B1 output at power up

B1 buffer DC offset at power up and power down

Hello DIY'ers

I have build me a B1preamp... and it works, so far so good.

I use two 12v batteries for power in series and I noticed that when switching on theres an initial output/offset of about 400mv that drops over a couple of minutes to 0, and when I switch it off theres a brief output of about 1200mv

My question is, is this normal or have I messed something up?, the reason im asking is because my power amp, a Charlize 2 from diyparadise
cannot handle this initial offset as she has no caps to protect her.

If this is not normal, can anyone give me a pointer to what I should have a closer look at?

I thought I could simply put a relay with a delay in there somewhere to activate the output after a couple of minutes, but if I could avoid that it would be best of course.

Thanks
 
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Hi,

if you have the B1 as Mr. Pass intended, there is a big cap at the output to block DC from the following amp. I guess the offsets you measure on switch on/off are because the cap in the output charges/discharges slowly. You can look how this is solved in the DCB1 Hypnotize/Mezmerize implementation. There is a simple solution to enable the output with a delay and disable it the moment the preamp is switched off.

Br
Josch
 
Hi,

if you have the B1 as Mr. Pass intended, there is a big cap at the output to block DC from the following amp. I guess the offsets you measure on switch on/off are because the cap in the output charges/discharges slowly. You can look how this is solved in the DCB1 Hypnotize/Mezmerize implementation. There is a simple solution to enable the output with a delay and disable it the moment the preamp is switched off.

Br
Josch

Hi Joschl, thanks for your reply, I think I'll try this solution incorporating a relay with a delay.
 
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