I was thinking about the possible need for buffers to make the crossover sections work as intended. You might not want to put regular RC filters between a 6C45 VAS and a bunch of mosfet output stages without some cathode/source/emitter followers to deal with the impedances.
I would at least put something between the VAS and the filters.
I would at least put something between the VAS and the filters.
"I was thinking about the possible need for buffers to make the crossover sections work as intended. You might not want to put regular RC filters between a 6C45 VAS and a bunch of mosfet output stages without some cathode/source/emitter followers to deal with the impedances.
I would at least put something between the VAS and the filters."
I was going to use a source follower on the output of the VAS, and another on the output of the midrange attenuator.
Was thinking about using the woofer follower as part of the filter so as to get a 12dB Q=1, the others to be 6dB.
I would at least put something between the VAS and the filters."
I was going to use a source follower on the output of the VAS, and another on the output of the midrange attenuator.
Was thinking about using the woofer follower as part of the filter so as to get a 12dB Q=1, the others to be 6dB.
Well, thats one of two big amps. Monoblocks, you see.
Nope, no noise yet. So far this is nothing but a power transformer and a bunch of chokes attached to a heatsink.
The funny thing is that there will be no real chassis for these amps, I´ll just hardwire everything onto the heatsinks.
The amps will be standing upright with two feets under the heatsink and one under the transformer.
Nope, no noise yet. So far this is nothing but a power transformer and a bunch of chokes attached to a heatsink.
The funny thing is that there will be no real chassis for these amps, I´ll just hardwire everything onto the heatsinks.
The amps will be standing upright with two feets under the heatsink and one under the transformer.
I could get hold of two 35mH chokes with 20A current rating.
I would use it for a little single ended amplifier with 15-20V supply and around 2A bias.
It has relatively high DC-resistance of 1.2Ohm.
Do you think it´ll suit my needs?
TIA!
Jens
I would use it for a little single ended amplifier with 15-20V supply and around 2A bias.
It has relatively high DC-resistance of 1.2Ohm.
Do you think it´ll suit my needs?
TIA!
Jens
Is that rating 20A DC or AC?
I doubt it´s DC if the resistance is 1,2 ohms.
How do they look, are they iron cored with airgaps?
I doubt it´s DC if the resistance is 1,2 ohms.
How do they look, are they iron cored with airgaps?
The pic doesn´t say anything about the size of those chokes but I doubt they are rated 20A DC. The wire seems a bit thin for that.
Ask Walter ir they are airgapped. If not, they´re useless.
Anyways the inductance is too low for 8 ohm loads (for fullrange operation, that is) but should work for 4 ohm.
Ask Walter ir they are airgapped. If not, they´re useless.
Anyways the inductance is too low for 8 ohm loads (for fullrange operation, that is) but should work for 4 ohm.
Will do.
Well, it is intended not as my main amplifier.
Maybe a little PC amplifier or for my second system.
I´m thinking in terms of ~10W and will connect some ineffecient Magnat speakers with one of those strange 4-8ohm ratings.
Mmmmh, maybe it´s not worth all the trouble to gain a bit in efficiency. Maybe I should just burn a few more watts and build a simple voltage follower with fet ccs.
But it´d definitely be a fun project.
But about the current rating: I mean I won´t need 20A DC anyway. Important is just that it doesn´t saturate too early or am I wrong?
Cheerio
Jens
For such a small amp intended for PC use you might as well use a CCS instead. Of course chokes are fun to play around with but they also has some problems related to them.
One is that you can´t use direct coupling between input and output stage, at least not easy.
For an 10W @ 4 ohms CCS loaded follower try +20V and 2,5A bias.
Current rating and saturation: The current rating is, as you say, not very important. Saturation depends on the airgap and is very important.
One is that you can´t use direct coupling between input and output stage, at least not easy.
For an 10W @ 4 ohms CCS loaded follower try +20V and 2,5A bias.
Current rating and saturation: The current rating is, as you say, not very important. Saturation depends on the airgap and is very important.
A while back I built a 5 watt SOZ but replaced the lower resistors
with a CCS. It sounded just lovely with the speakers I was using. Now I am thinking of replacing the 8 ohm load resistors with inductors (20 mh , 2 ohm) just for my mids. But how do I calculate the output resistance ?
Thanks,
Woody
with a CCS. It sounded just lovely with the speakers I was using. Now I am thinking of replacing the 8 ohm load resistors with inductors (20 mh , 2 ohm) just for my mids. But how do I calculate the output resistance ?
Thanks,
Woody
thanks again Fuling for advice!
Will probably really build a small voltage follower.
Something like Andrea Ciuffoli´s hot follower with dynamic current source or let´s say a zen amp without gain.😉
Cheers
Jens
PS.: The chokes have an airgap. Some piece of paper there.
For anybody still interested.
Will probably really build a small voltage follower.
Something like Andrea Ciuffoli´s hot follower with dynamic current source or let´s say a zen amp without gain.😉
Cheers
Jens
PS.: The chokes have an airgap. Some piece of paper there.
For anybody still interested.
I read somewhere that the dynamic current source ruined the sound, but you´ll never know unless you try it.
Also, have a look at the mosfet follower at Rod Elliots page. Very simple and straightforward.
Woody: I don´t know if the "choke loaded Soz enigma" ever has been solved, I have never seen any complete schematics or calculations. Choke loaded gain stages seems so be a bit complicated.
Also, have a look at the mosfet follower at Rod Elliots page. Very simple and straightforward.
Woody: I don´t know if the "choke loaded Soz enigma" ever has been solved, I have never seen any complete schematics or calculations. Choke loaded gain stages seems so be a bit complicated.
woody said:
I don't believe you have to. You can load the SOZ with
any combination of resistance and inductance that you like.
The gain of SOZ will probably go up with inductors, since the
load becomes an even more dominant factor, but so what?
It won't change by that much, and the damping factor was
always very low anyway, so you don't need to get too excited
about that.
If you're worried about flyback voltages, just put something
like 16 to 22 ohms in parallel with the inductors.
I have a neat little version of SOZ using coupled inductors, which
will be along shortly, using a version of X (SuperSymmetric)
feedback, and it works very well.
😎
I've never looked at anything like this before but I'd hazard a guess that the extreme quality of sound noted is largely tied to the inductor. An inductor, specifically air cored ones have a very high quality of complex HF LCR . Any inductor is good, but the sonics can be slurred due to what we like to call Inductive Reactance which is really transverse wave function in disguise, as noted in transmission line calculations. In this case it is due to the steel laminate or whatever core. Air core is best, if you can do it. Dynamics should be exceedingly linear in this type of circuit, which is why such things are favored in tube circuits, via their very design. Feel free to slap me about if you feel I am wrong. Sorry if the babble seems incomprehensible, it is ..what it is...
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