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Old 15th January 2018, 03:56 PM   #10931
avinunca is offline avinunca  Europe
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Help sought - My Paradise shunt regs are using 40mA more on the positive rail than on the negative rail. I bought a completed Paradise phono minus prereg as a stop gap until I could build my own.
So with +/- 26V I see 145mA on negative rail and 185 mA on positive. The Calvin buffer is disconnected. I can adjust for 18V on both outputs. Pics of one board here
Michael Lakeman | Flickr The amp works and sounds good to me. Maybe it could sound better though.
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Old 15th January 2018, 04:08 PM   #10932
hesener is offline hesener  Germany
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Check the 10 Ohm resistors (R104, R204) for their values. While not ideal, this difference is not alarming. Is it the same behaviour on both channels? And, do you have a scope where you can check if one of the regulators is oscillating?

If that doesnt work , the regulator schematic has typical voltage levels noted, you may want to check those.

By the way, there is a paradise builders thread here: Paradise Builders

where you may want to ask those questions, maybe better than in this MPP thread....
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Old 15th January 2018, 04:13 PM   #10933
avinunca is offline avinunca  Europe
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Thanks Hesener. Sorry I posted in wrong thread. It's same both channels. Will check resistors and for oscillation.
Michael
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Old 15th January 2018, 10:07 PM   #10934
Onvinyl is offline Onvinyl
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Quote:
Originally Posted by Joachim Gerhard View Post
I can say one thing : there is no superiour topology. It is all in the details and execusion.
And that comes from a man who has build any thinkable topo, at least quite a lot! If you think about it, it would be very strange if there were such thing as a single best topology.
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Old 15th January 2018, 10:12 PM   #10935
Onvinyl is offline Onvinyl
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Originally Posted by RCruz View Post
I like the Pearl phono.... very good design.... maybe it could be improved with a good psu.

I am sure the psu is an integral part of any amp because it sings along with it.

I use a pair of jfets in the input of my phonostage... and it is quiet.
Hi RC,
Which circuit are you using? I often experienced (well, three different topos or so...), that a single fet sounds better than paralleld fets if it werent for the noise penalty.
Rüdiger
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Old 15th January 2018, 10:23 PM   #10936
Joachim Gerhard is offline Joachim Gerhard  Germany
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So the most simple circuit that does the job is the best. Theoretical. Occam´s Razor.
Anyway, with vinyl it is also about taste in sound so reaching the goal in a particular system is not that easy any more. Is is about beautiness in sound ? Then it get´s real difficult. So what is the job ?
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Old 20th May 2018, 10:49 AM   #10937
RCruz is offline RCruz  Switzerland
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Hello Joachim

Still trying to understand the paradise schematic and need your input.

There are two voltage references that provide VCASCH and VCASCL.

The are made with a ccs and a zener in each case.

R11 Q97 D2 and R10 Q98 D1

What is the purpose of such a circuit ? In my simulations the circuit works perfectly without these subcircuits......

BTW.... Good sound in the MOC this year.... love your speakers

Ricardo
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Old 20th May 2018, 10:51 AM   #10938
RCruz is offline RCruz  Switzerland
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better sch
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File Type: pdf Paradise R3 schematic amplifier annotated (1).pdf (21.3 KB, 55 views)
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Old 20th May 2018, 05:06 PM   #10939
Calvin is offline Calvin  Germany
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Hi,

I guess D1 and D2 are just used to drop voltage so that the JFETs don't suffer from high Vds and heat losses.

jauu
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Old 20th May 2018, 06:33 PM   #10940
sq225917 is offline sq225917  United Kingdom
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They do nothing. They are a hangover from a previous incarnation of the circuit and they were just never removed from the schematic as the circuit was improved. (I think one of the team secretly had shares in 2sk170s ;-)

Click the image to open in full size.
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