I am planning on building a very high power class d amp. Would it be plausible to rectify direct mains? i have got a 270w, 1ohm resistor to prevent a 100000000000A surge when you turn the power on. This could prevent the need for getting a massive transformer.
I live in england so have a 240v RMS power supply with 340v peaks. This would mean that the supply rails would be at +-170V.
A current regulator could also be used to prevent excessive current at turn on.
Rob
I live in england so have a 240v RMS power supply with 340v peaks. This would mean that the supply rails would be at +-170V.
A current regulator could also be used to prevent excessive current at turn on.
Rob
Hardly possible
if you have 340V rails than peak current at 'normal' operation (not hard-start) would be +-21A for 8ohms and +-40A for 4ohms. This may require 3-phase mains.
And Yes
putting 1ohm restricts 80% efficiency for 4ohm speaker. Except you will probably need a varactor and high current chokes for clean enough rails.
For +-170 if your '0' has anything to do with physical earth or ground, than you're dead. A 'cold' wire in mains is often (in older hauses) the same as earthing. (I'm guessing you know about all these things better than me but many may read this thread). Bridge topology eith single rail may be a cure.
If you consider turn-on than it is absolutely OK to use soft start circuit. You may add a 10W transformer for it and a high current relay. That's not a problem. Problems are elsewhere. Fuses... protections... just think how hard it wll be isolate all these 'grounds' being 170V in your case.
ive just realised that the supply would be at +- 340v not 170v as it is 340 above and below neutral. Thats a bit much and i dont think it is worth doing as i would need to be working with high voltage components.
It depends on rectification. If you use only one diode and a cap, than you have +340V, not +-
I assumed this.
I assumed this.
+/- 170V Rails would give you 1800 Watts into 8 Ohms... a little nuts I guess... potentially dangerous too.
330v single rail is what you get. Then you better go with full-bridge. As my 4.5kW project...
Safety issues become quite serious but it is possible with amplifier integrated to sub casing and using 4kV isolation spec line-input transformers(lunhdall, spell?)
woofer element needs also some special attention, consider woofer chassis to be part of live circuitry, ie separate metal grille in front of it etc. Horn/bandbass box desings are probably easiest to design safe so that toughing to element is not possible.
Safety issues become quite serious but it is possible with amplifier integrated to sub casing and using 4kV isolation spec line-input transformers(lunhdall, spell?)
woofer element needs also some special attention, consider woofer chassis to be part of live circuitry, ie separate metal grille in front of it etc. Horn/bandbass box desings are probably easiest to design safe so that toughing to element is not possible.
Hi, actually I am an electrical engineer.
Basically you must protect electric shock as standard equipment. Even you use isolated transformer, leakage current for all equipment are to be considered. Of course if you care this issue.
Use current leakage protection to protect you. All metal shall be earthed. Live parts shall be isolated, including your amp input. Speaker including box that may be in wet must be grounded. Use speaker binding that prevent to be touched. Careful to charged capacitor.
Basically you must protect electric shock as standard equipment. Even you use isolated transformer, leakage current for all equipment are to be considered. Of course if you care this issue.
Use current leakage protection to protect you. All metal shall be earthed. Live parts shall be isolated, including your amp input. Speaker including box that may be in wet must be grounded. Use speaker binding that prevent to be touched. Careful to charged capacitor.
Do NOT use mains directly without a safety transformer!!! I would reccommend a few UcD700 modules in paralelled pairs that you bridge, way safer than trying to build a suicide machine with direct mains feed.
My five cents.
My five cents.
You are right Tekko,
That's why I give suggestion that costly, more expensive than buy isolated PS.
I know also that this forum reject the discussion for direct connection to mains. My suggestion is for people who ready to take serious risks to connect their amp directly to mains at their home.
That's why I give suggestion that costly, more expensive than buy isolated PS.
I know also that this forum reject the discussion for direct connection to mains. My suggestion is for people who ready to take serious risks to connect their amp directly to mains at their home.
Even i'm not this crazy
DON'T DO IT!
You will fry!!!
Especially not at Christmas
Hope to talk to you laterZ
Mad.P
P.S Merry Xmas all
DON'T DO IT!
You will fry!!!
Especially not at Christmas
Hope to talk to you laterZ
Mad.P
P.S Merry Xmas all
I am a little astonished that this has not had some big-time moderator warning attached yet, nevermind being deleted/moved to Texas/locked.
I was reading this and, although going directly to mains is not a great idea, could you run a Balanced AC circuit through the walls(balanced AC is 60v+/- for US vs single ended 110/120v) and plug the powersupply for a UCD 700 directly into the wall taps, along with the rest your equiptment. I know that they sell balanced AC rack units (which contain a very large transformer) and believe that they are available for an in wall installation that are up to code...
i am now certain that this is realy stupid! I never though it would be possible (safely) but i just wanted to see what the opinion was from the forum.
thanks guys
thanks guys
I thought about something similar, but with two transistors in push-pull into a transformer, like in old tube-amps.
What do you think?
What do you think?
kubeek,
I hope your other thread gets attention as long as your intention is to not power it directly from mains.
Every now and then we have to warn members and close threads like this. It's hard for us mods to determine if members have enough experience with this kind of applications. I believe few of us have.
Besides that, we don't want to waste our life for that one big-power project do we?
/Hugo
I hope your other thread gets attention as long as your intention is to not power it directly from mains.
Every now and then we have to warn members and close threads like this. It's hard for us mods to determine if members have enough experience with this kind of applications. I believe few of us have.
Besides that, we don't want to waste our life for that one big-power project do we?
/Hugo
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