—>Transformer is an Antek 400va, 2x20vac —> Vishay rectifiers—>diya universal psu board, which produces +/-27vdc output unloaded. Voltage dips to +/-25vdc when ALPHA boards are connected.
The softstart board has provisions for a low voltage momentary push button on/off switch and thermistor connection for over temperature shutdown just in case there is a fault with the external fan control.
There are Elna Silmic II 10uF input caps installed, I have Mundorf 8.2uF EVO Oils that I was going to swap in, but honestly the Silmics do not sound bad at all. I’ll give some listening time before I make my decision on the swap.
There is a slight bit of hum coming from the speakers if I put my ear to them, but I don’t think it would be audible if less efficient speakers were used.
I think I hit all the main details, now it’s time to enjoy this DIY treat😀
I want to give a big THANKS to Hugh Dean for the ALPHA design, Nelson Pass for the Aleph CCS, JPS for his masterful pcb’s and Xrk for his collaboration and coordinating the group buys (not to mention his endless amplifier building energy!!).
Cheers,
Vunce
It has .47R source(r131) and .22R sensor(r132) for a lower bias current since its driving pretty easy going speakers (Klipsch Forte I’s, 8ohm, 99dB).
Hypex transformer softstart (cool additional features)—>Transformer is an Antek 400va, 2x20vac —> Vishay rectifiers—>diya universal psu board, which produces +/-27vdc output unloaded. Voltage dips to +/-25vdc when ALPHA boards are connected.
The softstart board has provisions for a low voltage momentary push button on/off switch and thermistor connection for over temperature shutdown just in case there is a fault with the external fan control.
There are Elna Silmic II 10uF input caps installed, I have Mundorf 8.2uF EVO Oils that I was going to swap in, but honestly the Silmics do not sound bad at all. I’ll give some listening time before I make my decision on the swap.
There is a slight bit of hum coming from the speakers if I put my ear to them, but I don’t think it would be audible if less efficient speakers were used.
I think I hit all the main details, now it’s time to enjoy this DIY treat😀
I want to give a big THANKS to Hugh Dean for the ALPHA design, Nelson Pass for the Aleph CCS, JPS for his masterful pcb’s and Xrk for his collaboration and coordinating the group buys (not to mention his endless amplifier building energy!!).
Cheers,
Vunce
Attachments
Beautiful looking Alpha you have there Vunce. Must sound fantastic with the Forte’s.
Is the slight hum audible if you disconnect the input RCA’s?
Is the slight hum audible if you disconnect the input RCA’s?
Thanks X!
I’ve got to tell ya, this combo will get my living room to rock concert sound levels 😀
I’ve got to tell ya, this combo will get my living room to rock concert sound levels 😀
Beautiful work, Vunce, and thank you for your gracious comments to all of us in this project. It's been a blast, I have to say......
Enjoy the music!
Hugh
Enjoy the music!
Hugh
Thank you Zman🙂
X,
I played around with the input connectors and a strange result happened.
—When both rca inputs are connected to a preamp a slight buzz/hum is heard at both speakers.
— When the right RCA connector is disconnected from the ALPHA, the left connected channel is dead silent but the disconnected channel still has the slight buzz/hum noise.
— When the left RCA connector is disconnected from the ALPHA, the right connected channel is dead silent but the disconnected channel still has the slight buzz/hum noise.
I used two different preamps and an iPhone as the source and the same results were given.
X,
I played around with the input connectors and a strange result happened.
—When both rca inputs are connected to a preamp a slight buzz/hum is heard at both speakers.
— When the right RCA connector is disconnected from the ALPHA, the left connected channel is dead silent but the disconnected channel still has the slight buzz/hum noise.
— When the left RCA connector is disconnected from the ALPHA, the right connected channel is dead silent but the disconnected channel still has the slight buzz/hum noise.
I used two different preamps and an iPhone as the source and the same results were given.
I appreciate the kind words Gents, thanks🙂
Juntuin,
Could not resist old school Slayer!! And then smoothly transitioned to
Andrea Bocelli. How’s that for diversity 😀
Juntuin,
Could not resist old school Slayer!! And then smoothly transitioned to
Andrea Bocelli. How’s that for diversity 😀
Hugh,
Both alpha boards connect to the psu via paired wires attached to a single faston tab for V+,V-,0v.
So, the power grounds meet together at a single point on the psu board.
Should the input grounds at the rca connectors be wired together and then a single wire return to the alpha board signal ground input and jump to the other alpha signal ground input?
Both alpha boards connect to the psu via paired wires attached to a single faston tab for V+,V-,0v.
So, the power grounds meet together at a single point on the psu board.
Should the input grounds at the rca connectors be wired together and then a single wire return to the alpha board signal ground input and jump to the other alpha signal ground input?
I’ll reconfigure the input wiring tomorrow.
I’d be thrilled if that works and it gets as quiet as when I disconnected one of the inputs.
Thanks Hugh.
I’d be thrilled if that works and it gets as quiet as when I disconnected one of the inputs.
Thanks Hugh.
To be clear you have 10R ground link resistor on pcb signal ground to the one point between smoothing caps I call it diamond, wiring node "
Connect near input sockets Ground Lift 10nF 1k parallel to E metalwork case, heatsink