I'm building a Combo Amp for someone.

The cabinet is Pine 13" wide x 15" tall and 11" deep. All glued together and used a 1/2" roundover bit in my router for the edges.

The speaker is a vintage 10" Utah 15W 8ohm. The amp is my dual Im386 chip bridged amp design. Can run on 9volt battery or walwart and output is 1 to 2 watts.

Views: 2411

Replies to This Discussion

Sure. Any cap with equal values will work fine. I use small electrolytic polarized versions in 220uF/35v. You could use anything from 100uF for a bright sound, and up to 250uF for more low end sounds.

Or even add a switch between two values.

Voltage rating can be from 16v-50v. *( If using the LM386N-4 chip at the 18v max., the cap should be at least 35v.)

Well the DUH award of the week goes to me. Turns out that my schematic shows grounding the wrong side of the pots and I thought they were turned all the way up, but they were all the way down. DUHHHH

The 2 input jacks being tied together at the volume pot isn't working well. The switch option for either this cap or that one was better.

2 volumes pots aren't needed since both end up being turned all the way up anyway. 1 pot is all that's needed.

Need to draw up a new schematic. One that's correct wouldn't hurt either.

The first version of this amp that I made was perfect, this build has fought me at every turn.

Got everything working. It's got some hum coming through the speaker. Put some caps in the output lines to the speaker(2-100uf and then 2- 220uf), that got rid of the hum for the most part and added some volume. Also distorted the speaker too much. Tried a couple of other speakers to rule out a speaker problem, same results.

I'll do some more trouble shooting and try some other things this afternoon.

That was bad. LOL

I'm going to recheck all the grounds, think that has a lot to do with most if not all the hum.

May also try some smaller caps in the output circuit. Got some 10uf, .047 and .022. just have to find the right ones.

The little things can be a real pain. Checked all the solder joints and they're good.

I had some 3.3uf caps that are working very good. With all 4 controls turned all the way up, the speaker still distorts more than it should. Now I'm beginning to think the speaker cone is half shot. The speaker is rated at 15 t0 20 watts at 8ohms and should be able to handle this 8ohm 1 to 2 watt amp without issues.

https://wgs4.com/vet10

Thinking this will do nicely.

WGS also has a 8" for 31 dollars so I may go that route and check it with the 220uf caps that the Ruby amp uses.

I've listened to the Jensen Mod speakers and the WGS speakers sound bites/videos on youtube and various other sources over the past couple years. The WGS speakers sound much better and the price is close to the same.

Thanks for your help looking those up, I appreciate it.

Hey Finder,

Yes, a 2 or 3 watt amp will drive a 20 watt speaker. Even my small 1/2 watt circuits can do that.

The second and third units you linked are 2 channel (stereo) circuits designed to process the signal from MP3, hi-fi, etc. and into dual independent speakers (stereo).

They will not distort like a guitar amp circuit without using an effects pedal. Instead, their tone/sound is clean.

The first unit is not an amp, but a bass/treble/tone adjustment circuit designed to be connected to another amp board.

As to your last question, a volume pot in an amp simply regulates how much of the guitar pickup signal enters the amplifier, or in the case of tube amps, they regulate the signal flow after the first pre-amp stage. Both the volume and tone pot will often have a capacitor to bleed off certain frequencies.

Often, these pre-made boards will have a range of operating voltage recommended. (i.e. 4-12vdc). One can choose to go with the minimum or maximum voltage. But in many cases, a mid-range of power will result in the amp sounding it's best. So, for example, the LM386N-1 IC chip is rated at 4-12vdc. But it sounds best overall at 9vdc, due to how the IC reacts to different voltages and it's designed output.

Thanks for that Scott.

The watt ratting for a speaker is the suggested limit of output wattage. So they will handle anything from 1/2 watt to 20 watts, anymore than 20 will damage the speaker.

No, the PCB board is not under production nor is it available for sale.

The circuit Paul is using is like the Little Gem MK2, which uses the two LM386 IC chips. The schematic is owned by Runoffgroove.com, and is made public only for single use personal projects, not for commercial production. There is a PCB layout available by Pablo de Luca, for those who want to make a professional etched PCB.

For those who wish to pursue building these circuits to make amps for sale, permission can be obtained by contacting the host at runoffgroove.com

I noticed the Little Gem MK2 doesn't use buffer caps in the output circuits either.

When I get the new speaker, I'm going to back through all the cap values again to get the right ones. The 220uf like the Ruby uses was good till the second gain was dialed up, just not sure how much of the bad was cause of the speaker.

RSS

The Essential Pages

New to Cigar Box Nation? How to Play Cigar Box GuitarsFree Plans & How to Build Cigar Box GuitarsCigar Box Guitar Building BasicsCigar Box Guitar Parts Store

Site Sponsor

Recommended Links & Resources


Discussion Forum

LM386 Amp w/ Switchable Clean Channel

Started by BrianQ.. Last reply by BrianQ. May 28, 2021. 1 Reply

Simple 1st Timer CBG Amp

Started by BrianQ.. Last reply by BrianQ. Sep 28, 2020. 25 Replies

Matching Speakers to LM386

Started by Southern Ray. Last reply by Southern Ray Aug 6, 2020. 11 Replies

Suggestions wanted for easy amp build

Started by Southern Ray. Last reply by Southern Ray Jun 16, 2020. 11 Replies

Ruby Amp

Started by BrianQ.. Last reply by Southern Ray May 17, 2020. 27 Replies

Low-Z pickup and components values

Started by Southern Ray. Last reply by Southern Ray May 13, 2020. 6 Replies

Oops

Started by Southern Ray. Last reply by Southern Ray May 3, 2020. 12 Replies

DIY Spring Reverb

Started by Kevin Keating. Last reply by Paul Craig Oct 17, 2019. 4 Replies

TDA2030A Amp

Started by Bama Hound. Last reply by Gary Stenzel Jul 23, 2017. 14 Replies

Home Brew Champ Tube Amp

Started by Scott aka Farmer Ted. Last reply by Paul Craig Feb 6, 2017. 3 Replies

Dual IM386 Chip amp

Started by Paul Craig. Last reply by Paul Craig Jan 27, 2017. 29 Replies

5 Watt Amp Kit (DIY Case)

Started by Walter Haapapuro. Last reply by Gene Jones Dec 7, 2016. 46 Replies

DIY reverb behold - I found this online

Started by Danny B.. Last reply by Paul Craig Nov 2, 2016. 3 Replies

Bass Cabinet project

Started by Murdoc_420. Last reply by Murdoc_420 Jul 16, 2016. 34 Replies

Kalamazoo Model 1 Deluxe

Started by Scott aka Farmer Ted. Last reply by Rick Alexander Jun 20, 2016. 12 Replies

LM386 amp and other stuff

Started by Denis U. Last reply by Denis U May 29, 2016. 19 Replies

Combo Amp Build

Started by Paul Craig. Last reply by Paul Craig May 27, 2016. 113 Replies

Latest Activity

Michel liked Rob Uker's photo
1 hour ago
Rob Uker commented on Jim Winslow's photo
Thumbnail

509D8F2B-B281-484A-88A7-468F8B08AFF2

"Nice Danelectro inspired Longhorn."
3 hours ago
Rob Uker liked Jim Winslow's photo
3 hours ago
Darryl Tuttle commented on Randy S. Bretz's photo
Thumbnail

Cherry bench done

"Looks like the perfect bench to sit and play guitar"
5 hours ago
Infirmity Citrus President posted a discussion

The entirely hypothetical encylopedic CGB design and construction book - a long post

I just bought a box full of CGB building books, and I must say I'm disappointed. I taught…See More
7 hours ago
BrianQ. commented on Randy S. Bretz's photo
Thumbnail

Cherry bench done

"I would too!!!"
8 hours ago
Randy S. Bretz posted a photo

Cherry bench done

My wife said she loves it !
8 hours ago
Uncle John commented on Matthew Borczon's video
Thumbnail

Dinks song

"Thanks a lot, Matt. '"
10 hours ago
Maddog commented on the anonymous pick's blog post UPDATE on my health issues
"I have not been on CBN for some time but did see your message a few days ago and needless to say…"
10 hours ago
Keith Rearick liked Poorness Studios's video
11 hours ago
Keith Rearick liked Matthew Borczon's video
11 hours ago
Keith Rearick liked Pavel Danilov's video
11 hours ago

Events

Music

© 2022   Created by Ben "C. B. Gitty" Baker.   Powered by

Badges  |  Report an Issue  |  Terms of Service

\uastyle>\ud/** Scrollup **/\ud.scrollup {\ud background: url("https://storage.ning.com/topology/rest/1.0/file/get/963882636?profile=original") no-repeat scroll 0 0 transparent;\ud bottom: 25px;\ud display: inline !important;\ud height: 40px;\ud opacity: 0.3 !important;\ud position: fixed;\ud right: 30px;\ud text-indent: -9999px;\ud width: 40px;\ud z-index: 999;\ud}\ud.scrollup:hover {\ud opacity:0.99!important;\ud}\ud \uascript type="text/javascript">\ud x$(document).ready(function(){\ud x$(window).scroll(function(){\ud if (x$(this).scrollTop() > 100) {\ud x$('.scrollup').fadeIn();\ud } else {\ud x$('.scrollup').fadeOut();\ud }\ud });\ud x$('.scrollup').click(function(){\ud x$("html, body").animate({ scrollTop: 0 }, 600);\ud return false;\ud });\ud });\ud \ua!-- End Scroll Up -->