Quote from: J M Fahey on May 29, 2016, 06:48:11 AM
You can't reduce gain very much, I guess minimum is around 20X , because it becomes unstable.
So reduce R2/R1 ratio to about 20:1 but not less, any ectra reduction myst be input padding."Which is not all bad, you can add a passive tone conrol which will be lossy anyway.

OK here is plan B. I've been playing around with the Lm386 opamp and decided it might suit my little enclosure better than the TDA2003. I thought id use 2 of the TDA2003 modules with each one driving a 4" car  speaker in some sort of cabinet. Maybe shaped like the Roland Street Cube https://m.thomann.de/ie/roland_cube_street_bk.htm

Sent from my SM-G935F using Tapatalk

Lots of stuff is USB chargeable these days. Is it feasible or safe to build in USB charging to a diy amp or other builds?

Sent from my SM-G935F using Tapatalk

Quote from: phatt on November 15, 2017, 06:47:36 AM
You can always insert a pot before the transmitter to wipe off some voltage.
Agree with Joe,,,,,Cool Idea

Yes great idea on the pot.
What I like is that I can play my electric travel guitar in anyones house, boat, car, caravan... as long as they have an FM radio. Lucky them!

Sent from my SM-G935F using Tapatalk

Thanks. My first attempt at guitar amplification was trying to connect a soundhole pickup on my acoustic into the 'hifi' in my photo. Didn't really work, maybe better impedance matching would work but I was afraid of frying the hifi.

A few steps on I made a TDA2003-based amp, it's OK but clips rather harshly. Then someone gave me the headphone amp, I had the transmitter for playing MP3s in the car, one thing lead to another and this was the result. Hey, I can now play my Hofner Shorty in the car!

The amp has 'off', 'c' (clean) and 'd'  (dirty) settings. There is basically no clean sound because the amp causes the transmitter to clip even on 'c'. The 'd' just goes to cheap and nasty distortion which I kind of like. Vox make some headphone amps designed t emulate classic amps such as the AC30....

Probably been done before but...
Headphone amp + fm mps transmitter +  any FM Radio = wireless guitar amp

Works well with my Technics HiFi. Using a better headphone amp (eg Vox.ones) and transmitter might improve matters. Need to keep amp volume low to stop the transmitter clipping. Little chance of hurting the receiver as the FM signal is weak enough. Plus the neighbours can hear  my killer riffs if they tune in to
106.7 FM

Sent from my SM-G935F using Tapatalk

Any suggestions for preamp design?

Mackayprod, thats cool. Are you using the Velleman kit, or just the TDA2003 chip which is at the heart of it? I got kit from Maplins (the UK/Ireland equivalent of Radio Shack)

Been playing with it again and decided I like it (or am too lazy to modify). basically I play it quiet or else flat out (wakes the family if not the neighbours) and theres no in-between. One mod I heard of is to use a smaller resistor going in to the inverting input. this increases negative feedback thus reducing the gain. I based the enclosure design on the Pignose (imitation, flattery and all that) though its a bit smaller. I put a bit of effort to fit a DC input jack and also a headphone out jack, so I can always change the guts while keeping the enclosure (of which I'm quite proud). Mainly used with my homemade Lap Steel and a Hofner Shorty guitar. Actually sounds great as a Harmonica amp too.


Letting the battery run down gives more distortion anyway (sometimes in a good way...) as Brian May did with his Deacy amp. You can now buy a Deacy replica including a variable power supply to simulate a dying battery but wheres the fun in that?

Think iIl just accept that i can have quiet and clean or loud and dirty.  For quiet and dirty i can use my overdrive pedal. Will be back for more ideas on my next build-possibly something tiny with a 2" speaker just for fun.

Thanks for that. It can take up to 18 v so will look for a new supply ti deliver that. Or 12 AA batteries. Would a 4 ohm speaker help?

]I built one of these into a practice amp
http://www.vellemanusa.com/downloads/0/illustrated/illustrated_assembly_manual_k4001.pdf
Its powered by a 9v battery or a 12v power supply, in a 6"x9"x5" enclosure with a 4" 6W 8ohm speaker.

Any ideas on getting a bit of clean headroom on it? it goes into gritty overdrive pretty quickly. I do like that but would like more clean if possible.
https://sqtu8a-sn3301.files.1drv.com/y3mal6r6dsV_fjgpC0VUxSw0Psb_ZCn2i4Gixu6pstBdmNprn8RNGNiUe3FvJcmTDoXdS1Cx1QXDuZAaWfA_sCQPYgMXS5DppEbXR4tuaQQN3_JNCSJf7d57tuj5Xo5cTMcnoPv1IeESIn7MuLkIdT-bK98yhFXOGCykALazlgHDn0?width=2322&height=4128&cropmode=nonehttps://s6tu8a-sn3301.files.1drv.com/y3mkd0BFs-OuSa0LQgNjSnTqj8EA-jinsUa6s6kUS6G38yEb1qFesbTImImHYdnFbmTQieIGLcQEE_BNVpWYZP6qiRHwhpNTIPK7KViepoycbzcNT9cLwodHwzcN3dcevMIEMESy5ei4rWwMEiAtSjCOhh8JRA3lyzLDLKHcqsrlLU?width=2322&height=4128&cropmode=none