AKSA's Lender Preamp with 40Vpp Output - Page 101

Skylar88 · 16th January 2019, 11:13 AM

I think once the main board and DB's are tested and working fine, it may be an option to solder the DB's to the main board. I've never felt very happy with the wobbly DB's. The cheapy header connectors were not designed to hold a board very tight and rigid without any other support. I've also considered adding support to the top edges of the DB's.

maf_au · 16th January 2019, 11:46 AM

Quote:

Originally Posted by twocents

Maf_au – I agree with X – beautiful work!

I would also advise to use socket connectors on the motherboard for R121 (the pot) for easier connecting to your panel mounted DACT volume switch.

Thanks!

Is there a best socket and plug connector for that R121?

Skylar88 · 16th January 2019, 02:36 PM

Any single or double row 0.1" (2.5mm) pitch connector will work. I used two rows of round pin PCB header.

maf_au · 23rd January 2019, 10:37 PM

Added some heatsinks to the transistors.

Main board: R141 to 10k
THT: R10 33k, and R11 6k8.
Couldn't get the Vishay Metal film resistors, so found some other Metal film resistors, not as accurate as the Vishay's.

Still waiting for the DACT SMD attenuator.

The cable from the X121 to X111, how do I know what side is to be correct between them?

maf_au · 23rd January 2019, 10:44 PM

Temp today outside will be at 46C degrees!!!

Skylar88 · 24th January 2019, 06:25 AM

Quote:

Originally Posted by maf_au

The cable from the X121 to X111, how do I know what side is to be correct between them?

I checked on the circuit diagram when I built mine.

maf_au · 24th January 2019, 06:25 AM

Done a bit more today.

Attached the AKSA to a timber board, attached the power board, found a previous LED cable, just need to know what resistor is needed for it. Put some PCB headers for the DACT attenuator (it's not here yet)

Just need to sort the power cable to the HP laptop power system, attach some RCA sockets and attach the DACT when it arrives and will see if it works!

xrk971 · 25th January 2019, 12:23 AM

For LED, 15k works well. Basically 45v and 15k gives 3mA which is not too blinding bright. 20k could work if you like a little but dimmer intensity.

Skylar88 · 25th January 2019, 06:24 AM

Quote:

Originally Posted by xrk971

For LED, 15k works well. Basically 45v and 15k gives 3mA which is not too blinding bright. 20k could work if you like a little but dimmer intensity.

It depends on the wavelength or color of the LED.

I've used 15k on the board plus an extra 56k in series (on the LED lead) to get a blue LED dim enough for night-time use. PSU is set to 48V.

maf_au · 27th January 2019, 03:30 AM

Ok. have been waiting for the SMD DACT, and still hasn't arrived.

Have and set a Mouser potentiometer 10KOhms 688-RK09L12D0A1W, connected it today.

The pre-amp only works on the right side. Can feel the right side of the THT is warm on the heatsinks, and the the left side is cold.

How do I test where the left side is not connecting or some other mistake.

The sound on the right side sounds good, but if I turn the potentiometer up to the normal volume on my old Musical Fidelity Preamp 3A it crackles in the speaker.

25th January 2019, 12:23 AM	#1008
xrk971 Got Foam? diyAudio Member Join Date: Oct 2012 Location: Metro DC area	For LED, 15k works well. Basically 45v and 15k gives 3mA which is not too blinding bright. 20k could work if you like a little but dimmer intensity. __________________ XRKaudio https://www.etsy.com/shop/XRKAudio

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16th January 2019, 11:13 AM	#1001
Skylar88 diyAudio Member Join Date: Jun 2017 Location: Pretoria	I think once the main board and DB's are tested and working fine, it may be an option to solder the DB's to the main board. I've never felt very happy with the wobbly DB's. The cheapy header connectors were not designed to hold a board very tight and rigid without any other support. I've also considered adding support to the top edges of the DB's.

23rd January 2019, 10:44 PM	#1005
maf_au diyAudio Member Join Date: Jun 2005 Location: Adelaide	Temp today outside will be at 46C degrees!!!

27th January 2019, 03:30 AM	#1010
maf_au diyAudio Member Join Date: Jun 2005 Location: Adelaide	Ok. have been waiting for the SMD DACT, and still hasn't arrived. Have and set a Mouser potentiometer 10KOhms 688-RK09L12D0A1W, connected it today. The pre-amp only works on the right side. Can feel the right side of the THT is warm on the heatsinks, and the the left side is cold. How do I test where the left side is not connecting or some other mistake. The sound on the right side sounds good, but if I turn the potentiometer up to the normal volume on my old Musical Fidelity Preamp 3A it crackles in the speaker.