Using GC with singple power supply

[TonyF]

The national notes for the 1875 show it in both balanced and single power supplies, but the component values differ. I would like to use it in the usual GC inverting format but single power supply ( I want a cap between chip and speaker - don't ask why ....) . What changes are needed in the circuit to accomplish this ?
Tks in advance.

 

[ir]

it's all lin the National datasheet uner single supply application isn't it???

i too was going to build a single supply amp, then decided it
s just simpler to go for dual supply

 

[peranders]

Use only single supply only if you can't get a dual one. It's not simplier or easier really with a single supply. The big drawback is a fat cap i series with speaker.

 

[TonyF]

Thanks ir and peranders. The National notes do not inform me as to why dual and single systems end up with different circuit values. I was curious as to how the GC inverted option values change with a single supply.
I blew a Lowther vc some years ago when one rail of a dual supply packed up - the offset voltage which resulted was fatal and I am cautious about having a repeat ! I have a dual GC running and was about to embark on a rebuild...
Cheers

 

[analog_sa]

TonyF

The compromises involved with a single supply are simply not worth it. As i am quite paranoid about DC (used to have Lowthers too) i've tested both the 1875 and 3875 with one rail missing. Yes, there is a substantial DC at output but once you load it the current protection kicks in and the output drops down to 0v. I haven't had a look on the scope, so don't really know how long it takes for the protection to work, but experimenting with a cheap car speaker did not result any injuries.

 

[Hybrid fourdoor]

Im not sure I understand what you guys are talking about, but my interpretation of the question is that he wants to make a stereo pair that only uses one transformer. Isn't this how almost all amplifiers made are? It also seems to make sense, I mean if one 24V 2A transformer cost $10 and a 24V 5A transformer costs $13, it seems to make sense that you could save yourself some dough by using one larger one.

Am I missing something here?

I must admit I don't know a whole lot about all this stuff.

 

[ErikdeBest]

single supply

Hallo

With single supply the author of this threat means a 0V (ground) and +V. Most gainclones are built with double supply, which means -xV, 0V (ground) and +xV. The difference? Well, for a double supply you need two secondaries on your trafo, or a centertapped one. Lot´s of trafo´s have only one secondarie, resulting in a single supply.

 

[TonyF]

i've tested both the 1875 and 3875 with one rail missing. Yes, there is a substantial DC at output but once you load it the current protection kicks in and the output drops down to 0v.

Thanks analogue_sa - exactly the right helpful bit of information.
Cheers T

 

[ir]

i've also done that. when i built my amp a couple of weeks ago i was using a non-centre tapped transformer (all i had) it worked fine BUT, after about a minute of operation the -VE rail drifted from -22V down towards zero. once it got to -10 the chips' undervoltage protection kicked in and simply turned the chip off. it's brilliant really - saves any damage. i did consider the single supply setup but couldn't much be bothereed with the extra parts.
problem was rectified by simply finding a centre-tapped transformer 🙂