Something louder than a Ruby?

[gutsofgold]

I built a Ruby awhile back and feed it into a 6" 2w speaker. It sounds awesome, I love using the Neck pickup on my Les Paul and blasting the thing with all that bass. It gets all mushy and fuzzy and is a lot of fun. I didn't think it would be so fun and would like to get some more volume from it if possible. Is there another similar design that will get me some more output? I'm debating about building one of the submini tube amps but it might be a stretch for such a small speaker. So something in between a Ruby and a submini tube design?

[davidallancole]

You could build the Little Gem MkII from here:

http://www.runoffgroove.com/littlegem.html

or get a bigger, more efficient speaker.

[gutsofgold]

half the reason I like it is that tiny speaker. it's from an old radio. I love the sound just want a little more of it. I'll give that 1 watt Little Gem a chance.

[azrael]

Pump it up with more voltage.

What does the LM386 say on it? If it says N1, the max I would try is 12V. Higher rating means it can take more voltage.
You'll also want to make sure all the caps are rated accordingly.

[gutsofgold]

would higher voltage give me just more working headroom? or would it give me a volume boost as well?

[bdevlin]

There are 2 or 3 different version of the 386.  Some are slightly higher powered.  Buy the higher power chip and search the forum for a dual ruby (2 386's).

[gutsofgold]

thanks  I have a nice 12v dc adapter around here and I am going to "bassman" mod both the amps. I can't wait!

[frequencycentral]

Look out for a 386 N4, the highest rated. 18 volts and 1 whole watt of power.

[gutsofgold]

any audible difference between using a 386-N4 with 18v or two 386-N1's bridged at 9-12v

[Brymus]

If you look at the data sheets the LM386-4 is rated at 1 watt into 32ohms at 16V
If you look at the graphs you will see that at 16ohms and 16V its rated at 1.6 watts output power right at max dissapation.
SO its rated to 18V if that was plotted with a 16ohm load where do you think it would peak? Maybe 2watts? 1.8 at least Im guessing.
And I have tried it and compared and YES it is loudest at 18V
Also note that at 16V 16ohm load that at just past 1.2 watts it has 3% THD  VS 1 watt at 12V 16ohm load with 10%THD
Thats a pretty big difference in power and distortion by simply upping the power supply V .
So if it peaks past 1.6 watts at 16ohms with 18V Then you go LM386-4 (or NJM386BD ) X 2  at 18V
for BTL or a Little Gem MKII type circuit your looking at around 3 watts or more output.
I've tried this and its amazing for 2 little 8 pin DIP ICs it would push my 12" spkrs really well.
I'm sorry you said you want to keep your little spkr,I hope this helps you out anyway.
For comparison with the LM386-1 at 6V 8ohm load your getting less than 1/3 watt.

[Mark Hammer]

All the various ratings for the meagre little 386 assume that it enjoys no additional heat dissipation.  In other words, the power rating is based on the chip's ability to handle the heat generated by the required current all on its lonesome.  I haven't tried it, but I'm curious as to whether anyone out there might have tried milking the 386 for a bit more output by using some form of heat-sinking.

And yes, the suggestion of using a 386-4 is a good one.  I gather the -1, -2, or -4 ratings simply arise out of sorting batches of 386 chips for hardiness.

I've found a 386, powered by an octet of AAs, to be quite surprisingly loud.  Would the "leap" from 500mw to 1W or even, shudder, 1.5W make a big difference in loudness?  Not all that much, I suspect.  As always, I suggest to folks to have a nice "stiff" power supply (so consider an octet of C-cells, with a big smoothing cap), and an efficient cab/speaker combination, before assuming that they need to opt for more nominal wattage.  Six-inch speakers can be surprisingly loud if you situate them in optimal contexts, like a sealed-back ported cab.

[davidallancole]

I haven't pushed my LM386's much since I have two little babies under 1.5 years old, but does increasing the voltage make much of a difference?  

If you look at the chart called "Peak-to-Peak Output Voltage Swing vs Supply Voltage" you will notice above 10V with an 8 ohm load the voltage out settles to ~6.5Vp-p.  So it seems that if you increase the supply voltage above this, you are really just dissipating more heat in the chip.  Also from this you can infer that if you do a Bridge Tied Load (BTL) like the Little Gem MkII, you will not increase the power at all.  

To me it seems like the LM386N-4 chip will handle a higher voltage like 18V, but that you won't actually get more power into an 8 ohm load than if it is ran at 9-12V.

[petemoore]

  Yupp, they can sounds pretty good until louder takes the front seat and cleaner rides in back.
 The 2 chip model of course has more power.
 After that maybe look at the PS capability to drive more chips and consider dual-mono or stereo amp rig.

[Top Top]

Whoa... I may have to build that little gem mk II. I hadn't seen that.

Just trying to understand how that little gem MK II works... is what is happening that essentially one 386 is amplifying the regular output and the other is amplifying a phase inverted output, and each feeds to one side of the speaker?

I just built a Ruby and built it into an old wood box that I found in a basement of a house I used to live in - with a custom paint job of course, and a speaker that I salvaged from a toy. The "tone control" of the amp is set by how far you open the lid on the back of the box 

It would be cool to get just a little more clean volume, though it is definitely usable as is. I was thinking of looking for a more efficient speaker, as I tested it with an old car stereo speaker and it was definitely louder, but the speaker was torn. I think my speaker is 4"

[Brymus]

All the various ratings for the meagre little 386 assume that it enjoys no additional heat dissipation.  In other words, the power rating is based on the chip's ability to handle the heat generated by the required current all on its lonesome.  I haven't tried it, but I'm curious as to whether anyone out there might have tried milking the 386 for a bit more output by using some form of heat-sinking.

And yes, the suggestion of using a 386-4 is a good one.  I gather the -1, -2, or -4 ratings simply arise out of sorting batches of 386 chips for hardiness.

I've found a 386, powered by an octet of AAs, to be quite surprisingly loud.  Would the "leap" from 500mw to 1W or even, shudder, 1.5W make a big difference in loudness?  Not all that much, I suspect.  As always, I suggest to folks to have a nice "stiff" power supply (so consider an octet of C-cells, with a big smoothing cap), and an efficient cab/speaker combination, before assuming that they need to opt for more nominal wattage.  Six-inch speakers can be surprisingly loud if you situate them in optimal contexts, like a sealed-back ported cab.

I tried heat sinking them (using the SIP package-NJM386BL) and I use 12 AA batteries and 2200uf + .01 filter cap.
BTL at 18V the NJM386BD was loud enough through a 98db SPL spkr to have my friend play the drums and we could still hear each other,
Granted he was playing lightly not heavy handed but it was still THAT loud.
And it was fairly clean not all distorted like with the gain at pins 1-8 turned up.

Also for (in the words of Tim Taylor) "More Power" you could parallel the two phases with more chips.
SO you would have 4 386 chips in a PP BTL set up I havent tried this yet though. = 6 watts total 
I plan to soon as I finish what I am working on now.

[Mark Hammer]

Well there you go!! 

[drk]

i think an upgrade on the cab/speaker would do much more results than going from 0.5 watt to 2watt.

[ItZaLLgOOd]

What about an LM380?

[Mark Hammer]

I made this one - http://hammer.ampage.org/files/Miniamp.png - using an LM380, and it can get pretty loud.  I have it in a closed particle-board cab ("sealed" would suggest my carpentry skills are better than they are), power it with 8 D-cells, and use it to drive a 6.5" Marsland Pacer speaker.  I made another one in a much nicer cab, with an 8" speaker, using the same power-amp section but a Doug Hammond Meteor for the front end, and it also gets pretty dang loud.

[brett]

Hi

but I'm curious as to whether anyone out there might have tried milking the 386 for a bit more output by using some form of heat-sinking

My 2 c worth says that I can't imagine that the 386 has voltage-limited components in it.  It probably just fails when the silicon slab gets too hot and it gets into thermal runaway.  I've seen people stick aluminium foil to the ICs for cheap heatsinks.  Use a *thin* film of glue. I reckon it would work quite well.

cheers