Parallel TDA1541A non-o/s DAC Kits

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#62
parallel Tda1541a kits

hi all,

pls see the test print monther board.

its made by OFC SF4 PCB.

thanks

thomas
 

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#65
Re: Re: Parallel TDA1541A non-o/s DAC Kits

Kuei Yang Wang said:
Best is direct coupled, filterless (but use Anti Sin(x)/(x) Filter), transformerless 7308 (Common Cathode stage per channel), biased directly from the -2mA offset of the DAC at a few 100mV, low anode voltage, choke or CCS load. Watch linearity though, this arrangement is a bit critical, the Valve operates near zero bias. But the short chain of: Chip -> Resistor -> Grid (cathode direct to ground) -> Cap from Anode to output works best from where I stand.
Click to expand...

1) What voltage for anode?
2) What value for choke?
3) What value for gridstop resistor?
4) Can 7308 be substituted by E88CC? I have a pair of Mullards.

Ciao.
 
#66
parallel Tda1541a kits

hi anthouy,

thanks for your interest.

I need two week to test.

this test print I added more functions which compare with the standard specification that at first posted on this forum.

1. include I2S input which was very close the CS8414 to prevent the data error during passing the message.

SYN-SCK-SDATA.

Reclocking input also reserve for my coming reclocking parts.

I was waiting for my japan friend posting lower than 30PPM crystal to me to build the reclocking parts.
Diyer can make choice use or not.

for more information, pls visit.

http://www.sakurasystems.com/

2. added one dip.switch.

for setting for different mode.

syn mode or aysyn mode.

3. The T1 space on the PCB at first I deside come with the RS Pulse (H.F.) 75ohm input transformer. Ratio is 1:1.
But recently I received some news & due to I had links with japan many brand audio transformers.
I received that Tamura had one new developed Pulse transformers which design for the digital interface for professional audio equipment as prescribed in EIAJ standards.
the band width is more width than RS.
Tamura from 100Khz~6MHz. Its made by Amorphopus core.
I was waiting for the sample.
If the price that japan offer to me is good. I will use into the kits.

ciao, do U agree my choice.

thanks

thomas

www.diyaudioicraft.com
 

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#68
parallel Tda1541a kits

hi Anthony,

I had not

PE-65612 (Pulse Engineering)
67125450 (Schott Corporation)

on hand. So I cannot test the result between them.
I only the silver wire from audio consulting use for D/A to compare. This small trans I buy two years ago when euro still low.

http://www.audio-consulting.ch

But If U like me to choose. I still will choose Japan trans.
For example, The magnetic floating train still japan will be the best. Can floating up to 1cm.
The tamura small da trans was made by amorphous core.
But the PE-65612 & the 67125450 had said any material to make the core. so I think if the price is reasonable, I will choose tamura.
certainly it must depend to the price.

anthouy, the PCB is design by myself, the rev.1.1 is coming.
Give me some time, i will only produce the best items.

When this pcb produce will gold in colour.
New version will include the AD844 into it.

thanks

thomas
 

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#69
parallel Tda1541a kits

hi,

yesterday I got another sample for the power transformer which i prepare use in the PCB.
I wish use one power transformer to supply the digital part of the PCB. Another power transformer was use to the tube output stage. (6X4 rectifier tube, 6DJ8, EC8010 or 6C45). Due to 6c45 & EC8010 run with approx 20ma per tubes & total tube PCB will contain 3 filament. I suggest seperate power transformers.
Do u agree?

Can anyone advise to me that use EI, Round, or this r-core power transformer will better in the digital circuit??

thanks

thomas
 

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#70
Hi Thomas, please have them wound with 230V primaries ! In Europe we have 230V AC for at least 15 years now but some transformer manufacturers apparently still think we have 220V AC. In the UK they used to have 240V AC but I think they've gone to 230V AC too. Anyhow, 230V primaries and a 240V tap is not a luxury. 240V might come handy when the net voltage is higher than specified. Sometimes it's 237V. With 220V wound toroids this can cause humming and overvoltage at the primaries.

Please inform the transformer-manufacturer of the fact that Europe has 230V net voltage. AFAIK there is not a single country left with 220V.
 
#71
parallel Tda1541a kits

hi paul,

thanks for your advise.
I prepare to produce three types of different pri volatge,
220V,117 & 230V.
than I will more easy to maintain the sec. voltage less fragile within 2%.

Until right now. I prepare two power transformers which will use in the kit.
1. Seperate winding for digital & Analogue part use.
2. HV had 220~0~220 which for 6X4 receifier tube use to supply the HV to the tubes.
6.3V 2V For x4
6.3V 3A for 6C45,Ec88,86,8010 or 6C45.

I use two days to finish the test print with all the parts.
pls see the dale, holco, Simens MKT, Philips MKP. OS-con Elna etc.

Hope this High Price /cost ratio da board more diyer will enjoy.

the tubes output board is coming, I would like to tell U the laterest print will all electroplate 1 micron gold to make sure the digital signal run more smooth.

this is all my best can do it.

thanks

thomas

www.diyaudiocraft.com
 

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#72
parallel Tda1541a kits

hi all,

the large lots of the philips Metal film was arrived. The film cap will use in the TDA1541A de-coupling. Kit will follow with this cap.
power transformer was coming too......



thanks

thomas
 

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#74
Pls see the new parts will use in the version II DAC.

P.S. The new version II will be the funish version.
It means U not need to solder any parts in the DAC PCB.
But...... the new tube buffer PCB U must funish by yourself.
The estimate time is 2 hour only.

Point of improvement for the new DAC.

Added OPA627 for the I/V.
Use Pulse enginneer digital input trans into PCB.
PE-65612.
Can use AES input.
Opinional re-clock PCB.

tube Buffer upgrade with battery bias, can use 6X4. EZ80,81 or WE412a.

thx


thomas
 

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#79
Dear authony & peter,

Do U had any information for ML PE digital input!!

I can only search PE had 65612 & 65812, one is SMD & another is
DIP.

Any information about the 62251, Is this use for XLR input(110ohm)??

If yes, I need this one because I was planning added this one into it.

Pls see there-clock for the TDA1541a.

more PCB as SMD change to DIP, Single OP-change to dual -op-amp. will fit together.


thx

thomas
 

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#80
Hi Thomas

Several companies make replacement parts for PE 62251. Check out here:

http://www.rhombus-ind.com/pt-cat/rf-2.pdf

T-12007 is the one. The bandwidth is only 50MHz. Pretty surprised ML would choose this part. After experiments, I decided to stick to 2X 10000pf silver mica instead. Currently I am using CDEs. Will try some Russian military surplus type. Eventually I will switch to Shoshins.

Can I buy the reclocking board and the battery bias thing for my kit? BTW, be sure to use 74VHC, avoid 74HC.

For the decoupling caps, I found BG's NX .47 HiQ is the best (thanks, Peter!). I parallel it with the .01uf SPP cap here:

http://home.kimo.com.tw/ucccap/ucccap.htm

The sound is more transparent and has better resolution now.

Just ordered 4 Siemens .47uf MKVs and two .47uf MCap silver/oil. Will try them on the output coupling. Should be a fun experiment.


-finney
 
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