Aleph J illustrated build guide

[beedlo]

I definitely have some cable tidying to do🤣.

I’ll be busy for a while with the list of things you’ve given me to try. Thanks!

 

[neric34]

Thx.
With RCA center +IN / outer GND / jumper -IN GND, there is a buzz.
With RCA center +IN / outer -IN, no buzz. Is it possible to keep this solution ? ...Is it dangerous ?

 

[sov]

The tweak with jumper in place:
10ohm and a cut trace

 

[neric34]

Thx.
With RCA center +IN / outer GND / jumper -IN GND, there is a buzz.
With RCA center +IN / outer -IN, no buzz. Is it possible to keep this solution ? ...Is it dangerous ?

"The tweak with jumper in place:
10ohm and a cut trace" ?? Should the circuit be cut ?

 

[sov]

See here

Yes, it is a common tweak for Aleph J. On backside of PCB you can see where I cut the copper a replaced the gap with a resistor.

 

[neric34]

With RCA center +IN / outer -IN, no buzz. Is it possible to keep this solution ? ...Is it dangerous ?

 

[sov]

Dangerous, no but you got an amplifier without gain and not so good sound it can produce. Se charts
I like amps with low gain myself. Playing with gain of 4dB right now.

 

[neric34]

If I connect like that I don't have any gain?

 

[sov]

Use XLR instead if you have that option.
Otherwise I will not recommend or approve that connection. Connect RCA as shown earlier. It’s just a jumper away.

 

[beedlo]

I found a (perhaps the) mistake I made... I had mixed the transformer primary wires. I was wiring it like this:

After swapping 1 and 3, the buzz coming from the transformer is significantly reduced. The buzz coming out from the speaker also greatly reduced...

I happened upon freejazz00's posts while I was looking for ideas to try. I wonder if he had the same issue. The thermistors would definitely get hot.

My wiring definitely still needs to be redone and will try the hum breaker as well. I also have rectifier snubber boards from ThatcherDIYAudio I can try.

Internal wiring inspired by works of Sergio Lione?

"There is no buzz if no amp boards are attached. It buzzes with one amp board is powered. It buzzes more when both channels are powered. So it seems to increase by load to the power supply. This is with no speakers attached! " ... so it ain't DC-on-mains issue

Can't see which wire goes where... you need to segregate wiring... low signal, DC, speakers, mains...

Drop bias to 400mV... that should help.

It seems that you have possible oscillations that might be causing excessive power drain from the toroids... measure the voltage drops across the PS PCB CRC... across Rs, and see what you have there. Then compare to see if the voltage drop across those resistors is the sum of the quiescent current from both AMP PCBs. Or, put an oscilloscope on V + and V - OUT, and check...

The best place for the snubber is as close as possible to the secondary wiring.... hence, you could install the snubbers on the bridge rectifiers... just use dual lugs and re-crimp... or use something like this:

View attachment 1230794

The fact that your speakers are buzzing as well tells me that you need an AMP PCB ground lift mod. Do you really need to keep RCA INs?

 

[Ben Mah]

Not sure how you have now connected your transformer so here is the PS schematic:

 

[Extreme_Boky]

 

[sov]

If I connect like that I don't have any gain?

No gain, keep it like that, just add a jumper between GND and -IN and you will be rewarded. If buzz with jumper do the trace cut and add a resistor.

 

[neric34]

...with XLR sockets, is there less risk of buzz? It seems to me that those who have them do not encounter this problem.
What do you think ? ...if this can avoid desoldering the transistors and cutting the printed circuit...?

 

[sov]

Balanced signal IN 👍

 

[neric34]

Sorry I'm a noob I didn't understand....that means yes for the xlr ? no buzz with xlr ?

 

[Dennis Hui]

Do you have a preamp with balanced out?

 

[neric34]

I have a nuprime dac-9 with xlr and rca.

 

[neric34]

...RCA connections are better for home use, right?

 

[rhthatcher]

Have you done the "rotate the donut" test? Input shorted to ground. Loosen up donut bolt a little. Put your ear up next to crappy test speaker. Or use a headphone tester as shown in this article: https://hifisonix.com/wp-content/uploads/2019/02/Ground-Loops.pdf

Turn the donut until hum minimizes. There's a null point. Check the other channel.

Once that's optimized, tighten the bolt. Now start moving wires around in the amp with your ear up to the crappy test speaker or headphones. Does a certain position of input wire, speaker wires, PSU wires drop the noise floor?