Paradise Builders

[FdW]

Originally Posted by Take5

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

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).

[RCruz]

Originally Posted by analog_sa

If i put the wrong wand in the arm a 2k cart may prematurely go to Paradise. It is an accident waiting to happen and sooner or later it will.

Originally Posted by analog_sa

No idea how you came up with the 2kohm fantasy.

[brianco]

@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.

[analog_sa]

Originally Posted by brianco

@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 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.

[hesener]

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......

[Benedetto]

@analog sa:
RTFM !
If you manage to do so, you'll see what Alfred did to solve
your "Issue" .

[Bksabath]

Originally Posted by brianco

@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.

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.

[hesener]

Originally Posted by Benedetto

.....

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).

[Take5]

Originally Posted by FdW

Would it be posible for you to try the single transformer PSU as mentioned/shown in

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

[hesener]

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?