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Old 11th March 2009, 11:06 PM   #11
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Default not working

I removed the 74hc4040 chip and cyrstal ( schematic is on the first post here ) from the board and then operated as per philpoole's schematic...but no sound at all...but ok when I went back to my original setup.
I checked all connections from cs8414 to tda1541 dac and all seemed ok...does it matter that the reciever is not cs8412 as in philpoole's shematic ?
any tips what I should look for?.
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Old 11th March 2009, 11:13 PM   #12
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That wasn't my schematic!

I don't know the cs841x, but maybe you need to change a voltage on a setup pin to specify a different output mode or something?
More importantly, why did you see the need to remove it?

I think for a NOS DAC, you be better off improving power supplies, or something like that to start with.
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Old 11th March 2009, 11:29 PM   #13
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Quote:
Originally posted by philpoole
The resistors are used to reduce the current going into the DAC to reduce distortion. A LPF is apparently better still (I haven't tried).
No, there are not for "reducing the current". It's on digital side, current it is only ON or OFF. There are there for reducing the front of the signal. Signals with fast fronts can put out ridiculous edge rates which can cause EMI and couple to other traces, they can stress your power supply, they can cause ringing on traces that can make chips do weird things, you name it. Especially if are long traces and if there are going to a slower device (like the old TDA 1541).
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Old 11th March 2009, 11:39 PM   #14
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Thanks for the correction. However, from what I recall from the TDA1541 info thread (link below), a Philips engineer from the time mentioned this and its affect on the chip's substrate, and how also the voltage levels could be adjusted to improve matters, as well as an actual LPF.
I admit I haven't investigated this in detail, but simply refer to this thread - that's why I used the word 'apparently' for some of this.

I do also agree with your statements in the general sense, but I get the impression there is a special case here.

(Don't shoot the messenger)

TDA1541 info
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Old 12th March 2009, 12:22 AM   #15
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I see that there is the same opinion: "Not faster than 10 to 30nsec rise time. This rise time is already faster than required is the ft of the pnp is taken in acount. A lateral pnp is in this process not faster than 10MHz, a vertical pnp slightly faster."
The current in itself I don't think it is a problem, the chip is calculated for the TTL signals after all. But the ultra fast rise time it is what it was not taken into account at the time when this DAC was designed. CS has nice fronts for the modern circuits and for 96kHz Fs, but for this particular case it is different.
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Old 12th March 2009, 12:26 AM   #16
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Default good

Quote:
That wasn't my schematic!
Sorry....I should have said as supplied by philpoole.
Quote:
I don't know the cs841x, but maybe you need to change a voltage on a setup pin to specify a different output mode or something?
ok
Quote:
I think for a NOS DAC, you be better off improving power supplies, or something like that to start with.
Thanks for the tip
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Old 12th March 2009, 09:37 AM   #17
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But I didn't post the schematic either!

But I thought there was a discussion in there about not using TTL levels?

Anyway, nevermind. The net effect is the same even if my jargon seems wrong.
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Old 12th March 2009, 11:21 AM   #18
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Wink ooops

Quote:
But I didn't post the schematic either!
Bugger! ( another mistake )...hotiron supplied the schematic.....sorry bout that philpoole !
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Old 12th March 2009, 01:28 PM   #19
anbello is offline anbello  Italy
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Default Re: not working

Quote:
Originally posted by Chilli6565
I removed the 74hc4040 chip and cyrstal ( schematic is on the first post here ) from the board and then operated as per philpoole's schematic...but no sound at all...but ok when I went back to my original setup.
I checked all connections from cs8414 to tda1541 dac and all seemed ok...does it matter that the reciever is not cs8412 as in philpoole's shematic ?
any tips what I should look for?.

if you want try your dac without reclocking (HC4040 and XO removed) you have to change the 8414 from mode 3 (M0=1, M1=1, M2=0, M3=0) to mode 2 (M0=0, M1=1, M2=0, M3=0).
In mode 3 FSYNC and SCK are input (generated from XO and HC4040), in mode 2 are output generated internally with the clock recoverd via pll from spdif input.
As always it's all in the datasheet.

Ciao
Andrea
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Old 12th March 2009, 11:16 PM   #20
hotiron is offline hotiron  Scotland
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Default We are here to HELP

We are here to learn and help!!!
Take your egos to bed and dream>
Chilli6565 asked a simple and honest question!?
I believe he (Anbello) is trying to say!!!!!!!!
connect pins 13 and 23 to ground
and it will work without external clock.
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