DIY 8 Watt Portable Guitar Amp

[NapoleonDK]

...must be rated in sum kinda chinese watts...

My dad used to refer to that as RMS watts versus ILS watts. ILS meaning "If Lightning Strikes".

 

[shanx]

I think we all get into a bit a bit of ''life gets in the way'', ask Tubelab. He has been through h*** of a lot lately and thankfully still takes some time to give good advice. Enjoy the summer while it is still here!

1600 watts: sure that is fine if you have any hearing left while the subs are blowin the trunk off your ride. As for THD well let's throw that out the window as well.Thanks to arcticbreaze for confirming suspicious claims of car audio. I want an amp that goes to ELEVEN. not ten

 

[Tubelab_com]

if any one is lookin for shallow speakers for in a guitar......Take a look at the Faital 3 and 4 inch drivers.

I looked at the Faital web site and decided on a 4FE32, but it seems that there are none to be found in the US. There is a Faital distributor about 10 miles from here, but they don't stock anything. They could get me the 4FE32, but I had to buy 8 of them and wait for 30 to 90 days.

I found a seller in the US that had a 4FE30 which isn't on the Faital web site. The price was a bit steep, and they charged me $17 to ship a 10 ounce speaker via UPS ground.

I must say that it is under 2 inches, very light, and quite loud. It sounds pretty good fed by a 2 watt tube amp while mounted to a piece of cardboard.

Are there easier ways to get more power out of 12 volts? How do cars get thousands of watts?........I also hav put my 1600 watt car amp onto my heathkit watt metter and they must be rated in sum kinda chinese watts coz its only about 50 watts per channel.

There is lots of junk sold as a 1.21 jiggowatt car stereo amp. There are real 1000 watt amps and the last time I looked the SPL record for "car audio" was over 150db. These competion cars are not street drivable since most of the engine power is used for auxilary alternators.

There are genuine high power car audio installations. Depending on the power level, one or two auxiliary alternators and batteries are used. The power cables are usually made with welding cables since a 1000 watt amplifier will draw about 120 amps at full crank.

I personally made a car stereo amp for my senior project in college. It was 20 years ago and I was 40 years old. Todays 200 amp mosfets did not exist 20 years ago, but I still made about 320 total RMS watts. The amplifiers were all pretty standard stuff. There was a 120 watt amp for the 15 inch sub, a pair of 60 watts amps for the 8 inch speakers and a pair of 40 watt amps for the 6 inch coaxials in the front doors. The power supply is where the magic happens. A controller chip (SG3525) controls a few big mosfets which chop up the 12 volts DC into AC and feed it to a step up transformer. So the car's single 12 volt supply becomes a +/- 80 volt supply which will run a big solid stste amp.

I recently discovered a chip that turns 12 volts into any voltage from 200 to 500 volts at up to 40 watts, so a little battery powered tube amp is a posibility. I have been testing several tubes that have the lowest heater power requirements to see which ones can give me the most efficient 3 to 5 watts of tube audio.

 

[Passinwind]

I looked at the Faital web site and decided on a 4FE32, but it seems that there are none to be found in the US. There is a Faital distributor about 10 miles from here, but they don't stock anything. They could get me the 4FE32, but I had to buy 8 of them and wait for 30 to 90 days.

I found a seller in the US that had a 4FE30 which isn't on the Faital web site. The price was a bit steep, and they charged me $17 to ship a 10 ounce speaker via UPS ground.

I must say that it is under 2 inches, very light, and quite loud. It sounds pretty good fed by a 2 watt tube amp while mounted to a piece of cardboard.

I went through TSG Audio in Utah, who stock the 4FE30 and were very reasonable on price and shipping. I bought a pair for some back firing tweeter experiments on one of my DIY bass cab builds. I also started by testing them in the little cardboard boxes they came in.

 

[razorrick1293]

"chinese watts" i love that!

Audio power - Wikipedia, the free encyclopedia

quick google search found this which may explain something

 

[Tubelab_com]

Enjoy the summer while it is still here!

In your end of the continent, summer is a good but short thing. Here it means 4 months of rain, 95 degree heat and high humidity, heat index 105+. It's too hot to drag the table saw outside and make cabinets. We need winter for that. Winter here is 2 months of "absence of extreme heat" with 0 to 10 days of temps below 50 degrees.

I went through TSG Audio in Utah

I found several web sites related to that name, none of them were in Utah. I found an Ebay seller in Utah selling Faital speakers, but none of the 4 inchers. It doesn't matter now, unless I make something that I like well enough to want more.

"chinese watts" i love that!

My Chinese computer speakers must be rated in Chinese watts. They run from a 12 volt 2 amp wall wart, yet deliver "600 Watts" all through a pair of 2 inch satellites and a 5 inch sub.

Before I came to work here I ran the service department of an Olson Electronics store (like a Radio Shack). We had all sorts of inflated ratings, but the best was a plastic POS Symphonic stereo that claimed 72 watts PMPO. No matter how I tested it I got about 1.5 WPC. Even dead shorted output current times open circuited output voltage, netted maybe 3 WPC.

As for the amp...

My current experiments are related to seeing how much power I can squeeze out of all the little tubes that draw low heater current. All power measurements are real RMS watts at 5% distortion measured on an HP8903A, which was made and calibrated in the USA. The number will be less than 5 to avoid sucking the battery into a black hole. I am also testing some subminiature tubes for preamp use.

 

[shanx]

Keeping in mind those class D amps which get really efficient, still can't create power from more than what is going in through the power supply, or maybe they refer to ''instantaneous'' watts from the capacitor bank..but not continuous. If tubelab even gets close(which he will) to 5 real watts that is super for a portable tube amp.

 

[Tubelab_com]

If tubelab even gets close(which he will) to 5 real watts

So far I'm stuck at 2 watts, primarilly due to repurposed tiny OPT's that get lossy as you increase power. 2 watts may be enough though inside the guitar.

Bigger power would not be an issue in a physically bigger amp. 10 watts in a battery powered combo the size of a Fender Champ (in fact it will likely go into a dead Fender Frontman's cabinet) is very doable. Power comes from a 22 volt 5.5 AH LIPO battery that weighs less that 1 pound. Run time over 3 hours (1.5 amps draw at full crank).

Tube lineup 6AK6 input amp (may change this due to microphonics, need 150 mA heater), 12AX7 gain stages, mosfet PI, with a pair of 6AQ5's for output in P-P with an Edcor OPT. The output stage is switchable from true P-P to quasi SE (ground one grid, disconnect cathode bypass cap) for low power.

Yes, I have it mostly breadboarded, but I am still working on the power supply. SMPS for heater, SMPS for B+ (260 V).

 

[NapoleonDK]

I put up a video of my progress. Probably not very interesting to the uber-talented and ever-smart wizards that populate this forum.

DIY Guitar Amp Part 1 - YouTube

The motorcycle parts arrived safe and sound. I should be able to resume work on this project as soon as I'm done with a few of my other ones.

 

[NapoleonDK]

UPDATE - I got distracted.

Well, it turns out the motorcycle snapped a bearing housing in the rear hub, knocking the hub out of alignment, which caused the premature wear on the drive collar thing. My bike is still out of service. =\

I wanted a quick fix for my guitar amp, so I bought myself an iRig for $14.99. Plugged into the iPhone, it gives me a bunch of neat effects/settings/amp models to play with. It also seems to have a much more appropriate output impedance to match the input of my TDA2003 chipamp.

Plugging the iRig into the portable guitar amp has given me more to think about, and I've decided this amp still doesn't have the output volume I'm looking for. I need to learn more about DC power supplies, and I need to get better at soldering.

I have put at least 6 hours on the amp now and still haven't charged the battery, but it's HEAVY and awkward with the giant battery in the back of an otherwise emptyish box. The next generation guitar amp will have to use Li-ion battery packs.

Otherwise, I've been working on guitars. Today I'll be soldering back together the gutted interior of an Ibanez bass with active pickups after it received a swirl dip paint effect.

Anyone who can point me towards a reasonable solution to get 50-60 watts out of 12VDC shall be considered by myself to be a wizard. Of course if I can get a line on some Li-ion batteries that will give me 24-36VDC, then my options really open up!

 

[Tubelab_com]

I can get a line on some Li-ion batteries that will give me 24-36VDC, then my options really open up!

I am using this in my portable "amp" which contains a tube amp and a small PC for all sorts of modelling software type effects. It's far from finished as are most of my projects. 22.2 volts 5000 mAH

Sky Lipo 5000mAh 22.2V 20C

I use this inside the guitar for a low powered tube amp and some basic effects. most sube circuits are functioning, the wood work is lagging behind....I tossed the last body in the trash and took a break. I start on a new one tonight. I am currently experimenting with a pickup per string,,both piezo and magnetic.

SKY LIPO 5000mAh 20C 11.1V Hardcase Lipo battery pack

11.1 volts 5000 mAH.

Understand the risks involved with LIPO batteries before using these. They WILL catch FIRE if abused. Use the proper charger, and do not discharge below the minimum voltage, and do not physically abuse the cells. some type of safety circuit is needed if you wire these things in series.

I bought a dedicated charger made for these cells that runs from auto or house power, and I use the hard cased batteries in the guitar since it could be dropped. My devices will shut off before minimum voltage is reached. The guitar will have a second battery with auto switch.

 

[razorrick1293]

Anyone who can point me towards a reasonable solution to get 50-60 watts out of 12VDC

a fly back converter can do that,

Switching Converter Power Supply Calculator

that should be a calculator for finding component alues and give you an idea of peak input current,

They're quite simple, and theres plenty of diagrams around.