DC blocking caps for line level

Tenson · 30th October 2006, 03:17 PM

Hi,

I need to block 2.5V DC on a line level audio signal.

I have been trying a few caps and found that something like a 0.68uF polyprop cap introduced some levels of IMD and HD. I switched to a 0.1uF paper in oil and the HD reduced but the IMD increased. I then tried a 2.2uF PIO cap and the IMD also reduced.

So a bigger cap gives less IMD and paper in oil had less HD than a polyprop

Okay, so I tried a 22uF and an 11uF cheap electrolytic. The IMD reduced again but was about the same for both the 11uF and the 22uF (I have seen 10uF as a standard value for this before).

So my question is simply, what do you recommend as a good quality DC blocking cap? Is there any point going much above 10uF? Are there any drawbacks to using a very big value? and, what is the best type of cap?

Thanks to anyone who can enlighten me lol!

Cheers

Tenson · 30th October 2006, 03:51 PM

I found this article which is interesting. It shows why the PIO had less distortion than the polyprop I guess.

http://members.aol.com/sbench102/caps.html

So still, I wonder if there is any disadvantage to going above about 10uF?

Tenson · 30th October 2006, 04:35 PM

Okay I think the HD was a measurement glitch so the only thing was IMD from the value of the cap.

30th October 2006, 03:17 PM	#1
Tenson diyAudio Member Join Date: Feb 2006 Location: Kent	DC blocking caps for line level Hi, I need to block 2.5V DC on a line level audio signal. I have been trying a few caps and found that something like a 0.68uF polyprop cap introduced some levels of IMD and HD. I switched to a 0.1uF paper in oil and the HD reduced but the IMD increased. I then tried a 2.2uF PIO cap and the IMD also reduced. So a bigger cap gives less IMD and paper in oil had less HD than a polyprop Okay, so I tried a 22uF and an 11uF cheap electrolytic. The IMD reduced again but was about the same for both the 11uF and the 22uF (I have seen 10uF as a standard value for this before). So my question is simply, what do you recommend as a good quality DC blocking cap? Is there any point going much above 10uF? Are there any drawbacks to using a very big value? and, what is the best type of cap? Thanks to anyone who can enlighten me lol! Cheers

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Convert Line Level to Electric Guitar Level	miallen	Solid State	4	16th May 2010 01:22 PM
speaker level input vs line level question	crippledchicken	Subwoofers	4	17th July 2007 03:36 AM
lesser of two evils, high level -> line level, digital volume control	mazurek	Solid State	3	19th November 2006 12:25 AM
how to bring down line level signal to preamplifier level	deji	Solid State	15	15th April 2004 04:13 PM
Using speaker caps in line level applications?	Hybrid fourdoor	Chip Amps	8	16th September 2003 12:42 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

30th October 2006, 03:51 PM	#2
Tenson diyAudio Member Join Date: Feb 2006 Location: Kent	I found this article which is interesting. It shows why the PIO had less distortion than the polyprop I guess. http://members.aol.com/sbench102/caps.html So still, I wonder if there is any disadvantage to going above about 10uF?

30th October 2006, 04:35 PM	#3
Tenson diyAudio Member Join Date: Feb 2006 Location: Kent	Okay I think the HD was a measurement glitch so the only thing was IMD from the value of the cap.