Hi guys!
I will soon have the My_Ref Evc.C pcb done. I am now searching for a solution for the power source.
I would have access to one of those, (the LCA), power supply for the alimentation part, and cheap. Do you think it would fit? It is an LAMBDA industrial regulated power supply, capable of 2x24v secondary.
Also, I have started to read the MyRef thread to find what is the correct way for the power source, but there's way too much info.
Anyone could tell me clearly what is that design requirering as transfo or PSU?
Thanks a lot!
Jordan
I will soon have the My_Ref Evc.C pcb done. I am now searching for a solution for the power source.
I would have access to one of those, (the LCA), power supply for the alimentation part, and cheap. Do you think it would fit? It is an LAMBDA industrial regulated power supply, capable of 2x24v secondary.
Also, I have started to read the MyRef thread to find what is the correct way for the power source, but there's way too much info.
Anyone could tell me clearly what is that design requirering as transfo or PSU?
Thanks a lot!
Jordan
Yes I made my own, based on the Twisted Pear's site PCB.
So, for the MyRef Rev.C, all I would need is a 24v secondary transfo? Does it absolutely have to be 24v? And what is the seggested primary VA ?
Sorry about the noobness of the questions, but I searched a lot, and found no clear answer...
Regards,
Jordan
So, for the MyRef Rev.C, all I would need is a 24v secondary transfo? Does it absolutely have to be 24v? And what is the seggested primary VA ?
Sorry about the noobness of the questions, but I searched a lot, and found no clear answer...
Regards,
Jordan
again speaking from memory 160VA for seperate trafos, and 250- 300 if you are going to share one...
As long as you don't go to far above or below 35V after rectification you should be ok until you turn the knob almost to the end. so feasably 2 x 22 to 26VAC secondaries could do the trick.
As a recommendation, there are 2 1W 1k resistors, you need bigger wattage for those... try a 2W it gets very hot, also make sure the zener diodes are not flush with PCB so that air can circulate around them.
We just need to wait for Russ or Brian, I am too lazy to go look if their circuit included the PSU bit...
Do you see any transistors in your schematic?
As long as you don't go to far above or below 35V after rectification you should be ok until you turn the knob almost to the end. so feasably 2 x 22 to 26VAC secondaries could do the trick.
As a recommendation, there are 2 1W 1k resistors, you need bigger wattage for those... try a 2W it gets very hot, also make sure the zener diodes are not flush with PCB so that air can circulate around them.
We just need to wait for Russ or Brian, I am too lazy to go look if their circuit included the PSU bit...
Do you see any transistors in your schematic?
Thanks for your info on this! Really appreciated.
Here is the schematics
Jordan
Here is the schematics
An externally hosted image should be here but it was not working when we last tested it.
Jordan
If you etched your boards from the mono block images Russ posted, the power supply is included on each board, along with the speaker protection circuitry.
All you need is a trafo, as mentioned earlier. 24V is the ideal. 25V is fine as well. I actually recommend higher than 160VA per channel. I recently build a couple RevCs using a 250VA for a pair (buyers choice) and the rails do sag quite a bit at higher output levels. 250VA per channel or 400 for a pair would be ideal.
I think Antek (ebay seller) has 400VA 25V torroids for not too much. [EDIT: Doesn;t appear to have any right now]
All you need is a trafo, as mentioned earlier. 24V is the ideal. 25V is fine as well. I actually recommend higher than 160VA per channel. I recently build a couple RevCs using a 250VA for a pair (buyers choice) and the rails do sag quite a bit at higher output levels. 250VA per channel or 400 for a pair would be ideal.
I think Antek (ebay seller) has 400VA 25V torroids for not too much. [EDIT: Doesn;t appear to have any right now]
Correct. Mauro initially drew the RevA as a 2-page schematic. RevC revisions were only to the first page, which is what you see there. The second page, with power supply and protection circuitry is present in the schematic.
You can see the whole thing here: http://www.diyaudio.com/forums/attachment.php?s=&postid=647939&stamp=1116856847
from this post:
http://www.diyaudio.com/forums/showthread.php?postid=647939#post647939
Re: Moved?
Sorry to be off topic but it will be quick..
I got a call from my 9 yr old son who did not want to live with his mom any longer and I did not want to bring him back to Dallas where he would be in day care after school. So I moved back to Lafayette so I could rely on my parents to help me raise him...
Not that I'm a sports fan, but..... After seeing the Cowgirls get WHOOPED by the "aints" I'm kinda glad I wasn't there...
Panelhead said:
Sorry to be off topic but it will be quick..
I got a call from my 9 yr old son who did not want to live with his mom any longer and I did not want to bring him back to Dallas where he would be in day care after school. So I moved back to Lafayette so I could rely on my parents to help me raise him...
Not that I'm a sports fan, but..... After seeing the Cowgirls get WHOOPED by the "aints" I'm kinda glad I wasn't there...
Back on thread
I do not know if larger than 160 per channel is needed for listdning to music. I have used mine with high efficiency speakers at home, but did try one my first with normal multi driver types. This was with a single 7.00 PE transformer of maybe 200 va. Seemed to play fine at levels way beyond what I listen to.
For testing with sine waves and such much larger transformers should help. But actual music has short duration peaks and fairly low average power levels. Steady state response is not the same.
I think that the filter caps provide the energy for the music peaks. With 20,000 ufd per channel on 34 volt rails there is a lot of power stored there.
A power transformer by design should not be able to supply instantanous power surges. It is after all a pair of chokes wound on a common bobbin. The "chokes" want to supply a constant current. This may be the real reason for the purity of a class A circuit. It is the power supply, not the circuit that makes it sound differently than a class AB.
To supply the power to go from a half watt to 50 watts for a climax, the energy almost has to come from the caps. The transformer just recharges the caps.
That is my theory and I am sticking with it.
Talking to Mauro, he recommends a single 300 va transformer for the My_Ref. He feels a stereo supply sounds better. Guess it is the inverted topology he designed into the boards. This has the diodes out of phase between the two channels to reduce current spikes. I wired my Mono's the same way with two transformers, but have no idea if this helps with a mono supply.
George
I do not know if larger than 160 per channel is needed for listdning to music. I have used mine with high efficiency speakers at home, but did try one my first with normal multi driver types. This was with a single 7.00 PE transformer of maybe 200 va. Seemed to play fine at levels way beyond what I listen to.
For testing with sine waves and such much larger transformers should help. But actual music has short duration peaks and fairly low average power levels. Steady state response is not the same.
I think that the filter caps provide the energy for the music peaks. With 20,000 ufd per channel on 34 volt rails there is a lot of power stored there.
A power transformer by design should not be able to supply instantanous power surges. It is after all a pair of chokes wound on a common bobbin. The "chokes" want to supply a constant current. This may be the real reason for the purity of a class A circuit. It is the power supply, not the circuit that makes it sound differently than a class AB.
To supply the power to go from a half watt to 50 watts for a climax, the energy almost has to come from the caps. The transformer just recharges the caps.
That is my theory and I am sticking with it.
Talking to Mauro, he recommends a single 300 va transformer for the My_Ref. He feels a stereo supply sounds better. Guess it is the inverted topology he designed into the boards. This has the diodes out of phase between the two channels to reduce current spikes. I wired my Mono's the same way with two transformers, but have no idea if this helps with a mono supply.
George
I agree with your comments George. Even the RevCs I discussed above with a 250VA trafo sounds fine. The "testing" I did was simply hokking my VOM to the rails and playing music at various levels. The real sagging took place at levels were I was wearing ear muffs anyway. This was also into a 4-ohm load.
I am actually listening to one of them as we speak (shipping Monday) with my Klipsche Quartets (~100db) and they sound fanststic.
As a software guy, I like to design for edge cases. A bigger trafo just makes it bulletproof and suited for all circumstances. I guess I still think about big house parties, even though they are likely a thing of the past for me (my kids will be starting that in about 15 years though, and it would be nice if they could use my "old" RevC amp
).
I am actually listening to one of them as we speak (shipping Monday) with my Klipsche Quartets (~100db) and they sound fanststic.
As a software guy, I like to design for edge cases. A bigger trafo just makes it bulletproof and suited for all circumstances. I guess I still think about big house parties, even though they are likely a thing of the past for me (my kids will be starting that in about 15 years though, and it would be nice if they could use my "old" RevC amp
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