Who wants a power amp kit for free? **Out of LM3886 kits**

[DreamSeller]

Ive just looked at the chipamp website and the power supply has me confused.

Im not even going to attempt to build the power supply before I understand a few things, I figure this is the best place to ask them.

1. I need help on which transformer to use, Ive made stuff to plug into mains before but that was using an AC transformer which was storebought to power the circuit which was a 12v regulated power supply

2.Which fuses? Ceramic, M205, 3AG,

These are my main concerns at the moment that I would like to overcome before attempting the power supply.

*EDIT* OK after reading a bit more I think what I need is a transformer at least 160 VA with 2 secondary winding between 18 and 25 volts, The only thing close to that I can easily get a hold of is a toroid, Will this work? The one I am looking at is Jaycar Cat Number MT-2113 (18 Volts) or MT-2114 (25 Volts).

I think I understand a bit more now that I have read the LM3886 build guide and looked at pictures from chipamp, but I would still rather be sure.

-Dream

[joecool85]

It's always a good idea to do research BEFORE building a project like this, so good job on that.  As far as a transformer goes, I recommend one of these:

Avel 25+25 250va toroidal http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=122-625

For the fuse I just used a 1 1/4" glass tube fuse.  Not sure how many amps it was...I think 3 amp.

[DreamSeller]

Rather than shopping over the internet I would go Jaycar. They have 25V 160VA or 18V 300VA.

Would the 160VA work, I ask because its around $20 cheaper

-Dream

[joecool85]

For a single LM3886 a 160va should be fine.  I got the larger one so I could add another channel if I wanted to.

[DreamSeller]

Cool thanks, And sorry dude I has no idead what the useless and informative things were so I just randomly clicked, I think I clicked useless. My bad.

Which tonestack would be good in this?

-Dream

[joecool85]

No worries.

As far as tonestack goes, its up to you.  I'm using a marshal preamp box on mine.  RDV built one but I keep forgetting what it was lol.

[Fixr1984]

I stand corrected.
The LM3886 will run on that transformer.
The 18v min is a [v+] + [v-] value which could even be 18vct.

RDV

So if that transformer will work,
How many watts are we talking here? How many volts would be ideal? How many volts to get full potential out of the chip?

[RDV]

To get full power you'll need either 36 to 50vct or a 18 to 25v dual secondary transformer with a VA rating of around 160. I little less or a lot more VA won't hurt. Just remember that any poweramp is only as good as it's power supply.

RDV

[RDV]

And to all:

Be careful with mains voltage!!

[joecool85]

^^ I second that.

I do still have that transformer if anyone is interested.  But even though it would work ok for a LM3886 setup, it would be ideal for a LM1875.

[BrianGT]

I hope all of you enjoyed the free kits

I prefer the 2x25vac avel transformers, and use a 330va one for my stereo 3886 amp.

--
Brian

[joecool85]

Just so everyone knows, BrianGT is the Brian from chipamp.com and he is the one who has supplied me with the LM3886 kits and LM1875 kits. 

A big thanks from all of us at SSGuitar!  Thanks Brian!

[RDV]

Yes indeed thanks to Brian!

I listen to my chipamp.com stereo every day. Now if I could just get those darned speakers right!  :duh

RDV

[joecool85]

btw, do we have some people ready for some build reports?  Questions?  How are those LM3886 kits coming guys?

[DreamSeller]

Just got my kit, Thanks Joe and Thanks Brian.

Just wondering on these things

-Which do I build, Whats the difference between the standard confiuration and the feedback capacitor

-What rating and voltage should the on/off switch have and where does it goe i.e. before or after the transformer

-What kind of fuse, 2A 3AG or M205 or Ceramic Fuses.

Thanks

-Dream

One other thing, I want to use the flipster as the preamp and power it from a different transformer, What is the safest way to hook two transformers up to one ac power supply.

Also is this power supply regulated?