Ok, this little mystery about your not so square, square wave got the better part of me, so I decided to throw the same amp together as you have, just with a 160mH air core and 4.700uF lytic and 50uF film on the output.(ok I had most of it laying around from my previous test setup).
My memory seems to fail me, as my square wave also has some angle, but it's like the pic you posted. At the lowest freq. of interest to me, which is 30Hz, it still looks reasonable, and the sine looks near perfect.
I tried listenig using Fostex FE166e units in Abbey clones (96db/w), this setup went all the way, though the bass was better and the noise floor lower, from my diff. cascoded pair version.
Magura 🙂
My memory seems to fail me, as my square wave also has some angle, but it's like the pic you posted. At the lowest freq. of interest to me, which is 30Hz, it still looks reasonable, and the sine looks near perfect.
I tried listenig using Fostex FE166e units in Abbey clones (96db/w), this setup went all the way, though the bass was better and the noise floor lower, from my diff. cascoded pair version.
Magura 🙂
Do you have a schematic of your differential, cascoded amp? Are you making a cascoded, diffential amp with the inductors loading the collectors of the differential amp?
davidallancole said:
No, I don't have a schematic of the current mutation of the diff. cascoded, inductor loaded amp. It is still under development, as I am experimenting with thermal control of the JFET's.
As this is a MOSFET based amp, the load is on the drain...
Take a look at the Zen v7 and Zen v9 articles, and you will see what I'm talking about.
Magura 🙂
Magura, did you notice that in a single ended inductor loaded amp, the limiting factor will be ~twice the voltage rail, while in the differential circuit the limiting factor is not the voltage rail but the quiescent current?
Well, your assumption is a truth with modifications 🙂
The limiting factor for single ended, is not quite twice the rail voltage, but closer to 125 to 150% of the rail voltage IRL.
The differential circuit ran into voltage limitations too before it ran out of steam.
Magura 🙂
The limiting factor for single ended, is not quite twice the rail voltage, but closer to 125 to 150% of the rail voltage IRL.
The differential circuit ran into voltage limitations too before it ran out of steam.
Magura 🙂
flg said:Air Ha
Yeah, air!
Actually I think it's the fresh countryside air I am surrounded by around here 😉
Dry your eyes
Don't you have a spool of wire? I do realize it will not be impregnated with fresh countryside air, but that aside it should be just as good for the purpose....
Magura 🙂
As regards the frequency response of the amp this thread is all about, seeing the load is in the drain circuit, and especially seeing it is a cascode circuit, the output impedance will be very high. It is pretty much a current source so the output voltage is completely at the mercy of the load impedance. If that impedance changes with frequency then so will the voltage...
The output impedance will be almost completely under the control of the amount of negative feedback.
Someone mentioned putting a low value resistor across the choke to prevent ringing. I've got a 10R 2W + 100nF in series in mine.
Lastly, if the load was across the choke instead of across the mosfets then there would (probably) be no switch-on bump and also you could use a lower voltage coupling cap.
The output impedance will be almost completely under the control of the amount of negative feedback.
Someone mentioned putting a low value resistor across the choke to prevent ringing. I've got a 10R 2W + 100nF in series in mine.
Lastly, if the load was across the choke instead of across the mosfets then there would (probably) be no switch-on bump and also you could use a lower voltage coupling cap.
Circlotron said:Hey! I just discovered this thread and then straight away it comes to a dead stop.
I hate to tell you this, but I think it's something personal 😉
Magura 🙂
Hi!
One time Fuling asked this, but nobody answered yet:
Anyway, is there any literaure of Choke loaded amp designing??
Greets:
Tyimo
One time Fuling asked this, but nobody answered yet:
Anyway, is there any literaure of Choke loaded amp designing??
Greets:
Tyimo
The large choke in the class A were already wound and I only reduced the gap to get a higher inductance. They are not impregnated at all. Neither were the ones I made out of microwave oven transformers. I didn't actually do anything with those ones - just made them and looked at them.
Circlotron said:Hey! I just discovered this thread and then straight away it comes to a dead stop.
Well, I'm glad your not blaming me
I've been a little busy with some racing and other interests. I have played with the gap on my inductor core to try to raise the inductance without promoting to much lower saturation. I need to try a little more gap and see how that performs??? I have also been playing with R loading and different Iq's to examine the charateristics of Voltage gain, as in VAS, or preamp, or headphone amp. I'm also going to try a Pathos style, L loaded EF amp. It will be interesting to see the performance with EF vs the cascoded JFET gain stage loading???
😀
Magura!
Would it be possible to use Led bias for the Mosfet? (irfp240)
BTW: How do you like your amp???? Did you campared with a "stock" ZV9?
Greets:
Tyimo
Would it be possible to use Led bias for the Mosfet? (irfp240)
BTW: How do you like your amp???? Did you campared with a "stock" ZV9?
Greets:
Tyimo
Tyimo said:
Why would you use LED bias ( I assume you mean LED ref. CCS)?
This is an easy question to answer, cause I don't like the upper end from amps with the aleph style active CCS. The bottom end is about the same with for both of them.
Magura 🙂
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