Pumpkin preamp - More Boring Making Thread

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#401
Zen Mod said:



ask sp300b , even if he'll probably change his nick these dayzzzzz in spbabelfishj
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He, he, he - You're terrible right Zen 😀 - I have to change nick. babel really has deserved it. And once Pumpkin completed then again change to sppumpkin 😉
 

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#404
Re: regarding socks and sockets 😉

Zen Mod said:
AR2 sent me few files these days .....

little Pumpie & Shunty test
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I have finally finished Shuntys and I was very pleased with improvement it made over my previous power supply. What is the most apparent is how low is the noise floor. On the measurement it shows aprox. -93dB! It is rare to see that level with analogue equipment. This is the measurement normally reserved for the digital stuff. Shunty is very complex power supply but it is well justified based on the results. :worship: to the master.


:cheers:
 
#406
Re: Re: regarding socks and sockets 😉

AR2 said:



I have finally finished Shuntys and I was very pleased with improvement it made over my previous power supply. What is the most apparent is how low is the noise floor. On the measurement it shows aprox. -93dB! It is rare to see that level with analogue equipment. This is the measurement normally reserved for the digital stuff. Shunty is very complex power supply but it is well justified based on the results. :worship: to the master.


:cheers:
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hehe

Shunty is probably less complex than TL072 , but I can bet that I can make it singbetter than 072 😉

anyway - let us know your impression - what's difference in sound between shared (between channels) generic PS and this one ..... "complex" 😉

😉

btw - as I said before - Masao Noro's shunt reg is example of elegance ; Shunty is .......... Shunty .
 
#407
Hi ZM,

I powered up the shunty without the fuses but still blew out the R21 & R22 on both channels. Are you sure they can be rated mere .25W as stated in the cook book. I should have checked it earlier at .25W the max current they can take is only about 200 ma. Actually I used the digikey id PPC4.7BCT-ND - RES 4.7 OHM .50W 5% MF FUSIBLE.

I also have another problem the secondary voltage is measuring around 60V on my cheap DMM. This reading I am not willing to believe yet, because the low batt indicator is also on on the DMM, so tomorrow I will get new batteries and measure again.

Anyway, should I try shorting out R21 & 22 for now till I order replacements and go ahead?

Regards,
Dinesh
 
#409
Magura said:
I think we better leave this challenge for the designer :xeye:
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Magura,

My suspicion is on very high secondary voltage. The DMM needs new batteries and the reading cannot be trusted, which I will fix this evening. The high voltage probably destroyed the electrolytic caps (C2, C15, C16) which resulted in high currents through the resistors which blew it. Although there was no smoke, I think, I might as well get ready to order more caps.:bawling:
Dinesh
 
#410
dviswa said:


Magura,

My suspicion is on very high secondary voltage. The DMM needs new batteries and the reading cannot be trusted, which I will fix this evening. The high voltage probably destroyed the electrolytic caps (C2, C15, C16) which resulted in high currents through the resistors which blew it. Although there was no smoke, I think, I might as well get ready to order more caps.:bawling:
Dinesh
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Hi Dinesh.
Did you by accident connect the secondaries, wrong? It has happened before. Check the secondaries with your DMM (AC) to see if they are connected as they should be. It sounds like you could have two "hots" connected to one side of the psu.

🙂
 
#412
steenoe said:
Did you by accident connect the secondaries, wrong? It has happened before. Check the secondaries with your DMM (AC) to see if they are connected as they should be. It sounds like you could have two "hots" connected to one side of the psu.
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Steen,
I had the tech drawing from Plitron, it is a little unlikely. But yes, I agree, I will check again tonight and make sure I did not mess it up.

Magura said:
The key word here is as far as I'm concerned "FUSES" as in NO fuses.
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No Fuses I meant, the fuses on the board after the bridge and CRC. What I was trying to do is to make sure I was getting right voltages from trafo and bridge. Everythingelse, Shunty and Pumpy were not yet in the circuit. I have a fuse on the primary, which also blew out. 😱

Magura said:
Get yourself a handful of fuses, and try again after measuring the secondary voltage, BEFORE connecting the trafo.
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Hehe, do I have a choice?🙂
 
#413
@dviswa :

if you are using fusible resistors , sometimes they are more prone to burning than usual stuff ;

anyway - use 0W5 either carbon or MF with value of 2E2

I wrote that in Cook Book , in addendum ;

I have no these problems , because I use just 1mF caps in my Shunty , but sp300B was first who tell me for that problem ;

that's why I added that note .


regarding fuse in primary ......... 😕

be sure that secs are polarized/phased regularly , and that fuse isn't too dreky for xformer size.
 
#414
Zen Mod said:
@dviswa :

if you are using fusible resistors , sometimes they are more prone to burning than usual stuff ;

anyway - use 0W5 either carbon or MF with value of 2E2

I wrote that in Cook Book , in addendum ;
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ZM,
Sorry I did not see it. I will fix the values when I reorder.

Zen Mod said:
but sp300B was first who tell me for that problem ;
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Good to know that I am not the only one.


Zen Mod said:
regarding fuse in primary ......... 😕

be sure that secs are polarized/phased regularly , and that fuse isn't too dreky for xformer size.
Click to expand...

I verfied the connections and measured again. I am getting open loop 54-0-54 on the secondaries 😡 . Surely, way too high. I have requested the manufacturer to fix this, Let's see what comes of it. After that I have to order and replace all teh lytic caps.😱

Also noticed that my home supply is around 125V instead of the rated 110V 🙄
 
#417
Pumpkin volume control

steenoe said:


Me too😀 The pumpkin is getting a new home and bigger heatsinks , the case is with "see through lid"! Who could resist with all them green led's in there? Not me....

🙂
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So Mr. Steen, do I see potentiometers in place of the Twisted Pear stepped volume control and input-output boards?

Would you care to elaborate on the changes and effects on sound, if any? I would like to benefit from your experience and reasons for the changes. . .

Thanks!

Steve Z
 
#418
Re: Pumpkin volume control

zettelsm said:


So Mr. Steen, do I see potentiometers in place of the Twisted Pear stepped volume control and input-output boards?

Would you care to elaborate on the changes and effects on sound, if any? I would like to benefit from your experience and reasons for the changes. . .

Thanks!

Steve Z
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naah

don't count too much on his xperience ........ on next pic you'll see flies instead of pot :clown:

(talking about ........ once I mounted watering can instead of TV antenna on the roof , naturally with antenna cable connected to it ........ just to tease my neighbors .......... they have strange look few days ............ :rofl: )
 
#419
Steenoe's Pumpkin revised

Looking closer I see he had done away with input and output connectors too. Very nice trick -- two less connectors in the signal path. In fact, there are no connectors or controls anywhere on the new box! 😀

Steve Z
 
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