As you see it shares with the Ruby the same topology: a buffer and a chip amp. It uses a JFET buffer with a MPF102 and the 1W TDA7052 chip. It is a clean amp and it reacts very well with any pedal in front of it. I don't use a lot of distortion so this little amp suits all my needs. It doesn't have a volume and tone control because I wanted a plug-in-and-play amp. If you want an amp with a volume control try the TDA7052A, it has a volume voltage control pin that works perfectly (simple pot), this chip has the advantage that the volume pot is not on the signal path.
Of course the PUNCH also works with batteries, a 9v battery or with six 1.5V batteries in series. For small voltages and currents the sound could become distorted or to muddy, if so decrease the 1u cap to 470n or smaller.
What about the speaker? The guys from ROG say
What speakers do you recommend for use with your mini-amp circuits? While the Ruby, Little Gem, and Little Gem MkII practice amps can be used with any speakers, best results are achieved with full-size speakers intended for use with guitar amps. The amps will work well with an total impedance of 4, 8, or 16 ohms. We've tried hi-fi speakers, clock-radio speakers, and auto speakers - they just can't cut it. For me, using anything other than a speaker designed for the frequencies of an electric guitar produced sounds more like a toy than an actual amp. However, you may want to ask at Aron's Stompbox Forum. Many of the members have built one of the aforementioned amps and may be able to suggest a decent-sounding small speaker.
This is only in part true. One thing they are right is that clock-radio speakers and small radio speakers won't work! But the same is not true for hi-fi speakers and auto speakers. Let me be more precise about it.
I've tested the PUNCH and the Ruby with some 6'' auto speakers and they work great, specially with the PUNCH. This Fonestar UT528 speaker of 5.25''=13.3cm with a frequency response of 50-12.000 Hz and a sensitivity of 90 dB - 1 W/1 m works great.
I've also test it with a smaller one, the Fonestar 3''=7.5cm speaker (20-14.000 Hz, 8 Ω, 89 dB - 1 W/1 m)
and also has a great sound.
Here is the PCB pdf file.
Here is a cabinet for the PUNCH with a 3'' Fonestar speaker and using a IKEA wooden box. The rear photo shows the 9V battery enclosure.
As always comments, questions or suggestions to my email.Palavras chave/keywords: guitar, amplifier, 1W, DIY
Última actualização/Last updated: 23-01-2017 [09:19]
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