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6C33C cathode follower, slimline power amp (design: Suncalc)
http://diyaudioprojects.com/Forum/viewtopic.php?f=9&t=6013
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Author:  Suncalc [ 30 Jan 2018, 19:39 ]
Post subject:  Re: 6C33C cathode follower, slimline power amp (design: Sunc

KochiyaYamato wrote:
I see zero reason to drop nearly 200v accross the emitter resistors, ...
Well, how about because that's where I chose the operating pont. :D

However, seriously, I didn't just throw a dart at the plate characteristics. I investigated a range of operating regions and chose one that I felt met my design criteria. I will point out that, because of the very low amplification factor of the tube, uncompensated stage distortion was a consideration. And yes, the design dissipates about 35W/channel in the load resistors. But when already dropping about 45W into the filaments for each channel, I was hardly concerned about overall efficiency. And the 300V supply is nice because the 4S driver works really well at this B+ voltage. Serendipitously, if a 12AX7 is selected for the driver tube, the power stage can be driven hard without overall distortion being too high.

As to using a CCS or solid state diode load, I have a very simple reason to not do this; I do not like the resulting harmonic structure. If I want an amp that sound like a solid state amp, I'll design a solid state amplifier. A cathode follower with 100% feedback already has high order harmonic promotion issues. When used as a driver stage, where distortion is already higher, I strive to keep the uncompensated harmonic structure as close to purely even order as possible. This means no active loads.

As to the driver resistors, the power figures are the actual dissipation rounded to a near round value (i.e 6.845W to 7W and 28.1W to 30W). I leave derating of components to the builder since only the builder can know how they are building the amplifier and what build and derating rules they prefer to follow.

And finally...
KochiyaYamato wrote:
This schematic somewhat seems like a scam
Well, perhaps that's because you really don't seem to understand it.

If I may make a suggestion. Since you clearly think very little of my design, perhaps you could specify and design an alternative amplifier topology and schematic and post it here. I am sure that it would be informative. And in addition, this would provide those reading the forum with more options and clearly different perspectives on the design process. I know that I, for one, would be very interested in seeing your design.

Thank you for your comments.

Author:  mwhouston [ 31 Jan 2018, 03:22 ]
Post subject:  Re: 6C33C cathode follower, slimline power amp (design: Sunc

Matt I'll back you any day. You are just driving me forward to building this baby. I have built so many of your designs , think they are great and love them all. Your "Lace Wood", my "Black Lace", has been my main power amp for months now. Love it.

I have sorted my HT issues now but need to finish other projects.

Author:  diyAudioProjects.com [ 31 Jan 2018, 12:26 ]
Post subject:  Re: 6C33C cathode follower, slimline power amp (design: Sunc

Gentlemen - I have deleted a few of the recent posts in this thread for various reasons which are unacceptable to this forum.

We do not refer to schematics which people generously share as a "scam". It is not acceptable to call our members idiots. It is in poor taste to post your schematic (thread jacking) and claim superiority.

While criticism may be tough, it is ok on the form and often necessary. However, the criticism must be constructive/productive and all members need to be treated with respect all of the time.

Author:  KochiyaYamato [ 31 Jan 2018, 15:13 ]
Post subject:  Re: 6C33C cathode follower, slimline power amp (design: Sunc

diyAudioProjects.com wrote:
Gentlemen - I have deleted a few of the recents posts in this threads for various reasons which are unacceptable to this forum.

We do not refer to schematics which people generously share as a "scam". It is not acceptable to call our members idiots. It is in poor taste to post your schematic (thread jacking) and claim superiority.

While criticism may be tough, it is ok on the form and often necessary. However, the criticism must be constructive/productive and all members need to be treated with respect all of the time.

I'm not claiming superiourity, I'm just saying best amps need some sort of feedback in someway to get best sound, I am not intrested in sharing my best schematics. In a diffrent way
Furthermore my schematic is not scam, you can see by the ammount of info and thought I put into it. Scam means posting a schmatic and explaining nothing about how it works.

A cathode follower doen't have any feedback loops reducing distortion. Nor is it able to feedback, because this requires a inverting input, or a inverted signal feedback into a non invert input. Or non invert signal feed into invert input of the cathode follower.
Another reason why cathode follower is zero negative feedback, cathode follower dosen't have any open loop gain, to half the distortion the openloop gain needs to be halfed.

I wanna sell my best amps one day if able to, sharing online means otherbuilds it for free or even patten it, that thakes the chance away.

Author:  M. Gregg [ 31 Jan 2018, 15:23 ]
Post subject:  Re: 6C33C cathode follower, slimline power amp (design: Sunc

Quote:
Scam means posting a schmatic and explaining nothing about how it works


I think your definition varies from what others think.

Scam means deception, or in this case inferring posting a circuit which does not work.
Obviously its quite a sweeping statement.
I,m sure there is no intent to deceive anyone.

The other point you make
Quote:
I'm just saying best amps need some sort of feedback in someway to get best sound


There is a massive topic of discussion about feedback and its a very awkward subject in audio circles.

To be honest, I think that if Suncalc has made the effort to design an amp using 6c33c tubes then he deserves a pat on the back.
I have used these tubes and found them very strange to work with, just the heat alone needs extensive thinking to control temperature.
They also have a strange problem with thermal runaway after bias setting, and they can and do flash over.
All quite weird.
Just for interest the bias type has a marked effect on the overall sound.

Regards
M. Gregg

Author:  KochiyaYamato [ 31 Jan 2018, 15:46 ]
Post subject:  Re: 6C33C cathode follower, slimline power amp (design: Sunc

My schmatic should work, however I don't own any 6c33c.

Suncalc wanted to see a 6c33c cathode follower so I spent a hour or two designing one from scratch.

Fruthermore, my schematic other than having a fixed stable bias controled by the constant current load. The only advantage would be a cheaper build and lower voltage.

Suncalc's schematic would sound equally well or better because the valve voltage is higher than mine 70-80v vs 100-120v, its virtuially equivlant to a constant current load, approx 200v drop on emitter resistors, we know max swing is less than 16v. 200/(200-16) The change in current wihout load and 16v swing is less than 9%. Change in current means distortion, if there was only 10v accross resistors this means the valve may operate below 0.1Amps when listening and have allot of distrion, refering to load line graph below 0.1A lots of distortion.

Author:  M. Gregg [ 31 Jan 2018, 15:54 ]
Post subject:  Re: 6C33C cathode follower, slimline power amp (design: Sunc

Quote:
however I don't own any 6c33c.


The 6c33c does not follow what you would think regards sound and design.
Did you take a look at:
http://www.goodsoundclub.com/Forums/Sho ... ostID=6140

Regards design,

Many people hate negative feedback, many think all triode is best etc, and so it goes on with things like starvation etc.
If you are designing for a piece of wire with gain, then you might find what people think sounds good to be very variable.
I thought mixed bias sounded the best, but there are other ideas.

Regards
M. Gregg

Author:  KochiyaYamato [ 31 Jan 2018, 16:05 ]
Post subject:  Re: 6C33C cathode follower, slimline power amp (design: Sunc

Another point on my schematic is that it should have a higher power output because the valve voltage is lower.

I tried zero nfb amps, also tried designing my own amp which has absolute zero negative feedback.
I don't see any plorbem with nfb and It always sounded better.

I had a skim through the page you linked me to.

Author:  M. Gregg [ 31 Jan 2018, 16:09 ]
Post subject:  Re: 6C33C cathode follower, slimline power amp (design: Sunc

Just curious,

What do you think of Ongaku and design philosophy?

Regards
M. Gregg

Author:  KochiyaYamato [ 31 Jan 2018, 16:16 ]
Post subject:  Re: 6C33C cathode follower, slimline power amp (design: Sunc

Well I am doing things diffrently from others to start with. If the schematic is similiar then theres no way in being sounding much better.
I'm doing things in a self taught mannner, building and testing to see the effects of diffrent schematics real life. I went through allot of youtube vidoes on building blocks which helped.
It would be helpfull if I did transistors and or valves at university.
I'm only doing audio because for some reason able to get very good sound by messing arround, its the beaufiull results that keeps me doing it.

However they don't offer this kind of course at my university, they offer microcontolers and I have a quite realistic idea on using microcontrolers to make big money.

I've read about the site where it says the bias is very low when the valve is cold and it takes 30-40minutes to stabalize, in case of a constant current load, this may mean that there isn't any sound during first 5-15mins.
Because the cathode to grid voltage is either postivie or very small. The valve should stay at a bias current controled by ccs though.

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