California Audio Labs Gamma upgrades?

G · 10th June 2004, 01:14 PM

Hi all,

I have had a CAL Gamma dac sitting on a shelf for about a year. Yesterday I hooked it up and found that the sound from my Parasound CDP 1000 player is better. What can I do to improve this unit?

tttking · 19th December 2005, 03:56 AM

If you have not gotten rid of your Gamma DAC and you are handy with sodering gun, here are what I have done to substantially improve the sound of my Gamma DAC.

1. Replacing the pair of TL071 OPAMPs with OPA627s and conecting one 2.7K resistor between pin 4 and pin 6 of each OPA627. I have also tried OPA124, AD743 and AD829. I prefer the OPA627 by a large margin.

2. Replacing the pair of ouput capacitors and the pair of OPAMP decoupling capacitors with ELNA Cerafine 220uF 16V capacitors from http://www.welbornelabs.com/elna.htm . You may also condider Black Gate N type capacitors. They are the favorate of many advanced DIYers, though I do not have personal experience with them.

I am quite happy with the sound of my Gamma DAC now. Hope you will try some modifications and have fun.

BTW, I use a 6N1P SRPP tube pre amp and a DOZ class A FET power amp.

pepolino · 3rd February 2011, 03:34 PM

hi guys, I know this is an "ancient" topic, but I am doing this upgrade on a Gamma which I had for free from a friend of mine, and I wonder about the reason why there are the two 2,7K resistors between pin4 and 6 of the OPA.
Can someone please explain that? I love music, but sadly I'm not so much into electronics...

tttking · 25th June 2011, 06:42 PM

Hi Pepolino:

2.7 kohm give the Opamps 4.4 ma of current at zero signal, allow it to run "kind of class A" amplification. The original OP627 is extremely accurate but sounded sterile. With the 2.7k it is much more musical.

I apologize for the late answer. I do not browse the board often.

pepolino · 29th June 2011, 10:04 AM

Thanks, TTTKING

do you have also an idea about the reason why the volume is lowered now compared with the original OPA? It is not a small difference, it's really a very noticeable difference between the two! I have to rotate volume knob up to 3/4 to listen to same level that I was getting at 1/4 before!

10th June 2004, 01:14 PM	#1
G diyAudio Member Join Date: Apr 2002 Location: Belleville, IL.	California Audio Labs Gamma upgrades? Hi all, I have had a CAL Gamma dac sitting on a shelf for about a year. Yesterday I hooked it up and found that the sound from my Parasound CDP 1000 player is better. What can I do to improve this unit? __________________ Gavin

19th December 2005, 03:56 AM	#2
tttking diyAudio Member Join Date: Nov 2001 Location: Los Angeles	Gamma DAC Upgrade If you have not gotten rid of your Gamma DAC and you are handy with sodering gun, here are what I have done to substantially improve the sound of my Gamma DAC. 1. Replacing the pair of TL071 OPAMPs with OPA627s and conecting one 2.7K resistor between pin 4 and pin 6 of each OPA627. I have also tried OPA124, AD743 and AD829. I prefer the OPA627 by a large margin. 2. Replacing the pair of ouput capacitors and the pair of OPAMP decoupling capacitors with ELNA Cerafine 220uF 16V capacitors from http://www.welbornelabs.com/elna.htm . You may also condider Black Gate N type capacitors. They are the favorate of many advanced DIYers, though I do not have personal experience with them. I am quite happy with the sound of my Gamma DAC now. Hope you will try some modifications and have fun. BTW, I use a 6N1P SRPP tube pre amp and a DOZ class A FET power amp. __________________ Tim King

25th June 2011, 06:42 PM	#4
tttking diyAudio Member Join Date: Nov 2001 Location: Los Angeles	Hi Pepolino: 2.7 kohm give the Opamps 4.4 ma of current at zero signal, allow it to run "kind of class A" amplification. The original OP627 is extremely accurate but sounded sterile. With the 2.7k it is much more musical. I apologize for the late answer. I do not browse the board often. __________________ Tim King

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3rd February 2011, 03:34 PM	#3
pepolino diyAudio Member Join Date: Mar 2009	hi guys, I know this is an "ancient" topic, but I am doing this upgrade on a Gamma which I had for free from a friend of mine, and I wonder about the reason why there are the two 2,7K resistors between pin4 and 6 of the OPA. Can someone please explain that? I love music, but sadly I'm not so much into electronics...

29th June 2011, 10:04 AM	#5
pepolino diyAudio Member Join Date: Mar 2009	Thanks, TTTKING do you have also an idea about the reason why the volume is lowered now compared with the original OPA? It is not a small difference, it's really a very noticeable difference between the two! I have to rotate volume knob up to 3/4 to listen to same level that I was getting at 1/4 before!

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