..... @Lee Knatta ground plaine connect smal devices like resistors , capacitors ,transistors and daisy chain power gnd like elyt capacitor and large 10.000uF/100v . I whish to draw an universal board to be avaible also like single side board for home made .I can not afford to buy me a circuit so as to make it home.Another PCB picture attached .
Alex .
I still don't understand what's the grounding concept.
Is there anything else than the 10nF, 100uF/100V and 10.000uF/100V capacitors connected to the groundplane?
What's the point to connect some decoupling caps from same net to the plane and some to the crappy daisy chain ground?
Signal input ground is connected to the plane. Doesn't make sense since you have nasty currents there from decoupling caps. Other decoupling caps are connected to daisy chain ground. Doesn't make sense.
I miss some CONCEPT that makes sense.
The way ground is connected now there's no option to either have a single layer DIY board or a double layer board anyway. You can't have it all. You can design a good two layer board or a single layer board, not both in one board.
Another thing: What's the point having ground fill underneath all the small signal circuits? The plane there is everything but continuous and thus return current can't flow there anyway. The planes only purpose is to add parasitic capacitance to all the traces above. Maybe not an issue but in my opinion the plane is no good there.
My idea:
Use the plane for all power ground and use a separate star ground for all sensitive circuits. Don't mix.
Design a good board using two layers and really use the two layers, not only flood and nothing connected to it. Design another DIY single layer board with all shortcomings associated with such a board like the huge loops you created already despite having two layers at hand.
Btw: I still miss thermals in the latest design.
Regards,
Lee
I still don't understand what's the grounding concept.
I miss some CONCEPT that makes sense.
Another thing: What's the point having ground fill underneath all the small signal circuits? The plane there is everything but continuous and thus return current can't flow there anyway. The planes only purpose is to add parasitic capacitance to all the traces above. Maybe not an issue but in my opinion the plane is no good there.
My idea:
Use the plane for all power ground and use a separate star ground for all sensitive circuits. Don't mix.
Regards,
Lee
The plane would most likely be "antenna like" as well , absorbing stray RF from various sources.
A full split .... separate voltage stage / current stage grounding and supplies with only regulated DC going anywhere near the input stage. What I did on my latest build necessitates using a CRO to detect any "garbage" on either the rails or the input stage ground.(there is NONE) This is DIY , why not do that here ?
Unless the "concept" is to have errata in an amp.
OS
Good design practice would dictate seperate grounds (or planes) for power and signal. Keeping ac fields away from the input should also be considered important (common sense).
Just because Goldmund did it that way............
Here you have a chance to improve the original (not even talking about circuitry) and .........just boggles the mind.
Jam
Just because Goldmund did it that way............
Here you have a chance to improve the original (not even talking about circuitry) and .........just boggles the mind.
Jam
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I believe that the baby Aksa schematics has a very very good solution for separating the grounds.. here the signal gnd.. is simply kept away from pollution by lifting it With a small resistor..in the schematics it's 10 ohm.s but it could be as low as 0.22.. or maybe even lower...It must also be taken at the transformer center-tap.. that is the absolute gnd.....first and lowest impedance is the output power gnd...then the signal gnd..with a little higher impedance...to keep the return path for the speaker current clean...and out of the low signal area of the amplifier...
The chassis is grounded to the gnd of the power input...also via a small resistor (like 50 ohm)...just to keep static from building up...
The chassis is grounded to the gnd of the power input...also via a small resistor (like 50 ohm)...just to keep static from building up...
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Everybody does it like that (aksa,dx, symasym). It serves well , but if you scope that point near the resistor while driving a difficult load you will still see the current pulses.They also use just a single supply AND these are smaller amps. With a totally separate supply , you would use the CT of the secondary trafo for the signal ground , which should not have any pulses "pollution" considering the voltage stages draw little current. You could still use the resistor (I do, 10R) between that "clean" ground and the signal ground. This really works , I am left with just the junction noise of my differentials. I researched how national semi made their test boards for both BJT and MOSFET OPS's which confirmed this method as valid. My chassis ground is connected to the main CT across a 22R/ 1w resistor , this was also validated by national's application notes.
OS
When using a separate transformer for the voltage stage.. then how do you tie the two gnd's together...i mean there can be several volts between the two center taps... transformers are not perfect....do you use a small resistor or just jam them together at the main supply board...
The 2 CT's plug in at different points of the supply board. the small one is attached to the "clean" side of the main PS board through a resistor . A small coil (actually a low value inductor) also separate the 2 CT's. If used for a single trafo the two grounds are still separated by the small inductor , each "side" having 4 large capacitors. Speaker return currents and onboard OPS decoupling capacitor charging currents are also returned to the "dirty" side of the PS board.
OS
I checked out the chassis on
Audio Catalog .
They are very nice, but I plan to try to use the Goldmund's mechanical grounding strategy. This requires the transformers be located in the front of the amp and the output stage at the rear. Can anyone recommend a chassis that supports this layout?
Audio Catalog .
They are very nice, but I plan to try to use the Goldmund's mechanical grounding strategy. This requires the transformers be located in the front of the amp and the output stage at the rear. Can anyone recommend a chassis that supports this layout?
Hi Alex, great work as usual! I've been checking the board very carefully and found a few small mistakes. I would like to ask everyone for their help in checking over the board against the original schematic, please see attachment bellow. Here is what I found so far:
1.) There should be a speaker out - (negative) terminal piece of circuit track/tab on the bottom of the PCB board. This should be right next to the + (positive) speaker out. On the top ground plane side of the board, there should be a heat pad.
2.) There should be a protected speaker out - (negative) terminal piece of circuit track/tab on the bottom of the PCB board. This should be right next to the + (positive) protected speaker out. On the top ground plane side of the board, there should be a heat pad.
3.) 2 Jumpers from 100Rs to BSS71/BSS74s emiters should be circuit tracks on the top ground plane side of the board.
4.) C11 (100uF) capacitor should have the - grounded, the drawing of the capacitor should be reversed.
5.) C8 (100uF) capacitor should have the + grounded, the drawing of +/- should be reversed.
6.) R9 (100K) should be connected to ground.
7.) Picture of +/- on C16 (470uF) should be flipped.
8.) Picture of +/- on C15 (220uF) should be flipped.
9.) Picture of +/- on C14 (470uF) should be flipped.
10.) Picture of +/- on C9 (470uF) should be flipped.
11.) Picture of +/- on C19 (470uF) should be flipped.
12.) Picture of +/- on C18 (220uF) should be flipped.
13.) Picture of +/- on C17 (470uF) should be flipped.
14.) Picture of +/- on C12 (470uF) should be flipped.
15.) Jumper form -80VDC to protection circuit should be a circuit trace on the top ground plane side of the board.
16.) All ground points should have thermal heat pads on the top ground plane side of the board.
17.) There are at least 2 resistors missing from the protection circuit. Some resistors are also mislabeled and some traces connected wrong. It's too difficult to explain everything in words. Alex, can you please look this circuit over and compare it to the original schematic. I've attached a picture below:
I've been checking the board very carefully and found a few small mistakes. I would like to ask everyone for their help in checking over the board against the original schematic, please see attachment bellow. Here is what I found so far:1.) There should be a speaker out - (negative) terminal piece of circuit track/tab on the bottom of the PCB board. This should be right next to the + (positive) speaker out. On the top ground plane side of the board, there should be a heat pad.
2.) There should be a protected speaker out - (negative) terminal piece of circuit track/tab on the bottom of the PCB board. This should be right next to the + (positive) protected speaker out. On the top ground plane side of the board, there should be a heat pad.
3.) 2 Jumpers from 100Rs to BSS71/BSS74s emiters should be circuit tracks on the top ground plane side of the board.
4.) C11 (100uF) capacitor should have the - grounded, the drawing of the capacitor should be reversed.
5.) C8 (100uF) capacitor should have the + grounded, the drawing of +/- should be reversed.
6.) R9 (100K) should be connected to ground.
7.) Picture of +/- on C16 (470uF) should be flipped.
8.) Picture of +/- on C15 (220uF) should be flipped.
9.) Picture of +/- on C14 (470uF) should be flipped.
10.) Picture of +/- on C9 (470uF) should be flipped.
11.) Picture of +/- on C19 (470uF) should be flipped.
12.) Picture of +/- on C18 (220uF) should be flipped.
13.) Picture of +/- on C17 (470uF) should be flipped.
14.) Picture of +/- on C12 (470uF) should be flipped.
15.) Jumper form -80VDC to protection circuit should be a circuit trace on the top ground plane side of the board.
16.) All ground points should have thermal heat pads on the top ground plane side of the board.
17.) There are at least 2 resistors missing from the protection circuit. Some resistors are also mislabeled and some traces connected wrong. It's too difficult to explain everything in words. Alex, can you please look this circuit over and compare it to the original schematic. I've attached a picture below:
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Capasitors voltage
Nagys
Assume that I go for a +-/60 VAC transformer:
C8/ C11
C9/ C12
C14/ C17
C15/ C18
C16/ C19
Will 63V types be "safe" enough?
What about 80 V?
C31/32 and C34/35: 80 V ok, or must it be 100 V?
Resistors: 0,25 W metal film??
2-4 W types: You have recommended Mills. Where to buy??.
Eivind Stillingen
Nagys
Assume that I go for a +-/60 VAC transformer:
C8/ C11
C9/ C12
C14/ C17
C15/ C18
C16/ C19
Will 63V types be "safe" enough?
What about 80 V?
C31/32 and C34/35: 80 V ok, or must it be 100 V?
Resistors: 0,25 W metal film??
2-4 W types: You have recommended Mills. Where to buy??.
Eivind Stillingen
there is no such thing
+/- means rectified DC
2x 40Vac trafo results in +/-56Vdc rails
63V supply caps will be ok
2x 50Vac, +/-70Vdc
80V caps needed
you need to know a bit more than just simple common basics to safely handle this design
experience with startup and setup procedures is required
if you are not enough experienced, do not dispare
there are other amp designs found on this forum that will be equally good, or better
this may be a good amp
but it is wrong if you belive its the best amp ever made
Liliya - Yes, you can use 63V capacitors. Yes, the resistors are .25 watt metal film. Mills resistors you can buy here: Parts ConneXion - The authority on hi-fi DIY parts and components
Capasitors voltage
Nagys/tinitus/msmart2b
Thank you for answering me about the capacitors in Golmund clone.
In # 854 I wrote: "Assume I go for a +-60 VAC transformer". Of course you are right "tinitus", there is no such thing. What I should have wrote was 2x60 VAC.
I do have on my hand two 1000VA transformers(used) 2x70VAC. They are "open" types, so it is possible to unwind down to 2x60 VAC(yes, Nagys, I know you have said that 1000VA is overkill, but I have got a very reasonible price) .
I will go for them in two separate cabinets ( two mono amplifiers)
Conclusion:
I have to go for 100VDC types for C31/32 and C34/35.
All the other capasitors I mentioned in # 854 can be 63V or 80 V types.
I will go for Elna and Phillips.
Tinitus: Dont worry about my skills as a DIY builder. Little in theory, but lot
of experience in practical building.
Eivind Stillingen
Nagys/tinitus/msmart2b
Thank you for answering me about the capacitors in Golmund clone.
In # 854 I wrote: "Assume I go for a +-60 VAC transformer". Of course you are right "tinitus", there is no such thing. What I should have wrote was 2x60 VAC.
I do have on my hand two 1000VA transformers(used) 2x70VAC. They are "open" types, so it is possible to unwind down to 2x60 VAC(yes, Nagys, I know you have said that 1000VA is overkill, but I have got a very reasonible price) .
I will go for them in two separate cabinets ( two mono amplifiers)
Conclusion:
I have to go for 100VDC types for C31/32 and C34/35.
All the other capasitors I mentioned in # 854 can be 63V or 80 V types.
I will go for Elna and Phillips.
Tinitus: Dont worry about my skills as a DIY builder. Little in theory, but lot
of experience in practical building.
Eivind Stillingen
