Building Amp

[bazzy]

From memory of what a late TV serviceman told me was he often used an Isolation transformer on appliances because it minimised the risk of electrocution.

In NSW at least I believe no second-hand appliance can be sold unless it's been tested and certified as 'Safe'.

I think you have a moral responsibility at least to ensure whenever you work on 240V appliances they are 'Safe' because you never know where it may end up in the future.

so what about if upon compleating the amplifier (making sure it is safe) I could get it electrically tested like they do with hardware at work?

[ol' boy]

No more dangerous than an electric deep fryer you can buy at any shop.

[hoe]

What specs you need ? Ive probably got a suitable s/h amp here...

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[bazzy]

What specs you need? I've probably got a suitable s/h amp here...

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looking at about 1000w per channel, What have you got?

[hoe]

Couple of mackie m2600 amps, crown + a couple of transistor amps.
Im on perth now, ill post a list sunday.

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[TVguy]

I would still be concerned if it will be used in public places.
Somebody just has to pour a beer(or better straight whiskey) over it, that runs inside, causes strong arcs (we are talking a 2-3kW power supply here) then ignites nearby flammable(polyester is very popular) decoration, premise burns down, lucky everybody got out, but the forensics find that your amp was the source of the fire but nobody saw the guy spilling the booze.

My recommendation is keep DIY at home and parties outside.

+1 nomeat. The liability of using DIY equipment in a public place is not worth the grief.
Whilst audio power amplifiers are not declared articles, they are still subject to ACMA approval as a built product.
Compliance with relevant state regulators would be considered mandatory when used in a public place.

Please refer to AS/NZS 60065:2012, Australian/New Zealand Standard: Audio, video and similar electronic apparatus—Safety requirements (IEC 60065, Ed.7.2 (2011) MOD).
If the mains lead is captured, it must be approved:

Quote:

"Makeshift methods, such as tying the cord into a knot or tying the cord with a string, are not
permitted.
The devices for strain and twist relief shall either be made of insulating material, or have a
fixed covering of insulating material other than natural rubber, if an insulation fault of the cord
may make ACCESSIBLE conductive parts HAZARDOUS LIVE.
For CLASS I apparatus, the arrangement of the TERMINALS for the MAINS supply flexible cord, or
the length of the conductors between the device for strain and twist relief and the TERMINALS,
shall be such that the HAZARDOUS LIVE conductors become taut before the conductor connected
to the PROTECTIVE EARTHING TERMINAL, in case the cord slips out of the device for strain and
twist relief.
Compliance is checked by inspection and by the following test.
The test is made with the type of flexible cord attached to the apparatus.
The apparatus is fitted with its flexible cord, the device for strain and twist relief being
appropriately used. The conductors are introduced into the TERMINALS, and the TERMINAL
screws, if any, are slightly tightened, so that the conductors cannot easily change their
position.
After this preparation, pushing the cord further into the apparatus shall not be possible or shall
cause no hazard in the sense of this standard.
A mark is made on the cord, under strain, near the aperture, and the flexible cord is subjected
100 times to a pull of 40 N for a duration of 1 s each. The pull shall not be applied in jerks.
Immediately afterwards, the cord is subjected for a period of 1 min to a torque of 0,25 Nm.
During the test, the cord shall not be displaced by more than 2 mm, the measurement being
made while the cord is still under strain. The ends of the conductors shall not be noticeably
displaced in the TERMINALS and no damage to the flexible cord shall be caused by the device
for strain and twist relief."

Tread cautiously as the litigation that may follow could envelope you in a world of hurt.
Purchase an approved product with a Regulatory Compliance Mark (RCM) and all risk can be offloaded to the manufacturer / supplier.

[BCNZ]

I am looking at building an amp that is 1000w per channel.

Do you have experience with constructing amps of this power capability?
If not, I suggest you aim for something a little more modest in its output specs.
The reason is that amps which can sustain a kilowatt into 8 or 4 ohms have enormous short circuit current potential.
Not only that, but the power supply rails are usually 100 V DC (or more) each side (so 200 V or more swing) which is more than enough
to make you say f*ck and ouch and bastard and holy mother of a polecat prior to you being toasty fried.
If you get something wrong during testing or operation you will have Chernobyl in your work area - which for your house and you is not a pleasant situation.

If you have experience, then forge ahead and please keep us updated with photos and progress reports.
There are plenty of good kilowatt+ amps on the market, QSC make some really good ones including some which are even more grunty.
I think their biggest one is 4.5 kW into 8 ohms.

As for the legality of building something which is mains powered, I don't know about Aussie regs, but here in NZ you are allowed to work on your own equipment (providing it is not hard-wired into the wall, i.e. it has a removable plug) and that includes building mains operated appliances.

Naturally you'll want to build it in a professional fashion, with proper earthing, lead-dress, appropriate sized cables and mechanical protection for them, power supply protection etc.

Below is the output board for a QSC RMX5050 which is good for about 1100 watts into 8 ohms.
It will give you some idea as to the layout and (relative) complexity of such machines.

[gordon_s1942]

studio1, I think it would be safe to say almost all of the safety standards regarding appliances are the same in both OZ and NZ.

Like near everyone I have made extension leads or repaired or replaced either the plug or socket and I have tried to ensure on such a trivial item that I have done whats needed so no one can be hurt.

[bazzy]

Do you have experience with constructing amps of this power capability?
If not, I suggest you aim for something a little more modest in its output specs.
The reason is that amps which can sustain a kilowatt into 8 or 4 ohms have enormous short circuit current potential.
Not only that but the power supply rails are usually 100 V DC (or more) each side (so 200 V or more swing) which is more than enough
to make you say f*ck and ouch and bastard and holy mother of a polecat before you being toasty fried.
If you get something wrong during testing or operation, you will have Chernobyl in your work area - which for your house and you is not a pleasant situation.

If you have experience, then forge ahead and please keep us updated with photos and progress reports.
There are plenty of good kilowatt+ amps on the market; QSC makes some really good ones including some which are even more grunty.
I think their biggest one is 4.5 kW into 8 ohms.

As for the legality of building something which is mains powered, I don't know about Aussie regs, but here in NZ you are allowed to work on your equipment (providing it is not hard-wired into the wall, i.e. it has a removable plug) and that includes building mains operated appliances.

Naturally, you'll want to build it in a professional fashion, with proper earthing, lead-dress, appropriate sized cables and mechanical protection for them, power supply protection, etc.

Below is the output board for a QSC RMX5050 which is good for about 1100 watts into 8 ohms.
It will give you some idea as to the layout and (relative) complexity of such machines.

Hi Mate

Yes, the design I am looking at can operate up to 110v, I have worked on these amplifiers before and am well aware of the risks they pose.

Unfortunatly for the speaker towers, i am working with an amplifier with 1kw per channel is necessary to drive them. Anything under that will be overloaded and cause issues just as bad.

the design I am working on has voltage protection included in the design as well as balanced audio and soft start etc