Nono, the Ussa 5 (on the 11th you said this: "I don't have test A/B yet between Ussa 5 and AN39 i hope soon....").
Καλησπέρα Αndy
As you can see, since I haven't finished the amplifier in the second channel, the power supply is missing.........when I finish it, I will do the test. However, what I received from one channel is very very promising. No noise at all .No grounds connections from all ...haha ....😉😉😉😆😆😆
Greetings,
A quick question before I begin setting up to test. I would like to confirm that if using a molex box for X143, the output would be from pins 1 and 2, and these would attach to the resistor load I will be using for testing. I have attached a schematic. Thanks for the help.
MM
A quick question before I begin setting up to test. I would like to confirm that if using a molex box for X143, the output would be from pins 1 and 2, and these would attach to the resistor load I will be using for testing. I have attached a schematic. Thanks for the help.
MM
I would agree with Nikos:
There's lots of current passing through the spkr terminals - I would suggest spades are a much better alternative for this purpose.
Nikos and Andy,
I had to change the Molex cables out in my SLB, so I know a bit about the perils. Since I have the molex box's cabled already, I will use them for the test part, and then decide on whether to remove both of the N and P molex boxes and the output molex box. Thanks for the advice.
MM
I had to change the Molex cables out in my SLB, so I know a bit about the perils. Since I have the molex box's cabled already, I will use them for the test part, and then decide on whether to remove both of the N and P molex boxes and the output molex box. Thanks for the advice.
MM
@Kokanee
Miles,
Because the schematic you have posted is also trying to establish a relationship between the pin tabs marked X144 and X145, it somewhat obscures the association of which Molex pins (in X143) are the “+” output and which are the “-“ output. As such, allow me to show you another schematic and picture:
Now you can see pins 1 or 3 (or both) are the true (+) signal outputs and pins 2 or 4 (or both) are the analog signal ground. So your resistor can connect across them.
With your DMM you can double check this. The junctions of R141, R142 and R143 are all on the same pad trace that connect to the pins 1 and 3 of X143. These are your “+” outputs. As such, the other two pins 2 and 4 should have continuity with the faston tab marked “0V” and are your analog output signal “-“ :
Also you’ll see a clean break in the trace within the Molex X143 silkscreen above. Of course your load resistor doesn’t care which side it is connected to just as long as it is from + signal output to analog signal ground (0V).
Best,
Anand.
Miles,
Because the schematic you have posted is also trying to establish a relationship between the pin tabs marked X144 and X145, it somewhat obscures the association of which Molex pins (in X143) are the “+” output and which are the “-“ output. As such, allow me to show you another schematic and picture:
Now you can see pins 1 or 3 (or both) are the true (+) signal outputs and pins 2 or 4 (or both) are the analog signal ground. So your resistor can connect across them.
With your DMM you can double check this. The junctions of R141, R142 and R143 are all on the same pad trace that connect to the pins 1 and 3 of X143. These are your “+” outputs. As such, the other two pins 2 and 4 should have continuity with the faston tab marked “0V” and are your analog output signal “-“ :
Also you’ll see a clean break in the trace within the Molex X143 silkscreen above. Of course your load resistor doesn’t care which side it is connected to just as long as it is from + signal output to analog signal ground (0V).
Best,
Anand.
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Thanks Anand,
I never did build the AN39 and so I'm not the guy to advice Myles!
I have just ordered (and paid!) the first A40 from VeraFi and hope to have it in Oz within the next month.
I really need to find out more about this amp. At the time it was a doodle on a Cafe napkin and I really need to listen to the commercial version, thanks to XRK, Mark, Anthony, Jan and JPS.
HD
I never did build the AN39 and so I'm not the guy to advice Myles!
I have just ordered (and paid!) the first A40 from VeraFi and hope to have it in Oz within the next month.
I really need to find out more about this amp. At the time it was a doodle on a Cafe napkin and I really need to listen to the commercial version, thanks to XRK, Mark, Anthony, Jan and JPS.
HD
Thank you Anand,
The schematic you posted is less busy. I am in the process of changing my Moles cables out to soldered leads and spades. Thank you for the clarification as I was on the way to installing the spades in a horizontal position (pin1-pin2) rather than vertical (pin1-pin3). I will check everything more than once before powering up.
Hugh, I hope you enjoy the A40, it looks great. I will look forward to your review.
MM
The schematic you posted is less busy. I am in the process of changing my Moles cables out to soldered leads and spades. Thank you for the clarification as I was on the way to installing the spades in a horizontal position (pin1-pin2) rather than vertical (pin1-pin3). I will check everything more than once before powering up.
Hugh, I hope you enjoy the A40, it looks great. I will look forward to your review.
MM
With .au specification power toroids? Or will you be using a step down transformer?
(And did postage cost more than the RRP?!)
I've said it before and I'll say it again: it's how it clips that matters.
That is: the perfect amp is superlinear (and inherently so) below a few watts, then starts producing H2 as we head towards clipping, which happens without fuss (that is, softly & sans ringing) and recovers instantly. All regardless of load.
This is the opposite of the typical high-gain, AB amplifier architecture. Which measures really, really well for the first few watts. And almost until cliping, as long as you ignore the IMD from capacitor recharge. And when it does clip, not only does it clip very harshly & all the way through the amp but all the "fixed" bias points and current sources are all knocked off kilter, which can take a long (RC) time to recover. Meanwhile, the amplifiers loop gain and stability are anybody's guess.
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There are some component value differences between the AN8R circuit and the AN4R circuit - in addition to the +/- DC rail values.
It was previously reported that someone who built the AN8R version (with +/-27v or 28v DC rails) found that it didn't like his 4ohm spkrs; OTOH I built the AN4R version (with +/-21v DC rails) and it drives my 4ohm spkrs excellently.
Then it would seem ... you're on your own, rdb!
No one has built a 4R version with 28v rails.
You may have to pay Hugh for some work with LTspice?
I guess the question is ... why do you want 28v rails for the 4R version? Presumably, for greater power than 21v rails deliver?
I'm getting 45w into 4 ohms from my 21v rails - with quite a lot of heat output. 28v rails would produce a lot more heat - I think you'd need fans for this. (Which produce noise.
)