Regurgitator kit Build Thread

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tlhpsound
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Re: Regurgitator kit Build Thread

Postby tlhpsound » Sun Aug 26, 2018 2:48 pm

OK. Thanks. I ordered another kit to pair them as stereo. To connect two boards side by side, do I need to connect all pins 1 to 5 of J1 header on one board with the corresponding pins 5 to 1 on J2 on the second?

Can I use OP275? With OP275, what voltage is optimum?

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Re: Regurgitator kit Build Thread

Postby Joe Malone » Sun Aug 26, 2018 4:26 pm

tlhpsound wrote:OK. Thanks. I ordered another kit to pair them as stereo. To connect two boards side by side, do I need to connect all pins 1 to 5 of J1 header on one board with the corresponding pins 5 to 1 on J2 on the second?

Can I use OP275? With OP275, what voltage is optimum?


You only need J1 to J2 pins 1 to 3 or 3 to 5 but all 5 will work fine.

OP275 is work well up to +/-18vdc
Joe :-)
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tlhpsound
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Re: Regurgitator kit Build Thread

Postby tlhpsound » Sat Sep 08, 2018 4:03 pm

OK. Thanks. I have another question. I ordered these kits as a make up gain for a stereo volume pot which I want to place after the DAC module. The application is a DIY car stereo using a Linux chip-on-the-board PC. I do not know the output impedance of the DAC. What would be the optimal impedance of the pot? I am looking at a 50k pot. Would this kind of configuration work?

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Re: Regurgitator kit Build Thread

Postby Joe Malone » Mon Sep 10, 2018 12:25 pm

tlhpsound wrote:OK. Thanks. I have another question. I ordered these kits as a make up gain for a stereo volume pot which I want to place after the DAC module. The application is a DIY car stereo using a Linux chip-on-the-board PC. I do not know the output impedance of the DAC. What would be the optimal impedance of the pot? I am looking at a 50k pot. Would this kind of configuration work?


A DAC will usually run 2k loads so a 5k to 10k log volume pot between the dac output and regurg +in should work perfectly with the regurg giving you makeup gain and balanced output.
Joe :-)

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tlhpsound
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Re: Regurgitator kit Build Thread

Postby tlhpsound » Thu Sep 13, 2018 11:51 am

OK. Thank you. One more question, please. What level of max. attenuation do you recommend on the pot? 50 dB is good? The spec of the DAC I am going to use is in the link below.

https://dl.khadas.com/Hardware/ToneBoar ... _Specs.pdf

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Re: Regurgitator kit Build Thread

Postby Joe Malone » Thu Sep 13, 2018 1:28 pm

tlhpsound wrote:OK. Thank you. One more question, please. What level of max. attenuation do you recommend on the pot? 50 dB is good? The spec of the DAC I am going to use is in the link below.

https://dl.khadas.com/Hardware/ToneBoar ... _Specs.pdf


If you want the pot to work as volume then wire the bottom of the pot to 0v ground and it will work as a normal full off to full on volume which is usually roughty -90 to 0. If you want to limit the off range you will need a extra resistor under the pot to 0v to stop it going fully off.
Joe :-)

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Re: Regurgitator kit Build Thread

Postby tlhpsound » Sun Sep 16, 2018 2:32 pm

Hi. I received the second kit. I compared it with the first one and noticed a minor difference. The second one has no beige component parts on Z01 and Z02. The first one does have parts in place. Is it intentional? Or it's an error?

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Re: Regurgitator kit Build Thread

Postby Joe Malone » Sun Sep 16, 2018 3:36 pm

tlhpsound wrote:Hi. I received the second kit. I compared it with the first one and noticed a minor difference. The second one has no beige component parts on Z01 and Z02. The first one does have parts in place. Is it intentional? Or it's an error?


When the ZD1 & 2 are not fitted sometimes the guys here fit extra mono caps there but either way will work fine.
Joe :-)

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tlhpsound
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Re: Regurgitator kit Build Thread

Postby tlhpsound » Sun Sep 16, 2018 9:19 pm

What is the purpose of adding mono caps there? As a stereo pair, is not it better that both have caps (or both don't)?

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Re: Regurgitator kit Build Thread

Postby Joe Malone » Sun Sep 16, 2018 9:32 pm

tlhpsound wrote:What is the purpose of adding mono caps there? As a stereo pair, is not it better that both have caps (or both don't)?


If you are powering them together from one power supply they share the caps anyway as they are just extra smoothing to the +/- rails. Feel free to cut the 1uF caps off or add 1uF to the other module either way it will not make any difference with NE5532A they are not needed at all.

When we used OPA2604AP which is no longer available we would add these caps as stabilize that very unstable that opamp.
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tlhpsound
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Re: Regurgitator kit Build Thread

Postby tlhpsound » Sun Dec 02, 2018 12:53 pm

If I wire a pair of 600 ohm/600 ohm transformers to the outputs of DAC, can I use a log volume pot of 50k or higher? Or I should still use a 5K to 10K pot? I like the effect of the transformer.

Joe Malone wrote:
tlhpsound wrote:OK. Thanks. I have another question. I ordered these kits as a make up gain for a stereo volume pot which I want to place after the DAC module. The application is a DIY car stereo using a Linux chip-on-the-board PC. I do not know the output impedance of the DAC. What would be the optimal impedance of the pot? I am looking at a 50k pot. Would this kind of configuration work?


A DAC will usually run 2k loads so a 5k to 10k log volume pot between the dac output and regurg +in should work perfectly with the regurg giving you makeup gain and balanced output.

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Re: Regurgitator kit Build Thread

Postby Joe Malone » Sun Dec 02, 2018 1:16 pm

tlhpsound wrote:If I wire a pair of 600 ohm/600 ohm transformers to the outputs of DAC, can I use a log volume pot of 50k or higher? Or I should still use a 5K to 10K pot? I like the effect of the transformer.

Joe Malone wrote:
tlhpsound wrote:OK. Thanks. I have another question. I ordered these kits as a make up gain for a stereo volume pot which I want to place after the DAC module. The application is a DIY car stereo using a Linux chip-on-the-board PC. I do not know the output impedance of the DAC. What would be the optimal impedance of the pot? I am looking at a 50k pot. Would this kind of configuration work?


A DAC will usually run 2k loads so a 5k to 10k log volume pot between the dac output and regurg +in should work perfectly with the regurg giving you makeup gain and balanced output.


Balanced input is twice the impedance so pot value can double but 50k log pot is a bit high and will change the log curve a lot. Keeping the pot low like 5k or 20k is better for the correct curve and lower noise.
Joe :-)

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