Hello,
I'm looking to do the passive mods on my Lite dac-ah by removing the op-amps from the circuit.
Does anyone have the details for these mods? I've read that 2 resistors and 2 caps are needed, but did not find the step by step instructions.
Thanks in advance
I'm looking to do the passive mods on my Lite dac-ah by removing the op-amps from the circuit.
Does anyone have the details for these mods? I've read that 2 resistors and 2 caps are needed, but did not find the step by step instructions.
Thanks in advance
According to this schematic I found in a search :
the I/V resistors are R35 and R36 and you just need to move the +ve terminals of the output caps (C35,C36) from pin6 of the opamp to pin3 to bypass those AD847s (or as shown here, NE5534s).
the I/V resistors are R35 and R36 and you just need to move the +ve terminals of the output caps (C35,C36) from pin6 of the opamp to pin3 to bypass those AD847s (or as shown here, NE5534s).
Thanks for the replies.
Should there be any caps and/or resistors in between pin 3 and the RCAs after bypassing the op-amps?
Some use a 2.2 uf and I've also read 100 uf + 22K resistors mentioned below
https://www.highfidelityreview.com/lite-dac-ah-revisited.html
Should there be any caps and/or resistors in between pin 3 and the RCAs after bypassing the op-amps?
Some use a 2.2 uf and I've also read 100 uf + 22K resistors mentioned below
https://www.highfidelityreview.com/lite-dac-ah-revisited.html
Attachments
Ho Flo. I did this mod back in 2006! There is a lot of information on Head Fi and I have in fact found a lot of printed pages I made from the Head Fi site back then.
Below is a link to the main mod pages from 2006 but it does not seem to have many of the pictures that were posted at that time. From memory I did not use any resistors when installing the NOS mod caps but it was a long time ago.
When I removed the opamps I installed 8 pin dil sockets so that I could reverse the mod easily if I wanted to. In fact I was not that impressed with the NOS mod and re-installed some opamps.
The biggest gain IMO was to correct an error in the circuit caused by what was found to be an error in the values of resistors R35 and R36. These were found to be 270 ohms and could cause the TDA 1543s to exceed their maximum voltage swing. The ideal values should have been around 160 ohms. Soldering a 470 ohm resistor across R35 and R36 corrects the error.
https://www.head-fi.org/threads/help-me-get-to-know-my-dac-ah-280kb-pics.164399/page-10
Regards
Rob.
EDIT. I have just re-read the post from Abraxalito and it seems that you do not need to remove the opamps.
Below is a link to the main mod pages from 2006 but it does not seem to have many of the pictures that were posted at that time. From memory I did not use any resistors when installing the NOS mod caps but it was a long time ago.
When I removed the opamps I installed 8 pin dil sockets so that I could reverse the mod easily if I wanted to. In fact I was not that impressed with the NOS mod and re-installed some opamps.
The biggest gain IMO was to correct an error in the circuit caused by what was found to be an error in the values of resistors R35 and R36. These were found to be 270 ohms and could cause the TDA 1543s to exceed their maximum voltage swing. The ideal values should have been around 160 ohms. Soldering a 470 ohm resistor across R35 and R36 corrects the error.
https://www.head-fi.org/threads/help-me-get-to-know-my-dac-ah-280kb-pics.164399/page-10
Regards
Rob.
EDIT. I have just re-read the post from Abraxalito and it seems that you do not need to remove the opamps.
Today I made an interesting discovery at this DAC that I also have.
Some very thin wires are placed from the sound board to the RCA outputs through which the sound circulates. I replaced them with speaker cables that have many thin wires. The sound has improved.
I can't believe that they ruined the sound of this DAC even before it was released on RCA with those wire jokes.
In the following picture: the white wire is the original one, the other is the usual speaker cable.
https://ibb.co/BcFNsxy
Some very thin wires are placed from the sound board to the RCA outputs through which the sound circulates. I replaced them with speaker cables that have many thin wires. The sound has improved.
I can't believe that they ruined the sound of this DAC even before it was released on RCA with those wire jokes.
In the following picture: the white wire is the original one, the other is the usual speaker cable.
https://ibb.co/BcFNsxy