Amps - Whats in em and why?

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Geoff.R.G
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Re: Amps - Whats in em and why?

Unread post by Geoff.R.G » Fri Nov 08, 2019 1:00 pm

Lurcher300b wrote:
Fri Nov 08, 2019 12:48 pm
To be fair, I would like to know why they chose four output transistors per channel?
They will have looked at the expected power output required into various loads, then looked at the SOA curves for the output devices, then decide what safety margin they need and base the number of devices on those things.
Most of which information we don't have of course. Being cynical I did wonder whether they had done so for some other obscure reason. Remember my background is in aviation where I would have been questioning the additional weight and power consumption as well as the benefits. I can think of at least one electronic device where dual output devices would have been a real winner, as would more intelligent built in test!

Lurcher300b
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Re: Amps - Whats in em and why?

Unread post by Lurcher300b » Fri Nov 08, 2019 1:20 pm

Well, the SOA information we do have, its printed on the device spec sheets. There is a little additional power consumption as the parallel devices would use more quiescent current than the single pair, but its possible that the weight could be reduces as the multiple devices may spread the heat around the heatsink better allowing a smaller one to be used. Not by much, but its possible. in general its just engineering. The design would have been done to a spec and then the marketing department would have tried to cherry pick facts from the design and try and make them look like features.

Getting 100W out of a single pair of medium power devices (160W is not high) is normally on the edge of whats advisable so two make for a safe life and reliability.

Maybe its something like 2SC6011/2SA2151

https://www.semicon.sanken-ele.co.jp/sk ... _ds_en.pdf

Geoff.R.G
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Re: Amps - Whats in em and why?

Unread post by Geoff.R.G » Fri Nov 08, 2019 3:29 pm

Lurcher300b wrote:
Fri Nov 08, 2019 1:20 pm
Well, the SOA information we do have, its printed on the device spec sheets. There is a little additional power consumption as the parallel devices would use more quiescent current than the single pair, but its possible that the weight could be reduces as the multiple devices may spread the heat around the heatsink better allowing a smaller one to be used. Not by much, but its possible. in general its just engineering. The design would have been done to a spec and then the marketing department would have tried to cherry pick facts from the design and try and make them look like features.

Getting 100W out of a single pair of medium power devices (160W is not high) is normally on the edge of whats advisable so two make for a safe life and reliability.

Maybe its something like 2SC6011/2SA2151

https://www.semicon.sanken-ele.co.jp/sk ... _ds_en.pdf
Thank you for that, I hadn't considered heat distribution, using multiple devices is common in power electronics so I should probably have realised that one. A factor of safety would be on my list of questions and as you say 160W isn't high. The increased quiescent current could be important as some aircraft power systems have little spare capacity, though one would use the full power current in the Electrical Load Analysis. In some load configurations additional quiescent current, with multiple examples of the same piece of equipment installed but inactive, might make for an interesting balancing act.

I now wonder what the OP makes of this?

Lurcher300b
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Re: Amps - Whats in em and why?

Unread post by Lurcher300b » Fri Nov 08, 2019 4:39 pm

I don't know how it is in avionics, but I would expect a lot of power control would be done with switching devices now so thermal management and power handling should be much simpler.

Geoff.R.G
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Re: Amps - Whats in em and why?

Unread post by Geoff.R.G » Fri Nov 08, 2019 6:16 pm

Lurcher300b wrote:
Fri Nov 08, 2019 4:39 pm
I don't know how it is in avionics, but I would expect a lot of power control would be done with switching devices now so thermal management and power handling should be much simpler.
In many cases, yes but you should see the cooling systems for power electronics! The 787 has lots of high voltage DC to make life even more interesting, there is a total of 1000KVA to play with (4 x 250KVA). Software controlled C/Bs are fun too!

_D_S_J_R_
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Re: Amps - Whats in em and why?

Unread post by _D_S_J_R_ » Sat Nov 09, 2019 1:59 pm

I spoke to the sales manager of said product range on Thursday and he told me the signal path is actually quite simple (I have to take his word on it), but there's a lot of 'housekeeping' in there to keep things safe and reliable. He was quite surprised a pic of the innards had been published somewhere as it's a very new model. It 'sounds' just fine and the 'sound' changes with the recordings played through it, so it does the job well enough I reckon.


Daniel Quinn
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Re: Amps - Whats in em and why?

Unread post by Daniel Quinn » Sat Nov 09, 2019 3:31 pm

How do you know what it sounds like.

_D_S_J_R_
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Re: Amps - Whats in em and why?

Unread post by _D_S_J_R_ » Sat Nov 09, 2019 5:26 pm

Daniel Quinn wrote:
Sat Nov 09, 2019 3:31 pm
How do you know what it sounds like.
If that's to me, I spent over three hours listening through one last Thursday evening. It's the new Rega Aethos integrated amp.

valvesRus
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Re: Amps - Whats in em and why?

Unread post by valvesRus » Sat Nov 09, 2019 7:22 pm

_D_S_J_R_ wrote:
Sat Nov 09, 2019 5:26 pm
Daniel Quinn wrote:
Sat Nov 09, 2019 3:31 pm
How do you know what it sounds like.
If that's to me, I spent over three hours listening through one last Thursday evening. It's the new Rega Aethos integrated amp.


This item is not available by Mail Order and can only be purchased in store.

According to several dealers.

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