And all wired up.. (actually most of the real work went on between this photo and the last, even though it looks like not very much has changed.)
Now for the "plug it in and hope nothing explodes" part...
An externally hosted image should be here but it was not working when we last tested it.
Now for the "plug it in and hope nothing explodes" part...
And ... it lives! Rails at |V+| + |V-| = 22.5 V, between 5-20 mV output offset.
That's all for today folks.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
That's all for today folks.
AndrewT said:
or... perhaps a 6 ohm, 80 dB/W/m surround monitor being used as desktop speakers...
Here, let me show you...
An externally hosted image should be here but it was not working when we last tested it.
Now, before you get all excited, let me just say it does work. I slightly underestimated the gain, it could use an extra 3-6 dB sometimes, but generally speaking it came out pretty much the way I expected...
P.S. the white box behind the telephone is the base station for the fiber optic cable from NTT. It's a 100 Mbps internet connection, 4 port gigabit router, and a digital landline all in one!
It can't be a waste if you are having fun, right?
- these are parts I've had kicking around for almost a decade. Better to use them like this than not at all.
- the amplifier has a useful purpose, connecting my Onkyo 24/192 soundcard to desktop speakers for casual, nearfield listening while being small, unobtrusive, and childproof.
- the LM3875 does a far more convincing job powering these little speakers than you seem to think.
I sometimes wonder whether you are just enjoying winding me up. Engaging me in the dialectical method, as it were.
Anyhow I'm going to listen some more. Just finished a very respectable Beethoven 5th, ... very respectable ... and I want to see what else it can surprise me with.
Give him a squad, see what he can do...
- these are parts I've had kicking around for almost a decade. Better to use them like this than not at all.
- the amplifier has a useful purpose, connecting my Onkyo 24/192 soundcard to desktop speakers for casual, nearfield listening while being small, unobtrusive, and childproof.
- the LM3875 does a far more convincing job powering these little speakers than you seem to think.
I sometimes wonder whether you are just enjoying winding me up. Engaging me in the dialectical method, as it were.
Anyhow I'm going to listen some more. Just finished a very respectable Beethoven 5th, ... very respectable ... and I want to see what else it can surprise me with.
Give him a squad, see what he can do...
A waste of what? A pair of 4-5 € ICs?AndrewT said:
I use a similar set-up at my PC in the office. It is absolutely okay for near-field listening at the levels you can use at a workplace without distracting yourself (and others). And 10mF per rail is absolutely sufficient for that application as well. When the amp starts to clip, it is already severely bothering others, who want to hold a conversation.
It's 1 mF, but either way, if there is no audible ripple on the output it's not a problem.
This is a low power amplifier with built in attenuation designed for a very specific application in mind. Emphasis on low power. The speakers get ugly when pushed even a little bit, so talk of clipping the amp is a purely academic exercise.
I imagine chip amps sound better with high sensitivity speakers because they sound better running at low power ... if so a small inefficient speaker at low volume = big efficient speaker at high volume.
Attached a revised Eagle schematic with updated resistance values for more gain, and an Excel worksheet for anyone who want to play with the design a little.
R1 10k
R2 680R
R3 680R
R4 1.2k (1k would be ok too)
R5 22k
This is a low power amplifier with built in attenuation designed for a very specific application in mind. Emphasis on low power. The speakers get ugly when pushed even a little bit, so talk of clipping the amp is a purely academic exercise.
I imagine chip amps sound better with high sensitivity speakers because they sound better running at low power ... if so a small inefficient speaker at low volume = big efficient speaker at high volume.
Attached a revised Eagle schematic with updated resistance values for more gain, and an Excel worksheet for anyone who want to play with the design a little.
R1 10k
R2 680R
R3 680R
R4 1.2k (1k would be ok too)
R5 22k
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