Hi Mister Mile,
I'm thinking about creating a PCB for this amplifier.
Do the MJE350 (in series with BC557) and the MJE340 (in series with BC547) need a heatsink?
Thank you.
Hi, nice build. is this your own layout of AA9 or the one posted by me? what is the bias level and how does it sound?
Did you have to make any modifications or the original scheme values?
reg
Prasi
Thank you Mister Mile.
Other question: the 2SK2145 JFET's are available only in a very tiny SMD package. Could I replace these by two PN4392 ?
Thank you
Prasi it is your layout ,I was changing r12 to 3k9 and trimer to 10k. The bias is now 1300 mA. and it sound very good ,strong bass and nice mids and highs.
Roly the schematic is in post# 9551, the transistors are 2N5551 and 2N5401 SMD.
Layout in pdf in attached .
Roly the schematic is in post# 9551, the transistors are 2N5551 and 2N5401 SMD.
Layout in pdf in attached .
You can glue a small dedicated heatsink for the ICs that is available from most electronic parts sellers.
First draft AX22 PCB
I finished a first draft of the PCB for the AX22. The PCB is about 132 x 58 mm and is double sided (partially due to the SMD component). The idea is to mount the PCB to the heatsink. I wanted to keep the PCB size as small as possible so that the height of the heatsink is not to high (should I ever build it in an enclosure).
I did make a few modifications:
* I did not layout the PRO parts because I don't use that.
* I replaced the 2.2uF caps on the rails by 470uF caps.
* I used an input cap of 1uF (replaced the 1M resistor by 33k) to remove any DC component from the input signal.
* replaced the 47p cap on the input by a 470p cap (smaller bandwidth).
The 2SK2145 part is really very very tiny... I wonder if I will be able to solder that. Does anyone have some experience with hand soldering tiny SMD's?
I finished a first draft of the PCB for the AX22. The PCB is about 132 x 58 mm and is double sided (partially due to the SMD component). The idea is to mount the PCB to the heatsink. I wanted to keep the PCB size as small as possible so that the height of the heatsink is not to high (should I ever build it in an enclosure).
I did make a few modifications:
* I did not layout the PRO parts because I don't use that.
* I replaced the 2.2uF caps on the rails by 470uF caps.
* I used an input cap of 1uF (replaced the 1M resistor by 33k) to remove any DC component from the input signal.
* replaced the 47p cap on the input by a 470p cap (smaller bandwidth).
The 2SK2145 part is really very very tiny... I wonder if I will be able to solder that. Does anyone have some experience with hand soldering tiny SMD's?
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Wauw Thimios, that a nice job. What tools did you use (special soldering tip, flux, etc)?
Ha ha,special soldering tip, flux......nothing my friend!
Just an 25W soldering iron(ERSA) and 0.5mm solder wire.
MULTITIP 910BD: ERSA precision soldering iron Multitip C15, 15 W, 230 V at reichelt elektronik
Attachments
A2
I have built the preamp Apex A2 with NE5532. Sounds great, is easy to build and cheap. Super as a pre-amplifier for meters, small amps, test purposes ...
It may be that someone finds it useful.
Unfortunately, there are many different potentometers footprints and so I for myself had not the right one on the shelf. So be careful 😉
regards Olaf
I have built the preamp Apex A2 with NE5532. Sounds great, is easy to build and cheap. Super as a pre-amplifier for meters, small amps, test purposes ...
It may be that someone finds it useful.
Unfortunately, there are many different potentometers footprints and so I for myself had not the right one on the shelf. So be careful 😉
regards Olaf
