Pumpkin preamp - More Boring Making Thread

[Variac]

I just thought it amusing that inductive might be more desireable because they might in fact reduce ripple a little. and more expensive non- inductive would be worse..I know the amount is teeeeny though

[Magura]

Originally posted by Zen Mod



why you didn't asked ?

either increase current through input LTP , or increase values of theirs drain resistors ........... or slightly decrease source resistors of outputs .....that last is maybe best solution

It's in the tube for future playing around. As for now I'm waiting for the boards.
I though did some playing around with my previous prototype, and 200mA seems to be the point of diminishing returns.

I can't be bothered to make a birds nest, when I know that boards are coming soon.....and besides that I have other things to play with ATM

Magura

[Zen Mod]

Originally posted by hershann
For the Pumpkin - assuming the max output cap of 10uF - I guess it will still not be adequate for a headphone with input impedance of 300ohm as the LP filter will still be loping off a huge chunk of the bass.

Thinking of using the balanced output to do double duty to drive a balanced headphone too. I guess the only for this is to add an electrolytic

her shann

you can find decent electrolytics in range 100-220 uF, and you can bypass them with something nice , in range of 1-2u2 ;


just hang them ( electrolytics)on inner side of present output caps , solder 47K from output side of caps to gnd ( for bleeding those big caps ) , connect da cans and enjoy .

as I said - I tried my proto Pumpie with AKG K270 Studio ........

nota bene - do not forget to power off power amp, when you are in mood for headphones ........

naaaaaaaah......

I'm ill like a dog ........ flue almost gets me completely ..........

[Manu]

Maître Zen,

With AKG 270 corner freq will be about 20Hz with 100uF cap. Is it still oK,
or is it best to go 220uF in any case?

I'm ill like a dog ........ flue almost gets me completely ..........

Wish you speedy gonzales recovery...

[hershann]

Originally posted by Zen Mod



you can find decent electrolytics in range 100-220 uF, and you can bypass them with something nice , in range of 1-2u2 ;


just hang them ( electrolytics)on inner side of present output caps , solder 47K from output side of caps to gnd ( for bleeding those big caps ) , connect da cans and enjoy .

as I said - I tried my proto Pumpie with AKG K270 Studio ........

nota bene - do not forget to power off power amp, when you are in mood for headphones ........

naaaaaaaah......

I'm ill like a dog ........ flue almost gets me completely ..........

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.

[steenoe]

Originally posted by hershann


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.

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

[Variac]

Biggest Burleska

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...

[steenoe]

Originally posted by Variac


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...

Naah, dont think so. First you were right, then you were right again!!!! Use the most inductive resistor that you can find for CRC arrangements"!!!"
You better play "clever" some more

[hershann]

Originally posted by hershann


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.

Originally posted by steenoe


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

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

[Zen Mod]

Originally posted by hershann


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.