Mark, 6L6, Mooley et al
In my quest for lower gain I've gone against the given advice.
I started by reducing R13 "the method-that-shall-not-be-mentioned" to 5K1.
Amp still sounded good.
So I then reduced R20 a little--to 18K.
Still sounds great.
I haven't measured anything other than with my ears--I trust my ears but I don't trust my lying brain.
However I'm happy......H.A.P.P.Y
t
In my quest for lower gain I've gone against the given advice.
I started by reducing R13 "the method-that-shall-not-be-mentioned" to 5K1.
Amp still sounded good.
So I then reduced R20 a little--to 18K.
Still sounds great.
I haven't measured anything other than with my ears--I trust my ears but I don't trust my lying brain.
However I'm happy......H.A.P.P.Y
t
R13 should be OK to lower, in fact you can go all the way to zero ohms with that one as it is really little more than an active type volume control e.g. a Baxandall type.
This is the upmarket version:
https://www.ti.com/lit/ug/tidu034/tidu034.pdf
One point to note although it shouldn't be an issue in practice is that lowering the resistor increases the correction voltage needed from the servo. In other words if the servo opamp output was (say) +1.5v before then it would be nearer +3v now. Absolutely no problem as long as the voltage is not to close to either rail meaning the opamp has run out of range for applying correction. You could lower the 1meg to compensate if that happened.
R20 to 18k
You mean R18 was 20k and is now 18k. That's fine too.
This is the upmarket version:
https://www.ti.com/lit/ug/tidu034/tidu034.pdf
One point to note although it shouldn't be an issue in practice is that lowering the resistor increases the correction voltage needed from the servo. In other words if the servo opamp output was (say) +1.5v before then it would be nearer +3v now. Absolutely no problem as long as the voltage is not to close to either rail meaning the opamp has run out of range for applying correction. You could lower the 1meg to compensate if that happened.
R20 to 18k
You mean R18 was 20k and is now 18k. That's fine too.
SGC whoops!
Mark or anyone who knows...
Recently I managed to lift the pad on the component side of the board on the Vee end of R17. Theres a thin trace leading towards the LM3886 but it sort of disappears under the white silkscreen along the board edge. I know this trace connects to the -V supply but I can't tell if there are any other stops along the way. I'm going to have to repair this with a short length of 24 ga solid wire. I need to know if pin 4 of the amp chip is a good tie point or if I have to run it to another component or all the way to the Vee input of the board? The junction of C12 to Vee looks promising but the 3886 pin 4 is the closest.
Thanks in advance!
Mark or anyone who knows...
Recently I managed to lift the pad on the component side of the board on the Vee end of R17. Theres a thin trace leading towards the LM3886 but it sort of disappears under the white silkscreen along the board edge. I know this trace connects to the -V supply but I can't tell if there are any other stops along the way. I'm going to have to repair this with a short length of 24 ga solid wire. I need to know if pin 4 of the amp chip is a good tie point or if I have to run it to another component or all the way to the Vee input of the board? The junction of C12 to Vee looks promising but the 3886 pin 4 is the closest.
Thanks in advance!
The VEE end of resistor R17 is routed to pin 4 of the LM3886 ("VEE") and nowhere else. It's a point-to-point connection with no branches, stubs, intersections, or subdivisions.
I'd use insulated wire, probably AWG-30 "wire wrap" wire, to replace the missing trace. There are plenty of high voltage, high current nodes in that region and an accidental short to one of them would be disastrous.
I'd use insulated wire, probably AWG-30 "wire wrap" wire, to replace the missing trace. There are plenty of high voltage, high current nodes in that region and an accidental short to one of them would be disastrous.
I also have a switch on and off thump also .
My input voltage is + and - 27 v smps meanwell power supply.
can l use the same value of 22k resistor in series with 22 v or 24 v zener in place of the 33k mute resistor at R17?
there is a little bit of buzz with ears right close to the markaudio 12 p speakers with the input shorted.
Otherwise, it sound very natural across the entire frequency range . BIG soundstage wll beyond the speakers and music surrounds you .
The amp and power supply generate almost no perceptible increase in temperature after many hrs of use.
I use AB epoxy resin glue to keep the inductor in place.
Otherwise, it sound very natural across the entire frequency range . BIG soundstage wll beyond the speakers and music surrounds you .
The amp and power supply generate almost no perceptible increase in temperature after many hrs of use.
I use AB epoxy resin glue to keep the inductor in place.
First attempt at this
Hello all!
I just received my parts for the Super Gain Clone and PS, well except for the chassis and some out of stock caps on the way from digikey. If I may ask a very basic question, what is the difference between this and the Amp Camp amplifier. Other than the internal PS, 40 watts vs 8 watts, and number of parts involved? The price seems to be about the same, well at least the same order of magnitude anyway.
Hello all!
I just received my parts for the Super Gain Clone and PS, well except for the chassis and some out of stock caps on the way from digikey. If I may ask a very basic question, what is the difference between this and the Amp Camp amplifier. Other than the internal PS, 40 watts vs 8 watts, and number of parts involved? The price seems to be about the same, well at least the same order of magnitude anyway.
Where to even start...
The ACA is a niche product that caters for those who want to go down the low power Class A single ended route. By that very definition the ACA runs hot, it has a low power output that is greatly affected by whatever you hang on the end of it but when all that is said and done it can sound truly wonderful and really engaging.
The LM3886 based design is, whichever way you flip it, a chip amp. That means cool running and efficient (compared to the Class A) and this one has an output that is not affected by what you dangle on the end of it. It has lower distortion, much better drive ability... but does it sound as good?
They will certainly sound very different one vs the other. Only you can decide which you prefer
The ACA is a niche product that caters for those who want to go down the low power Class A single ended route. By that very definition the ACA runs hot, it has a low power output that is greatly affected by whatever you hang on the end of it but when all that is said and done it can sound truly wonderful and really engaging.
The LM3886 based design is, whichever way you flip it, a chip amp. That means cool running and efficient (compared to the Class A) and this one has an output that is not affected by what you dangle on the end of it. It has lower distortion, much better drive ability... but does it sound as good?
They will certainly sound very different one vs the other. Only you can decide which you prefer
This is like asking what is the difference between a Dodge Hellcat and Ford F-250. Both have four wheels and engines and lots of parts. Completely different types of vehicles, though.
The Amp Camp amp and and a good LM3886 amp are completely different types of amplifiers with different performance goals and implementations. They are as similar as apples and oranges, even though they are still both "amplifiers".