Tantalum cap to set gain in LM386 - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

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
Reply
 
Thread Tools Search this Thread
Old 26th June 2011, 12:55 AM   #1
diyAudio Member
 
Join Date: Jun 2011
Default Tantalum cap to set gain in LM386

Hi,

I know this isn't exactly hi-fi, but I'm building a friend a small amp for his birthday, and I'm looking for some help on parts selection.

I'm following the National schematic for setting the gain to 200. The vale to achieve a gain of 200 is a 10uF capacitor. Obviously, I could just use a 10uF electrolytic and call it a day, but what would happen if I put something like a 10uF tantalum in there...for kicks.

Would changing from a electrolytic to a tantalum have any difference in sound (in this application)? Is it worse or better? Tants are supposed to be better quality, but I'm just curious.

Thanks.
  Reply With Quote
Old 26th June 2011, 10:15 AM   #2
enzoR is offline enzoR  Netherlands
diyAudio Member
 
Join Date: Mar 2008
are you sure you want a gain of 200?

anyway electrolytic or tant wont make a difference in this application.
  Reply With Quote
Old 26th June 2011, 10:41 AM   #3
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
I don't know the internal circuit, but I suspect the external cap is AC bypassing an internal gain setting resistor.
If that is the case then adding a series resistor with the cap should allow an intermediate gain setting.
__________________
regards Andrew T.
  Reply With Quote
Old 26th June 2011, 10:47 AM   #4
diyAudio Member
 
Join Date: Jan 2002
Location: Tyrone Ga. U.S.A.
Going to a tantalium cap is probably a bad idea they sound bad. And by the way tantalium caps are electrolitic.
  Reply With Quote
Old 26th June 2011, 11:38 AM   #5
diyAudio Member
 
digits's Avatar
 
Join Date: Apr 2011
Sound bad is a relative thing in this particular function, which is to try to add some grunge to a toy guitar amp....
  Reply With Quote
Old 26th June 2011, 06:26 PM   #6
diyAudio Member
 
Join Date: Jun 2011
I have a question regarding gain..anyway. I know what the textbook definition of gain is, but I don't understand what it really means for sound/sound quality. It should be louder right? So...what would be the point of using a low gain?

Sorry if this a big quesiton.
  Reply With Quote
Old 26th June 2011, 08:22 PM   #7
diyAudio Member
 
sofaspud's Avatar
 
Join Date: Nov 2005
Location: San Antonio
Gain doesn't mean anything to sound/sound quality. If you want a 12V output, you can amplify a 1V signal 12x, or a 3V signal 4x, or an 8V signal by 1.5x. That's the reason for the question in post#2; 200x gain is likely to clip all but the smallest of your input signals. On the other hand, 200x may be what you need. It's nothing to do with loudness though. The LM386 has a specified output capability of watts into a load. The amount of gain doesn't change that. "It should be louder right?" is a big reason why there's a steady stream of "this car amp is broken" posts.
__________________
It is error only, and not truth, that shrinks from enquiry. - Thomas Paine
  Reply With Quote
Old 26th June 2011, 09:42 PM   #8
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
Gain should be kept as low as possible to get full output power.
The more gain the more you are amplifiying noise from components.
My amps usually have a gain for about 45.
  Reply With Quote
Old 26th June 2011, 09:44 PM   #9
diyAudio Member
 
Join Date: Jun 2011
Thanks.

I'd like to remind you that I'm an idiot...

I understand now. I'm assuming that my friend will predominatley be using this with his Zune HD, but I also am including the option to use a 1/4inch input (like his guitar) and I'm using a DPDT switch to switch the mono signals. (3.5mm jack and 1/4inch jack).

So what is a "normal" voltage output from a Zune/iPod?

Thanks.
  Reply With Quote
Old 26th June 2011, 09:58 PM   #10
diyAudio Member
 
Tube_Dude's Avatar
 
Join Date: Mar 2002
Location: Aveiro-Portugal
Quote:
Originally Posted by woody View Post
And by the way tantalium caps are electrolitic.
Hi Woody

Tantalum capacitors are solid capacitors, not electrolytic in any way...

Maybe you mean they are polarized capacitors, like electrolytics are.
__________________
Jorge
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
tantalum cap Nikon1975 Tubes / Valves 4 23rd January 2010 08:13 AM
Using a Voltage Meter to set your amp gain? Flyin11 Car Audio 29 2nd February 2008 09:03 PM
tantalum cap leakage? AndrewT Parts 5 12th December 2005 10:35 PM
How to set AC current gain in Aleph-X ? yoke Pass Labs 11 26th August 2004 08:12 AM
Tantalum cap identificaton. Please help. sv Parts 1 1st April 2004 01:31 AM


New To Site? Need Help?

All times are GMT. The time now is 08:23 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2