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FdW

FdW

Member
Joined 2009
sq225917 said:
Quick question.

I'm building a set of pre regs that are outputting 37v under load (different transformers to cure the noise and they have slightly higher VA). Should I just slug the output of the pre-reg boards with a bigger resistor to drop the voltage. If so what's the optimum voltage?

I figure a 47r should slug me down to near 30v.

Your experience and thoughts please gents.I'll be adding Calvins to the amp boards that these run with if that affects the advice at all, currently the 37v is without Calvins in the middle of things.

Many thanks.
Click to expand...

Yes! :)
 
H

hesener

Member
Joined 2005
Paid Member
PierreQuiRoule said:
In the eventuality that my journey may be of use to someone else facing a similar challenge with their Paradise build, I will keep a record of progress in this thread. If it becomes off topic, please let me know.

So, the HFEs of the Fairchild and ON SEMI bipolars in the input stage differ at 4 mA Ic although they were well matched at 1 mA. Going through my bags of devices, the match really is never that great at 4 mA… So it is time to get some different devices, and aim for using the same brand in PNP and NPN positions.

The order includes:
  • KSA992FA and KSC1845F as substitutes for BC327 and BC337 (just for the input stage at 4 mA Ic, they would not do well elsewhere where Ic is 15 mA),
  • ON SEMI BC327-25, just to see if the -25 devices with the highest HFE will match my ON SEMI BC337-40, and
  • DIOTECs BC327-40 and BC337-40.

I wish I could find NXPs, for they were supposedly quite nice.

A question: Besides the input stage, where else does matching between PNPs and NPNs matters most? Q49 through Q52? What about Q22 and Q24?

Thank you - Pierre
Click to expand...

hi Pierre,

check the build guide, hfe matching between pnp and npn is recommended for the input stage, but apart from that matching is needed for each current mirror, so for each group of transistors (circles in the schematic). of course it helps when all transistors are more or less matched.

hope that helps, happy bricolage!
 
FdW

FdW

Member
Joined 2009
Bksabath said:
Yes and increased dissipation more heat in the box as suply is so close to active stages all sorth of things happens

You have seen mine whith extra finns to take heath off did U ?
Click to expand...

Yes, all true. And yes I did see the pictures. But he is going to add the larger valued resistors(on the pre-regulator, that was my understanding) to combat the overvoltage on the regulators, that will solve the(his) problem nicely.
 
RCruz

RCruz

Member
Joined 2006
Paid Member
Hello Frans

My latest Paradise sounds so good I do not dare to touch it "yet" but I have got some Calvin's boards with me and would like to use one of those to terminate Dadod's Gainwire.

The Gainwire is "also" a current conveyer thing and it does work quite well but I believe I should try this buffer "just for learning purposes... as usual"

This preamp works with +-15Vdc... can I use Calvin's buffer with this voltages without needing to modify any components values ?

Best
Ricardo

FdW said:
When using Calvin buffers in combination with the Paradise RIAA the preamp is going to need a bit more power than originally planned. The Paradise RIAA needs about 80mA and the Calvin buffer needs an additional 30mA.

For the shunt to function it needs to consume a few mA’s (30mA is the design value, actual values from 25 up to 50mA are acceptable). This results in 30ma x 18V = 540mW and 110mA x 8V = 880mW constant power consumption in the voltage regulator (Shunt, CVS and CCS), the total power supply consumption is:
2 x ((30mA 18V) + (110mA 8V (26Vin – 18Vout))) = 2.8Watt

When connecting the Calvin buffer an additional 30mA needs to be supplied, the CCS setting needs to be changed from 110mA to 140mA, this can be done by changing the 10 Ohm resistors to 7.5 Ohm resistors. See the attached JPG (The attached screen shows the CCS current in the PSU for (E24) resistors from 4.7 to 10 Ohm (currents from 240…105mA (give or take a few mA’s)).

The ‘normal’ power supply dissipation now changes to:
2 x ((30mA 18V) + (140mA 8V (26Vin – 18Vout))) = 3.4Watt

This should not be a problem with the supplied heat sink, but care should be taken to ventilate the area surrounding the PSU heat sink.

When testing the PSU (with the RIAA and buffer disconnected) the total power consumption in the PSU will be 140mA x 26V = 7.3Watt. If the PSU is not placed in a closed box this should not be a problem, the heat sink may get hot (up to 70C or so) and should not be touched (but you will know :) (as a regular soldering iron user)).

As ever, be sure that the final enclosure is well ventilated (especially around the PSU).

Regards,
Frans.

These are the most important/relevant messages regarding PSU and Pre-Reg.
  1. Mpp #4375 PSU-pre-regulator.
  2. Mpp #4610 V2 Schemas UPS and Amp.
  3. Mpp #6506 CCS fine-tuning.
  4. Mpp #6462 PSU with my notes.
  5. Mpp #6809 Do not try to feed the CVS of the CCS of the shunt with a regulated power supply.
  6. Mpp #7127 More about transformer selection.
  7. Mpp #7635 Single and dual transformer wiring (also corrected drawing) (See also #7733).
  8. Mpp #7733 Grounding (PSU, RIAA and Player).
  9. Mpp #7810 35V PSU for the CroMagnon.
  10. Mpp #7830 The PSU explained.
  11. Mpp #8386 My resistor recommendation’s.
  12. My Paradise #56 PSU Noise.
  13. Masterpiece #951 That's not a PSRR test (it's a CIR test) :)
  14. PradiseBuilders #13 Schema's and assembly guide.
  15. PradiseBuilders #155 Vdc input voltage minimum simulated.
  16. PradiseBuilders #970 PSU oscillates; posible solutions?
  17. PradiseBuilders #983 Compensating the PSU for oscillations.
  18. PradiseBuilders #1173 Fixing oscillations (up to #1182).
  19. PradiseBuilders #1322 Fuse :).
  20. PradiseBuilders #1387 Updated Paradise R3 assembly guide (Also German).
  21. PradiseBuilders #1403 Capacitors bad vs good.
  22. PradiseBuilders #1593 PSU Power Transistor selection.
  23. PradiseBuilders #1644 PSU Output Impedance.
  24. PradiseBuilders #1680 PSU Power Supply Suppression Ratio(PSSR).
  25. PradiseBuilders #1772 NJF selection for the PSU.
  26. PradiseBuilders #1887 Empirical NJF Rgs determination.
  27. PradiseBuilders #2127 More about the PSU fets (J113's etc).
  28. PradiseBuilders #2969 About the Paradise PSU using Calvin buffers.
Have a look at these and their following messages.
Click to expand...
 
Calvin

Calvin

Member
Joined 2004
calvins-audio-page.jimdo.com
Hi Ricardo,

You may use +-15V as supply for the Calvin buffer.
Besides less heat power loss the only difference to higher supply rails is a lower (soft) clipping limit.
15V should be good for roundabout 3-4Vrms of clean undistorted output voltage.
The cascoding JFETs are the limiting parts here.
After the rule of thumb, that the Vdg be at least 2x its Vgs the cascoding JFET chews up a couple of volts.
Due to the feedback action of the CFP more output voltage is possible, but distortion starts rising (appearance of higher harmonics on a still low overall niveau).
Hard clipping occurs either if the current limit is reached, or when the Vds over the cascoding JFET becomes too small.
This may occur for signals ~>7Vrms.
The limit depends of course also on the chosen JFET.

jauu
Calvin
 
FdW

FdW

Member
Joined 2009
RCruz said:
Hello Frans

My latest Paradise sounds so good I do not dare to touch it "yet" but I have got some Calvin's boards with me and would like to use one of those to terminate Dadod's Gainwire.

The Gainwire is "also" a current conveyer thing and it does work quite well but I believe I should try this buffer "just for learning purposes... as usual"

This preamp works with +-15Vdc... can I use Calvin's buffer with this voltages without needing to modify any components values ?

Best
Ricardo
Click to expand...

Hi Ricardo :) I see that Calvin already answered. Good to see that you are repeating this list of links.
 
RCruz

RCruz

Member
Joined 2006
Paid Member
Calvin said:
Hi Ricardo,

You may use +-15V as supply for the Calvin buffer.
Besides less heat power loss the only difference to higher supply rails is a lower (soft) clipping limit.
15V should be good for roundabout 3-4Vrms of clean undistorted output voltage.
The cascoding JFETs are the limiting parts here.
After the rule of thumb, that the Vdg be at least 2x its Vgs the cascoding JFET chews up a couple of volts.
Due to the feedback action of the CFP more output voltage is possible, but distortion starts rising (appearance of higher harmonics on a still low overall niveau).
Hard clipping occurs either if the current limit is reached, or when the Vds over the cascoding JFET becomes too small.
This may occur for signals ~>7Vrms.
The limit depends of course also on the chosen JFET.

jauu
Calvin
Click to expand...

Thank you Calvin

I believe 3-4Vrms is more than enough, but if I want more than 7vrms, what jfet would you suggest ?
 
A

amsoque

Member
Joined 2012
Hi,
I didn’t have the time to continue my research and I leave my Paradise for almost a year with his problems of hiss and hum, perhaps due to oscillations.
On the contrary, I found lately a strange behavior of my Paradise. If I disconnect the load resistor and leave the input floating or connected to the cartridge, the hum and hiss disappear completely, but instead the amplifier (?) becomes very sensitive, e.g. if I turn the knobs (volume, balance) of the amplifier they make a sound like if they were full of dust and dirty.
That last for a couple of minutes, after that one channel becomes noisy again with pretty loud hiss, the other remaining dead quiet with the same problem of high sensitivity.
Do you have any idea what happens? I get through all the thread looking for other oscillation issues.



Emil
 
H

hesener

Member
Joined 2005
Paid Member
Hi Emil,

(fortunately) this is an easy thing to fix. REmember the Paradise is DC coupled, and any DC offset at the input will be amplified and visible at the output. volume and balance controls made with potentiometers do not appreciate DC across them, causing a hissing sound when you turn them, and sometimes even if you don't.

Please check the assembly guide for adjusting the input offset, and always connect a load resistance to the input. The "native" input impedance of the Paradise is around 10kOhm, so a higher load resistance does not change things (a.k.a., forget MMs.... ) but something lower. I used 2200 Ohms and below with good results. (And, please note to connect them AFTER adjusting the input offset). Connecting a cartridge has the same effect on DC offset, by the way, only now the DC current is going through the cartridge - that may not be a good thing.

Of course you can always add an input capacitor to your line stage, but if it can be avoided, thats preferred.

Hum problem is IMHO always related to the cabling and in particular the grounding. In the build guide, there are some proposals, let me know if you can identify the issues, happy to help any time!

happy bastling
alfred
 
A

avi5720

Member
Joined 2012
I first thought in October 2013 that I have finished my build, just have to get nice boxes #3008 ... but when listening ... shock, where is this noise coming from :mad: ??? - the transformers :scratch1:
I contacted Benedetto, Benedetto contacted Block, Block answered Benedetto, Block send some transformers in exchange to Benedetto, I started changing transformers ... little improvement ...
Than a Group Buy in the german AAA Forum ...
PSU2_Paradise.jpg

again little improvement, but still noisy ... , so I ordered those:
Talema 55100-P1S2 Transformator:Ringkerntransformator;15VA;230VAC;12V;12V
since yesterday ...
PSU3_Paradise.jpg

I'm in Paradise :) the PSU is dead silent, I can lay back and enjoy listening ... cabling is not jet perfect, but ...
/torsten
 
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