Hi All,
Given my limited experience (& budget) I decided to have a go at a clone using what I had laying around & 2 sample 3886's.
So far I have one chanel built & working, loosely based on Thorstens Inverted Gainclone. Impressions on sound are useless at this point as I have only been testing on an old 4Ohm car speaker.
Cost so far has been a whopping £11.50 as all but the 1uF, 2,2uF & 1000uF caps are from the scrap bin. Including the transformer from a 600VA UPS that had gone south. A worthy sum for an amp if you ask my wife
.
My main problem is that the transformer only has 1 secondary. Currently I am using 1/2 of a bridge to get + & - at 28.5V (at no load), with the the other side of the secondary tied to ground. I am pretty sure it won't drop too much under a normal amplifier load given the size of the damn thing
Is there a better way to use this transformer i.e. with 2 half bridges & still create a ground? Is it even wired correctly as it is?
Thanks in advance
Paul
Given my limited experience (& budget) I decided to have a go at a clone using what I had laying around & 2 sample 3886's.
So far I have one chanel built & working, loosely based on Thorstens Inverted Gainclone. Impressions on sound are useless at this point as I have only been testing on an old 4Ohm car speaker.
Cost so far has been a whopping £11.50 as all but the 1uF, 2,2uF & 1000uF caps are from the scrap bin. Including the transformer from a 600VA UPS that had gone south. A worthy sum for an amp if you ask my wife
.My main problem is that the transformer only has 1 secondary. Currently I am using 1/2 of a bridge to get + & - at 28.5V (at no load), with the the other side of the secondary tied to ground. I am pretty sure it won't drop too much under a normal amplifier load given the size of the damn thing
Is there a better way to use this transformer i.e. with 2 half bridges & still create a ground? Is it even wired correctly as it is?
Thanks in advance
Paul
Hi Paul,
you mean the "one way symmetric" from the picture?
It´s not the usual way to get dual voltages and is not recommended if you still have to buy a transformer but as it was lying in your scrap bin I´d say use it.
The following filtering has to be quite on a large scale to get you almost the same smooth voltage as with dual secondaries but fortunately the LM3886 has got a good PSRR value so it won´t matter that much.
Mostly people go for rather small capacitors with their gainclones anyway.
If you got more caps in your scrap bin I´d put them in as well to compense your "one way rectifying".
Just listen to the amp when it´s done. You might be happy with it like it is.
Jens
you mean the "one way symmetric" from the picture?
It´s not the usual way to get dual voltages and is not recommended if you still have to buy a transformer but as it was lying in your scrap bin I´d say use it.
The following filtering has to be quite on a large scale to get you almost the same smooth voltage as with dual secondaries but fortunately the LM3886 has got a good PSRR value so it won´t matter that much.
Mostly people go for rather small capacitors with their gainclones anyway.
If you got more caps in your scrap bin I´d put them in as well to compense your "one way rectifying".
Just listen to the amp when it´s done. You might be happy with it like it is.
Jens
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