now that is a problem..
So, could You reassume, please, the present situation:
card 1.) R11 repaired? result?
card 2.) 1,6V on pin 6? 0V on output?
question: You are aware of the fact that I asked for Not Out_Gnd (the Faston pin at the relay) but PGND pin between the main reservoir caps?
So there is really 0V between this PGND Faston and Output Faston connectors?
Anyway, just wishing more luck..
George
So, could You reassume, please, the present situation:
card 1.) R11 repaired? result?
card 2.) 1,6V on pin 6? 0V on output?
question: You are aware of the fact that I asked for Not Out_Gnd (the Faston pin at the relay) but PGND pin between the main reservoir caps?
So there is really 0V between this PGND Faston and Output Faston connectors?
Anyway, just wishing more luck..
George
no life after new R11.. eeh, not the best news. Means that one of the chips - or both- had suffered, unfortunately. You can always try with the LM318 first, hopefully you have some extra, or available..
Otherwise.. two days ago I had seen some LM3886 popping up at RS .. and not the first time. But no warnings, and they are gone in a very short time.
But maybe, with luck and time it could be caught?
Otherwise.. two days ago I had seen some LM3886 popping up at RS .. and not the first time. But no warnings, and they are gone in a very short time.
But maybe, with luck and time it could be caught?
Sorry for the late response, not much time when you have 2 jobs, ok I got 0v on pin 6 but PGND faston to output faston was 14.2 v , again all voltages on board good
Thanks for the measurement on the relay control. Though I have to retract what I guessed: given that the "0V output" measurement was not at the right place, and given that you see 14,2V on the real output, I would just confirm that the relay circuit is just working: it opens when excess DC is present on the output..
Now I suppose You see this 14,2V on the board with replaced R11, after the contact accident?
If yes, than unfortunately all indications show a failed LM3886 chip, and possibly LM318 too.. (if there is 14,2V on the output, and by design 0V DC on the LM318 input, well then the LM318 output pin (pin 6) can not regularly stay at 0V..)
In the same way, if the current pump sees 0V at it's input, in no regular way it could stay at 14,2V at output..
(by the way, that 14,2V is suspiciously equivalent of the regulators output..hmm)
In my experience, all these factors together: the extraordinary event, accident of touching at an unfortunate, sensitive point; the resulting blow of R11; and now the grossly off voltages at key points are all indicating failed chips..
So at least for this channel I would warmly suggest a replacement of both..
You had spent a lot of effort & money, a very nice setup - hope this hickup will not block You from enjoying it..
Now I suppose You see this 14,2V on the board with replaced R11, after the contact accident?
If yes, than unfortunately all indications show a failed LM3886 chip, and possibly LM318 too.. (if there is 14,2V on the output, and by design 0V DC on the LM318 input, well then the LM318 output pin (pin 6) can not regularly stay at 0V..)
In the same way, if the current pump sees 0V at it's input, in no regular way it could stay at 14,2V at output..
(by the way, that 14,2V is suspiciously equivalent of the regulators output..hmm)
In my experience, all these factors together: the extraordinary event, accident of touching at an unfortunate, sensitive point; the resulting blow of R11; and now the grossly off voltages at key points are all indicating failed chips..
So at least for this channel I would warmly suggest a replacement of both..
You had spent a lot of effort & money, a very nice setup - hope this hickup will not block You from enjoying it..
The feedback loop (C9) is giving a -3dB response around 1,9Hz, the input decoupling -3dB point is around 1,5Hz.
These two together, because of the closeness in the responses are forming a second order highpass filter with -3dB at around 2,6Hz, and a 40dB/ decade slope.
That means the gain of the amp is down from ~+30dB nominal output to -10dB signal level at around 0,17Hz..
That is 40dB, 100 times less signal.
These two together, because of the closeness in the responses are forming a second order highpass filter with -3dB at around 2,6Hz, and a 40dB/ decade slope.
That means the gain of the amp is down from ~+30dB nominal output to -10dB signal level at around 0,17Hz..
That is 40dB, 100 times less signal.
Well I've finally gotten around to implementing the buffer resistor mod, and am enjoying the results. As already reported, it removes an edge from the sound and I find myself listening comfortably at higher volumes - very nice! Definitely worthwhile for anyone who still has the urge to tweak. Thank-you George.
Dario, with all respect to George, I did the resistor mod with my ADA4627-based build and although it did add a smoothing effect it did take away from the sparkle at the upper end. I don't reach even moderate levels of loudness with my setup and I don't experience any harshness in the upper end right now so I took the resistor back out. I have not tried the resistor mod with my 828 version of the amp as it's beautiful sounding as is. Don't know whether you can fit in a jumper to allow a 1K "in vs out" setting. The current Fremen Evo A (I have V1.7s) is a beautiful sounding amp with the audiophile build components installed. It could be the 1K is not optimal for the 4627 opamp.
We'll wait for George's opinion.....
Cheers, Pete
We'll wait for George's opinion.....
Cheers, Pete
Just wanted to GB the board, any suggestion on version for newbie?
I found the Evo A Mod is measured by Tom from neurochrome which performance is onpair with Modulu-86.
Because I don't know the parts price of Modulu-86, but the price of My_ref FE is probably lower?
Apart from the price, I have 2 transformer on hand, 1 for 280VA +/-26V and the another is 200VA +/-24V, I'm curious if I can use then per channel?
I found the Evo A Mod is measured by Tom from neurochrome which performance is onpair with Modulu-86.
Because I don't know the parts price of Modulu-86, but the price of My_ref FE is probably lower?
Apart from the price, I have 2 transformer on hand, 1 for 280VA +/-26V and the another is 200VA +/-24V, I'm curious if I can use then per channel?