My amp design schematic

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#21
sam9 said:
Doing some mental gymnastics to untangle the spagetti it appears to me a highly generic amplifier with symetric topology. It looks like it came out of a textbook.
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No, not out of a textbook. It is simple, simple is good. Not trying to reinvent the wheel(or amp) here, just make a simple usable design that people can play with and make the way they want to.
 
#22
Markp,
What is this? I am in agreement with all the critics here and then some. I am not sure what the purpose of this thread is, besides a mild case of trolling.
I think we all got better things to do than reinterpreting your bizarre looking schematic and/or hearing your claims of great sound. Quite clearly people are genuinly interested in your circuit so, if your purpose is to teach electronics I would just stop hinting that everyone's an idiot, admit that you posted a F'd up schematic and then start giving a detailed explanation of your circuit and the reasons why it may be different/better than anything else out there.
 
#23
markp,
r u influenced by Bush? Bur we r not saddams. U r attacking us as u want. We r all friends here. try to be like a friend. If u can't draw proper schematics it is ur fault. improper drawing is not learning. First learn urself then teach others.
 
#24
palesha said:
markp,
r u influenced by Bush? Bur we r not saddams. U r attacking us as u want. We r all friends here. try to be like a friend. If u can't draw proper schematics it is ur fault. improper drawing is not learning. First learn urself then teach others.
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Palesha, LOL, but while I catch your implicit 'drift', ascribing political views to what is more properly viewed as the vagaries of personality will do little to cure Mr. Pindler of his shyness.
And you're gonna tick off a bunch of us cowboy Americans....:smash:

Nor is the schematic 'improper', it is simply not what we generally expect, albeit, the resolution really sucks. But if I can discern its topology, I'll assume that many (most?) can do likewise. But I wonder whether Markp has actually built the amp as he seems unwilling to answer my naive technical questions, or if the board's cynicism has him totally discombobulated....
 
#26
Any of those that live in Los Angeles are welcome to come on over and see and hear the amp. It's funny how all of you are willing to bag on a schematic with poor resolution! Well, all of you are missing out on the idea of taking the circuit and actually trying it out(of course you must know how to calculate all the values not listed). The invite is open...
 
#27
palesha said:
markp,
r u influenced by Bush? Bur we r not saddams. U r attacking us as u want. We r all friends here. try to be like a friend. If u can't draw proper schematics it is ur fault. improper drawing is not learning. First learn urself then teach others.
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You must be kidding! What kind of response is this but an attack?
 
#29
Re: Re: My amp design schematic

pmkap said:


How very kind and altruistic.:irked:

A lovely and visually symmetrical schematic. Complementry LTPs fed by CCSs to complementry Vas(s) with a amplified diode Vbe betwixt and between to emmitter folowers.

So how do you adjust output offset? Are the non-inverting complementry LTPs base currents so well matched that you don't need a input cap? No drivers that I can see, so how many of those "multiple ouput pairs" can you drive as is? (I can't discern the ouput trans, are they Darlingtons?)
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The offset is less than 10mv on the worst example I've made.
No input cap is needed as the base currents are very evenly matched in the dual devices used.
Up to four pairs of outputs can be driven by the drivers with no problems. They are not darlingtons.
 
#30
pmkap said:
But I wonder whether Markp has actually built the amp as he seems unwilling to answer my naive technical questions, or if the board's cynicism has him totally discombobulated....
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You answer your own question in a previous post.

Personally it seems to me it MIGHT be that he didn't want to take the effort to draw the schematic in a more sensible way and include some (even ballpark) values, not expecting to receive such criticism for it.

If you want people to learn, why make it a translation process first? If you want people to think your amp is great, give values so it can be built. It seems to me that a LOT of unique designs are prototyped for evaluation by the members here...

or wait... are you just scared to have someone build it just like you did and have them say it stinks?
 
#32
Stocker said:


You answer your own question in a previous post.

Personally it seems to me it MIGHT be that he didn't want to take the effort to draw the schematic in a more sensible way and include some (even ballpark) values, not expecting to receive such criticism for it.

If you want people to learn, why make it a translation process first? If you want people to think your amp is great, give values so it can be built. It seems to me that a LOT of unique designs are prototyped for evaluation by the members here...

or wait... are you just scared to have someone build it just like you did and have them say it stinks?
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As I said, come on over and see and hear the amp. Your right on one count, I thought people would actually try to figure it out, kind of like a project. Instead they chose to make comments about a bad drawing, too bad. With all the brains here I thought one of them would be willing to do the math.
 
#33
pmkap said:
Mark,
Thanks for the response. As you obviously meant to apprise the board of the semiconductor's part#, but the resolution.....

Would you please let us know the semi part #s so we can look at their parameters?
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Inputs are 2SA1349 and 2SC3381.
Drivers are 2SA968A and 2SC2238A although I've used a few others.
Outputs are MJL21193/4, I've yet to try newer ones but I'm sure they can be used.
 
#35
Elso,

Thanks for the kewl link! Indeed, very similar, save for Mark's circuit lacking an EF driver [what others are calling 'drivers' still look like complementry Vas(s) to me]. But the major difference, IMO, is the simplicity, actually the lack of adjustment capability. Not being able to discern the semi specs is what prompted my original questions as to the lack of inputs cap and output offset adjustment. Now, I'm assuming that those rather difficult to source 1349/3381s would also have to matched rather closely for gain (Hfe?) Or do those non adjustable CCSs keep everything simpatico? To a lesser extent, I also assume the same applies for the 968/2238 complementry Vas(s).

But Mark's schematic really is very appealing. While the requisite matching might well preclude its use as a production amp, to the DIY/Bespoke builder, it simply adds to the cachet.



Mark,

If you're going to go all Socratic upside our heads, you've really got to give us a bit more to work with. If you expect my betters to calculate the diff pair degeneration values, wouldn't we need to know the gains of the LTP and Vas transistors, as well as the taget net gain (26db?), as this local feedback is implicitly going to change the OLG of the circiut? I'll apologize in advance if these are stupid questions due to my lack of understanding.....

PS - What are you setting the bias to on a single output pair configuration? Is this design for Class A, A/AB, 'blameless' or is it universal?
 
#36
pmkap said:
Elso,

Thanks for the kewl link! Indeed, very similar, save for Mark's circuit lacking an EF driver [what others are calling 'drivers' still look like complementry Vas(s) to me]. But the major difference, IMO, is the simplicity, actually the lack of adjustment capability. Not being able to discern the semi specs is what prompted my original questions as to the lack of inputs cap and output offset adjustment. Now, I'm assuming that those rather difficult to source 1349/3381s would also have to matched rather closely for gain (Hfe?) Or do those non adjustable CCSs keep everything simpatico? To a lesser extent, I also assume the same applies for the 968/2238 complementry Vas(s).

But Mark's schematic really is very appealing. While the requisite matching might well preclude its use as a production amp, to the DIY/Bespoke builder, it simply adds to the cachet.



Mark,

If you're going to go all Socratic upside our heads, you've really got to give us a bit more to work with. If you expect my betters to calculate the diff pair degeneration values, wouldn't we need to know the gains of the LTP and Vas transistors, as well as the taget net gain (26db?), as this local feedback is implicitly going to change the OLG of the circiut? I'll apologize in advance if these are stupid questions due to my lack of understanding.....

PS - What are you setting the bias to on a single output pair configuration? Is this design for Class A, A/AB, 'blameless' or is it universal?
Click to expand...
Those duals are not that hard to find, are they? MCM even has them for about $3 each. They are very closely matched for Hfe and if you wish you could use a balance pot instead of fixed values on the diff emitters. I try to keep the values to around 200 ohms to get the stability without loss of a lot of gain.

Bias can be anywhere from just above the switching level to above 100ma but it sound much better on the higher end of the scale(around 100ma).
 
#39
markp said:
...MCM even has them ....They are very closely matched for Hfe and if you wish you could use a balance pot instead of fixed values on the diff emitters. I try to keep the values to around 200 ohms to get the stability without loss of a lot of gain.
Click to expand...

Thanks for the MCM reference. But I obviously didn't ask my questions clearly. I'm not questioning the inherent matching of the characteristics of transistors in the duals themselves, but rather, if the lack of input cap and adjustable offset capability was dependent of characteristic matching between the complemetry 'equivalents'.

As MCM doesn't specifiy the grouping of the transistors, I might well get a 'BL' 3381 and a 'GR' 1349. Are you telling me that your schematic, as shown, will not require an input cap or offset adjustment in such a circumstance?
 
#40
pmkap said:


Thanks for the MCM reference. But I obviously didn't ask my questions clearly. I'm not questioning the inherent matching of the characteristics of transistors in the duals themselves, but rather, if the lack of input cap and adjustable offset capability was dependent of characteristic matching between the complemetry 'equivalents'.

As MCM doesn't specifiy the grouping of the transistors, I might well get a 'BL' 3381 and a 'GR' 1349. Are you telling me that your schematic, as shown, will not require an input cap or offset adjustment in such a circumstance?
Click to expand...
I've always received the same characteristic group for both pnp and npn but if you don't then you would use a trim pot to balance the offset.
 
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