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Old 27th July 2004, 07:42 PM   #1
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Join Date: Jul 2004
Location: Hong Kong
Talking // TDA1541A PCB already

Dear all,

First of all. I would like to say sorry to Pedja because my design of this KIts which use AD844 OP-amp output stage was samilar to his design. Although the working condition, selection of chips
Pedja use J-fet, I use regulator IC was different. But the circuit design is similar. After the judgement of Jean-paul( moderator). The previous thread was closed & I can not amend any informations to the 18 buys of this kits.

To prevent for any or further agruement. The C board of my PCB will not further sold to any diyers. If U like the AD844 OP-amp output stage. pls ask for pedja, But Pedja's design which compare to me had some different. He use one TDA1541a but I use Two,working in parallel condition. The Best that I can was I think My PCB was one of the Best that in DIY DAC.

For My design pls visit.

http://johnson.tmfc.net/audio/file

The AD844 Schematic was still in this file. But this is for your reference only. I WILL NOT PROVIDE ANY PCB OR SUGGESTIONS FOR AD844.

The multiple output stage for different tubes was my design.

Also, I will post my new deisgn for the RE-clock circuit in this forum first to prevent any agruement as previous THAT involve the copyright with others.

At last I would like to say that my design or kits will not assume EARN MONEY. I only hope to PROVIDE the BEST Price/cost ratio to build kits to DIYERs.

An excellent circuit need high quality parts, otherwise cannot perform its really condition.

Photos shows is the previous photos about the full look of the DAC.

I still test some parts for improvement. I will continous amend it.

thanks

thomas
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File Type: jpg tda1541a dac kit fully funish..jpg (39.7 KB, 4843 views)
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Old 28th July 2004, 07:54 AM   #2
moamps is offline moamps  Croatia
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Location: Croatia
Default Re: // TDA1541A PCB already

Quote:
Originally posted by tube-lover
Although the working condition, selection of chips
Pedja use J-fet, I use regulator IC was different.
Hi,
That is correct. I don't know what was your first intention (IC or FET cs) but on your schematic IC 7805 is designated as Q not U what is strange.
Design with any CS and AD844 is obviously Pedja's IP on this board what is also strange to me.
One moderatorís clarification of this incident will be nice.
But who am I to ask .......

Regards
Milan
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Old 28th July 2004, 05:39 PM   #3
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Join Date: Jul 2004
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Talking //TDA1541A PCB Already

moamp,

thanks for your comment, so I cancell the AD844 already & advise any questions directly ask to pedja.

We all are diyer, we love diy. Not like in this level or question ( similar design) cost so many agruement.

This several days I test something about my kit I would like to amend is the tube Buffer PCB's filament regular Heat sink must added large for 4 Cm Height. Unless U use the AC to small tubes.
If U use the High efficiency Speaker as AER or Lowthers.( I use Philips 9710M) U try to double the filament 6.3V to 12.6V than use diode to rectify. its ~17V than use LM317 to regulate. But it need drop ~10V. The heat sink will very hot. So change to large heat sink will more stable.

I was testing the effect of NON-polar caps which will effect on the circuit.

I was the dealer of Japan Elna caps, so I can maintain a reasonable price to resell. So it means the diyer can use this non-polar caps in very good price.

thanks

thomas
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Old 31st July 2004, 03:01 AM   #4
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Location: USA
My own progress with Thomas's DAC kit is attached -- currently planning to use the infamous AD844 board for the output and build the tube board later. Gotta buy some trannies first.
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File Type: jpg kit.jpg (95.6 KB, 3981 views)
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Old 31st July 2004, 03:25 AM   #5
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Great work Strohmie!
I received the PCB/kit already but I haven't started yet. I was surprised by the quality of the PCB and how strong it is. This black PCB is cool...
I think I will go for the 6DJ8 tube option instead of the AD844.
I am thinking about changing all 28 decoupling caps to MKP 0.47uf, any idea of upgrading??
Cheers.


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Old 31st July 2004, 05:53 AM   #6
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The only thing I'm personally planning on upgrading is the pulse transformer, which I'll probably replace with a Lundahl LL1572 (I think the LL1566 that Thomas mentions as an upgrade is discontinued). It's much easier to upgrade one tranny than 28 caps.

Meanwhile I'm just hoping I didn't fry the CS8414 while installing it -- my Rat Shack soldering iron wasn't exactly specifically designed for such things.

I accidentally crushed one of the SMD caps, so that definitely needs to be replaced too. Thomas was kind enough to send two extras with my kit, but my mother was kind enough to vacuum them up after knocking them off my table.

Back to work.
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Old 31st July 2004, 06:04 AM   #7
Coulomb is offline Coulomb  England
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I am still waiting for my kit, meanwhile I have been looking at the AMVECO transformers. I am having trouble finding a 210-0-210 transformer for the tube stage, lots of single secondary 210 VAC, but dual, no luck yet. Any ideas other than running two transformers and tieing them together?

Regards

Anthony
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Old 31st July 2004, 10:35 AM   #8
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Default up and running

Got my kit running last night, pretty much without issue. I have used the AD844, as I'm down a few pieces to complete my intended o/p stage, which is the 6c45pi se config.

I think the 844's sound a bit electronic, particularly compared to my Sowter 8347 transformers, which I have on my own prototype board, but there hasn't been any burn in as yet. Great bass integrity though, however the image is a little recessed.

I must say I agree that the pcb quality is excellent, one of the best I've ever seen, and will be robust enough to allow tweaking on a grand scale.

Incidentally, there is a small labelling error on the TDA1541A board, which will cause a problem if you, like me, want to use I2S.

pin 1 says data, it should be on pin 5
pin 3 says Serial clock, and it is correct
pin 5 says Syn, and it should be on pin 1

I think the schematic is right, it's just the screen printing.

My experience of soldering the 8414 was a litle nerve jangling, even with a super fine tip- fortunately, it's a pretty robust chip...keep some desoldering wick close by!
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Old 1st August 2004, 09:34 AM   #9
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Talking //TDA1541A PCB Already

dear Tim & Strohmie,

I was very happy to hear that U all satify the PCB.

Actually I paid more effort about this.

There was a small amend about the kit.

1. the tube buffer need a little re-work.
pls check my website or

dual_tda1541a_dac_tube_buffer_board_reworks_1.png

dual_tda1541a_dac_tube_buffer_board_reworks_2.png

dual_tda1541a_dac_tube_buffer_board_reworks_3.png

dual_tda1541a_dac_tube_buffer_board_reworks_4.png


2. If U feel that the buffer board use 6.3V filament is OK than not need to use this modify.

If U use high efficiency speaker.>96db.

may be U will like to double up the filament Than use 317/337 to regulate. 6.3V double to 12.6V than rectify will approx 20C DC.
Than pass to 317/337 to regulate to 6.3V will drop approx 14~15V the heatsink look will not enough.
If U double the voltage, I suggest use large heatsink.

3. Try LT1033 & 1085.

these chips alll can pass 3A current, lower internal resistance & lower noise.
Will much better than 317/337(1.5A only).

4. I was design the re-clock which use TCXO (temperature
compensated Oscillator" 20ppmos. The Best I can get is this one in reasonable from japan.
Anyone can help me that use 74XXXXX will better with this chips??????
I prepare call the factory to buils this re-clock which use a small copper Box to fit for it. Ground the box will lower the noise.


ANY IDEA for the chips.


thanks

thomas
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Old 1st August 2004, 04:52 PM   #10
Coulomb is offline Coulomb  England
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Quote:
Originally posted by Coulomb
I am still waiting for my kit, meanwhile I have been looking at the AMVECO transformers. I am having trouble finding a 210-0-210 transformer for the tube stage, lots of single secondary 210 VAC, but dual, no luck yet. Any ideas other than running two transformers and tieing them together?

Regards

Anthony

Thomas any suggestions on my Transformer question?

Regards

Anthony
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