Bimo sorry, i can't understand what you say😕
Do you mean a scope test at 100Hz?
Do you mean a frequency analyzer picture?
Had a 20 year old sony with a bootstrapped VAS = 100mv.
Replaced all the caps ... <10mV again. NP electro does degrade after decades.
Had both my HK680 and an old 25 year old sansui , both servo'ed.
Main PS and smaller decoupling caps were replaced , but amps still worked
and were <5mv offset.
No free lunch. To get 20+ year absolute offset , at least ....
a servo is needed. Semi's would age "as one" , so currents would balance through the decades.
These factors can only be learned by repairing 20 year old
classic audio (from the dumpster). There , I admitted it. 😀
EDit- on the slews , the cap multiplier would extend any life of the IPS
PS caps by a huge factor. The DC blocker cap (or a bootstrap) has to
deal with the audio signal for them 20 years.
After 30 years , I would say the spooky,K-ND/C , or symasui would be
nearest original spec. None of the other would fail , but might need
caps to regain spec.
PS - after 20 years- the 6 OPS caps would need replacement , regardless.
OS
Thanks OS for the answers, it was what I thought you would say about stability over decades. There is just no way to stop the aging of electrolytics over that time frame, just the nature of the beast.
You are correct.I tested at 1khz, I just tested at 20K and I see the little latch like in your picture. However, the square waves look awesome! As far as the low end, the square waves do look very flat compared to some of the other amps. I will have to look at the ND down low like that and see how they compare.
I installed 47R emitters for the VAS and the emitters on the LTP are now at 4.25mA. The LTP transistors are barely warm so I'm not sure if there is a problem.
As for offset, when I have both sides of the VAS set to 11mA I have .5mV offset. I purposefully adjusted the VAS to 11mA on one side and 9mA on the other and still only had 13mV offset. This IPS definitely does not need a servo.
Ferrari? Better top end speed, handles great, rides terrible and costs 5X what a Mustang does.
Now I have to hook up the ND and Symetri side by side and see if there if 5X the performance. I doubt it. 😎
I installed 47R emitters for the VAS and the emitters on the LTP are now at 4.25mA. The LTP transistors are barely warm so I'm not sure if there is a problem.
What resistance value you mound in position R4,R5 R21, R22?
Somebody put up this link on another thread and I thought someone may be interested in it. NASA specifications for soldering and crimping connections and such.
http://snebulos.mit.edu/projects/reference/NASA-Generic/NASA-STD-8739-4.pdf
http://snebulos.mit.edu/projects/reference/NASA-Generic/NASA-STD-8739-4.pdf
Maybe Mustang and Dodge Charger would be a better analogy. 😀
Both IPS's are real good. (it seems).
OS
Both IPS's are real good. (it seems).
OS
Those are still 1k. I'm going to try 1k2 there and see how that looks.
Blessings, Terry
So it's good at <1Khz , and not really bad at 20K.
If you clipped in the real world , your fundamental wave would be LF
(bass , most likely). The HF would be "riding" that LF waveform.
When it clipped , the minimal content >15Khz would be overwhelmed
by the overload harmonics.
So , most likely not a real world issue.
OS
You can barely see a tiny distortion of the trailing wave form and only above 15khz. I see folks saying they can hear that high. I wonder when the last time they actually tried. I have good headphones and I can't hear it, not even if I try to sneak up on it. You coiuld roll off everything above 15khz and no one would be the wiser. Because I have built so many amps I get asked all the time what amp to build. This is the one I will be recommending. Easy to build, very tame, measures and sounds great. My new favorite.
Of course, we're still waiting on the MiiB IPS, 😉
Of course, we're still waiting on the MiiB IPS, 😉
Is this still a battle..?? The VFA Leach sounds bold Brutus, the CFA (VSSA) sweet and soft, but weak and unfocused in the base, CFA diamond much better, more solid ,but still a little thin compared to the leach. My last IPS is way better on all parameters. Detailed sweet with that magic warm slam. The way it conways emotion in the recording is just amazing.
Any PS cap in the IPS would be subjected to much less ripple.
By the time the rails go through the driver R/C , multiplier -
the IPS does not "see" much ripple.
Capacitor Life Calculators | Electrolytic | Film | Ceramic | Illinois Capacitor
That link shows cap heating by ripple as shortening lifetime. All
the other "capacitor lifetime ripple" (Google search docs/pdf's) support this.
The multiplier capacitor's ripple is also attenuated by the multipliers
divider and the OPS's driver decoupling (but less).
The main OPS decoupling would be where you might want the VERY
best 100C over- rated electro , it is subjected to the most thermal
stress (through heating).
OS
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