EAR 834P

[Demsy]

Hi,
I want to replace the coupling caps of the above mentioned phono preamp. There are 2 capacitors, 0,15uF/250v near V1, and another one is 1uF/250v at V3. I don't have 0,15uF but I do have 0,1uF cap, would that be okay to use? And what to expect using that value?
Thanks in advance!

[Grainger49]

The true frequency response depends on the impedance it is driving.  It may also interact with the output impedance of the tube as well.

The formula is 1/2(Pi)RC

That is one divided by the constant 2 times Pi (3.1416) times the resistance of the amp's input times the capacitor value. 

1uF is 0.000001 in this formula.

This gives the 3dB down point.  The flat response is ten times the 3dB down point. 

In reality most of us don't have rooms large enough for a 20 Hz response.  But designers work to make their equipment flat at 20 Hz.

[RayP]

Take a look at this post on substituting parts for the EAR834P. It's about half way down the page. I make no recommendations for any of the changes as I just happened to find the post.

http://www.hifiwigwam.com/showthread.php?4077-Intresting-valve-rolling-and-EAR-834P-(if-your-interested)

A Google search for the schematic comes up with quite a few results.

ray

[Demsy]

Thanks Grainger and Ray. I have read the postings of Romy earlier, quite interesting.