Yes, it is true that the MicroCube's sound is mostly buried in the proprietary processing. I just want to modify mine with a Class-D amp (TDA7292), a LiOn battery, and a better speaker (Eminence 620H) to get more usable power. I'm thinking I can figure out the wiring from the other Cube schematics that bucks provided; but I'd still like to see the MicroCube's schematic.
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The KEY to using ANY Class-D power amplifier is to NEVER NEVER EVER let it go into clipping! Class-D clipping is the most horrendous sound; much worse than any Class A or AB clipping. Put some sort of limiter in front of Class-D---even a pair of anti-parallel signal diodes would be an improvement---to avoid this.
Or just take the Roger Sanders (Innersound, Magtech, Sanders Sound Systems) approach and just use a suitable High-Power Class D amp so that you could never reach clipping before your ears give out.
After all, isn't the cost / size difference between low and high power Class D negligible? Is "Low Power Class D" just straw dog?
After all, isn't the cost / size difference between low and high power Class D negligible? Is "Low Power Class D" just straw dog?
Hey John,
I was thinking doing the same thing actually. I don't have experience with solid state stuff, so I'd appreciate some details on your build. I noticed many JC players just use the clean side (CH1) because of the noticeable differences between the two channels and they don't like CH2. It might be superficial but I was thinking maybe 2 clean channels pre and a 2 channels power amp could be fun for wet/dry or stereo purposes. If you have documentation I'd appreciate the intel
Many thanks!
Nah I live near the Black Gate of Mordor... Hungary
(Sorry, bad joke)
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Hi john65b. When you say to remove the third 2sk117, is it just the transistor or all components between r13 and c10 ? Thanks.
I mean only Q3 as such or all components connected to it between r13 and c10 (resistors/capacitors etc) as well?
In Class D the sinus signal is transformed into a square wave signal (because in a such case transistors are working in short-circuit or are blocked. In both cases, the power is almost null p=VxI, first case V=0 and in second case I=0) --> at the end of signal path, just before the speaker, a low pass filter is added to have the amplified sinus signal. So in the signal path of class D the signal is very transformed and can be considered as "digital" (a square wave is only "0" and "1"). The low pass filter can't be ideal so you never had a very clean signal in the speaker. Class D has been designed for low cost amplifiers in headphone, cars, battery powered applications... not for Hi-fi and not for instrument amplifiers. Class A-B has an efficiency of 78% max and class D is about 90%. Not a very big difference in an instrument amplifier except if you want a small amp powered by a battery but sound is not good. You have to choose
Best sound is achieved with a tube in class A (I have a mesa boogie Express 25 where you can switch between class A-B and A and class A has a very warm sound. I love it).
Yes, all the home theatre systems are making people's ears bleed from all the dirty signals. Maybe the extra bandwidth to 20 kHz masks the artifacts the filters leave in? Maybe convert these poor souls so that they can once again hear the song of angel's.In Class D the sinus signal is transformed into a square wave signal (because in a such case transistors are working in short-circuit or are blocked. In both cases, the power is almost null p=VxI, first case V=0 and in second case I=0) --> at the end of signal path, just before the speaker, a low pass filter is added to have the amplified sinus signal. So in the signal path of class D the signal is very transformed and can be considered as "digital" (a square wave is only "0" and "1"). The low pass filter can't be ideal so you never had a very clean signal in the speaker. Class D has been designed for low cost amplifiers in headphone, cars, battery powered applications... not for Hi-fi and not for instrument amplifiers. Class A-B has an efficiency of 78% max and class D is about 90%. Not a very big difference in an instrument amplifier except if you want a small amp powered by a battery but sound is not good. You have to choose
Best sound is achieved with a tube in class A (I have a mesa boogie Express 25 where you can switch between class A-B and A and class A has a very warm sound. I love it).
https://www.diyaudio.com/community/forums/class-d.49/
To have the original, yous shall keep only the fundamental fo. It is physically impossible except if you have an ideal filter. Of course, with a good filter (at least order 2) you can reduced all these extra frequencies (2f, 3f, ...) to an acceptable level for ears ... this is the reason why the THD of class D amplifiers can be very low BUT you will never had a pure signal as other classes. This is ONLY your choice. For me only advantage of class D is for battery powered application OR for a very power amplifer in a small form factor (cars, in case where you need to move with the amplifier, ...). For DIY AND for instrument amplifier, a class AB is very a good choice and class A is the top !
Just skeptical as more demanding applications do not have people running for the door. If the amp is not allowed to clip I doubt many would know the difference. Quilter Labs is one company that uses SS parts in the preamp and Class D amp out back and people seem to like them.