Pumpkin preamp - ordered by Steen , official making thread

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#1,085
hershann said:


Pardon my poor comprehension - so you mean -ve leg of electrolytic to output of film cap and +ve leg of electrolytic to resistor which is then connected to ground. So the electrolytic is not actually parallel to the film cap at all.
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steenoe said:


Your drawing is not excactly correct! The Electrolytic cap must be in parallel with the outputcap. Said in another way; you can replace the outputcap, with the electrolytic (and add the resistor as Mr. ZM said)

🙂

Edit: And bypass the electrolytic with your faverourite filmcap ofcourse😉 I beleive there is provided for that on the Shunty boards...

Edit Edit: I would use at least 220uF, and even that, I feel is too small. I usally go for 1000uF for headphone applications like that.
One good combo that I can recommend is 470uF Panasonic FC bypassed with a 1uF Rifa PHE426 polyprop. At least that is the best sounding "cheapo" combo that I have ever heard😉 Using a smallish cap on the output of a Headphone amp does cut the lower octaves somewhat😉
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In that case - it's just replacing the output cap or paralleling the output cap with an electrolytic then. Since there is already a R27/R29 (100k) shunting to ground, why is there a mention of having a 47k ohm resistor connected to ground? Is that to replace R27/R29?

Will the electrolytic cap degrade the sound somewhat when the pumpkin is used as a preamp then?

her shann
 
#1,088
Variac said:


Yup I was trying to be clever. I know that inductance isn't important for DC so my point is that an inductive resistor is actually better in the power supply as it might (theoretically ) filter out a teeny bit noise and ripple. So part of point was that those who would blindly replace resistors with a "better" non-inductive one might be wrong...

I will never try to be "clever " again...promise...
😀
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burlesca wasn't comment of your post , in any meaning ;

as steen sez - that was clever question

I meant really on entire thread - in positive meaning ............

ou contrary to some other threads ( not just these days) this one is full of positive madness
 
#1,097
I know there has been many discussions about output capacitors. I am thinking of using these:

http://cgi.ebay.com/Obbligato-Premi...eZWD1VQQtrksidZp1638.m118.l1247QQcmdZViewItem

Just wondering if off board mounting (as these are too big) are a bad idea for output caps? - I know off board mounting can be bad for power supply caps due to the long leads.

Or should I just stick to something that can fit the footprint - like the Wima MKP4, Epcos film cap, Mundorf (cheap series)🙄 . The really expensive boutique caps can clean out my wallet really fast. (need 4 with Pumpkin!
😱

her shann
 
#1,099
Oh, Man!......I've bee trying to read through this thread, but this combination of Elephant beer and Slivovic just makes my head spin....:clown:

Since I'm in a situation of just being able to continue to gather information for yet another year ( hopefully less), I just wonder if the PCBs for Pump&Shunty were public... can't seem to find them?
 
#1,100
AuroraB said:
Oh, Man!......I've bee trying to read through this thread, but this combination of Elephant beer and Slivovic just makes my head spin....:clown:

Since I'm in a situation of just being able to continue to gather information for yet another year ( hopefully less), I just wonder if the PCBs for Pump&Shunty were public... can't seem to find them?
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nope 😉

I think that these few treads , schematics and Cook Book are enough ......... :devilr:

but I'll not make any fuss if someone publish his own variant ......... :rofl:
 
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