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Old 7th April 2004, 10:37 PM   #11
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from my own post :

Quote:
If they are all new and from the same date, do they differ much in the same setup ? Of course they do differ, no need to discuss that as I tried to make clear in my post. The question is how much.
So 7 new S1 chips with same datecode. What are the results of the measurements ? We are debating something very vague now.

I don't want to kick in an open door but just a question: are you absolutely sure you've bought real S1's ? Their popularity makes them interesting for forgers. There are fake S1's around that are rebranded normal ones and sometimes even non A versions. If all the S1's that are on the market now ( 10, 15 years after production ) are real Philips would have produced absurd amounts of selected chips

I reread your post concerning swapping OPA2604 with NE5532 without any difference in testresults. They sound absolutely different though, regardless of testresults. Your comment on being the TDA solely responsible for the sound character is not an absolute truth in that aspect. Some things in audio can not be proved by measurements alone.
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Old 7th April 2004, 11:33 PM   #12
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Quote:
Originally posted by till


I have only built a D1 for tests p2p, not connected to any Dac now.

Do you have pictures or PCBs ? Do you plan a PCB for the balanced version?

Im still at collectiong parts, most are here now.

Not pics or PCB yet. But yes I plan for pcb balanced.
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Old 7th April 2004, 11:38 PM   #13
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Quote:
I have just implemented the Pass D1 at the 1541A and I am pleased with the results
Did you use just half of the original circuit with TDA 1541A?

Bartek
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Old 8th April 2004, 05:13 AM   #14
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Quote:
Originally posted by jean-paul
are you absolutely sure you've bought real S1's ?

Some things in audio can not be proved by measurements alone.
I expected that...

One can never be sure if they are original.

But the S1 behave like A chips, so they are not plain, that is for sure.
Funny, but if you give me a 1541 with removed printing I can tell 100% if this is plain or A version.

Still, I have 1541 A S1 from CD880 which can not be a fake, same for the plain 1541 S1.

Opamps:

The spectrum of each TDA chip is very characteristic.

I measure up to 9th harmonic, so there are 8 harmonics which are in the range between -43,1dB ( by the way, this worst value was found in the 1541A ) and -66dB.

With a resolution of 0,1dB, there are 230 values per harmonic.

My math is not good but i guess this is 230^8 possibilities.

The spectrum of a TDA chip is almost like a fingerprint, it is unlikely to find two identical ons, unless one tests a million.

If these subtle & characteristic ( about average 55dB below signal ) distortions are reproduced equal by two different opamps, how could they sound different ?
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Old 8th April 2004, 06:45 AM   #15
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Quote:
But the S1 behave like A chips, so they are not plain, that is for sure.
Funny, but if you give me a 1541 with removed printing I can tell 100% if this is plain or A version.

Still, I have 1541 A S1 from CD880 which can not be a fake, same for the plain 1541 S1.
Original A-S1's are selected A ones Bernhard. There are even non A versions rebranded as A-S1 around, not necessarily meaning that yours are like that. If the S1 ( that simply can't be fake ) from the 880 is the best or one of the better ones you can draw a ( premature ) conclusion. Just as premature as some of the conclusions already drawn ( not excluding my conclusions ) Like comparing chips in different cdplayers in this thread :

TDA1541 S1 listening problem

Quote:
If these subtle & characteristic ( about average 55dB below signal ) distortions are reproduced equal by two different opamps, how could they sound different ?
End of discussion. If you aren't ready to accept that you have to learn. Equal *looking* signals can sound different if you like it or not.
Although I don't take off sleeves of caps I once heard a demonstration of that and heard the difference. Black magic ? You can measure as much as you want but there won't be a difference in results on the test rig.

OPA2604 and NE5532 simply have another sound character, just as interlinks can have or resistors. An accepted phenomenon I would think ( but hard to get I admit ).
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Old 8th April 2004, 07:46 AM   #16
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Quote:
Originally posted by stefanobilliani
Hi ,

I have just implemented the Pass D1 at the 1541A and I am pleased with the results, even without the output buffers - it simplify the building life- the 1541A performs an round sounstage , defined very well from left to right ,high enough in a natural way , and ... above all ,the dinamics are not compressed in the bottom end with a clear and relaxed midrange .
I prefear the D1 above all I/V resistors and gainstages while it seems wasted with the 1543 .
Next step will be the balanced version for the 1541A.

Also 1543 sound more and more good in balanced mode: certainly if one pretends to use op amps and convert the balanced signal into single ended , the effort is lost .
To achieve the best from a balanced dac it is necessary to have after it a balanced circuitry .
********************

Regarding differences between channels 1543 is a champion expecially in volume , but the difference is coherent at the voltage level before the caps , and I find the cure in a trimmer .
Hello Stefano,
did you make any mod to the D1 stage to make it fit with the 1541A?
I'm very curious since I'm putting a great effort to make a good 1541 implementation, I have a PCB from Pedja (earlier version) with Elso's reclocker and want to try different I/V stages (I plan to compare Thorsten's OPA660 one, his tubed one with ECC88, Rudolf's super-pair and maybe the D1, even if I think that only half of it is needed).
After listening to them all I'll decide which one I like best.

From what you say the balanced version of the 1543 is really worth a try (too bad I don't have a completely balanced setup )

Cheers

Andrea
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Old 8th April 2004, 07:48 AM   #17
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Quote:
Originally posted by zygibajt


Did you use just half of the original circuit with TDA 1541A?

Bartek
For now the answer is yes , and I do not use the buffer (source follower) either .
Pratically it is one fet, 4 resistors , 1 trimmer ,3 caps par channel .Very simple.
In the future I will implement a balanced version and 2 TDA1541A.
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Old 8th April 2004, 07:59 AM   #18
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Quote:
Originally posted by Andypairo
did you make any mod to the D1 stage to make it fit with the 1541A?

The circuit works well as it is with 1541A, I am playing with different mosfets (irf610 , irfp044) just to enjoy differences in brightness/darkness of basses and highs; The buffers are not essential theyr absence simplify the construction.
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Old 8th April 2004, 08:03 AM   #19
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Default PCB???

Hi Stefano,

are you planning to make PCBs available? either SE or Balanced, (actually I would prefer SE). I think most people have problems when it comes to circuit boards for DACs. If no then do you have the track layout for the SE version so I could use the Press-N-Peel transfers? Please! Pretty Please!

Mozfet
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Old 8th April 2004, 08:17 AM   #20
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My dac consists of a reclocker, single flip flop/line in sinchronous mode and Tent clock. That is becouse I use the I2S directly from the CDP.
So if you use the CS8412 receiver it is another thing. BTW all I can do in the near future is a drawing of the lay out that is truly simple.
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