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Rega IO Amplifier Teardown

DanielT

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2021_11_01_13.51.25.jpg


Seems right.

restorer-john you said But again, they have never really cared a bit about measured performance. Roy Gandy co-founder of Rega seems to verify what you said.

 
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tomtoo

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For a class AB circuit, 1/3 of the maximum power is usually the worst operating condition re thermal stress, because the power dissipation is divided between the external load and output transistors (transistor Pc = Vce*Ic). At maximum power, there is less Vce voltage drop across the output transistors so the thermal load is not that high. 10-15W continuous would be probably the worst scenario for this Rega IO amp.

What makes it even more worse.
 

pma

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What makes it even more worse.
Yes.
Below is an example of an output transistor Pc with respect to input voltage of the class AB amplifier. With output power increased the transistor power Pc decreases above certain input voltage.

Pc_classAB.png

Transistor power vs. amplifier input voltage. Note that highest power dissipation (= area below the curve) is highest at Vin = 1.2V and considerably lower at Vin = 1.8V, though the output power is highest at Vin = 1.8V.
 

MaxBuck

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Lambda

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What this piece of S*** costs 600$ :p While performing significantly worse compared to Beringer "PA" amp with 5 times the power or A generic Aliexpress ClassD or 50-100$
thumb.png



you have got to love this industry.
 

DanielT

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Very interesting read, though the headline is quite misleading.

Gandy is a mechanical engineer. His educational background is reasonable support for designing turntables. Not so much electronic components.

It was probably meant to be a bit provocatively pronounced, that headline. :) The purpose was probably to attract readers when they read the headline. It's just the irony of fate, that headline and what emerges in this thread about Rega IO. So for those who are interested, my tip is to read the whole article.It's mostly about turntables.

It should be added in that article Roy Gandly says:

What Hifi- Measurement or listening - which takes priority?

Roy Gandy-In engineering, measurement is necessary. You cannot make an engineering product without measuring. Being aware of your measuring equipment and what its limitations are is vital.
 
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DSJR

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Roy Gandy doesn't design the electronics and not totally sure he's much involved in the rest of it these days. Their electronic designer loves valves I gather, if that helps any...
 

ta240

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As far as I can tell, there is nothing mounted on them. The power stage is those 5-pin transistors mounted to the bottom of the case. Could it radiate this much heat to the sides? Or are the rectifier diodes adding to it?

What does a thermal shot of the bottom show? If the current photo is from the top, then the heat that is showing in the middle is likely coming through the circuit board from the bottom metal of the case. Which would mean it is much hotter than what shows.

I was surprised to see a number of through-hole transistors in there. Wonder what was special about them that they went through the expense of using them instead of surface mount ones.

Could be they had a lot of them already :)

Whenever people do DIY amps they twist any wires that have AC to reduce the magnetic field. Yet it doesn't seem to be a common practice in a lot of manufactured amps. It seems like it would be even more critical with things crammed in a small space like this. I'm a much bigger fan of the spread out and separated by a wall design like the Akitika. Where only DC crosses the 'wall'. But then it isn't a cute little desktop amp.
GT102AssembledC.jpg


Yes. And I am so grateful that for most of my career in the last 30 years I have been independent of corporate style decisions and orders.
It would be disheartening having marketing tell you what to build, how big to build it, how much to spend and what features it has to have.
 

sarumbear

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I'm a much bigger fan of the spread out and separated by a wall design like the Akitika. Where only DC crosses the 'wall'. But then it isn't a cute little desktop amp.
GT102AssembledC.jpg
Strange that their preamp has no such “wall”. One expects AC bleed to be more of an issue on a low level amplifier. They didn‘t even tried to place the transformer away from the amplifier section.

LookingInsideC.jpg
 

paulio_uno

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While I enjoy reading reviews here, this one is heart breaking. Even more so these days when not wanting to buy chinese brands.
 
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ta240

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Strange that their preamp has no such “wall”. One expects AC bleed to be more of an issue on a low level amplifier. They didn‘t even tried to place the transformer away from the amplifier section.

LookingInsideC.jpg

It is a bit odd. I hadn't looked closely at the preamp as I haven't built one of those. Does less current and lower voltage reduce the magnetic field? It is at least a few inches from the tone/volume board and decently separated from the switching board. And all the AC wires are twisted. I could see where swapping the selector buttons/display board position with the volume/tone/balance board might not be bad. The left side is open for the phono preamp option.

I guess I should start a gofundme page and build one and send it in for testing :)
 

KSTR

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Obviously not layed out by a competent analog engineer.
Well, we just don't know...
Either that what you say, or probably they had a tough time schedule (after that failed 1st attempt with class-D, if I read correctly) and the poor layouter had enough to do with getting to a placing that's half-way reasonable to start actual layout, and probably only on a 2-layer board. An optimized floor planning and instrumentation-style layout sure is possible but this really is a time-comsuming challenge with that level of density.
I'd personally insist on 4-layer (or even 6) and perhaps some vertical daughter boards for the power amp cores and some of the digital stuff, to free board space. Would increase cost and thus likely to be abandoned, though.
 

pseudoid

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It would be disheartening having marketing tell you what to build, how big to build it, how much to spend and what features it has to have.
A wise engineer -- having to contend with marketeers as if they were foot-fungus -- would reply with
"You can pay me now or you can pay me later!" or
"You pay peanuts, you get monkeys!"
I always got the early pay!
 

audio2design

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Well, we just don't know...
Either that what you say, or probably they had a tough time schedule (after that failed 1st attempt with class-D, if I read correctly) and the poor layouter had enough to do with getting to a placing that's half-way reasonable to start actual layout, and probably only on a 2-layer board. An optimized floor planning and instrumentation-style layout sure is possible but this really is a time-comsuming challenge with that level of density.
I'd personally insist on 4-layer (or even 6) and perhaps some vertical daughter boards for the power amp cores and some of the digital stuff, to free board space. Would increase cost and thus likely to be abandoned, though.

I have done quite a few 2 layers boards. It is more work, but it is what it is. Too late to go back and be a doctor or a lawyer. My friends who left EE to be doctors said it was way easier :)

There are aspects of the layout that are just fundamentally wrong. There is no two ways about it, including where the speaker negatives are, which is about as far from a potential star ground point as humanly possible.

The layout to me does not look overly tight. I expect a good number of those resistors could drop down a size, and that can save you a surprisingly large amount of space. There are a few other things I see in the layout that make me question the competency of the person who did it.
 
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