Chipamps - cheap, high quality hi-fi amplifiers

Wizard

There is an amplifier called a GainCard which sells for $1,850. (Was about $3,300 when it first came out many years ago)
And it created sound quality that blew the world away
http://www.sakurasystems.com/price.html

Then ... someone looked under the hood ... and found that the amplifier had a chip (LM3875) and a really small number of other components.

So ... you can buy these in kit form now:
http://www.audiosector.com/lm3875.shtml

Cost is $64 plus cost of transformers & chassis & bits.

So ... I've ordered one.
Let's see what happens. ?

Wizard

Ordered one and the kit has arrived.
Time to start assembling amplifiers.

On gumtree found a pair of AR18LS loudspeakers for only 600 ront, so decided these would be matched with the to-be-built amplifier.

singemonkey

I reckon it just won't have that certain something... that mojo that a GainCard amp would have. Amirite fellas? ?

Reinhard

Let us know how it sounds ?

singemonkey

Didn't mean to derail you thread. Couldn't resist.

I'd be interested in seeing what the build looks like Wizard. I've started to become very dissatisfied with my system for listening to music and have had a decent hi-fi amp on the agenda for a long time. For example, there's this tiny jazz club here in Observatory where you literally can't tell when you walk by whether you're hearing the sound system or a live act (it could be either with them). When you're in there and they're playing music over the system, it fills the whole place while remaining crystal clear. That's an old system.

My Dad likewise has a NAD amp going into speakers that were pretty hot-stuff when he bought them in the early '70s. Again, the room fills. With my system the sound is always directional - you are always aware of the source even when the volume's cranked.

Anyway, blah blah. Point is, a reasonably priced build of a top quality amp would be a great way to move forward. Keen to see the process.

Psean

Build pics would be great ?

nick

Pics!

AlanRatcliffe

Looks real interesting Wiz. That's two channels, right?

Hmm... I wonder... Could you stack six channels of these for 5.1?

Wizard

Alan Ratcliffe wrote: Looks real interesting Wiz. That's two channels, right?

Yup.
Two independent amplifiers; but will share a transformer.

I will post pics of the build.
I've found that the discipline & expectation of progress is a great incentive to finish.

nick

Does it come with the casing etc?

Wizard

nick wrote: Does it come with the casing etc?

Nope. Bare bones.
The kit includes PCB's; amplifier chips & supporting resistors; capacitors & rectifier diodes.
I need to source transformer; heatsinks; chassis; connectors & volume potentiometer; ...

Will probably take a while as I ponder different options for the chassis.

Psean

Wizard wrote:
nick wrote: Does it come with the casing etc?
Nope. Bare bones.
The kit includes PCB's; amplifier chips & supporting resistors; capacitors & rectifier diodes.
I need to source transformer; heatsinks; chassis; connectors & volume potentiometer; ...

Will probably take a while as I ponder different options for the chassis.

I like the aluminium U-channel idead in the pdf on the audiosector site - a chassis that functions as a heatsink too. The aluminium and wood on the Patek Amps on there look really cool too.

Wizard

Psean wrote: I like the aluminium U-channel idead in the pdf on the audiosector site - a chassis that functions as a heatsink too. The aluminium and wood on the Patek Amps on there look really cool too.

+1 !!

makepeace

Wizard wrote: Ordered one and the kit has arrived.
Time to start assembling amplifiers.

On gumtree found a pair of AR18LS loudspeakers for only 600 ront, so decided these would be matched with the to-be-built amplifier.

DAMMIT!!! >☹

You must have stolen those from under my nose.. Was in heavy correspondence with the seller. Good buy! ?

Ah the gainclones. Yeah I've seen these kits; look mighty cool! Actually considered getting a set before I decided to get a bit more hectic. Busy building 2 AB 80W mono's designed by a Serb.

On that note, and don't mean to hijack - but this could be useful for you too - anyone know where to get heatsinks for min bucks in SA? Like maybe extruded aluminium directly from the factory?

Wizard

makepeace wrote: DAMMIT!!! >☹
You must have stolen those from under my nose.. Was in heavy correspondence with the seller. Good buy! ?

You were my competition? ?
After first telling me they were mine, he then told me someone else had shown heavy interest and was shifting to a first-come-first-serve basis.
Dashed out there last night.
Quite far from Claremont to GlenCairn!

Busy building 2 AB 80W mono's designed by a Serb.

Whoa. Respect.

On that note, and don't mean to hijack - but this could be useful for you too - anyone know where to get heatsinks for min bucks in SA? Like maybe extruded aluminium directly from the factory?

I'd like to know the answer too.
Although am favouring using a solid copper block between the two amplifiers as a heat sink.
My little amp is only 25w or so, so heat dissipation requirement is not the same as yours

Wizard

Alan Ratcliffe wrote: Hmm... I wonder... Could you stack six channels of these for 5.1?

A bit of googling ... and these have been used to make 5.1 amplifiers

Wizard

Here are the (few) components:

And the (hefty) torroidal transformer:

Psean

Seeing as we're bringing amp threads back from the dead today...
Any updates here Wizard?

Wizard

Matt Allison agreed to "assemble" this for me.
"assemble" in quotes - Matt says it took him 12 hours to do.
Not just a quick plug and play.

I am blown away.
Never thought I would own an amplifier that sounded like this.

It's now replaced my very old NAD 3225 PE hifi amplifier.

CD player --> Gainclone amplifier.

Volume control only.
No preamp.
No tonestack.
No balance controls.

Matt - you're a hero!

Wizard

Spot the hefty transformer. ?