Most 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? If not, what is your option?
(Yes, I know that I can use 3 transformers per channel. But I would rather not.)
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? If not, what is your option?
(Yes, I know that I can use 3 transformers per channel. But I would rather not.)
No they don't.
For the higher voltage supply adding a few turns of low current wire to a toroid secondary is an easy option. The protection circuit can be powered from the transformer via potential divider.
May be NOT ALL of them. But some do and I found that to be a good topology for high current output power amplifier. I am not talking high end either.
Can you cite me one that don't use different voltage for voltage and current amp section. I mean higher quality amp, not low end receivers.
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I can provide you with such tranny - we produce custom toroid tranny for audio - just contact me with your detail specification then i'll quote you.
Thank you for your offer. I am looking for reasonable cost, hobbyist type single unit purchase. A special ordered transformer shipped from oversea may be too expensive for me? I am not a manufacturer of audio equipment.
Yes, the shipping cost would be the problem you will have....but we're also in DIY business, most of our customers are DIYers - we are accepting a single tranny order.
anyway, good luck with your search.
Gabe
you don't need to order a custom wound mains transformer.
A normal dual secondary mains transformer will power any power amplifier.
If you decide you want and need other supply voltages you can add them on.
Scott has given you some ideas already.
I have not figured out how I can "add a higher voltage rail" to a toroidal transformer, much less EASILY. A schematic on how to do it will be much appreciated. Besides, the power transformer is a high (relatively speaking) power device. I would not want to change the insulation wrapping that may affect its reliability.
Yes, it is true that a normal dual secondary mains transformer will power any power amplifier, with a adequate VA rating. You do understand the advantage of a multiple output transformer? For any given VA rating of the transformer core, it is a waste to wire the transformer to the voltage amp's (higher) voltage requirement. It requires a bigger VA core to meet the current stage's (higher) current requirement.
I have not figured out how I can "add a higher voltage rail" to a toroidal transformer, much less EASILY. A schematic on how to do it will be much appreciated. Besides, the power transformer is a high (relatively speaking) power device. I would not want to change the insulation wrapping that may affect its reliability.
I am asking for an example of commercial amp that is considered higher quality, but does not use multiple output rail transformer.
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Having looked at your profile I don't understand your difficulty, I suggest googling something like "adding windings to a toroidal transformer" for example.
It is 2 completely different thing.
Yes, it is easy "adding windings to a toroidal transformer" in a signal or low current path. You can find it in any HAM Radio handbook and there is no need to Google.
To modify a 1KVA power transformer to add an additional output is anything but easy. A multiple output power toroidal transformer should be designed from the ground up. We can agree to disagree.
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