Welcome, Guest. Please login or register.

July 24, 2021, 07:59:21 PM

Login with username, password and session length

Recent Posts

 

Author Topic: Power supply suggestions  (Read 901 times)

mattbianconi

  • Regular
  • **
  • Posts: 11
  • Chip Points: 2
    • View Profile
Power supply suggestions
« on: May 20, 2021, 03:04:52 PM »
I got the kit that came with the 8 ohm speaker.  All assembled and currently powered with a 9-volt battery.  It seems I have to have the volume absolutely cranked to be heard over the guitar strings themselves. Turning the gain up obviously gets past this a bit.
I tried to use a 12 volt DC wall plug but that introduced a ton of hum into the amp.
What are you using as power for this little guy? Would an A23 battery work?
Thanks

galaxiex

  • Legendary
  • ******
  • Posts: 543
  • Chip Points: 51
    • View Profile
Re: Power supply suggestions
« Reply #1 on: May 20, 2021, 06:30:21 PM »
I got the kit that came with the 8 ohm speaker.  All assembled and currently powered with a 9-volt battery.  It seems I have to have the volume absolutely cranked to be heard over the guitar strings themselves. Turning the gain up obviously gets past this a bit.
I tried to use a 12 volt DC wall plug but that introduced a ton of hum into the amp.
What are you using as power for this little guy? Would an A23 battery work?
Thanks

Install a 10uf cap on pins 1 & 8 to maximize the gain.
The pads are on the board so it's easy to do.
If it ain’t broke I’ll fix it until it is.

mattbianconi

  • Regular
  • **
  • Posts: 11
  • Chip Points: 2
    • View Profile
Re: Power supply suggestions
« Reply #2 on: May 20, 2021, 10:48:51 PM »
Thanks, I'll try that and see how that sounds.

joecool85

  • SSGuitar Admin
  • Legendary
  • ******
  • Posts: 3409
  • Chip Points: 993
  • SSG Creator
    • View Profile
    • thatraymond.com
Re: Power supply suggestions
« Reply #3 on: May 21, 2021, 10:33:58 AM »
To get the most clean sound out of it you will want 12v or so.  I use a 12v SLA that I have hooked up to solar for charging my cell phones and other devices at home.  While it works well, clean power is limited on this little guy.  The best clean sounds can be had with higher voltage and a 16 ohm speaker with high SPL ratings. 

The 4" speaker sold with the kit is rated for 90db @ 1w.  This is fantastic for such a small speaker (most this size are between 83 and 86db, sometimes lower).  Large guitar speakers can be significantly higher than this though.  Many 12" speakers are around 102db @ 1w.  This means it would be over twice as loud for the same wattage going into the speaker.  So, for max volume, a 12" guitar speaker at 16 ohms, rated at 102db/w and using a power supply of 16v power supply (yielding 1.2w clean power) would give you 103.6db at 3'.  To put this in perspective, your current situation running on 9v with an 8 ohm load (yielding 0.5w clean) on the stock 90db/w speaker gives only 87.8db at 3'.

Your options on the stock speaker are to increase power to 12v which does give you a little bit more headroom (a total of 0.6w clean or so) and then you can play with increasing the gain on the LM386.  I think you'll find though that given that small speaker, that's about as loud as you will get clean.  If you find a way though, please share!  I love being wrong on this kind of thing!
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

mattbianconi

  • Regular
  • **
  • Posts: 11
  • Chip Points: 2
    • View Profile
Re: Power supply suggestions
« Reply #4 on: May 21, 2021, 11:23:12 AM »
Thanks for the clear explanation and comparisons joecool85.  I'll keep playing around and digest the circuit more to try and understand what I'm doing. Always learning. 

joecool85

  • SSGuitar Admin
  • Legendary
  • ******
  • Posts: 3409
  • Chip Points: 993
  • SSG Creator
    • View Profile
    • thatraymond.com
Re: Power supply suggestions
« Reply #5 on: May 21, 2021, 11:36:20 AM »
Also, if you are looking at only using this clean, you might want to consider running this without the overdrive circuit at the front.  The board is set up to be able to run the MPSA13 as a buffer in front of the LM386 if so desired.  I had thought this would mostly be for a bassist or keyboard etc, but could be used for clean guitar for sure.  The notes for "clean buffer mode" are on the bottom of the schematic.
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

mattbianconi

  • Regular
  • **
  • Posts: 11
  • Chip Points: 2
    • View Profile
Re: Power supply suggestions
« Reply #6 on: June 17, 2021, 02:05:56 PM »
Thanks everyone. I put the 10uf cap in and its doing great.  Love the gain sound actually. 
I put it in a 221x150x63.5mm case that I had from mouser. Just want to really thank everyone for this forum and this cool project.

joecool85

  • SSGuitar Admin
  • Legendary
  • ******
  • Posts: 3409
  • Chip Points: 993
  • SSG Creator
    • View Profile
    • thatraymond.com
Re: Power supply suggestions
« Reply #7 on: June 20, 2021, 08:13:35 PM »
Thanks everyone. I put the 10uf cap in and its doing great.  Love the gain sound actually. 
I put it in a 221x150x63.5mm case that I had from mouser. Just want to really thank everyone for this forum and this cool project.

Good job, Matt - very professional build!
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

TheBobbyElectric4

  • Chipper
  • *
  • Posts: 7
  • Chip Points: 1
    • View Profile
Re: Power supply suggestions
« Reply #8 on: June 30, 2021, 08:58:30 AM »
....and, on that note.


Here is another Matt, with the exact opposite experience. Hahaha!

I couldn't find a decent enclosure, so I happened to find this Kleenex Box randomly, so.... Yep. I stuck it in a Kleenex Box.

For now, at least.


joecool85

  • SSGuitar Admin
  • Legendary
  • ******
  • Posts: 3409
  • Chip Points: 993
  • SSG Creator
    • View Profile
    • thatraymond.com
Re: Power supply suggestions
« Reply #9 on: June 30, 2021, 10:03:27 AM »
....and, on that note.


Here is another Matt, with the exact opposite experience. Hahaha!

I couldn't find a decent enclosure, so I happened to find this Kleenex Box randomly, so.... Yep. I stuck it in a Kleenex Box.

For now, at least.

That is fantastic!  Does it sound okay in that box?
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

TheBobbyElectric4

  • Chipper
  • *
  • Posts: 7
  • Chip Points: 1
    • View Profile
Re: Power supply suggestions
« Reply #10 on: July 15, 2021, 11:39:49 PM »
It does sound pretty great! Absolutely!

I'm searching for the Max. Gain .1uf cap...

But, I also have been trying to figure out how to get a dc jack in there, as I bought a 9-12v adjustable voltage wall wart today.

The other recently constructed guitar pedals that I've built, all have given me some clues as to where that power jack MIGHT squeeze in there.....??

BUT, I am definitely going to need someone to just tell me the answer, insteAD. Hahaaha!


PLeeeeeease Advise.....?

TheBobbyElectric4

  • Chipper
  • *
  • Posts: 7
  • Chip Points: 1
    • View Profile
Re: Power supply suggestions
« Reply #11 on: July 17, 2021, 05:47:49 PM »
Q: What about power supply?  What should I use?
A: Most little amps like this end up being powered by batteries, but any stable DC voltage supply ranging from 6v to 18v will work depending on what impedance you have hooked to it.  Recommended max voltage for 4 ohm will be 9v, max for 8 ohm is 14v, max for 16 ohm is 16v.


So, the Hosa branded adjustable voltage adapter that I bought, is the ACD-477. It's 3v-12v @1,200mA. I imagine, it'll be 110v, & 50/60hz, as well. As, I am in the Americas. It's been a while since calculating any input voltage impedences, but I can only assume that this is a pretty standard Power Supply.

I have to remember to ask for help with connecting a barrel input jack, as well. Are there points on the board, for maybe trading this, for the battery clip jack spots....?

Fingers crossed!

Please & Thank You!!!!!

phatt

  • Legendary
  • ******
  • Posts: 2204
  • Chip Points: 272
    • View Profile
Re: Power supply suggestions
« Reply #12 on: July 19, 2021, 07:15:50 AM »
As you have built pedals then most pedal schematics show how to wire up the external supply.
They normally use a switching socket so that when you insert an external supply it switches off the battery.
many stomp box forums have close up pics of the actual switch wiring.
Phil.

TheBobbyElectric4

  • Chipper
  • *
  • Posts: 7
  • Chip Points: 1
    • View Profile
Re: Power supply suggestions
« Reply #13 on: July 19, 2021, 01:05:45 PM »
Right on.

It's these details in certain facets of life, that somehow tend to escape me....

I just wasn't sure if there may have been something pre-designated on the board, for executing such a mod/addition.

Thank you!

joecool85

  • SSGuitar Admin
  • Legendary
  • ******
  • Posts: 3409
  • Chip Points: 993
  • SSG Creator
    • View Profile
    • thatraymond.com
Re: Power supply suggestions
« Reply #14 on: July 20, 2021, 10:26:25 AM »
Right on.

It's these details in certain facets of life, that somehow tend to escape me....

I just wasn't sure if there may have been something pre-designated on the board, for executing such a mod/addition.

Thank you!

Nothing on-board for this, just ground and positive input voltage.  Like Phil said, you would need to do this offboard like most pedals.
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com