HAYK...one could also consider the possibility that the sonic qualities of this particular chip (8932) have already been maximized in this circuit and there is nothing really left to draw out of it? Could it also be that the adjustments made with the ABD mod are so far up the frequency scale that most adults will never hear any improvement? I've made the assumption that your 200R resistor calculation was done according to known circuit adjustment calculations. My guess at a 10uF cap across the resistor was based on what would least change the final result of the two caps in the LC output filter. The wav file should be good to test with but I'll see if I have the Mozart piece in a flac format.
Pete
Pete
Well, I did this mod (just the resistor) as well.
I don't have the equipment to measure anything so I have to rely on my hearing to evaluate things. Now it's difficult to A/B anything because I only have one set of amps, but I believe I do notice some (admittedly slight) change.
To my ears the amp never exhibited any harshness or upper frequency glare, but with this mod I believe high frequencies are slightly cleaner and perhaps a bit more "round"- closely recorded violins strike me as more "palatable".
Please take what I have written in the light of my introductory statements - but so far, so good.
I don't have the equipment to measure anything so I have to rely on my hearing to evaluate things. Now it's difficult to A/B anything because I only have one set of amps, but I believe I do notice some (admittedly slight) change.
To my ears the amp never exhibited any harshness or upper frequency glare, but with this mod I believe high frequencies are slightly cleaner and perhaps a bit more "round"- closely recorded violins strike me as more "palatable".
Please take what I have written in the light of my introductory statements - but so far, so good.
Thanks dubai2000...I'm going to try the ACA power supply filter by rhthatcher between my single Mean Well LRS-150-24 PS and the amp boards to see if that adds anything. I'm using Richards shunts boards instead of the stock regulator called for in the schematic btw.
I did try Sparkos regulators (18V) in the U3 position and I did hear a bit of a musicality difference than with the shunt but not so much better that I would tell folks to spend the nearly $100USD although Shertzy did say that he thought the improvement was quite noticeable. I'm 66 so maybe my ears just can't detect the subtle changes in the upper frequencies.
Cheers, Pete
I did try Sparkos regulators (18V) in the U3 position and I did hear a bit of a musicality difference than with the shunt but not so much better that I would tell folks to spend the nearly $100USD although Shertzy did say that he thought the improvement was quite noticeable. I'm 66 so maybe my ears just can't detect the subtle changes in the upper frequencies.
Cheers, Pete
Richard... In chatting with him in PMs I believe he said something like he tried your discrete regs (I'm assuming shunts) but they made the music less enjoyable than with stock regs while the Sparkos regs greatly improved sonics. But you obviously would know if he bought them or not, right?
Maybe he can chime in.
Cheers, Pete
Maybe he can chime in.
Cheers, Pete
Speaking of improvements to higher freqs, I now have a prototype which does sound a bit clearer than monoAMP. Trouble is, its way too 'hair shirt' to turn into a kit at present. There are 12 * AD815 ADSL drivers soldered to this double-sided PCB, 6 in parallel per channel....
The nice thing about having the power rails on either side of a DS PCB is - its very easy to go crazy on adding caps around the edge.
The nice thing about having the power rails on either side of a DS PCB is - its very easy to go crazy on adding caps around the edge.
Its going to need a fair amount of work to make it a practical solution. At present the issue is - it runs too hot. The AD815s are too close together so I'm starting on another build with just one channel (rather than two as here) on the same size sheet of PCB. We'll see how that goes. The version in the picture can't run anywhere near the max supply for the chips due to overheating, and that's not even playing music, just the quiescent current which rises as the temperature increases. So a kind of thermal runaway.
I've used them as well but only for preamp projects that draw less than 1A.
My recollection from building them was they really cant be used above 1A which I why I went to the ACA smps filter which can handle much more current.
Pete