TDA1305 Requirements

[PC91]

Hi diyers, i don't know if its the correct forum so correct me if not.

Some months ago i've got a Technics SL-XP5, inside there's a dull sounding PCM55HP multiplexed for stereo and a very noisy preamp and headphones stage.

So, as technology evolved and got cheaper i'm completely rebuilding the audio stage.
By now i could get audio using a TDA1543 and also with an CX23034 digital filter and a CX20152 DAC.

Now the final goal is to build it using a spare TDA1305T from an old PCA80SC Scsi CD Drive, so as far as i understand the datasheet the pins should be:

1: VDDa : to 5v
2: VSSa : Ground
3: Test1: Ground (LOW for select LSB Fixed 16 bits)
4: BCK: to DSP
5: WS: to DSP
6: DATA: to DSP
7: CLKS1: LOW for select LSB Fixed 16 bits
8: CLKS2: HIGH for select LSB Fixed 16 bits
9: VSSd: Ground
10: VDDd: to 5v
11: Test2: Ground
12: SYSCLKI : ????? (256fs??)
13: NC
14: NC
15: VSSd: Ground
16: SYSCLKO: NC
17: DEEM1:LOW (for disable)
18: DEEM2: LOW (for disable)
19: MUSB: LOW (for deactivate)
20: DSMB: LOW (for deactivate)
21: ATSB: LOW (for deactivate)
22: VOL : to Headphone amp
23: FiltCL: Filter capacitor
24: FiltCR: Filter capacitor
25: VOR: to Headphone amp
26: Vref: Capacitors and ground
27: VSSo: Ground
28: VDDo: to 5v

On BOLD is what are my doubts, specially SYSCLKI i'm not sure what the DAC is expecting there and how are the tolerances, some IC only require that SYSCLK to be higher than BCLK and is good. So, i listen to your wisdoms on how to proceed.

Thanks!

 

[Ciu]

Hello !

May be, you could find something in the Cambrige DacMagic Manual, with same topology , 2 TDA1305 inside .

 

[PC91]

Thanks Ciu, but still can find anything that throws me light at the issue

 

[PC91]

Success!!! after a lot of struggle an trial and error now my technics sl-xp5 is soundig terrific with its new tda1305t, it was not possible to completely eliminate the original audio stage, i have to keep the MN6618 digital filter since it made corrections to the clock necessary for the tda to work. So if anybody wants to hook up and TDA1305 to any technics or any device that handles standard EIAJ Serial digital audio at 16bits 44.1khz.. here is my wiring method:


1: VDDa : to 5v
2: VSSa : Ground
3: Test1: Ground
4: BCK: to DSP
5: WS: to DSP
6: DATA: to DSP
7: CLKS1: Ground
8: CLKS2: to 5v
9: VSSd: Ground
10: VDDd: to 5v
11: Test2: Ground
12: SYSCLKI : 16mhz input
13: NC
14: NC
15: VSSd: Ground
16: SYSCLKO: NC
17: DEEM1:Ground
18: DEEM2: Ground
19: MUSB: to 5v
20: DSMB: Ground
21: ATSB: Ground
22: VOL : Left output
23: FiltCL: Filter capacitor
24: FiltCR: Filter capacitor
25: VOR: Right Output
26: Vref: Read Below
27: VSSo: Ground
28: VDDo: to 5v


So… BCK, WS, DATA And SYSCLKI must go to the Digital Filter or DSP, on MN6618 is:

BCK: Pin 19
WS: Pin 15
DATA: Pin 20
SYSCLKI: Pin 34

That same applies with any other dac accepting EIAJ, TDA1543A, TDA1544, Some Burr Browns, AKM, Etc…

As for the output pins… TDA1305 has integrated OPAMP, and since i’m using a portable i can directly connect headphones to the DAC chip thus choosing the correct capacitors was trivial, for coupling the output i used 100uf OScons, and for filter pins i choose polyester caps, the smaller the better, this caps are really important since they make a filter and if are not really good, they filter too much.

For Vref, i found excelent results with an 100uf OScon and a small tantalum caps, also added a polyster cap in parallel but the result was the same.

Is a extremately good practice to use a dedicated Voltage regulator with good caps feeding the dac and digital filter to achieve cleaner results, i used 470uf OScon and 2.2uf tantalum in parallel.

Okay, any questions?

 

[rockerxx69]

Twin differential dacs

Hallo. I want to by pass my twin differential tda 1305, op amps in balanced mode (Cambridge DAC magic ll mkii ) and feed a tube balanced analogic stage. Where do l find signal +,-, ground for channel??? Thanks

 

[PC91]

You have to check the schematics for it to see how it's made, still lampizator made some mods on it DACMAGIC Cambridge tubed DAC player TDA1305

 

[rockerxx69]

That s where I started, using a later time Balanced lampizator PCB tube analog stage, It was assembled by a guy abroad, first problem was that it had no 'slam' no speed, no up in yer face sound, so I contacted Lampizator and he kindly told me the components to change from his original project, so I reached finally the sound that I wanted, second problem is noise on the XLR outputs, which I use the most, RCA are absolutely silent, we ll have to raise the main PCB and see where the pins have been used, I want to by pass the in-built chip op amps and feed straight to the tube amp board-yes he talked (lampizator) on such a modding but not shown how and where get the balanced R and L signals.

 

[PC91]

When i used the 1305 i ended using the internal OPamps, after reading a lot on the tda1549, that is mostly the same, people concluded that the Iout was not meant to be used since removing the OPamps gave distorted sound, it was necessary to use some sort of OPamp in order to became stable, still u can add better opamps. the RCA surely got disconected to avoid inducing noise on the new xlr circuit, you should check how it was done

 

[rockerxx69]

tubed lampized dac

I went to a technician, I m not, as I stated earlier I do have hum on xlr outputs, rca are absolutely silent, the sound is great, we opened the dac, it was Lampized overseas, the guy removed the ops completely and soldered at the relais, we guessed, see photos, my actual tech did some new cabling and soldering, basically the signal s been taken from that point in the PCB-I ll go test it I guess it will be the same hum...has the signal been taken rightly??? thanks

 

[PC91]

i'm having a hard time trying to see where he took the signal, also removing the OPAmps is OK, you isolate the circuits, still looks like he used the RCA for something since it has wires to it.
About the hum... is maybe that the tube heaters are powered by AC and that is inducing humm

 

[rockerxx69]

The RCA goes as well in the PCB balanced audio tube stage. RCA out has not got hum !

 

[rockerxx69]

It has been lampized both on rca in--out than xlr in-out, rca out is silent and a great sound, xlr has got hum---

 

[rockerxx69]

Hallo ! We guessed he took signal from (orange ) bal out + and bal out -

 

[PC91]

ignoring whatever he made if you got hum in the XLR in general may be due to the lack of ground or maybe misconecting the negative signal and the ground one, you can easily check that with a multimeter or if you have a cheap xlr laying around you can test by swapping them on the XLR jack. Also can be a problem of the lampization process in the XLR part, maybe a loose wire or capacitor

 

[rockerxx69]

High gain

This Lampizator tube stage was low in gain, l asked Lampizator how to rise gain. He sent me 4 resistors and 4 caps, they have been soldered and replaced the old ones. Yes l ve got the sound l wanted, Absolutely fantastic, live, in the room, presence, .......that s on the RCA out, l guess since we rised gain a lot, XLR simply being 6 dB more just intercept, hum and noise from the tubes, it s not a problem of ground .........you put the answer in my hear l guess !!!!!!

 

[Alfanijs]

Hi, I just started modding a Cambridge Audio DAC3 and came across this thread a bit late. Hope somebody's still there.
From your diagram in message #13 it appears you have connected your Lampizator to the output AFTER the op-amp stage. This is not ideal and sort of defies the reason for using a tube buffer stage! The best location to pick the signal is from DAC pins 22 and 25 (VOL or VOR resp.), just before the 680 Ohms resistor. I would leave the first 1nF cap in place as it acts as a 1st-order LP filter. You can lift the resistors or leave them in if you want to keep the original outputs for comparison. I have just taken the signal from here via a 2.2uF film cap directly to the output, and the improvement is huge. Much less harshness and sibilance. No need for tube stage...

 

[rockerxx69]

Can you tell me from my posted photo, where to connect it ??? Dont look at the schematic, look at the photo, I asked my technician to take signal before op amp, otherwise there would be no reason.

 

[Alfanijs]

Can you tell me from my posted photo, where to connect it ??? Dont look at the schematic, look at the photo, I asked my technician to take signal before op amp, otherwise there would be no reason.

Hi, it is difficult to tell exact position from your photo (post #9) since I have not got the unit in front of me and I don't have a service manual unfortunately. However it looks like your technician tapped the signal from just before the opamps, which means that they are not in your audio path. Good! In my opinion it would be better taking them from pins 25 and analog ground for Single-Ended signal (or pins 22& 25 for balanced out).

As you can see I took the signal from the top side, easy access for testing without taking out the PCB. Grey wires are grounds.
Hope this helps!