You can find rather complete information about the bridged amp here :
http://www.diyaudio.com/forums/analogue-source/195017-jg-s-nobrainer-nobrainer-discrete-4.html
http://www.diyaudio.com/forums/analogue-source/195017-jg-s-nobrainer-nobrainer-discrete-4.html
I was wondering that too.
Hello, as a silent LA reader I am kind of new to the party.
Anyway, Mr. Putzeys article was very inspiring; really love it ! It has already generated further ideas.
Right now I have no need to build this pre-amp because I did a design based on the Bill Whitlock circuit the article refers to. But instead of the THAT chip I used a quad LM4562 (LME49740). I think it really works great from what I have measured so far (>= 100dB CMRR between 50Hz and 1KHz). I did not do a "source imbalance immunity" test yet, though. Too lazy and busy with speakers.
But maybe I can use the new knowledge to improve my pre-amp later.
Yet, I was wondering about the component tolerances of Mr. Putzeys circuit. Wouldn't the low pass section compromise the CMRR of the diff amp ? Or is it simply presumed to buy a bulk of each passive component in that area of the circuit and match them ? Or is it a non-issue that my hobbyist eyes don't see ?
Just send me an email with your question/suggestion and I will forward it to Bruno and consider it for online posting.
jan
Joachim I just realized you probably need a balanced signal for that. Bruno's design is balanced impedance but not balanced signal wrt ground.
jan
I talked to Bruno today. Actually i will not finish this design until Frickelfest.
Some pads have lifted off due to my lesser abilities to stuff tiny SMD:
So i will use a Lundahl transformer now.
I may have talked Bruno into making stuffed boards though.
I think he will contact you about this.
Would be nice if that can be made available over Linear Audio.
Of cause this is not my decision but yours.
Some pads have lifted off due to my lesser abilities to stuff tiny SMD:
So i will use a Lundahl transformer now.
I may have talked Bruno into making stuffed boards though.
I think he will contact you about this.
Would be nice if that can be made available over Linear Audio.
Of cause this is not my decision but yours.
Ahh, good - thanks John. I don't feel so alone now.
A pcb layout?
The number of ICs are 'new territory' and the signal electrolytics caps are quite foreign, despite the page 162 explanation - perhaps film caps could be subbed for the smaller ones, but not sure about the larger ones - bipolar? anti-parallel?
I wonder if a 'Cross Feed' cct for headphone amps could be included somehow?
A pcb layout?
The number of ICs are 'new territory' and the signal electrolytics caps are quite foreign, despite the page 162 explanation - perhaps film caps could be subbed for the smaller ones, but not sure about the larger ones - bipolar? anti-parallel?
I wonder if a 'Cross Feed' cct for headphone amps could be included somehow?
Sadly the PCB is now unobtanium. The bootstrapped '95 one with AD797 I am on about. The newer design with AD825 and floating pre-reg was a complete waste of space.
PS. I am not criticising the PCB layout of the newer versions or ALW's PCB layout etc. In many cases this this was probably better.
Their was just something better about the original. Like a good aged whisky.....
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I layed out the original, when I was still tender, and didn't have the acres of layout under my belt I have now. Looking back on it I don't feel it looks particularly 'nice' (will never make a glossy product picture) but it did work quite well.
Maybe I should do a reprise?
jan
Dear Jan,
I really think you should, but remember you need to allow provision for T-O3P, TO-264 and such like for people with larger members in mind!
Remember, it is going to take 100 Farad at least of the finest quality high ripple capacitors available, possibly up to 1000 Farads of this capacitance to remotely equal the performance of these regulators with respect to feeding the output stage of a power amplifier.
Let us not even get into remote sensing and fully balanced amps just yet....oh and forget the Wurcer cap mod with the AD797 whilst your at it....
Load protection is another issue that needs discussed when output transistors short circuit. VI is not that good esp. with mosfets.
Will be in touch
Kevin
Kevin, no offense, but I don't have the time nor ambition to embark on a one size fits all project - I've seen too many projects get grounded here after a lot of effort and endless discussion whether the cap should be red or green.
My offer was for a new layout of the 1995 superreg.
But don't let me hold you back
jan
My offer was for a new layout of the 1995 superreg.
But don't let me hold you back
jan
I remember looking into it and thinking you guys were pretty close to the max output. I do believe it was related to the opamp limits. I was hoping to get to the 36V region. I have contacted peranders about his sjolstrom regulator. It is also limited as far as higher voltages are concerned. Thanks for the time and suggestion.