25W Class A amp with Lateral MOSFETs - Page 13 - diyAudio
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Old 14th March 2016, 10:06 PM   #121
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Quote:
Originally Posted by Guitar.mod View Post
Nice Work!

p.s. Little note: gate stopper resistors should be as near to the gate as possible.
In Your version - these are as far as possible
Also low power signal "GND" shares same trace as power "GND", this practice should be avoided. It should go with separate traces to star gnd poi1nt.
I agree. This PCB was designed some year ago, and in speed. Though, I made amp with that PCBs and.. In a very serious system, with serious source, serious speakers and sound absorbers and diffusers - this amp shined like a true star... So I decided not to make new modified PCBs
In a link I provided you can download Eagle PCB files and everyone is free to modify PCB as long as they want...

No, there is no BUMP (as Juma said, obviously), there is just some wait time for output cap to fill with electricity before the pop-rock starts.

If you gonna make this amp, although it work very fine with bias of 500mA, I recommend making it as specified, with 1A3 bias - it will shine even more...
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Old 14th March 2016, 10:54 PM   #122
Jay is offline Jay  Indonesia
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Quote:
Originally Posted by Guitar.mod View Post
p.s. Little note: gate stopper resistors should be as near to the gate as possible.
In Your version - these are as far as possible
Also low power signal "GND" shares same trace as power "GND", this practice should be avoided. It should go with separate traces to star gnd point.
This is actually better implemented than most amplifiers here It is hard to achieve good result without understanding the issues and how to avoid them. Many people just follow the "golden rules of thumb" and still the result is not good. As an example, sometimes "star grounding" is used only to make things worse.

Besides, this is single ended with CM regulation.
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Old 15th March 2016, 07:18 AM   #123
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Quote:
Originally Posted by juma View Post
I thought it was obvious that there is no turn on/off thump.
Quote:
Originally Posted by acamilicko View Post
No, there is no BUMP (as Juma said, obviously), there is just some wait time for output cap to fill with electricity before the pop-rock starts.
Dear Juma and Acamilicko, thank You! When I made some years ago LM1875 (single supply with output cap version) - there was very huge and slow, harmful bump.

Quote:
If you gonna make this amp, although it work very fine with bias of 500mA, I recommend making it as specified, with 1A3 bias - it will shine even more...
I think that bias 400-500mA should be enough. Also I am thinking about F5 with BJT input simple version similar to "TSSA". It's advantage - Output with gain - we have more headroom with same power supply voltage, less wasted power.
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Old 21st August 2016, 05:53 PM   #124
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Default miniversion

Quote:
Originally Posted by acamilicko View Post
Yeah! Totally agree
Such a quality amplifier, amaizing.. Totally forgotten without reason. So simple construction, and so precise sounding amplifier, a lot of details and in the same time pretty transparent - CLASSY AMP!

I've built "mini" variant starting with 200mA bias, and ending up with 500mA - good for these heatsinks. With half of ampere bias it sounds a lot better than low bias, and as Juma says, it shouldn't be less to achieve good sound.

Slim pcb version>
Click the image to open in full size.

Eagle pcb files> http://www.diyaudio.rs/index.php?app...ttach_id=38642

More images and process of work here: Projekat: SVAJA - Stranica 6 - Solid State - diyAudio.rs

Click the image to open in full size.

Thanks Juma!
Aleksandar,

I wonder, if the only "change" for your miniversion is the reduced current?

cheers Ernst
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Old 21st August 2016, 07:44 PM   #125
pchw is offline pchw  United States
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Can someone attach the pdf and the Eagle files here?

Thanks!!
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Old 19th June 2017, 12:48 PM   #126
Skorpio is offline Skorpio  Denmark
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Could this amp be easily "upgraded" with positive feedback, as the F7?
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Old 19th June 2017, 05:39 PM   #127
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I think so. It's pretty easy to do, just check Lhquam's posts with formulas
for most (or all) the variations you might want.
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Old 20th June 2017, 07:01 AM   #128
juma is offline juma  Germany
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Quote:
Originally Posted by Skorpio View Post
Could this amp be easily "upgraded" with positive feedback, as the F7?
It's very different from pre-PF F7 (which is basically slightly modified old Zenotron amp) so it won't necessarily be an upgrade, but it will bring a change in performance for sure.
You'll get more distortion an somewhat higher damping factor, depending on how much positive feedback you use. You won't know how it sounds before you build it and be prepared to experiment with PF until you find what you like.
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Old 20th June 2017, 07:16 AM   #129
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Hi juma

Since you've mentioned the zenotron can I ask what you think of it?

I've always had in mind to build one of your designs but never had quite the right parts or level of skill (since I will be hard wiring it) but I have everything for the zenotron.

Plus my old ears ain't what they used to be.

Thanks, sp
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Old 20th June 2017, 08:30 AM   #130
juma is offline juma  Germany
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Zenotron is OK but it can be easily improved without added complexity - see this:
Cubie - small F5 variant with GR grade JFETs and LatFETs
or, even better, this:
Cubie2

Threads are not very long, read them and see if something fits the bill...
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