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Old 30th August 2013, 10:46 AM   #11
Vigo is offline Vigo  Sweden
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Thanks for you advice.

Do anyone know where i could buy a PCD for a Salas SSLV.

If i can't get hold of a on of those, i think i will buy a pcd from Sjöström Audio
and use instead.
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Old 30th August 2013, 01:40 PM   #12
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Quote:
Originally Posted by Avro Arrow View Post
Here is something I built. Works great!
You can eliminate the virtual ground and use output caps if you wish.

That's a very cool circuit. I'm not a fan of virtual grounds, but using the voltage regulators as CCS's is very clever. (I know it's nothing new.)

I've heard that you can use a voltage regulator as an audio amplifier. I never tried it, but I can see how it would work. I don't know if it would work very well or not.

This circuit could easily be built by a novice on a perfboard.

Last edited by Fast Eddie D; 30th August 2013 at 01:43 PM.
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Old 30th August 2013, 03:15 PM   #13
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I also designed one with a transistor CCS as well.
I have not built this one.

I matched my MOSFETs, and with the timmers,
you can adjust the output offset to almost zero.
After it warms up (a few minutes), offset drifts very little.
Mine was built on perfboard and an old AMD Athlon heat
sink. With an 18 volt supply, it only ran warm.
Offset was under 10mV at startup and settles to less
than 5mV when warmed up.
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Old 30th August 2013, 03:17 PM   #14
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Quote:
Originally Posted by Fast Eddie D View Post
I've heard that you can use a voltage regulator as an audio amplifier. I never tried it, but I can see how it would work. I don't know if it would work very well or not.
Like this?
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Old 30th August 2013, 03:27 PM   #15
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Quote:
Originally Posted by Avro Arrow View Post
Like this?

Yes, but the op amp buffer and CCS are icing on the cake. That is very nice.

The one I saw had no buffer or CCS. It was just a voltage regulator with a couple of resistors.
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Old 30th August 2013, 03:43 PM   #16
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Quote:
Originally Posted by Avro Arrow View Post
I also designed one with a transistor CCS as well.
I have not built this one.

I matched my MOSFETs, and with the timmers,
you can adjust the output offset to almost zero.
After it warms up (a few minutes), offset drifts very little.
Mine was built on perfboard and an old AMD Athlon heat
sink. With an 18 volt supply, it only ran warm.
Offset was under 10mV at startup and settles to less
than 5mV when warmed up.
That's a very nice, basic circuit. Is the transistor CCS better than the voltage regulator one, or not?

That MOSFET follower sure seems popular around here. It goes against my grain though; I am from the Walt Jung school of thought; I like to control everything precisely with feedback, caveats and all. In fact I have never employed discrete FETs of any kind in my circuits. When I went to school FETs were just being introduced into industry. I have used FET input op amps though; including the CA3140 which was about as good as it gets for audio filter circuits (tone controls) back in the day. This was way before the 5532/5534.

I know that zero feedback buffers have their merits, but on paper they look terrible. It's results that count though so don't label me a hater.
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Old 30th August 2013, 07:22 PM   #17
Zigis is offline Zigis  Latvia
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Quote:
Originally Posted by Fast Eddie D View Post

The one I saw had no buffer or CCS. It was just a voltage regulator with a couple of resistors.
I built output stage only from J.Broskie 24V Aikido schematic:

24V Aikido Line Stage and Headphone Amplifier

Just 2 x LM317 and 2 resistors, sounded really good.
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Old 1st September 2013, 01:14 AM   #18
JimT is online now JimT  Canada
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The Salas SSLV is available in the Group Buy section

Jim
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Old 1st September 2013, 06:30 AM   #19
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Quote:
Originally Posted by Zigis View Post
I built output stage only from J.Broskie 24V Aikido schematic:

24V Aikido Line Stage and Headphone Amplifier

Just 2 x LM317 and 2 resistors, sounded really good.
Thanks for this. That is ridiculously simple and versatile too. I have seen a few circuits like this and kind of scoffed at them. I should give it a try. I already have evil plans.

I'm glad you mentioned the switching power supplies. I have a stack of servers that I got out of an electronic recycling drop off (along with a Marantz receiver that only cost $1.00 to fix and a Sony CD player that only needed cleaning and lube of the moving parts ) and have a whole bunch of parts for high power switching supplies. In fact, I was thinking about using some of them for a power amp supply. I think you could filter the noise out.

You could build some really small (physically) amplifiers with some of this stuff is what I'm thinking. I also have a bunch of fans of various sizes from my plunders. I realize that the switching supplies do get pretty hot.

Last edited by Fast Eddie D; 1st September 2013 at 06:32 AM.
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Old 20th September 2013, 08:03 AM   #20
Vigo is offline Vigo  Sweden
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New idea, i was planing thinking about building something like this. This a concept i have seen used a lot, but not as a head amp.

I plan do use a bias of about 1amp so that i will run mostly in class A, if my understanding of how it works is correct. Could be wrong as i am not good with electronics.
I am also nut sure what values to use for the resistors R3 and R4, any suggestions how calculate that?

Will this work?

Click the image to open in full size.
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