mutting transistors on the output of Marantz cd40 help!!!

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
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?
 

Attachments

  • mutting transistors.JPG
    mutting transistors.JPG
    140 KB · Views: 533
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.
 

Attachments

  • Picture 012.jpg
    Picture 012.jpg
    510.1 KB · Views: 498
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
 

Attachments

  • basic output.jpg
    basic output.jpg
    101.2 KB · Views: 487
  • basic IV out.jpg
    basic IV out.jpg
    32.4 KB · Views: 423
Last edited:
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?
 
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?
 
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.
 
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.
 
Take a look here. At the bottom of the page is a document I wrote for Brent (Fidelity Audio) relating to clocking the TDA1541. At the end of document is the exact circuit I use.

I made a mistake earlier, the CCS is connected to a positive supply (Just checked on my CDP to make sure). I run it from the regs on my bursons so the supply is +12v then via 4k7 and a 5k pot (multi turn). I set the meter to read millivolts and tune the DC offset to 0.

I note is that I always turn the CDplayer 1st then let it settle for few minutes before I switch my amp on. This way the offset settles before the amp is powered up.

You cant beat decent regs all round especially on the SAA7220 chip in this player...........enjoy :)
 
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.

I meant the effort you put in it thats nice.
icon7.gif

You are right the sound what is matter.
 
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


I've tried your modified circuit on one chanell. No basses at all. I think that filter stage has to stay where it is.
 
I meant the effort you put in it thats nice.
icon7.gif

You are right the sound what is matter.

Its just a test project, when (if) I reach all possible improvements ill put it in a nice box :). For sure ill choose a wood.
In this moment i like the sound, but there are still a lot off things to do.
I ordered 20 peaces of ELNA silmic II 100uF/35V just to try if that will change something. If not, ill try with Black Gates.
In general, this modified Marantz CD40 can fight against much more expensive players.
 
What is your exact circuit now?

You could have an impedance mismatch between the CD and amp. If this is the case, you should re instate the resitor to gnd as per your original circuit to see of this helps. Also, if you are using DC blocking caps, low value here can sometimes hold back the bass if the impedance is poorly matched.
 
.................... 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

To remove the de-emphasis circuit it is only necessary to remove the fet.
The other components are still part of the overall filter. Removing them all will alter the filter characteristics especially at the very top end.

Andy

.
 
Last edited:
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.