After reading through the first few pages of this thread that talks about bias, and going by Grey's schematic, is the following correct?
1) The source resistor is R18?
2) Bias current = (voltage across R18)/(Resistance of R18)?
Thanks.
1) The source resistor is R18?
2) Bias current = (voltage across R18)/(Resistance of R18)?
Thanks.
Yup that's right, and you can adjust bias by applying Ohm's Law since the voltage across source resistor remains constant.
To increase bias current, is it okay to reduce the value of R18 but kept the value of R19 unchanged?
Member
Joined 2002
Well, i got the itch a few day's ago and well i fired up one of my stereo aleph mini's the ( smd version ) and what was a i missing SO MUCH detail.
Running one stereo aleph at the moment while i fix the other so i can bi-amp again.
Running a opa627 with all black gate caps as my pre-amp.
Was having problems with a passive volume pot, when i got the to middle there was no difference between 10-2 but after about 3 more bass arrived so i removed it for now then went back to my opa627 pre-amp.
Have a few mods to do but soon.🙂
Running one stereo aleph at the moment while i fix the other so i can bi-amp again.
Running a opa627 with all black gate caps as my pre-amp.
Was having problems with a passive volume pot, when i got the to middle there was no difference between 10-2 but after about 3 more bass arrived so i removed it for now then went back to my opa627 pre-amp.
Have a few mods to do but soon.🙂
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Nice looking piece you got there! Few questions though. PSU appears to be the snubberised chipamp.com PSU. How hot do the diodes get? Mine (only 4, not 8) are pretty hot and I don't think I can run mine without heatsinks with a bias current of ~1.25Amps.
No CCRC PSU by the looks of it, don't you have hum issues? How much capacitance does it have?
No CCRC PSU by the looks of it, don't you have hum issues? How much capacitance does it have?
Member
Joined 2002
the diodes get warm 🙂 but nothing blown up yet, ill be changing them to their big brother one's when i can afford it soon, and order 2 stereo chassis.
Hum, no hum 🙂
Does anyone know if BRIANGT still sells Aleph boards. Going to chipamp.com I find some on his ordering page but I am wondering if the site is still live. I tried emailing him but have not gotten a reply after several days.
I have been running one of his chipamps for several years and now would like to try some of that class A single-ended goodness.
Any thoughts...
Thanks,
Paul
I have been running one of his chipamps for several years and now would like to try some of that class A single-ended goodness.
Any thoughts...
Thanks,
Paul
Member
Joined 2002
I'll email him i have a direct email and let you know, how many boards are you looking for ? psu and a stereo set or ?
Jase
The site appears to be still live. On occasion there's a special offer for a limited time. October 5th, 2009, 20% off all kits until end of the month. Note that the special offer isn't there anymore.
Thanks guys. I would be looking for a complete stereo set with PS. It looks like he is still set up but I did not want to order before I made some sort of contact.
I appreciate the help. Great group on this board...
Paul,
I still have some Aleph boards left, along with the larger power supply boards that I made.
The boards are currently black with white silk screen:
amp set: http://chipamp.com/diyaudio/miniA-amp.jpg
psu board: http://chipamp.com/diyaudio/miniA-ps.jpg
Let me know if you have any more questions,
--
Brian
The quality of BrianGT's PCB's is very high, you will not be disappointed. Oh and this is indeed a great board. A lot of knowledgeable and helpful people here. My mini Aleph sounds gorgeous, that probably wouldn't be the case if it weren't for the people on this board and the wealth of information that's to be found here already.
Now go forth and make yourself a (mini) Aleph! Good luck! 🙂
Brian, will you order new Aleph and PSU PCB's if your current stock runs out? I might be interested in buying some more... Should I hurry or shouldn't I worry?
Oh and Brian can you bring me some coffee and rub my feet 😀 , Sorry couldn't resist. I ran out and checked my inventory of power supply boards - they are a very versatile board. While checking I noticed I have 4 mini-A built up (threw hole) 2 are complete mounted on heat sinks 2 are boards complete but not mounted. If some wants them email me we can discuss price (what ever they cost me).
Bill
Bill
Member
Joined 2002
I still have a decent number of boards in stock, and will continue to order more if I run out.
You sound like my wife in the morning 😀
I put the Aleph PCB sets up on-sale at 25% off, making it $6.75 for the pcb set. The set includes 2 amplifier boards and 4 output boards. I run this until the end of the month.
Happy Thanksgiving to all!
--
Brian
Member
Joined 2002