Also the BOM specs for the chip PSU say 200-500VA. Other than the cost what would be the advantage and disadvantage to the two extremes. Also the rating "VA", does that not mean "amp volts" would that not be the same as watts?
Sorry for the beginner questions, I'm not an electrical engineer, my only saving grace is that I'm a very talented carpenter with access to exotic woods, metals and plastics and the tools required to turn them in to amazing enclosures, cases and cabinets. So my cases will look stellar , to bad I'm not sure of what is going to happen inside.
Sorry for the beginner questions, I'm not an electrical engineer, my only saving grace is that I'm a very talented carpenter with access to exotic woods, metals and plastics and the tools required to turn them in to amazing enclosures, cases and cabinets. So my cases will look stellar , to bad I'm not sure of what is going to happen inside.
Those are the ones I speced for mine. I am just a noob myself but I do know my way around a soldering iron and this seems like a very straight forward build. The nice thing is there are no adjustments or other fidly stuff to do. I am adding a pot and a switch and making a nice setup for my office at work.
As far as the VA, I cannot put it into technical terms but I think of it terms of what I am going to do with it. I know I want enough power in reserve so as not to push it, but I am not going to be playing it loud and am driving a moderately efficient speaker so the middle of the rating range seemed good to me. There is also a good sized cap in the PS.
Hope I did not add to the confusion.
As far as the VA, I cannot put it into technical terms but I think of it terms of what I am going to do with it. I know I want enough power in reserve so as not to push it, but I am not going to be playing it loud and am driving a moderately efficient speaker so the middle of the rating range seemed good to me. There is also a good sized cap in the PS.
Hope I did not add to the confusion.
I'm a noob too as far as these projects go, but I'm a senior in EE so there are some things that i do know.
VA is not = to Watts. They are not equivalent. They have the same units yes, but they are not the same. The transformers are rated in VA, complex power or apparent power known as S. S = Q + P, where P is power in Watts, Q is VAR, Volt Amp Reactive. The Q comes from complex loads, such as capacitors and inductors, the P from purely resistive loads. So when an amp is rated at 200 Watts, and you try and use a 200VA transformer, it will not supply sufficient power to the amplifier. This is because the transformer has a large inductance and is outputting complex power itself.
There's a lot of information about this topic on this site.
Chip amp power supply- a beginners guide
http://www.diyaudio.com/forums/showthread.php?s=&threadid=128561&highlight=
and the guide, included in the thread above.
http://myweb.tiscali.co.uk/nuukspot/decdun/gainclone_psu.html
With all that said, I plan to over build my PS and use a 500-600VA transformer. This will guarantee adequate power delivery, and it will be easily adapted to other projects.
VA is not = to Watts. They are not equivalent. They have the same units yes, but they are not the same. The transformers are rated in VA, complex power or apparent power known as S. S = Q + P, where P is power in Watts, Q is VAR, Volt Amp Reactive. The Q comes from complex loads, such as capacitors and inductors, the P from purely resistive loads. So when an amp is rated at 200 Watts, and you try and use a 200VA transformer, it will not supply sufficient power to the amplifier. This is because the transformer has a large inductance and is outputting complex power itself.
There's a lot of information about this topic on this site.
Chip amp power supply- a beginners guide
http://www.diyaudio.com/forums/showthread.php?s=&threadid=128561&highlight=
and the guide, included in the thread above.
http://myweb.tiscali.co.uk/nuukspot/decdun/gainclone_psu.html
With all that said, I plan to over build my PS and use a 500-600VA transformer. This will guarantee adequate power delivery, and it will be easily adapted to other projects.
I see a lot of the other designs for chip amps have separate power supply boards. What would be the advantage and disadvantage of the different designs? Is this PSU "snubberized"? If so which components make it so, if not, can that feature be added? Would that have to be done on the chip PSU and the tube PSU?
Sorry, but I'm just a stupid carpenter.
Sorry, but I'm just a stupid carpenter.
There is some good info on this topic here at Decibel Dungeon
There are plus's and minus's to both issues. I believe if I read the schematic correctly the PS for the chip has "snubber" caps in place. Look at the rectifier section for the chip PS you will see the caps surrounding the rectifiers, there are four for each side so a total of eight.
The two nice things about this amp for me is the tube buffer and the all on one board build. It's all you need with the exception of some hardware and some trafos, a pot and switch, if your making an integrated like me.
There are plus's and minus's to both issues. I believe if I read the schematic correctly the PS for the chip has "snubber" caps in place. Look at the rectifier section for the chip PS you will see the caps surrounding the rectifiers, there are four for each side so a total of eight.
The two nice things about this amp for me is the tube buffer and the all on one board build. It's all you need with the exception of some hardware and some trafos, a pot and switch, if your making an integrated like me.
The PCB company are on chinese new year at the moment i belive, so my order is still at there end. I asked if i could make a minor ajustment without effecting the lead time, and they said that was okay. So, i have changed the power supply to a more simple CRC type, and used diode arrays to save space and give a more tidy board. The BOM will be updated shortly. I reccomend using 22,000uf caps for C9 and C10 and somthing like 6,000uf caps for C11 and C12. The resistor bank is an option that you may wish to take, but i would reccomend this for stabilty. As you can see, the PSU has been re routed, i belive this to have a positive impact on the overall design.
You may find the new design here
You may find the new design here
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.