Actually from this and past experience I think having a CCS entirely or predominantly as an i/p stage load does tend to smooth out the sound somewhat. I think this may be caused by current lag at higher audio frequencies, but having even a small portion of the current coming through a resistor helps quite a bit to reduce this effect.
I'm going to wait till I have my new PSU before I make up my mind about this.
Why, if it is fast enough ? Don't you think it is the contrary, and non infinite resistance tend to increase transients ?
Looking at square waves (no overshoot, no rounded corners) at low and high level is enough to make our mind, i presume.
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Well, when I was developing my fetzilla I tried i/p stage load as CCS for a while - with many cheap resistors in the circuit but very good FB resistors this brought big benefits because of the very big increase in Open Loop Gain, but later when I have good resistors in every position the amp sounded much better with a simple resistor in this position - much more immediate & lively sound - by comparison the CCS sounded refined & polite but lacking in vitality.
Later when I researched this in spice I found that the only difference I could see was an earlier phase shift of the current with respect to frequency when using the CCS. Adding a parallel resistor helped to reduce this shift but not 100%.
Later when I researched this in spice I found that the only difference I could see was an earlier phase shift of the current with respect to frequency when using the CCS. Adding a parallel resistor helped to reduce this shift but not 100%.
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TSSA 1.6 vs DC linked Fetzilla:
Have to wait a bit for this comparison - the incredibly refined sound of TSSA1.6 made me realise that I had some "housekeeping" to do in my design so I'll report the differences & similarities once I've finsihed - should be in a day or two.
For now all I'll say is that they are both sounding very nice indeed 😀
Thanks Sonny - I'm still learning . . .
Have to wait a bit for this comparison - the incredibly refined sound of TSSA1.6 made me realise that I had some "housekeeping" to do in my design so I'll report the differences & similarities once I've finsihed - should be in a day or two.
For now all I'll say is that they are both sounding very nice indeed 😀
Thanks Sonny - I'm still learning . . .
With some mods now done to my amp I began to do a comparison today but in the end I abandoned it quite soon because I believe to a large extent I would just have been describing the differences between the different PSU arrangements each amp has - it would not have been easy for me to give each topology identical supplies at this stage and for me it is the topologies that I am interested to compare rather than the PSU's.
At present my amp has 2 x 22,000uF shared between two channels + 470uF on the board
TSSA currently has 22,000uF for each channel + 3670uF on the boards.
I believe that both amps will improve will the new supplies I am planning. TSSA should sound smoother & my amp should gain better defined midrange.
Please don't misunderstand me, already both amps sound very nice but I believe the differences I can hear are to a large extent defined by the different PSUs.
I will be travelling for a few weeks this winter so it may be a while before my real comparison gets made.
At present my amp has 2 x 22,000uF shared between two channels + 470uF on the board
TSSA currently has 22,000uF for each channel + 3670uF on the boards.
I believe that both amps will improve will the new supplies I am planning. TSSA should sound smoother & my amp should gain better defined midrange.
Please don't misunderstand me, already both amps sound very nice but I believe the differences I can hear are to a large extent defined by the different PSUs.
I will be travelling for a few weeks this winter so it may be a while before my real comparison gets made.
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That make sens.
So CCS have to be done with the fastest devices we can find. May-be FET cascoded current source ?
It look like it is a crucial point. Lack of linearity VS lack of response's speed.
An external PSU very high voltage with high Z resistance could help to find the audible limit ?
But i agree with you, PSU is the first to look at.
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One more TSSA is almost ready.
1A with 26V rails, dual mono.
All the parts came from what I had in my parts bin and the chassis was salvaged from an old class A amp.
For the moment it is on the test bench and doing well. Very stable, easy to adjust seems to work fine.
looks good on the scope too.
Will do some more tests tomorrow and hopefully listen to it.
One question only. Is there a way to make a balanced input for TSSA? It would be handy!
1A with 26V rails, dual mono.
All the parts came from what I had in my parts bin and the chassis was salvaged from an old class A amp.
For the moment it is on the test bench and doing well. Very stable, easy to adjust seems to work fine.
looks good on the scope too.
Will do some more tests tomorrow and hopefully listen to it.
One question only. Is there a way to make a balanced input for TSSA? It would be handy!
Attachments
Looks like the chassis of a french beast from the 80'es!???
I could design a small frondend for it that would accept balanced input very little or no feedback.
Would that be of interrest.
I could design a small frondend for it that would accept balanced input very little or no feedback.
Would that be of interrest.
You are right, Audioanalyse A9.
Regarding balanced input, that means another active stage. I don' t know, I may try it.
Regarding balanced input, that means another active stage. I don' t know, I may try it.
I could make something very transparent with folded cascode and no output buffer.
So this would be like a true 1stage design.
So this would be like a true 1stage design.
Let' s try it then.
There is quite a distance from pre to power amp, so I prefer balanced whenever possible.
There is quite a distance from pre to power amp, so I prefer balanced whenever possible.
You can just add a - differential input for a balanced stage. Look at the SSA Thread.
No stage added.
http://www.diyaudio.com/forums/solid-state/193923-simple-symetrical-amplifier-42.html#post2713472
http://www.diyaudio.com/forums/solid-state/193923-simple-symetrical-amplifier-132.html#post2731793
It will improve PSRR rejection too.
That's how my SSA is working, so far.
No stage added.
http://www.diyaudio.com/forums/solid-state/193923-simple-symetrical-amplifier-42.html#post2713472
http://www.diyaudio.com/forums/solid-state/193923-simple-symetrical-amplifier-132.html#post2731793
It will improve PSRR rejection too.
That's how my SSA is working, so far.
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Hey, it does not add a lot to the design.
Pros:
No extra stage.
Cons:
This does double number active devices.
It Will be difficult to get High cmrr values.
It should be the main reason to go diff, that we wants to obtain High cmrr values.
I do not believe This solution to be optimal.
Pros:
No extra stage.
Cons:
This does double number active devices.
It Will be difficult to get High cmrr values.
It should be the main reason to go diff, that we wants to obtain High cmrr values.
I do not believe This solution to be optimal.
Just need to fine tune the resistances value of the -stage. But it is a necessary practice for all symmetrical asymmetrical recievers.
Even the Analog device SSM circuit is laser trimmed in the wafer.
Two, it can reduce some distortion, and reduce noise from the psu.
Hello Esperado.
You also have to remember that this is not practical to do for them who has purchased and build the TSSA V1.6.
Thanks Sonny, I will try it soon.
Now I am listening to it and what can I say? It is a fantastic amp. Musicality with resolution and not harsh at all. Highly recommended to everyone with suitable speakers for it. I don' t think people know what they are missing!
It is powering my main system from 80Hz and up. Horns about 100dB and more than 15R load.
Had before various incarnations of F5, Aleph J, EL84 Baby Huey, this one beats them all.
Thank you very much Sonny.
Now I am listening to it and what can I say? It is a fantastic amp. Musicality with resolution and not harsh at all. Highly recommended to everyone with suitable speakers for it. I don' t think people know what they are missing!
It is powering my main system from 80Hz and up. Horns about 100dB and more than 15R load.
Had before various incarnations of F5, Aleph J, EL84 Baby Huey, this one beats them all.
Thank you very much Sonny.
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