Bride of Zen

[meanman1964]

I'm planning to build this preamp and I have a few questions.Personaly,I think the input cap(C104/1µF) need to be a good one a Tin folie or better but what about the output cap(C103/10µF)?

 

[GRollins]

Use a good cap. If necessary, bypass with a decent film cap.

Grey

 

[Zen Mod]

I'm planning to build this preamp and I have a few questions.Personaly,I think the input cap(C104/1µF) need to be a good one a Tin folie or better but what about the output cap(C103/10µF)?

is this a trick question?

if signal goes through both caps,conclusion can be just one............

 

[meanman1964]

Re: Re: Bride of Zen

is this a trick question?

if signal goes through both caps,conclusion can be just one............

Why do you think this is a trick question?
If you can give me some good advice about building this preamp feel free.

 

[Zen Mod]

Re: Re: Re: Bride of Zen

Why do you think this is a trick question?

just because answer is perfectly clear from question..................

never mind;look at few pics:

http://choky.on.neobee.net/My_BOZ.html

 

[meanman1964]

Use a good cap. If necessary, bypass with a decent film cap.

Grey

What about bypass with a Styroflex or a Roederstein MKP 1837

 

[meanman1964]

Can I use a bigger output pot?Like 50K instead of 5K,so I can lower the output cap from 10µF to 2.2µF.

 

[GRollins]

The value of the DC blocking cap at the output is dependent not only on the value of the pot, but also on the input impedance of the amplifier.

Grey

 

[Spirtos]

Hi,
using the original value for the volume pot, the output impedance will be 0- 1,5k depending on the position of the volume pot. If you increase it, the output impedance will be increased too. This would be a problem for your power amp if it has low input impedance.
I have used a 10uF SCR polypropylene cap for output with good results. It's too expensive to use something "great" in this value.

Regards
Spiros

 

[meanman1964]

Hi,
using the original value for the volume pot, the output impedance will be 0- 1,5k depending on the position of the volume pot. If you increase it, the output impedance will be increased too. This would be a problem for your power amp if it has low input impedance.
I have used a 10uF SCR polypropylene cap for output with good results. It's too expensive to use something "great" in this value.

Regards
Spiros

Hi,
Look at the Sewa tread post #655
I'm wondering if I could replace the MKP 10µF for a 8.2µF?

 

[Spirtos]

Hi,
you can decrease the capacitor value and increase the pot value,
BUT keep in mind the basic rule for amplification stages: For adaptation between two stages, you need source with at least 10 times smaller output impedance than load's input impedance. Also, in this circuit , the total output impedance is a combination of R104 (1K), mosfet IRF610, C103 (10uF), and volume pot (5K). I use a 10k Alps Blue pot in my BOZ, but my poweramps (so far) have more than 33K input impedance...so...



Spiros

 

[Spirtos]

I'll try to be more clear.

The low cut-off frequency is:

f= 1/ 2π * (RD + RL) * C

where RL= volume pot, RD=R104, C=C103 in the original schematic. Moreover, you have the poweramp input impedance which must be 10 times bigger than preamp's output impedance, otherwise you'll have limitation in frequency responce.

Regards

 

[meanman1964]

Hi,
My amp has an input impedance of 47Kohm.Its a Aleph 30 and I have a ZV9 and a OTA.