With the values show in the attachement you have
balanced in and balanced out a gain of 4x
balanced in and unbalanced out a gain of 2x
for people that do not need much gain.....
the values are 150R for R22
and 470R for R23/R24
and I think the distortion might be even lower in simulation....
but I can connect the THD meter only to one output, so there is no cancelation of distortion....
balanced in and balanced out a gain of 4x
balanced in and unbalanced out a gain of 2x
for people that do not need much gain.....
the values are 150R for R22
and 470R for R23/R24
and I think the distortion might be even lower in simulation....
but I can connect the THD meter only to one output, so there is no cancelation of distortion....
Attachments
Here are small knapsack circuits for the BA-3 boards from the diyaudio shop. They allow to switch from one channel balanced mode into stereo unbalanced. They are simply soldered into the holes for the two 100R resistors that lead from the wipers of the 100R pots to ground.
OFF-ON-OFF = balanced, the two 100R resistors are in line, ON-OFF-ON =unbalanced, the two resistors are laid to ground.
OFF-ON-OFF = balanced, the two 100R resistors are in line, ON-OFF-ON =unbalanced, the two resistors are laid to ground.
Attachments
I am thinking about, ok almost decided already, to build the balanced version of the burning amp with the BA-2 output stage.
However I am still unsure if my calculations are ok or not regarding voltage/current/devices and dissipation figures.
Can someone have a look at the picture with the numbers I've come up with and say if they are fine or completely rubbish? To clarify beforehand the amount of Fets are counted for ~20W per device.
However I am still unsure if my calculations are ok or not regarding voltage/current/devices and dissipation figures.
Can someone have a look at the picture with the numbers I've come up with and say if they are fine or completely rubbish? To clarify beforehand the amount of Fets are counted for ~20W per device.
Attachments
Ok so I have read this thread twice now. I get that if you want to go this route that as well as doubling up the FE you also need to double up the output boards.
SO is it as simple as one output board is the speaker out and the other is the speaker return? with out+ from the FE going to D the speaker out output board, and out- going to D on the speaker return output board?
What about the power supplies? separate or shared for the two output boards?
I think I'm going to wimp out more than likely and just build a standard BA3, as I don't have anything with balanced outputs, but the lower distortion and higher power didn't escape my attention
(and I'm imagining that even with a single ended input, those advantages don't go away??)
Tony.
SO is it as simple as one output board is the speaker out and the other is the speaker return? with out+ from the FE going to D the speaker out output board, and out- going to D on the speaker return output board?
What about the power supplies? separate or shared for the two output boards?
I think I'm going to wimp out more than likely and just build a standard BA3, as I don't have anything with balanced outputs, but the lower distortion and higher power didn't escape my attention
(and I'm imagining that even with a single ended input, those advantages don't go away??) Tony.
Buzz this comment from generg worried me. I don't know exactly how to interpret number2. As I will only have unbalanced inputs for the forseeable future that comment worries me
Also I still don't know for certain what I have to do to make it balanced!! apart from buy BIG heatsinks
Tony.
Also I still don't know for certain what I have to do to make it balanced!! apart from buy BIG heatsinks
Tony.
what I can say to the qualities of BBA-3.......
I have a Meridian CD-Player with balanced and unbalanced output....
with BBA-3 the difference between balanced in and unbalanced in is very very big......!
Such a big difference was not to hear with Aleph P and even Pumpkin(g) my favorite pre...
conclusion....... 1. the balanced input of BBA-3 is the best I ever had.
2. the unbalanced input of BBA-3 is the worst I ever
had...
Hi Tony,
what a harsh comment from me..... I try to remember and explain....
If you have one normal BA-3 frontend and pcb from the shop, you go unbalanced in and unbalanced out and it sounds wonderful! Really!
my problem was.... My cd-player sounds better with balanced out so I bought two BA-3 front end boards and used one board with the two circuits for the left and one board with the two circuits for the right channel. But this time I used Nelsons scheme for balanced frontend, connecting both halves on the pcb as advised with the 200R resistor.
So you see I had the input balanced but I used the output unbalanced by shorting the neg. output with a cap against ground because my amp at this time had only unbalanced inputs.
Only for fun I used this balanced constellation also with unbalanced input by shorting the neg. input against ground and in this way it did not sound so good to my ears....
but who builds a balanced in and output device and uses it later only unbalanced in and out?
So I tell you the normal BA-3 fronted with unbalanced in and unbalanced out sounds very very good!
what a harsh comment from me..... I try to remember and explain....
If you have one normal BA-3 frontend and pcb from the shop, you go unbalanced in and unbalanced out and it sounds wonderful! Really!
my problem was.... My cd-player sounds better with balanced out so I bought two BA-3 front end boards and used one board with the two circuits for the left and one board with the two circuits for the right channel. But this time I used Nelsons scheme for balanced frontend, connecting both halves on the pcb as advised with the 200R resistor.
So you see I had the input balanced but I used the output unbalanced by shorting the neg. output with a cap against ground because my amp at this time had only unbalanced inputs.
Only for fun I used this balanced constellation also with unbalanced input by shorting the neg. input against ground and in this way it did not sound so good to my ears....
but who builds a balanced in and output device and uses it later only unbalanced in and out?
So I tell you the normal BA-3 fronted with unbalanced in and unbalanced out sounds very very good!
thanks generg ok that's not what I thought.... I thought you were saying that unblalanced in with balanced out sounded bad (Nelson had earlier said that the circuit could work with unbalanced input).
This is what I would be doing most likely as I have at this stage no sources that can work in balanced mode.
There seemed to be still an advantage using the balanced BA3 even if the source was not, but your comment made me concerned
Tony.
ok that's not what I thought.... I thought you were saying that unblalanced in with balanced out sounded bad (Nelson had earlier said that the circuit could work with unbalanced input). This is what I would be doing most likely as I have at this stage no sources that can work in balanced mode.
There seemed to be still an advantage using the balanced BA3 even if the source was not, but your comment made me concerned
Tony.
Also I still don't know for certain what I have to do to make it balanced!! apart from buy BIG heatsinks
You build two stereo BA-3 amps, rewire one resistor on each one, and you've got a pair of BA-3B mono amps.
hmmm ok still in dummy mode I just realised that there are two ways to make a stereo amp dual mono, and shared power supply.
I'm still not certain whether I will need to make two or four PS's in total if I go for a balanced BA3 (I would build them as mono-blocks).
Is it necessary (or if not then desirable) to have separate transformer and power supply for each half of the balanced amp?
I can do four PS's but if it is just overkill I would probably rather save the money
Tony.
I just realised that there are two ways to make a stereo amp dual mono, and shared power supply. I'm still not certain whether I will need to make two or four PS's in total if I go for a balanced BA3 (I would build them as mono-blocks).
Is it necessary (or if not then desirable) to have separate transformer and power supply for each half of the balanced amp?
I can do four PS's but if it is just overkill I would probably rather save the money
Tony.
