We are not dang BATS ! But anyway , what the heck , this thing has a bandwidth of over 120KHZ.
At 50K ... ohhhh .01%thd (below)
At 100k - .1%drop cdom 56p to 47p , .06% .. same as DX amp at 1k.
OS
You right were not bats, it was just to show whats it capable of. Please dont call DX here, he doesnt believe in THD numbers or any other for that matter, I believe in the numbers as well as the sound of the circuit, and when the numbers are better the sound is just a little bit better too.
Ill rather leave the 50khz plots too, you are not going to like but any ideas how I can resize the captions from ltspice so that I can attach them here because of size restrictions.
Another member recommends plotting the lissajou between input and output (differential between input and output, output attenuated for cancelation of the fundamental) at 100khz.
Ostripper, I don't know how controversial this paper is, but here ya go.
high freq inpact on brain.pdf (application/pdf Object)
- keantoken
Ostripper, I don't know how controversial this paper is, but here ya go.
high freq inpact on brain.pdf (application/pdf Object)
- keantoken
I dont find that controversial at all, as a teenager I got headaches from people playing around with dog whistles.
Anyway here are the plots, hope they come out.
Attachments
Do, you think you can tell us the amount of NFB? In both db and the actual number please... Also, I would like to see the spectrum taken before the output inductor, since this attenuates the HF components.
Ostripper, why don't you give your amp a triple like Homemodder's and simulate again?
- keantoken
Ostripper, why don't you give your amp a triple like Homemodder's and simulate again?
- keantoken
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only a 1-2 uA from the input signal will drive the 1.1ma LTP currents with the
Hfe 600 Zetex. with a 2n5550 , 10-15 uA is required to do the same job.
At 2uA/1.2mA ..that is a gain of 600 , which , by the way is what the zetex model specifies. If I used a pair of FET's or mosfets at the differential , the gates will show just nA (nanoamps) "draw" , and just the voltage at the gate will determine drain current.
Three reasons ,
1. - Using only 2 or 3 pairs in the OPS does not load the driver excessively. less that 500uA at 2R full power. The VAS in this one runs "hotter" (4-5mA). At 5 pairs and up a triple would be required. Scaling this down to a 60-100w amp at 50V and 1 pair the 2 stage EF3 is more than adequate.
2. - T comp. - the complimentary Vbias is easily the best, short of E stuarts circuit or the lt 1166 active bias circuits. A 2 stage EF is the most forgiving / easy to compensate thermally.
3. This type 3 EF performs about the same whether in double or triple form.
I actually got under .001 at 20k (.0008%) , but who gives a hoot ??
OS
Thats oscilating for sure.
Ill tell you what Ill leave out the coil completly, thats how this amp gets used in car setup using 4 ohm subwoofers sometimes. It doesnt require any coil for stability, I put it on the sims so I dont have to hear wheres the coil from 10 30 members. How about 80v p-p, just 4v shy off clipping, so keep it mind. THD20 is now 0.0032.
Keantoken if you sim circuits with triples youll quickly understand how dificult it is to do, in most cases it always shows oscilation, just ask ostripper, he knows. The easiest way to avoid this is very high speed frontends. If you sim most commercial circuits using triples they will show that they oscilating but in real life they work just perfectly.
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Actually I have to revoke my earlier comment about that FFT. It looked bad to me since the higher order stuff was near the level of the low harmonics. Actually I see that the higher order stuff is on the same level as your amp, but the low order harmonics are very low. That's the funny thing about OLG, no matter how much of it you have, you seem to get the same level of ultrasonic harmonics.
I'm not sure, it may have appeared that I was making a malevolent comment but that is not the case.
The really low noise floor is confusing me a lot!
- keantoken
I'm not sure, it may have appeared that I was making a malevolent comment but that is not the case.
The really low noise floor is confusing me a lot!
- keantoken
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At full power the odd harmonics do take over, but thats not surprising in AB amps, but look at what low THD levels. At lower levels the amp displays perfect hiraga type distortion pattern, if thats what you into. If I add another 2 active parts which would bring it line with os circuit it will display even less THD, 2 more devices than that and youll drop off your chair looking at the THD figure espesially if its at low power or low frequency like 1k.
KEAN what is going to surprise you the most is that open loop gain is only 65db. Unity gain is at around 6 MHZ. I dont want to show plots yet as Im not sure this easy way that spice uses to view gain and phase margins is valid in my circuit, but those are the figures obtained for now.
This should tell you what type of circuit it is, and soon Ill have another one that I can probably show here. Another member has shown such a circuit 5 6 years ago on this forum except I dont think he realised the performance that could be obtained from it, after Ive optimized it Ill ask his permission to show it here.
Thats just it, the harmonic spectrum barely changes from low power to full power, even upto 50KHZ full power, Ill show you a 20v p-p plot, Here THD is 0.00024 at 20KHZ, as you can see the amp has extremely low noisefloor, so it can show these levels easily.
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Kean try the amp that Os first built, I cannot recall its name now but its a commercial one, Os can help here, it was in a thread of his and maybe he still has the lt files. I battled to get it stable and when it was, it was far off the commercial unit and had many extra parts.
The low noise floor is a design feature, if you look at any cyrus amp model youll see they heavily emphize low noisefloors too, these amps are highly regarded and the strangest thing about them is that they have very undesireable distortion patterns especially from model 3 onwards. It hasnt stoped them from winning awards though.
The low noise floor is a design feature, if you look at any cyrus amp model youll see they heavily emphize low noisefloors too, these amps are highly regarded and the strangest thing about them is that they have very undesireable distortion patterns especially from model 3 onwards. It hasnt stoped them from winning awards though.
Exactly, by manipulating the Ltspice commands, when one doesnt need to do this, what does it tell you of the circuit. Sim some cyrus designs, but dont show them here, anatech wont like it.
No way, so far I have built 6 of them and sold them, theyre are not build friendly, some parts need very very close matching and need to be in thermal contact or you run into problems without DC servo.
No way, so far I have built 6 of them and sold them, theyre are not build friendly, some parts need very very close matching and need to be in thermal contact or you run into problems without DC servo.
Mouser - $0.51 US apiece.
I just bought -
An externally hosted image should be here but it was not working when we last tested it.
for a whole $20 on fleabay , it says power concepts but is really a dual channel hitachi 20mhz underneath.
THEY did not know that ,that's why I won it.!On to this amp , I will make the small signal board small , modular , with smd and the 5 KSA/C's on a small heatsink , board should be 2" X 3" .
With the small board in hand , you plug it in with one of these -
to the power output board.
There will be 2 or more types of power OPS's... Type 3 self , triple , or the LT1166 flavor.
I really would like to get the model for the 1166 but LT does not list it .
If anyone knows where to get it , please tell.
all these secrets... ohhhhhhhh
OS
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