Uhm, some development. HF oscillation under all conditions seems completely gone. Will try to find time and power both channels tomorrow but that's how it's looking atm. Infra low frequency breathing with some higher frequencies still modulated on output. In the absence of the HF noise it's now clear that the output not only "breathes" but there is some low frequency modulation too.
So, what happened? There has been some hf noise everywhere, even on the ground from day one. Not trusting the scope i didn't pay much attention until tonight. After running some tests it appears both polarities of the regulator contain some noise around 7-8MHz. Put together a quick 317/337 replacement and it appears all of this is now gone. It's getting late and i hope i am not wrong about this, but so far it looks that at least in my build it was the regulators oscillating.
The offset issue certainly remains.
So, what happened? There has been some hf noise everywhere, even on the ground from day one. Not trusting the scope i didn't pay much attention until tonight. After running some tests it appears both polarities of the regulator contain some noise around 7-8MHz. Put together a quick 317/337 replacement and it appears all of this is now gone. It's getting late and i hope i am not wrong about this, but so far it looks that at least in my build it was the regulators oscillating.
The offset issue certainly remains.
The simple answer for you is to just drop the whole thing. You said a week or so that you had so done - yet you eturn simply to criticise. Why? Do you have some thing better?
SEveral people have built this wel ad are enthused - I suggest that you go back and check it out. To decry the whole thing when you admit you gave up some time ago will not get you any sympathy.
I apologise for being rough - I have spent the afternoon at the funeral of a friend and his wife who were killed in a road crash.
SEveral people have built this wel ad are enthused - I suggest that you go back and check it out. To decry the whole thing when you admit you gave up some time ago will not get you any sympathy.
I apologise for being rough - I have spent the afternoon at the funeral of a friend and his wife who were killed in a road crash.
You are seriously mistaken if you think i am looking for sympathy. And true, i had not touched it until today. I guess i'm a bit inconsistent, or just felt bored. Sorry if this offends your sensibilities. Luckily, there is a very simple solution - do not read my posts.
I have to apologise for being so rough; I was today at a funeral for a good friend and his wife who were both killed in a dreadful road crash just before Christmas.
Perhaps you need to start at the beginning and simply work it through again having first re-read the major part of the thread. I am pretty sure that you may have made an error, or that a component or three may be inaccurately labeled. I have read some of your posts on other threads and know that you are skillful. Go back, check everything and then report here again. If several others have had no problems, then I suspect that there is something wrong in your build. Good luck!
Perhaps you need to start at the beginning and simply work it through again having first re-read the major part of the thread. I am pretty sure that you may have made an error, or that a component or three may be inaccurately labeled. I have read some of your posts on other threads and know that you are skillful. Go back, check everything and then report here again. If several others have had no problems, then I suspect that there is something wrong in your build. Good luck!
You know Joachim that some times it is lacking. Who would expect a massively expensive item such as this for the money it cost plus a chassis/case?
This, with a reworked Lenco, a decent carteride and arm, will outperform anything up to massive dollars/Euros/Pounds.
As you know I have been not too fit, but am now 100% again - for a deaf 70 year old! I have a great pair of your speakers: Thank you. Plus a lot of Be Yamamura cables, carbon bits etc. I am even now making two power amps [ the one you sent me, plus a Symsun TO-3 from Roender]. Also the buffer you sent with the FETs and - witin the next few weeks - will start on the Paradise - which is NOT ideal for my use, but a lot better than the 15 year old Ben Duncan MC stage I have been using with an Io.
I hope that I will be able to post some worthwhile comments soon.
In the meantime thank you, and your team, for all ou have done.
Have a great 2013 all of you!
You did not get the point. The servo is connected to the second opamp in case of MC version. That means it remains connected same as in a MM version. The output offset I measure in a MM version is below 0.5mV at several samples built. BTW, your math is completely wrong. For DC servo, you do not simply multiply Vos times gain. It is clear to me that you do not understand how the DC servo works. If there is a self-promoter, it is you and not me.
MC version was not made with transformer, but LT1028 connected in front of the MM version.
This is completely OT here, but YOU were accusing me for giving not schematics, promotion etc. If you want to know more, send me an e-mail. I am NOT going to continue with OT in this thread.
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For those interested in DC servos: DC servos compares output DC voltage with input DC voltage (usually ground) and sets voltage at the output of DC servo to drive the whole circuit to keep "zero" output voltage. In fact it is an integrator with time constant usually at something like 1s. The time constant of the whole circuit with servo also depends on resistor divider that is connected at the DC servo output.
DC servo can keep DC output voltage at the value close to Vos voltage of the servo opamp as long as voltage output of the DC servo opamp does not go to saturation. For the DC servo is an integrator, it may happen that the whole system's output DC would fluctuate, as it depends on behavior of the circuit that is inside the DC servo loop.
But, not that the output DC voltage of the whole system is DC servo input offset times DC gain inside the loop. This is NOT true.
DC servo can keep DC output voltage at the value close to Vos voltage of the servo opamp as long as voltage output of the DC servo opamp does not go to saturation. For the DC servo is an integrator, it may happen that the whole system's output DC would fluctuate, as it depends on behavior of the circuit that is inside the DC servo loop.
But, not that the output DC voltage of the whole system is DC servo input offset times DC gain inside the loop. This is NOT true.
No problem. My arm is wired balanced too, and in my pre-regulator I use only one power transformer (it then goes through two different bridges and cap multipliers), one ground connection. My ground loop is pretty large though. I found it pretty important to have the GND's come together only at the input (star) ground, and the pre-regulator ground should be connected only at the board input power connector only, so the ground is routed to the input through the board.
It was quite natural for me to do that, maybe I should have spent more time while betabuilding, deliberately setting up ground loops and check if the circuit still behaves
Interesting..... in the R1 betabuild, we had 4 boards where the regulators (CCS part) was oscillating , and stubbornly so. But these were built around LM317/337 CCS, cascaded with bipolars, and when Frans changed that to the discrete design for R3 that was all gone.....
You welcome
Actually I forgot to put smiley on previous post as picture is upside down
And maybe is worth looking at how the output cables to the Pre-amplifier are arranged
As the Pre amplifier is earthed trough the mains I may be worth cutting the screen at the preamplifier ends and that is why I just sqibled Out on those
By buss of star I mean
Star one all wire to the same point enclosure, board 1, board 2,maybe the ground cable from the arm, this then out to a single cable to the PSU or star 2 as follows: Cable to star 1, ground from pre reg 1,ground from pre reg 2, eart of enclosure and this out to the main plug.
Please note that there are no other earth connection to the cartridge as 4 independent wires are used and that same turntables, Like my RPM4 used to be before surgery, have the screens of the Phono cables connected to earth at the turntable end and this can cause a loop and maybe noise pick up (I say maybe as ground loops issues are a real pain in the bottom.)
Actually I forgot to put smiley on previous post as picture is upside down
And maybe is worth looking at how the output cables to the Pre-amplifier are arranged
As the Pre amplifier is earthed trough the mains I may be worth cutting the screen at the preamplifier ends and that is why I just sqibled Out on those
By buss of star I mean
Star one all wire to the same point enclosure, board 1, board 2,maybe the ground cable from the arm, this then out to a single cable to the PSU or star 2 as follows: Cable to star 1, ground from pre reg 1,ground from pre reg 2, eart of enclosure and this out to the main plug.
Please note that there are no other earth connection to the cartridge as 4 independent wires are used and that same turntables, Like my RPM4 used to be before surgery, have the screens of the Phono cables connected to earth at the turntable end and this can cause a loop and maybe noise pick up (I say maybe as ground loops issues are a real pain in the bottom.)
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Calm down, I guess I did. So, what you posted is a MM amp, not the MC amp you claimed here. Or similar, with a 20dB LT1028 opamp in front. Set aside this flies in your own face (by using a bipolar opamp in front, with the inherent bias current flying in the MC), any comparison with the Paradise falls flat.
BTW, there is much more than "can keep DC output voltage at the value close to Vos voltage of the servo opamp as long as voltage output of the DC servo opamp does not go to saturation" in a servo. I'll let you find out what's happening when the forward and reverse servo loop gains are comparable. BTW, you admit that "For the DC servo is an integrator, it may happen that the whole system's output DC would fluctuate, as it depends on behavior of the circuit that is inside the DC servo loop". At least that, it's a good starting point
.