you could use one triode to drive both 2A3's instead of two (and leave the other half unused...not trendy...) or each section driving each 2A3 but nothing would change it could actually get worse...
Ah ok, I didn't know details. Have you seen one,yet?
Yes, this is another secret of this amplifier. But if you build it without this, and use inexpensive iron then the circuit quickly loses fascination.
Don't forget that the 2nd poster dug this thread out of the murky depths because of the schematic, which alone is (quite frankly) not so special.
Not really true. They are both low impedance and power requirements are still modest. Compromises or much higher cost for the same result come in other circumstances. I would agree if we were comparing a 2A3 PSE and a 300B SE, the former being much more conveninent and not just because of the OPT.
From first hand experience, I can easily state that it is less work to design and build a 1.25K OPT than a 2.5K OPT.
Putting 2a3 and 300b in the same sentence is really not fair. This thread is really going nowhere fast. sorry, I am out of such useless discussions.
I must place the blame (again) on the 2nd poster who dug this discussion out of the nebula where it was.
I was talking about the Neiro.
For the rest the cathode follower works just as good. You can use a cathode follower, properly implemented, also for driving a current sucker like a transmitting triode biased with positive grid without ANY problem. Zero.
So you can you use a FET every time if you like but it doesn't make it better for everyone.
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Unfortunately for you I know how to design and make a transformer.
The work to design them is certainly the same, unless you don't know the math and physics behind. To build them there is little difference unless you use casual equipment. The impedance alone is misleading because the power rating will not be same as one is intended for a 4W amp and the other for 8W amp. It makes quite a difference in comparison to a situation where they would have the same power rating.
Why????? That's exactly the reason why the original AN amps below 20W were all PSE. The 300B will be a competitive choice when used in PSE for 20-25W output power. Competitive includes complexity and cost.
If you say so...
I'm not sure what you're talking about, the circuit uses 5687//5687 to drive 2A3//2A3. You could use whatever you like of course, what are we actually talking about here?
You sounded pretty certain about it when you said it was a pair of mono amplifiers with 5687 drivers...
Yes, the amplifier has been out for a couple of years now, have heard one on several occasions and it always was truly excellent. Every review I have read also says the same. My own build has confirmed also that PSE2A3 can be very good.
Attached is a pic of the Neiro replacement, a long with the schematic of the Neiro amplifier
If we are still talking about the same circuit, to use a (MOS?)FET you would need to rework the bias network for the output stage which is incorporated in the cathode circuit of the driver, and then you have a different amplifier.
If you were wanting to remove the CF, I can suggest finding a way to use a similar sort of split rail driver supply (or similar enough) and drive the output stage with a plate loaded low mu DHT... (back to the original topic!!)
Now I am confused, first you say that the the circuit is 'fascinating' and then you say that it is simply 'not so special'.
Yes.
Not necessarily.
Probably yes.
Good decision!
🙂
L.H/S
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I was talking about the driver. About the 2A3 it is certain that at any given (useful) level the PSE will distort less, if properly done.
I am only certain about the philosophy. The actual Souga circuit I have never seen it. I knew of its existence because I was told. The Neiro I know.
@Soulmerchant
LOL! He USED "today's" parts dude. He died just a few years ago. The Ongaku was the first amp, which came out in the late '80s/early '90s. Everything else came after.
And as we are all talking about using 80 year old technology, tubes, what has changed in the past few years?!
LOL! He USED "today's" parts dude. He died just a few years ago. The Ongaku was the first amp, which came out in the late '80s/early '90s. Everything else came after.
And as we are all talking about using 80 year old technology, tubes, what has changed in the past few years?!
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biasing techniques WRT direct coupled circuits - you can read about them in my Nobel Prize summary.
3/4 serious.
LH/S
3/4 serious.
LH/S
Today we have many excellent ways to regulate current and voltage that were simply not available when Kondo San began his designs. And his designs remained very much the same over the years.
Because they were "perfect" designs? If you think that is the answer, then you have bought into the entire Kondo marketing cult. And believe me, there was a LOT of marketing going on in the 80's and 90's...
Here is a fair challenge: use any of Kondo San's designs with cheaper "iron" and see how they perform.
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btw, I have build a great many 2a3 amplifiers. I started using Kondo designs. Then I realized that a single 2a3 was much better than a pair of them. Then I got down to using just the 45.
Now I use many different types of DHT's, depending on the requirements and parts on hand, but Kondo is definitely a very good starting point.
Now I use many different types of DHT's, depending on the requirements and parts on hand, but Kondo is definitely a very good starting point.
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