I stumbled across this design by Andrea Ciuffoli . Does this type of design require a good voltage source (BOZ or something else?) like the Power Follower 99c. It looks like a fairly straight forward design, just couldnt find too much info about it. The 2SC3264/2SA1295 seem a little harder to procure.
Attachments
Not an original design really. Still fighting with my implementation.
You will have trouble at higher currents in the form of compression. The bias will be stable and high.
-Chris
You will have trouble at higher currents in the form of compression. The bias will be stable and high.
-Chris
Isnt this a good thing? The sound becomes compressed in this design as the bias current goes higher or if your driving low impedance loads?
Hi MEGA-amp,
No, it's not a good thing. IT doesn't sound good. At low volumes, that circuit sounds good, when you start getting peaks or a bass line in the music, the sound deteriorates.
As I said, I am still trying to make this sound good.
Bias, at low volumes the heatsink temperature is much higher than at higher volumes. The bias current has remained constant on my experimental units.
-Chris
No, it's not a good thing. IT doesn't sound good. At low volumes, that circuit sounds good, when you start getting peaks or a bass line in the music, the sound deteriorates.
As I said, I am still trying to make this sound good.
Bias, at low volumes the heatsink temperature is much higher than at higher volumes. The bias current has remained constant on my experimental units.
-Chris
Well that may explain what he says at the end of the amp description: "WARNING: designing phase so some parts could be change in the next days!" Dont know how long its been posted. What do you have driving it? I'd like to try it with just a bridge/cap supply to see how it sounds, but those Sankens are pretty darn expensive. Some details about the schematic are missing too. This is new territory for me.
Thanks.
John
Thanks.
John
Hi John,
One never knows. It's only a diamond buffer using power transistors. Nothing really special. Mine has more parts but suffers the same short comings. It has been a learning experience for me.
A commercial design that is related would be a Marantz 300DC. I own one and it sounds good. But only due to a high amount of feedback.
It's an easy circuit, why no build it and experiment?
-Chris
One never knows. It's only a diamond buffer using power transistors. Nothing really special. Mine has more parts but suffers the same short comings. It has been a learning experience for me.
A commercial design that is related would be a Marantz 300DC. I own one and it sounds good. But only due to a high amount of feedback.
It's an easy circuit, why no build it and experiment?
-Chris
Hi, Chris,
This is exactly what I'm thinking about when seeing diamond buffer output stage. So, it is happening, the current is kind of "limited"? I think DartZeel also experiencing the same thing.
300DC or LC's discrete End Millenium (the first one) is quite different. They use diamond buffer until the driver, the output stage can have all the current they need, the current restriction only up to the drivers. Am I right about this tought?
This is exactly what I'm thinking about when seeing diamond buffer output stage. So, it is happening, the current is kind of "limited"? I think DartZeel also experiencing the same thing.
300DC or LC's discrete End Millenium (the first one) is quite different. They use diamond buffer until the driver, the output stage can have all the current they need, the current restriction only up to the drivers. Am I right about this tought?
The current feeding the output transistors came only from the CCS, as the input transistors can't source any current into the outputs..
Hi lumanauw,
The 300DC is a modified diamond buffer with more components added for current protection and better bias behaviour, since the drivers and pre's are not mounted on the heatsink.
The drivers and outputs are supplied via a resistor to the supply rail. The predriver shunts some of this current away, just as in a diamond buffer stage. This design is very sensitive to the vbe drops in the outputs and drivers. Also in the emitter resistors. The only way to make it sound good when delivering large amounts of current is with high feedback factors.
For low current applications, this circuit is great!
-Chris
The 300DC is a modified diamond buffer with more components added for current protection and better bias behaviour, since the drivers and pre's are not mounted on the heatsink.
The drivers and outputs are supplied via a resistor to the supply rail. The predriver shunts some of this current away, just as in a diamond buffer stage. This design is very sensitive to the vbe drops in the outputs and drivers. Also in the emitter resistors. The only way to make it sound good when delivering large amounts of current is with high feedback factors.
For low current applications, this circuit is great!
-Chris
Well I'll give it a hack, its diy, why not.
I mostly listen nearfield with the music rather low, dont need gobs of current or wattage.
What could I use in place of the recommended 2SC3264/2SA1295 devices? Some missing resistor values may help too.
Thanks for the input.
John
I mostly listen nearfield with the music rather low, dont need gobs of current or wattage. What could I use in place of the recommended 2SC3264/2SA1295 devices? Some missing resistor values may help too.
Thanks for the input.
John
MEGA-amp said:
The value of the missing resistors , depend of the value of the maximal output current , that you want to be passing through the outputs.
You could build this with about any suitable devices.
Try adding the cap from the cool follower design, it will then transition into class AB for the peaks.
Try adding the cap from the cool follower design, it will then transition into class AB for the peaks.
Hi John,
Djk is right. I've built them with different devices and it always works. You will have to play with resistor values to set the bias current and things like that.
-Chris
Djk is right. I've built them with different devices and it always works. You will have to play with resistor values to set the bias current and things like that.
-Chris
Info
Just to explain some points:
- The Power Follower is a complete project tested by many people in the world and it gives an incredible sonic performances if driven with a correct voltage amplifier stage.
Someone prefer it to a SE 300B amp and to the ZEN amp.
- The Hot Follower is only an idea and I don't' have tested it.
This will give a good sound but cannot be compared to the Power Follower because this is a normal Push-Pull design.
Just to explain some points:
- The Power Follower is a complete project tested by many people in the world and it gives an incredible sonic performances if driven with a correct voltage amplifier stage.
Someone prefer it to a SE 300B amp and to the ZEN amp.
- The Hot Follower is only an idea and I don't' have tested it.
This will give a good sound but cannot be compared to the Power Follower because this is a normal Push-Pull design.
Re: Info
Dear Sir,
is a complete schematic of "THE POWER FOLLOWER" available somewhere in the net?
I am very much interested in high current follower having already nice voltage gain stages to test.
After your wonderful comments I am more excited than ever !
"Preferred to a SE300B and to a ZEN amp": this really means something to me.
Please give me some more information on the "TPF".
Thank you so much.
Kind regards,
beppe
audiodesign said:
Dear Sir,
is a complete schematic of "THE POWER FOLLOWER" available somewhere in the net?
I am very much interested in high current follower having already nice voltage gain stages to test.
After your wonderful comments I am more excited than ever !
"Preferred to a SE300B and to a ZEN amp": this really means something to me.
Please give me some more information on the "TPF".
Thank you so much.
Kind regards,
beppe
look this webpage
http://www.audiodesignguide.com/PowerFollower/index.html
on my website
http://www.audiodesignguide.com
http://www.audiodesignguide.com/PowerFollower/index.html
on my website
http://www.audiodesignguide.com
audiodesign said:
Dear Sir,
thank you sincerely for your extremely kind and valuable reply.
Just to be sure the schematic you propose is the one I am attaching?
Do you think that with a dual power supply I could go without the coupling cap at the output?
What is your opinion on the influence of that cap ?
Thank you so much.
Kind regards,
beppe
Attachments
Tube_Dude said:
Exactly, so the CCS current should be quite high (which gives a whole new meaning to 'hot' follower).
Unfortunately, the only new and never seen thing in that design are the capacitors from the CCS sensing transistor collectors to ground, which, at power on, give a nice current spike through the whole thing. Increase the capacitance sufficiently and various pieces of the follwer will go up in smoke. Also, they completely ruin any semblance of PSRR for the follwer - more than 0.7V ripple on the power rails shuts down the corrsponding CCS completely. Unfortunately, such features are not rare in Andrea's designs 🙁
ilimzn said:
Yes...and in this last schematic (post # 18 ) , I also don't like to see the input ground connected to the positive rail , because the source of the Mosfet is referenced to the minus rail..
Look at the same subject here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=73598
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