Many power amplifier design need 3 different source voltages. For example, for a 150 watt/channel design, I will want a 600-800 VA transformer with triple outputs for:
1. DC ± 55V for the power output stage with sufficient current rating.
2. Higher voltage, say, DC ± 65V, for the voltage driver state at lower power.
3. Single 12-18V for the speaker protection circuit.
Alternative, a PSU board design that can provide the above from a transform with a single AC ± 40V, center tapped output. There are many PSU boards on the bay, but they do not have multiple output provision.
All the power amplifier that I currently or recently owned have similar triple power supply section. It includes Nikko Alpha 230, Sherwood S-6040CP, Adcom GFA-545.
Are there any hobby market source for such triple output transformer or PSU board?
I posted the same question at Power Supply forum, but did not get any suggestion on the parts source.
1. DC ± 55V for the power output stage with sufficient current rating.
2. Higher voltage, say, DC ± 65V, for the voltage driver state at lower power.
3. Single 12-18V for the speaker protection circuit.
Alternative, a PSU board design that can provide the above from a transform with a single AC ± 40V, center tapped output. There are many PSU boards on the bay, but they do not have multiple output provision.
All the power amplifier that I currently or recently owned have similar triple power supply section. It includes Nikko Alpha 230, Sherwood S-6040CP, Adcom GFA-545.
Are there any hobby market source for such triple output transformer or PSU board?
I posted the same question at Power Supply forum, but did not get any suggestion on the parts source.
dual 40Vac will give you the high power, high current you require for the main amplifier/s.
You can use a dual 6Vac, or dual 9Vac, auxiliary transformer to generate an extra 10 to 14Volts that can be added on top of the main DC supply.
You can bridge rectify each aux secondary and add the DC directly to the main,
or
You can add the AC, in phase with the main secondaries and then separately rectify that higher voltage.
Once you have your higher DC you can regulate, or capacitor multiply, it to suit the front end stages.
The aux transformer probably only needs to be 5VA to 10VA
If you choose an isolated speaker protection circuit, you can operate that direct from one of the elevated secondaries. But not many circuits would suit this.
So maybe easier to buy a second aux transformer (3VA 9Vac), or add a low voltage winding to the toroid.
No help in the other Thread because of your intransigence
You can use a dual 6Vac, or dual 9Vac, auxiliary transformer to generate an extra 10 to 14Volts that can be added on top of the main DC supply.
You can bridge rectify each aux secondary and add the DC directly to the main,
or
You can add the AC, in phase with the main secondaries and then separately rectify that higher voltage.
Once you have your higher DC you can regulate, or capacitor multiply, it to suit the front end stages.
The aux transformer probably only needs to be 5VA to 10VA
If you choose an isolated speaker protection circuit, you can operate that direct from one of the elevated secondaries. But not many circuits would suit this.
So maybe easier to buy a second aux transformer (3VA 9Vac), or add a low voltage winding to the toroid.
No help in the other Thread because of your intransigence
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Andrew, I agree that it is a perfectly workable scheme to use 3 transformers. But when I look inside or the schematics of the Nikko Alpha 230, Sherwood S-6040CP, Adcom GFA-545, it is so much neater to have one transformer. It seems to be a common practice by commercial power audio amp manufacturers. How come the DIY did not pick it up?
I am puzzled that no hobby parts house approaches the OEM transformer maker to market those. It should be cheaper than 3 separate transformers.
It can also be done with the PSU board using voltage doubler and drop down circuit. Only the current stage needs high power/current supply.
I really appreciate you taking the time to reply.
Because OEMs have their transformers wound to spec for them. They don't buy off the shelf transformers. Nikko or whoever is unlikely to make an extra run of the parts to export to US retailers. The transformer maker would in most cases not be able to sell parts Nikko specified, in that those specs are proprietary information.
The DIY is a tiny subset of electronics, and this particular application is yet a tinier still portion of that.
The DIY is a tiny subset of electronics, and this particular application is yet a tinier still portion of that.
You are right. Most power toroidal transformer in the DIY market come from "CNC mill router" motor drive surplus. Once a while, I can find a "removed from power amp" that might get the dual output as this on the bay.
Power Toroidal Transformer for Audio Amp & CNC 230 AC 80 90 DC SUPPLY 115 40 45 | eBay
which, according to the seller, has a 230V primary.
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