Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: R3van on June 30, 2021, 05:07:50 am
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Hello everyone I have a cheap 5 watt solid state amp and I'd like to build a new amp into the chassis, I have checked out the "little gem" schematic by runoffgroove.com however it operates at a mere 1/2w, considering it's only a couple capacitors and resistors I was wondering if anyone would know how to replace these componants to draw more wattage from the 9vDC cell, I'd like it to be mean and loud but considering amp hours on the 9v any 20w circuit or higher would be sufficient, I would require roughly 1-2 hours play time for busking as far as amp hours on the 9v cell, I only wire guitar circuitry and have no experience in amp building.
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You can build a little audio amp with a 9V battery power supply, but I highly doubt you’d get 20W output.
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here's one of my SS dirt road adventures;
Sans Tubes (el34world.com) (https://el34world.com/Forum/index.php?topic=24695.0)
what the "hype" says and what the scope reads makes great fodder for thought.
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You can build a little audio amp with a 9V battery power supply, but I highly doubt you’d get 20W output.
Mm, fair enough.
As per the schematic the "little gem" amp can take 12vDC so there's plenty of larger battery options, I just wonder how to make the circuit higher wattage at this point, I mean it's only like 4 capacitors and a resistor, I think that resistor value plays part in current draw but that's the full extent of my knowledge.. I might put the schematic on fiverr.com but first I'll test it at 1/2 watt with 9v through a decent speaker to hear the tone.
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...I mean it's only like 4 capacitors and a resistor,...
AND a "8-DIP socket". What goes in that socket? Maybe it matters?
I mean, 4 caps and a resistor alone can't be an amplifier, can't make sound bigger.
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i don't have the specific TDA chip numbers but there are some ready-made boards you can get off of ebay for about five bucks shipped if you're willing to wait for overseas shipping. i haven't used off battery but 12v 1a supply sounded reasonably loud
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Around 10 or 15 years ago I spent a fair amount of time messing around with circuits like this.
I think this “Little Gem” is a variant on the “Lil Smokey” battery amps that were initially sold stuffed into cigarette packs, before the company switched over to selling them in cig pack sized plastic cases. Remember those? One schematic:
http://farm5.static.flickr.com/4032/4267267797_792fb8ee10_o.gif
That amp used an LM386 chip or variant, and yes, a 9-volt battery, to put out something in the half- to one-watt range through a little plastic (mylar?) speaker housed in the same tiny package. Cheesy, but gritty and fun - enough to scare the folkies at a campfire with some Sabbath riffs, anyway.
The plastic case version had a speaker jack, and most reviews you found on the web of those Smokey amps included a line or two about how awesome and surprisingly loud that little 1-watt amp sounded through a 4x12 speaker cabinet.
I think in your case, there is wisdom to be found there.
If you play a 1 watt amp through a highly efficient 12 inch speaker, and can tolerate some amount of overdrive, or even something similar to “soft clipping” present in most pop guitar sounds, you might have something loud enough for busking. I cannot emphasize this enough: an efficient speaker makes a really, really big difference in how loud an amp sounds. A 5 watt amp through a small, inefficient speaker can absolutely sound much quieter than a 1 watt amp through an efficient speaker. This makes sense to people when you say it, but then they forget it and focus only on how many watts the amp is rated for. That’s a mistake if you’re going for volume.
Making a 12-volt pack out of eight AA batteries will let you run an LM386 based amp notably longer than a single 9 volt battery, and will give you a little more volume and headroom - maybe even enough more to notice. You can buy an eight-pack battery holder for AA batteries - check on Amazon or use your google machine for options.
My advice, for what it’s worth: If you must have something in the 10-20 watt range, or you must have crystal-clear clean tones, you should buy a ready-made battery amp. They are available for purchase. But if you want to build something and are ok with some grit in your tones, build that Little Gem and try it through an efficient 12” guitar speaker to see if it seems loud enough for your purposes.
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other thing to look into for power is Li-ion cells, they've gotten REALLY good (i have a rotary hammer and a sawzall that run off battery packs and they're plenty powerful and long lasting)
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Around 10 or 15 years ago I spent a fair amount of time messing around with circuits like this.
I think this “Little Gem” is a variant on the “Lil Smokey” battery amps that were initially sold stuffed into cigarette packs, before the company switched over to selling them in cig pack sized plastic cases. Remember those? One schematic:
http://farm5.static.flickr.com/4032/4267267797_792fb8ee10_o.gif
That amp used an LM386 chip or variant, and yes, a 9-volt battery, to put out something in the half- to one-watt range through a little plastic (mylar?) speaker housed in the same tiny package. Cheesy, but gritty and fun - enough to scare the folkies at a campfire with some Sabbath riffs, anyway.
The plastic case version had a speaker jack, and most reviews you found on the web of those Smokey amps included a line or two about how awesome and surprisingly loud that little 1-watt amp sounded through a 4x12 speaker cabinet.
I think in your case, there is wisdom to be found there.
If you play a 1 watt amp through a highly efficient 12 inch speaker, and can tolerate some amount of overdrive, or even something similar to “soft clipping” present in most pop guitar sounds, you might have something loud enough for busking. I cannot emphasize this enough: an efficient speaker makes a really, really big difference in how loud an amp sounds. A 5 watt amp through a small, inefficient speaker can absolutely sound much quieter than a 1 watt amp through an efficient speaker. This makes sense to people when you say it, but then they forget it and focus only on how many watts the amp is rated for. That’s a mistake if you’re going for volume.
Making a 12-volt pack out of eight AA batteries will let you run an LM386 based amp notably longer than a single 9 volt battery, and will give you a little more volume and headroom - maybe even enough more to notice. You can buy an eight-pack battery holder for AA batteries - check on Amazon or use your google machine for options.
My advice, for what it’s worth: If you must have something in the 10-20 watt range, or you must have crystal-clear clean tones, you should buy a ready-made battery amp. They are available for purchase. But if you want to build something and are ok with some grit in your tones, build that Little Gem and try it through an efficient 12” guitar speaker to see if it seems loud enough for your purposes.
I already have a good little 10w busking amp that takes 10xAA's and I have a 5w busking amp that takes 9v, considering the engineering of said products 5w is probably the most a 9v can reasonably do so I might get a larger diameter/efficiency speaker for it as it has a raunchy blackface tone so it'd probably kick arse, as you said the marshall cab/9v thing is a thing.
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The ROG amp is a fun little thing, but no circuit change will give you more power. The ebay chip amps are usually in the 50-100 watt range. The chips they use can make good hifi amps (look up gainclone) and are perfectly usable for guitar power amps (fender gdec/bdec), but you won't be powering them with a small battery (pack).