TDA1541 - Valve analog output stage ( Musical Fidelity DIGILOG )

[Martynka]

Hi,

I want to write something about "lampization" of my TDA1541. Maybe someone trying to find some info without result. I tried and was not easy... but I done it.

I have two TDA1541 in my system. One is Arcam Alfa 5 Plus CDP, second is Musical Fidelity DIGILOG.



I completelly moded my ARCAM ( NOS, reclock, power supply, decoupling, opamps ), now sounds great.
The same I started with MF, but I need more - I NEED VALVE INSIDE.

I done it and in my opinion it is the best DAC that I heard ever.

I used scheme from Fikus "Lampizator" site with 6N16B in SRPP mode. It is really good solution if you dont have a place inside.

I bought and used:
- transformer 200V, 6,3V
- power suplly with voltage regulator
- 2 x 6N16B
- few resistors
- few universal PCB.

1) First, I moved the original transformer to make room for a new one and I added the second.



2) I done beta version of my valve system to check all parameters and adjust everything ( anode V, BIAS )



3) I built final version of my tube system and mounted it inside DIGILOG



Like you see I soldered tubes to precision DIL sockets. It is because now I can change valves without soldering.

4) I found place for my power supply ( I had to mount it upside down and move the potentiometers to the bottom of the board to access voltage regulation )



5) I changed output caps.



Now I will answer some questions that I will ask by myself

- Why I used regulated power supply not a diodes bridge ??

Because I can change anode voltage.
First - In Lukas Fikus project was 200V. In my opinion it is too high. I checked on my beta system sound with anode voltage from 220V to 140V ( I can change it with pot ). The best sound was from 150V and I left this. Second - I tried with 6021 Mullard too and 200 V is too much for this tubes (160V max)

For heaters I could use 6,3V AC but in my power supply I have two circuits. One for anode, second for heaters and I used 6,3V DC ( I can regulate it too ).

- Why I changed output capacitors ??

In SRPP the output impedance is sensitive to too low impedance of the next stage, the amplifier works best when the next stage is matched to the impedance of the SRPP system (it is not lower). I had 1,6 uF - now I have 0,5 uF. Another reason was that old Mundorf Evo Alu Oil sounded excellent with opamps but with tubes start play to high and without details. New Mundorf Supreme solved this problem.

- How high is the BIAS value in my system ??

For 6N16B in catalogue is about 6,3 mA, in this point I had to much distorsion, I adjusted it to about 2,5 mA with 620R cathode resistors.

- What type of DAC is TDA1541 - current or voltage ??

TDA1541 is current type and we need 80ohm converion resistor.

- From where I stole the output signal from the TDA1541

I stole it directly from 6 leg of TDA for right chanel and from leg nr 25 for left chanel.



On bottom photo you can see also my tantalum decoupling caps. On the top I have WIMA too



all of the pairs are 550nF and last two pairs 2,2uF.

I have also modified power supply for TDA - discrete voltage regulators:



and I have NOS reclock mode too



It was really easy to done. If you need scheme strictly for TDA1541 I can put it here.

I hope that maybe someone after read it want to do the same. I have second set for my Arcam Alfa and next week probably I will start this project one more time

 

[mbz]

I have 2-3 TDA1541 units set aside for this kind of project. Plan to use relays/timers for graceful
start up of the valve mostly for longevity

 

[Martynka]

Plan to use relays/timers

I have it built in my power supply:
- slow build-up of the heaters voltage
- delayed anode voltage switching
- and I can use timer for delayed activation of the DAC output

3 reasons more why I use this power supply.

 

[Martynka]

Something about subminiature tubes:

https://www.effectrode.com/knowledge-base/subminiature-tubes/

 

[adam33]

Hi,

I want to write something about "lampization" of my TDA1541. Maybe someone trying to find some info without result. I tried and was not easy... but I done it.

I have two TDA1541 in my system. One is Arcam Alfa 5 Plus CDP, second is Musical Fidelity DIGILOG.

I completelly moded my ARCAM ( NOS, reclock, power supply, decoupling, opamps ), now sounds great.
The same I started with MF, but I need more - I NEED VALVE INSIDE.

I done it and in my opinion it is the best DAC that I heard ever.

I used scheme from Fikus "Lampizator" site with 6N16B in SRPP mode. It is really good solution if you dont have a place inside.

I bought and used:
- transformer 200V, 6,3V
- power suplly with voltage regulator
- 2 x 6N16B
- few resistors
- few universal PCB.

1) First, I moved the original transformer to make room for a new one and I added the second.

2) I done beta version of my valve system to check all parameters and adjust everything ( anode V, BIAS )

3) I built final version of my tube system and mounted it inside DIGILOG

Like you see I soldered tubes to precision DIL sockets. It is because now I can change valves without soldering.

4) I found place for my power supply ( I had to mount it upside down and move the potentiometers to the bottom of the board to access voltage regulation )

5) I changed output caps.

Now I will answer some questions that I will ask by myself

- Why I used regulated power supply not a diodes bridge ??

Because I can change anode voltage.
First - In Lukas Fikus project was 200V. In my opinion it is too high. I checked on my beta system sound with anode voltage from 220V to 140V ( I can change it with pot ). The best sound was from 150V and I left this. Second - I tried with 6021 Mullard too and 200 V is too much for this tubes (160V max)

For heaters I could use 6,3V AC but in my power supply I have two circuits. One for anode, second for heaters and I used 6,3V DC ( I can regulate it too ).

- Why I changed output capacitors ??

In SRPP the output impedance is sensitive to too low impedance of the next stage, the amplifier works best when the next stage is matched to the impedance of the SRPP system (it is not lower). I had 1,6 uF - now I have 0,5 uF. Another reason was that old Mundorf Evo Alu Oil sounded excellent with opamps but with tubes start play to high and without details. New Mundorf Supreme solved this problem.

- How high is the BIAS value in my system ??

For 6N16B in catalogue is about 6,3 mA, in this point I had to much distorsion, I adjusted it to about 2,5 mA with 620R cathode resistors.

- What type of DAC is TDA1541 - current or voltage ??

TDA1541 is current type and we need 80ohm converion resistor.

- From where I stole the output signal from the TDA1541

I stole it directly from 6 leg of TDA for right chanel and from leg nr 25 for left chanel.

On bottom photo you can see also my tantalum decoupling caps. On the top I have WIMA too

all of the pairs are 550nF and last two pairs 2,2uF.

I have also modified power supply for TDA - discrete voltage regulators:

and I have NOS reclock mode too

I would like the schematic for Nos in place of SAA7220 as I am currently modifying a Marantz cd75 mk2.

It was really easy to done. If you need scheme strictly for TDA1541 I can put it here.

I hope that maybe someone after read it want to do the same. I have second set for my Arcam Alfa and next week probably I will start this project one more time

I

 

[Martynka]

I

Something wrong with my hosting. They replace servers. Should be ok after Wendesday.

 

[nerdorama]

Why not just upload the pictures into the AK post? Then they won't go away.

 

[Martynka]

Why not just upload the pictures into the AK post?

Should be work about 4 hour. When my hosting run again I will download photos and upload into post.

 

[adam33]

Could you put the schematic for the reclock on here now the server is back working OK.

 

[Martynka]

Could you put the schematic for the reclock

I use this ( it is not my scheme ) :

 

[adam33]

Thanks, I'm going to be attempting to etch a double sided board and build it with
soic ICs and 0805 resistors. I've only etched a double sided board once before.

 

[Martynka]

My friend love my MFD and bought the same. My is early model his is 2 years later. Inside are different components, it looks like MF used cheaper parts in later production
. His model is original without Digital out ( monitor ), RCA socket is on place but not connected and without relay.

My after big mods and originally:



I done lampization one more time. This time with Siemens ECC81.




and like always few changes near TDA1541.



Now I listen and compare both types of valves.



and I prefered my 6N16B and another russian 6N2P, I tried it on DIGILOG too:

 

[Martynka]

Update:

I love sweet mids from 6N2P-W with center of sound stage, and I love high definition, analitics sound from 6N16B-WI. Now I mixed both and have first stage on 6N16B and second stage on 6N2P. GREAT !!!