Tantalum cap to set gain in LM386 - Page 3 - 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 27th June 2011, 03:01 PM   #21
diyAudio Member
 
Join Date: Jun 2011
Quote:
Originally Posted by AndrewT View Post
82dB/W @ 1m is far too low for battery powered anything.
However, it's 16ohm, which means more output power. If I used an 8ohm with say 85db SPL, the difference in volume...I THINK...would be marginal.

Your judgement is better than mine of course, but maybe I'm somewhat right?
  Reply With Quote
Old 27th June 2011, 03:17 PM   #22
diyAudio Member
 
Join Date: Jun 2011
How about this one: GRS 5SBM-8 5" Sealed Back Midrange

It's a tad more expensive, but 89db SPL.

I realized that since it's going to be using a 9V battery that an 8ohm driver would perform the best in this instance. 16ohm would be better if you had 12-16V, but since it'll be 9V, 8ohm will give the most power. It's a sealed chassis, so I won't need to make the enclosure any bigger than it needs to be. According to one of the reviewers, I can make a HFP of 800hz with a 8uF cap.

It also has a grille over it, which I was a little bit concerned about before...

Is this an "ideal" driver?
  Reply With Quote
Old 27th June 2011, 07:49 PM   #23
! is offline !  United States
diyAudio Member
 
Join Date: Jun 2005
Location: Midwest
The GRS driver would be easier to implement mechanically, since you don't have to worry about enclosure acoustics nor add protection (grill) to the front yourself, but the sealed back comes at a cost, low end frequency range going down to only 600Hz, which is a pretty bad limitation as that cuts into the lower midrange frequencies you hear on things like the human voice. Also, it is not shielded, you would have a huge magnet close to your audio signal in a small enclosure, which hypothetically is bad but in this instance I don't know if it would make a difference.

Although not as DIY, one option for higher efficiency running off the 9V battery and to slash construction time and add-on parts costs, from Parts Express if you're ordering stuff there anyway to offset the shipping cost, would be a ready made class D amp module. $14 Sure 2x2W @ 4 Ohm Class-D Audio Amplifier Board

It seems like the best option for 9V battery power, IMO, or you might find something similar on ebay cheaper if you have a few weeks to spare waiting on airmail from Hong Kong/etc.

Otherwise, I agree that with 9V power source you probably want to stay with an 8 Ohm speaker with LM386 and epoxy a little heatsink on top if it gets hot in bench testing, but I keep ignoring the idea of keeping the cost low. If you can sacrifice the volume and since it's running from only <=9V, your LM386 will do that, the rest is a matter of frequency response vs acoustics and the protective grill. I guess my point is you can't have everything with low cost and power, and we can't decide for you which tradeoffs to make.

Last edited by !; 27th June 2011 at 08:05 PM.
  Reply With Quote
Old 27th June 2011, 08:00 PM   #24
Banned
 
Join Date: Nov 2006
Location: Torpoint
This is going very off topic. What have drivers got to do with tantalum capacitors ?
  Reply With Quote
Old 27th June 2011, 08:03 PM   #25
! is offline !  United States
diyAudio Member
 
Join Date: Jun 2005
Location: Midwest
^ hehe, true enough the topic probably ought to be renamed 9V battery powered LM386 project or something like that.
  Reply With Quote
Old 27th June 2011, 09:56 PM   #26
diyAudio Member
 
Join Date: Jun 2011
Can a moderator do that? It might be more helpful for other people to add something to the title.

By the way guys, I decided to buy that $1.50 3 x5inch driver that was recommended first. After contemplating about 10 different drivers, that has the best pictures of quality (cloth surrounds better than the paper surrounds, i think), SPL (89.6db), cost ($1.50), and frequency response.

The only problem I might have is jigging out a 3 x 5 hole. That's sort of a nasty bend, but it can be done. After further inspection, the driver is actually made by Matsushita (Panasonic), my favorite electronics supplier.

And the D-Amp looks nice...but I'm trying to go for a more "DIY" feel, maybe so I can get him into DIY too. Soldering an 48pin SMD might not be the best thing to show a newbie.

Thanks.
  Reply With Quote
Old 28th June 2011, 11:31 AM   #27
diyAudio Member
 
digits's Avatar
 
Join Date: Apr 2011
All the gain thing does on those chips with a guitar connected is give you a light distortion effect, kinda like a pedal... I've build one for a friend before. I just made a samll open baffle board he could prop up against whatever.
  Reply With Quote
Old 28th June 2011, 03:20 PM   #28
diyAudio Member
 
Join Date: Jun 2011
Cool! I think the ribbed design of the $1.50 driver I bought will actually help with guitar/bass. A lot of nice guitar amps like to use ribbed drivers, so maybe it will help somehow too?
  Reply With Quote
Old 30th June 2011, 11:43 PM   #29
! is offline !  United States
diyAudio Member
 
Join Date: Jun 2005
Location: Midwest
It would help keep the cone from deforming if you were feeding it a lot more power than LM386 can supply.
  Reply With Quote
Old 1st July 2011, 04:07 PM   #30
diyAudio Member
 
Join Date: Jun 2011
Oh by the way, I built the circuit.I tried it initially with a gain of 200, and there was waay too much distortion, especially when the battery is running low on juice. I wound up actually liking the default gain of 20, which is leaving pins 1 and 5 empty. Least distortion, and it's still plenty loud. I tried the bass boost. Sounded okay, however, it's adding a measure of distortion as well, especially at higher volume levels. The drivers the LM386 are also not the best drivers ever, and there is no band filter to cut back on distortion.

After determining what I wanted, I transferred the circuit to some perforated board, and noise was significantly reduced. Almost sounds good!

Thus I think using the simplest LM386 circuit will yield the best overall results, for something like your iPod or computer. I tested it with a small cheap 8ohm paper speaker, which I'm thinking might have sufficed, instead of ordering one from Parts Express. Oh well.
  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 01:45 PM.


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