The Very Best Amplifier I Have Ever Heard!!!!

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#101
A little mechanical support at the top is a good suggestion. You can never have too much support.
Are the speced devices really that critical?
The thread starter has given his kudos to this amp. I think that should be a great start for beta analysis.

Tad
 
#102
NagysAudio said:
80V is way bellow the rated 140V. How can there be any problem? I guess I'm still not sure on what you mean.
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When One of the transistors is FULL ON the other is at cutoff hence the Rail TO Rail voltage will be seen across the one in cutoff... Please someone correct me if I am wrong...

TESTING is important, but who is first to stick out his or her neck for the guillotine, hehehe.

I would have like to have seen a 4 pair board, but the one here is so so so excellent I just might give it a shot.

Can someone say something to at least putting a ground plane on the front end since this is a High Bandwidth amplifier? Please take me to school as to the pros and cons...I would appreciate understanding the topology, no pun intended...

Is there a way to coax out the PDF a 1:1 image to get a laser printed etch pattern as it is presented?

Thanks
 
#103
apexaudio said:
Zeners 12V and diodes 1N4148 wrong (reverted) polarity.
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Do not ignore techical suport, U need it if you want funtional amp at the end. U work 10years in audio industry as a salesman, I build amplifiers 25years. This schematics is copy of some 20years old amp, and can be upgrade with modern parts, post amp pictures it will help for reverse engeenering. Wahab give good suggestion about rail voltage, and it is basic electronic.
Regards and good luck
 
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#104
I would stay well below +-60V
more like +-50V
100watt is plenty power

why suggest more anyway ?

if you want it to perform well, it should be able to handle speakers below 4ohm
so, at least look at realistic output in 3-4ohm
how much can realisticly sized heatsinks dissipate, etc
 
#106
This amp has been tried and tested. There's no need for anyone to knock its design. If using the correct original parts, this amp will function with a circuit board half as good as the one Alex has created.

For anyone to suggest that a 140V transistor can't take 80V rail supply is complete nonsense. This amp is designed with an 80V supply in mind. If you want to use 60V, or 50V please do so. I will most certainly be using an 80V supply.

apexaudio - I happen to be an engineer. The Zeners and diodes in my original schematic are connected the right way. Please view the original schematic before questioning my background, or experience.
 
#107
NagysAudio:

What ever credibility you may have had was totally Dismantled by your last post. I don't have a lot of knowledge about somethings, and I am willing to learn. I hope you learn something here. I feel you have good intentions but your stating you are an Engineer and seeing your lack of fundamentals of Power Amp topology SHOUTS of your need to take heed of what most here have to share in the way of knowledge. I have learned a lot just reading threads. I suggest you do the same. I have NO malice toward you now or before. Stick around and OPEN your mind up, knowledge is wonderful.

Peace and such.
 
#113
Yes , discuss the design. It (the design) was made with profit in mind. It can be much better. Take , for instance, the voltage stage power supply. (pix 1) is the one I will be feeding my capacitance multipliers. It uses a common 48v CT -20VA PCB mounted trafo which you can either double or triple in the circuit below. This voltage stage on this amp or mine (which are similar) ,will use no more than 20 mA per rail so both channels can be powered at once by the circuit.

This amp can be better than the original ... this is DIY , we can go "anal" with it. 😀
OS
 

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#115
I think one more pair is going to make this an BERRY BERRY good power amplifier.

ONE must be sure of his or her output DEVICES are up to the complex speaker loads of TODAY...

Now if we can get a certain Excellent PCB layout "Artist" to work that special magic.........
 
#116
One more pair (at least) seems like a good idea. Remember, the original had TO3 outputs and now we are substituting TO3p's ---probably not as good at dissipating heat as the originals. Also probably a good idea for someone with good testing tools check out the design before a big group buy is organized. We seem to be in a big rush on this one, based on one opinion.
 
#117
I'm going to comment on this one more time, so that the people who are interested in building this amp can have an ease of mind. Please remember, this is a tried and tested amp design and some of the comments have been nonsense. I will no longer be interested in repeating this information if misleading statements continue to be made. So here it goes:

1.) The 12V Zeners and 1N4148 diodes are most DEFINITELY CONNECTED CORRECTLY in my original schematic on page one.

2.) It's perfectly safe to run a +/- 80V power supply with these 140V rated MOSFETS.

This is an incredibly good sounding amplifier. I'm interested in building a pair or two myself, because of the amazing job that Alex did with the PCB.
 
#118
Just because it's a tried and tested design doesn't mean the PCB will be perfect. Lots of other experts around here as well and you act like everyone is supposed to take your word as an absolute truth to all.

With a +/- 80V supply isn't the swing between the rails 160? That's what I thought they were talking about that 140V mosfets shouldn't be run with 160V swing. Maybe I've misunderstood though.
 
#119
Dougie085 - What I meant is that the schematic is tried and tested. It definitely works great! Of course the PCB board might need a change here, or there, but that's something that one can test and see during the construction of the amp. Alex's PCB board looks terrific though. There's nothing that jumps out as a potential problem.

Honestly, I'm not sure what the issue is regarding the power supply voltage. To me it's a non-issue and I'm going to move on. If someone wants to run it with a lower voltage, please do so. I'm excited to build Alex's board.

I've been going through my papers and double, triple, and quadruple checking everything to do with the schematic. The way it's posted it's virtually 100% correct. However, I forgot to include the Zobel filter on the output. This is extremely important for the correct operation of the amplifier. I have modified the picture below and included the Zobel in red. Alex, can you please add this to the PCB? I apologize for the original omission, but it's absolutely necessary. The Zobel consists of 10R/3W resistor and 10nF (in parallel to) 47pF capacitors. Thanks for all of your great work.

EDIT: I just took a look at Alex's PCB again and saw that he is one step ahead and has already included the Zobel. Alex, can you please add a place for a second capacitor in parallel? This is a very wide bandwidth amplifier, it should have a 47pF capacitor in there 🙂

An externally hosted image should be here but it was not working when we last tested it.
 
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#120
NagysAudio said:
What I meant is that the schematic is tried and tested.
Click to expand...

it is when its been built
until then theres no 100% certainty
its a hand drawn schematic
is it copied from looking into a commercial amp, or ?
are there any amps built directly from your schematic ?
or do you rely on the schematic to be a 100% correct copy ?
you know, who came first, hen or egg
in this case it matters

would you like to share how you got this schematic ?

just an example
someone stuck a schematic in your hand and says, thats your amp
but you may not know if there have been small changes that may show on schematic
and so forth

please, its not to be negative in any way
if our skilled members say its interesting, then it is so
but more clarification would still be nice
 
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