mutting transistors on the output of Marantz cd40 help!!! - diyAudio
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Old 11th March 2011, 06:39 PM   #1
GoranB is offline GoranB  Poland
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Default mutting transistors on the output of Marantz cd40 help!!!

I would like to skip the mutting transistors on the output of IC's, can someone tell me if those are transistors inside the red collored borders, and if it will be enough to unsolder R3678/100ohms and take the signal after the output cap 100uF?
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Old 11th March 2011, 07:02 PM   #2
danico is offline danico  Hungary
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Yes. That should be good. Although I didn't do it yet on mine cd.
I just started to swap the caps. Its sound great already.
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Old 11th March 2011, 07:34 PM   #3
GoranB is offline GoranB  Poland
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Originally Posted by danico View Post
Yes. That should be good. Although I didn't do it yet on mine cd.
I just started to swap the caps. Its sound great already.
I add an regulated PS on every possible IC, separated trafo for audio stage, separated rectifier and PS for TDA1541, also decoupled with 16 WIMA 220nF, separated PS for SAA7220, I tweaked the mechanism of the transport...for PS of LM833( Istill didnt changed them) i have Vishay low ESR caps 220uF/35V. ABout analog output stage im thinking to take signal directly from TDA1541 and to build an SE double triode tube preamp, but im still far from that.
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Old 11th March 2011, 08:18 PM   #4
UV101 is offline UV101  England
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Measure the DC on the opamp output before the blocking caps just before the red marked area. If there is no DC present, connect the output here.
If there is some DC, get yourself some 4.7uF MKPs or better to replace the green elco's and take the output from after the DC blocking caps.

I use a single burson opamp (1st stage shown in the diagram) with feedback filtering after my TDA and an adjustable CCS to set the offset to 0v. Then I don't need caps in line with the output. Also, you dont really need any of the DEEM stuff in parallel with the 1st opamp filter circuit so you can remove all that if you want!

1 pic shows the original circuit adjusted and 1 shows the same but with better components and all the other bit removed
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File Type: jpg basic IV out.jpg (32.4 KB, 341 views)
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Old 11th March 2011, 08:27 PM   #5
GoranB is offline GoranB  Poland
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Quote:
Originally Posted by UV101 View Post
Measure the DC on the opamp output before the blocking caps just before the red marked area. If there is no DC present, connect the output here.
If there is some DC, get yourself some 4.7uF MKPs or better to replace the green elco's and take the output from after the DC blocking caps.

I use a single burson opamp (1st stage shown in the diagram) with feedback filtering after my TDA and an adjustable CCS to set the offset to 0v. Then I don't need caps in line with the output. Also, you dont really need any of the DEEM stuff in parallel with the 1st opamp filter circuit so you can remove all that if you want!
I already meassured and there is some DC before the MUSE Nichicon output caps. I have some MKP's - 22uF maybe it will be good to replace the nichicon's. It would be the best withou caps. Can You send a schematics of your modifications?
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Old 11th March 2011, 08:27 PM   #6
UV101 is offline UV101  England
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I edited the previous post to include schematics :-)

Cant find the one with the CCS for 0v DC offset right now, but its just injecting the -15v via a 5k (I think) pot onto the output pin of the TDA. Make sure you start to adjust with the pot set to 5k!!!!
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Last edited by UV101; 11th March 2011 at 08:31 PM.
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Old 11th March 2011, 08:28 PM   #7
GoranB is offline GoranB  Poland
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Upppsss... You already send
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Old 11th March 2011, 08:38 PM   #8
GoranB is offline GoranB  Poland
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Quote:
Originally Posted by UV101 View Post
I edited the previous post to include schematics :-)

Cant find the one with the CCS for 0v DC offset right now, but its just injecting the -15v via a 5k (I think) pot onto the output pin of the TDA. Make sure you start to adjust with the pot set to 5k!!!!
If I understood You well...I should add an extra negative regulated PS in series with 5K precisse pot on the DAC analog outputs and it will set the output of op amps on 0V?
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Old 11th March 2011, 09:03 PM   #9
danico is offline danico  Hungary
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Nice job on the cd. I'm sure it will sound great with the tube preamp.
I have the DAC-END from Quanghao waiting in my closet to be build. I cant wait to finish it.

I only plan to build a separate Reg for the 7310 and 7220. Decapling the dac is not finish yet, waiting for parts.
I tried OPA627 but it oscillated so I put back the old lm833.
Maybe I need different resistor and cap value at the first stage.
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Old 11th March 2011, 09:14 PM   #10
GoranB is offline GoranB  Poland
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Quote:
Originally Posted by danico View Post
Nice job on the cd. I'm sure it will sound great with the tube preamp.
I have the DAC-END from Quanghao waiting in my closet to be build. I cant wait to finish it.

I only plan to build a separate Reg for the 7310 and 7220. Decapling the dac is not finish yet, waiting for parts.
I tried OPA627 but it oscillated so I put back the old lm833.
Maybe I need different resistor and cap value at the first stage.
It doesnt look good at all but its not for eyes but for ears . I tried a several materials for top and bottom covers. The sound is best without top or bottom covering (My subjective impression). Till now it sounds very nice, huge amount of details and deeeeeep sound stage. Im using tube preamp and power follower SE design A class (one FET) like a "power amp". No NFB in preamp and amp. Both are a class A, SE topology.
The best improving of sound of the CD player was the removing the all those plastic parts from cd mechanism. Also screening the wires from display controller. I did it with alu-folly and after i isolated it. The two green fat wires on the picture are ground for the shilds of alu-folly.
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