Thankyou very much Sir Wahab, i see your post about SSA Allbjt with driver, in post #196, so with my schematic above i got around 1% at 1khz? and only 5W on 8ohms?
Not all distortion is created equal, so I can testify that the simple amp can sound very good at modest power levels. A bigger problem for the simple BJT version, will be getting to a stable operating point. You will need a good current source to replace the resistors R3,R5 for the front end, and you will need to incorporate LC's NTC thermal compensation scheme.
Sheldon
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Of course the max power is higher , in the vicinity of 50W and the 1%
distorsion is for 5W , at higher power it will rise to a few % at 16W
and so on while distorsions such as intermodulation will also skyrocket.
As said ,better to add drivers to the power devices (or use darlingtons
wich are a driver and a power transistor packed in a single case),
that s necessary to have a good enough amplifier.
There must be a variation in this extensive thread that was checked
through a build that should suit your needs.
Equal or not , without drivers it is high and i think that no one will contest this point whatever the burned to the rope "good sounding" argument...
Hi Lazy Cat, Sorry for looking at this circuit so late in the day. Great job 😉 ! Its not over yet, according to some models, you will have many more spawns 🙂
Hi naf.
Good to see that you want to go further with SSA than just stop and type and discuss and etc. 😉
Your schematic seems okay, but some points...
1. Use fixed resistors of 1K2 value in place of R3 and U2.
2. Use offset control at the input like your last SSA. Two 10K trimmers + 1uF + 1Meg. Much easier.
3. Use 10K for R17. 1K for R7. Remove R18.
4. R4 and R8 should be 1Watt type.
5. C3 in not essential. So you can omit it.
p.s. Please ignore whatever whoever says about the merits/demerits of your schematic, it's purely their own prejudice. YOU are building YOUR own amplifier, YOU decide if it sounds good or not.
All the best.
Attachments
YOU decide if it sounds good or not.
.
As last ressort negating the nature s laws....😀
It will have distorsion higher than 1$ chip amplifiers , whatever you decide
and the guy has the right to know it before listening to your sectarians opinions.
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Please, could-you comment your own SSA build and share your experience about-it ?
That s not the point , the guy asked for some infos about his schematic
and he got some from different members.
As for the experience i will rely on yours instead....
Seriously , would you build for yourself what is seemingly the worst iteration
of this amp.?..
And why didnt you build this version to check if it wasnt better sounding
that what you have at hands ?.
I guess that we both know the reason , but whatever it s somewhat
strange to see people proposing to others some food that they wouldnt
even considerate for themselves.
The guy said that he s not experimented in this field , so why should
he learn the things the hard way when there s is seemingly a lot
of people that could provide him good solutions to get an acceptable
amplifier in respect of today s standards.
That wouldnt take him more efforts than be thrown wasting money and time building a version whose caracteristics are unworthy of a midi mid-fi compact stereo amp.
Quite the contrary.
Thank you wahab. The guy knows me well. I am sorry that this is very painful for you.
You probably missed his previous posts where it is clear that he is the experimenting type, not babble type, unlike some people in this forum. Also I doubt he cares about scientific facts more than the sound quality(subjective, we can't enter). What's your problem if he's tin-eared and likeS the distorted output???
He has mentioned he is a beginner so wouldn't it be better to show him a picture of the proper darlington config for his schematic or just briefly describe it indicating the parts needed? This is called helping. "lightyears away from a 60's hifi" is not helping.
I won't argue with you anymore on any topic. Have been flamed enough, crackling all day.
Happy listening.
PeeCeeBee with servo. As promised. A solder mask has been added. Hope I didn't miss anything.
🙂
🙂
In fact, may-be.
That's exactly the way i proceed when i want to learn something from a topology.
Having a distorted open loop is a good way to evaluate feedback behavior.
Optimizing simple schematics is a good way to evaluate (and enjoy) the influence of each step.
Then it is easy to add good CSS and look/listen at the changes, current margins as you advice, improve some poles speed without/with Cascodes etc...
It seems obvious (may-be i'm wrong ?) that it is the way Naf want to proceed, because there is in this thread enough ready to use versions of SSA.
Of course, everybody have no interest to experiment again and again the same things, so there is some reptilian habits after some years ...it saves time but can let-us away from some new interesting track......
As a example, Shaan has experienced CCS vs single resistance and shared with us very interesting listening impressions about that.
My mistake to had not taken enough attention until now about CSS behaviors in the time domain. A new track to experiment, thanks to him.
Hi naf.
Good to see that you want to go further with SSA than just stop and type and discuss and etc. 😉
Your schematic seems okay, but some points...
1. Use fixed resistors of 1K2 value in place of R3 and U2.
2. Use offset control at the input like your last SSA. Two 10K trimmers + 1uF + 1Meg. Much easier.
3. Use 10K for R17. 1K for R7. Remove R18.
4. R4 and R8 should be 1Watt type.
5. C3 in not essential. So you can omit it.
p.s. Please ignore whatever whoever says about the merits/demerits of your schematic, it's purely their own prejudice. YOU are building YOUR own amplifier, YOU decide if it sounds good or not.
All the best.
Thank you very much dear Shaan, i'll try to correct my ssa bjt as you suggest.
Thankyou guys for all your suggestion and critics on my journey to experiment with my ssa bjt.
Yes, and I think we can trust Shaan listening skill...
Actually I have mentioned before Shaan's post about this, that I have preferred to omit the ccs (but with regulated supply) because it seems it takes something from the music.
On the other hand, THEORETICALLY, the resistor current source is not "stable" against the feedback current and this affect operating points in every places. MiiB for example, has "decided" that a current source is a must. There is also a mention that the ccs must be very fast, hence JFET and so on...
Thinking to that, did-you had taken care for no overshoot on 20Khz square waves at various levels while you where experimenting CSS ?
Did-you set a low pass filter before input of the amp at this time?
Can-it be the little added distortion by less constant current have some nice effect on the amp signature ?
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