My post was a joke, because some people has big sentiments against those who claim can hear things. Those who can hear things, naturally don't have sentiment against the other party.
It's like people telling they can see ghosts. Most of the time they are just liars. But it doesn't mean that ghosts do not exist. We have to believe that there are things that we cannot understand. Only non-intelligent people who usually think that they understand everything, that if they cannot see a thing then the thing must not exist.
Dear Salas,
this is the last picture i take when my SSA playing music... sorry for shake picture.
Attachments
Thank you sir, the brown one is KZE.Is it because the bass shakes the camera?
Nice. Good choice on Nippon Chemicon caps when in hot environment near the sinks. Very reliable brand. Are the brown ones KMG or KZE?
When you will pack it up in its final box measure the temperature on the electrolytics. Rule of thumb is you double half a quoted cap's spec sheet lifespan for each 10 degrees decrement from printed max temp on the cap's sleeve. The 85C black SMGs will go first in other words, but if the temperature is moderate they are going to live long enough. Example: If you got a 2000 hours 85C electrochemical capacitor working in a 55C environment, then 85C-55C=30C i.e. 3 times 10 degrees less than its max. Half 2000 hours is 1000 hours. 1000*2*2*2=8000 hours. That is how long it will live if the manufacturer is accurate and reliable.
It was an opportunity to refer because I don't see that consideration much around when people ask "what cap is good for my amp?". ESR, value, subjective tone, are usually mentioned but not relative lifespan. Well, maybe a Nichicon Muse KZ is sounding nice but I would not populate a Class A Pass with those because 1000h 85C. But I would on a preamp etc. Same thinking for other high temp builds, like in valve amps.
That rule of thumb estimation is for staying within 20% value and 200% DF degeneration by the way. There are many old amps that run on dried lytics without bulging effects. Still they rejuvenate markedly after a re-cap.
That should keep the fins under 50C probably. Key is the temp on the caps when boxed and installed Always good to know, the relative lifespan reference came in the flow of discussing Nippon and types but its generaly useful. Not that Naf's test build is a worrisome example.
BIGBT output stage. They are good. Just good. No more than goodI'm skeptical you know, about this kind of output stage. They all have strong character.
Everybody's just talking about BIGBT, simulating, etc, but did anybody actually made an output stage with them? Why are you all so sceptical about BIGBT? I am using them in all power amps built in last 10 years and people who's heard these amps had only positive expressions. The only task to make BIGBT is to match output BJT's, but that would one do also by any power amp. So what's the hack, really do not understand. Besides I stated many times what are the advantages of these three transistors - compounds together. Pure positivity.
Cascodes I use at input and VAS, lately Hawksfords driven ones, they do no harm and also enables the use of very good small signal high gain transistors with just a little heat dissipation on them. Sounds better to my opinion.
Yeah, I quit building class a sometimes ago. In a hot country like ours its more about room temp than electric bill.
If naf's land is cooler or has an AC then it'll be good for the health of the electros. I have used nippon 105c caps only once and in a 100w hot amp. I hope the customer won't call me anytime soon.
If naf's land is cooler or has an AC then it'll be good for the health of the electros. I have used nippon 105c caps only once and in a 100w hot amp. I hope the customer won't call me anytime soon.
Everybody's just talking about BIGBT, simulating, etc, but did anybody actually made an output stage with them? Why are you all so sceptical about BIGBT? I am using them in all power amps built in last 10 years and people who's heard these amps had only positive expressions. The only task to make BIGBT is to match output BJT's, but that would one do also by any power amp. So what's the hack, really do not understand. Besides I stated many times what are the advantages of these three transistors - compounds together. Pure positivity.
Cascodes I use at input and VAS, lately Hawksfords driven ones, they do no harm and also enables the use of very good small signal high gain transistors with just a little heat dissipation on them. Sounds better to my opinion.
I am on the way to live with BIGBT.....not sceptical at all...The only thing with BIGBT is matching as you said, and it's more triky than with conventionnal output stage since we must match NPN with PNP and not just NPN with NPN and PNP with PNP. For example in my case with 100u MJL3281 and 100u MJL1302 i only obtain close matched 4 pair MJL3281/1302.
May Be matching is easier with NJW3281/1302 as ONsemi claim in his datasheet that "NPN/PNP Gain Matching within 10% from 50 mA to 5 A"
Marc
Because the latching's problems with the first serial of IGBTs ?
In fact, i feel very difficult to get an opinion on how sound a device, as it we are obliged to compare them in different implantation. I feel like i prefer Fets against Bipolar for output devices, but i'm not so sure it is more than the way they look on a schematic
In fact, i believe the main question, about a power device in an amp is the way they dissipate instant heat of their junctions.(Dynamic distortion). Is the Case more important than the technology ?
Again, i think that some people have bad opinion about Cascodes because they were sometimes used to get around of power dissipation of poor silicon parts. (Same problem of instant dissipation), and, so driven near their dynamic power limit ?Cascodes I use at input and VAS, lately Hawksfords driven ones, they do no harm and also enables the use of very good small signal high gain transistors with just a little heat dissipation on them. Sounds better to my opinion.
Or, because they are fast, they can overdrive poor following stage with more HF than it can deal with, generating TIM ? It is important that all poles in a closed loop system are tuned in a way that each one is at least as fast than its previous one. Increasing a stage's speed can have negative effects on the next one. But it is not this better stage witch is to blame
Everybody's just talking about BIGBT, simulating, etc, but did anybody actually made an output stage with them? Why are you all so sceptical about BIGBT? I am using them in all power amps built in last 10 years and people who's heard these amps had only positive expressions. The only task to make BIGBT is to match output BJT's, but that would one do also by any power amp. So what's the hack, really do not understand. Besides I stated many times what are the advantages of these three transistors - compounds together. Pure positivity.
Cascodes I use at input and VAS, lately Hawksfords driven ones, they do no harm and also enables the use of very good small signal high gain transistors with just a little heat dissipation on them. Sounds better to my opinion.
Hi LC.
We all know that Jay is one who can hear "strong character" in BIGBT. Well if he does hear then he must have built it and listened to it, and he was not satisfied with the sound. The thing that keeps confusing me is whether he matched the NPN to NPN, or NPN to PNP; the later, as Idefixes mentions is necessary for "true" BIGBT operation. Most probably Jay didn't go that way.
My second idea is that Jay prefers high amount of even order distortions as he often mentions in his posts. Funny thing is that SSA, being a Sym amp, has least or nothing to offer Jay in this even order persuit, unless he removes the cascodes, doing which will disbalance the current through the input BJTs to a much higher degree, and Will result into more even order distortions as the inherent symmetry between the upper and lower currents is lost. And if he likes it then its HIS preference. Not the "general" preference.
Also, after finishing my SSA I have been having strong doubts about the accuracy of the simulator. I have built many amplifiers depending on the simulated distortion spectra, and the resulting sound have always matched that graph, for example the DOZ simulation shows clear emphasis on the 2ND harmonic only, and if you read Rod's article then you'll see he clearly mentioned this phenomena. I built it and clearly the sound was "WARM" and "FAT" and "SWEET". OTOH, SSA graph looks like it should have a "bright" character as signified by the predominance of odd harmonics, BUT, the sound is between "sweet" and "neutral", nowhere near "bright" or "clinical", even with clear and sizzling treble.
If Jay built the SSA BIGBT with cascode then I can assume he hated its sound as the sweet character that he craves for, is gone.
I can live without it(even orders) as I hear nothing but puuuuure and lively music through my speakers, even at very high volume, which DOZ fails to do.
All in all, SSA with cascodes and/or matched BIGBT pairs is true SSA, otherwise NO SSA.
Thanks for the info on the NJL devices. It looks like I won't have to buy too many for 4 matched ones.
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Yes. Strong means impressive, especially at first sight. About sound, I prefer to "feel" the music, not to "listen" to it. My prediction is that I need 2 things:
(1) Musicality --> sonic/dynamic --> current or voltage swing.
(2) No dissonance/fatigue --> no TIM/IMD?
No I didn't match my BJTs. There are 2 things about the output stage:
(1) Matching issue (2) I'm familiar with mosfet-BJT (only one BJT) arrangement, and couldn't see anything special. The first issue is worst.
I don't know if my posts tell that I like even order harmonic. Actually I don't. Second order is impressive at first sight. At long run it is just like any other distortion: fatiguing. I think you are the one who like second order distortion when you "walked on the moon" with your DOZ_JLH (its an amp with the most dominant 2nd order that I have seen)
That's not what I found. I find that without cascade, often the THD is lower (if 2nd order is high, total THD usually high also). And the stability is better without cascode, especially when working with CFP output.
I didn't find the predominance of odd harmonics with SSA. It is symmetrical, but the distortion character is like SE. Not clinical at all.
All in all, SSA with cascodes and/or matched BIGBT pairs is true SSA, otherwise NO SSA.
Many good examples of successful CFB amps are without the cascode, coincidentally.
Yes Jay, and everybody you see in this thread has the same requirements as you, and often more. And those who build the BIGBT like it. You don't, no problem, all's cool.
So you are discrediting the BIGBT for the matching issue, I see it now. IMO, one should not dismiss something as bad if they can't afford it. As a matter of fact, I can't afford the BIGBT with my current income, and in future maybe I will. And when I try the BIGBT and fail to like its sound only then will I be acceptable to make comments on it, provided I do it the way it should be done, i.e. matching the BJTs. Looking at this config through the glasses of my previous familiarity with any particular config will be plain prejudice from my part. No offense.
You are totally right Jay, in saying that I like second order. I do. Because if I want tube sound then I Must use a tube. If I want sweet sound I must add the 2nd harmonic. There is some special attributes about DOZ when played in low volume, that you can't achieve with a symmetrical amp, like SSA. And this, in no way is a discredit to SSA, because SSA can make the sound ALIVE and the feeling of being in a LARGE auditorium starts brewing inside your head, something DOZ just can't do, the sweet second harmonic becomes so high that it starts to mask the fundamentals aggressively. I don't see any reason to hate any of these two amps for any reason, I said I can live without the even orders, not that I hate them, clear?
I see, CFP. Now it's clear as daylight. I found cascodes effectively reducing distortion, increase bandwidth by at least a MHz and overall way better current balance between upper and lower half resulting into much lower even orders. As you know I am using LATFETs at output, without zobels. Obviously our two configs are parsecs away from each other, so I won't dare to compare it to your's.
You might find the odds to be predominant once you install those cascodes. I didn't. Does it mean my cascodes are not working, absolutely no. Does it mean you should trust my findings, Absolutely No.
And, not co-incidentally, none of them is an SSA, as I said, plain truth.
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