Burning Amp BA-3

OK!
I have now installed the Salas reg and it is working through a dummy load being run from a newly installed 25V, 1A encapsulated toroid. I had to re-arrange the power amp internals to get everything in. So far so good but I'm still waiting for the BA-3 mosfets to arrive. I gave up on the separate modules idea because I don't have the space and I did want to keep signal paths as short as possible.
Will I need to run the voltage reg ground to the star ground of the power board power supply?
Im pretty sure the answer will be yes but I would appreciate your comments.
Chris
 
Last edited:
Ex-Moderator R.I.P.
Joined 2005
Will I need to run the voltage reg ground to the star ground of the power board power supply?
Im pretty sure the answer will be yes but I would appreciate your comments.
Chris


power star ground is your speaker, right ?

so I would think your regulated frontend ground connects to chassis
through own thermistor

have to say, I'm not really sure about it

Salas reg sounds interesting
I could 'steal' the reg/supply section from a couple of boards I have from symmetric B1 project GB
have thought about it, but I don't know if its suited fore this voltage
remember someone having pretty hot mosfets
and my trafo is 2x22Vac
maybe good heatsinks will do the trick
 
power star ground is your speaker, right ?
I don't think so. Power star ground should originate with the supply.

so I would think your regulated frontend ground connects to chassis
through own thermistor

have to say, I'm not really sure about it
You should never make the chassis a conductor in terms of star ground connections. The chassis should be entirely optional in terms of the circuit. In fact, the biggest reason to ground the chassis is for safety, so that any dangerous voltage errors will short to the chassis and trip a circuit breaker rather than stop your heart. In that sense, chassis ground should be independent of power star ground, and thus should connect to the third wire on your power input cable - the green wire known as safety ground.

An important secondary function of the chassis is to serve as a Faraday shield for your electronics, but don't let that important function tempt you into violating safety grounding standards. The chassis should still serve as a perfectly functional shield even if it isn't part of the power star ground at all. In fact, I believe you could put 48V DC on the chassis and it would be just as effective as a Faraday shield as any other voltage such as "0V" (keep in mind that there really is no such thing as 0V, because each house on your street has a different ground potential depending upon the amount of current flowing in your neighborhood to each home from the power grid source).
 
The PSU Zero Volts should connect to the Main Audio Ground (MAG) via ONE connection. This is usually a wire to carry the power ground currents back to the capacitors.
One does not want the charging circuit currents entering the Power Ground and certainly NEVER on the MAG
Ah, so it seems that the output of the PSU should connect to a star ground where everything else connects from there. The PSU input ground should not connect to this star ground except indirectly through the PSU itself.

It also seems that the "speaker" is not the star ground, unless I'm still missing something.

Any comments on the chassis? ... particularly with regard to star ground and safety ground, etc.
 
Official Court Jester
Joined 2003
Paid Member
you have plenty of highres pics of FW amps on 6moons site

also - you have plenty of pdf files on FW site , almost all of them having schm of common FW PSU , which is extremely well and informative , regarding physical layout .

connecting these pictures with these schematics - in your brain - will give you much more benefits than simply reading answers on your questions

all questions and answers are just parts of broader picture

off course , except in case when answer is 42

:clown:
 
Last edited:
My scheduled BA modular setup.
 

Attachments

  • AMP Design.jpg
    AMP Design.jpg
    130.4 KB · Views: 686
Not sure that we have an exact answer here but at present my star gound is from the output ground of the main power supply and everything sounds good. That is connected to the chassis via a thermistor, as Nelson suggested, for safety (mains outage possibility from the circuit) and to eliminate hum (thermistor). That is my understanding.

I may not connect the BiB reg yet as it is running too hot at present for two of the heatsinks. This could be due to the voltage diff between the transformer and the output being too high. The current mosfets on the BiB are running just fine with respect to temp.
Chris
 
Ex-Moderator R.I.P.
Joined 2005
hmm, I would consider connecting frontend ground to power amp board
and then only there, ofcourse

genuine star ground is a special 'theory' where every ground connection goes directly to the same point, thus called star ground

its just not very practical

look at your ground connections like branches on a tree

so, what you have in reality is multiple star grounds, connected to each other
 
hmm, I would consider connecting frontend ground to power amp board
and then only there, ofcourse

The front end has to have a connection with the ground of the regulated power supply. This leaves (looking at the BA-3 circuit board) a ground connection for the signal input (I assume). This leaves the ground of the power supply for the power output section not connected to the BA-3 front end at all. This is why I wanted to connect the regulated ground to the main power supply ground.
Chris
 
Ex-Moderator R.I.P.
Joined 2005
depends on where and how you connect signal ground

thicker wire may be needed

I choose the shorter more convenient route

like Andrew suggested, it is also possible to make practical use of the the 'negative' speaker terminal
either by a snall copper plate mounted, etc
or just using a thick solid core wire between the speaker terminal and one other point
and place every other needed ground connects along this thick copper wire

one 'could' connect all grounds to amp board ground, but it tends to get messy, and not very practical

personally I choose the shorter and least noise plagued route fore the ground wire
in the old days the midpoint of big power supply caps was often used
but not done that way so much anymore

like said, if taken all parts of the whole setup and their individul ground connections into consideration, it looks like this anyway

basicly, the biggest issue is to determine where you need heavy ground connection, meaning thick wire
 

Attachments

  • o.png
    o.png
    12 KB · Views: 607
Star grounding is always practical and preferable. This is a dual mono Hiraga 30W Class A. It has one central zero point per channel, where all grounds meet except of the the input grounds. Both star groundings are connected to the chassis via thermistors.

It is dead silent.:)




hmm, I would consider connecting frontend ground to power amp board
and then only there, ofcourse

genuine star ground is a special 'theory' where every ground connection goes directly to the same point, thus called star ground

its just not very practical

look at your ground connections like branches on a tree

so, what you have in reality is multiple star grounds, connected to each other
 

Attachments

  • Horn 011.jpg
    Horn 011.jpg
    715.8 KB · Views: 632
  • Horn 012.jpg
    Horn 012.jpg
    561.5 KB · Views: 590
Ex-Moderator R.I.P.
Joined 2005
nice one

you still have two star grounds in each channel
one on amp board, and one on power supply

with this especially short distance between power supply ground and amp board ground like yours, I don't think it matters much how you do it
its basicly similar to a very big 'on-board' supply
 
Ex-Moderator R.I.P.
Joined 2005
The front end has to have a connection with the ground of the regulated power supply.
Chris

hmm, are you taking power from output amp trafo, or using smaller seperate trafo fore regulated frontend supply ?

but basicly, its a relation of how much current the actual curcuit draws, and how thick the wire is

multiple units could cause problems tho
I would claim that if connection between negative speaker terminal and amp board ground is used fore all ground connections, then it would be very safe, and hard to mess up

preferably placing the connecting grounds closer to amp board rather than speaker terminal, ofcourse

in other words
you have two possible BIG 'ground strings'
either the one between big power supply and amp board
or the 'ground string' between amp board and speaker terminal
 
Don't understand what you mean. There is only one star grounding per amp at the power supply. Only the input grounds pass the amp boards. I do practice this since about thirty years in all my audio equipment - preamps, filters, power amps - and it has always been working perfectly.:)



nice one

you still have two star grounds in each channel
one on amp board, and one on power supply

with this especially short distance between power supply ground and amp board ground like yours, I don't think it matters much how you do it
its basicly similar to a very big 'on-board' supply
 
Ex-Moderator R.I.P.
Joined 2005
I do practice this since about thirty years in all my audio equipment - preamps, filters, power amps - and it has always been working perfectly.:)

ofcourse it works
I have built all older amps this way too

but when you start to build two different amps into one box, and each having their own seperate supply, the it could get a bit more tricky

btw, genuine star ground means that every gound connection in the whole amp curcuit all meet in one and the same point, on the amp board

the way you show it has always been common practice, and used fore ages, long before the word star ground was invented
essentially 'star ground' relates to how the amp board layout and its curcuit is designed

as far as I know, but maybe I'm wrong

like I said, it will always be multiple star grounds connected to one string, no matter what
the only choise you have is to choose which goes where
and each can have only one connection
but if you begin to look at it like one single star ground, that's where the trouble starts
 

Attachments

  • o.png
    o.png
    12 KB · Views: 604
I still don't understand. There are two separate amps in one box with separate supplies each = dual mono.



ofcourse it works
I have built all older amps this way too

but when you start to build two different amps into one box, and each having their own seperate supply, the it could get a bit more tricky

btw, genuine star ground means that every gound connection in the whole amp curcuit all meet in one and the same point, on the amp board

the way you show it has always been common practice, and used fore ages, long before the word star ground was invented
essentially 'star ground' relates to how the amp board layout and its curcuit is designed

as far as I know, but maybe I'm wrong

like I said, it will always be multiple star grounds connected to one string, no matter what
but if you begin to look at it like one single star ground, that's where the trouble starts