You wont get any sound if the input (center post of RCA) is grounded. For future tests, just make up some RCA plugs, grounding center to ground lug. To temporarily short inputs, like when setting bias on some amps, or as here grounding input to see if amp is causing hum....with inputs grounded if it does not hum, problem is generally upstream, if hums with inputs shorted its in amp generally. then you can remove shorting plugs and proceed.
It will not play music with center post grounded...only the ground tab should be going to ground, input should go in amp....it is in "mute" status.
Russellc
Last edited:
sry Russelc, I dont know where my mind was at the moment i wrote the response (probarly i a bottle of mr. heineken 😀) but the grnd wasnt shorted when i wrote my response.
i will do some troubleshooting later tonight.
Q1A & Q1B tied face to face?
I've seen a number of photos that show Q1A & Q1B tied face to face with a tie wrap. Is this a common practice? What is the benefit? Should I do the same?
TIA,
John
I've seen a number of photos that show Q1A & Q1B tied face to face with a tie wrap. Is this a common practice? What is the benefit? Should I do the same?
TIA,
John
Tie wrap or shrink sleeve?
I tried the tie wrap. The smallest size that I have is too bulky. Might heat shrink offer the same result?
I tried the tie wrap. The smallest size that I have is too bulky. Might heat shrink offer the same result?
Hello BobEllis. How can I match Q5/Q6 and Q7/Q8? I know how to match Q1A with Q1B, is the same method used?
TIA
matching
Jpaul,
Here are a couple of articles that describe Vgs matching:
http://www.firstwatt.com/pdf/art_matching.pdf
http://www.firstwatt.com/pdf/art_mos_test.pdf
Cheers,
Dennis
Jpaul,
Here are a couple of articles that describe Vgs matching:
http://www.firstwatt.com/pdf/art_matching.pdf
http://www.firstwatt.com/pdf/art_mos_test.pdf
Cheers,
Dennis
About that: As I saw the Jfet tied on the build guide, I decided to do the same on my Aleph J. On the first board, I tried to tied them after soldering, so the Jfet are in contact only at their top end (on the second board, learning from my mistake, I tied them before soldering).
Will it cause any problem?
tiny pins don't like any sort of pressure or pull
re-flow solder joints , that will loosen them (pins)
re-flow solder joints , that will loosen them (pins)
Thanks. I'll fix this.
Concerning the small hum I talked about page 147, I discovered this morning that, with no sources connected, it disappears completly. The amp is dead silent on both channel.That's reassuring.
Stupid me!!!! This morning, I cleaned the mess left during the building of the amp and I found a forgotten capacitor.😱 It's the 0.0033µF cap which should be paralleled with the primaries of the transformer.
What's the purpose of this cap? My PSU seems to work well without it? Cancelling some noise when swicthing amp on or off?
Anymay, I'll put it in place this afternoon.
You can throw tomatoes, if you want.😀
What's the purpose of this cap? My PSU seems to work well without it? Cancelling some noise when swicthing amp on or off?
Anymay, I'll put it in place this afternoon.
You can throw tomatoes, if you want.😀
cleaning garbage from mains and suppressing rectifying noises
leave it out or put in , your choice
for proper dimensioning of that part - there is a thread about gadget strictly made for that purpose - but I forgot it's name
hopefully someone will chime in , to refresh my ( faint ) memory
edit- not enough coffeine in blood - now I re-read your post ......
cap on primary side = cleaning garbage form mains ; spark decreasing caps - across (each) section of mains switch
cap on secondary side - what I wrote above
leave it out or put in , your choice
for proper dimensioning of that part - there is a thread about gadget strictly made for that purpose - but I forgot it's name
hopefully someone will chime in , to refresh my ( faint ) memory
edit- not enough coffeine in blood - now I re-read your post ......
cap on primary side = cleaning garbage form mains ; spark decreasing caps - across (each) section of mains switch
cap on secondary side - what I wrote above
Last edited:
My right channel has become much weaker thank the left over time. I have tried different sources, and swapped speaker cables. The 2 channels were equal at the start.
Other than going over the bias and offset settings again, any suggestions as to what might have gone bad?
Other than going over the bias and offset settings again, any suggestions as to what might have gone bad?