Yes, the Paradise is made for MC cartridges and not for MM cartridges.
Ricardo, i do put a cap parallel to the input some times.
It is not entirely clear at this moment if high hfe BJTs anywhere in the circuit provokes oscillation. There are Paradise builds out there that do not have that problem although high hfe BJTs are used.
Ricardo, i do put a cap parallel to the input some times.
It is not entirely clear at this moment if high hfe BJTs anywhere in the circuit provokes oscillation. There are Paradise builds out there that do not have that problem although high hfe BJTs are used.
The paradise has huge amounts of local feedback, and that may create local instabilities. Because of the high beta of the input devices, combined with the huge transconductance, the input stage is in particular prone to such. An input cap will kill an important regenerative path.
Simon is quite right of course now for same more details.
Build a little power supply with a LM317 set the voltage to the nominal capacitor voltage and connect all the capacitors to it.
Let the capacitors stay there for a while (1 or 2 days) and this will form the capacitors.
Once the capacitors are charged they will use very little current so you can plug in as many as you like with no problems.
No need for any fancy stuff a litle breadboard is plenty
If you don't have a breadboard this is a link for it
WB-DJ - WISHER - BREAD BOARD, WB-DJ | Farnell United Kingdom
Attachments
No idea how you came up with the 2kohm fantasy. I had clearly stated that so far i have only experimented with a Denon 103 mainly due to its expendability. It may not be ideal for the purpose but noise levels are just not acceptable.
Hence my suspicion for oscillations. Or i have an unusually noisy batch of transistors. My scope is quite old and useless 60MHz unit. Hope to have a 200MHz within a month and then will have another look at the output.
Appreciate your kind offer and absolutely no need to cover cost of shipping. I was just hoping that someone in your more immediate neighbourhood may have similar symptoms but apparently not many feel the rush to finish this project
Lets give it another week or so... Again, appreciated.
Dear anolog_sa
sorry dude but I do not care much for your attitude in post 865
You are now with PMA on my ignore list.
I like this tread quite a lot and is better if is free from primadonnas
Post as much crap as you wish (I do ) but keep this constructive please
Most like me are just learning (my first BJT build of this size)
Have a look at post 867 is well worth the effort.
Altrought I don't have pearl II but that is most certanly in my list of things to build.
Maybe just another Pear and Orranges thing....
sorry dude but I do not care much for your attitude in post 865
You are now with PMA on my ignore list.
I like this tread quite a lot and is better if is free from primadonnas
Post as much crap as you wish (I do ) but keep this constructive please
Most like me are just learning (my first BJT build of this size)
Have a look at post 867 is well worth the effort.
Altrought I don't have pearl II but that is most certanly in my list of things to build.
Maybe just another Pear and Orranges thing....
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Already wrote it. I also use a DL 103 and at the first try i have big problems with noise. It was a ground problem, could controll it with seperate psu for both boards. Ground of the turntabe connect to ground of one board.
Now, no hum, no noise!
@Alfred
right choise ;-)
Chris
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Would it be posible for you to try the single transformer PSU as mentioned/shown in
Mpp #7635 Single and dual transformer wiring (also corrected drawing) (See also #7733).
Mpp #7733 Grounding (PSU, RIAA and Player).
@Bksabath,
The problem re. Analog SA's post is that he did mention a "2K" cartridge, but he was probably then refering to cost and not to resistance.
What surprises me is that a short time ago he announced that he is abandoning this project rather than seeing it through to the end; yet he now makes critical comment - albeit from an "academic" stance. Yet others have made the Paradise work - and with success.
It would be better if we were to attempt to sort the problems quietly rather than rush to find fault with the underlying design concept.
The problem re. Analog SA's post is that he did mention a "2K" cartridge, but he was probably then refering to cost and not to resistance.
What surprises me is that a short time ago he announced that he is abandoning this project rather than seeing it through to the end; yet he now makes critical comment - albeit from an "academic" stance. Yet others have made the Paradise work - and with success.
It would be better if we were to attempt to sort the problems quietly rather than rush to find fault with the underlying design concept.
The context of 2k is obvious to all but the most casual reader. It's not even worth discussing.
The critical comment about the input offset has nothing to do with all the output offset and oscillation issues. It is more one of usability and safety.
Do you honestly think that for a user with several cartridges such a concept would really work? Every time you want to change a cartridge you remove the lid, plug in a dummy cart resistor and adjust input for zero. Nah, this cart doesn't sound this hot - repeat procedure and you're done. And you will never forget which was the last cartridge you set it for? Sooner or later something will get magnetized. I know there are demaggers, i think Cardas used to sell one, but in all honesty i don't know how well these devices work.
In any case, as i said, these are usability issues and have nothing at all to do with the twitchy offset and possible oscillation. If one owns a single cartridge and never lends equipment to friends, it's a moot point.
Grounding....
Hi all,
just a small thing I remember now - when I was testing the R1 boards, I noticed that when both boards were placed (via isolation, of course) on top of the same ground plane, and one board was oscillating, the other board picked it up quite easily..... All my further builds were using the "two bathtubs" method that is outlined in the assembly guide.
In my opinion, definitely the way to go
just my two cents......
Hi all,
just a small thing I remember now - when I was testing the R1 boards, I noticed that when both boards were placed (via isolation, of course) on top of the same ground plane, and one board was oscillating, the other board picked it up quite easily..... All my further builds were using the "two bathtubs" method that is outlined in the assembly guide.
In my opinion, definitely the way to go
just my two cents......
I am sure that if once the 200 and so builds are done and issues if any came up Joachim and crew will do their very best to make the paradise even better, no matter how much time this will take.
Just because one of 2 rotten apples we risk loosing this support and making something really exceptional.
Yes I remember now he giving up one more reason for me to ignore his contribution.
It saddens me that the very important issues get burried under so much dross.
Let's all take a deep breath, relax, and get back to Paradise mood.....
What analog_sa brings up does make sense, however, once a loading resistor is connected to the input, and the offset is adjusted (and probably settled) (please note if the input stage transistors are matched for hfe, the remaining offset will be very very small), no further adjustments are likely to be needed. I am running the paradise R2 without input offset adjustment, and cannot measure any DC at the input.
Many (DIY and professional) MC phono pre's are on the market, with DC coupled inputs, and this seems to be a non-issue. In fact, I asked that question over at John Curl's "Blowtorch" thread, and the experts commented that they never saw this as an issue (PMA you may remember as you were one of the experts replying to this).
I saw your circuit before, but the ground of both boards are common, only the ground of the turntable is decouples through DDRC, right?
If so, I don´t thing it solve my problem, because my first try are without grounding the turntable. Missing ground of the turntable produce only hum, but no noise like both pluged connectors of the cart.
I thing the problem is the common ground of the boards in combination with grounding the input.
Chris
I am much more intrigued by another comment made (sorry I forget whose idea that was):
Could it be that big elcaps exhibit low-frequency "1/f" noise? This would get amplified with the low frequency amplification (80dB or so), and the servo has not much effect at 1Hz and above..... Could this be the source of the output fluctuation that we see? In fact, if thats the case, it would be even worse with JFET inputs (in the same circuit, that is - they may not require the elcaps at alll)
thoughts?
Could it be that big elcaps exhibit low-frequency "1/f" noise? This would get amplified with the low frequency amplification (80dB or so), and the servo has not much effect at 1Hz and above..... Could this be the source of the output fluctuation that we see? In fact, if thats the case, it would be even worse with JFET inputs (in the same circuit, that is - they may not require the elcaps at alll)
thoughts?