Simple Symetrical Amplifier

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Hello Jay,

I pasted this site link to illustrate my request about the SLC

I would like to make a very fast and linear amplifier with lateral mosfet output 2SK1058.

The speaker : http://www.hometheaterhifi.com/imag...s/magneplanar-1.7-speaker-impedance-phase.gif

There is no proof yet that SUPER fast amplifier is better (than "sufficiently" fast one). The SLC is fast but less fast than Esperado's SSA Crescendo. To increase the speed is difficult because faster means more prone to oscillation. I think the high voltage of the SSA crescendo also contribute to the speed (SLC uses very low voltage rail, may be 1/3 of the SSA Crescendo).

The SSA crescendo is probably the fastest amp here, but I don't think it is capable of driving some electrostatics. But to my surprise, your planar speaker is not really that difficult? I'm not sure if it is 100% planar or not. EDIT: Eww! I was looking at the purple chart. The impedance chart is the orange one, which is a difficult load. Esperado will explain if the SSA crescendo will be suitable, but I think it is not.

What do you think of a Moskido? Too slow? EDIT: I think the nature of a planar strings is slow, so Moskido might suit the speaker better.
 
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but I don't think it is capable of driving some electrostatics Esperado will explain if the SSA crescendo will be suitable, but I think it is not.
I don't think too, would need more than 4 paralleled power fets at least (i think 6) for each branch, so driver modification to increase the power, and no idea about the stability.
If i remember well, here, in this thread, L.C had proposed a special SSA for very low impedance devices :http://www.diyaudio.com/forums/solid-state/193923-simple-symetrical-amplifier-93.html#post2731793 and http://www.diyaudio.com/forums/solid-state/193923-simple-symetrical-amplifier-93.html#post2731793
I think (i have no experience with electrostatic drivers) bipolar power transistors will manage better the capacitive loads.
Thoughts ?
 
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Thinking about electrostatic loudspeakers and fast amp, my first thoughts where those ones:
The transients and flat phase curve advantages of a very fast amp has no sense, here, because the amp will deliver his hf components in a near short circuit. PSU will not be able to deliver this fast changing current and the fastest amp will be... slow.

If we consider that the current feedback quality is on the TIM side, and this, because the CR is fast enough to make his correction in time (no pole limitation), we can go for CR. But the balance between voltage and current will be nonsense at hf and we can worry again about TIM here where global speed (and slew rate) will only present inconveniences..

So, no need to look for the fastest amp ever. On the contrary, i think the main objective would be to go for current capability and stability, and try to reduce as much as possible the bandwidth, on the hf side, before the input, to avoid any fast signal to introduce TIM by lack of current during transients. A lowpass filter need to be tuned with care before the input.
To summarize, looking for a superfast amp to power an electrostatic loudspeaker is like finding a Ferrari to plow a field, might not be the best tool.

For all the other aspects, damping factor influence, advantages between FETs and BJTs in the output, i will try to explore what's happens in the cr loop using simulation to make my mind, the subject is interesting.
 
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Hi every body!
Is my schema correct?
 

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PSU will not be able to deliver this fast changing current and the fastest amp will be... slow..
I have made a quick simulation of the Crescendo with 5µf paralleled with the charge. Stability looks ok (but sim is not real world).

As expected, the bandwidth is reduced from 7mhz to 2Mhz (-3db). Slew rate is not fantastic anymore and square waves shows an overshoot: I'm sure the current monster SSA will perform better in a more healthy way..
 
No need for a Director of Marketing.;-)

nor advertising agency.

hehehe Esperado I'm glad you're in funny mood, so many new info from you lately, really appreciated your support. :cheers:

Regarding your quote, I meant that presented sch will work if nalimko33 will follow some rules, not that it will work just because it is SSA. My bad english use I suppose. Sometimes I hardly explain what I would like to, but eventually after few posts I usually manage to be understood. :bawling:

As "go for it" matters, I meant that nalimko33 has talent because he presented his own version of SSA sch, so I meant, yes, go for it, experiment, measure, enjoy DIY work and end result, not just follow some cook book recipe. :wiz:

Uff that was I meant, not marketing really :innocent:
 
...... thank you dobrivoje corrected :headbash:

Regards Alex.
 

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Alex,
I would like to note a weekness in ground scheme in your PCB drawing.
The input ground should be seperated from the zobel and both should go independently to the main power supply capacitors null point.
otherwize there is a good chance of positive feedback and oscilation from voltage drop on ground line that goes from PCB to main capacitor bank.
 

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It was clear, but I could not resist to tease you.

Teaser aaaa :cheers:

May i propose: 'It will rock, since it is SSA, roll for it." :)

That's a nice one, in short, all what's the SSA about. :up:

Is your splendid amp even better after some breaking time ? Still happy with the way it sound ?

As you probably missed it, I sold the SSA to a friend recording engineer, who has control over the whole recording chain, from microphones, recordings, mixing and mastering (two master systems listening/tuning for final master). I was there two weeks ago, because he overloaded 4 A/T mains fuse which blew when he performed some low frequency room measurements, now 5 A/T is in action. Than I had opportunity to listen to some material and the amp definetely become very refined, musical, not loosing its transient response, speed and transparency. It is a good part of the whole mastering system, doing what is suppose to do, not being recognizable in the chain. Very good sound of that system I must say. :yes:
 
... he overloaded 4 A/T mains fuse which blew when he performed some low frequency room measurements
A recording studio is, indeed, the best place to evaluate the reliability of an audio component on the long time.
Did this amp was a symmetrical input version ? Did the symmetrical version brings power supply ripple rejection to the same level than a classical voltage feedback amp ?

Your fuse's story makes-me remember something:
Cabasse ( a well known French loudspeaker manufacture) wanted to demonstrate to me their top line enclosure was able to be used as a studio monitor. I had warned them about the particular constraints of studio work, but they insisted and came to the studio with a pair of baffles. The two enclosures were plugged-in, and the level was tuned to 110db spl, same than my JBL. Then we listened the last mix at normal high level. Everything were fine, until i pushed the "Solo" button of the kick drum track. Instantly, the two dust caps fell on the mixing desk, like dead leaves.

Well, i hope you had ordered all the parts of your master piece in several copies and that you will build - and keep for ever- an other sample of your prototype that nobody here allowed-you to sell !
 
...... I sold the SSA to a friend recording engineer, ........

With so many permutation and combinations it is hard to say where one is !
What circuitry did this amp use ? Is it on one of the pages of this thread ?
I think you guys who keep progressing from mod to mod have some idea of where you are but those following the thread and intending to try one of the creations could get lost.
If you have compared a particular scheme in the studio, which one was it.
You started a great thread . It really got CFB fans worked up ! My preferred amps are all CFB here.
Cheers.:)
 
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