Beginner's Gainclone, HiFi LM1875, The Amplifier Board

[JMFahey]

Yes, check the options.
And datasheet examples, specially in chipamps, work quite well.
Can be improved, of course (the whole of DIYaudio is specifically dedicated to such tasks ), but are not a bad point to start, at all.
Just curious about the 12V limitation: is is a car/boat installation or similar?

[danielwritesbac]

Originally Posted by mortron

So at 12v, is it reasonable to expect 5-10 watts?

Yes, I guess you'd want to use the 12vdc Gainclone thread for that.

[mortron]

I am trying to assemble an "off the grid" hi-fi for the cottage as we are on solar and minimal electricity from a generator when real juice is needed, but I will probably just use some 12V SLA batteries to run an amp.

[JMFahey]

"off the grid"

Mmmmhhh, interesting.
In that case squeeze every single drop of energy.
A single TDA2003, run straight from a 12V SLA Battery, provides enough power to enjoy music, with minimal requirements.
No, not *loud* but enjoyable, about what a TV plugged into a Hi Fi cabinet can give.
Same amp bridged, provides 16W into 4 ohms or around 10W into 8, not bad.
I suggest you build one, get a kit somewhere, and actually test it.
You may be surprised.
And if not enough, I think you'll need to get some car type amp, with built in switching converters to get higher rail voltages, because with only 12V, the limits are those stated earlier.
But first build a simple kit and try it.
There are more modern chips, even Class D, of course. But 12V is 12V.

[tommy_o]

Class D would be more efficient, right? You can get a $15 amp board assembled and delivered based on TA2024 that would work. They sound decent, play reasonably high volumes, run off of almost no power. I think mine is running on a pretty minimal 12v wallwart originally from a wireless router, driving my Mark Audio full range bookshelf speakers (6 ohms, I believe). Search ebay for 'ta2024' and Google search for 'tripath sla battery' for more context.

[danielwritesbac]

To have the best of both, you can use Bi-Amp this way:
TA2024 to run a high efficiency, 91db or better woofer, and a passive crossover.
Made for portable Class AB chip to run the tweeter.
In this case, when the bass amp clips, the tweeter does not.

When your battery runs down, you'll get some crunchy bass, but your treble will stay clean.

[JMFahey]

Excellent idea.
Couldn'ty agree more.
So much so, that I have been using it in a ton or my "Callejero" (Street Musician) Amps:
Bridged TDA2005 into an 8" or 10" woofer plus biamped TDA2003 into a 4 ohm LeSon Tweeter.
Loud and clean !!
The cabinet includes an SLA 12V 7AH battery and the intelligent charger:


The unmarked knob between both channels is an extra volume/attenuator for the high frequency amp.
The LeSon tweeter is very loud and can be overpowering.

[danielwritesbac]

Those look excellent!

Although this does happen to be an LM1875 thread, I do appreciate the discussion of Bi-Amping for low power amplifiers--It is nice when the tweeters don't play any clipping.

[dimkasta]

Hello Dan
I have been reading for a while now about the LM1875s and they sound as a nice prospect for my next project.
My concern is that my speakers (Montana EP Signature) are 4ohms and 92db (based on the EPS2 specs that I expect to be similar).
I was thinking to remove the bridges (which I would expect to make them easier to drive?) and biamp them (4 monos for 2 speakers).
Do you have any suggestions?
Should I look for a parallel arrangement instead?
Thanks in advance

[danielwritesbac]

Originally Posted by dimkasta

My concern is that my speakers. . . are 4ohms. . .
Should I look for a parallel arrangement. . .?

Yes, you should consider making a parallel amp when driving 4 ohm speakers.

Solo chip amp will probably distort or break, probably distort for a while and then break later. So, you should use parallel chip amp instead.