VDO - the AJ is only DC coupled if you jumper C1. Use a speaker protection relay if you wish. Some have, but I haven't blown up an amp connected to a speaker yet...
dodog - As ZM said, the net value of the resistors in parallel is high, even at 240V it limits peak current to 5.3A. Something that limits the inrush to 10A or so is more appropriate using a closely rated slow blow fuse. Just use the thermistor that Papa suggests, or two in series if you are in a 240V area. CL-60 or CL-70 for a normal AJ build http://www.mouser.com/ds/2/168/920-325D-LR-245176.pdf
dodog - As ZM said, the net value of the resistors in parallel is high, even at 240V it limits peak current to 5.3A. Something that limits the inrush to 10A or so is more appropriate using a closely rated slow blow fuse. Just use the thermistor that Papa suggests, or two in series if you are in a 240V area. CL-60 or CL-70 for a normal AJ build http://www.mouser.com/ds/2/168/920-325D-LR-245176.pdf
Last edited:
Hi Folks
First at al, Thanks for this great Amp , i ve just finish it 2 Weeks before and have listen a bit...
Ok after the Burnin i get some Matched IRFP240 for some Reason i was thinking i get it a Chance
and try to Chance them , after it was done i make a Test but for some reason that has not works so
well after trying to get the Bias right i give up
between
R16 350mV
R17 250mV
R18 350mV
R19 250mV
Before
R16 432mV
R17 397mV
R18 415mV
R19 396mV
Ok the next step was to change it back to it old Glory get the new IRFP out and the Good Old back ..
After that everthing has change everything was different on
R16 350mV
R17 150mV
R18 345mV
R19 150mV
after that i take a brake ... the next Day i change the 100K to a nother and it wass looking better than
before but not back to his old glory ... there was a difference of 50mV between before it was 30mV ,
i was thinking give the new IRFP a second chance... get it back and there it was the Problem again
a difference betwenn 150mV that was to this point of the Day the next step will be change it back to
the old IRFP ... but i thing there is not the Problem there might be something happend and i cant
find the Problem at this point i be more than happy for any kind of help at this point ... Thanks
at all
Cheers MATE
First at al, Thanks for this great Amp , i ve just finish it 2 Weeks before and have listen a bit...
Ok after the Burnin i get some Matched IRFP240 for some Reason i was thinking i get it a Chance
and try to Chance them , after it was done i make a Test but for some reason that has not works so
well after trying to get the Bias right i give up
between
R16 350mV
R17 250mV
R18 350mV
R19 250mV
Before
R16 432mV
R17 397mV
R18 415mV
R19 396mV
Ok the next step was to change it back to it old Glory get the new IRFP out and the Good Old back ..
After that everthing has change everything was different on
R16 350mV
R17 150mV
R18 345mV
R19 150mV
after that i take a brake ... the next Day i change the 100K to a nother and it wass looking better than
before but not back to his old glory ... there was a difference of 50mV between before it was 30mV ,
i was thinking give the new IRFP a second chance... get it back and there it was the Problem again
a difference betwenn 150mV that was to this point of the Day the next step will be change it back to
the old IRFP ... but i thing there is not the Problem there might be something happend and i cant
find the Problem at this point i be more than happy for any kind of help at this point ... Thanks
at all
Cheers MATE
Last edited:
you really should try to get the same voltages in a pair irfp240.
For example Q7 and Q8 are a pair so readings for R18 and R19 should fit together.
in your case:
R16 350mV
R17 150mV
R18 345mV
R19 150mV
readings for R17 and R19 are similar but thats not a pair.
try to swap the fets
hopefully that is what you want to know, and you understand my broken english
For example Q7 and Q8 are a pair so readings for R18 and R19 should fit together.
in your case:
R16 350mV
R17 150mV
R18 345mV
R19 150mV
readings for R17 and R19 are similar but thats not a pair.
try to swap the fets
hopefully that is what you want to know, and you understand my broken english
Hello.
I am almost totaly New at building my own Things, but I think I can learn a lot. I have got the boards and are about to find a fitting transformer. AnTek 500VA, 18V is ok as I can understand. I see the question about secondary windings when I am looking for parts to the PSU. Can anyone explain that? How do I know that about the Antek? I can not see any information on the website.
Regards
I am almost totaly New at building my own Things, but I think I can learn a lot. I have got the boards and are about to find a fitting transformer. AnTek 500VA, 18V is ok as I can understand. I see the question about secondary windings when I am looking for parts to the PSU. Can anyone explain that? How do I know that about the Antek? I can not see any information on the website.
Regards
this one should be fine, if antek make good transformers (i have no experience with antek)
AN-5218 - 500VA 18V Transformer - AnTek Products Corp
Electrical Characteristics
Outputs 2x Power 500VA Output Voltage Current 18V 13.9A
Should be 500VA with 2x18V
AN-5218 - 500VA 18V Transformer - AnTek Products Corp
Electrical Characteristics
Outputs 2x Power 500VA Output Voltage Current 18V 13.9A
Should be 500VA with 2x18V
hello is some days that I mounted steadily the Aleph j in my system that is thus formed:
phono preamp pass labs xono clone
Pre line aleph p 1.7 clone
naim cd player CD5x
power cables naim nac a5
Ekta great speakers
I've never heard him play so my system after I installed aleph j
the average high and fantastic clean, warm and detailed, it's the sound I've been looking for.
only problem is the low bit shallow, which is why I would like you a few questions:
such as power cables used with aleph J?
in full swing and after about an hour of operation, the bias voltage is about 0.37 v
increasing the bias and take it for example to 0.45 v, can 'help drive the bass?
there is something else to do for this problem?
thanks for the answers
Max
phono preamp pass labs xono clone
Pre line aleph p 1.7 clone
naim cd player CD5x
power cables naim nac a5
Ekta great speakers
I've never heard him play so my system after I installed aleph j
the average high and fantastic clean, warm and detailed, it's the sound I've been looking for.
only problem is the low bit shallow, which is why I would like you a few questions:
such as power cables used with aleph J?
in full swing and after about an hour of operation, the bias voltage is about 0.37 v
increasing the bias and take it for example to 0.45 v, can 'help drive the bass?
there is something else to do for this problem?
thanks for the answers
Max
Bob-
Honestly, I'll stop pestering you soon.
From an earlier post, you wrote:
I checked the transformer I have this morning and it's a 2x20V, 400VA.
400/120 = 3.3333333
Would it be best to start with a 4A fuse and, if it blows, work up to a higher one or should I just start with a 5A and work higher if needed?
Hi
After one day more to get the J up to run in his old Condition i need a brake and
might be some Help to find out what is wrong ...
I have follow the clou from Danger mouse and have some Change of the IRFP,
what at first has bring not so mutch , after 20 time soldering the IRFP in and out
i try out some Wire with a Terminal mounted to the IRFP that has helps a lot and
the J was Up and Running , i have Match all IRFP together , after that i was confident
that all will works fine and i have solder the IRFP back in place on the PCB but after
that the same Problem still exist on the Left Chanel (right just fine)
Q5 380mV
Q6 200mV
Q7 378mV
Q8 198mV
on the Wire (clamp with a Terminal)
Q5 347mV
Q6 335mV
Q7 345mV
Q8 339mV
there must be something else wrong and i cant find out what it is , at some point i thing take it be side ...
but it was runnig 2 and a halt week befor just fine withe the same IRPF with a difference of 30mV and
i realy miss it to listen ...
At this point i will conected the IRFP back on the Wire with the Terminal and will see how it goes that
is my only solution at this point it is not what wanted but i ve it has to be ...
i hope here is might be someone how can help me to find the right direction ...
1000time Thanks
Cheers Manuel
After one day more to get the J up to run in his old Condition i need a brake and
might be some Help to find out what is wrong ...
I have follow the clou from Danger mouse and have some Change of the IRFP,
what at first has bring not so mutch , after 20 time soldering the IRFP in and out
i try out some Wire with a Terminal mounted to the IRFP that has helps a lot and
the J was Up and Running , i have Match all IRFP together , after that i was confident
that all will works fine and i have solder the IRFP back in place on the PCB but after
that the same Problem still exist on the Left Chanel (right just fine)
Q5 380mV
Q6 200mV
Q7 378mV
Q8 198mV
on the Wire (clamp with a Terminal)
Q5 347mV
Q6 335mV
Q7 345mV
Q8 339mV
there must be something else wrong and i cant find out what it is , at some point i thing take it be side ...
but it was runnig 2 and a halt week befor just fine withe the same IRPF with a difference of 30mV and
i realy miss it to listen ...
At this point i will conected the IRFP back on the Wire with the Terminal and will see how it goes that
is my only solution at this point it is not what wanted but i ve it has to be ...
i hope here is might be someone how can help me to find the right direction ...
1000time Thanks
Cheers Manuel
Last edited:
I'd exchange the FETs in Q6 and Q7, that gives you tighter matching between pairs that need to be matched. Q5 must match Q6 and Q7 must match Q8. Matching between those two pairs in not necessary.
Are you saying that with the FETs connected directly to the board they behave differently than when connected to the boards with short pieces of wire (also called flying leads)? If so, that is really odd.
Are you saying that with the FETs connected directly to the board they behave differently than when connected to the boards with short pieces of wire (also called flying leads)? If so, that is really odd.
Hi Bob
You get it with solder direct to the PCB comes the problem...
and i ve they are conected viva wire it works just fine...
the last what i did was solder the Irfp to the Wire and there was the
problem again ...
i thing that has nothing to do with the miss matched IRPF
Next step contacted back to the wire viva Terminal... and try
i ve it runs and i ve its run i let it run for this day...
Thanks a lot
Cheers Manuel
You get it with solder direct to the PCB comes the problem...
and i ve they are conected viva wire it works just fine...
the last what i did was solder the Irfp to the Wire and there was the
problem again ...
i thing that has nothing to do with the miss matched IRPF
Next step contacted back to the wire viva Terminal... and try
i ve it runs and i ve its run i let it run for this day...
Thanks a lot
Cheers Manuel
Got to start somewhere............
Greetings- I ordered my Aleph J boards a couple of days ago and now I need to order the parts to stuff it with. Question- The Aleph J BOM, I assume that this is a listing of parts to populate one circuit board, so I need to order enough parts to stuff TWO circuit boards, correct? Mouser seems to have more parts than Digikey, is there any reaon to order elsewhere? I just need a few pointers to get going, I'm fairly good at figuring things out once I'm rolling. I'm basically a tube amp guy, so this solid state build is very new to me. Thanks for your help. Paul
Greetings- I ordered my Aleph J boards a couple of days ago and now I need to order the parts to stuff it with. Question- The Aleph J BOM, I assume that this is a listing of parts to populate one circuit board, so I need to order enough parts to stuff TWO circuit boards, correct? Mouser seems to have more parts than Digikey, is there any reaon to order elsewhere? I just need a few pointers to get going, I'm fairly good at figuring things out once I'm rolling. I'm basically a tube amp guy, so this solid state build is very new to me. Thanks for your help. Paul