Simple Symetrical Amplifier

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Lazy Cat

Lazy Cat

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Joined 2007
SSA BIGBT Basic

Great Alex ! :)

This PCB will enable anyone to check the sound of the SSA BIGBT Basic version. ;)

I will detaily check the PCB and let you know about all remarks soon, latest tomorrow. Thanks again Alex ;)
 

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sng001

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Joined 2009
Nico Ras said:
I added the 3.3 pF FB capacitors only to band limit the amp in case of spurious pick-up from the speaker cables. Some FM tuners 10.7MHz can radiate IF and the amp can still operate at that frequency.

Regards

Nico
Click to expand...

Hi Nico,

You posted this a while ago - Post #320.

Did you change the C12 & C13 from 12pF to 3.3pF?

You also said that you would implement some of the MiiB's changes, can you please post your latest schematics?

I plan to build the SSA with one pair of L-MOSFET running with 38V DC rails.

I will change AlexMM's layout a bit so that I can use 30mm (10000uF/50V) caps.


Best regards, Stanley
 
Lazy Cat

Lazy Cat

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Joined 2007
Joachim Gerhard said:
Alex, so this is now schematic from post 217 ?
Click to expand...

radio said:
Alex mm, well done!
By which schematic this was done PCB?
Regards
Click to expand...

The upper one, from post #401, that is the SSA from my latest listening test. ;)

It is almost the same as from #217, only emitter resistor is added to Vbe multiplier to track tempco more accurately. Otherwise the same sch. ;)
 
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Bigun

Bigun

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diyaudio.com/community/threads/tgm8-an-amplifier-based-on-rod-elliot-p3a.245619/
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AKSA said:
I like your approach, Bigun. Very elegant, and the emitter driver output will have low impedance and drive the output stage very well.

Let's see, base to rail resistor for predriver would be 1K, we could run the driver quiescent at around 30mA, and this means, assuming cascode current is 2mA, the predriver emitter to rail resistor would be 47R. With a Zout at each driver emitter of around 1R, you'd have enough drive to propel the USS Nimitz, and of course nice local feedback around the driver circuit. One change, however; I'd put a 1K resistor from emitter to base on each driver to ensure residual current at all times through the predriver.

Cheers,

Hugh

PS I'm not dead sure of the cascode current, but 2mA seems about right to me.

Hugh
Click to expand...


Thanks Hugh for that input, it does indeed need these things to flesh out the design and it's good to know that you also have some confidence in this version.
 
radio

radio

Banned
Joined 2009
Changes!?

Hi Lazy Cat (Hi Slovenija)!
I have a few questions about this amplifier.
Is it can replace the bias transistor BC550C with BD139 (better is to mount the fridge) or some are needed changes?
For the output transistors can be used ate MJ15003/MJ15004?
In the end, I ask you in a few sentences if you are able to explain how this amplifier?
It will be interesting for electronic amateurs!?
thanks and cheers !
 
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Lazy Cat

Lazy Cat

Member
Joined 2007
radio said:
Hi Lazy Cat (Hi Slovenija)!
I have a few questions about this amplifier.
Is it can replace the bias transistor BC550C with BD139 or some are needed changes?
For the output transistors can be used ate MJ15003/MJ15004?
In the end, I ask you in a few sentences if you are able to explain how this amplifier?
It will be interesting for electronic amateurs!?
thanks and cheers !
Click to expand...

Hi there ;)

I will check both Vbe/temperature curve dependency and if OK, than we could use BD139 because of an easier fixation to the main heatsink. :)

MJ15003/MJ15004 are "strong" enough, have small hFE + gain bandwidth but it would work, though I have never used them in fast CF amp as SSA is. :rolleyes:
 
Lazy Cat

Lazy Cat

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Joined 2007
juma said:
That's what happens when we have a thread with 100 schematics and neither of them has a clear, distinctive name... :eek:
The best we can do now is to refer to them by post number.
Click to expand...

It is basically an educational thread so that's the only way to do it. Maybe you've noticed that when it is the post with schematic published, I put always a different SSA name of the post and the yellow exclamation mark.
 
radio

radio

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Lazy Cat said:
Hi there ;)

I will check both Vbe/temperature curve dependency and if OK, than we could use BD139 because of an easier fixation to the main heatsink. :)

MJ15003/MJ15004 are "strong" enough, have small hFE + gain bandwidth but it would work, though I have never used them in fast CF amp as SSA is. :rolleyes:
Click to expand...

What you propose transistors in TO-3 casse because i have a large refrigerator for this type transistors!
Regards
 
Nico Ras

Nico Ras

Member
Joined 2005
Hi All,

I think there are three "tested" schematics here, the L-MOSFET, Michael's (MiiB) BJT version and Andrej's IGBT version.

If I may suggest that Alex would could start a thread where his PCB layout and the associated "tried" schematics are posted for those who want to build and try this superb design for themselves without having to search 400+ posts, but keep that thread totally uncluttered of comments other than PCB layout comments.

Why I am suggesting Alex if he has the time is that he is the only one that has a schematic and BOM that matches up with a PCB on his computer.

Discussions and new ideas remain here on this thread. Any comments on this suggestion?

Regards

Nico
 
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